Stop running pub get at gclient sync time and fix build bugs

mojo/public/dart/third_party/analyzer/lib/src/generated/ast.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library engine.ast;
+
+import 'dart:collection';
+
+import 'element.dart';
+import 'engine.dart' show AnalysisEngine;
+import 'java_core.dart';
+import 'java_engine.dart';
+import 'parser.dart';
+import 'scanner.dart';
+import 'source.dart' show LineInfo, Source;
+import 'utilities_collection.dart' show TokenMap;
+import 'utilities_dart.dart';
+
+/**
+ * Two or more string literals that are implicitly concatenated because of being
+ * adjacent (separated only by whitespace).
+ *
+ * While the grammar only allows adjacent strings when all of the strings are of
+ * the same kind (single line or multi-line), this class doesn't enforce that
+ * restriction.
+ *
+ * > adjacentStrings ::=
+ * >     [StringLiteral] [StringLiteral]+
+ */
+class AdjacentStrings extends StringLiteral {
+  /**
+   * The strings that are implicitly concatenated.
+   */
+  NodeList<StringLiteral> _strings;
+
+  /**
+   * Initialize a newly created list of adjacent strings. To be syntactically
+   * valid, the list of [strings] must contain at least two elements.
+   */
+  AdjacentStrings(List<StringLiteral> strings) {
+    _strings = new NodeList<StringLiteral>(this, strings);
+  }
+
+  @override
+  Token get beginToken => _strings.beginToken;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..addAll(_strings);
+
+  @override
+  Token get endToken => _strings.endToken;
+
+  /**
+   * Return the strings that are implicitly concatenated.
+   */
+  NodeList<StringLiteral> get strings => _strings;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitAdjacentStrings(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _strings.accept(visitor);
+  }
+
+  @override
+  void _appendStringValue(StringBuffer buffer) {
+    for (StringLiteral stringLiteral in strings) {
+      stringLiteral._appendStringValue(buffer);
+    }
+  }
+}
+
+/**
+ * An AST node that can be annotated with both a documentation comment and a
+ * list of annotations.
+ */
+abstract class AnnotatedNode extends AstNode {
+  /**
+   * The documentation comment associated with this node, or `null` if this node
+   * does not have a documentation comment associated with it.
+   */
+  Comment _comment;
+
+  /**
+   * The annotations associated with this node.
+   */
+  NodeList<Annotation> _metadata;
+
+  /**
+   * Initialize a newly created annotated node. Either or both of the [comment]
+   * and [metadata] can be `null` if the node does not have the corresponding
+   * attribute.
+   */
+  AnnotatedNode(Comment comment, List<Annotation> metadata) {
+    _comment = _becomeParentOf(comment);
+    _metadata = new NodeList<Annotation>(this, metadata);
+  }
+
+  @override
+  Token get beginToken {
+    if (_comment == null) {
+      if (_metadata.isEmpty) {
+        return firstTokenAfterCommentAndMetadata;
+      }
+      return _metadata.beginToken;
+    } else if (_metadata.isEmpty) {
+      return _comment.beginToken;
+    }
+    Token commentToken = _comment.beginToken;
+    Token metadataToken = _metadata.beginToken;
+    if (commentToken.offset < metadataToken.offset) {
+      return commentToken;
+    }
+    return metadataToken;
+  }
+
+  /**
+   * Return the documentation comment associated with this node, or `null` if
+   * this node does not have a documentation comment associated with it.
+   */
+  Comment get documentationComment => _comment;
+
+  /**
+   * Set the documentation comment associated with this node to the given
+   * [comment].
+   */
+  void set documentationComment(Comment comment) {
+    _comment = _becomeParentOf(comment);
+  }
+
+  /**
+   * Return the first token following the comment and metadata.
+   */
+  Token get firstTokenAfterCommentAndMetadata;
+
+  /**
+   * Return the annotations associated with this node.
+   */
+  NodeList<Annotation> get metadata => _metadata;
+
+  /**
+   * Set the metadata associated with this node to the given [metadata].
+   */
+  @deprecated // Directly modify the list returned by "this.metadata"
+  void set metadata(List<Annotation> metadata) {
+    _metadata.clear();
+    _metadata.addAll(metadata);
+  }
+
+  /**
+   * Return a list containing the comment and annotations associated with this
+   * node, sorted in lexical order.
+   */
+  List<AstNode> get sortedCommentAndAnnotations {
+    return <AstNode>[]
+      ..add(_comment)
+      ..addAll(_metadata)
+      ..sort(AstNode.LEXICAL_ORDER);
+  }
+
+  /**
+   * Return a holder of child entities that subclasses can add to.
+   */
+  ChildEntities get _childEntities {
+    ChildEntities result = new ChildEntities();
+    if (_commentIsBeforeAnnotations()) {
+      result
+        ..add(_comment)
+        ..addAll(_metadata);
+    } else {
+      result.addAll(sortedCommentAndAnnotations);
+    }
+    return result;
+  }
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    if (_commentIsBeforeAnnotations()) {
+      _safelyVisitChild(_comment, visitor);
+      _metadata.accept(visitor);
+    } else {
+      for (AstNode child in sortedCommentAndAnnotations) {
+        child.accept(visitor);
+      }
+    }
+  }
+
+  /**
+   * Return `true` if there are no annotations before the comment. Note that a
+   * result of `true` does not imply that there is a comment, nor that there are
+   * annotations associated with this node.
+   */
+  bool _commentIsBeforeAnnotations() {
+    // TODO(brianwilkerson) Convert this to a getter.
+    if (_comment == null || _metadata.isEmpty) {
+      return true;
+    }
+    Annotation firstAnnotation = _metadata[0];
+    return _comment.offset < firstAnnotation.offset;
+  }
+}
+
+/**
+ * An annotation that can be associated with an AST node.
+ *
+ * > metadata ::=
+ * >     annotation*
+ * >
+ * > annotation ::=
+ * >     '@' [Identifier] ('.' [SimpleIdentifier])? [ArgumentList]?
+ */
+class Annotation extends AstNode {
+  /**
+   * The at sign that introduced the annotation.
+   */
+  Token atSign;
+
+  /**
+   * The name of the class defining the constructor that is being invoked or the
+   * name of the field that is being referenced.
+   */
+  Identifier _name;
+
+  /**
+   * The period before the constructor name, or `null` if this annotation is not
+   * the invocation of a named constructor.
+   */
+  Token period;
+
+  /**
+   * The name of the constructor being invoked, or `null` if this annotation is
+   * not the invocation of a named constructor.
+   */
+  SimpleIdentifier _constructorName;
+
+  /**
+   * The arguments to the constructor being invoked, or `null` if this
+   * annotation is not the invocation of a constructor.
+   */
+  ArgumentList _arguments;
+
+  /**
+   * The element associated with this annotation, or `null` if the AST structure
+   * has not been resolved or if this annotation could not be resolved.
+   */
+  Element _element;
+
+  /**
+   * The element annotation representing this annotation in the element model.
+   */
+  ElementAnnotation elementAnnotation;
+
+  /**
+   * Initialize a newly created annotation. Both the [period] and the
+   * [constructorName] can be `null` if the annotation is not referencing a
+   * named constructor. The [arguments] can be `null` if the annotation is not
+   * referencing a constructor.
+   */
+  Annotation(this.atSign, Identifier name, this.period,
+      SimpleIdentifier constructorName, ArgumentList arguments) {
+    _name = _becomeParentOf(name);
+    _constructorName = _becomeParentOf(constructorName);
+    _arguments = _becomeParentOf(arguments);
+  }
+
+  /**
+   * Return the arguments to the constructor being invoked, or `null` if this
+   * annotation is not the invocation of a constructor.
+   */
+  ArgumentList get arguments => _arguments;
+
+  /**
+   * Set the arguments to the constructor being invoked to the given arguments.
+   */
+  void set arguments(ArgumentList arguments) {
+    _arguments = _becomeParentOf(arguments);
+  }
+
+  @override
+  Token get beginToken => atSign;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(atSign)
+    ..add(_name)
+    ..add(period)
+    ..add(_constructorName)
+    ..add(_arguments);
+
+  /**
+   * Return the name of the constructor being invoked, or `null` if this
+   * annotation is not the invocation of a named constructor.
+   */
+  SimpleIdentifier get constructorName => _constructorName;
+
+  /**
+   * Set the name of the constructor being invoked to the given [name].
+   */
+  void set constructorName(SimpleIdentifier name) {
+    _constructorName = _becomeParentOf(name);
+  }
+
+  /**
+   * Return the element associated with this annotation, or `null` if the AST
+   * structure has not been resolved or if this annotation could not be
+   * resolved.
+   */
+  Element get element {
+    if (_element != null) {
+      return _element;
+    } else if (_name != null) {
+      return _name.staticElement;
+    }
+    return null;
+  }
+
+  /**
+   * Set the element associated with this annotation to the given [element].
+   */
+  void set element(Element element) {
+    _element = element;
+  }
+
+  @override
+  Token get endToken {
+    if (_arguments != null) {
+      return _arguments.endToken;
+    } else if (_constructorName != null) {
+      return _constructorName.endToken;
+    }
+    return _name.endToken;
+  }
+
+  /**
+   * Return the name of the class defining the constructor that is being invoked
+   * or the name of the field that is being referenced.
+   */
+  Identifier get name => _name;
+
+  /**
+   * Set the name of the class defining the constructor that is being invoked or
+   * the name of the field that is being referenced to the given [name].
+   */
+  void set name(Identifier name) {
+    _name = _becomeParentOf(name);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitAnnotation(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_constructorName, visitor);
+    _safelyVisitChild(_arguments, visitor);
+  }
+}
+
+/**
+ * A list of arguments in the invocation of an executable element (that is, a
+ * function, method, or constructor).
+ *
+ * > argumentList ::=
+ * >     '(' arguments? ')'
+ * >
+ * > arguments ::=
+ * >     [NamedExpression] (',' [NamedExpression])*
+ * >   | [Expression] (',' [Expression])* (',' [NamedExpression])*
+ */
+class ArgumentList extends AstNode {
+  /**
+   * The left parenthesis.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The expressions producing the values of the arguments.
+   */
+  NodeList<Expression> _arguments;
+
+  /**
+   * The right parenthesis.
+   */
+  Token rightParenthesis;
+
+  /**
+   * A list containing the elements representing the parameters corresponding to
+   * each of the arguments in this list, or `null` if the AST has not been
+   * resolved or if the function or method being invoked could not be determined
+   * based on static type information. The list must be the same length as the
+   * number of arguments, but can contain `null` entries if a given argument
+   * does not correspond to a formal parameter.
+   */
+  List<ParameterElement> _correspondingStaticParameters;
+
+  /**
+   * A list containing the elements representing the parameters corresponding to
+   * each of the arguments in this list, or `null` if the AST has not been
+   * resolved or if the function or method being invoked could not be determined
+   * based on propagated type information. The list must be the same length as
+   * the number of arguments, but can contain `null` entries if a given argument
+   * does not correspond to a formal parameter.
+   */
+  List<ParameterElement> _correspondingPropagatedParameters;
+
+  /**
+   * Initialize a newly created list of arguments. The list of [arguments] can
+   * be `null` if there are no arguments.
+   */
+  ArgumentList(
+      this.leftParenthesis, List<Expression> arguments, this.rightParenthesis) {
+    _arguments = new NodeList<Expression>(this, arguments);
+  }
+
+  /**
+   * Return the expressions producing the values of the arguments. Although the
+   * language requires that positional arguments appear before named arguments,
+   * this class allows them to be intermixed.
+   */
+  NodeList<Expression> get arguments => _arguments;
+
+  @override
+  Token get beginToken => leftParenthesis;
+
+  /**
+   * TODO(paulberry): Add commas.
+   */
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(leftParenthesis)
+    ..addAll(_arguments)
+    ..add(rightParenthesis);
+
+  /**
+   * Set the parameter elements corresponding to each of the arguments in this
+   * list to the given list of [parameters]. The list of parameters must be the
+   * same length as the number of arguments, but can contain `null` entries if a
+   * given argument does not correspond to a formal parameter.
+   */
+  void set correspondingPropagatedParameters(
+      List<ParameterElement> parameters) {
+    if (parameters.length != _arguments.length) {
+      throw new IllegalArgumentException(
+          "Expected ${_arguments.length} parameters, not ${parameters.length}");
+    }
+    _correspondingPropagatedParameters = parameters;
+  }
+
+  /**
+   * Set the parameter elements corresponding to each of the arguments in this
+   * list to the given list of parameters. The list of parameters must be the
+   * same length as the number of arguments, but can contain `null` entries if a
+   * given argument does not correspond to a formal parameter.
+   */
+  void set correspondingStaticParameters(List<ParameterElement> parameters) {
+    if (parameters.length != _arguments.length) {
+      throw new IllegalArgumentException(
+          "Expected ${_arguments.length} parameters, not ${parameters.length}");
+    }
+    _correspondingStaticParameters = parameters;
+  }
+
+  @override
+  Token get endToken => rightParenthesis;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitArgumentList(this);
+
+  /**
+   * If
+   * * the given [expression] is a child of this list,
+   * * the AST structure has been resolved,
+   * * the function being invoked is known based on propagated type information,
+   *   and
+   * * the expression corresponds to one of the parameters of the function being
+   *   invoked,
+   * then return the parameter element representing the parameter to which the
+   * value of the given expression will be bound. Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.propagatedParameterElement"
+  ParameterElement getPropagatedParameterElementFor(Expression expression) {
+    return _getPropagatedParameterElementFor(expression);
+  }
+
+  /**
+   * If
+   * * the given [expression] is a child of this list,
+   * * the AST structure has been resolved,
+   * * the function being invoked is known based on static type information, and
+   * * the expression corresponds to one of the parameters of the function being
+   *   invoked,
+   * then return the parameter element representing the parameter to which the
+   * value of the given expression will be bound. Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.staticParameterElement"
+  ParameterElement getStaticParameterElementFor(Expression expression) {
+    return _getStaticParameterElementFor(expression);
+  }
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _arguments.accept(visitor);
+  }
+
+  /**
+   * If
+   * * the given [expression] is a child of this list,
+   * * the AST structure has been resolved,
+   * * the function being invoked is known based on propagated type information,
+   *   and
+   * * the expression corresponds to one of the parameters of the function being
+   *   invoked,
+   * then return the parameter element representing the parameter to which the
+   * value of the given expression will be bound. Otherwise, return `null`.
+   */
+  ParameterElement _getPropagatedParameterElementFor(Expression expression) {
+    if (_correspondingPropagatedParameters == null ||
+        _correspondingPropagatedParameters.length != _arguments.length) {
+      // Either the AST structure has not been resolved, the invocation of which
+      // this list is a part could not be resolved, or the argument list was
+      // modified after the parameters were set.
+      return null;
+    }
+    int index = _arguments.indexOf(expression);
+    if (index < 0) {
+      // The expression isn't a child of this node.
+      return null;
+    }
+    return _correspondingPropagatedParameters[index];
+  }
+
+  /**
+   * If
+   * * the given [expression] is a child of this list,
+   * * the AST structure has been resolved,
+   * * the function being invoked is known based on static type information, and
+   * * the expression corresponds to one of the parameters of the function being
+   *   invoked,
+   * then return the parameter element representing the parameter to which the
+   * value of the given expression will be bound. Otherwise, return `null`.
+   */
+  ParameterElement _getStaticParameterElementFor(Expression expression) {
+    if (_correspondingStaticParameters == null ||
+        _correspondingStaticParameters.length != _arguments.length) {
+      // Either the AST structure has not been resolved, the invocation of which
+      // this list is a part could not be resolved, or the argument list was
+      // modified after the parameters were set.
+      return null;
+    }
+    int index = _arguments.indexOf(expression);
+    if (index < 0) {
+      // The expression isn't a child of this node.
+      return null;
+    }
+    return _correspondingStaticParameters[index];
+  }
+}
+
+/**
+ * An as expression.
+ *
+ * > asExpression ::=
+ * >     [Expression] 'as' [TypeName]
+ */
+class AsExpression extends Expression {
+  /**
+   * The expression used to compute the value being cast.
+   */
+  Expression _expression;
+
+  /**
+   * The 'as' operator.
+   */
+  Token asOperator;
+
+  /**
+   * The name of the type being cast to.
+   */
+  TypeName _type;
+
+  /**
+   * Initialize a newly created as expression.
+   */
+  AsExpression(Expression expression, this.asOperator, TypeName type) {
+    _expression = _becomeParentOf(expression);
+    _type = _becomeParentOf(type);
+  }
+
+  @override
+  Token get beginToken => _expression.beginToken;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_expression)..add(asOperator)..add(_type);
+
+  @override
+  Token get endToken => _type.endToken;
+
+  /**
+   * Return the expression used to compute the value being cast.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression used to compute the value being cast to the given
+   * [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  int get precedence => 7;
+
+  /**
+   * Return the name of the type being cast to.
+   */
+  TypeName get type => _type;
+
+  /**
+   * Set the name of the type being cast to to the given [name].
+   */
+  void set type(TypeName name) {
+    _type = _becomeParentOf(name);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitAsExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+    _safelyVisitChild(_type, visitor);
+  }
+}
+
+/**
+ * An assert statement.
+ *
+ * > assertStatement ::=
+ * >     'assert' '(' [Expression] ')' ';'
+ */
+class AssertStatement extends Statement {
+  /**
+   * The token representing the 'assert' keyword.
+   */
+  Token assertKeyword;
+
+  /**
+   * The left parenthesis.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The condition that is being asserted to be `true`.
+   */
+  Expression _condition;
+
+  /**
+   * The right parenthesis.
+   */
+  Token rightParenthesis;
+
+  /**
+   * The semicolon terminating the statement.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created assert statement.
+   */
+  AssertStatement(this.assertKeyword, this.leftParenthesis,
+      Expression condition, this.rightParenthesis, this.semicolon) {
+    _condition = _becomeParentOf(condition);
+  }
+
+  @override
+  Token get beginToken => assertKeyword;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(assertKeyword)
+    ..add(leftParenthesis)
+    ..add(_condition)
+    ..add(rightParenthesis)
+    ..add(semicolon);
+
+  /**
+   * Return the condition that is being asserted to be `true`.
+   */
+  Expression get condition => _condition;
+
+  /**
+   * Set the condition that is being asserted to be `true` to the given
+   * [expression].
+   */
+  void set condition(Expression condition) {
+    _condition = _becomeParentOf(condition);
+  }
+
+  @override
+  Token get endToken => semicolon;
+
+  /**
+   * Return the token representing the 'assert' keyword.
+   */
+  @deprecated // Use "this.assertKeyword"
+  Token get keyword => assertKeyword;
+
+  /**
+   * Set the token representing the 'assert' keyword to the given [token].
+   */
+  @deprecated // Use "this.assertKeyword"
+  set keyword(Token token) {
+    assertKeyword = token;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitAssertStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_condition, visitor);
+  }
+}
+
+/**
+ * An assignment expression.
+ *
+ * > assignmentExpression ::=
+ * >     [Expression] operator [Expression]
+ */
+class AssignmentExpression extends Expression {
+  /**
+   * The expression used to compute the left hand side.
+   */
+  Expression _leftHandSide;
+
+  /**
+   * The assignment operator being applied.
+   */
+  Token operator;
+
+  /**
+   * The expression used to compute the right hand side.
+   */
+  Expression _rightHandSide;
+
+  /**
+   * The element associated with the operator based on the static type of the
+   * left-hand-side, or `null` if the AST structure has not been resolved, if
+   * the operator is not a compound operator, or if the operator could not be
+   * resolved.
+   */
+  MethodElement staticElement;
+
+  /**
+   * The element associated with the operator based on the propagated type of
+   * the left-hand-side, or `null` if the AST structure has not been resolved,
+   * if the operator is not a compound operator, or if the operator could not be
+   * resolved.
+   */
+  MethodElement propagatedElement;
+
+  /**
+   * Initialize a newly created assignment expression.
+   */
+  AssignmentExpression(
+      Expression leftHandSide, this.operator, Expression rightHandSide) {
+    if (leftHandSide == null || rightHandSide == null) {
+      String message;
+      if (leftHandSide == null) {
+        if (rightHandSide == null) {
+          message = "Both the left-hand and right-hand sides are null";
+        } else {
+          message = "The left-hand size is null";
+        }
+      } else {
+        message = "The right-hand size is null";
+      }
+      AnalysisEngine.instance.logger.logError(
+          message, new CaughtException(new AnalysisException(message), null));
+    }
+    _leftHandSide = _becomeParentOf(leftHandSide);
+    _rightHandSide = _becomeParentOf(rightHandSide);
+  }
+
+  @override
+  Token get beginToken => _leftHandSide.beginToken;
+
+  /**
+   * Return the best element available for this operator. If resolution was able
+   * to find a better element based on type propagation, that element will be
+   * returned. Otherwise, the element found using the result of static analysis
+   * will be returned. If resolution has not been performed, then `null` will be
+   * returned.
+   */
+  MethodElement get bestElement {
+    MethodElement element = propagatedElement;
+    if (element == null) {
+      element = staticElement;
+    }
+    return element;
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(_leftHandSide)
+    ..add(operator)
+    ..add(_rightHandSide);
+
+  @override
+  Token get endToken => _rightHandSide.endToken;
+
+  /**
+   * Set the expression used to compute the left hand side to the given
+   * [expression].
+   */
+  Expression get leftHandSide => _leftHandSide;
+
+  /**
+   * Return the expression used to compute the left hand side.
+   */
+  void set leftHandSide(Expression expression) {
+    _leftHandSide = _becomeParentOf(expression);
+  }
+
+  @override
+  int get precedence => 1;
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on propagated type information, then return the parameter
+   * element representing the parameter to which the value of the right operand
+   * will be bound. Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.propagatedParameterElement"
+  ParameterElement get propagatedParameterElementForRightHandSide {
+    return _propagatedParameterElementForRightHandSide;
+  }
+
+  /**
+   * Return the expression used to compute the right hand side.
+   */
+  Expression get rightHandSide => _rightHandSide;
+
+  /**
+   * Set the expression used to compute the left hand side to the given
+   * [expression].
+   */
+  void set rightHandSide(Expression expression) {
+    _rightHandSide = _becomeParentOf(expression);
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on static type information, then return the parameter element
+   * representing the parameter to which the value of the right operand will be
+   * bound. Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.staticParameterElement"
+  ParameterElement get staticParameterElementForRightHandSide {
+    return _staticParameterElementForRightHandSide;
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on propagated type information, then return the parameter
+   * element representing the parameter to which the value of the right operand
+   * will be bound. Otherwise, return `null`.
+   */
+  ParameterElement get _propagatedParameterElementForRightHandSide {
+    ExecutableElement executableElement = null;
+    if (propagatedElement != null) {
+      executableElement = propagatedElement;
+    } else {
+      if (_leftHandSide is Identifier) {
+        Identifier identifier = _leftHandSide as Identifier;
+        Element leftElement = identifier.propagatedElement;
+        if (leftElement is ExecutableElement) {
+          executableElement = leftElement;
+        }
+      }
+      if (_leftHandSide is PropertyAccess) {
+        SimpleIdentifier identifier =
+            (_leftHandSide as PropertyAccess).propertyName;
+        Element leftElement = identifier.propagatedElement;
+        if (leftElement is ExecutableElement) {
+          executableElement = leftElement;
+        }
+      }
+    }
+    if (executableElement == null) {
+      return null;
+    }
+    List<ParameterElement> parameters = executableElement.parameters;
+    if (parameters.length < 1) {
+      return null;
+    }
+    return parameters[0];
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on static type information, then return the parameter element
+   * representing the parameter to which the value of the right operand will be
+   * bound. Otherwise, return `null`.
+   */
+  ParameterElement get _staticParameterElementForRightHandSide {
+    ExecutableElement executableElement = null;
+    if (staticElement != null) {
+      executableElement = staticElement;
+    } else {
+      if (_leftHandSide is Identifier) {
+        Element leftElement = (_leftHandSide as Identifier).staticElement;
+        if (leftElement is ExecutableElement) {
+          executableElement = leftElement;
+        }
+      }
+      if (_leftHandSide is PropertyAccess) {
+        Element leftElement =
+            (_leftHandSide as PropertyAccess).propertyName.staticElement;
+        if (leftElement is ExecutableElement) {
+          executableElement = leftElement;
+        }
+      }
+    }
+    if (executableElement == null) {
+      return null;
+    }
+    List<ParameterElement> parameters = executableElement.parameters;
+    if (parameters.length < 1) {
+      return null;
+    }
+    return parameters[0];
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitAssignmentExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_leftHandSide, visitor);
+    _safelyVisitChild(_rightHandSide, visitor);
+  }
+}
+
+/**
+ * An AST visitor that will clone any AST structure that it visits. The cloner
+ * will only clone the structure, it will not preserve any resolution results or
+ * properties associated with the nodes.
+ */
+class AstCloner implements AstVisitor<AstNode> {
+  /**
+   * A flag indicating whether tokens should be cloned while cloning an AST
+   * structure.
+   */
+  final bool cloneTokens;
+
+  /**
+   * Initialize a newly created AST cloner to optionally clone tokens while
+   * cloning AST nodes if [cloneTokens] is `true`.
+   */
+  AstCloner(
+      [this.cloneTokens = false]); // TODO(brianwilkerson) Change this to be a named parameter.
+
+  /**
+   * Return a clone of the given [node].
+   */
+  AstNode cloneNode(AstNode node) {
+    if (node == null) {
+      return null;
+    }
+    return node.accept(this) as AstNode;
+  }
+
+  /**
+   * Return a list containing cloned versions of the nodes in the given list of
+   * [nodes].
+   */
+  List<AstNode> cloneNodeList(NodeList nodes) {
+    int count = nodes.length;
+    List clonedNodes = new List();
+    for (int i = 0; i < count; i++) {
+      clonedNodes.add((nodes[i]).accept(this) as AstNode);
+    }
+    return clonedNodes;
+  }
+
+  /**
+   * Clone the given [token] if tokens are supposed to be cloned.
+   */
+  Token cloneToken(Token token) {
+    if (cloneTokens) {
+      return (token == null ? null : token.copy());
+    } else {
+      return token;
+    }
+  }
+
+  /**
+   * Clone the given [tokens] if tokens are supposed to be cloned.
+   */
+  List<Token> cloneTokenList(List<Token> tokens) {
+    if (cloneTokens) {
+      return tokens.map((Token token) => token.copy()).toList();
+    }
+    return tokens;
+  }
+
+  @override
+  AdjacentStrings visitAdjacentStrings(AdjacentStrings node) =>
+      new AdjacentStrings(cloneNodeList(node.strings));
+
+  @override
+  Annotation visitAnnotation(Annotation node) => new Annotation(
+      cloneToken(node.atSign), cloneNode(node.name), cloneToken(node.period),
+      cloneNode(node.constructorName), cloneNode(node.arguments));
+
+  @override
+  ArgumentList visitArgumentList(ArgumentList node) => new ArgumentList(
+      cloneToken(node.leftParenthesis), cloneNodeList(node.arguments),
+      cloneToken(node.rightParenthesis));
+
+  @override
+  AsExpression visitAsExpression(AsExpression node) => new AsExpression(
+      cloneNode(node.expression), cloneToken(node.asOperator),
+      cloneNode(node.type));
+
+  @override
+  AstNode visitAssertStatement(AssertStatement node) => new AssertStatement(
+      cloneToken(node.assertKeyword), cloneToken(node.leftParenthesis),
+      cloneNode(node.condition), cloneToken(node.rightParenthesis),
+      cloneToken(node.semicolon));
+
+  @override
+  AssignmentExpression visitAssignmentExpression(AssignmentExpression node) =>
+      new AssignmentExpression(cloneNode(node.leftHandSide),
+          cloneToken(node.operator), cloneNode(node.rightHandSide));
+
+  @override
+  AwaitExpression visitAwaitExpression(AwaitExpression node) =>
+      new AwaitExpression(
+          cloneToken(node.awaitKeyword), cloneNode(node.expression));
+
+  @override
+  BinaryExpression visitBinaryExpression(BinaryExpression node) =>
+      new BinaryExpression(cloneNode(node.leftOperand),
+          cloneToken(node.operator), cloneNode(node.rightOperand));
+
+  @override
+  Block visitBlock(Block node) => new Block(cloneToken(node.leftBracket),
+      cloneNodeList(node.statements), cloneToken(node.rightBracket));
+
+  @override
+  BlockFunctionBody visitBlockFunctionBody(
+      BlockFunctionBody node) => new BlockFunctionBody(
+      cloneToken(node.keyword), cloneToken(node.star), cloneNode(node.block));
+
+  @override
+  BooleanLiteral visitBooleanLiteral(BooleanLiteral node) =>
+      new BooleanLiteral(cloneToken(node.literal), node.value);
+
+  @override
+  BreakStatement visitBreakStatement(BreakStatement node) => new BreakStatement(
+      cloneToken(node.breakKeyword), cloneNode(node.label),
+      cloneToken(node.semicolon));
+
+  @override
+  CascadeExpression visitCascadeExpression(CascadeExpression node) =>
+      new CascadeExpression(
+          cloneNode(node.target), cloneNodeList(node.cascadeSections));
+
+  @override
+  CatchClause visitCatchClause(CatchClause node) => new CatchClause(
+      cloneToken(node.onKeyword), cloneNode(node.exceptionType),
+      cloneToken(node.catchKeyword), cloneToken(node.leftParenthesis),
+      cloneNode(node.exceptionParameter), cloneToken(node.comma),
+      cloneNode(node.stackTraceParameter), cloneToken(node.rightParenthesis),
+      cloneNode(node.body));
+
+  @override
+  ClassDeclaration visitClassDeclaration(ClassDeclaration node) {
+    ClassDeclaration copy = new ClassDeclaration(
+        cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+        cloneToken(node.abstractKeyword), cloneToken(node.classKeyword),
+        cloneNode(node.name), cloneNode(node.typeParameters),
+        cloneNode(node.extendsClause), cloneNode(node.withClause),
+        cloneNode(node.implementsClause), cloneToken(node.leftBracket),
+        cloneNodeList(node.members), cloneToken(node.rightBracket));
+    copy.nativeClause = cloneNode(node.nativeClause);
+    return copy;
+  }
+
+  @override
+  ClassTypeAlias visitClassTypeAlias(ClassTypeAlias node) => new ClassTypeAlias(
+      cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+      cloneToken(node.typedefKeyword), cloneNode(node.name),
+      cloneNode(node.typeParameters), cloneToken(node.equals),
+      cloneToken(node.abstractKeyword), cloneNode(node.superclass),
+      cloneNode(node.withClause), cloneNode(node.implementsClause),
+      cloneToken(node.semicolon));
+
+  @override
+  Comment visitComment(Comment node) {
+    if (node.isDocumentation) {
+      return Comment.createDocumentationCommentWithReferences(
+          cloneTokenList(node.tokens), cloneNodeList(node.references));
+    } else if (node.isBlock) {
+      return Comment.createBlockComment(cloneTokenList(node.tokens));
+    }
+    return Comment.createEndOfLineComment(cloneTokenList(node.tokens));
+  }
+
+  @override
+  CommentReference visitCommentReference(CommentReference node) =>
+      new CommentReference(
+          cloneToken(node.newKeyword), cloneNode(node.identifier));
+
+  @override
+  CompilationUnit visitCompilationUnit(CompilationUnit node) {
+    CompilationUnit clone = new CompilationUnit(cloneToken(node.beginToken),
+        cloneNode(node.scriptTag), cloneNodeList(node.directives),
+        cloneNodeList(node.declarations), cloneToken(node.endToken));
+    clone.lineInfo = node.lineInfo;
+    return clone;
+  }
+
+  @override
+  ConditionalExpression visitConditionalExpression(
+      ConditionalExpression node) => new ConditionalExpression(
+      cloneNode(node.condition), cloneToken(node.question),
+      cloneNode(node.thenExpression), cloneToken(node.colon),
+      cloneNode(node.elseExpression));
+
+  @override
+  ConstructorDeclaration visitConstructorDeclaration(
+      ConstructorDeclaration node) => new ConstructorDeclaration(
+      cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+      cloneToken(node.externalKeyword), cloneToken(node.constKeyword),
+      cloneToken(node.factoryKeyword), cloneNode(node.returnType),
+      cloneToken(node.period), cloneNode(node.name), cloneNode(node.parameters),
+      cloneToken(node.separator), cloneNodeList(node.initializers),
+      cloneNode(node.redirectedConstructor), cloneNode(node.body));
+
+  @override
+  ConstructorFieldInitializer visitConstructorFieldInitializer(
+      ConstructorFieldInitializer node) => new ConstructorFieldInitializer(
+      cloneToken(node.thisKeyword), cloneToken(node.period),
+      cloneNode(node.fieldName), cloneToken(node.equals),
+      cloneNode(node.expression));
+
+  @override
+  ConstructorName visitConstructorName(ConstructorName node) =>
+      new ConstructorName(
+          cloneNode(node.type), cloneToken(node.period), cloneNode(node.name));
+
+  @override
+  ContinueStatement visitContinueStatement(ContinueStatement node) =>
+      new ContinueStatement(cloneToken(node.continueKeyword),
+          cloneNode(node.label), cloneToken(node.semicolon));
+
+  @override
+  DeclaredIdentifier visitDeclaredIdentifier(DeclaredIdentifier node) =>
+      new DeclaredIdentifier(cloneNode(node.documentationComment),
+          cloneNodeList(node.metadata), cloneToken(node.keyword),
+          cloneNode(node.type), cloneNode(node.identifier));
+
+  @override
+  DefaultFormalParameter visitDefaultFormalParameter(
+      DefaultFormalParameter node) => new DefaultFormalParameter(
+      cloneNode(node.parameter), node.kind, cloneToken(node.separator),
+      cloneNode(node.defaultValue));
+
+  @override
+  DoStatement visitDoStatement(DoStatement node) => new DoStatement(
+      cloneToken(node.doKeyword), cloneNode(node.body),
+      cloneToken(node.whileKeyword), cloneToken(node.leftParenthesis),
+      cloneNode(node.condition), cloneToken(node.rightParenthesis),
+      cloneToken(node.semicolon));
+
+  @override
+  DoubleLiteral visitDoubleLiteral(DoubleLiteral node) =>
+      new DoubleLiteral(cloneToken(node.literal), node.value);
+
+  @override
+  EmptyFunctionBody visitEmptyFunctionBody(EmptyFunctionBody node) =>
+      new EmptyFunctionBody(cloneToken(node.semicolon));
+
+  @override
+  EmptyStatement visitEmptyStatement(EmptyStatement node) =>
+      new EmptyStatement(cloneToken(node.semicolon));
+
+  @override
+  AstNode visitEnumConstantDeclaration(EnumConstantDeclaration node) =>
+      new EnumConstantDeclaration(cloneNode(node.documentationComment),
+          cloneNodeList(node.metadata), cloneNode(node.name));
+
+  @override
+  EnumDeclaration visitEnumDeclaration(EnumDeclaration node) =>
+      new EnumDeclaration(cloneNode(node.documentationComment),
+          cloneNodeList(node.metadata), cloneToken(node.enumKeyword),
+          cloneNode(node.name), cloneToken(node.leftBracket),
+          cloneNodeList(node.constants), cloneToken(node.rightBracket));
+
+  @override
+  ExportDirective visitExportDirective(ExportDirective node) {
+    ExportDirective directive = new ExportDirective(
+        cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+        cloneToken(node.keyword), cloneNode(node.uri),
+        cloneNodeList(node.combinators), cloneToken(node.semicolon));
+    directive.source = node.source;
+    directive.uriContent = node.uriContent;
+    return directive;
+  }
+
+  @override
+  ExpressionFunctionBody visitExpressionFunctionBody(
+      ExpressionFunctionBody node) => new ExpressionFunctionBody(
+      cloneToken(node.keyword), cloneToken(node.functionDefinition),
+      cloneNode(node.expression), cloneToken(node.semicolon));
+
+  @override
+  ExpressionStatement visitExpressionStatement(ExpressionStatement node) =>
+      new ExpressionStatement(
+          cloneNode(node.expression), cloneToken(node.semicolon));
+
+  @override
+  ExtendsClause visitExtendsClause(ExtendsClause node) => new ExtendsClause(
+      cloneToken(node.extendsKeyword), cloneNode(node.superclass));
+
+  @override
+  FieldDeclaration visitFieldDeclaration(FieldDeclaration node) =>
+      new FieldDeclaration(cloneNode(node.documentationComment),
+          cloneNodeList(node.metadata), cloneToken(node.staticKeyword),
+          cloneNode(node.fields), cloneToken(node.semicolon));
+
+  @override
+  FieldFormalParameter visitFieldFormalParameter(FieldFormalParameter node) =>
+      new FieldFormalParameter(cloneNode(node.documentationComment),
+          cloneNodeList(node.metadata), cloneToken(node.keyword),
+          cloneNode(node.type), cloneToken(node.thisKeyword),
+          cloneToken(node.period), cloneNode(node.identifier),
+          cloneNode(node.typeParameters), cloneNode(node.parameters));
+
+  @override
+  ForEachStatement visitForEachStatement(ForEachStatement node) {
+    DeclaredIdentifier loopVariable = node.loopVariable;
+    if (loopVariable == null) {
+      return new ForEachStatement.withReference(cloneToken(node.awaitKeyword),
+          cloneToken(node.forKeyword), cloneToken(node.leftParenthesis),
+          cloneNode(node.identifier), cloneToken(node.inKeyword),
+          cloneNode(node.iterable), cloneToken(node.rightParenthesis),
+          cloneNode(node.body));
+    }
+    return new ForEachStatement.withDeclaration(cloneToken(node.awaitKeyword),
+        cloneToken(node.forKeyword), cloneToken(node.leftParenthesis),
+        cloneNode(loopVariable), cloneToken(node.inKeyword),
+        cloneNode(node.iterable), cloneToken(node.rightParenthesis),
+        cloneNode(node.body));
+  }
+
+  @override
+  FormalParameterList visitFormalParameterList(FormalParameterList node) =>
+      new FormalParameterList(cloneToken(node.leftParenthesis),
+          cloneNodeList(node.parameters), cloneToken(node.leftDelimiter),
+          cloneToken(node.rightDelimiter), cloneToken(node.rightParenthesis));
+
+  @override
+  ForStatement visitForStatement(ForStatement node) => new ForStatement(
+      cloneToken(node.forKeyword), cloneToken(node.leftParenthesis),
+      cloneNode(node.variables), cloneNode(node.initialization),
+      cloneToken(node.leftSeparator), cloneNode(node.condition),
+      cloneToken(node.rightSeparator), cloneNodeList(node.updaters),
+      cloneToken(node.rightParenthesis), cloneNode(node.body));
+
+  @override
+  FunctionDeclaration visitFunctionDeclaration(FunctionDeclaration node) =>
+      new FunctionDeclaration(cloneNode(node.documentationComment),
+          cloneNodeList(node.metadata), cloneToken(node.externalKeyword),
+          cloneNode(node.returnType), cloneToken(node.propertyKeyword),
+          cloneNode(node.name), cloneNode(node.functionExpression));
+
+  @override
+  FunctionDeclarationStatement visitFunctionDeclarationStatement(
+          FunctionDeclarationStatement node) =>
+      new FunctionDeclarationStatement(cloneNode(node.functionDeclaration));
+
+  @override
+  FunctionExpression visitFunctionExpression(FunctionExpression node) =>
+      new FunctionExpression(cloneNode(node.typeParameters),
+          cloneNode(node.parameters), cloneNode(node.body));
+
+  @override
+  FunctionExpressionInvocation visitFunctionExpressionInvocation(
+      FunctionExpressionInvocation node) => new FunctionExpressionInvocation(
+      cloneNode(node.function), cloneNode(node.typeArguments),
+      cloneNode(node.argumentList));
+
+  @override
+  FunctionTypeAlias visitFunctionTypeAlias(FunctionTypeAlias node) =>
+      new FunctionTypeAlias(cloneNode(node.documentationComment),
+          cloneNodeList(node.metadata), cloneToken(node.typedefKeyword),
+          cloneNode(node.returnType), cloneNode(node.name),
+          cloneNode(node.typeParameters), cloneNode(node.parameters),
+          cloneToken(node.semicolon));
+
+  @override
+  FunctionTypedFormalParameter visitFunctionTypedFormalParameter(
+      FunctionTypedFormalParameter node) => new FunctionTypedFormalParameter(
+      cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+      cloneNode(node.returnType), cloneNode(node.identifier),
+      cloneNode(node.typeParameters), cloneNode(node.parameters));
+
+  @override
+  HideCombinator visitHideCombinator(HideCombinator node) => new HideCombinator(
+      cloneToken(node.keyword), cloneNodeList(node.hiddenNames));
+
+  @override
+  IfStatement visitIfStatement(IfStatement node) => new IfStatement(
+      cloneToken(node.ifKeyword), cloneToken(node.leftParenthesis),
+      cloneNode(node.condition), cloneToken(node.rightParenthesis),
+      cloneNode(node.thenStatement), cloneToken(node.elseKeyword),
+      cloneNode(node.elseStatement));
+
+  @override
+  ImplementsClause visitImplementsClause(ImplementsClause node) =>
+      new ImplementsClause(
+          cloneToken(node.implementsKeyword), cloneNodeList(node.interfaces));
+
+  @override
+  ImportDirective visitImportDirective(ImportDirective node) {
+    ImportDirective directive = new ImportDirective(
+        cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+        cloneToken(node.keyword), cloneNode(node.uri),
+        cloneToken(node.deferredKeyword), cloneToken(node.asKeyword),
+        cloneNode(node.prefix), cloneNodeList(node.combinators),
+        cloneToken(node.semicolon));
+    directive.source = node.source;
+    directive.uriContent = node.uriContent;
+    return directive;
+  }
+
+  @override
+  IndexExpression visitIndexExpression(IndexExpression node) {
+    Token period = node.period;
+    if (period == null) {
+      return new IndexExpression.forTarget(cloneNode(node.target),
+          cloneToken(node.leftBracket), cloneNode(node.index),
+          cloneToken(node.rightBracket));
+    } else {
+      return new IndexExpression.forCascade(cloneToken(period),
+          cloneToken(node.leftBracket), cloneNode(node.index),
+          cloneToken(node.rightBracket));
+    }
+  }
+
+  @override
+  InstanceCreationExpression visitInstanceCreationExpression(
+      InstanceCreationExpression node) => new InstanceCreationExpression(
+      cloneToken(node.keyword), cloneNode(node.constructorName),
+      cloneNode(node.argumentList));
+
+  @override
+  IntegerLiteral visitIntegerLiteral(IntegerLiteral node) =>
+      new IntegerLiteral(cloneToken(node.literal), node.value);
+
+  @override
+  InterpolationExpression visitInterpolationExpression(
+      InterpolationExpression node) => new InterpolationExpression(
+      cloneToken(node.leftBracket), cloneNode(node.expression),
+      cloneToken(node.rightBracket));
+
+  @override
+  InterpolationString visitInterpolationString(InterpolationString node) =>
+      new InterpolationString(cloneToken(node.contents), node.value);
+
+  @override
+  IsExpression visitIsExpression(IsExpression node) => new IsExpression(
+      cloneNode(node.expression), cloneToken(node.isOperator),
+      cloneToken(node.notOperator), cloneNode(node.type));
+
+  @override
+  Label visitLabel(Label node) =>
+      new Label(cloneNode(node.label), cloneToken(node.colon));
+
+  @override
+  LabeledStatement visitLabeledStatement(LabeledStatement node) =>
+      new LabeledStatement(
+          cloneNodeList(node.labels), cloneNode(node.statement));
+
+  @override
+  LibraryDirective visitLibraryDirective(LibraryDirective node) =>
+      new LibraryDirective(cloneNode(node.documentationComment),
+          cloneNodeList(node.metadata), cloneToken(node.libraryKeyword),
+          cloneNode(node.name), cloneToken(node.semicolon));
+
+  @override
+  LibraryIdentifier visitLibraryIdentifier(LibraryIdentifier node) =>
+      new LibraryIdentifier(cloneNodeList(node.components));
+
+  @override
+  ListLiteral visitListLiteral(ListLiteral node) => new ListLiteral(
+      cloneToken(node.constKeyword), cloneNode(node.typeArguments),
+      cloneToken(node.leftBracket), cloneNodeList(node.elements),
+      cloneToken(node.rightBracket));
+
+  @override
+  MapLiteral visitMapLiteral(MapLiteral node) => new MapLiteral(
+      cloneToken(node.constKeyword), cloneNode(node.typeArguments),
+      cloneToken(node.leftBracket), cloneNodeList(node.entries),
+      cloneToken(node.rightBracket));
+
+  @override
+  MapLiteralEntry visitMapLiteralEntry(
+      MapLiteralEntry node) => new MapLiteralEntry(
+      cloneNode(node.key), cloneToken(node.separator), cloneNode(node.value));
+
+  @override
+  MethodDeclaration visitMethodDeclaration(MethodDeclaration node) =>
+      new MethodDeclaration(cloneNode(node.documentationComment),
+          cloneNodeList(node.metadata), cloneToken(node.externalKeyword),
+          cloneToken(node.modifierKeyword), cloneNode(node.returnType),
+          cloneToken(node.propertyKeyword), cloneToken(node.operatorKeyword),
+          cloneNode(node.name), cloneNode(node.typeParameters),
+          cloneNode(node.parameters), cloneNode(node.body));
+
+  @override
+  MethodInvocation visitMethodInvocation(MethodInvocation node) =>
+      new MethodInvocation(cloneNode(node.target), cloneToken(node.operator),
+          cloneNode(node.methodName), cloneNode(node.typeArguments),
+          cloneNode(node.argumentList));
+
+  @override
+  NamedExpression visitNamedExpression(NamedExpression node) =>
+      new NamedExpression(cloneNode(node.name), cloneNode(node.expression));
+
+  @override
+  AstNode visitNativeClause(NativeClause node) =>
+      new NativeClause(cloneToken(node.nativeKeyword), cloneNode(node.name));
+
+  @override
+  NativeFunctionBody visitNativeFunctionBody(NativeFunctionBody node) =>
+      new NativeFunctionBody(cloneToken(node.nativeKeyword),
+          cloneNode(node.stringLiteral), cloneToken(node.semicolon));
+
+  @override
+  NullLiteral visitNullLiteral(NullLiteral node) =>
+      new NullLiteral(cloneToken(node.literal));
+
+  @override
+  ParenthesizedExpression visitParenthesizedExpression(
+      ParenthesizedExpression node) => new ParenthesizedExpression(
+      cloneToken(node.leftParenthesis), cloneNode(node.expression),
+      cloneToken(node.rightParenthesis));
+
+  @override
+  PartDirective visitPartDirective(PartDirective node) {
+    PartDirective directive = new PartDirective(
+        cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+        cloneToken(node.partKeyword), cloneNode(node.uri),
+        cloneToken(node.semicolon));
+    directive.source = node.source;
+    directive.uriContent = node.uriContent;
+    return directive;
+  }
+
+  @override
+  PartOfDirective visitPartOfDirective(PartOfDirective node) =>
+      new PartOfDirective(cloneNode(node.documentationComment),
+          cloneNodeList(node.metadata), cloneToken(node.partKeyword),
+          cloneToken(node.ofKeyword), cloneNode(node.libraryName),
+          cloneToken(node.semicolon));
+
+  @override
+  PostfixExpression visitPostfixExpression(PostfixExpression node) =>
+      new PostfixExpression(cloneNode(node.operand), cloneToken(node.operator));
+
+  @override
+  PrefixedIdentifier visitPrefixedIdentifier(PrefixedIdentifier node) =>
+      new PrefixedIdentifier(cloneNode(node.prefix), cloneToken(node.period),
+          cloneNode(node.identifier));
+
+  @override
+  PrefixExpression visitPrefixExpression(PrefixExpression node) =>
+      new PrefixExpression(cloneToken(node.operator), cloneNode(node.operand));
+
+  @override
+  PropertyAccess visitPropertyAccess(PropertyAccess node) => new PropertyAccess(
+      cloneNode(node.target), cloneToken(node.operator),
+      cloneNode(node.propertyName));
+
+  @override
+  RedirectingConstructorInvocation visitRedirectingConstructorInvocation(
+          RedirectingConstructorInvocation node) =>
+      new RedirectingConstructorInvocation(cloneToken(node.thisKeyword),
+          cloneToken(node.period), cloneNode(node.constructorName),
+          cloneNode(node.argumentList));
+
+  @override
+  RethrowExpression visitRethrowExpression(RethrowExpression node) =>
+      new RethrowExpression(cloneToken(node.rethrowKeyword));
+
+  @override
+  ReturnStatement visitReturnStatement(ReturnStatement node) =>
+      new ReturnStatement(cloneToken(node.returnKeyword),
+          cloneNode(node.expression), cloneToken(node.semicolon));
+
+  @override
+  ScriptTag visitScriptTag(ScriptTag node) =>
+      new ScriptTag(cloneToken(node.scriptTag));
+
+  @override
+  ShowCombinator visitShowCombinator(ShowCombinator node) => new ShowCombinator(
+      cloneToken(node.keyword), cloneNodeList(node.shownNames));
+
+  @override
+  SimpleFormalParameter visitSimpleFormalParameter(
+      SimpleFormalParameter node) => new SimpleFormalParameter(
+      cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+      cloneToken(node.keyword), cloneNode(node.type),
+      cloneNode(node.identifier));
+
+  @override
+  SimpleIdentifier visitSimpleIdentifier(SimpleIdentifier node) =>
+      new SimpleIdentifier(cloneToken(node.token));
+
+  @override
+  SimpleStringLiteral visitSimpleStringLiteral(SimpleStringLiteral node) =>
+      new SimpleStringLiteral(cloneToken(node.literal), node.value);
+
+  @override
+  StringInterpolation visitStringInterpolation(StringInterpolation node) =>
+      new StringInterpolation(cloneNodeList(node.elements));
+
+  @override
+  SuperConstructorInvocation visitSuperConstructorInvocation(
+      SuperConstructorInvocation node) => new SuperConstructorInvocation(
+      cloneToken(node.superKeyword), cloneToken(node.period),
+      cloneNode(node.constructorName), cloneNode(node.argumentList));
+
+  @override
+  SuperExpression visitSuperExpression(SuperExpression node) =>
+      new SuperExpression(cloneToken(node.superKeyword));
+
+  @override
+  SwitchCase visitSwitchCase(SwitchCase node) => new SwitchCase(
+      cloneNodeList(node.labels), cloneToken(node.keyword),
+      cloneNode(node.expression), cloneToken(node.colon),
+      cloneNodeList(node.statements));
+
+  @override
+  SwitchDefault visitSwitchDefault(SwitchDefault node) => new SwitchDefault(
+      cloneNodeList(node.labels), cloneToken(node.keyword),
+      cloneToken(node.colon), cloneNodeList(node.statements));
+
+  @override
+  SwitchStatement visitSwitchStatement(SwitchStatement node) =>
+      new SwitchStatement(cloneToken(node.switchKeyword),
+          cloneToken(node.leftParenthesis), cloneNode(node.expression),
+          cloneToken(node.rightParenthesis), cloneToken(node.leftBracket),
+          cloneNodeList(node.members), cloneToken(node.rightBracket));
+
+  @override
+  SymbolLiteral visitSymbolLiteral(SymbolLiteral node) => new SymbolLiteral(
+      cloneToken(node.poundSign), cloneTokenList(node.components));
+
+  @override
+  ThisExpression visitThisExpression(ThisExpression node) =>
+      new ThisExpression(cloneToken(node.thisKeyword));
+
+  @override
+  ThrowExpression visitThrowExpression(ThrowExpression node) =>
+      new ThrowExpression(
+          cloneToken(node.throwKeyword), cloneNode(node.expression));
+
+  @override
+  TopLevelVariableDeclaration visitTopLevelVariableDeclaration(
+      TopLevelVariableDeclaration node) => new TopLevelVariableDeclaration(
+      cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+      cloneNode(node.variables), cloneToken(node.semicolon));
+
+  @override
+  TryStatement visitTryStatement(TryStatement node) => new TryStatement(
+      cloneToken(node.tryKeyword), cloneNode(node.body),
+      cloneNodeList(node.catchClauses), cloneToken(node.finallyKeyword),
+      cloneNode(node.finallyBlock));
+
+  @override
+  TypeArgumentList visitTypeArgumentList(TypeArgumentList node) =>
+      new TypeArgumentList(cloneToken(node.leftBracket),
+          cloneNodeList(node.arguments), cloneToken(node.rightBracket));
+
+  @override
+  TypeName visitTypeName(TypeName node) =>
+      new TypeName(cloneNode(node.name), cloneNode(node.typeArguments));
+
+  @override
+  TypeParameter visitTypeParameter(TypeParameter node) => new TypeParameter(
+      cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+      cloneNode(node.name), cloneToken(node.extendsKeyword),
+      cloneNode(node.bound));
+
+  @override
+  TypeParameterList visitTypeParameterList(TypeParameterList node) =>
+      new TypeParameterList(cloneToken(node.leftBracket),
+          cloneNodeList(node.typeParameters), cloneToken(node.rightBracket));
+
+  @override
+  VariableDeclaration visitVariableDeclaration(VariableDeclaration node) =>
+      new VariableDeclaration(cloneNode(node.name), cloneToken(node.equals),
+          cloneNode(node.initializer));
+
+  @override
+  VariableDeclarationList visitVariableDeclarationList(
+      VariableDeclarationList node) => new VariableDeclarationList(
+      cloneNode(node.documentationComment), cloneNodeList(node.metadata),
+      cloneToken(node.keyword), cloneNode(node.type),
+      cloneNodeList(node.variables));
+
+  @override
+  VariableDeclarationStatement visitVariableDeclarationStatement(
+      VariableDeclarationStatement node) => new VariableDeclarationStatement(
+      cloneNode(node.variables), cloneToken(node.semicolon));
+
+  @override
+  WhileStatement visitWhileStatement(WhileStatement node) => new WhileStatement(
+      cloneToken(node.whileKeyword), cloneToken(node.leftParenthesis),
+      cloneNode(node.condition), cloneToken(node.rightParenthesis),
+      cloneNode(node.body));
+
+  @override
+  WithClause visitWithClause(WithClause node) => new WithClause(
+      cloneToken(node.withKeyword), cloneNodeList(node.mixinTypes));
+
+  @override
+  YieldStatement visitYieldStatement(YieldStatement node) => new YieldStatement(
+      cloneToken(node.yieldKeyword), cloneToken(node.star),
+      cloneNode(node.expression), cloneToken(node.semicolon));
+
+  /**
+   * Return a clone of the given [node].
+   */
+  static AstNode clone(AstNode node) {
+    return node.accept(new AstCloner());
+  }
+}
+
+/**
+ * An AstVisitor that compares the structure of two AstNodes to see whether they
+ * are equal.
+ */
+class AstComparator implements AstVisitor<bool> {
+  /**
+   * The AST node with which the node being visited is to be compared. This is
+   * only valid at the beginning of each visit method (until [isEqualNodes] is
+   * invoked).
+   */
+  AstNode _other;
+
+  /**
+   * Return `true` if the [first] node and the [second] node have the same
+   * structure.
+   *
+   * *Note:* This method is only visible for testing purposes and should not be
+   * used by clients.
+   */
+  bool isEqualNodes(AstNode first, AstNode second) {
+    if (first == null) {
+      return second == null;
+    } else if (second == null) {
+      return false;
+    } else if (first.runtimeType != second.runtimeType) {
+      return false;
+    }
+    _other = second;
+    return first.accept(this);
+  }
+
+  /**
+   * Return `true` if the [first] token and the [second] token have the same
+   * structure.
+   *
+   * *Note:* This method is only visible for testing purposes and should not be
+   * used by clients.
+   */
+  bool isEqualTokens(Token first, Token second) {
+    if (first == null) {
+      return second == null;
+    } else if (second == null) {
+      return false;
+    } else if (identical(first, second)) {
+      return true;
+    }
+    return first.offset == second.offset &&
+        first.length == second.length &&
+        first.lexeme == second.lexeme;
+  }
+
+  @override
+  bool visitAdjacentStrings(AdjacentStrings node) {
+    AdjacentStrings other = _other as AdjacentStrings;
+    return _isEqualNodeLists(node.strings, other.strings);
+  }
+
+  @override
+  bool visitAnnotation(Annotation node) {
+    Annotation other = _other as Annotation;
+    return isEqualTokens(node.atSign, other.atSign) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualTokens(node.period, other.period) &&
+        isEqualNodes(node.constructorName, other.constructorName) &&
+        isEqualNodes(node.arguments, other.arguments);
+  }
+
+  @override
+  bool visitArgumentList(ArgumentList node) {
+    ArgumentList other = _other as ArgumentList;
+    return isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        _isEqualNodeLists(node.arguments, other.arguments) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis);
+  }
+
+  @override
+  bool visitAsExpression(AsExpression node) {
+    AsExpression other = _other as AsExpression;
+    return isEqualNodes(node.expression, other.expression) &&
+        isEqualTokens(node.asOperator, other.asOperator) &&
+        isEqualNodes(node.type, other.type);
+  }
+
+  @override
+  bool visitAssertStatement(AssertStatement node) {
+    AssertStatement other = _other as AssertStatement;
+    return isEqualTokens(node.assertKeyword, other.assertKeyword) &&
+        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        isEqualNodes(node.condition, other.condition) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitAssignmentExpression(AssignmentExpression node) {
+    AssignmentExpression other = _other as AssignmentExpression;
+    return isEqualNodes(node.leftHandSide, other.leftHandSide) &&
+        isEqualTokens(node.operator, other.operator) &&
+        isEqualNodes(node.rightHandSide, other.rightHandSide);
+  }
+
+  @override
+  bool visitAwaitExpression(AwaitExpression node) {
+    AwaitExpression other = _other as AwaitExpression;
+    return isEqualTokens(node.awaitKeyword, other.awaitKeyword) &&
+        isEqualNodes(node.expression, other.expression);
+  }
+
+  @override
+  bool visitBinaryExpression(BinaryExpression node) {
+    BinaryExpression other = _other as BinaryExpression;
+    return isEqualNodes(node.leftOperand, other.leftOperand) &&
+        isEqualTokens(node.operator, other.operator) &&
+        isEqualNodes(node.rightOperand, other.rightOperand);
+  }
+
+  @override
+  bool visitBlock(Block node) {
+    Block other = _other as Block;
+    return isEqualTokens(node.leftBracket, other.leftBracket) &&
+        _isEqualNodeLists(node.statements, other.statements) &&
+        isEqualTokens(node.rightBracket, other.rightBracket);
+  }
+
+  @override
+  bool visitBlockFunctionBody(BlockFunctionBody node) {
+    BlockFunctionBody other = _other as BlockFunctionBody;
+    return isEqualNodes(node.block, other.block);
+  }
+
+  @override
+  bool visitBooleanLiteral(BooleanLiteral node) {
+    BooleanLiteral other = _other as BooleanLiteral;
+    return isEqualTokens(node.literal, other.literal) &&
+        node.value == other.value;
+  }
+
+  @override
+  bool visitBreakStatement(BreakStatement node) {
+    BreakStatement other = _other as BreakStatement;
+    return isEqualTokens(node.breakKeyword, other.breakKeyword) &&
+        isEqualNodes(node.label, other.label) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitCascadeExpression(CascadeExpression node) {
+    CascadeExpression other = _other as CascadeExpression;
+    return isEqualNodes(node.target, other.target) &&
+        _isEqualNodeLists(node.cascadeSections, other.cascadeSections);
+  }
+
+  @override
+  bool visitCatchClause(CatchClause node) {
+    CatchClause other = _other as CatchClause;
+    return isEqualTokens(node.onKeyword, other.onKeyword) &&
+        isEqualNodes(node.exceptionType, other.exceptionType) &&
+        isEqualTokens(node.catchKeyword, other.catchKeyword) &&
+        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        isEqualNodes(node.exceptionParameter, other.exceptionParameter) &&
+        isEqualTokens(node.comma, other.comma) &&
+        isEqualNodes(node.stackTraceParameter, other.stackTraceParameter) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
+        isEqualNodes(node.body, other.body);
+  }
+
+  @override
+  bool visitClassDeclaration(ClassDeclaration node) {
+    ClassDeclaration other = _other as ClassDeclaration;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.abstractKeyword, other.abstractKeyword) &&
+        isEqualTokens(node.classKeyword, other.classKeyword) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualNodes(node.typeParameters, other.typeParameters) &&
+        isEqualNodes(node.extendsClause, other.extendsClause) &&
+        isEqualNodes(node.withClause, other.withClause) &&
+        isEqualNodes(node.implementsClause, other.implementsClause) &&
+        isEqualTokens(node.leftBracket, other.leftBracket) &&
+        _isEqualNodeLists(node.members, other.members) &&
+        isEqualTokens(node.rightBracket, other.rightBracket);
+  }
+
+  @override
+  bool visitClassTypeAlias(ClassTypeAlias node) {
+    ClassTypeAlias other = _other as ClassTypeAlias;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.typedefKeyword, other.typedefKeyword) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualNodes(node.typeParameters, other.typeParameters) &&
+        isEqualTokens(node.equals, other.equals) &&
+        isEqualTokens(node.abstractKeyword, other.abstractKeyword) &&
+        isEqualNodes(node.superclass, other.superclass) &&
+        isEqualNodes(node.withClause, other.withClause) &&
+        isEqualNodes(node.implementsClause, other.implementsClause) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitComment(Comment node) {
+    Comment other = _other as Comment;
+    return _isEqualNodeLists(node.references, other.references);
+  }
+
+  @override
+  bool visitCommentReference(CommentReference node) {
+    CommentReference other = _other as CommentReference;
+    return isEqualTokens(node.newKeyword, other.newKeyword) &&
+        isEqualNodes(node.identifier, other.identifier);
+  }
+
+  @override
+  bool visitCompilationUnit(CompilationUnit node) {
+    CompilationUnit other = _other as CompilationUnit;
+    return isEqualTokens(node.beginToken, other.beginToken) &&
+        isEqualNodes(node.scriptTag, other.scriptTag) &&
+        _isEqualNodeLists(node.directives, other.directives) &&
+        _isEqualNodeLists(node.declarations, other.declarations) &&
+        isEqualTokens(node.endToken, other.endToken);
+  }
+
+  @override
+  bool visitConditionalExpression(ConditionalExpression node) {
+    ConditionalExpression other = _other as ConditionalExpression;
+    return isEqualNodes(node.condition, other.condition) &&
+        isEqualTokens(node.question, other.question) &&
+        isEqualNodes(node.thenExpression, other.thenExpression) &&
+        isEqualTokens(node.colon, other.colon) &&
+        isEqualNodes(node.elseExpression, other.elseExpression);
+  }
+
+  @override
+  bool visitConstructorDeclaration(ConstructorDeclaration node) {
+    ConstructorDeclaration other = _other as ConstructorDeclaration;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.externalKeyword, other.externalKeyword) &&
+        isEqualTokens(node.constKeyword, other.constKeyword) &&
+        isEqualTokens(node.factoryKeyword, other.factoryKeyword) &&
+        isEqualNodes(node.returnType, other.returnType) &&
+        isEqualTokens(node.period, other.period) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualNodes(node.parameters, other.parameters) &&
+        isEqualTokens(node.separator, other.separator) &&
+        _isEqualNodeLists(node.initializers, other.initializers) &&
+        isEqualNodes(node.redirectedConstructor, other.redirectedConstructor) &&
+        isEqualNodes(node.body, other.body);
+  }
+
+  @override
+  bool visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
+    ConstructorFieldInitializer other = _other as ConstructorFieldInitializer;
+    return isEqualTokens(node.thisKeyword, other.thisKeyword) &&
+        isEqualTokens(node.period, other.period) &&
+        isEqualNodes(node.fieldName, other.fieldName) &&
+        isEqualTokens(node.equals, other.equals) &&
+        isEqualNodes(node.expression, other.expression);
+  }
+
+  @override
+  bool visitConstructorName(ConstructorName node) {
+    ConstructorName other = _other as ConstructorName;
+    return isEqualNodes(node.type, other.type) &&
+        isEqualTokens(node.period, other.period) &&
+        isEqualNodes(node.name, other.name);
+  }
+
+  @override
+  bool visitContinueStatement(ContinueStatement node) {
+    ContinueStatement other = _other as ContinueStatement;
+    return isEqualTokens(node.continueKeyword, other.continueKeyword) &&
+        isEqualNodes(node.label, other.label) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitDeclaredIdentifier(DeclaredIdentifier node) {
+    DeclaredIdentifier other = _other as DeclaredIdentifier;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.keyword, other.keyword) &&
+        isEqualNodes(node.type, other.type) &&
+        isEqualNodes(node.identifier, other.identifier);
+  }
+
+  @override
+  bool visitDefaultFormalParameter(DefaultFormalParameter node) {
+    DefaultFormalParameter other = _other as DefaultFormalParameter;
+    return isEqualNodes(node.parameter, other.parameter) &&
+        node.kind == other.kind &&
+        isEqualTokens(node.separator, other.separator) &&
+        isEqualNodes(node.defaultValue, other.defaultValue);
+  }
+
+  @override
+  bool visitDoStatement(DoStatement node) {
+    DoStatement other = _other as DoStatement;
+    return isEqualTokens(node.doKeyword, other.doKeyword) &&
+        isEqualNodes(node.body, other.body) &&
+        isEqualTokens(node.whileKeyword, other.whileKeyword) &&
+        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        isEqualNodes(node.condition, other.condition) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitDoubleLiteral(DoubleLiteral node) {
+    DoubleLiteral other = _other as DoubleLiteral;
+    return isEqualTokens(node.literal, other.literal) &&
+        node.value == other.value;
+  }
+
+  @override
+  bool visitEmptyFunctionBody(EmptyFunctionBody node) {
+    EmptyFunctionBody other = _other as EmptyFunctionBody;
+    return isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitEmptyStatement(EmptyStatement node) {
+    EmptyStatement other = _other as EmptyStatement;
+    return isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitEnumConstantDeclaration(EnumConstantDeclaration node) {
+    EnumConstantDeclaration other = _other as EnumConstantDeclaration;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualNodes(node.name, other.name);
+  }
+
+  @override
+  bool visitEnumDeclaration(EnumDeclaration node) {
+    EnumDeclaration other = _other as EnumDeclaration;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.enumKeyword, other.enumKeyword) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualTokens(node.leftBracket, other.leftBracket) &&
+        _isEqualNodeLists(node.constants, other.constants) &&
+        isEqualTokens(node.rightBracket, other.rightBracket);
+  }
+
+  @override
+  bool visitExportDirective(ExportDirective node) {
+    ExportDirective other = _other as ExportDirective;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.keyword, other.keyword) &&
+        isEqualNodes(node.uri, other.uri) &&
+        _isEqualNodeLists(node.combinators, other.combinators) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitExpressionFunctionBody(ExpressionFunctionBody node) {
+    ExpressionFunctionBody other = _other as ExpressionFunctionBody;
+    return isEqualTokens(node.functionDefinition, other.functionDefinition) &&
+        isEqualNodes(node.expression, other.expression) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitExpressionStatement(ExpressionStatement node) {
+    ExpressionStatement other = _other as ExpressionStatement;
+    return isEqualNodes(node.expression, other.expression) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitExtendsClause(ExtendsClause node) {
+    ExtendsClause other = _other as ExtendsClause;
+    return isEqualTokens(node.extendsKeyword, other.extendsKeyword) &&
+        isEqualNodes(node.superclass, other.superclass);
+  }
+
+  @override
+  bool visitFieldDeclaration(FieldDeclaration node) {
+    FieldDeclaration other = _other as FieldDeclaration;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.staticKeyword, other.staticKeyword) &&
+        isEqualNodes(node.fields, other.fields) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitFieldFormalParameter(FieldFormalParameter node) {
+    FieldFormalParameter other = _other as FieldFormalParameter;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.keyword, other.keyword) &&
+        isEqualNodes(node.type, other.type) &&
+        isEqualTokens(node.thisKeyword, other.thisKeyword) &&
+        isEqualTokens(node.period, other.period) &&
+        isEqualNodes(node.identifier, other.identifier);
+  }
+
+  @override
+  bool visitForEachStatement(ForEachStatement node) {
+    ForEachStatement other = _other as ForEachStatement;
+    return isEqualTokens(node.forKeyword, other.forKeyword) &&
+        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        isEqualNodes(node.loopVariable, other.loopVariable) &&
+        isEqualTokens(node.inKeyword, other.inKeyword) &&
+        isEqualNodes(node.iterable, other.iterable) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
+        isEqualNodes(node.body, other.body);
+  }
+
+  @override
+  bool visitFormalParameterList(FormalParameterList node) {
+    FormalParameterList other = _other as FormalParameterList;
+    return isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        _isEqualNodeLists(node.parameters, other.parameters) &&
+        isEqualTokens(node.leftDelimiter, other.leftDelimiter) &&
+        isEqualTokens(node.rightDelimiter, other.rightDelimiter) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis);
+  }
+
+  @override
+  bool visitForStatement(ForStatement node) {
+    ForStatement other = _other as ForStatement;
+    return isEqualTokens(node.forKeyword, other.forKeyword) &&
+        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        isEqualNodes(node.variables, other.variables) &&
+        isEqualNodes(node.initialization, other.initialization) &&
+        isEqualTokens(node.leftSeparator, other.leftSeparator) &&
+        isEqualNodes(node.condition, other.condition) &&
+        isEqualTokens(node.rightSeparator, other.rightSeparator) &&
+        _isEqualNodeLists(node.updaters, other.updaters) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
+        isEqualNodes(node.body, other.body);
+  }
+
+  @override
+  bool visitFunctionDeclaration(FunctionDeclaration node) {
+    FunctionDeclaration other = _other as FunctionDeclaration;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.externalKeyword, other.externalKeyword) &&
+        isEqualNodes(node.returnType, other.returnType) &&
+        isEqualTokens(node.propertyKeyword, other.propertyKeyword) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualNodes(node.functionExpression, other.functionExpression);
+  }
+
+  @override
+  bool visitFunctionDeclarationStatement(FunctionDeclarationStatement node) {
+    FunctionDeclarationStatement other = _other as FunctionDeclarationStatement;
+    return isEqualNodes(node.functionDeclaration, other.functionDeclaration);
+  }
+
+  @override
+  bool visitFunctionExpression(FunctionExpression node) {
+    FunctionExpression other = _other as FunctionExpression;
+    return isEqualNodes(node.parameters, other.parameters) &&
+        isEqualNodes(node.body, other.body);
+  }
+
+  @override
+  bool visitFunctionExpressionInvocation(FunctionExpressionInvocation node) {
+    FunctionExpressionInvocation other = _other as FunctionExpressionInvocation;
+    return isEqualNodes(node.function, other.function) &&
+        isEqualNodes(node.argumentList, other.argumentList);
+  }
+
+  @override
+  bool visitFunctionTypeAlias(FunctionTypeAlias node) {
+    FunctionTypeAlias other = _other as FunctionTypeAlias;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.typedefKeyword, other.typedefKeyword) &&
+        isEqualNodes(node.returnType, other.returnType) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualNodes(node.typeParameters, other.typeParameters) &&
+        isEqualNodes(node.parameters, other.parameters) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
+    FunctionTypedFormalParameter other = _other as FunctionTypedFormalParameter;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualNodes(node.returnType, other.returnType) &&
+        isEqualNodes(node.identifier, other.identifier) &&
+        isEqualNodes(node.parameters, other.parameters);
+  }
+
+  @override
+  bool visitHideCombinator(HideCombinator node) {
+    HideCombinator other = _other as HideCombinator;
+    return isEqualTokens(node.keyword, other.keyword) &&
+        _isEqualNodeLists(node.hiddenNames, other.hiddenNames);
+  }
+
+  @override
+  bool visitIfStatement(IfStatement node) {
+    IfStatement other = _other as IfStatement;
+    return isEqualTokens(node.ifKeyword, other.ifKeyword) &&
+        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        isEqualNodes(node.condition, other.condition) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
+        isEqualNodes(node.thenStatement, other.thenStatement) &&
+        isEqualTokens(node.elseKeyword, other.elseKeyword) &&
+        isEqualNodes(node.elseStatement, other.elseStatement);
+  }
+
+  @override
+  bool visitImplementsClause(ImplementsClause node) {
+    ImplementsClause other = _other as ImplementsClause;
+    return isEqualTokens(node.implementsKeyword, other.implementsKeyword) &&
+        _isEqualNodeLists(node.interfaces, other.interfaces);
+  }
+
+  @override
+  bool visitImportDirective(ImportDirective node) {
+    ImportDirective other = _other as ImportDirective;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.keyword, other.keyword) &&
+        isEqualNodes(node.uri, other.uri) &&
+        isEqualTokens(node.deferredKeyword, other.deferredKeyword) &&
+        isEqualTokens(node.asKeyword, other.asKeyword) &&
+        isEqualNodes(node.prefix, other.prefix) &&
+        _isEqualNodeLists(node.combinators, other.combinators) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitIndexExpression(IndexExpression node) {
+    IndexExpression other = _other as IndexExpression;
+    return isEqualNodes(node.target, other.target) &&
+        isEqualTokens(node.leftBracket, other.leftBracket) &&
+        isEqualNodes(node.index, other.index) &&
+        isEqualTokens(node.rightBracket, other.rightBracket);
+  }
+
+  @override
+  bool visitInstanceCreationExpression(InstanceCreationExpression node) {
+    InstanceCreationExpression other = _other as InstanceCreationExpression;
+    return isEqualTokens(node.keyword, other.keyword) &&
+        isEqualNodes(node.constructorName, other.constructorName) &&
+        isEqualNodes(node.argumentList, other.argumentList);
+  }
+
+  @override
+  bool visitIntegerLiteral(IntegerLiteral node) {
+    IntegerLiteral other = _other as IntegerLiteral;
+    return isEqualTokens(node.literal, other.literal) &&
+        (node.value == other.value);
+  }
+
+  @override
+  bool visitInterpolationExpression(InterpolationExpression node) {
+    InterpolationExpression other = _other as InterpolationExpression;
+    return isEqualTokens(node.leftBracket, other.leftBracket) &&
+        isEqualNodes(node.expression, other.expression) &&
+        isEqualTokens(node.rightBracket, other.rightBracket);
+  }
+
+  @override
+  bool visitInterpolationString(InterpolationString node) {
+    InterpolationString other = _other as InterpolationString;
+    return isEqualTokens(node.contents, other.contents) &&
+        node.value == other.value;
+  }
+
+  @override
+  bool visitIsExpression(IsExpression node) {
+    IsExpression other = _other as IsExpression;
+    return isEqualNodes(node.expression, other.expression) &&
+        isEqualTokens(node.isOperator, other.isOperator) &&
+        isEqualTokens(node.notOperator, other.notOperator) &&
+        isEqualNodes(node.type, other.type);
+  }
+
+  @override
+  bool visitLabel(Label node) {
+    Label other = _other as Label;
+    return isEqualNodes(node.label, other.label) &&
+        isEqualTokens(node.colon, other.colon);
+  }
+
+  @override
+  bool visitLabeledStatement(LabeledStatement node) {
+    LabeledStatement other = _other as LabeledStatement;
+    return _isEqualNodeLists(node.labels, other.labels) &&
+        isEqualNodes(node.statement, other.statement);
+  }
+
+  @override
+  bool visitLibraryDirective(LibraryDirective node) {
+    LibraryDirective other = _other as LibraryDirective;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.libraryKeyword, other.libraryKeyword) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitLibraryIdentifier(LibraryIdentifier node) {
+    LibraryIdentifier other = _other as LibraryIdentifier;
+    return _isEqualNodeLists(node.components, other.components);
+  }
+
+  @override
+  bool visitListLiteral(ListLiteral node) {
+    ListLiteral other = _other as ListLiteral;
+    return isEqualTokens(node.constKeyword, other.constKeyword) &&
+        isEqualNodes(node.typeArguments, other.typeArguments) &&
+        isEqualTokens(node.leftBracket, other.leftBracket) &&
+        _isEqualNodeLists(node.elements, other.elements) &&
+        isEqualTokens(node.rightBracket, other.rightBracket);
+  }
+
+  @override
+  bool visitMapLiteral(MapLiteral node) {
+    MapLiteral other = _other as MapLiteral;
+    return isEqualTokens(node.constKeyword, other.constKeyword) &&
+        isEqualNodes(node.typeArguments, other.typeArguments) &&
+        isEqualTokens(node.leftBracket, other.leftBracket) &&
+        _isEqualNodeLists(node.entries, other.entries) &&
+        isEqualTokens(node.rightBracket, other.rightBracket);
+  }
+
+  @override
+  bool visitMapLiteralEntry(MapLiteralEntry node) {
+    MapLiteralEntry other = _other as MapLiteralEntry;
+    return isEqualNodes(node.key, other.key) &&
+        isEqualTokens(node.separator, other.separator) &&
+        isEqualNodes(node.value, other.value);
+  }
+
+  @override
+  bool visitMethodDeclaration(MethodDeclaration node) {
+    MethodDeclaration other = _other as MethodDeclaration;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.externalKeyword, other.externalKeyword) &&
+        isEqualTokens(node.modifierKeyword, other.modifierKeyword) &&
+        isEqualNodes(node.returnType, other.returnType) &&
+        isEqualTokens(node.propertyKeyword, other.propertyKeyword) &&
+        isEqualTokens(node.propertyKeyword, other.propertyKeyword) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualNodes(node.parameters, other.parameters) &&
+        isEqualNodes(node.body, other.body);
+  }
+
+  @override
+  bool visitMethodInvocation(MethodInvocation node) {
+    MethodInvocation other = _other as MethodInvocation;
+    return isEqualNodes(node.target, other.target) &&
+        isEqualTokens(node.operator, other.operator) &&
+        isEqualNodes(node.methodName, other.methodName) &&
+        isEqualNodes(node.argumentList, other.argumentList);
+  }
+
+  @override
+  bool visitNamedExpression(NamedExpression node) {
+    NamedExpression other = _other as NamedExpression;
+    return isEqualNodes(node.name, other.name) &&
+        isEqualNodes(node.expression, other.expression);
+  }
+
+  @override
+  bool visitNativeClause(NativeClause node) {
+    NativeClause other = _other as NativeClause;
+    return isEqualTokens(node.nativeKeyword, other.nativeKeyword) &&
+        isEqualNodes(node.name, other.name);
+  }
+
+  @override
+  bool visitNativeFunctionBody(NativeFunctionBody node) {
+    NativeFunctionBody other = _other as NativeFunctionBody;
+    return isEqualTokens(node.nativeKeyword, other.nativeKeyword) &&
+        isEqualNodes(node.stringLiteral, other.stringLiteral) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitNullLiteral(NullLiteral node) {
+    NullLiteral other = _other as NullLiteral;
+    return isEqualTokens(node.literal, other.literal);
+  }
+
+  @override
+  bool visitParenthesizedExpression(ParenthesizedExpression node) {
+    ParenthesizedExpression other = _other as ParenthesizedExpression;
+    return isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        isEqualNodes(node.expression, other.expression) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis);
+  }
+
+  @override
+  bool visitPartDirective(PartDirective node) {
+    PartDirective other = _other as PartDirective;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.partKeyword, other.partKeyword) &&
+        isEqualNodes(node.uri, other.uri) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitPartOfDirective(PartOfDirective node) {
+    PartOfDirective other = _other as PartOfDirective;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.partKeyword, other.partKeyword) &&
+        isEqualTokens(node.ofKeyword, other.ofKeyword) &&
+        isEqualNodes(node.libraryName, other.libraryName) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitPostfixExpression(PostfixExpression node) {
+    PostfixExpression other = _other as PostfixExpression;
+    return isEqualNodes(node.operand, other.operand) &&
+        isEqualTokens(node.operator, other.operator);
+  }
+
+  @override
+  bool visitPrefixedIdentifier(PrefixedIdentifier node) {
+    PrefixedIdentifier other = _other as PrefixedIdentifier;
+    return isEqualNodes(node.prefix, other.prefix) &&
+        isEqualTokens(node.period, other.period) &&
+        isEqualNodes(node.identifier, other.identifier);
+  }
+
+  @override
+  bool visitPrefixExpression(PrefixExpression node) {
+    PrefixExpression other = _other as PrefixExpression;
+    return isEqualTokens(node.operator, other.operator) &&
+        isEqualNodes(node.operand, other.operand);
+  }
+
+  @override
+  bool visitPropertyAccess(PropertyAccess node) {
+    PropertyAccess other = _other as PropertyAccess;
+    return isEqualNodes(node.target, other.target) &&
+        isEqualTokens(node.operator, other.operator) &&
+        isEqualNodes(node.propertyName, other.propertyName);
+  }
+
+  @override
+  bool visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) {
+    RedirectingConstructorInvocation other =
+        _other as RedirectingConstructorInvocation;
+    return isEqualTokens(node.thisKeyword, other.thisKeyword) &&
+        isEqualTokens(node.period, other.period) &&
+        isEqualNodes(node.constructorName, other.constructorName) &&
+        isEqualNodes(node.argumentList, other.argumentList);
+  }
+
+  @override
+  bool visitRethrowExpression(RethrowExpression node) {
+    RethrowExpression other = _other as RethrowExpression;
+    return isEqualTokens(node.rethrowKeyword, other.rethrowKeyword);
+  }
+
+  @override
+  bool visitReturnStatement(ReturnStatement node) {
+    ReturnStatement other = _other as ReturnStatement;
+    return isEqualTokens(node.returnKeyword, other.returnKeyword) &&
+        isEqualNodes(node.expression, other.expression) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitScriptTag(ScriptTag node) {
+    ScriptTag other = _other as ScriptTag;
+    return isEqualTokens(node.scriptTag, other.scriptTag);
+  }
+
+  @override
+  bool visitShowCombinator(ShowCombinator node) {
+    ShowCombinator other = _other as ShowCombinator;
+    return isEqualTokens(node.keyword, other.keyword) &&
+        _isEqualNodeLists(node.shownNames, other.shownNames);
+  }
+
+  @override
+  bool visitSimpleFormalParameter(SimpleFormalParameter node) {
+    SimpleFormalParameter other = _other as SimpleFormalParameter;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.keyword, other.keyword) &&
+        isEqualNodes(node.type, other.type) &&
+        isEqualNodes(node.identifier, other.identifier);
+  }
+
+  @override
+  bool visitSimpleIdentifier(SimpleIdentifier node) {
+    SimpleIdentifier other = _other as SimpleIdentifier;
+    return isEqualTokens(node.token, other.token);
+  }
+
+  @override
+  bool visitSimpleStringLiteral(SimpleStringLiteral node) {
+    SimpleStringLiteral other = _other as SimpleStringLiteral;
+    return isEqualTokens(node.literal, other.literal) &&
+        (node.value == other.value);
+  }
+
+  @override
+  bool visitStringInterpolation(StringInterpolation node) {
+    StringInterpolation other = _other as StringInterpolation;
+    return _isEqualNodeLists(node.elements, other.elements);
+  }
+
+  @override
+  bool visitSuperConstructorInvocation(SuperConstructorInvocation node) {
+    SuperConstructorInvocation other = _other as SuperConstructorInvocation;
+    return isEqualTokens(node.superKeyword, other.superKeyword) &&
+        isEqualTokens(node.period, other.period) &&
+        isEqualNodes(node.constructorName, other.constructorName) &&
+        isEqualNodes(node.argumentList, other.argumentList);
+  }
+
+  @override
+  bool visitSuperExpression(SuperExpression node) {
+    SuperExpression other = _other as SuperExpression;
+    return isEqualTokens(node.superKeyword, other.superKeyword);
+  }
+
+  @override
+  bool visitSwitchCase(SwitchCase node) {
+    SwitchCase other = _other as SwitchCase;
+    return _isEqualNodeLists(node.labels, other.labels) &&
+        isEqualTokens(node.keyword, other.keyword) &&
+        isEqualNodes(node.expression, other.expression) &&
+        isEqualTokens(node.colon, other.colon) &&
+        _isEqualNodeLists(node.statements, other.statements);
+  }
+
+  @override
+  bool visitSwitchDefault(SwitchDefault node) {
+    SwitchDefault other = _other as SwitchDefault;
+    return _isEqualNodeLists(node.labels, other.labels) &&
+        isEqualTokens(node.keyword, other.keyword) &&
+        isEqualTokens(node.colon, other.colon) &&
+        _isEqualNodeLists(node.statements, other.statements);
+  }
+
+  @override
+  bool visitSwitchStatement(SwitchStatement node) {
+    SwitchStatement other = _other as SwitchStatement;
+    return isEqualTokens(node.switchKeyword, other.switchKeyword) &&
+        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        isEqualNodes(node.expression, other.expression) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
+        isEqualTokens(node.leftBracket, other.leftBracket) &&
+        _isEqualNodeLists(node.members, other.members) &&
+        isEqualTokens(node.rightBracket, other.rightBracket);
+  }
+
+  @override
+  bool visitSymbolLiteral(SymbolLiteral node) {
+    SymbolLiteral other = _other as SymbolLiteral;
+    return isEqualTokens(node.poundSign, other.poundSign) &&
+        _isEqualTokenLists(node.components, other.components);
+  }
+
+  @override
+  bool visitThisExpression(ThisExpression node) {
+    ThisExpression other = _other as ThisExpression;
+    return isEqualTokens(node.thisKeyword, other.thisKeyword);
+  }
+
+  @override
+  bool visitThrowExpression(ThrowExpression node) {
+    ThrowExpression other = _other as ThrowExpression;
+    return isEqualTokens(node.throwKeyword, other.throwKeyword) &&
+        isEqualNodes(node.expression, other.expression);
+  }
+
+  @override
+  bool visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
+    TopLevelVariableDeclaration other = _other as TopLevelVariableDeclaration;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualNodes(node.variables, other.variables) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitTryStatement(TryStatement node) {
+    TryStatement other = _other as TryStatement;
+    return isEqualTokens(node.tryKeyword, other.tryKeyword) &&
+        isEqualNodes(node.body, other.body) &&
+        _isEqualNodeLists(node.catchClauses, other.catchClauses) &&
+        isEqualTokens(node.finallyKeyword, other.finallyKeyword) &&
+        isEqualNodes(node.finallyBlock, other.finallyBlock);
+  }
+
+  @override
+  bool visitTypeArgumentList(TypeArgumentList node) {
+    TypeArgumentList other = _other as TypeArgumentList;
+    return isEqualTokens(node.leftBracket, other.leftBracket) &&
+        _isEqualNodeLists(node.arguments, other.arguments) &&
+        isEqualTokens(node.rightBracket, other.rightBracket);
+  }
+
+  @override
+  bool visitTypeName(TypeName node) {
+    TypeName other = _other as TypeName;
+    return isEqualNodes(node.name, other.name) &&
+        isEqualNodes(node.typeArguments, other.typeArguments);
+  }
+
+  @override
+  bool visitTypeParameter(TypeParameter node) {
+    TypeParameter other = _other as TypeParameter;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualTokens(node.extendsKeyword, other.extendsKeyword) &&
+        isEqualNodes(node.bound, other.bound);
+  }
+
+  @override
+  bool visitTypeParameterList(TypeParameterList node) {
+    TypeParameterList other = _other as TypeParameterList;
+    return isEqualTokens(node.leftBracket, other.leftBracket) &&
+        _isEqualNodeLists(node.typeParameters, other.typeParameters) &&
+        isEqualTokens(node.rightBracket, other.rightBracket);
+  }
+
+  @override
+  bool visitVariableDeclaration(VariableDeclaration node) {
+    VariableDeclaration other = _other as VariableDeclaration;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualNodes(node.name, other.name) &&
+        isEqualTokens(node.equals, other.equals) &&
+        isEqualNodes(node.initializer, other.initializer);
+  }
+
+  @override
+  bool visitVariableDeclarationList(VariableDeclarationList node) {
+    VariableDeclarationList other = _other as VariableDeclarationList;
+    return isEqualNodes(
+            node.documentationComment, other.documentationComment) &&
+        _isEqualNodeLists(node.metadata, other.metadata) &&
+        isEqualTokens(node.keyword, other.keyword) &&
+        isEqualNodes(node.type, other.type) &&
+        _isEqualNodeLists(node.variables, other.variables);
+  }
+
+  @override
+  bool visitVariableDeclarationStatement(VariableDeclarationStatement node) {
+    VariableDeclarationStatement other = _other as VariableDeclarationStatement;
+    return isEqualNodes(node.variables, other.variables) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  @override
+  bool visitWhileStatement(WhileStatement node) {
+    WhileStatement other = _other as WhileStatement;
+    return isEqualTokens(node.whileKeyword, other.whileKeyword) &&
+        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
+        isEqualNodes(node.condition, other.condition) &&
+        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
+        isEqualNodes(node.body, other.body);
+  }
+
+  @override
+  bool visitWithClause(WithClause node) {
+    WithClause other = _other as WithClause;
+    return isEqualTokens(node.withKeyword, other.withKeyword) &&
+        _isEqualNodeLists(node.mixinTypes, other.mixinTypes);
+  }
+
+  @override
+  bool visitYieldStatement(YieldStatement node) {
+    YieldStatement other = _other as YieldStatement;
+    return isEqualTokens(node.yieldKeyword, other.yieldKeyword) &&
+        isEqualNodes(node.expression, other.expression) &&
+        isEqualTokens(node.semicolon, other.semicolon);
+  }
+
+  /**
+   * Return `true` if the [first] and [second] lists of AST nodes have the same
+   * size and corresponding elements are equal.
+   */
+  bool _isEqualNodeLists(NodeList first, NodeList second) {
+    if (first == null) {
+      return second == null;
+    } else if (second == null) {
+      return false;
+    }
+    int size = first.length;
+    if (second.length != size) {
+      return false;
+    }
+    for (int i = 0; i < size; i++) {
+      if (!isEqualNodes(first[i], second[i])) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  /**
+   * Return `true` if the [first] and [second] lists of tokens have the same
+   * length and corresponding elements are equal.
+   */
+  bool _isEqualTokenLists(List<Token> first, List<Token> second) {
+    int length = first.length;
+    if (second.length != length) {
+      return false;
+    }
+    for (int i = 0; i < length; i++) {
+      if (!isEqualTokens(first[i], second[i])) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  /**
+   * Return `true` if the [first] and [second] nodes are equal.
+   */
+  static bool equalNodes(AstNode first, AstNode second) {
+    AstComparator comparator = new AstComparator();
+    return comparator.isEqualNodes(first, second);
+  }
+}
+
+/**
+ * A node in the AST structure for a Dart program.
+ */
+abstract class AstNode {
+  /**
+   * An empty list of AST nodes.
+   */
+  @deprecated // Use "AstNode.EMPTY_LIST"
+  static const List<AstNode> EMPTY_ARRAY = EMPTY_LIST;
+
+  /**
+   * An empty list of AST nodes.
+   */
+  static const List<AstNode> EMPTY_LIST = const <AstNode>[];
+
+  /**
+   * A comparator that can be used to sort AST nodes in lexical order. In other
+   * words, `compare` will return a negative value if the offset of the first
+   * node is less than the offset of the second node, zero (0) if the nodes have
+   * the same offset, and a positive value if the offset of the first node is
+   * greater than the offset of the second node.
+   */
+  static Comparator<AstNode> LEXICAL_ORDER =
+      (AstNode first, AstNode second) => first.offset - second.offset;
+
+  /**
+   * The parent of the node, or `null` if the node is the root of an AST
+   * structure.
+   */
+  AstNode _parent;
+
+  /**
+   * A table mapping the names of properties to their values, or `null` if this
+   * node does not have any properties associated with it.
+   */
+  Map<String, Object> _propertyMap;
+
+  /**
+   * Return the first token included in this node's source range.
+   */
+  Token get beginToken;
+
+  /**
+   * Iterate through all the entities (either AST nodes or tokens) which make
+   * up the contents of this node, including doc comments but excluding other
+   * comments.
+   */
+  Iterable /*<AstNode | Token>*/ get childEntities;
+
+  /**
+   * Return the offset of the character immediately following the last character
+   * of this node's source range. This is equivalent to
+   * `node.getOffset() + node.getLength()`. For a compilation unit this will be
+   * equal to the length of the unit's source. For synthetic nodes this will be
+   * equivalent to the node's offset (because the length is zero (0) by
+   * definition).
+   */
+  int get end => offset + length;
+
+  /**
+   * Return the last token included in this node's source range.
+   */
+  Token get endToken;
+
+  /**
+   * Return `true` if this node is a synthetic node. A synthetic node is a node
+   * that was introduced by the parser in order to recover from an error in the
+   * code. Synthetic nodes always have a length of zero (`0`).
+   */
+  bool get isSynthetic => false;
+
+  /**
+   * Return the number of characters in the node's source range.
+   */
+  int get length {
+    Token beginToken = this.beginToken;
+    Token endToken = this.endToken;
+    if (beginToken == null || endToken == null) {
+      return -1;
+    }
+    return endToken.offset + endToken.length - beginToken.offset;
+  }
+
+  /**
+   * Return the offset from the beginning of the file to the first character in
+   * the node's source range.
+   */
+  int get offset {
+    Token beginToken = this.beginToken;
+    if (beginToken == null) {
+      return -1;
+    }
+    return beginToken.offset;
+  }
+
+  /**
+   * Return this node's parent node, or `null` if this node is the root of an
+   * AST structure.
+   *
+   * Note that the relationship between an AST node and its parent node may
+   * change over the lifetime of a node.
+   */
+  AstNode get parent => _parent;
+
+  /**
+   * Set the parent of this node to the [newParent].
+   */
+  @deprecated // Never intended for public use.
+  void set parent(AstNode newParent) {
+    _parent = newParent;
+  }
+
+  /**
+   * Return the node at the root of this node's AST structure. Note that this
+   * method's performance is linear with respect to the depth of the node in the
+   * AST structure (O(depth)).
+   */
+  AstNode get root {
+    AstNode root = this;
+    AstNode parent = this.parent;
+    while (parent != null) {
+      root = parent;
+      parent = root.parent;
+    }
+    return root;
+  }
+
+  /**
+   * Use the given [visitor] to visit this node. Return the value returned by
+   * the visitor as a result of visiting this node.
+   */
+  /* <E> E */ accept(AstVisitor /*<E>*/ visitor);
+
+  /**
+   * Make this node the parent of the given [child] node. Return the child node.
+   */
+  @deprecated // Never intended for public use.
+  AstNode becomeParentOf(AstNode child) {
+    return _becomeParentOf(child);
+  }
+
+  /**
+   * Return the most immediate ancestor of this node for which the [predicate]
+   * returns `true`, or `null` if there is no such ancestor. Note that this node
+   * will never be returned.
+   */
+  AstNode getAncestor(Predicate<AstNode> predicate) {
+    // TODO(brianwilkerson) It is a bug that this method can return `this`.
+    AstNode node = this;
+    while (node != null && !predicate(node)) {
+      node = node.parent;
+    }
+    return node;
+  }
+
+  /**
+   * Return the value of the property with the given [name], or `null` if this
+   * node does not have a property with the given name.
+   */
+  Object getProperty(String name) {
+    if (_propertyMap == null) {
+      return null;
+    }
+    return _propertyMap[name];
+  }
+
+  /**
+   * If the given [child] is not `null`, use the given [visitor] to visit it.
+   */
+  @deprecated // Never intended for public use.
+  void safelyVisitChild(AstNode child, AstVisitor visitor) {
+    if (child != null) {
+      child.accept(visitor);
+    }
+  }
+
+  /**
+   * Set the value of the property with the given [name] to the given [value].
+   * If the value is `null`, the property will effectively be removed.
+   */
+  void setProperty(String name, Object value) {
+    if (value == null) {
+      if (_propertyMap != null) {
+        _propertyMap.remove(name);
+        if (_propertyMap.isEmpty) {
+          _propertyMap = null;
+        }
+      }
+    } else {
+      if (_propertyMap == null) {
+        _propertyMap = new HashMap<String, Object>();
+      }
+      _propertyMap[name] = value;
+    }
+  }
+
+  /**
+   * Return a textual description of this node in a form approximating valid
+   * source. The returned string will not be valid source primarily in the case
+   * where the node itself is not well-formed.
+   */
+  String toSource() {
+    PrintStringWriter writer = new PrintStringWriter();
+    accept(new ToSourceVisitor(writer));
+    return writer.toString();
+  }
+
+  @override
+  String toString() => toSource();
+
+  /**
+   * Use the given [visitor] to visit all of the children of this node. The
+   * children will be visited in lexical order.
+   */
+  void visitChildren(AstVisitor visitor);
+
+  /**
+   * Make this node the parent of the given [child] node. Return the child node.
+   */
+  AstNode _becomeParentOf(AstNode child) {
+    if (child != null) {
+      child._parent = this;
+    }
+    return child;
+  }
+
+  /**
+   * If the given [child] is not `null`, use the given [visitor] to visit it.
+   */
+  void _safelyVisitChild(AstNode child, AstVisitor visitor) {
+    if (child != null) {
+      child.accept(visitor);
+    }
+  }
+}
+
+/**
+ * An object that can be used to visit an AST structure.
+ */
+abstract class AstVisitor<R> {
+  R visitAdjacentStrings(AdjacentStrings node);
+
+  R visitAnnotation(Annotation node);
+
+  R visitArgumentList(ArgumentList node);
+
+  R visitAsExpression(AsExpression node);
+
+  R visitAssertStatement(AssertStatement assertStatement);
+
+  R visitAssignmentExpression(AssignmentExpression node);
+
+  R visitAwaitExpression(AwaitExpression node);
+
+  R visitBinaryExpression(BinaryExpression node);
+
+  R visitBlock(Block node);
+
+  R visitBlockFunctionBody(BlockFunctionBody node);
+
+  R visitBooleanLiteral(BooleanLiteral node);
+
+  R visitBreakStatement(BreakStatement node);
+
+  R visitCascadeExpression(CascadeExpression node);
+
+  R visitCatchClause(CatchClause node);
+
+  R visitClassDeclaration(ClassDeclaration node);
+
+  R visitClassTypeAlias(ClassTypeAlias node);
+
+  R visitComment(Comment node);
+
+  R visitCommentReference(CommentReference node);
+
+  R visitCompilationUnit(CompilationUnit node);
+
+  R visitConditionalExpression(ConditionalExpression node);
+
+  R visitConstructorDeclaration(ConstructorDeclaration node);
+
+  R visitConstructorFieldInitializer(ConstructorFieldInitializer node);
+
+  R visitConstructorName(ConstructorName node);
+
+  R visitContinueStatement(ContinueStatement node);
+
+  R visitDeclaredIdentifier(DeclaredIdentifier node);
+
+  R visitDefaultFormalParameter(DefaultFormalParameter node);
+
+  R visitDoStatement(DoStatement node);
+
+  R visitDoubleLiteral(DoubleLiteral node);
+
+  R visitEmptyFunctionBody(EmptyFunctionBody node);
+
+  R visitEmptyStatement(EmptyStatement node);
+
+  R visitEnumConstantDeclaration(EnumConstantDeclaration node);
+
+  R visitEnumDeclaration(EnumDeclaration node);
+
+  R visitExportDirective(ExportDirective node);
+
+  R visitExpressionFunctionBody(ExpressionFunctionBody node);
+
+  R visitExpressionStatement(ExpressionStatement node);
+
+  R visitExtendsClause(ExtendsClause node);
+
+  R visitFieldDeclaration(FieldDeclaration node);
+
+  R visitFieldFormalParameter(FieldFormalParameter node);
+
+  R visitForEachStatement(ForEachStatement node);
+
+  R visitFormalParameterList(FormalParameterList node);
+
+  R visitForStatement(ForStatement node);
+
+  R visitFunctionDeclaration(FunctionDeclaration node);
+
+  R visitFunctionDeclarationStatement(FunctionDeclarationStatement node);
+
+  R visitFunctionExpression(FunctionExpression node);
+
+  R visitFunctionExpressionInvocation(FunctionExpressionInvocation node);
+
+  R visitFunctionTypeAlias(FunctionTypeAlias functionTypeAlias);
+
+  R visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node);
+
+  R visitHideCombinator(HideCombinator node);
+
+  R visitIfStatement(IfStatement node);
+
+  R visitImplementsClause(ImplementsClause node);
+
+  R visitImportDirective(ImportDirective node);
+
+  R visitIndexExpression(IndexExpression node);
+
+  R visitInstanceCreationExpression(InstanceCreationExpression node);
+
+  R visitIntegerLiteral(IntegerLiteral node);
+
+  R visitInterpolationExpression(InterpolationExpression node);
+
+  R visitInterpolationString(InterpolationString node);
+
+  R visitIsExpression(IsExpression node);
+
+  R visitLabel(Label node);
+
+  R visitLabeledStatement(LabeledStatement node);
+
+  R visitLibraryDirective(LibraryDirective node);
+
+  R visitLibraryIdentifier(LibraryIdentifier node);
+
+  R visitListLiteral(ListLiteral node);
+
+  R visitMapLiteral(MapLiteral node);
+
+  R visitMapLiteralEntry(MapLiteralEntry node);
+
+  R visitMethodDeclaration(MethodDeclaration node);
+
+  R visitMethodInvocation(MethodInvocation node);
+
+  R visitNamedExpression(NamedExpression node);
+
+  R visitNativeClause(NativeClause node);
+
+  R visitNativeFunctionBody(NativeFunctionBody node);
+
+  R visitNullLiteral(NullLiteral node);
+
+  R visitParenthesizedExpression(ParenthesizedExpression node);
+
+  R visitPartDirective(PartDirective node);
+
+  R visitPartOfDirective(PartOfDirective node);
+
+  R visitPostfixExpression(PostfixExpression node);
+
+  R visitPrefixedIdentifier(PrefixedIdentifier node);
+
+  R visitPrefixExpression(PrefixExpression node);
+
+  R visitPropertyAccess(PropertyAccess node);
+
+  R visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node);
+
+  R visitRethrowExpression(RethrowExpression node);
+
+  R visitReturnStatement(ReturnStatement node);
+
+  R visitScriptTag(ScriptTag node);
+
+  R visitShowCombinator(ShowCombinator node);
+
+  R visitSimpleFormalParameter(SimpleFormalParameter node);
+
+  R visitSimpleIdentifier(SimpleIdentifier node);
+
+  R visitSimpleStringLiteral(SimpleStringLiteral node);
+
+  R visitStringInterpolation(StringInterpolation node);
+
+  R visitSuperConstructorInvocation(SuperConstructorInvocation node);
+
+  R visitSuperExpression(SuperExpression node);
+
+  R visitSwitchCase(SwitchCase node);
+
+  R visitSwitchDefault(SwitchDefault node);
+
+  R visitSwitchStatement(SwitchStatement node);
+
+  R visitSymbolLiteral(SymbolLiteral node);
+
+  R visitThisExpression(ThisExpression node);
+
+  R visitThrowExpression(ThrowExpression node);
+
+  R visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node);
+
+  R visitTryStatement(TryStatement node);
+
+  R visitTypeArgumentList(TypeArgumentList node);
+
+  R visitTypeName(TypeName node);
+
+  R visitTypeParameter(TypeParameter node);
+
+  R visitTypeParameterList(TypeParameterList node);
+
+  R visitVariableDeclaration(VariableDeclaration node);
+
+  R visitVariableDeclarationList(VariableDeclarationList node);
+
+  R visitVariableDeclarationStatement(VariableDeclarationStatement node);
+
+  R visitWhileStatement(WhileStatement node);
+
+  R visitWithClause(WithClause node);
+
+  R visitYieldStatement(YieldStatement node);
+}
+
+/**
+ * An await expression.
+ *
+ * > awaitExpression ::=
+ * >     'await' [Expression]
+ */
+class AwaitExpression extends Expression {
+  /**
+   * The 'await' keyword.
+   */
+  Token awaitKeyword;
+
+  /**
+   * The expression whose value is being waited on.
+   */
+  Expression _expression;
+
+  /**
+   * Initialize a newly created await expression.
+   */
+  AwaitExpression(this.awaitKeyword, Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get beginToken {
+    if (awaitKeyword != null) {
+      return awaitKeyword;
+    }
+    return _expression.beginToken;
+  }
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(awaitKeyword)..add(_expression);
+
+  @override
+  Token get endToken => _expression.endToken;
+
+  /**
+   * Return the expression whose value is being waited on.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression whose value is being waited on to the given [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  int get precedence => 0;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitAwaitExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+  }
+}
+
+/**
+ * A binary (infix) expression.
+ *
+ * > binaryExpression ::=
+ * >     [Expression] [Token] [Expression]
+ */
+class BinaryExpression extends Expression {
+  /**
+   * The expression used to compute the left operand.
+   */
+  Expression _leftOperand;
+
+  /**
+   * The binary operator being applied.
+   */
+  Token operator;
+
+  /**
+   * The expression used to compute the right operand.
+   */
+  Expression _rightOperand;
+
+  /**
+   * The element associated with the operator based on the static type of the
+   * left operand, or `null` if the AST structure has not been resolved, if the
+   * operator is not user definable, or if the operator could not be resolved.
+   */
+  MethodElement staticElement;
+
+  /**
+   * The element associated with the operator based on the propagated type of
+   * the left operand, or `null` if the AST structure has not been resolved, if
+   * the operator is not user definable, or if the operator could not be
+   * resolved.
+   */
+  MethodElement propagatedElement;
+
+  /**
+   * Initialize a newly created binary expression.
+   */
+  BinaryExpression(
+      Expression leftOperand, this.operator, Expression rightOperand) {
+    _leftOperand = _becomeParentOf(leftOperand);
+    _rightOperand = _becomeParentOf(rightOperand);
+  }
+
+  @override
+  Token get beginToken => _leftOperand.beginToken;
+
+  /**
+   * Return the best element available for this operator. If resolution was able
+   * to find a better element based on type propagation, that element will be
+   * returned. Otherwise, the element found using the result of static analysis
+   * will be returned. If resolution has not been performed, then `null` will be
+   * returned.
+   */
+  MethodElement get bestElement {
+    MethodElement element = propagatedElement;
+    if (element == null) {
+      element = staticElement;
+    }
+    return element;
+  }
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_leftOperand)..add(operator)..add(_rightOperand);
+
+  @override
+  Token get endToken => _rightOperand.endToken;
+
+  /**
+   * Return the expression used to compute the left operand.
+   */
+  Expression get leftOperand => _leftOperand;
+
+  /**
+   * Set the expression used to compute the left operand to the given
+   * [expression].
+   */
+  void set leftOperand(Expression expression) {
+    _leftOperand = _becomeParentOf(expression);
+  }
+
+  @override
+  int get precedence => operator.type.precedence;
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on propagated type information, then return the parameter
+   * element representing the parameter to which the value of the right operand
+   * will be bound. Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.propagatedParameterElement"
+  ParameterElement get propagatedParameterElementForRightOperand {
+    return _propagatedParameterElementForRightOperand;
+  }
+
+  /**
+   * Return the expression used to compute the right operand.
+   */
+  Expression get rightOperand => _rightOperand;
+
+  /**
+   * Set the expression used to compute the right operand to the given
+   * [expression].
+   */
+  void set rightOperand(Expression expression) {
+    _rightOperand = _becomeParentOf(expression);
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on static type information, then return the parameter element
+   * representing the parameter to which the value of the right operand will be
+   * bound. Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.staticParameterElement"
+  ParameterElement get staticParameterElementForRightOperand {
+    return _staticParameterElementForRightOperand;
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on propagated type information, then return the parameter
+   * element representing the parameter to which the value of the right operand
+   * will be bound. Otherwise, return `null`.
+   */
+  ParameterElement get _propagatedParameterElementForRightOperand {
+    if (propagatedElement == null) {
+      return null;
+    }
+    List<ParameterElement> parameters = propagatedElement.parameters;
+    if (parameters.length < 1) {
+      return null;
+    }
+    return parameters[0];
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on static type information, then return the parameter element
+   * representing the parameter to which the value of the right operand will be
+   * bound. Otherwise, return `null`.
+   */
+  ParameterElement get _staticParameterElementForRightOperand {
+    if (staticElement == null) {
+      return null;
+    }
+    List<ParameterElement> parameters = staticElement.parameters;
+    if (parameters.length < 1) {
+      return null;
+    }
+    return parameters[0];
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitBinaryExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_leftOperand, visitor);
+    _safelyVisitChild(_rightOperand, visitor);
+  }
+}
+
+/**
+ * A sequence of statements.
+ *
+ * > block ::=
+ * >     '{' statement* '}'
+ */
+class Block extends Statement {
+  /**
+   * The left curly bracket.
+   */
+  Token leftBracket;
+
+  /**
+   * The statements contained in the block.
+   */
+  NodeList<Statement> _statements;
+
+  /**
+   * The right curly bracket.
+   */
+  Token rightBracket;
+
+  /**
+   * Initialize a newly created block of code.
+   */
+  Block(this.leftBracket, List<Statement> statements, this.rightBracket) {
+    _statements = new NodeList<Statement>(this, statements);
+  }
+
+  @override
+  Token get beginToken => leftBracket;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(leftBracket)
+    ..addAll(_statements)
+    ..add(rightBracket);
+
+  @override
+  Token get endToken => rightBracket;
+
+  /**
+   * Return the statements contained in the block.
+   */
+  NodeList<Statement> get statements => _statements;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitBlock(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _statements.accept(visitor);
+  }
+}
+
+/**
+ * A function body that consists of a block of statements.
+ *
+ * > blockFunctionBody ::=
+ * >     ('async' | 'async' '*' | 'sync' '*')? [Block]
+ */
+class BlockFunctionBody extends FunctionBody {
+  /**
+   * The token representing the 'async' or 'sync' keyword, or `null` if there is
+   * no such keyword.
+   */
+  Token keyword;
+
+  /**
+   * The star optionally following the 'async' or 'sync' keyword, or `null` if
+   * there is wither no such keyword or no star.
+   */
+  Token star;
+
+  /**
+   * The block representing the body of the function.
+   */
+  Block _block;
+
+  /**
+   * Initialize a newly created function body consisting of a block of
+   * statements. The [keyword] can be `null` if there is no keyword specified
+   * for the block. The [star] can be `null` if there is no star following the
+   * keyword (and must be `null` if there is no keyword).
+   */
+  BlockFunctionBody(this.keyword, this.star, Block block) {
+    _block = _becomeParentOf(block);
+  }
+
+  @override
+  Token get beginToken => _block.beginToken;
+
+  /**
+   * Return the block representing the body of the function.
+   */
+  Block get block => _block;
+
+  /**
+   * Set the block representing the body of the function to the given [block].
+   */
+  void set block(Block block) {
+    _block = _becomeParentOf(block);
+  }
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(keyword)..add(star)..add(_block);
+
+  @override
+  Token get endToken => _block.endToken;
+
+  @override
+  bool get isAsynchronous => keyword != null && keyword.lexeme == Parser.ASYNC;
+
+  @override
+  bool get isGenerator => star != null;
+
+  @override
+  bool get isSynchronous => keyword == null || keyword.lexeme != Parser.ASYNC;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitBlockFunctionBody(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_block, visitor);
+  }
+}
+
+/**
+ * A boolean literal expression.
+ *
+ * > booleanLiteral ::=
+ * >     'false' | 'true'
+ */
+class BooleanLiteral extends Literal {
+  /**
+   * The token representing the literal.
+   */
+  Token literal;
+
+  /**
+   * The value of the literal.
+   */
+  bool value = false;
+
+  /**
+   * Initialize a newly created boolean literal.
+   */
+  BooleanLiteral(this.literal, this.value);
+
+  @override
+  Token get beginToken => literal;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(literal);
+
+  @override
+  Token get endToken => literal;
+
+  @override
+  bool get isSynthetic => literal.isSynthetic;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitBooleanLiteral(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+}
+
+/**
+ * An AST visitor that will recursively visit all of the nodes in an AST
+ * structure, similar to [GeneralizingAstVisitor]. This visitor uses a
+ * breadth-first ordering rather than the depth-first ordering of
+ * [GeneralizingAstVisitor].
+ *
+ * Subclasses that override a visit method must either invoke the overridden
+ * visit method or explicitly invoke the more general visit method. Failure to
+ * do so will cause the visit methods for superclasses of the node to not be
+ * invoked and will cause the children of the visited node to not be visited.
+ *
+ * In addition, subclasses should <b>not</b> explicitly visit the children of a
+ * node, but should ensure that the method [visitNode] is used to visit the
+ * children (either directly or indirectly). Failure to do will break the order
+ * in which nodes are visited.
+ */
+class BreadthFirstVisitor<R> extends GeneralizingAstVisitor<R> {
+  /**
+   * A queue holding the nodes that have not yet been visited in the order in
+   * which they ought to be visited.
+   */
+  Queue<AstNode> _queue = new Queue<AstNode>();
+
+  /**
+   * A visitor, used to visit the children of the current node, that will add
+   * the nodes it visits to the [_queue].
+   */
+  GeneralizingAstVisitor<Object> _childVisitor;
+
+  /**
+   * Initialize a newly created visitor.
+   */
+  BreadthFirstVisitor() {
+    _childVisitor = new GeneralizingAstVisitor_BreadthFirstVisitor(this);
+  }
+
+  /**
+   * Visit all nodes in the tree starting at the given [root] node, in
+   * breadth-first order.
+   */
+  void visitAllNodes(AstNode root) {
+    _queue.add(root);
+    while (!_queue.isEmpty) {
+      AstNode next = _queue.removeFirst();
+      next.accept(this);
+    }
+  }
+
+  @override
+  R visitNode(AstNode node) {
+    node.visitChildren(_childVisitor);
+    return null;
+  }
+}
+
+/**
+ * A break statement.
+ *
+ * > breakStatement ::=
+ * >     'break' [SimpleIdentifier]? ';'
+ */
+class BreakStatement extends Statement {
+  /**
+   * The token representing the 'break' keyword.
+   */
+  Token breakKeyword;
+
+  /**
+   * The label associated with the statement, or `null` if there is no label.
+   */
+  SimpleIdentifier _label;
+
+  /**
+   * The semicolon terminating the statement.
+   */
+  Token semicolon;
+
+  /**
+   * The AstNode which this break statement is breaking from.  This will be
+   * either a [Statement] (in the case of breaking out of a loop), a
+   * [SwitchMember] (in the case of a labeled break statement whose label
+   * matches a label on a switch case in an enclosing switch statement), or
+   * `null` if the AST has not yet been resolved or if the target could not be
+   * resolved. Note that if the source code has errors, the target might be
+   * invalid (e.g. trying to break to a switch case).
+   */
+  AstNode target;
+
+  /**
+   * Initialize a newly created break statement. The [label] can be `null` if
+   * there is no label associated with the statement.
+   */
+  BreakStatement(this.breakKeyword, SimpleIdentifier label, this.semicolon) {
+    _label = _becomeParentOf(label);
+  }
+
+  @override
+  Token get beginToken => breakKeyword;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(breakKeyword)..add(_label)..add(semicolon);
+
+  @override
+  Token get endToken => semicolon;
+
+  /**
+   * Return the token representing the 'break' keyword.
+   */
+  @deprecated // Use "this.breakKeyword"
+  Token get keyword => breakKeyword;
+
+  /**
+   * Sethe token representing the 'break' keyword to the given [token].
+   */
+  @deprecated // Use "this.breakKeyword"
+  void set keyword(Token token) {
+    breakKeyword = token;
+  }
+
+  /**
+   * Return the label associated with the statement, or `null` if there is no
+   * label.
+   */
+  SimpleIdentifier get label => _label;
+
+  /**
+   * Set the label associated with the statement to the given [identifier].
+   */
+  void set label(SimpleIdentifier identifier) {
+    _label = _becomeParentOf(identifier);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitBreakStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_label, visitor);
+  }
+}
+
+/**
+ * A sequence of cascaded expressions: expressions that share a common target.
+ * There are three kinds of expressions that can be used in a cascade
+ * expression: [IndexExpression], [MethodInvocation] and [PropertyAccess].
+ *
+ * > cascadeExpression ::=
+ * >     [Expression] cascadeSection*
+ * >
+ * > cascadeSection ::=
+ * >     '..'  (cascadeSelector arguments*) (assignableSelector arguments*)*
+ * >     (assignmentOperator expressionWithoutCascade)?
+ * >
+ * > cascadeSelector ::=
+ * >     '[ ' expression '] '
+ * >   | identifier
+ */
+class CascadeExpression extends Expression {
+  /**
+   * The target of the cascade sections.
+   */
+  Expression _target;
+
+  /**
+   * The cascade sections sharing the common target.
+   */
+  NodeList<Expression> _cascadeSections;
+
+  /**
+   * Initialize a newly created cascade expression. The list of
+   * [cascadeSections] must contain at least one element.
+   */
+  CascadeExpression(Expression target, List<Expression> cascadeSections) {
+    _target = _becomeParentOf(target);
+    _cascadeSections = new NodeList<Expression>(this, cascadeSections);
+  }
+
+  @override
+  Token get beginToken => _target.beginToken;
+
+  /**
+   * Return the cascade sections sharing the common target.
+   */
+  NodeList<Expression> get cascadeSections => _cascadeSections;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(_target)
+    ..addAll(_cascadeSections);
+
+  @override
+  Token get endToken => _cascadeSections.endToken;
+
+  @override
+  int get precedence => 2;
+
+  /**
+   * Return the target of the cascade sections.
+   */
+  Expression get target => _target;
+
+  /**
+   * Set the target of the cascade sections to the given [expression].
+   */
+  void set target(Expression target) {
+    _target = _becomeParentOf(target);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitCascadeExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_target, visitor);
+    _cascadeSections.accept(visitor);
+  }
+}
+
+/**
+ * A catch clause within a try statement.
+ *
+ * > onPart ::=
+ * >     catchPart [Block]
+ * >   | 'on' type catchPart? [Block]
+ * >
+ * > catchPart ::=
+ * >     'catch' '(' [SimpleIdentifier] (',' [SimpleIdentifier])? ')'
+ */
+class CatchClause extends AstNode {
+  /**
+   * The token representing the 'on' keyword, or `null` if there is no 'on'
+   * keyword.
+   */
+  Token onKeyword;
+
+  /**
+   * The type of exceptions caught by this catch clause, or `null` if this catch
+   * clause catches every type of exception.
+   */
+  TypeName _exceptionType;
+
+  /**
+   * The token representing the 'catch' keyword, or `null` if there is no
+   * 'catch' keyword.
+   */
+  Token catchKeyword;
+
+  /**
+   * The left parenthesis, or `null` if there is no 'catch' keyword.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The parameter whose value will be the exception that was thrown, or `null`
+   * if there is no 'catch' keyword.
+   */
+  SimpleIdentifier _exceptionParameter;
+
+  /**
+   * The comma separating the exception parameter from the stack trace
+   * parameter, or `null` if there is no stack trace parameter.
+   */
+  Token comma;
+
+  /**
+   * The parameter whose value will be the stack trace associated with the
+   * exception, or `null` if there is no stack trace parameter.
+   */
+  SimpleIdentifier _stackTraceParameter;
+
+  /**
+   * The right parenthesis, or `null` if there is no 'catch' keyword.
+   */
+  Token rightParenthesis;
+
+  /**
+   * The body of the catch block.
+   */
+  Block _body;
+
+  /**
+   * Initialize a newly created catch clause. The [onKeyword] and
+   * [exceptionType] can be `null` if the clause will catch all exceptions. The
+   * [comma] and [stackTraceParameter] can be `null` if the stack trace is not
+   * referencable within the body.
+   */
+  CatchClause(this.onKeyword, TypeName exceptionType, this.catchKeyword,
+      this.leftParenthesis, SimpleIdentifier exceptionParameter, this.comma,
+      SimpleIdentifier stackTraceParameter, this.rightParenthesis, Block body) {
+    _exceptionType = _becomeParentOf(exceptionType);
+    _exceptionParameter = _becomeParentOf(exceptionParameter);
+    _stackTraceParameter = _becomeParentOf(stackTraceParameter);
+    _body = _becomeParentOf(body);
+  }
+
+  @override
+  Token get beginToken {
+    if (onKeyword != null) {
+      return onKeyword;
+    }
+    return catchKeyword;
+  }
+
+  /**
+   * Return the body of the catch block.
+   */
+  Block get body => _body;
+
+  /**
+   * Set the body of the catch block to the given [block].
+   */
+  void set body(Block block) {
+    _body = _becomeParentOf(block);
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(onKeyword)
+    ..add(_exceptionType)
+    ..add(catchKeyword)
+    ..add(leftParenthesis)
+    ..add(_exceptionParameter)
+    ..add(comma)
+    ..add(_stackTraceParameter)
+    ..add(rightParenthesis)
+    ..add(_body);
+
+  @override
+  Token get endToken => _body.endToken;
+
+  /**
+   * Return the parameter whose value will be the exception that was thrown, or
+   * `null` if there is no 'catch' keyword.
+   */
+  SimpleIdentifier get exceptionParameter => _exceptionParameter;
+
+  /**
+   * Set the parameter whose value will be the exception that was thrown to the
+   * given [parameter].
+   */
+  void set exceptionParameter(SimpleIdentifier parameter) {
+    _exceptionParameter = _becomeParentOf(parameter);
+  }
+
+  /**
+   * Return the type of exceptions caught by this catch clause, or `null` if
+   * this catch clause catches every type of exception.
+   */
+  TypeName get exceptionType => _exceptionType;
+
+  /**
+   * Set the type of exceptions caught by this catch clause to the given
+   * [exceptionType].
+   */
+  void set exceptionType(TypeName exceptionType) {
+    _exceptionType = _becomeParentOf(exceptionType);
+  }
+
+  /**
+   * Return the parameter whose value will be the stack trace associated with
+   * the exception, or `null` if there is no stack trace parameter.
+   */
+  SimpleIdentifier get stackTraceParameter => _stackTraceParameter;
+
+  /**
+   * Set the parameter whose value will be the stack trace associated with the
+   * exception to the given [parameter].
+   */
+  void set stackTraceParameter(SimpleIdentifier parameter) {
+    _stackTraceParameter = _becomeParentOf(parameter);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitCatchClause(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_exceptionType, visitor);
+    _safelyVisitChild(_exceptionParameter, visitor);
+    _safelyVisitChild(_stackTraceParameter, visitor);
+    _safelyVisitChild(_body, visitor);
+  }
+}
+
+/**
+ * Helper class to allow iteration of child entities of an AST node.
+ */
+class ChildEntities extends Object with IterableMixin implements Iterable {
+  /**
+   * The list of child entities to be iterated over.
+   */
+  List _entities = [];
+
+  @override
+  Iterator get iterator => _entities.iterator;
+
+  /**
+   * Add an AST node or token as the next child entity, if it is not null.
+   */
+  void add(entity) {
+    if (entity != null) {
+      assert(entity is Token || entity is AstNode);
+      _entities.add(entity);
+    }
+  }
+
+  /**
+   * Add the given items as the next child entities, if [items] is not null.
+   */
+  void addAll(Iterable items) {
+    if (items != null) {
+      _entities.addAll(items);
+    }
+  }
+}
+
+/**
+ * The declaration of a class.
+ *
+ * > classDeclaration ::=
+ * >     'abstract'? 'class' [SimpleIdentifier] [TypeParameterList]?
+ * >     ([ExtendsClause] [WithClause]?)?
+ * >     [ImplementsClause]?
+ * >     '{' [ClassMember]* '}'
+ */
+class ClassDeclaration extends NamedCompilationUnitMember {
+  /**
+   * The 'abstract' keyword, or `null` if the keyword was absent.
+   */
+  Token abstractKeyword;
+
+  /**
+   * The token representing the 'class' keyword.
+   */
+  Token classKeyword;
+
+  /**
+   * The type parameters for the class, or `null` if the class does not have any
+   * type parameters.
+   */
+  TypeParameterList _typeParameters;
+
+  /**
+   * The extends clause for the class, or `null` if the class does not extend
+   * any other class.
+   */
+  ExtendsClause _extendsClause;
+
+  /**
+   * The with clause for the class, or `null` if the class does not have a with
+   * clause.
+   */
+  WithClause _withClause;
+
+  /**
+   * The implements clause for the class, or `null` if the class does not
+   * implement any interfaces.
+   */
+  ImplementsClause _implementsClause;
+
+  /**
+   * The native clause for the class, or `null` if the class does not have a
+   * native clause.
+   */
+  NativeClause _nativeClause;
+
+  /**
+   * The left curly bracket.
+   */
+  Token leftBracket;
+
+  /**
+   * The members defined by the class.
+   */
+  NodeList<ClassMember> _members;
+
+  /**
+   * The right curly bracket.
+   */
+  Token rightBracket;
+
+  /**
+   * Initialize a newly created class declaration. Either or both of the
+   * [comment] and [metadata] can be `null` if the class does not have the
+   * corresponding attribute. The [abstractKeyword] can be `null` if the class
+   * is not abstract. The [typeParameters] can be `null` if the class does not
+   * have any type parameters. Any or all of the [extendsClause], [withClause],
+   * and [implementsClause] can be `null` if the class does not have the
+   * corresponding clause. The list of [members] can be `null` if the class does
+   * not have any members.
+   */
+  ClassDeclaration(Comment comment, List<Annotation> metadata,
+      this.abstractKeyword, this.classKeyword, SimpleIdentifier name,
+      TypeParameterList typeParameters, ExtendsClause extendsClause,
+      WithClause withClause, ImplementsClause implementsClause,
+      this.leftBracket, List<ClassMember> members, this.rightBracket)
+      : super(comment, metadata, name) {
+    _typeParameters = _becomeParentOf(typeParameters);
+    _extendsClause = _becomeParentOf(extendsClause);
+    _withClause = _becomeParentOf(withClause);
+    _implementsClause = _becomeParentOf(implementsClause);
+    _members = new NodeList<ClassMember>(this, members);
+  }
+
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(abstractKeyword)
+    ..add(classKeyword)
+    ..add(_name)
+    ..add(_typeParameters)
+    ..add(_extendsClause)
+    ..add(_withClause)
+    ..add(_implementsClause)
+    ..add(_nativeClause)
+    ..add(leftBracket)
+    ..addAll(members)
+    ..add(rightBracket);
+
+  @override
+  ClassElement get element =>
+      _name != null ? (_name.staticElement as ClassElement) : null;
+
+  @override
+  Token get endToken => rightBracket;
+
+  /**
+   * Return the extends clause for this class, or `null` if the class does not
+   * extend any other class.
+   */
+  ExtendsClause get extendsClause => _extendsClause;
+
+  /**
+   * Set the extends clause for this class to the given [extendsClause].
+   */
+  void set extendsClause(ExtendsClause extendsClause) {
+    _extendsClause = _becomeParentOf(extendsClause);
+  }
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata {
+    if (abstractKeyword != null) {
+      return abstractKeyword;
+    }
+    return classKeyword;
+  }
+
+  /**
+   * Return the implements clause for the class, or `null` if the class does not
+   * implement any interfaces.
+   */
+  ImplementsClause get implementsClause => _implementsClause;
+
+  /**
+   * Set the implements clause for the class to the given [implementsClause].
+   */
+  void set implementsClause(ImplementsClause implementsClause) {
+    _implementsClause = _becomeParentOf(implementsClause);
+  }
+
+  /**
+   * Return `true` if this class is declared to be an abstract class.
+   */
+  bool get isAbstract => abstractKeyword != null;
+
+  /**
+   * Return the members defined by the class.
+   */
+  NodeList<ClassMember> get members => _members;
+
+  /**
+   * Return the native clause for this class, or `null` if the class does not
+   * have a native clause.
+   */
+  NativeClause get nativeClause => _nativeClause;
+
+  /**
+   * Set the native clause for this class to the given [nativeClause].
+   */
+  void set nativeClause(NativeClause nativeClause) {
+    _nativeClause = _becomeParentOf(nativeClause);
+  }
+
+  /**
+   * Return the type parameters for the class, or `null` if the class does not
+   * have any type parameters.
+   */
+  TypeParameterList get typeParameters => _typeParameters;
+
+  /**
+   * Set the type parameters for the class to the given list of [typeParameters].
+   */
+  void set typeParameters(TypeParameterList typeParameters) {
+    _typeParameters = _becomeParentOf(typeParameters);
+  }
+
+  /**
+   * Return the with clause for the class, or `null` if the class does not have
+   * a with clause.
+   */
+  WithClause get withClause => _withClause;
+
+  /**
+   * Set the with clause for the class to the given [withClause].
+   */
+  void set withClause(WithClause withClause) {
+    _withClause = _becomeParentOf(withClause);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitClassDeclaration(this);
+
+  /**
+   * Return the constructor declared in the class with the given [name], or
+   * `null` if there is no such constructor. If the [name] is `null` then the
+   * default constructor will be searched for.
+   */
+  ConstructorDeclaration getConstructor(String name) {
+    for (ClassMember classMember in _members) {
+      if (classMember is ConstructorDeclaration) {
+        ConstructorDeclaration constructor = classMember;
+        SimpleIdentifier constructorName = constructor.name;
+        if (name == null && constructorName == null) {
+          return constructor;
+        }
+        if (constructorName != null && constructorName.name == name) {
+          return constructor;
+        }
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Return the field declared in the class with the given [name], or `null` if
+   * there is no such field.
+   */
+  VariableDeclaration getField(String name) {
+    for (ClassMember classMember in _members) {
+      if (classMember is FieldDeclaration) {
+        FieldDeclaration fieldDeclaration = classMember;
+        NodeList<VariableDeclaration> fields =
+            fieldDeclaration.fields.variables;
+        for (VariableDeclaration field in fields) {
+          SimpleIdentifier fieldName = field.name;
+          if (fieldName != null && name == fieldName.name) {
+            return field;
+          }
+        }
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Return the method declared in the class with the given [name], or `null` if
+   * there is no such method.
+   */
+  MethodDeclaration getMethod(String name) {
+    for (ClassMember classMember in _members) {
+      if (classMember is MethodDeclaration) {
+        MethodDeclaration method = classMember;
+        SimpleIdentifier methodName = method.name;
+        if (methodName != null && name == methodName.name) {
+          return method;
+        }
+      }
+    }
+    return null;
+  }
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_typeParameters, visitor);
+    _safelyVisitChild(_extendsClause, visitor);
+    _safelyVisitChild(_withClause, visitor);
+    _safelyVisitChild(_implementsClause, visitor);
+    _safelyVisitChild(_nativeClause, visitor);
+    members.accept(visitor);
+  }
+}
+
+/**
+ * A node that declares a name within the scope of a class.
+ */
+abstract class ClassMember extends Declaration {
+  /**
+   * Initialize a newly created member of a class. Either or both of the
+   * [comment] and [metadata] can be `null` if the member does not have the
+   * corresponding attribute.
+   */
+  ClassMember(Comment comment, List<Annotation> metadata)
+      : super(comment, metadata);
+}
+
+/**
+ * A class type alias.
+ *
+ * > classTypeAlias ::=
+ * >     [SimpleIdentifier] [TypeParameterList]? '=' 'abstract'? mixinApplication
+ * >
+ * > mixinApplication ::=
+ * >     [TypeName] [WithClause] [ImplementsClause]? ';'
+ */
+class ClassTypeAlias extends TypeAlias {
+  /**
+   * The type parameters for the class, or `null` if the class does not have any
+   * type parameters.
+   */
+  TypeParameterList _typeParameters;
+
+  /**
+   * The token for the '=' separating the name from the definition.
+   */
+  Token equals;
+
+  /**
+   * The token for the 'abstract' keyword, or `null` if this is not defining an
+   * abstract class.
+   */
+  Token abstractKeyword;
+
+  /**
+   * The name of the superclass of the class being declared.
+   */
+  TypeName _superclass;
+
+  /**
+   * The with clause for this class.
+   */
+  WithClause _withClause;
+
+  /**
+   * The implements clause for this class, or `null` if there is no implements
+   * clause.
+   */
+  ImplementsClause _implementsClause;
+
+  /**
+   * Initialize a newly created class type alias. Either or both of the
+   * [comment] and [metadata] can be `null` if the class type alias does not
+   * have the corresponding attribute. The [typeParameters] can be `null` if the
+   * class does not have any type parameters. The [abstractKeyword] can be
+   * `null` if the class is not abstract. The [implementsClause] can be `null`
+   * if the class does not implement any interfaces.
+   */
+  ClassTypeAlias(Comment comment, List<Annotation> metadata, Token keyword,
+      SimpleIdentifier name, TypeParameterList typeParameters, this.equals,
+      this.abstractKeyword, TypeName superclass, WithClause withClause,
+      ImplementsClause implementsClause, Token semicolon)
+      : super(comment, metadata, keyword, name, semicolon) {
+    _typeParameters = _becomeParentOf(typeParameters);
+    _superclass = _becomeParentOf(superclass);
+    _withClause = _becomeParentOf(withClause);
+    _implementsClause = _becomeParentOf(implementsClause);
+  }
+
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(typedefKeyword)
+    ..add(_name)
+    ..add(_typeParameters)
+    ..add(equals)
+    ..add(abstractKeyword)
+    ..add(_superclass)
+    ..add(_withClause)
+    ..add(_implementsClause)
+    ..add(semicolon);
+
+  @override
+  ClassElement get element =>
+      _name != null ? (_name.staticElement as ClassElement) : null;
+
+  /**
+   * Return the implements clause for this class, or `null` if there is no
+   * implements clause.
+   */
+  ImplementsClause get implementsClause => _implementsClause;
+
+  /**
+   * Set the implements clause for this class to the given [implementsClause].
+   */
+  void set implementsClause(ImplementsClause implementsClause) {
+    _implementsClause = _becomeParentOf(implementsClause);
+  }
+
+  /**
+   * Return `true` if this class is declared to be an abstract class.
+   */
+  bool get isAbstract => abstractKeyword != null;
+
+  /**
+   * Return the name of the superclass of the class being declared.
+   */
+  TypeName get superclass => _superclass;
+
+  /**
+   * Set the name of the superclass of the class being declared to the given
+   * [superclass] name.
+   */
+  void set superclass(TypeName superclass) {
+    _superclass = _becomeParentOf(superclass);
+  }
+
+  /**
+   * Return the type parameters for the class, or `null` if the class does not
+   * have any type parameters.
+   */
+  TypeParameterList get typeParameters => _typeParameters;
+
+  /**
+   * Set the type parameters for the class to the given list of [typeParameters].
+   */
+  void set typeParameters(TypeParameterList typeParameters) {
+    _typeParameters = _becomeParentOf(typeParameters);
+  }
+
+  /**
+   * Return the with clause for this class.
+   */
+  WithClause get withClause => _withClause;
+
+  /**
+   * Set the with clause for this class to the given with [withClause].
+   */
+  void set withClause(WithClause withClause) {
+    _withClause = _becomeParentOf(withClause);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitClassTypeAlias(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_typeParameters, visitor);
+    _safelyVisitChild(_superclass, visitor);
+    _safelyVisitChild(_withClause, visitor);
+    _safelyVisitChild(_implementsClause, visitor);
+  }
+}
+
+/**
+ * A combinator associated with an import or export directive.
+ *
+ * > combinator ::=
+ * >     [HideCombinator]
+ * >   | [ShowCombinator]
+ */
+abstract class Combinator extends AstNode {
+  /**
+   * The 'hide' or 'show' keyword specifying what kind of processing is to be
+   * done on the names.
+   */
+  Token keyword;
+
+  /**
+   * Initialize a newly created combinator.
+   */
+  Combinator(this.keyword);
+
+  @override
+  Token get beginToken => keyword;
+}
+
+/**
+ * A comment within the source code.
+ *
+ * > comment ::=
+ * >     endOfLineComment
+ * >   | blockComment
+ * >   | documentationComment
+ * >
+ * > endOfLineComment ::=
+ * >     '//' (CHARACTER - EOL)* EOL
+ * >
+ * > blockComment ::=
+ * >     '/ *' CHARACTER* '&#42;/'
+ * >
+ * > documentationComment ::=
+ * >     '/ **' (CHARACTER | [CommentReference])* '&#42;/'
+ * >   | ('///' (CHARACTER - EOL)* EOL)+
+ */
+class Comment extends AstNode {
+  /**
+   * The tokens representing the comment.
+   */
+  final List<Token> tokens;
+
+  /**
+   * The type of the comment.
+   */
+  final CommentType _type;
+
+  /**
+   * The references embedded within the documentation comment. This list will be
+   * empty unless this is a documentation comment that has references embedded
+   * within it.
+   */
+  NodeList<CommentReference> _references;
+
+  /**
+   * Initialize a newly created comment. The list of [tokens] must contain at
+   * least one token. The [type] is the type of the comment. The list of
+   * [references] can be empty if the comment does not contain any embedded
+   * references.
+   */
+  Comment(this.tokens, this._type, List<CommentReference> references) {
+    _references = new NodeList<CommentReference>(this, references);
+  }
+
+  @override
+  Token get beginToken => tokens[0];
+
+  @override
+  Iterable get childEntities => new ChildEntities()..addAll(tokens);
+
+  @override
+  Token get endToken => tokens[tokens.length - 1];
+
+  /**
+   * Return `true` if this is a block comment.
+   */
+  bool get isBlock => _type == CommentType.BLOCK;
+
+  /**
+   * Return `true` if this is a documentation comment.
+   */
+  bool get isDocumentation => _type == CommentType.DOCUMENTATION;
+
+  /**
+   * Return `true` if this is an end-of-line comment.
+   */
+  bool get isEndOfLine => _type == CommentType.END_OF_LINE;
+
+  /**
+   * Return the references embedded within the documentation comment.
+   */
+  NodeList<CommentReference> get references => _references;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitComment(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _references.accept(visitor);
+  }
+
+  /**
+   * Create a block comment consisting of the given [tokens].
+   */
+  static Comment createBlockComment(List<Token> tokens) =>
+      new Comment(tokens, CommentType.BLOCK, null);
+
+  /**
+   * Create a documentation comment consisting of the given [tokens].
+   */
+  static Comment createDocumentationComment(List<Token> tokens) => new Comment(
+      tokens, CommentType.DOCUMENTATION, new List<CommentReference>());
+
+  /**
+   * Create a documentation comment consisting of the given [tokens] and having
+   * the given [references] embedded within it.
+   */
+  static Comment createDocumentationCommentWithReferences(
+          List<Token> tokens, List<CommentReference> references) =>
+      new Comment(tokens, CommentType.DOCUMENTATION, references);
+
+  /**
+   * Create an end-of-line comment consisting of the given [tokens].
+   */
+  static Comment createEndOfLineComment(List<Token> tokens) =>
+      new Comment(tokens, CommentType.END_OF_LINE, null);
+}
+
+/**
+ * A reference to a Dart element that is found within a documentation comment.
+ *
+ * > commentReference ::=
+ * >     '[' 'new'? [Identifier] ']'
+ */
+class CommentReference extends AstNode {
+  /**
+   * The token representing the 'new' keyword, or `null` if there was no 'new'
+   * keyword.
+   */
+  Token newKeyword;
+
+  /**
+   * The identifier being referenced.
+   */
+  Identifier _identifier;
+
+  /**
+   * Initialize a newly created reference to a Dart element. The [newKeyword]
+   * can be `null` if the reference is not to a constructor.
+   */
+  CommentReference(this.newKeyword, Identifier identifier) {
+    _identifier = _becomeParentOf(identifier);
+  }
+
+  @override
+  Token get beginToken => _identifier.beginToken;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(newKeyword)..add(_identifier);
+
+  @override
+  Token get endToken => _identifier.endToken;
+
+  /**
+   * Return the identifier being referenced.
+   */
+  Identifier get identifier => _identifier;
+
+  /**
+   * Set the identifier being referenced to the given [identifier].
+   */
+  void set identifier(Identifier identifier) {
+    _identifier = _becomeParentOf(identifier);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitCommentReference(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_identifier, visitor);
+  }
+}
+
+/**
+ * The possible types of comments that are recognized by the parser.
+ */
+class CommentType {
+  /**
+   * A block comment.
+   */
+  static const CommentType BLOCK = const CommentType('BLOCK');
+
+  /**
+   * A documentation comment.
+   */
+  static const CommentType DOCUMENTATION = const CommentType('DOCUMENTATION');
+
+  /**
+   * An end-of-line comment.
+   */
+  static const CommentType END_OF_LINE = const CommentType('END_OF_LINE');
+
+  /**
+   * The name of the comment type.
+   */
+  final String name;
+
+  /**
+   * Initialize a newly created comment type to have the given [name].
+   */
+  const CommentType(this.name);
+
+  @override
+  String toString() => name;
+}
+
+/**
+ * A compilation unit.
+ *
+ * While the grammar restricts the order of the directives and declarations
+ * within a compilation unit, this class does not enforce those restrictions.
+ * In particular, the children of a compilation unit will be visited in lexical
+ * order even if lexical order does not conform to the restrictions of the
+ * grammar.
+ *
+ * > compilationUnit ::=
+ * >     directives declarations
+ * >
+ * > directives ::=
+ * >     [ScriptTag]? [LibraryDirective]? namespaceDirective* [PartDirective]*
+ * >   | [PartOfDirective]
+ * >
+ * > namespaceDirective ::=
+ * >     [ImportDirective]
+ * >   | [ExportDirective]
+ * >
+ * > declarations ::=
+ * >     [CompilationUnitMember]*
+ */
+class CompilationUnit extends AstNode {
+  /**
+   * The first token in the token stream that was parsed to form this
+   * compilation unit.
+   */
+  Token beginToken;
+
+  /**
+   * The script tag at the beginning of the compilation unit, or `null` if there
+   * is no script tag in this compilation unit.
+   */
+  ScriptTag _scriptTag;
+
+  /**
+   * The directives contained in this compilation unit.
+   */
+  NodeList<Directive> _directives;
+
+  /**
+   * The declarations contained in this compilation unit.
+   */
+  NodeList<CompilationUnitMember> _declarations;
+
+  /**
+   * The last token in the token stream that was parsed to form this compilation
+   * unit. This token should always have a type of [TokenType.EOF].
+   */
+  Token endToken;
+
+  /**
+   * The element associated with this compilation unit, or `null` if the AST
+   * structure has not been resolved.
+   */
+  CompilationUnitElement element;
+
+  /**
+   * The line information for this compilation unit.
+   */
+  LineInfo lineInfo;
+
+  /**
+   * Initialize a newly created compilation unit to have the given directives
+   * and declarations. The [scriptTag] can be `null` if there is no script tag
+   * in the compilation unit. The list of [directives] can be `null` if there
+   * are no directives in the compilation unit. The list of [declarations] can
+   * be `null` if there are no declarations in the compilation unit.
+   */
+  CompilationUnit(this.beginToken, ScriptTag scriptTag,
+      List<Directive> directives, List<CompilationUnitMember> declarations,
+      this.endToken) {
+    _scriptTag = _becomeParentOf(scriptTag);
+    _directives = new NodeList<Directive>(this, directives);
+    _declarations = new NodeList<CompilationUnitMember>(this, declarations);
+  }
+
+  @override
+  Iterable get childEntities {
+    ChildEntities result = new ChildEntities()..add(_scriptTag);
+    if (_directivesAreBeforeDeclarations) {
+      result..addAll(_directives)..addAll(_declarations);
+    } else {
+      result.addAll(sortedDirectivesAndDeclarations);
+    }
+    return result;
+  }
+
+  /**
+   * Return the declarations contained in this compilation unit.
+   */
+  NodeList<CompilationUnitMember> get declarations => _declarations;
+
+  /**
+   * Return the directives contained in this compilation unit.
+   */
+  NodeList<Directive> get directives => _directives;
+
+  @override
+  int get length {
+    Token endToken = this.endToken;
+    if (endToken == null) {
+      return 0;
+    }
+    return endToken.offset + endToken.length;
+  }
+
+  @override
+  int get offset => 0;
+
+  /**
+   * Return the script tag at the beginning of the compilation unit, or `null`
+   * if there is no script tag in this compilation unit.
+   */
+  ScriptTag get scriptTag => _scriptTag;
+
+  /**
+   * Set the script tag at the beginning of the compilation unit to the given
+   * [scriptTag].
+   */
+  void set scriptTag(ScriptTag scriptTag) {
+    _scriptTag = _becomeParentOf(scriptTag);
+  }
+
+  /**
+   * Return a list containing all of the directives and declarations in this
+   * compilation unit, sorted in lexical order.
+   */
+  List<AstNode> get sortedDirectivesAndDeclarations {
+    return <AstNode>[]
+      ..addAll(_directives)
+      ..addAll(_declarations)
+      ..sort(AstNode.LEXICAL_ORDER);
+  }
+
+  /**
+   * Return `true` if all of the directives are lexically before any
+   * declarations.
+   */
+  bool get _directivesAreBeforeDeclarations {
+    if (_directives.isEmpty || _declarations.isEmpty) {
+      return true;
+    }
+    Directive lastDirective = _directives[_directives.length - 1];
+    CompilationUnitMember firstDeclaration = _declarations[0];
+    return lastDirective.offset < firstDeclaration.offset;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitCompilationUnit(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_scriptTag, visitor);
+    if (_directivesAreBeforeDeclarations) {
+      _directives.accept(visitor);
+      _declarations.accept(visitor);
+    } else {
+      for (AstNode child in sortedDirectivesAndDeclarations) {
+        child.accept(visitor);
+      }
+    }
+  }
+}
+
+/**
+ * A node that declares one or more names within the scope of a compilation
+ * unit.
+ *
+ * > compilationUnitMember ::=
+ * >     [ClassDeclaration]
+ * >   | [TypeAlias]
+ * >   | [FunctionDeclaration]
+ * >   | [MethodDeclaration]
+ * >   | [VariableDeclaration]
+ * >   | [VariableDeclaration]
+ */
+abstract class CompilationUnitMember extends Declaration {
+  /**
+   * Initialize a newly created generic compilation unit member. Either or both
+   * of the [comment] and [metadata] can be `null` if the member does not have
+   * the corresponding attribute.
+   */
+  CompilationUnitMember(Comment comment, List<Annotation> metadata)
+      : super(comment, metadata);
+}
+
+/**
+ * A conditional expression.
+ *
+ * > conditionalExpression ::=
+ * >     [Expression] '?' [Expression] ':' [Expression]
+ */
+class ConditionalExpression extends Expression {
+  /**
+   * The condition used to determine which of the expressions is executed next.
+   */
+  Expression _condition;
+
+  /**
+   * The token used to separate the condition from the then expression.
+   */
+  Token question;
+
+  /**
+   * The expression that is executed if the condition evaluates to `true`.
+   */
+  Expression _thenExpression;
+
+  /**
+   * The token used to separate the then expression from the else expression.
+   */
+  Token colon;
+
+  /**
+   * The expression that is executed if the condition evaluates to `false`.
+   */
+  Expression _elseExpression;
+
+  /**
+   * Initialize a newly created conditional expression.
+   */
+  ConditionalExpression(Expression condition, this.question,
+      Expression thenExpression, this.colon, Expression elseExpression) {
+    _condition = _becomeParentOf(condition);
+    _thenExpression = _becomeParentOf(thenExpression);
+    _elseExpression = _becomeParentOf(elseExpression);
+  }
+
+  @override
+  Token get beginToken => _condition.beginToken;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(_condition)
+    ..add(question)
+    ..add(_thenExpression)
+    ..add(colon)
+    ..add(_elseExpression);
+
+  /**
+   * Return the condition used to determine which of the expressions is executed
+   * next.
+   */
+  Expression get condition => _condition;
+
+  /**
+   * Set the condition used to determine which of the expressions is executed
+   * next to the given [expression].
+   */
+  void set condition(Expression expression) {
+    _condition = _becomeParentOf(expression);
+  }
+
+  /**
+   * Return the expression that is executed if the condition evaluates to
+   * `false`.
+   */
+  Expression get elseExpression => _elseExpression;
+
+  /**
+   * Set the expression that is executed if the condition evaluates to `false`
+   * to the given [expression].
+   */
+  void set elseExpression(Expression expression) {
+    _elseExpression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get endToken => _elseExpression.endToken;
+
+  @override
+  int get precedence => 3;
+
+  /**
+   * Return the expression that is executed if the condition evaluates to
+   * `true`.
+   */
+  Expression get thenExpression => _thenExpression;
+
+  /**
+   * Set the expression that is executed if the condition evaluates to `true` to
+   * the given [expression].
+   */
+  void set thenExpression(Expression expression) {
+    _thenExpression = _becomeParentOf(expression);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitConditionalExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_condition, visitor);
+    _safelyVisitChild(_thenExpression, visitor);
+    _safelyVisitChild(_elseExpression, visitor);
+  }
+}
+
+/**
+ * An object that can be used to evaluate constant expressions to produce their
+ * compile-time value. According to the Dart Language Specification:
+ * <blockquote>
+ * A constant expression is one of the following:
+ * * A literal number.
+ * * A literal boolean.
+ * * A literal string where any interpolated expression is a compile-time
+ *   constant that evaluates to a numeric, string or boolean value or to `null`.
+ * * `null`.
+ * * A reference to a static constant variable.
+ * * An identifier expression that denotes a constant variable, a class or a
+ *   type parameter.
+ * * A constant constructor invocation.
+ * * A constant list literal.
+ * * A constant map literal.
+ * * A simple or qualified identifier denoting a top-level function or a static
+ *   method.
+ * * A parenthesized expression `(e)` where `e` is a constant expression.
+ * * An expression of one of the forms `identical(e1, e2)`, `e1 == e2`,
+ *   `e1 != e2` where `e1` and `e2` are constant expressions that evaluate to a
+ *   numeric, string or boolean value or to `null`.
+ * * An expression of one of the forms `!e`, `e1 && e2` or `e1 || e2`, where
+ *   `e`, `e1` and `e2` are constant expressions that evaluate to a boolean
+ *   value or to `null`.
+ * * An expression of one of the forms `~e`, `e1 ^ e2`, `e1 & e2`, `e1 | e2`,
+ *   `e1 >> e2` or `e1 << e2`, where `e`, `e1` and `e2` are constant expressions
+ *   that evaluate to an integer value or to `null`.
+ * * An expression of one of the forms `-e`, `e1 + e2`, `e1 - e2`, `e1 * e2`,
+ *   `e1 / e2`, `e1 ~/ e2`, `e1 > e2`, `e1 < e2`, `e1 >= e2`, `e1 <= e2` or
+ *   `e1 % e2`, where `e`, `e1` and `e2` are constant expressions that evaluate
+ *   to a numeric value or to `null`.
+ * </blockquote>
+ * The values returned by instances of this class are therefore `null` and
+ * instances of the classes `Boolean`, `BigInteger`, `Double`, `String`, and
+ * `DartObject`.
+ *
+ * In addition, this class defines several values that can be returned to
+ * indicate various conditions encountered during evaluation. These are
+ * documented with the static fields that define those values.
+ */
+class ConstantEvaluator extends GeneralizingAstVisitor<Object> {
+  /**
+   * The value returned for expressions (or non-expression nodes) that are not
+   * compile-time constant expressions.
+   */
+  static Object NOT_A_CONSTANT = new Object();
+
+  @override
+  Object visitAdjacentStrings(AdjacentStrings node) {
+    StringBuffer buffer = new StringBuffer();
+    for (StringLiteral string in node.strings) {
+      Object value = string.accept(this);
+      if (identical(value, NOT_A_CONSTANT)) {
+        return value;
+      }
+      buffer.write(value);
+    }
+    return buffer.toString();
+  }
+
+  @override
+  Object visitBinaryExpression(BinaryExpression node) {
+    Object leftOperand = node.leftOperand.accept(this);
+    if (identical(leftOperand, NOT_A_CONSTANT)) {
+      return leftOperand;
+    }
+    Object rightOperand = node.rightOperand.accept(this);
+    if (identical(rightOperand, NOT_A_CONSTANT)) {
+      return rightOperand;
+    }
+    while (true) {
+      if (node.operator.type == TokenType.AMPERSAND) {
+        // integer or {@code null}
+        if (leftOperand is int && rightOperand is int) {
+          return leftOperand & rightOperand;
+        }
+      } else if (node.operator.type == TokenType.AMPERSAND_AMPERSAND) {
+        // boolean or {@code null}
+        if (leftOperand is bool && rightOperand is bool) {
+          return leftOperand && rightOperand;
+        }
+      } else if (node.operator.type == TokenType.BANG_EQ) {
+        // numeric, string, boolean, or {@code null}
+        if (leftOperand is bool && rightOperand is bool) {
+          return leftOperand != rightOperand;
+        } else if (leftOperand is num && rightOperand is num) {
+          return leftOperand != rightOperand;
+        } else if (leftOperand is String && rightOperand is String) {
+          return leftOperand != rightOperand;
+        }
+      } else if (node.operator.type == TokenType.BAR) {
+        // integer or {@code null}
+        if (leftOperand is int && rightOperand is int) {
+          return leftOperand | rightOperand;
+        }
+      } else if (node.operator.type == TokenType.BAR_BAR) {
+        // boolean or {@code null}
+        if (leftOperand is bool && rightOperand is bool) {
+          return leftOperand || rightOperand;
+        }
+      } else if (node.operator.type == TokenType.CARET) {
+        // integer or {@code null}
+        if (leftOperand is int && rightOperand is int) {
+          return leftOperand ^ rightOperand;
+        }
+      } else if (node.operator.type == TokenType.EQ_EQ) {
+        // numeric, string, boolean, or {@code null}
+        if (leftOperand is bool && rightOperand is bool) {
+          return leftOperand == rightOperand;
+        } else if (leftOperand is num && rightOperand is num) {
+          return leftOperand == rightOperand;
+        } else if (leftOperand is String && rightOperand is String) {
+          return leftOperand == rightOperand;
+        }
+      } else if (node.operator.type == TokenType.GT) {
+        // numeric or {@code null}
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand.compareTo(rightOperand) > 0;
+        }
+      } else if (node.operator.type == TokenType.GT_EQ) {
+        // numeric or {@code null}
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand.compareTo(rightOperand) >= 0;
+        }
+      } else if (node.operator.type == TokenType.GT_GT) {
+        // integer or {@code null}
+        if (leftOperand is int && rightOperand is int) {
+          return leftOperand >> rightOperand;
+        }
+      } else if (node.operator.type == TokenType.LT) {
+        // numeric or {@code null}
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand.compareTo(rightOperand) < 0;
+        }
+      } else if (node.operator.type == TokenType.LT_EQ) {
+        // numeric or {@code null}
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand.compareTo(rightOperand) <= 0;
+        }
+      } else if (node.operator.type == TokenType.LT_LT) {
+        // integer or {@code null}
+        if (leftOperand is int && rightOperand is int) {
+          return leftOperand << rightOperand;
+        }
+      } else if (node.operator.type == TokenType.MINUS) {
+        // numeric or {@code null}
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand - rightOperand;
+        }
+      } else if (node.operator.type == TokenType.PERCENT) {
+        // numeric or {@code null}
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand.remainder(rightOperand);
+        }
+      } else if (node.operator.type == TokenType.PLUS) {
+        // numeric or {@code null}
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand + rightOperand;
+        }
+      } else if (node.operator.type == TokenType.STAR) {
+        // numeric or {@code null}
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand * rightOperand;
+        }
+      } else if (node.operator.type == TokenType.SLASH) {
+        // numeric or {@code null}
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand / rightOperand;
+        }
+      } else if (node.operator.type == TokenType.TILDE_SLASH) {
+        // numeric or {@code null}
+        if (leftOperand is num && rightOperand is num) {
+          return leftOperand ~/ rightOperand;
+        }
+      } else {}
+      break;
+    }
+    // TODO(brianwilkerson) This doesn't handle numeric conversions.
+    return visitExpression(node);
+  }
+
+  @override
+  Object visitBooleanLiteral(BooleanLiteral node) => node.value ? true : false;
+
+  @override
+  Object visitDoubleLiteral(DoubleLiteral node) => node.value;
+
+  @override
+  Object visitIntegerLiteral(IntegerLiteral node) => node.value;
+
+  @override
+  Object visitInterpolationExpression(InterpolationExpression node) {
+    Object value = node.expression.accept(this);
+    if (value == null || value is bool || value is String || value is num) {
+      return value;
+    }
+    return NOT_A_CONSTANT;
+  }
+
+  @override
+  Object visitInterpolationString(InterpolationString node) => node.value;
+
+  @override
+  Object visitListLiteral(ListLiteral node) {
+    List<Object> list = new List<Object>();
+    for (Expression element in node.elements) {
+      Object value = element.accept(this);
+      if (identical(value, NOT_A_CONSTANT)) {
+        return value;
+      }
+      list.add(value);
+    }
+    return list;
+  }
+
+  @override
+  Object visitMapLiteral(MapLiteral node) {
+    HashMap<String, Object> map = new HashMap<String, Object>();
+    for (MapLiteralEntry entry in node.entries) {
+      Object key = entry.key.accept(this);
+      Object value = entry.value.accept(this);
+      if (key is! String || identical(value, NOT_A_CONSTANT)) {
+        return NOT_A_CONSTANT;
+      }
+      map[(key as String)] = value;
+    }
+    return map;
+  }
+
+  @override
+  Object visitMethodInvocation(MethodInvocation node) => visitNode(node);
+
+  @override
+  Object visitNode(AstNode node) => NOT_A_CONSTANT;
+
+  @override
+  Object visitNullLiteral(NullLiteral node) => null;
+
+  @override
+  Object visitParenthesizedExpression(ParenthesizedExpression node) =>
+      node.expression.accept(this);
+
+  @override
+  Object visitPrefixedIdentifier(PrefixedIdentifier node) =>
+      _getConstantValue(null);
+
+  @override
+  Object visitPrefixExpression(PrefixExpression node) {
+    Object operand = node.operand.accept(this);
+    if (identical(operand, NOT_A_CONSTANT)) {
+      return operand;
+    }
+    while (true) {
+      if (node.operator.type == TokenType.BANG) {
+        if (identical(operand, true)) {
+          return false;
+        } else if (identical(operand, false)) {
+          return true;
+        }
+      } else if (node.operator.type == TokenType.TILDE) {
+        if (operand is int) {
+          return ~operand;
+        }
+      } else if (node.operator.type == TokenType.MINUS) {
+        if (operand == null) {
+          return null;
+        } else if (operand is num) {
+          return -operand;
+        }
+      } else {}
+      break;
+    }
+    return NOT_A_CONSTANT;
+  }
+
+  @override
+  Object visitPropertyAccess(PropertyAccess node) => _getConstantValue(null);
+
+  @override
+  Object visitSimpleIdentifier(SimpleIdentifier node) =>
+      _getConstantValue(null);
+
+  @override
+  Object visitSimpleStringLiteral(SimpleStringLiteral node) => node.value;
+
+  @override
+  Object visitStringInterpolation(StringInterpolation node) {
+    StringBuffer buffer = new StringBuffer();
+    for (InterpolationElement element in node.elements) {
+      Object value = element.accept(this);
+      if (identical(value, NOT_A_CONSTANT)) {
+        return value;
+      }
+      buffer.write(value);
+    }
+    return buffer.toString();
+  }
+
+  @override
+  Object visitSymbolLiteral(SymbolLiteral node) {
+    // TODO(brianwilkerson) This isn't optimal because a Symbol is not a String.
+    StringBuffer buffer = new StringBuffer();
+    for (Token component in node.components) {
+      if (buffer.length > 0) {
+        buffer.writeCharCode(0x2E);
+      }
+      buffer.write(component.lexeme);
+    }
+    return buffer.toString();
+  }
+
+  /**
+   * Return the constant value of the static constant represented by the given
+   * [element].
+   */
+  Object _getConstantValue(Element element) {
+    // TODO(brianwilkerson) Implement this
+    if (element is FieldElement) {
+      FieldElement field = element;
+      if (field.isStatic && field.isConst) {
+        //field.getConstantValue();
+      }
+      //    } else if (element instanceof VariableElement) {
+      //      VariableElement variable = (VariableElement) element;
+      //      if (variable.isStatic() && variable.isConst()) {
+      //        //variable.getConstantValue();
+      //      }
+    }
+    return NOT_A_CONSTANT;
+  }
+}
+
+/**
+ * A constructor declaration.
+ *
+ * > constructorDeclaration ::=
+ * >     constructorSignature [FunctionBody]?
+ * >   | constructorName formalParameterList ':' 'this' ('.' [SimpleIdentifier])? arguments
+ * >
+ * > constructorSignature ::=
+ * >     'external'? constructorName formalParameterList initializerList?
+ * >   | 'external'? 'factory' factoryName formalParameterList initializerList?
+ * >   | 'external'? 'const'  constructorName formalParameterList initializerList?
+ * >
+ * > constructorName ::=
+ * >     [SimpleIdentifier] ('.' [SimpleIdentifier])?
+ * >
+ * > factoryName ::=
+ * >     [Identifier] ('.' [SimpleIdentifier])?
+ * >
+ * > initializerList ::=
+ * >     ':' [ConstructorInitializer] (',' [ConstructorInitializer])*
+ */
+class ConstructorDeclaration extends ClassMember {
+  /**
+   * The token for the 'external' keyword, or `null` if the constructor is not
+   * external.
+   */
+  Token externalKeyword;
+
+  /**
+   * The token for the 'const' keyword, or `null` if the constructor is not a
+   * const constructor.
+   */
+  Token constKeyword;
+
+  /**
+   * The token for the 'factory' keyword, or `null` if the constructor is not a
+   * factory constructor.
+   */
+  Token factoryKeyword;
+
+  /**
+   * The type of object being created. This can be different than the type in
+   * which the constructor is being declared if the constructor is the
+   * implementation of a factory constructor.
+   */
+  Identifier _returnType;
+
+  /**
+   * The token for the period before the constructor name, or `null` if the
+   * constructor being declared is unnamed.
+   */
+  Token period;
+
+  /**
+   * The name of the constructor, or `null` if the constructor being declared is
+   * unnamed.
+   */
+  SimpleIdentifier _name;
+
+  /**
+   * The parameters associated with the constructor.
+   */
+  FormalParameterList _parameters;
+
+  /**
+   * The token for the separator (colon or equals) before the initializer list
+   * or redirection, or `null` if there are no initializers.
+   */
+  Token separator;
+
+  /**
+   * The initializers associated with the constructor.
+   */
+  NodeList<ConstructorInitializer> _initializers;
+
+  /**
+   * The name of the constructor to which this constructor will be redirected,
+   * or `null` if this is not a redirecting factory constructor.
+   */
+  ConstructorName _redirectedConstructor;
+
+  /**
+   * The body of the constructor, or `null` if the constructor does not have a
+   * body.
+   */
+  FunctionBody _body;
+
+  /**
+   * The element associated with this constructor, or `null` if the AST
+   * structure has not been resolved or if this constructor could not be
+   * resolved.
+   */
+  ConstructorElement element;
+
+  /**
+   * Initialize a newly created constructor declaration. The [externalKeyword]
+   * can be `null` if the constructor is not external. Either or both of the
+   * [comment] and [metadata] can be `null` if the constructor does not have the
+   * corresponding attribute. The [constKeyword] can be `null` if the
+   * constructor cannot be used to create a constant. The [factoryKeyword] can
+   * be `null` if the constructor is not a factory. The [period] and [name] can
+   * both be `null` if the constructor is not a named constructor. The
+   * [separator] can be `null` if the constructor does not have any initializers
+   * and does not redirect to a different constructor. The list of
+   * [initializers] can be `null` if the constructor does not have any
+   * initializers. The [redirectedConstructor] can be `null` if the constructor
+   * does not redirect to a different constructor. The [body] can be `null` if
+   * the constructor does not have a body.
+   */
+  ConstructorDeclaration(Comment comment, List<Annotation> metadata,
+      this.externalKeyword, this.constKeyword, this.factoryKeyword,
+      Identifier returnType, this.period, SimpleIdentifier name,
+      FormalParameterList parameters, this.separator,
+      List<ConstructorInitializer> initializers,
+      ConstructorName redirectedConstructor, FunctionBody body)
+      : super(comment, metadata) {
+    _returnType = _becomeParentOf(returnType);
+    _name = _becomeParentOf(name);
+    _parameters = _becomeParentOf(parameters);
+    _initializers = new NodeList<ConstructorInitializer>(this, initializers);
+    _redirectedConstructor = _becomeParentOf(redirectedConstructor);
+    _body = _becomeParentOf(body);
+  }
+
+  /**
+   * Return the body of the constructor, or `null` if the constructor does not
+   * have a body.
+   */
+  FunctionBody get body => _body;
+
+  /**
+   * Set the body of the constructor to the given [functionBody].
+   */
+  void set body(FunctionBody functionBody) {
+    _body = _becomeParentOf(functionBody);
+  }
+
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(externalKeyword)
+    ..add(constKeyword)
+    ..add(factoryKeyword)
+    ..add(_returnType)
+    ..add(period)
+    ..add(_name)
+    ..add(_parameters)
+    ..add(separator)
+    ..addAll(initializers)
+    ..add(_redirectedConstructor)
+    ..add(_body);
+
+  @override
+  Token get endToken {
+    if (_body != null) {
+      return _body.endToken;
+    } else if (!_initializers.isEmpty) {
+      return _initializers.endToken;
+    }
+    return _parameters.endToken;
+  }
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata {
+    Token leftMost =
+        Token.lexicallyFirst([externalKeyword, constKeyword, factoryKeyword]);
+    if (leftMost != null) {
+      return leftMost;
+    }
+    return _returnType.beginToken;
+  }
+
+  /**
+   * Return the initializers associated with the constructor.
+   */
+  NodeList<ConstructorInitializer> get initializers => _initializers;
+
+  /**
+   * Return the name of the constructor, or `null` if the constructor being
+   * declared is unnamed.
+   */
+  SimpleIdentifier get name => _name;
+
+  /**
+   * Set the name of the constructor to the given [identifier].
+   */
+  void set name(SimpleIdentifier identifier) {
+    _name = _becomeParentOf(identifier);
+  }
+
+  /**
+   * Return the parameters associated with the constructor.
+   */
+  FormalParameterList get parameters => _parameters;
+
+  /**
+   * Set the parameters associated with the constructor to the given list of
+   * [parameters].
+   */
+  void set parameters(FormalParameterList parameters) {
+    _parameters = _becomeParentOf(parameters);
+  }
+
+  /**
+   * Return the name of the constructor to which this constructor will be
+   * redirected, or `null` if this is not a redirecting factory constructor.
+   */
+  ConstructorName get redirectedConstructor => _redirectedConstructor;
+
+  /**
+   * Set the name of the constructor to which this constructor will be
+   * redirected to the given [redirectedConstructor] name.
+   */
+  void set redirectedConstructor(ConstructorName redirectedConstructor) {
+    _redirectedConstructor = _becomeParentOf(redirectedConstructor);
+  }
+
+  /**
+   * Return the type of object being created. This can be different than the
+   * type in which the constructor is being declared if the constructor is the
+   * implementation of a factory constructor.
+   */
+  Identifier get returnType => _returnType;
+
+  /**
+   * Set the type of object being created to the given [typeName].
+   */
+  void set returnType(Identifier typeName) {
+    _returnType = _becomeParentOf(typeName);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitConstructorDeclaration(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_returnType, visitor);
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_parameters, visitor);
+    _initializers.accept(visitor);
+    _safelyVisitChild(_redirectedConstructor, visitor);
+    _safelyVisitChild(_body, visitor);
+  }
+}
+
+/**
+ * The initialization of a field within a constructor's initialization list.
+ *
+ * > fieldInitializer ::=
+ * >     ('this' '.')? [SimpleIdentifier] '=' [Expression]
+ */
+class ConstructorFieldInitializer extends ConstructorInitializer {
+  /**
+   * The token for the 'this' keyword, or `null` if there is no 'this' keyword.
+   */
+  Token thisKeyword;
+
+  /**
+   * The token for the period after the 'this' keyword, or `null` if there is no
+   * 'this' keyword.
+   */
+  Token period;
+
+  /**
+   * The name of the field being initialized.
+   */
+  SimpleIdentifier _fieldName;
+
+  /**
+   * The token for the equal sign between the field name and the expression.
+   */
+  Token equals;
+
+  /**
+   * The expression computing the value to which the field will be initialized.
+   */
+  Expression _expression;
+
+  /**
+   * Initialize a newly created field initializer to initialize the field with
+   * the given name to the value of the given expression. The [thisKeyword] and
+   * [period] can be `null` if the 'this' keyword was not specified.
+   */
+  ConstructorFieldInitializer(this.thisKeyword, this.period,
+      SimpleIdentifier fieldName, this.equals, Expression expression) {
+    _fieldName = _becomeParentOf(fieldName);
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get beginToken {
+    if (thisKeyword != null) {
+      return thisKeyword;
+    }
+    return _fieldName.beginToken;
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(thisKeyword)
+    ..add(period)
+    ..add(_fieldName)
+    ..add(equals)
+    ..add(_expression);
+
+  @override
+  Token get endToken => _expression.endToken;
+
+  /**
+   * Return the expression computing the value to which the field will be
+   * initialized.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression computing the value to which the field will be
+   * initialized to the given [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  /**
+   * Return the name of the field being initialized.
+   */
+  SimpleIdentifier get fieldName => _fieldName;
+
+  /**
+   * Set the name of the field being initialized to the given [identifier].
+   */
+  void set fieldName(SimpleIdentifier identifier) {
+    _fieldName = _becomeParentOf(identifier);
+  }
+
+  /**
+   * Return the token for the 'this' keyword, or `null` if there is no 'this'
+   * keyword.
+   */
+  @deprecated // Use "this.thisKeyword"
+  Token get keyword => thisKeyword;
+
+  /**
+   * Set the token for the 'this' keyword to the given [token].
+   */
+  @deprecated // Use "this.thisKeyword"
+  set keyword(Token token) {
+    thisKeyword = token;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitConstructorFieldInitializer(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_fieldName, visitor);
+    _safelyVisitChild(_expression, visitor);
+  }
+}
+
+/**
+ * A node that can occur in the initializer list of a constructor declaration.
+ *
+ * > constructorInitializer ::=
+ * >     [SuperConstructorInvocation]
+ * >   | [ConstructorFieldInitializer]
+ */
+abstract class ConstructorInitializer extends AstNode {}
+
+/**
+ * The name of the constructor.
+ *
+ * > constructorName ::=
+ * >     type ('.' identifier)?
+ */
+class ConstructorName extends AstNode {
+  /**
+   * The name of the type defining the constructor.
+   */
+  TypeName _type;
+
+  /**
+   * The token for the period before the constructor name, or `null` if the
+   * specified constructor is the unnamed constructor.
+   */
+  Token period;
+
+  /**
+   * The name of the constructor, or `null` if the specified constructor is the
+   * unnamed constructor.
+   */
+  SimpleIdentifier _name;
+
+  /**
+   * The element associated with this constructor name based on static type
+   * information, or `null` if the AST structure has not been resolved or if
+   * this constructor name could not be resolved.
+   */
+  ConstructorElement staticElement;
+
+  /**
+   * Initialize a newly created constructor name. The [period] and [name] can be
+   * `null` if the constructor being named is the unnamed constructor.
+   */
+  ConstructorName(TypeName type, this.period, SimpleIdentifier name) {
+    _type = _becomeParentOf(type);
+    _name = _becomeParentOf(name);
+  }
+
+  @override
+  Token get beginToken => _type.beginToken;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_type)..add(period)..add(_name);
+
+  @override
+  Token get endToken {
+    if (_name != null) {
+      return _name.endToken;
+    }
+    return _type.endToken;
+  }
+
+  /**
+   * Return the name of the constructor, or `null` if the specified constructor
+   * is the unnamed constructor.
+   */
+  SimpleIdentifier get name => _name;
+
+  /**
+   * Set the name of the constructor to the given [name].
+   */
+  void set name(SimpleIdentifier name) {
+    _name = _becomeParentOf(name);
+  }
+
+  /**
+   * Return the name of the type defining the constructor.
+   */
+  TypeName get type => _type;
+
+  /**
+   * Set the name of the type defining the constructor to the given [type] name.
+   */
+  void set type(TypeName type) {
+    _type = _becomeParentOf(type);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitConstructorName(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_type, visitor);
+    _safelyVisitChild(_name, visitor);
+  }
+}
+
+/**
+ * A continue statement.
+ *
+ * > continueStatement ::=
+ * >     'continue' [SimpleIdentifier]? ';'
+ */
+class ContinueStatement extends Statement {
+  /**
+   * The token representing the 'continue' keyword.
+   */
+  Token continueKeyword;
+
+  /**
+   * The label associated with the statement, or `null` if there is no label.
+   */
+  SimpleIdentifier _label;
+
+  /**
+   * The semicolon terminating the statement.
+   */
+  Token semicolon;
+
+  /**
+   * The AstNode which this continue statement is continuing to.  This will be
+   * either a Statement (in the case of continuing a loop) or a SwitchMember
+   * (in the case of continuing from one switch case to another).  Null if the
+   * AST has not yet been resolved or if the target could not be resolved.
+   * Note that if the source code has errors, the target may be invalid (e.g.
+   * the target may be in an enclosing function).
+   */
+  AstNode target;
+
+  /**
+   * Initialize a newly created continue statement. The [label] can be `null` if
+   * there is no label associated with the statement.
+   */
+  ContinueStatement(
+      this.continueKeyword, SimpleIdentifier label, this.semicolon) {
+    _label = _becomeParentOf(label);
+  }
+
+  @override
+  Token get beginToken => continueKeyword;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(continueKeyword)..add(_label)..add(semicolon);
+
+  @override
+  Token get endToken => semicolon;
+
+  /**
+   * Return the token for the 'continue' keyword, or `null` if there is no
+   * 'continue' keyword.
+   */
+  @deprecated // Use "this.continueKeyword"
+  Token get keyword => continueKeyword;
+
+  /**
+   * Set the token for the 'continue' keyword to the given [token].
+   */
+  @deprecated // Use "this.continueKeyword"
+  set keyword(Token token) {
+    continueKeyword = token;
+  }
+
+  /**
+   * Return the label associated with the statement, or `null` if there is no
+   * label.
+   */
+  SimpleIdentifier get label => _label;
+
+  /**
+   * Set the label associated with the statement to the given [identifier].
+   */
+  void set label(SimpleIdentifier identifier) {
+    _label = _becomeParentOf(identifier);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitContinueStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_label, visitor);
+  }
+}
+
+/**
+ * A node that represents the declaration of one or more names. Each declared
+ * name is visible within a name scope.
+ */
+abstract class Declaration extends AnnotatedNode {
+  /**
+   * Initialize a newly created declaration. Either or both of the [comment] and
+   * [metadata] can be `null` if the declaration does not have the corresponding
+   * attribute.
+   */
+  Declaration(Comment comment, List<Annotation> metadata)
+      : super(comment, metadata);
+
+  /**
+   * Return the element associated with this declaration, or `null` if either
+   * this node corresponds to a list of declarations or if the AST structure has
+   * not been resolved.
+   */
+  Element get element;
+}
+
+/**
+ * The declaration of a single identifier.
+ *
+ * > declaredIdentifier ::=
+ * >     [Annotation] finalConstVarOrType [SimpleIdentifier]
+ */
+class DeclaredIdentifier extends Declaration {
+  /**
+   * The token representing either the 'final', 'const' or 'var' keyword, or
+   * `null` if no keyword was used.
+   */
+  Token keyword;
+
+  /**
+   * The name of the declared type of the parameter, or `null` if the parameter
+   * does not have a declared type.
+   */
+  TypeName _type;
+
+  /**
+   * The name of the variable being declared.
+   */
+  SimpleIdentifier _identifier;
+
+  /**
+   * Initialize a newly created formal parameter. Either or both of the
+   * [comment] and [metadata] can be `null` if the declaration does not have the
+   * corresponding attribute. The [keyword] can be `null` if a type name is
+   * given. The [type] must be `null` if the keyword is 'var'.
+   */
+  DeclaredIdentifier(Comment comment, List<Annotation> metadata, this.keyword,
+      TypeName type, SimpleIdentifier identifier)
+      : super(comment, metadata) {
+    _type = _becomeParentOf(type);
+    _identifier = _becomeParentOf(identifier);
+  }
+
+  @override
+  Iterable get childEntities =>
+      super._childEntities..add(keyword)..add(_type)..add(_identifier);
+
+  @override
+  LocalVariableElement get element {
+    if (_identifier == null) {
+      return null;
+    }
+    return _identifier.staticElement as LocalVariableElement;
+  }
+
+  @override
+  Token get endToken => _identifier.endToken;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata {
+    if (keyword != null) {
+      return keyword;
+    } else if (_type != null) {
+      return _type.beginToken;
+    }
+    return _identifier.beginToken;
+  }
+
+  /**
+   * Return the name of the variable being declared.
+   */
+  SimpleIdentifier get identifier => _identifier;
+
+  /**
+   * Set the name of the variable being declared to the given [identifier].
+   */
+  void set identifier(SimpleIdentifier identifier) {
+    _identifier = _becomeParentOf(identifier);
+  }
+
+  /**
+   * Return `true` if this variable was declared with the 'const' modifier.
+   */
+  bool get isConst => (keyword is KeywordToken) &&
+      (keyword as KeywordToken).keyword == Keyword.CONST;
+
+  /**
+   * Return `true` if this variable was declared with the 'final' modifier.
+   * Variables that are declared with the 'const' modifier will return `false`
+   * even though they are implicitly final.
+   */
+  bool get isFinal => (keyword is KeywordToken) &&
+      (keyword as KeywordToken).keyword == Keyword.FINAL;
+
+  /**
+   * Return the name of the declared type of the parameter, or `null` if the
+   * parameter does not have a declared type.
+   */
+  TypeName get type => _type;
+
+  /**
+   * Set the name of the declared type of the parameter to the given [typeName].
+   */
+  void set type(TypeName typeName) {
+    _type = _becomeParentOf(typeName);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitDeclaredIdentifier(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_type, visitor);
+    _safelyVisitChild(_identifier, visitor);
+  }
+}
+
+/**
+ * A formal parameter with a default value. There are two kinds of parameters
+ * that are both represented by this class: named formal parameters and
+ * positional formal parameters.
+ *
+ * > defaultFormalParameter ::=
+ * >     [NormalFormalParameter] ('=' [Expression])?
+ * >
+ * > defaultNamedParameter ::=
+ * >     [NormalFormalParameter] (':' [Expression])?
+ */
+class DefaultFormalParameter extends FormalParameter {
+  /**
+   * The formal parameter with which the default value is associated.
+   */
+  NormalFormalParameter _parameter;
+
+  /**
+   * The kind of this parameter.
+   */
+  ParameterKind kind;
+
+  /**
+   * The token separating the parameter from the default value, or `null` if
+   * there is no default value.
+   */
+  Token separator;
+
+  /**
+   * The expression computing the default value for the parameter, or `null` if
+   * there is no default value.
+   */
+  Expression _defaultValue;
+
+  /**
+   * Initialize a newly created default formal parameter. The [separator] and
+   * [defaultValue] can be `null` if there is no default value.
+   */
+  DefaultFormalParameter(NormalFormalParameter parameter, this.kind,
+      this.separator, Expression defaultValue) {
+    _parameter = _becomeParentOf(parameter);
+    _defaultValue = _becomeParentOf(defaultValue);
+  }
+
+  @override
+  Token get beginToken => _parameter.beginToken;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_parameter)..add(separator)..add(_defaultValue);
+
+  /**
+   * Return the expression computing the default value for the parameter, or
+   * `null` if there is no default value.
+   */
+  Expression get defaultValue => _defaultValue;
+
+  /**
+   * Set the expression computing the default value for the parameter to the
+   * given [expression].
+   */
+  void set defaultValue(Expression expression) {
+    _defaultValue = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get endToken {
+    if (_defaultValue != null) {
+      return _defaultValue.endToken;
+    }
+    return _parameter.endToken;
+  }
+
+  @override
+  SimpleIdentifier get identifier => _parameter.identifier;
+
+  @override
+  bool get isConst => _parameter != null && _parameter.isConst;
+
+  @override
+  bool get isFinal => _parameter != null && _parameter.isFinal;
+
+  @override
+  NodeList<Annotation> get metadata => _parameter.metadata;
+
+  /**
+   * Return the formal parameter with which the default value is associated.
+   */
+  NormalFormalParameter get parameter => _parameter;
+
+  /**
+   * Set the formal parameter with which the default value is associated to the
+   * given [formalParameter].
+   */
+  void set parameter(NormalFormalParameter formalParameter) {
+    _parameter = _becomeParentOf(formalParameter);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitDefaultFormalParameter(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_parameter, visitor);
+    _safelyVisitChild(_defaultValue, visitor);
+  }
+}
+
+/**
+ * A recursive AST visitor that is used to run over [Expression]s to determine
+ * whether the expression is composed by at least one deferred
+ * [PrefixedIdentifier].
+ *
+ * See [PrefixedIdentifier.isDeferred].
+ */
+class DeferredLibraryReferenceDetector extends RecursiveAstVisitor<Object> {
+  /**
+   * A flag indicating whether an identifier from a deferred library has been
+   * found.
+   */
+  bool _result = false;
+
+  /**
+   * Return `true` if the visitor found a [PrefixedIdentifier] that returned
+   * `true` to the [PrefixedIdentifier.isDeferred] query.
+   */
+  bool get result => _result;
+
+  @override
+  Object visitPrefixedIdentifier(PrefixedIdentifier node) {
+    if (!_result) {
+      if (node.isDeferred) {
+        _result = true;
+      }
+    }
+    return null;
+  }
+}
+
+/**
+ * A node that represents a directive.
+ *
+ * > directive ::=
+ * >     [ExportDirective]
+ * >   | [ImportDirective]
+ * >   | [LibraryDirective]
+ * >   | [PartDirective]
+ * >   | [PartOfDirective]
+ */
+abstract class Directive extends AnnotatedNode {
+  /**
+   * The element associated with this directive, or `null` if the AST structure
+   * has not been resolved or if this directive could not be resolved.
+   */
+  Element element;
+
+  /**
+   * Initialize a newly create directive. Either or both of the [comment] and
+   * [metadata] can be `null` if the directive does not have the corresponding
+   * attribute.
+   */
+  Directive(Comment comment, List<Annotation> metadata)
+      : super(comment, metadata);
+
+  /**
+   * Return the token representing the keyword that introduces this directive
+   * ('import', 'export', 'library' or 'part').
+   */
+  Token get keyword;
+}
+
+/**
+ * A do statement.
+ *
+ * > doStatement ::=
+ * >     'do' [Statement] 'while' '(' [Expression] ')' ';'
+ */
+class DoStatement extends Statement {
+  /**
+   * The token representing the 'do' keyword.
+   */
+  Token doKeyword;
+
+  /**
+   * The body of the loop.
+   */
+  Statement _body;
+
+  /**
+   * The token representing the 'while' keyword.
+   */
+  Token whileKeyword;
+
+  /**
+   * The left parenthesis.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The condition that determines when the loop will terminate.
+   */
+  Expression _condition;
+
+  /**
+   * The right parenthesis.
+   */
+  Token rightParenthesis;
+
+  /**
+   * The semicolon terminating the statement.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created do loop.
+   */
+  DoStatement(this.doKeyword, Statement body, this.whileKeyword,
+      this.leftParenthesis, Expression condition, this.rightParenthesis,
+      this.semicolon) {
+    _body = _becomeParentOf(body);
+    _condition = _becomeParentOf(condition);
+  }
+
+  @override
+  Token get beginToken => doKeyword;
+
+  /**
+   * Return the body of the loop.
+   */
+  Statement get body => _body;
+
+  /**
+   * Set the body of the loop to the given [statement].
+   */
+  void set body(Statement statement) {
+    _body = _becomeParentOf(statement);
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(doKeyword)
+    ..add(_body)
+    ..add(whileKeyword)
+    ..add(leftParenthesis)
+    ..add(_condition)
+    ..add(rightParenthesis)
+    ..add(semicolon);
+
+  /**
+   * Return the condition that determines when the loop will terminate.
+   */
+  Expression get condition => _condition;
+
+  /**
+   * Set the condition that determines when the loop will terminate to the given
+   * [expression].
+   */
+  void set condition(Expression expression) {
+    _condition = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get endToken => semicolon;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitDoStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_body, visitor);
+    _safelyVisitChild(_condition, visitor);
+  }
+}
+
+/**
+ * A floating point literal expression.
+ *
+ * > doubleLiteral ::=
+ * >     decimalDigit+ ('.' decimalDigit*)? exponent?
+ * >   | '.' decimalDigit+ exponent?
+ * >
+ * > exponent ::=
+ * >     ('e' | 'E') ('+' | '-')? decimalDigit+
+ */
+class DoubleLiteral extends Literal {
+  /**
+   * The token representing the literal.
+   */
+  Token literal;
+
+  /**
+   * The value of the literal.
+   */
+  double value;
+
+  /**
+   * Initialize a newly created floating point literal.
+   */
+  DoubleLiteral(this.literal, this.value);
+
+  @override
+  Token get beginToken => literal;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(literal);
+
+  @override
+  Token get endToken => literal;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitDoubleLiteral(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+}
+
+/**
+ * An object used to locate the [Element] associated with a given [AstNode].
+ */
+class ElementLocator {
+  /**
+   * Return the element associated with the given [node], or `null` if there is
+   * no element associated with the node.
+   */
+  static Element locate(AstNode node) {
+    if (node == null) {
+      return null;
+    }
+    ElementLocator_ElementMapper mapper = new ElementLocator_ElementMapper();
+    return node.accept(mapper);
+  }
+
+  /**
+   * Return the element associated with the given [node], or `null` if there is
+   * no element associated with the node.
+   */
+  static Element locateWithOffset(AstNode node, int offset) {
+    // TODO(brianwilkerson) 'offset' is not used. Figure out what's going on:
+    // whether there's a bug or whether this method is unnecessary.
+    if (node == null) {
+      return null;
+    }
+    // try to get Element from node
+    Element nodeElement = locate(node);
+    if (nodeElement != null) {
+      return nodeElement;
+    }
+    // no Element
+    return null;
+  }
+}
+
+/**
+ * Visitor that maps nodes to elements.
+ */
+class ElementLocator_ElementMapper extends GeneralizingAstVisitor<Element> {
+  @override
+  Element visitAnnotation(Annotation node) => node.element;
+
+  @override
+  Element visitAssignmentExpression(AssignmentExpression node) =>
+      node.bestElement;
+
+  @override
+  Element visitBinaryExpression(BinaryExpression node) => node.bestElement;
+
+  @override
+  Element visitClassDeclaration(ClassDeclaration node) => node.element;
+
+  @override
+  Element visitCompilationUnit(CompilationUnit node) => node.element;
+
+  @override
+  Element visitConstructorDeclaration(ConstructorDeclaration node) =>
+      node.element;
+
+  @override
+  Element visitFunctionDeclaration(FunctionDeclaration node) => node.element;
+
+  @override
+  Element visitIdentifier(Identifier node) {
+    AstNode parent = node.parent;
+    // Type name in Annotation
+    if (parent is Annotation) {
+      Annotation annotation = parent;
+      if (identical(annotation.name, node) &&
+          annotation.constructorName == null) {
+        return annotation.element;
+      }
+    }
+    // Extra work to map Constructor Declarations to their associated
+    // Constructor Elements
+    if (parent is ConstructorDeclaration) {
+      ConstructorDeclaration decl = parent;
+      Identifier returnType = decl.returnType;
+      if (identical(returnType, node)) {
+        SimpleIdentifier name = decl.name;
+        if (name != null) {
+          return name.bestElement;
+        }
+        Element element = node.bestElement;
+        if (element is ClassElement) {
+          return element.unnamedConstructor;
+        }
+      }
+    }
+    if (parent is LibraryIdentifier) {
+      AstNode grandParent = parent.parent;
+      if (grandParent is PartOfDirective) {
+        Element element = grandParent.element;
+        if (element is LibraryElement) {
+          return element.definingCompilationUnit;
+        }
+      }
+    }
+    return node.bestElement;
+  }
+
+  @override
+  Element visitImportDirective(ImportDirective node) => node.element;
+
+  @override
+  Element visitIndexExpression(IndexExpression node) => node.bestElement;
+
+  @override
+  Element visitInstanceCreationExpression(InstanceCreationExpression node) =>
+      node.staticElement;
+
+  @override
+  Element visitLibraryDirective(LibraryDirective node) => node.element;
+
+  @override
+  Element visitMethodDeclaration(MethodDeclaration node) => node.element;
+
+  @override
+  Element visitMethodInvocation(MethodInvocation node) =>
+      node.methodName.bestElement;
+
+  @override
+  Element visitPostfixExpression(PostfixExpression node) => node.bestElement;
+
+  @override
+  Element visitPrefixedIdentifier(PrefixedIdentifier node) => node.bestElement;
+
+  @override
+  Element visitPrefixExpression(PrefixExpression node) => node.bestElement;
+
+  @override
+  Element visitStringLiteral(StringLiteral node) {
+    AstNode parent = node.parent;
+    if (parent is UriBasedDirective) {
+      return parent.uriElement;
+    }
+    return null;
+  }
+
+  @override
+  Element visitVariableDeclaration(VariableDeclaration node) => node.element;
+}
+
+/**
+ * An empty function body, which can only appear in constructors or abstract
+ * methods.
+ *
+ * > emptyFunctionBody ::=
+ * >     ';'
+ */
+class EmptyFunctionBody extends FunctionBody {
+  /**
+   * The token representing the semicolon that marks the end of the function
+   * body.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created function body.
+   */
+  EmptyFunctionBody(this.semicolon);
+
+  @override
+  Token get beginToken => semicolon;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(semicolon);
+
+  @override
+  Token get endToken => semicolon;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitEmptyFunctionBody(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // Empty function bodies have no children.
+  }
+}
+
+/**
+ * An empty statement.
+ *
+ * > emptyStatement ::=
+ * >     ';'
+ */
+class EmptyStatement extends Statement {
+  /**
+   * The semicolon terminating the statement.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created empty statement.
+   */
+  EmptyStatement(this.semicolon);
+
+  @override
+  Token get beginToken => semicolon;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(semicolon);
+
+  @override
+  Token get endToken => semicolon;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitEmptyStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+}
+
+/**
+ * The declaration of an enum constant.
+ */
+class EnumConstantDeclaration extends Declaration {
+  /**
+   * The name of the constant.
+   */
+  SimpleIdentifier _name;
+
+  /**
+   * Initialize a newly created enum constant declaration. Either or both of the
+   * [comment] and [metadata] can be `null` if the constant does not have the
+   * corresponding attribute. (Technically, enum constants cannot have metadata,
+   * but we allow it for consistency.)
+   */
+  EnumConstantDeclaration(
+      Comment comment, List<Annotation> metadata, SimpleIdentifier name)
+      : super(comment, metadata) {
+    _name = _becomeParentOf(name);
+  }
+
+  @override
+  Iterable get childEntities => super._childEntities..add(_name);
+
+  @override
+  FieldElement get element =>
+      _name == null ? null : (_name.staticElement as FieldElement);
+
+  @override
+  Token get endToken => _name.endToken;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata => _name.beginToken;
+
+  /**
+   * Return the name of the constant.
+   */
+  SimpleIdentifier get name => _name;
+
+  /**
+   * Set the name of the constant to the given [name].
+   */
+  void set name(SimpleIdentifier name) {
+    _name = _becomeParentOf(name);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitEnumConstantDeclaration(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_name, visitor);
+  }
+}
+
+/**
+ * The declaration of an enumeration.
+ *
+ * > enumType ::=
+ * >     metadata 'enum' [SimpleIdentifier] '{' [SimpleIdentifier] (',' [SimpleIdentifier])* (',')? '}'
+ */
+class EnumDeclaration extends NamedCompilationUnitMember {
+  /**
+   * The 'enum' keyword.
+   */
+  Token enumKeyword;
+
+  /**
+   * The left curly bracket.
+   */
+  Token leftBracket;
+
+  /**
+   * The enumeration constants being declared.
+   */
+  NodeList<EnumConstantDeclaration> _constants;
+
+  /**
+   * The right curly bracket.
+   */
+  Token rightBracket;
+
+  /**
+   * Initialize a newly created enumeration declaration. Either or both of the
+   * [comment] and [metadata] can be `null` if the declaration does not have the
+   * corresponding attribute. The list of [constants] must contain at least one
+   * value.
+   */
+  EnumDeclaration(Comment comment, List<Annotation> metadata, this.enumKeyword,
+      SimpleIdentifier name, this.leftBracket,
+      List<EnumConstantDeclaration> constants, this.rightBracket)
+      : super(comment, metadata, name) {
+    _constants = new NodeList<EnumConstantDeclaration>(this, constants);
+  }
+
+  @override
+  // TODO(brianwilkerson) Add commas?
+  Iterable get childEntities => super._childEntities
+    ..add(enumKeyword)
+    ..add(_name)
+    ..add(leftBracket)
+    ..addAll(_constants)
+    ..add(rightBracket);
+
+  /**
+   * Return the enumeration constants being declared.
+   */
+  NodeList<EnumConstantDeclaration> get constants => _constants;
+
+  @override
+  ClassElement get element =>
+      _name != null ? (_name.staticElement as ClassElement) : null;
+
+  @override
+  Token get endToken => rightBracket;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata => enumKeyword;
+
+  /**
+   * Return the token for the 'enum' keyword, or `null` if there is no
+   * 'enum' keyword.
+   */
+  @deprecated // Use "this.enumKeyword"
+  Token get keyword => enumKeyword;
+
+  /**
+   * Set the token for the 'enum' keyword to the given [token].
+   */
+  @deprecated // Use "this.enumKeyword"
+  set keyword(Token token) {
+    enumKeyword = token;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitEnumDeclaration(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_name, visitor);
+    _constants.accept(visitor);
+  }
+}
+
+/**
+ * Ephemeral identifiers are created as needed to mimic the presence of an empty
+ * identifier.
+ */
+class EphemeralIdentifier extends SimpleIdentifier {
+  EphemeralIdentifier(AstNode parent, int location)
+      : super(new StringToken(TokenType.IDENTIFIER, "", location)) {
+    parent._becomeParentOf(this);
+  }
+}
+
+/**
+ * An export directive.
+ *
+ * > exportDirective ::=
+ * >     [Annotation] 'export' [StringLiteral] [Combinator]* ';'
+ */
+class ExportDirective extends NamespaceDirective {
+  /**
+   * Initialize a newly created export directive. Either or both of the
+   * [comment] and [metadata] can be `null` if the directive does not have the
+   * corresponding attribute. The list of [combinators] can be `null` if there
+   * are no combinators.
+   */
+  ExportDirective(Comment comment, List<Annotation> metadata, Token keyword,
+      StringLiteral libraryUri, List<Combinator> combinators, Token semicolon)
+      : super(comment, metadata, keyword, libraryUri, combinators, semicolon);
+
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(_uri)
+    ..addAll(combinators)
+    ..add(semicolon);
+
+  @override
+  ExportElement get element => super.element as ExportElement;
+
+  @override
+  LibraryElement get uriElement {
+    if (element != null) {
+      return element.exportedLibrary;
+    }
+    return null;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitExportDirective(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    combinators.accept(visitor);
+  }
+}
+
+/**
+ * A node that represents an expression.
+ *
+ * > expression ::=
+ * >     [AssignmentExpression]
+ * >   | [ConditionalExpression] cascadeSection*
+ * >   | [ThrowExpression]
+ */
+abstract class Expression extends AstNode {
+  /**
+   * An empty list of expressions.
+   */
+  @deprecated // Use "Expression.EMPTY_LIST"
+  static const List<Expression> EMPTY_ARRAY = EMPTY_LIST;
+
+  /**
+   * An empty list of expressions.
+   */
+  static const List<Expression> EMPTY_LIST = const <Expression>[];
+
+  /**
+   * The static type of this expression, or `null` if the AST structure has not
+   * been resolved.
+   */
+  DartType staticType;
+
+  /**
+   * The propagated type of this expression, or `null` if type propagation has
+   * not been performed on the AST structure.
+   */
+  DartType propagatedType;
+
+  /**
+   * Return the best parameter element information available for this
+   * expression. If type propagation was able to find a better parameter element
+   * than static analysis, that type will be returned. Otherwise, the result of
+   * static analysis will be returned.
+   */
+  ParameterElement get bestParameterElement {
+    ParameterElement propagatedElement = propagatedParameterElement;
+    if (propagatedElement != null) {
+      return propagatedElement;
+    }
+    return staticParameterElement;
+  }
+
+  /**
+   * Return the best type information available for this expression. If type
+   * propagation was able to find a better type than static analysis, that type
+   * will be returned. Otherwise, the result of static analysis will be
+   * returned. If no type analysis has been performed, then the type 'dynamic'
+   * will be returned.
+   */
+  DartType get bestType {
+    if (propagatedType != null) {
+      return propagatedType;
+    } else if (staticType != null) {
+      return staticType;
+    }
+    return DynamicTypeImpl.instance;
+  }
+
+  /**
+   * Return `true` if this expression is syntactically valid for the LHS of an
+   * [AssignmentExpression].
+   */
+  bool get isAssignable => false;
+
+  /**
+   * Return the precedence of this expression. The precedence is a positive
+   * integer value that defines how the source code is parsed into an AST. For
+   * example `a * b + c` is parsed as `(a * b) + c` because the precedence of
+   * `*` is greater than the precedence of `+`.
+   *
+   * Clients should not assume that returned values will stay the same, they
+   * might change as result of specification change. Only relative order should
+   * be used.
+   */
+  int get precedence;
+
+  /**
+   * If this expression is an argument to an invocation, and the AST structure
+   * has been resolved, and the function being invoked is known based on
+   * propagated type information, and this expression corresponds to one of the
+   * parameters of the function being invoked, then return the parameter element
+   * representing the parameter to which the value of this expression will be
+   * bound. Otherwise, return `null`.
+   */
+  ParameterElement get propagatedParameterElement {
+    AstNode parent = this.parent;
+    if (parent is ArgumentList) {
+      return parent._getPropagatedParameterElementFor(this);
+    } else if (parent is IndexExpression) {
+      IndexExpression indexExpression = parent;
+      if (identical(indexExpression.index, this)) {
+        return indexExpression._propagatedParameterElementForIndex;
+      }
+    } else if (parent is BinaryExpression) {
+      BinaryExpression binaryExpression = parent;
+      if (identical(binaryExpression.rightOperand, this)) {
+        return binaryExpression._propagatedParameterElementForRightOperand;
+      }
+    } else if (parent is AssignmentExpression) {
+      AssignmentExpression assignmentExpression = parent;
+      if (identical(assignmentExpression.rightHandSide, this)) {
+        return assignmentExpression._propagatedParameterElementForRightHandSide;
+      }
+    } else if (parent is PrefixExpression) {
+      return parent._propagatedParameterElementForOperand;
+    } else if (parent is PostfixExpression) {
+      return parent._propagatedParameterElementForOperand;
+    }
+    return null;
+  }
+
+  /**
+   * If this expression is an argument to an invocation, and the AST structure
+   * has been resolved, and the function being invoked is known based on static
+   * type information, and this expression corresponds to one of the parameters
+   * of the function being invoked, then return the parameter element
+   * representing the parameter to which the value of this expression will be
+   * bound. Otherwise, return `null`.
+   */
+  ParameterElement get staticParameterElement {
+    AstNode parent = this.parent;
+    if (parent is ArgumentList) {
+      return parent._getStaticParameterElementFor(this);
+    } else if (parent is IndexExpression) {
+      IndexExpression indexExpression = parent;
+      if (identical(indexExpression.index, this)) {
+        return indexExpression._staticParameterElementForIndex;
+      }
+    } else if (parent is BinaryExpression) {
+      BinaryExpression binaryExpression = parent;
+      if (identical(binaryExpression.rightOperand, this)) {
+        return binaryExpression._staticParameterElementForRightOperand;
+      }
+    } else if (parent is AssignmentExpression) {
+      AssignmentExpression assignmentExpression = parent;
+      if (identical(assignmentExpression.rightHandSide, this)) {
+        return assignmentExpression._staticParameterElementForRightHandSide;
+      }
+    } else if (parent is PrefixExpression) {
+      return parent._staticParameterElementForOperand;
+    } else if (parent is PostfixExpression) {
+      return parent._staticParameterElementForOperand;
+    }
+    return null;
+  }
+}
+
+/**
+ * A function body consisting of a single expression.
+ *
+ * > expressionFunctionBody ::=
+ * >     'async'? '=>' [Expression] ';'
+ */
+class ExpressionFunctionBody extends FunctionBody {
+  /**
+   * The token representing the 'async' keyword, or `null` if there is no such
+   * keyword.
+   */
+  Token keyword;
+
+  /**
+   * The token introducing the expression that represents the body of the
+   * function.
+   */
+  Token functionDefinition;
+
+  /**
+   * The expression representing the body of the function.
+   */
+  Expression _expression;
+
+  /**
+   * The semicolon terminating the statement.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created function body consisting of a block of
+   * statements. The [keyword] can be `null` if the function body is not an
+   * async function body.
+   */
+  ExpressionFunctionBody(this.keyword, this.functionDefinition,
+      Expression expression, this.semicolon) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get beginToken {
+    if (keyword != null) {
+      return keyword;
+    }
+    return functionDefinition;
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(keyword)
+    ..add(functionDefinition)
+    ..add(_expression)
+    ..add(semicolon);
+
+  @override
+  Token get endToken {
+    if (semicolon != null) {
+      return semicolon;
+    }
+    return _expression.endToken;
+  }
+
+  /**
+   * Return the expression representing the body of the function.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression representing the body of the function to the given
+   * [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  bool get isAsynchronous => keyword != null;
+
+  @override
+  bool get isSynchronous => keyword == null;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitExpressionFunctionBody(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+  }
+}
+
+/**
+ * An expression used as a statement.
+ *
+ * > expressionStatement ::=
+ * >     [Expression]? ';'
+ */
+class ExpressionStatement extends Statement {
+  /**
+   * The expression that comprises the statement.
+   */
+  Expression _expression;
+
+  /**
+   * The semicolon terminating the statement, or `null` if the expression is a
+   * function expression and therefore isn't followed by a semicolon.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created expression statement.
+   */
+  ExpressionStatement(Expression expression, this.semicolon) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get beginToken => _expression.beginToken;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_expression)..add(semicolon);
+
+  @override
+  Token get endToken {
+    if (semicolon != null) {
+      return semicolon;
+    }
+    return _expression.endToken;
+  }
+
+  /**
+   * Return the expression that comprises the statement.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression that comprises the statement to the given [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  bool get isSynthetic => _expression.isSynthetic && semicolon.isSynthetic;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitExpressionStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+  }
+}
+
+/**
+ * The "extends" clause in a class declaration.
+ *
+ * > extendsClause ::=
+ * >     'extends' [TypeName]
+ */
+class ExtendsClause extends AstNode {
+  /**
+   * The token representing the 'extends' keyword.
+   */
+  Token extendsKeyword;
+
+  /**
+   * The name of the class that is being extended.
+   */
+  TypeName _superclass;
+
+  /**
+   * Initialize a newly created extends clause.
+   */
+  ExtendsClause(this.extendsKeyword, TypeName superclass) {
+    _superclass = _becomeParentOf(superclass);
+  }
+
+  @override
+  Token get beginToken => extendsKeyword;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(extendsKeyword)..add(_superclass);
+
+  @override
+  Token get endToken => _superclass.endToken;
+
+  /**
+   * Return the token for the 'extends' keyword.
+   */
+  @deprecated // Use "this.extendsKeyword"
+  Token get keyword => extendsKeyword;
+
+  /**
+   * Set the token for the 'extends' keyword to the given [token].
+   */
+  @deprecated // Use "this.extendsKeyword"
+  set keyword(Token token) {
+    extendsKeyword = token;
+  }
+
+  /**
+   * Return the name of the class that is being extended.
+   */
+  TypeName get superclass => _superclass;
+
+  /**
+   * Set the name of the class that is being extended to the given [name].
+   */
+  void set superclass(TypeName name) {
+    _superclass = _becomeParentOf(name);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitExtendsClause(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_superclass, visitor);
+  }
+}
+
+/**
+ * The declaration of one or more fields of the same type.
+ *
+ * > fieldDeclaration ::=
+ * >     'static'? [VariableDeclarationList] ';'
+ */
+class FieldDeclaration extends ClassMember {
+  /**
+   * The token representing the 'static' keyword, or `null` if the fields are
+   * not static.
+   */
+  Token staticKeyword;
+
+  /**
+   * The fields being declared.
+   */
+  VariableDeclarationList _fieldList;
+
+  /**
+   * The semicolon terminating the declaration.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created field declaration. Either or both of the
+   * [comment] and [metadata] can be `null` if the declaration does not have the
+   * corresponding attribute. The [staticKeyword] can be `null` if the field is
+   * not a static field.
+   */
+  FieldDeclaration(Comment comment, List<Annotation> metadata,
+      this.staticKeyword, VariableDeclarationList fieldList, this.semicolon)
+      : super(comment, metadata) {
+    _fieldList = _becomeParentOf(fieldList);
+  }
+
+  @override
+  Iterable get childEntities =>
+      super._childEntities..add(staticKeyword)..add(_fieldList)..add(semicolon);
+
+  @override
+  Element get element => null;
+
+  @override
+  Token get endToken => semicolon;
+
+  /**
+   * Return the fields being declared.
+   */
+  VariableDeclarationList get fields => _fieldList;
+
+  /**
+   * Set the fields being declared to the given list of [fields].
+   */
+  void set fields(VariableDeclarationList fields) {
+    _fieldList = _becomeParentOf(fields);
+  }
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata {
+    if (staticKeyword != null) {
+      return staticKeyword;
+    }
+    return _fieldList.beginToken;
+  }
+
+  /**
+   * Return `true` if the fields are declared to be static.
+   */
+  bool get isStatic => staticKeyword != null;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitFieldDeclaration(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_fieldList, visitor);
+  }
+}
+
+/**
+ * A field formal parameter.
+ *
+ * > fieldFormalParameter ::=
+ * >     ('final' [TypeName] | 'const' [TypeName] | 'var' | [TypeName])?
+ * >     'this' '.' [SimpleIdentifier] ([TypeParameterList]? [FormalParameterList])?
+ */
+class FieldFormalParameter extends NormalFormalParameter {
+  /**
+   * The token representing either the 'final', 'const' or 'var' keyword, or
+   * `null` if no keyword was used.
+   */
+  Token keyword;
+
+  /**
+   * The name of the declared type of the parameter, or `null` if the parameter
+   * does not have a declared type.
+   */
+  TypeName _type;
+
+  /**
+   * The token representing the 'this' keyword.
+   */
+  Token thisKeyword;
+
+  /**
+   * The token representing the period.
+   */
+  Token period;
+
+  /**
+   * The type parameters associated with the method, or `null` if the method is
+   * not a generic method.
+   */
+  TypeParameterList _typeParameters;
+
+  /**
+   * The parameters of the function-typed parameter, or `null` if this is not a
+   * function-typed field formal parameter.
+   */
+  FormalParameterList _parameters;
+
+  /**
+   * Initialize a newly created formal parameter. Either or both of the
+   * [comment] and [metadata] can be `null` if the parameter does not have the
+   * corresponding attribute. The [keyword] can be `null` if there is a type.
+   * The [type] must be `null` if the keyword is 'var'. The [thisKeyword] and
+   * [period] can be `null` if the keyword 'this' was not provided.  The
+   * [parameters] can be `null` if this is not a function-typed field formal
+   * parameter.
+   */
+  FieldFormalParameter(Comment comment, List<Annotation> metadata, this.keyword,
+      TypeName type, this.thisKeyword, this.period, SimpleIdentifier identifier,
+      TypeParameterList typeParameters, FormalParameterList parameters)
+      : super(comment, metadata, identifier) {
+    _type = _becomeParentOf(type);
+    _typeParameters = _becomeParentOf(typeParameters);
+    _parameters = _becomeParentOf(parameters);
+  }
+
+  @override
+  Token get beginToken {
+    if (keyword != null) {
+      return keyword;
+    } else if (_type != null) {
+      return _type.beginToken;
+    }
+    return thisKeyword;
+  }
+
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(keyword)
+    ..add(_type)
+    ..add(thisKeyword)
+    ..add(period)
+    ..add(identifier)
+    ..add(_parameters);
+
+  @override
+  Token get endToken {
+    if (_parameters != null) {
+      return _parameters.endToken;
+    }
+    return identifier.endToken;
+  }
+
+  @override
+  bool get isConst => (keyword is KeywordToken) &&
+      (keyword as KeywordToken).keyword == Keyword.CONST;
+
+  @override
+  bool get isFinal => (keyword is KeywordToken) &&
+      (keyword as KeywordToken).keyword == Keyword.FINAL;
+
+  /**
+   * Return the parameters of the function-typed parameter, or `null` if this is
+   * not a function-typed field formal parameter.
+   */
+  FormalParameterList get parameters => _parameters;
+
+  /**
+   * Set the parameters of the function-typed parameter to the given
+   * [parameters].
+   */
+  void set parameters(FormalParameterList parameters) {
+    _parameters = _becomeParentOf(parameters);
+  }
+
+  /**
+   * Return the token representing the 'this' keyword.
+   */
+  @deprecated // Use "this.thisKeyword"
+  Token get thisToken => thisKeyword;
+
+  /**
+   * Set the token representing the 'this' keyword to the given [token].
+   */
+  @deprecated // Use "this.thisKeyword"
+  set thisToken(Token token) {
+    thisKeyword = token;
+  }
+
+  /**
+   * Return the name of the declared type of the parameter, or `null` if the
+   * parameter does not have a declared type. Note that if this is a
+   * function-typed field formal parameter this is the return type of the
+   * function.
+   */
+  TypeName get type => _type;
+
+  /**
+   * Set the name of the declared type of the parameter to the given [typeName].
+   */
+  void set type(TypeName typeName) {
+    _type = _becomeParentOf(typeName);
+  }
+
+  /**
+   * Return the type parameters associated with this method, or `null` if this
+   * method is not a generic method.
+   */
+  TypeParameterList get typeParameters => _typeParameters;
+
+  /**
+   * Set the type parameters associated with this method to the given
+   * [typeParameters].
+   */
+  void set typeParameters(TypeParameterList typeParameters) {
+    _typeParameters = _becomeParentOf(typeParameters);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitFieldFormalParameter(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_type, visitor);
+    _safelyVisitChild(identifier, visitor);
+    _safelyVisitChild(_typeParameters, visitor);
+    _safelyVisitChild(_parameters, visitor);
+  }
+}
+
+/**
+ * A for-each statement.
+ *
+ * > forEachStatement ::=
+ * >     'await'? 'for' '(' [DeclaredIdentifier] 'in' [Expression] ')' [Block]
+ * >   | 'await'? 'for' '(' [SimpleIdentifier] 'in' [Expression] ')' [Block]
+ */
+class ForEachStatement extends Statement {
+  /**
+   * The token representing the 'await' keyword, or `null` if there is no
+   * 'await' keyword.
+   */
+  Token awaitKeyword;
+
+  /**
+   * The token representing the 'for' keyword.
+   */
+  Token forKeyword;
+
+  /**
+   * The left parenthesis.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The declaration of the loop variable, or `null` if the loop variable is a
+   * simple identifier.
+   */
+  DeclaredIdentifier _loopVariable;
+
+  /**
+   * The loop variable, or `null` if the loop variable is declared in the 'for'.
+   */
+  SimpleIdentifier _identifier;
+
+  /**
+   * The token representing the 'in' keyword.
+   */
+  Token inKeyword;
+
+  /**
+   * The expression evaluated to produce the iterator.
+   */
+  Expression _iterable;
+
+  /**
+   * The right parenthesis.
+   */
+  Token rightParenthesis;
+
+  /**
+   * The body of the loop.
+   */
+  Statement _body;
+
+  /**
+   * Initialize a newly created for-each statement. The [awaitKeyword] can be
+   * `null` if this is not an asynchronous for loop.
+   */
+  @deprecated // Use new ForEachStatement.withDeclaration(...)
+  ForEachStatement.con1(this.awaitKeyword, this.forKeyword,
+      this.leftParenthesis, DeclaredIdentifier loopVariable, this.inKeyword,
+      Expression iterator, this.rightParenthesis, Statement body) {
+    _loopVariable = _becomeParentOf(loopVariable);
+    _iterable = _becomeParentOf(iterator);
+    _body = _becomeParentOf(body);
+  }
+
+  /**
+   * Initialize a newly created for-each statement. The [awaitKeyword] can be
+   * `null` if this is not an asynchronous for loop.
+   */
+  @deprecated // Use new ForEachStatement.withReference(...)
+  ForEachStatement.con2(this.awaitKeyword, this.forKeyword,
+      this.leftParenthesis, SimpleIdentifier identifier, this.inKeyword,
+      Expression iterator, this.rightParenthesis, Statement body) {
+    _identifier = _becomeParentOf(identifier);
+    _iterable = _becomeParentOf(iterator);
+    _body = _becomeParentOf(body);
+  }
+
+  /**
+   * Initialize a newly created for-each statement whose loop control variable
+   * is declared internally (in the for-loop part). The [awaitKeyword] can be
+   * `null` if this is not an asynchronous for loop.
+   */
+  ForEachStatement.withDeclaration(this.awaitKeyword, this.forKeyword,
+      this.leftParenthesis, DeclaredIdentifier loopVariable, this.inKeyword,
+      Expression iterator, this.rightParenthesis, Statement body) {
+    _loopVariable = _becomeParentOf(loopVariable);
+    _iterable = _becomeParentOf(iterator);
+    _body = _becomeParentOf(body);
+  }
+
+  /**
+   * Initialize a newly created for-each statement whose loop control variable
+   * is declared outside the for loop. The [awaitKeyword] can be `null` if this
+   * is not an asynchronous for loop.
+   */
+  ForEachStatement.withReference(this.awaitKeyword, this.forKeyword,
+      this.leftParenthesis, SimpleIdentifier identifier, this.inKeyword,
+      Expression iterator, this.rightParenthesis, Statement body) {
+    _identifier = _becomeParentOf(identifier);
+    _iterable = _becomeParentOf(iterator);
+    _body = _becomeParentOf(body);
+  }
+
+  @override
+  Token get beginToken => forKeyword;
+
+  /**
+   * Return the body of the loop.
+   */
+  Statement get body => _body;
+
+  /**
+   * Set the body of the loop to the given [statement].
+   */
+  void set body(Statement statement) {
+    _body = _becomeParentOf(statement);
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(awaitKeyword)
+    ..add(forKeyword)
+    ..add(leftParenthesis)
+    ..add(_loopVariable)
+    ..add(_identifier)
+    ..add(inKeyword)
+    ..add(_iterable)
+    ..add(rightParenthesis)
+    ..add(_body);
+
+  @override
+  Token get endToken => _body.endToken;
+
+  /**
+   * Return the loop variable, or `null` if the loop variable is declared in the
+   * 'for'.
+   */
+  SimpleIdentifier get identifier => _identifier;
+
+  /**
+   * Set the loop variable to the given [identifier].
+   */
+  void set identifier(SimpleIdentifier identifier) {
+    _identifier = _becomeParentOf(identifier);
+  }
+
+  /**
+   * Return the expression evaluated to produce the iterator.
+   */
+  Expression get iterable => _iterable;
+
+  /**
+   * Set the expression evaluated to produce the iterator to the given
+   * [expression].
+   */
+  void set iterable(Expression expression) {
+    _iterable = _becomeParentOf(expression);
+  }
+
+  /**
+   * Return the expression evaluated to produce the iterator.
+   */
+  @deprecated // Use "this.iterable"
+  Expression get iterator => iterable;
+
+  /**
+   * Return the declaration of the loop variable, or `null` if the loop variable
+   * is a simple identifier.
+   */
+  DeclaredIdentifier get loopVariable => _loopVariable;
+
+  /**
+   * Set the declaration of the loop variable to the given [variable].
+   */
+  void set loopVariable(DeclaredIdentifier variable) {
+    _loopVariable = _becomeParentOf(variable);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitForEachStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_loopVariable, visitor);
+    _safelyVisitChild(_identifier, visitor);
+    _safelyVisitChild(_iterable, visitor);
+    _safelyVisitChild(_body, visitor);
+  }
+}
+
+/**
+ * A node representing a parameter to a function.
+ *
+ * > formalParameter ::=
+ * >     [NormalFormalParameter]
+ * >   | [DefaultFormalParameter]
+ */
+abstract class FormalParameter extends AstNode {
+  /**
+   * Return the element representing this parameter, or `null` if this parameter
+   * has not been resolved.
+   */
+  ParameterElement get element {
+    SimpleIdentifier identifier = this.identifier;
+    if (identifier == null) {
+      return null;
+    }
+    return identifier.staticElement as ParameterElement;
+  }
+
+  /**
+   * Return the name of the parameter being declared.
+   */
+  SimpleIdentifier get identifier;
+
+  /**
+   * Return `true` if this parameter was declared with the 'const' modifier.
+   */
+  bool get isConst;
+
+  /**
+   * Return `true` if this parameter was declared with the 'final' modifier.
+   * Parameters that are declared with the 'const' modifier will return `false`
+   * even though they are implicitly final.
+   */
+  bool get isFinal;
+
+  /**
+   * Return the kind of this parameter.
+   */
+  ParameterKind get kind;
+
+  /**
+   * Return the annotations associated with this parameter.
+   */
+  NodeList<Annotation> get metadata;
+}
+
+/**
+ * The formal parameter list of a method declaration, function declaration, or
+ * function type alias.
+ *
+ * While the grammar requires all optional formal parameters to follow all of
+ * the normal formal parameters and at most one grouping of optional formal
+ * parameters, this class does not enforce those constraints. All parameters are
+ * flattened into a single list, which can have any or all kinds of parameters
+ * (normal, named, and positional) in any order.
+ *
+ * > formalParameterList ::=
+ * >     '(' ')'
+ * >   | '(' normalFormalParameters (',' optionalFormalParameters)? ')'
+ * >   | '(' optionalFormalParameters ')'
+ * >
+ * > normalFormalParameters ::=
+ * >     [NormalFormalParameter] (',' [NormalFormalParameter])*
+ * >
+ * > optionalFormalParameters ::=
+ * >     optionalPositionalFormalParameters
+ * >   | namedFormalParameters
+ * >
+ * > optionalPositionalFormalParameters ::=
+ * >     '[' [DefaultFormalParameter] (',' [DefaultFormalParameter])* ']'
+ * >
+ * > namedFormalParameters ::=
+ * >     '{' [DefaultFormalParameter] (',' [DefaultFormalParameter])* '}'
+ */
+class FormalParameterList extends AstNode {
+  /**
+   * The left parenthesis.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The parameters associated with the method.
+   */
+  NodeList<FormalParameter> _parameters;
+
+  /**
+   * The left square bracket ('[') or left curly brace ('{') introducing the
+   * optional parameters, or `null` if there are no optional parameters.
+   */
+  Token leftDelimiter;
+
+  /**
+   * The right square bracket (']') or right curly brace ('}') terminating the
+   * optional parameters, or `null` if there are no optional parameters.
+   */
+  Token rightDelimiter;
+
+  /**
+   * The right parenthesis.
+   */
+  Token rightParenthesis;
+
+  /**
+   * Initialize a newly created parameter list. The list of [parameters] can be
+   * `null` if there are no parameters. The [leftDelimiter] and [rightDelimiter]
+   * can be `null` if there are no optional parameters.
+   */
+  FormalParameterList(this.leftParenthesis, List<FormalParameter> parameters,
+      this.leftDelimiter, this.rightDelimiter, this.rightParenthesis) {
+    _parameters = new NodeList<FormalParameter>(this, parameters);
+  }
+
+  @override
+  Token get beginToken => leftParenthesis;
+
+  @override
+  Iterable get childEntities {
+    // TODO(paulberry): include commas.
+    ChildEntities result = new ChildEntities()..add(leftParenthesis);
+    bool leftDelimiterNeeded = leftDelimiter != null;
+    for (FormalParameter parameter in _parameters) {
+      if (leftDelimiterNeeded && leftDelimiter.offset < parameter.offset) {
+        result.add(leftDelimiter);
+        leftDelimiterNeeded = false;
+      }
+      result.add(parameter);
+    }
+    return result..add(rightDelimiter)..add(rightParenthesis);
+  }
+
+  @override
+  Token get endToken => rightParenthesis;
+
+  /**
+   * Return a list containing the elements representing the parameters in this
+   * list. The list will contain `null`s if the parameters in this list have not
+   * been resolved.
+   */
+  List<ParameterElement> get parameterElements {
+    int count = _parameters.length;
+    List<ParameterElement> types = new List<ParameterElement>(count);
+    for (int i = 0; i < count; i++) {
+      types[i] = _parameters[i].element;
+    }
+    return types;
+  }
+
+  /**
+   * Return the parameters associated with the method.
+   */
+  NodeList<FormalParameter> get parameters => _parameters;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitFormalParameterList(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _parameters.accept(visitor);
+  }
+}
+
+/**
+ * A for statement.
+ *
+ * > forStatement ::=
+ * >     'for' '(' forLoopParts ')' [Statement]
+ * >
+ * > forLoopParts ::=
+ * >     forInitializerStatement ';' [Expression]? ';' [Expression]?
+ * >
+ * > forInitializerStatement ::=
+ * >     [DefaultFormalParameter]
+ * >   | [Expression]?
+ */
+class ForStatement extends Statement {
+  /**
+   * The token representing the 'for' keyword.
+   */
+  Token forKeyword;
+
+  /**
+   * The left parenthesis.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The declaration of the loop variables, or `null` if there are no variables.
+   * Note that a for statement cannot have both a variable list and an
+   * initialization expression, but can validly have neither.
+   */
+  VariableDeclarationList _variableList;
+
+  /**
+   * The initialization expression, or `null` if there is no initialization
+   * expression. Note that a for statement cannot have both a variable list and
+   * an initialization expression, but can validly have neither.
+   */
+  Expression _initialization;
+
+  /**
+   * The semicolon separating the initializer and the condition.
+   */
+  Token leftSeparator;
+
+  /**
+   * The condition used to determine when to terminate the loop, or `null` if
+   * there is no condition.
+   */
+  Expression _condition;
+
+  /**
+   * The semicolon separating the condition and the updater.
+   */
+  Token rightSeparator;
+
+  /**
+   * The list of expressions run after each execution of the loop body.
+   */
+  NodeList<Expression> _updaters;
+
+  /**
+   * The right parenthesis.
+   */
+  Token rightParenthesis;
+
+  /**
+   * The body of the loop.
+   */
+  Statement _body;
+
+  /**
+   * Initialize a newly created for statement. Either the [variableList] or the
+   * [initialization] must be `null`. Either the [condition] and the list of
+   * [updaters] can be `null` if the loop does not have the corresponding
+   * attribute.
+   */
+  ForStatement(this.forKeyword, this.leftParenthesis,
+      VariableDeclarationList variableList, Expression initialization,
+      this.leftSeparator, Expression condition, this.rightSeparator,
+      List<Expression> updaters, this.rightParenthesis, Statement body) {
+    _variableList = _becomeParentOf(variableList);
+    _initialization = _becomeParentOf(initialization);
+    _condition = _becomeParentOf(condition);
+    _updaters = new NodeList<Expression>(this, updaters);
+    _body = _becomeParentOf(body);
+  }
+
+  @override
+  Token get beginToken => forKeyword;
+
+  /**
+   * Return the body of the loop.
+   */
+  Statement get body => _body;
+
+  /**
+   * Set the body of the loop to the given [statement].
+   */
+  void set body(Statement statement) {
+    _body = _becomeParentOf(statement);
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(forKeyword)
+    ..add(leftParenthesis)
+    ..add(_variableList)
+    ..add(_initialization)
+    ..add(leftSeparator)
+    ..add(_condition)
+    ..add(rightSeparator)
+    ..addAll(_updaters)
+    ..add(rightParenthesis)
+    ..add(_body);
+
+  /**
+   * Return the condition used to determine when to terminate the loop, or
+   * `null` if there is no condition.
+   */
+  Expression get condition => _condition;
+
+  /**
+   * Set the condition used to determine when to terminate the loop to the given
+   * [expression].
+   */
+  void set condition(Expression expression) {
+    _condition = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get endToken => _body.endToken;
+
+  /**
+   * Return the initialization expression, or `null` if there is no
+   * initialization expression.
+   */
+  Expression get initialization => _initialization;
+
+  /**
+   * Set the initialization expression to the given [expression].
+   */
+  void set initialization(Expression initialization) {
+    _initialization = _becomeParentOf(initialization);
+  }
+
+  /**
+   * Return the list of expressions run after each execution of the loop body.
+   */
+  NodeList<Expression> get updaters => _updaters;
+
+  /**
+   * Return the declaration of the loop variables, or `null` if there are no
+   * variables.
+   */
+  VariableDeclarationList get variables => _variableList;
+
+  /**
+   * Set the declaration of the loop variables to the given [variableList].
+   */
+  void set variables(VariableDeclarationList variableList) {
+    _variableList = _becomeParentOf(variableList);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitForStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_variableList, visitor);
+    _safelyVisitChild(_initialization, visitor);
+    _safelyVisitChild(_condition, visitor);
+    _updaters.accept(visitor);
+    _safelyVisitChild(_body, visitor);
+  }
+}
+
+/**
+ * A node representing the body of a function or method.
+ *
+ * > functionBody ::=
+ * >     [BlockFunctionBody]
+ * >   | [EmptyFunctionBody]
+ * >   | [ExpressionFunctionBody]
+ */
+abstract class FunctionBody extends AstNode {
+  /**
+   * Return `true` if this function body is asynchronous.
+   */
+  bool get isAsynchronous => false;
+
+  /**
+   * Return `true` if this function body is a generator.
+   */
+  bool get isGenerator => false;
+
+  /**
+   * Return `true` if this function body is synchronous.
+   */
+  bool get isSynchronous => true;
+
+  /**
+   * Return the token representing the 'async' or 'sync' keyword, or `null` if
+   * there is no such keyword.
+   */
+  Token get keyword => null;
+
+  /**
+   * Return the star following the 'async' or 'sync' keyword, or `null` if there
+   * is no star.
+   */
+  Token get star => null;
+}
+
+/**
+ * A top-level declaration.
+ *
+ * > functionDeclaration ::=
+ * >     'external' functionSignature
+ * >   | functionSignature [FunctionBody]
+ * >
+ * > functionSignature ::=
+ * >     [Type]? ('get' | 'set')? [SimpleIdentifier] [FormalParameterList]
+ */
+class FunctionDeclaration extends NamedCompilationUnitMember {
+  /**
+   * The token representing the 'external' keyword, or `null` if this is not an
+   * external function.
+   */
+  Token externalKeyword;
+
+  /**
+   * The return type of the function, or `null` if no return type was declared.
+   */
+  TypeName _returnType;
+
+  /**
+   * The token representing the 'get' or 'set' keyword, or `null` if this is a
+   * function declaration rather than a property declaration.
+   */
+  Token propertyKeyword;
+
+  /**
+   * The function expression being wrapped.
+   */
+  FunctionExpression _functionExpression;
+
+  /**
+   * Initialize a newly created function declaration. Either or both of the
+   * [comment] and [metadata] can be `null` if the function does not have the
+   * corresponding attribute. The [externalKeyword] can be `null` if the
+   * function is not an external function. The [returnType] can be `null` if no
+   * return type was specified. The [propertyKeyword] can be `null` if the
+   * function is neither a getter or a setter.
+   */
+  FunctionDeclaration(Comment comment, List<Annotation> metadata,
+      this.externalKeyword, TypeName returnType, this.propertyKeyword,
+      SimpleIdentifier name, FunctionExpression functionExpression)
+      : super(comment, metadata, name) {
+    _returnType = _becomeParentOf(returnType);
+    _functionExpression = _becomeParentOf(functionExpression);
+  }
+
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(externalKeyword)
+    ..add(_returnType)
+    ..add(propertyKeyword)
+    ..add(_name)
+    ..add(_functionExpression);
+
+  @override
+  ExecutableElement get element =>
+      _name != null ? (_name.staticElement as ExecutableElement) : null;
+
+  @override
+  Token get endToken => _functionExpression.endToken;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata {
+    if (externalKeyword != null) {
+      return externalKeyword;
+    } else if (_returnType != null) {
+      return _returnType.beginToken;
+    } else if (propertyKeyword != null) {
+      return propertyKeyword;
+    } else if (_name != null) {
+      return _name.beginToken;
+    }
+    return _functionExpression.beginToken;
+  }
+
+  /**
+   * Return the function expression being wrapped.
+   */
+  FunctionExpression get functionExpression => _functionExpression;
+
+  /**
+   * Set the function expression being wrapped to the given
+   * [functionExpression].
+   */
+  void set functionExpression(FunctionExpression functionExpression) {
+    _functionExpression = _becomeParentOf(functionExpression);
+  }
+
+  /**
+   * Return `true` if this function declares a getter.
+   */
+  bool get isGetter => propertyKeyword != null &&
+      (propertyKeyword as KeywordToken).keyword == Keyword.GET;
+
+  /**
+   * Return `true` if this function declares a setter.
+   */
+  bool get isSetter => propertyKeyword != null &&
+      (propertyKeyword as KeywordToken).keyword == Keyword.SET;
+
+  /**
+   * Return the return type of the function, or `null` if no return type was
+   * declared.
+   */
+  TypeName get returnType => _returnType;
+
+  /**
+   * Set the return type of the function to the given [returnType].
+   */
+  void set returnType(TypeName returnType) {
+    _returnType = _becomeParentOf(returnType);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitFunctionDeclaration(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_returnType, visitor);
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_functionExpression, visitor);
+  }
+}
+
+/**
+ * A [FunctionDeclaration] used as a statement.
+ */
+class FunctionDeclarationStatement extends Statement {
+  /**
+   * The function declaration being wrapped.
+   */
+  FunctionDeclaration _functionDeclaration;
+
+  /**
+   * Initialize a newly created function declaration statement.
+   */
+  FunctionDeclarationStatement(FunctionDeclaration functionDeclaration) {
+    _functionDeclaration = _becomeParentOf(functionDeclaration);
+  }
+
+  @override
+  Token get beginToken => _functionDeclaration.beginToken;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(_functionDeclaration);
+
+  @override
+  Token get endToken => _functionDeclaration.endToken;
+
+  /**
+   * Return the function declaration being wrapped.
+   */
+  FunctionDeclaration get functionDeclaration => _functionDeclaration;
+
+  /**
+   * Set the function declaration being wrapped to the given
+   * [functionDeclaration].
+   */
+  void set functionDeclaration(FunctionDeclaration functionDeclaration) {
+    _functionDeclaration = _becomeParentOf(functionDeclaration);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitFunctionDeclarationStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_functionDeclaration, visitor);
+  }
+}
+
+/**
+ * A function expression.
+ *
+ * > functionExpression ::=
+ * >     [TypeParameterList]? [FormalParameterList] [FunctionBody]
+ */
+class FunctionExpression extends Expression {
+  /**
+   * The type parameters associated with the method, or `null` if the method is
+   * not a generic method.
+   */
+  TypeParameterList _typeParameters;
+
+  /**
+   * The parameters associated with the function.
+   */
+  FormalParameterList _parameters;
+
+  /**
+   * The body of the function, or `null` if this is an external function.
+   */
+  FunctionBody _body;
+
+  /**
+   * The element associated with the function, or `null` if the AST structure
+   * has not been resolved.
+   */
+  ExecutableElement element;
+
+  /**
+   * Initialize a newly created function declaration.
+   */
+  FunctionExpression(TypeParameterList typeParameters,
+      FormalParameterList parameters, FunctionBody body) {
+    _typeParameters = _becomeParentOf(typeParameters);
+    _parameters = _becomeParentOf(parameters);
+    _body = _becomeParentOf(body);
+  }
+
+  @override
+  Token get beginToken {
+    if (_typeParameters != null) {
+      return _typeParameters.beginToken;
+    } else if (_parameters != null) {
+      return _parameters.beginToken;
+    } else if (_body != null) {
+      return _body.beginToken;
+    }
+    // This should never be reached because external functions must be named,
+    // hence either the body or the name should be non-null.
+    throw new IllegalStateException("Non-external functions must have a body");
+  }
+
+  /**
+   * Return the body of the function, or `null` if this is an external function.
+   */
+  FunctionBody get body => _body;
+
+  /**
+   * Set the body of the function to the given [functionBody].
+   */
+  void set body(FunctionBody functionBody) {
+    _body = _becomeParentOf(functionBody);
+  }
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_parameters)..add(_body);
+
+  @override
+  Token get endToken {
+    if (_body != null) {
+      return _body.endToken;
+    } else if (_parameters != null) {
+      return _parameters.endToken;
+    }
+    // This should never be reached because external functions must be named,
+    // hence either the body or the name should be non-null.
+    throw new IllegalStateException("Non-external functions must have a body");
+  }
+
+  /**
+   * Return the parameters associated with the function.
+   */
+  FormalParameterList get parameters => _parameters;
+
+  /**
+   * Set the parameters associated with the function to the given list of
+   * [parameters].
+   */
+  void set parameters(FormalParameterList parameters) {
+    _parameters = _becomeParentOf(parameters);
+  }
+
+  @override
+  int get precedence => 16;
+
+  /**
+   * Return the type parameters associated with this method, or `null` if this
+   * method is not a generic method.
+   */
+  TypeParameterList get typeParameters => _typeParameters;
+
+  /**
+   * Set the type parameters associated with this method to the given
+   * [typeParameters].
+   */
+  void set typeParameters(TypeParameterList typeParameters) {
+    _typeParameters = _becomeParentOf(typeParameters);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitFunctionExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_typeParameters, visitor);
+    _safelyVisitChild(_parameters, visitor);
+    _safelyVisitChild(_body, visitor);
+  }
+}
+
+/**
+ * The invocation of a function resulting from evaluating an expression.
+ * Invocations of methods and other forms of functions are represented by
+ * [MethodInvocation] nodes. Invocations of getters and setters are represented
+ * by either [PrefixedIdentifier] or [PropertyAccess] nodes.
+ *
+ * > functionExpressionInvoction ::=
+ * >     [Expression] [TypeArgumentList]? [ArgumentList]
+ */
+class FunctionExpressionInvocation extends Expression {
+  /**
+   * The expression producing the function being invoked.
+   */
+  Expression _function;
+
+  /**
+   * The type arguments to be applied to the method being invoked, or `null` if
+   * no type arguments were provided.
+   */
+  TypeArgumentList _typeArguments;
+
+  /**
+   * The list of arguments to the function.
+   */
+  ArgumentList _argumentList;
+
+  /**
+   * The element associated with the function being invoked based on static type
+   * information, or `null` if the AST structure has not been resolved or the
+   * function could not be resolved.
+   */
+  ExecutableElement staticElement;
+
+  /**
+   * The element associated with the function being invoked based on propagated
+   * type information, or `null` if the AST structure has not been resolved or
+   * the function could not be resolved.
+   */
+  ExecutableElement propagatedElement;
+
+  /**
+   * Initialize a newly created function expression invocation.
+   */
+  FunctionExpressionInvocation(Expression function,
+      TypeArgumentList typeArguments, ArgumentList argumentList) {
+    _function = _becomeParentOf(function);
+    _typeArguments = _becomeParentOf(typeArguments);
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  /**
+   * Return the list of arguments to the method.
+   */
+  ArgumentList get argumentList => _argumentList;
+
+  /**
+   * Set the list of arguments to the method to the given [argumentList].
+   */
+  void set argumentList(ArgumentList argumentList) {
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  @override
+  Token get beginToken => _function.beginToken;
+
+  /**
+   * Return the best element available for the function being invoked. If
+   * resolution was able to find a better element based on type propagation,
+   * that element will be returned. Otherwise, the element found using the
+   * result of static analysis will be returned. If resolution has not been
+   * performed, then `null` will be returned.
+   */
+  ExecutableElement get bestElement {
+    ExecutableElement element = propagatedElement;
+    if (element == null) {
+      element = staticElement;
+    }
+    return element;
+  }
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_function)..add(_argumentList);
+
+  @override
+  Token get endToken => _argumentList.endToken;
+
+  /**
+   * Return the expression producing the function being invoked.
+   */
+  Expression get function => _function;
+
+  /**
+   * Set the expression producing the function being invoked to the given
+   * [expression].
+   */
+  void set function(Expression expression) {
+    _function = _becomeParentOf(expression);
+  }
+
+  @override
+  int get precedence => 15;
+
+  /**
+   * Return the type arguments to be applied to the method being invoked, or
+   * `null` if no type arguments were provided.
+   */
+  TypeArgumentList get typeArguments => _typeArguments;
+
+  /**
+   * Set the type arguments to be applied to the method being invoked to the
+   * given [typeArguments].
+   */
+  void set typeArguments(TypeArgumentList typeArguments) {
+    _typeArguments = _becomeParentOf(typeArguments);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitFunctionExpressionInvocation(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_function, visitor);
+    _safelyVisitChild(_typeArguments, visitor);
+    _safelyVisitChild(_argumentList, visitor);
+  }
+}
+
+/**
+ * A function type alias.
+ *
+ * > functionTypeAlias ::=
+ * >     functionPrefix [TypeParameterList]? [FormalParameterList] ';'
+ * >
+ * > functionPrefix ::=
+ * >     [TypeName]? [SimpleIdentifier]
+ */
+class FunctionTypeAlias extends TypeAlias {
+  /**
+   * The name of the return type of the function type being defined, or `null`
+   * if no return type was given.
+   */
+  TypeName _returnType;
+
+  /**
+   * The type parameters for the function type, or `null` if the function type
+   * does not have any type parameters.
+   */
+  TypeParameterList _typeParameters;
+
+  /**
+   * The parameters associated with the function type.
+   */
+  FormalParameterList _parameters;
+
+  /**
+   * Initialize a newly created function type alias. Either or both of the
+   * [comment] and [metadata] can be `null` if the function does not have the
+   * corresponding attribute. The [returnType] can be `null` if no return type
+   * was specified. The [typeParameters] can be `null` if the function has no
+   * type parameters.
+   */
+  FunctionTypeAlias(Comment comment, List<Annotation> metadata, Token keyword,
+      TypeName returnType, SimpleIdentifier name,
+      TypeParameterList typeParameters, FormalParameterList parameters,
+      Token semicolon)
+      : super(comment, metadata, keyword, name, semicolon) {
+    _returnType = _becomeParentOf(returnType);
+    _typeParameters = _becomeParentOf(typeParameters);
+    _parameters = _becomeParentOf(parameters);
+  }
+
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(typedefKeyword)
+    ..add(_returnType)
+    ..add(_name)
+    ..add(_typeParameters)
+    ..add(_parameters)
+    ..add(semicolon);
+
+  @override
+  FunctionTypeAliasElement get element =>
+      _name != null ? (_name.staticElement as FunctionTypeAliasElement) : null;
+
+  /**
+   * Return the parameters associated with the function type.
+   */
+  FormalParameterList get parameters => _parameters;
+
+  /**
+   * Set the parameters associated with the function type to the given list of
+   * [parameters].
+   */
+  void set parameters(FormalParameterList parameters) {
+    _parameters = _becomeParentOf(parameters);
+  }
+
+  /**
+   * Return the name of the return type of the function type being defined, or
+   * `null` if no return type was given.
+   */
+  TypeName get returnType => _returnType;
+
+  /**
+   * Set the name of the return type of the function type being defined to the
+   * given [typeName].
+   */
+  void set returnType(TypeName typeName) {
+    _returnType = _becomeParentOf(typeName);
+  }
+
+  /**
+   * Return the type parameters for the function type, or `null` if the function
+   * type does not have any type parameters.
+   */
+  TypeParameterList get typeParameters => _typeParameters;
+
+  /**
+   * Set the type parameters for the function type to the given list of
+   * [typeParameters].
+   */
+  void set typeParameters(TypeParameterList typeParameters) {
+    _typeParameters = _becomeParentOf(typeParameters);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitFunctionTypeAlias(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_returnType, visitor);
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_typeParameters, visitor);
+    _safelyVisitChild(_parameters, visitor);
+  }
+}
+
+/**
+ * A function-typed formal parameter.
+ *
+ * > functionSignature ::=
+ * >     [TypeName]? [SimpleIdentifier] [TypeParameterList]? [FormalParameterList]
+ */
+class FunctionTypedFormalParameter extends NormalFormalParameter {
+  /**
+   * The return type of the function, or `null` if the function does not have a
+   * return type.
+   */
+  TypeName _returnType;
+
+  /**
+   * The type parameters associated with the function, or `null` if the function
+   * is not a generic function.
+   */
+  TypeParameterList _typeParameters;
+
+  /**
+   * The parameters of the function-typed parameter.
+   */
+  FormalParameterList _parameters;
+
+  /**
+   * Initialize a newly created formal parameter. Either or both of the
+   * [comment] and [metadata] can be `null` if the parameter does not have the
+   * corresponding attribute. The [returnType] can be `null` if no return type
+   * was specified.
+   */
+  FunctionTypedFormalParameter(Comment comment, List<Annotation> metadata,
+      TypeName returnType, SimpleIdentifier identifier,
+      TypeParameterList typeParameters, FormalParameterList parameters)
+      : super(comment, metadata, identifier) {
+    _returnType = _becomeParentOf(returnType);
+    _typeParameters = _becomeParentOf(typeParameters);
+    _parameters = _becomeParentOf(parameters);
+  }
+
+  @override
+  Token get beginToken {
+    if (_returnType != null) {
+      return _returnType.beginToken;
+    }
+    return identifier.beginToken;
+  }
+
+  @override
+  Iterable get childEntities =>
+      super._childEntities..add(_returnType)..add(identifier)..add(parameters);
+
+  @override
+  Token get endToken => _parameters.endToken;
+
+  @override
+  bool get isConst => false;
+
+  @override
+  bool get isFinal => false;
+
+  /**
+   * Return the parameters of the function-typed parameter.
+   */
+  FormalParameterList get parameters => _parameters;
+
+  /**
+   * Set the parameters of the function-typed parameter to the given
+   * [parameters].
+   */
+  void set parameters(FormalParameterList parameters) {
+    _parameters = _becomeParentOf(parameters);
+  }
+
+  /**
+   * Return the return type of the function, or `null` if the function does not
+   * have a return type.
+   */
+  TypeName get returnType => _returnType;
+
+  /**
+   * Set the return type of the function to the given [type].
+   */
+  void set returnType(TypeName type) {
+    _returnType = _becomeParentOf(type);
+  }
+
+  /**
+   * Return the type parameters associated with this function, or `null` if
+   * this function is not a generic function.
+   */
+  TypeParameterList get typeParameters => _typeParameters;
+
+  /**
+   * Set the type parameters associated with this method to the given
+   * [typeParameters].
+   */
+  void set typeParameters(TypeParameterList typeParameters) {
+    _typeParameters = _becomeParentOf(typeParameters);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitFunctionTypedFormalParameter(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_returnType, visitor);
+    _safelyVisitChild(identifier, visitor);
+    _safelyVisitChild(_typeParameters, visitor);
+    _safelyVisitChild(_parameters, visitor);
+  }
+}
+
+/**
+ * An AST visitor that will recursively visit all of the nodes in an AST
+ * structure (like instances of the class [RecursiveAstVisitor]). In addition,
+ * when a node of a specific type is visited not only will the visit method for
+ * that specific type of node be invoked, but additional methods for the
+ * superclasses of that node will also be invoked. For example, using an
+ * instance of this class to visit a [Block] will cause the method [visitBlock]
+ * to be invoked but will also cause the methods [visitStatement] and
+ * [visitNode] to be subsequently invoked. This allows visitors to be written
+ * that visit all statements without needing to override the visit method for
+ * each of the specific subclasses of [Statement].
+ *
+ * Subclasses that override a visit method must either invoke the overridden
+ * visit method or explicitly invoke the more general visit method. Failure to
+ * do so will cause the visit methods for superclasses of the node to not be
+ * invoked and will cause the children of the visited node to not be visited.
+ */
+class GeneralizingAstVisitor<R> implements AstVisitor<R> {
+  @override
+  R visitAdjacentStrings(AdjacentStrings node) => visitStringLiteral(node);
+
+  R visitAnnotatedNode(AnnotatedNode node) => visitNode(node);
+
+  @override
+  R visitAnnotation(Annotation node) => visitNode(node);
+
+  @override
+  R visitArgumentList(ArgumentList node) => visitNode(node);
+
+  @override
+  R visitAsExpression(AsExpression node) => visitExpression(node);
+
+  @override
+  R visitAssertStatement(AssertStatement node) => visitStatement(node);
+
+  @override
+  R visitAssignmentExpression(AssignmentExpression node) =>
+      visitExpression(node);
+
+  @override
+  R visitAwaitExpression(AwaitExpression node) => visitExpression(node);
+
+  @override
+  R visitBinaryExpression(BinaryExpression node) => visitExpression(node);
+
+  @override
+  R visitBlock(Block node) => visitStatement(node);
+
+  @override
+  R visitBlockFunctionBody(BlockFunctionBody node) => visitFunctionBody(node);
+
+  @override
+  R visitBooleanLiteral(BooleanLiteral node) => visitLiteral(node);
+
+  @override
+  R visitBreakStatement(BreakStatement node) => visitStatement(node);
+
+  @override
+  R visitCascadeExpression(CascadeExpression node) => visitExpression(node);
+
+  @override
+  R visitCatchClause(CatchClause node) => visitNode(node);
+
+  @override
+  R visitClassDeclaration(ClassDeclaration node) =>
+      visitNamedCompilationUnitMember(node);
+
+  R visitClassMember(ClassMember node) => visitDeclaration(node);
+
+  @override
+  R visitClassTypeAlias(ClassTypeAlias node) => visitTypeAlias(node);
+
+  R visitCombinator(Combinator node) => visitNode(node);
+
+  @override
+  R visitComment(Comment node) => visitNode(node);
+
+  @override
+  R visitCommentReference(CommentReference node) => visitNode(node);
+
+  @override
+  R visitCompilationUnit(CompilationUnit node) => visitNode(node);
+
+  R visitCompilationUnitMember(CompilationUnitMember node) =>
+      visitDeclaration(node);
+
+  @override
+  R visitConditionalExpression(ConditionalExpression node) =>
+      visitExpression(node);
+
+  @override
+  R visitConstructorDeclaration(ConstructorDeclaration node) =>
+      visitClassMember(node);
+
+  @override
+  R visitConstructorFieldInitializer(ConstructorFieldInitializer node) =>
+      visitConstructorInitializer(node);
+
+  R visitConstructorInitializer(ConstructorInitializer node) => visitNode(node);
+
+  @override
+  R visitConstructorName(ConstructorName node) => visitNode(node);
+
+  @override
+  R visitContinueStatement(ContinueStatement node) => visitStatement(node);
+
+  R visitDeclaration(Declaration node) => visitAnnotatedNode(node);
+
+  @override
+  R visitDeclaredIdentifier(DeclaredIdentifier node) => visitDeclaration(node);
+
+  @override
+  R visitDefaultFormalParameter(DefaultFormalParameter node) =>
+      visitFormalParameter(node);
+
+  R visitDirective(Directive node) => visitAnnotatedNode(node);
+
+  @override
+  R visitDoStatement(DoStatement node) => visitStatement(node);
+
+  @override
+  R visitDoubleLiteral(DoubleLiteral node) => visitLiteral(node);
+
+  @override
+  R visitEmptyFunctionBody(EmptyFunctionBody node) => visitFunctionBody(node);
+
+  @override
+  R visitEmptyStatement(EmptyStatement node) => visitStatement(node);
+
+  @override
+  R visitEnumConstantDeclaration(EnumConstantDeclaration node) =>
+      visitDeclaration(node);
+
+  @override
+  R visitEnumDeclaration(EnumDeclaration node) =>
+      visitNamedCompilationUnitMember(node);
+
+  @override
+  R visitExportDirective(ExportDirective node) => visitNamespaceDirective(node);
+
+  R visitExpression(Expression node) => visitNode(node);
+
+  @override
+  R visitExpressionFunctionBody(ExpressionFunctionBody node) =>
+      visitFunctionBody(node);
+
+  @override
+  R visitExpressionStatement(ExpressionStatement node) => visitStatement(node);
+
+  @override
+  R visitExtendsClause(ExtendsClause node) => visitNode(node);
+
+  @override
+  R visitFieldDeclaration(FieldDeclaration node) => visitClassMember(node);
+
+  @override
+  R visitFieldFormalParameter(FieldFormalParameter node) =>
+      visitNormalFormalParameter(node);
+
+  @override
+  R visitForEachStatement(ForEachStatement node) => visitStatement(node);
+
+  R visitFormalParameter(FormalParameter node) => visitNode(node);
+
+  @override
+  R visitFormalParameterList(FormalParameterList node) => visitNode(node);
+
+  @override
+  R visitForStatement(ForStatement node) => visitStatement(node);
+
+  R visitFunctionBody(FunctionBody node) => visitNode(node);
+
+  @override
+  R visitFunctionDeclaration(FunctionDeclaration node) =>
+      visitNamedCompilationUnitMember(node);
+
+  @override
+  R visitFunctionDeclarationStatement(FunctionDeclarationStatement node) =>
+      visitStatement(node);
+
+  @override
+  R visitFunctionExpression(FunctionExpression node) => visitExpression(node);
+
+  @override
+  R visitFunctionExpressionInvocation(FunctionExpressionInvocation node) =>
+      visitExpression(node);
+
+  @override
+  R visitFunctionTypeAlias(FunctionTypeAlias node) => visitTypeAlias(node);
+
+  @override
+  R visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) =>
+      visitNormalFormalParameter(node);
+
+  @override
+  R visitHideCombinator(HideCombinator node) => visitCombinator(node);
+
+  R visitIdentifier(Identifier node) => visitExpression(node);
+
+  @override
+  R visitIfStatement(IfStatement node) => visitStatement(node);
+
+  @override
+  R visitImplementsClause(ImplementsClause node) => visitNode(node);
+
+  @override
+  R visitImportDirective(ImportDirective node) => visitNamespaceDirective(node);
+
+  @override
+  R visitIndexExpression(IndexExpression node) => visitExpression(node);
+
+  @override
+  R visitInstanceCreationExpression(InstanceCreationExpression node) =>
+      visitExpression(node);
+
+  @override
+  R visitIntegerLiteral(IntegerLiteral node) => visitLiteral(node);
+
+  R visitInterpolationElement(InterpolationElement node) => visitNode(node);
+
+  @override
+  R visitInterpolationExpression(InterpolationExpression node) =>
+      visitInterpolationElement(node);
+
+  @override
+  R visitInterpolationString(InterpolationString node) =>
+      visitInterpolationElement(node);
+
+  @override
+  R visitIsExpression(IsExpression node) => visitExpression(node);
+
+  @override
+  R visitLabel(Label node) => visitNode(node);
+
+  @override
+  R visitLabeledStatement(LabeledStatement node) => visitStatement(node);
+
+  @override
+  R visitLibraryDirective(LibraryDirective node) => visitDirective(node);
+
+  @override
+  R visitLibraryIdentifier(LibraryIdentifier node) => visitIdentifier(node);
+
+  @override
+  R visitListLiteral(ListLiteral node) => visitTypedLiteral(node);
+
+  R visitLiteral(Literal node) => visitExpression(node);
+
+  @override
+  R visitMapLiteral(MapLiteral node) => visitTypedLiteral(node);
+
+  @override
+  R visitMapLiteralEntry(MapLiteralEntry node) => visitNode(node);
+
+  @override
+  R visitMethodDeclaration(MethodDeclaration node) => visitClassMember(node);
+
+  @override
+  R visitMethodInvocation(MethodInvocation node) => visitExpression(node);
+
+  R visitNamedCompilationUnitMember(NamedCompilationUnitMember node) =>
+      visitCompilationUnitMember(node);
+
+  @override
+  R visitNamedExpression(NamedExpression node) => visitExpression(node);
+
+  R visitNamespaceDirective(NamespaceDirective node) =>
+      visitUriBasedDirective(node);
+
+  @override
+  R visitNativeClause(NativeClause node) => visitNode(node);
+
+  @override
+  R visitNativeFunctionBody(NativeFunctionBody node) => visitFunctionBody(node);
+
+  R visitNode(AstNode node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  R visitNormalFormalParameter(NormalFormalParameter node) =>
+      visitFormalParameter(node);
+
+  @override
+  R visitNullLiteral(NullLiteral node) => visitLiteral(node);
+
+  @override
+  R visitParenthesizedExpression(ParenthesizedExpression node) =>
+      visitExpression(node);
+
+  @override
+  R visitPartDirective(PartDirective node) => visitUriBasedDirective(node);
+
+  @override
+  R visitPartOfDirective(PartOfDirective node) => visitDirective(node);
+
+  @override
+  R visitPostfixExpression(PostfixExpression node) => visitExpression(node);
+
+  @override
+  R visitPrefixedIdentifier(PrefixedIdentifier node) => visitIdentifier(node);
+
+  @override
+  R visitPrefixExpression(PrefixExpression node) => visitExpression(node);
+
+  @override
+  R visitPropertyAccess(PropertyAccess node) => visitExpression(node);
+
+  @override
+  R visitRedirectingConstructorInvocation(
+          RedirectingConstructorInvocation node) =>
+      visitConstructorInitializer(node);
+
+  @override
+  R visitRethrowExpression(RethrowExpression node) => visitExpression(node);
+
+  @override
+  R visitReturnStatement(ReturnStatement node) => visitStatement(node);
+
+  @override
+  R visitScriptTag(ScriptTag scriptTag) => visitNode(scriptTag);
+
+  @override
+  R visitShowCombinator(ShowCombinator node) => visitCombinator(node);
+
+  @override
+  R visitSimpleFormalParameter(SimpleFormalParameter node) =>
+      visitNormalFormalParameter(node);
+
+  @override
+  R visitSimpleIdentifier(SimpleIdentifier node) => visitIdentifier(node);
+
+  @override
+  R visitSimpleStringLiteral(SimpleStringLiteral node) =>
+      visitSingleStringLiteral(node);
+
+  R visitSingleStringLiteral(SingleStringLiteral node) =>
+      visitStringLiteral(node);
+
+  R visitStatement(Statement node) => visitNode(node);
+
+  @override
+  R visitStringInterpolation(StringInterpolation node) =>
+      visitSingleStringLiteral(node);
+
+  R visitStringLiteral(StringLiteral node) => visitLiteral(node);
+
+  @override
+  R visitSuperConstructorInvocation(SuperConstructorInvocation node) =>
+      visitConstructorInitializer(node);
+
+  @override
+  R visitSuperExpression(SuperExpression node) => visitExpression(node);
+
+  @override
+  R visitSwitchCase(SwitchCase node) => visitSwitchMember(node);
+
+  @override
+  R visitSwitchDefault(SwitchDefault node) => visitSwitchMember(node);
+
+  R visitSwitchMember(SwitchMember node) => visitNode(node);
+
+  @override
+  R visitSwitchStatement(SwitchStatement node) => visitStatement(node);
+
+  @override
+  R visitSymbolLiteral(SymbolLiteral node) => visitLiteral(node);
+
+  @override
+  R visitThisExpression(ThisExpression node) => visitExpression(node);
+
+  @override
+  R visitThrowExpression(ThrowExpression node) => visitExpression(node);
+
+  @override
+  R visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) =>
+      visitCompilationUnitMember(node);
+
+  @override
+  R visitTryStatement(TryStatement node) => visitStatement(node);
+
+  R visitTypeAlias(TypeAlias node) => visitNamedCompilationUnitMember(node);
+
+  @override
+  R visitTypeArgumentList(TypeArgumentList node) => visitNode(node);
+
+  R visitTypedLiteral(TypedLiteral node) => visitLiteral(node);
+
+  @override
+  R visitTypeName(TypeName node) => visitNode(node);
+
+  @override
+  R visitTypeParameter(TypeParameter node) => visitNode(node);
+
+  @override
+  R visitTypeParameterList(TypeParameterList node) => visitNode(node);
+
+  R visitUriBasedDirective(UriBasedDirective node) => visitDirective(node);
+
+  @override
+  R visitVariableDeclaration(VariableDeclaration node) =>
+      visitDeclaration(node);
+
+  @override
+  R visitVariableDeclarationList(VariableDeclarationList node) =>
+      visitNode(node);
+
+  @override
+  R visitVariableDeclarationStatement(VariableDeclarationStatement node) =>
+      visitStatement(node);
+
+  @override
+  R visitWhileStatement(WhileStatement node) => visitStatement(node);
+
+  @override
+  R visitWithClause(WithClause node) => visitNode(node);
+
+  @override
+  R visitYieldStatement(YieldStatement node) => visitStatement(node);
+}
+
+class GeneralizingAstVisitor_BreadthFirstVisitor
+    extends GeneralizingAstVisitor<Object> {
+  final BreadthFirstVisitor BreadthFirstVisitor_this;
+
+  GeneralizingAstVisitor_BreadthFirstVisitor(this.BreadthFirstVisitor_this)
+      : super();
+
+  @override
+  Object visitNode(AstNode node) {
+    BreadthFirstVisitor_this._queue.add(node);
+    return null;
+  }
+}
+
+/**
+ * A combinator that restricts the names being imported to those that are not in
+ * a given list.
+ *
+ * > hideCombinator ::=
+ * >     'hide' [SimpleIdentifier] (',' [SimpleIdentifier])*
+ */
+class HideCombinator extends Combinator {
+  /**
+   * The list of names from the library that are hidden by this combinator.
+   */
+  NodeList<SimpleIdentifier> _hiddenNames;
+
+  /**
+   * Initialize a newly created import show combinator.
+   */
+  HideCombinator(Token keyword, List<SimpleIdentifier> hiddenNames)
+      : super(keyword) {
+    _hiddenNames = new NodeList<SimpleIdentifier>(this, hiddenNames);
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(keyword)
+    ..addAll(_hiddenNames);
+
+  @override
+  Token get endToken => _hiddenNames.endToken;
+
+  /**
+   * Return the list of names from the library that are hidden by this
+   * combinator.
+   */
+  NodeList<SimpleIdentifier> get hiddenNames => _hiddenNames;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitHideCombinator(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _hiddenNames.accept(visitor);
+  }
+}
+
+/**
+ * A node that represents an identifier.
+ *
+ * > identifier ::=
+ * >     [SimpleIdentifier]
+ * >   | [PrefixedIdentifier]
+ */
+abstract class Identifier extends Expression {
+  /**
+   * Return the best element available for this operator. If resolution was able
+   * to find a better element based on type propagation, that element will be
+   * returned. Otherwise, the element found using the result of static analysis
+   * will be returned. If resolution has not been performed, then `null` will be
+   * returned.
+   */
+  Element get bestElement;
+
+  @override
+  bool get isAssignable => true;
+
+  /**
+   * Return the lexical representation of the identifier.
+   */
+  String get name;
+
+  /**
+   * Return the element associated with this identifier based on propagated type
+   * information, or `null` if the AST structure has not been resolved or if
+   * this identifier could not be resolved. One example of the latter case is an
+   * identifier that is not defined within the scope in which it appears.
+   */
+  Element get propagatedElement;
+
+  /**
+   * Return the element associated with this identifier based on static type
+   * information, or `null` if the AST structure has not been resolved or if
+   * this identifier could not be resolved. One example of the latter case is an
+   * identifier that is not defined within the scope in which it appears
+   */
+  Element get staticElement;
+
+  /**
+   * Return `true` if the given [name] is visible only within the library in
+   * which it is declared.
+   */
+  static bool isPrivateName(String name) =>
+      StringUtilities.startsWithChar(name, 0x5F);
+}
+
+/**
+ * An if statement.
+ *
+ * > ifStatement ::=
+ * >     'if' '(' [Expression] ')' [Statement] ('else' [Statement])?
+ */
+class IfStatement extends Statement {
+  /**
+   * The token representing the 'if' keyword.
+   */
+  Token ifKeyword;
+
+  /**
+   * The left parenthesis.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The condition used to determine which of the statements is executed next.
+   */
+  Expression _condition;
+
+  /**
+   * The right parenthesis.
+   */
+  Token rightParenthesis;
+
+  /**
+   * The statement that is executed if the condition evaluates to `true`.
+   */
+  Statement _thenStatement;
+
+  /**
+   * The token representing the 'else' keyword, or `null` if there is no else
+   * statement.
+   */
+  Token elseKeyword;
+
+  /**
+   * The statement that is executed if the condition evaluates to `false`, or
+   * `null` if there is no else statement.
+   */
+  Statement _elseStatement;
+
+  /**
+   * Initialize a newly created if statement. The [elseKeyword] and
+   * [elseStatement] can be `null` if there is no else clause.
+   */
+  IfStatement(this.ifKeyword, this.leftParenthesis, Expression condition,
+      this.rightParenthesis, Statement thenStatement, this.elseKeyword,
+      Statement elseStatement) {
+    _condition = _becomeParentOf(condition);
+    _thenStatement = _becomeParentOf(thenStatement);
+    _elseStatement = _becomeParentOf(elseStatement);
+  }
+
+  @override
+  Token get beginToken => ifKeyword;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(ifKeyword)
+    ..add(leftParenthesis)
+    ..add(_condition)
+    ..add(rightParenthesis)
+    ..add(_thenStatement)
+    ..add(elseKeyword)
+    ..add(_elseStatement);
+
+  /**
+   * Return the condition used to determine which of the statements is executed
+   * next.
+   */
+  Expression get condition => _condition;
+
+  /**
+   * Set the condition used to determine which of the statements is executed
+   * next to the given [expression].
+   */
+  void set condition(Expression expression) {
+    _condition = _becomeParentOf(expression);
+  }
+
+  /**
+   * Return the statement that is executed if the condition evaluates to
+   * `false`, or `null` if there is no else statement.
+   */
+  Statement get elseStatement => _elseStatement;
+
+  /**
+   * Set the statement that is executed if the condition evaluates to `false`
+   * to the given [statement].
+   */
+  void set elseStatement(Statement statement) {
+    _elseStatement = _becomeParentOf(statement);
+  }
+
+  @override
+  Token get endToken {
+    if (_elseStatement != null) {
+      return _elseStatement.endToken;
+    }
+    return _thenStatement.endToken;
+  }
+
+  /**
+   * Return the statement that is executed if the condition evaluates to `true`.
+   */
+  Statement get thenStatement => _thenStatement;
+
+  /**
+   * Set the statement that is executed if the condition evaluates to `true` to
+   * the given [statement].
+   */
+  void set thenStatement(Statement statement) {
+    _thenStatement = _becomeParentOf(statement);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitIfStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_condition, visitor);
+    _safelyVisitChild(_thenStatement, visitor);
+    _safelyVisitChild(_elseStatement, visitor);
+  }
+}
+
+/**
+ * The "implements" clause in an class declaration.
+ *
+ * > implementsClause ::=
+ * >     'implements' [TypeName] (',' [TypeName])*
+ */
+class ImplementsClause extends AstNode {
+  /**
+   * The token representing the 'implements' keyword.
+   */
+  Token implementsKeyword;
+
+  /**
+   * The interfaces that are being implemented.
+   */
+  NodeList<TypeName> _interfaces;
+
+  /**
+   * Initialize a newly created implements clause.
+   */
+  ImplementsClause(this.implementsKeyword, List<TypeName> interfaces) {
+    _interfaces = new NodeList<TypeName>(this, interfaces);
+  }
+
+  @override
+  Token get beginToken => implementsKeyword;
+
+  /**
+   * TODO(paulberry): add commas.
+   */
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(implementsKeyword)
+    ..addAll(interfaces);
+
+  @override
+  Token get endToken => _interfaces.endToken;
+
+  /**
+   * Return the list of the interfaces that are being implemented.
+   */
+  NodeList<TypeName> get interfaces => _interfaces;
+
+  /**
+   * Return the token representing the 'implements' keyword.
+   */
+  @deprecated // Use "this.implementsKeyword"
+  Token get keyword => implementsKeyword;
+
+  /**
+   * Set the token representing the 'implements' keyword to the given [token].
+   */
+  @deprecated // Use "this.implementsKeyword"
+  set keyword(Token token) {
+    implementsKeyword = token;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitImplementsClause(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _interfaces.accept(visitor);
+  }
+}
+
+/**
+ * An import directive.
+ *
+ * > importDirective ::=
+ * >     [Annotation] 'import' [StringLiteral] ('as' identifier)? [Combinator]* ';'
+ * >   | [Annotation] 'import' [StringLiteral] 'deferred' 'as' identifier [Combinator]* ';'
+ */
+class ImportDirective extends NamespaceDirective {
+  static Comparator<ImportDirective> COMPARATOR = (ImportDirective import1,
+      ImportDirective import2) {
+    //
+    // uri
+    //
+    StringLiteral uri1 = import1.uri;
+    StringLiteral uri2 = import2.uri;
+    String uriStr1 = uri1.stringValue;
+    String uriStr2 = uri2.stringValue;
+    if (uriStr1 != null || uriStr2 != null) {
+      if (uriStr1 == null) {
+        return -1;
+      } else if (uriStr2 == null) {
+        return 1;
+      } else {
+        int compare = uriStr1.compareTo(uriStr2);
+        if (compare != 0) {
+          return compare;
+        }
+      }
+    }
+    //
+    // as
+    //
+    SimpleIdentifier prefix1 = import1.prefix;
+    SimpleIdentifier prefix2 = import2.prefix;
+    String prefixStr1 = prefix1 != null ? prefix1.name : null;
+    String prefixStr2 = prefix2 != null ? prefix2.name : null;
+    if (prefixStr1 != null || prefixStr2 != null) {
+      if (prefixStr1 == null) {
+        return -1;
+      } else if (prefixStr2 == null) {
+        return 1;
+      } else {
+        int compare = prefixStr1.compareTo(prefixStr2);
+        if (compare != 0) {
+          return compare;
+        }
+      }
+    }
+    //
+    // hides and shows
+    //
+    NodeList<Combinator> combinators1 = import1.combinators;
+    List<String> allHides1 = new List<String>();
+    List<String> allShows1 = new List<String>();
+    for (Combinator combinator in combinators1) {
+      if (combinator is HideCombinator) {
+        NodeList<SimpleIdentifier> hides = combinator.hiddenNames;
+        for (SimpleIdentifier simpleIdentifier in hides) {
+          allHides1.add(simpleIdentifier.name);
+        }
+      } else {
+        NodeList<SimpleIdentifier> shows =
+            (combinator as ShowCombinator).shownNames;
+        for (SimpleIdentifier simpleIdentifier in shows) {
+          allShows1.add(simpleIdentifier.name);
+        }
+      }
+    }
+    NodeList<Combinator> combinators2 = import2.combinators;
+    List<String> allHides2 = new List<String>();
+    List<String> allShows2 = new List<String>();
+    for (Combinator combinator in combinators2) {
+      if (combinator is HideCombinator) {
+        NodeList<SimpleIdentifier> hides = combinator.hiddenNames;
+        for (SimpleIdentifier simpleIdentifier in hides) {
+          allHides2.add(simpleIdentifier.name);
+        }
+      } else {
+        NodeList<SimpleIdentifier> shows =
+            (combinator as ShowCombinator).shownNames;
+        for (SimpleIdentifier simpleIdentifier in shows) {
+          allShows2.add(simpleIdentifier.name);
+        }
+      }
+    }
+    // test lengths of combinator lists first
+    if (allHides1.length != allHides2.length) {
+      return allHides1.length - allHides2.length;
+    }
+    if (allShows1.length != allShows2.length) {
+      return allShows1.length - allShows2.length;
+    }
+    // next ensure that the lists are equivalent
+    if (!javaCollectionContainsAll(allHides1, allHides2)) {
+      return -1;
+    }
+    if (!javaCollectionContainsAll(allShows1, allShows2)) {
+      return -1;
+    }
+    return 0;
+  };
+
+  /**
+   * The token representing the 'deferred' keyword, or `null` if the imported is
+   * not deferred.
+   */
+  Token deferredKeyword;
+
+  /**
+   * The token representing the 'as' keyword, or `null` if the imported names are
+   * not prefixed.
+   */
+  Token asKeyword;
+
+  /**
+   * The prefix to be used with the imported names, or `null` if the imported
+   * names are not prefixed.
+   */
+  SimpleIdentifier _prefix;
+
+  /**
+   * Initialize a newly created import directive. Either or both of the
+   * [comment] and [metadata] can be `null` if the function does not have the
+   * corresponding attribute. The [deferredKeyword] can be `null` if the import
+   * is not deferred. The [asKeyword] and [prefix] can be `null` if the import
+   * does not specify a prefix. The list of [combinators] can be `null` if there
+   * are no combinators.
+   */
+  ImportDirective(Comment comment, List<Annotation> metadata, Token keyword,
+      StringLiteral libraryUri, this.deferredKeyword, this.asKeyword,
+      SimpleIdentifier prefix, List<Combinator> combinators, Token semicolon)
+      : super(comment, metadata, keyword, libraryUri, combinators, semicolon) {
+    _prefix = _becomeParentOf(prefix);
+  }
+
+  /**
+   * The token representing the 'as' token, or `null` if the imported names are
+   * not prefixed.
+   */
+  @deprecated // Use "this.asKeyword"
+  Token get asToken => asKeyword;
+
+  /**
+   * The token representing the 'as' token to the given token.
+   */
+  @deprecated // Use "this.asKeyword"
+  set asToken(Token token) {
+    asKeyword = token;
+  }
+
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(_uri)
+    ..add(deferredKeyword)
+    ..add(asKeyword)
+    ..add(_prefix)
+    ..addAll(combinators)
+    ..add(semicolon);
+
+  /**
+   * Return the token representing the 'deferred' token, or `null` if the
+   * imported is not deferred.
+   */
+  @deprecated // Use "this.deferredKeyword"
+  Token get deferredToken => deferredKeyword;
+
+  /**
+   * Set the token representing the 'deferred' token to the given token.
+   */
+  @deprecated // Use "this.deferredKeyword"
+  set deferredToken(Token token) {
+    deferredKeyword = token;
+  }
+
+  @override
+  ImportElement get element => super.element as ImportElement;
+
+  /**
+   * Return the prefix to be used with the imported names, or `null` if the
+   * imported names are not prefixed.
+   */
+  SimpleIdentifier get prefix => _prefix;
+
+  /**
+   * Set the prefix to be used with the imported names to the given [identifier].
+   */
+  void set prefix(SimpleIdentifier identifier) {
+    _prefix = _becomeParentOf(identifier);
+  }
+
+  @override
+  LibraryElement get uriElement {
+    ImportElement element = this.element;
+    if (element == null) {
+      return null;
+    }
+    return element.importedLibrary;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitImportDirective(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_prefix, visitor);
+    combinators.accept(visitor);
+  }
+}
+
+/**
+ * An object that will clone any AST structure that it visits. The cloner will
+ * clone the structure, replacing the specified ASTNode with a new ASTNode,
+ * mapping the old token stream to a new token stream, and preserving resolution
+ * results.
+ */
+class IncrementalAstCloner implements AstVisitor<AstNode> {
+  /**
+   * The node to be replaced during the cloning process.
+   */
+  final AstNode _oldNode;
+
+  /**
+   * The replacement node used during the cloning process.
+   */
+  final AstNode _newNode;
+
+  /**
+   * A mapping of old tokens to new tokens used during the cloning process.
+   */
+  final TokenMap _tokenMap;
+
+  /**
+   * Construct a new instance that will replace the [oldNode] with the [newNode]
+   * in the process of cloning an existing AST structure. The [tokenMap] is a
+   * mapping of old tokens to new tokens.
+   */
+  IncrementalAstCloner(this._oldNode, this._newNode, this._tokenMap);
+
+  @override
+  AdjacentStrings visitAdjacentStrings(AdjacentStrings node) =>
+      new AdjacentStrings(_cloneNodeList(node.strings));
+
+  @override
+  Annotation visitAnnotation(Annotation node) {
+    Annotation copy = new Annotation(_mapToken(node.atSign),
+        _cloneNode(node.name), _mapToken(node.period),
+        _cloneNode(node.constructorName), _cloneNode(node.arguments));
+    copy.element = node.element;
+    return copy;
+  }
+
+  @override
+  ArgumentList visitArgumentList(ArgumentList node) => new ArgumentList(
+      _mapToken(node.leftParenthesis), _cloneNodeList(node.arguments),
+      _mapToken(node.rightParenthesis));
+
+  @override
+  AsExpression visitAsExpression(AsExpression node) {
+    AsExpression copy = new AsExpression(_cloneNode(node.expression),
+        _mapToken(node.asOperator), _cloneNode(node.type));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  AstNode visitAssertStatement(AssertStatement node) => new AssertStatement(
+      _mapToken(node.assertKeyword), _mapToken(node.leftParenthesis),
+      _cloneNode(node.condition), _mapToken(node.rightParenthesis),
+      _mapToken(node.semicolon));
+
+  @override
+  AssignmentExpression visitAssignmentExpression(AssignmentExpression node) {
+    AssignmentExpression copy = new AssignmentExpression(
+        _cloneNode(node.leftHandSide), _mapToken(node.operator),
+        _cloneNode(node.rightHandSide));
+    copy.propagatedElement = node.propagatedElement;
+    copy.propagatedType = node.propagatedType;
+    copy.staticElement = node.staticElement;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  AwaitExpression visitAwaitExpression(AwaitExpression node) =>
+      new AwaitExpression(
+          _mapToken(node.awaitKeyword), _cloneNode(node.expression));
+
+  @override
+  BinaryExpression visitBinaryExpression(BinaryExpression node) {
+    BinaryExpression copy = new BinaryExpression(_cloneNode(node.leftOperand),
+        _mapToken(node.operator), _cloneNode(node.rightOperand));
+    copy.propagatedElement = node.propagatedElement;
+    copy.propagatedType = node.propagatedType;
+    copy.staticElement = node.staticElement;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  Block visitBlock(Block node) => new Block(_mapToken(node.leftBracket),
+      _cloneNodeList(node.statements), _mapToken(node.rightBracket));
+
+  @override
+  BlockFunctionBody visitBlockFunctionBody(
+      BlockFunctionBody node) => new BlockFunctionBody(
+      _mapToken(node.keyword), _mapToken(node.star), _cloneNode(node.block));
+
+  @override
+  BooleanLiteral visitBooleanLiteral(BooleanLiteral node) {
+    BooleanLiteral copy =
+        new BooleanLiteral(_mapToken(node.literal), node.value);
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  BreakStatement visitBreakStatement(BreakStatement node) => new BreakStatement(
+      _mapToken(node.breakKeyword), _cloneNode(node.label),
+      _mapToken(node.semicolon));
+
+  @override
+  CascadeExpression visitCascadeExpression(CascadeExpression node) {
+    CascadeExpression copy = new CascadeExpression(
+        _cloneNode(node.target), _cloneNodeList(node.cascadeSections));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  CatchClause visitCatchClause(CatchClause node) => new CatchClause(
+      _mapToken(node.onKeyword), _cloneNode(node.exceptionType),
+      _mapToken(node.catchKeyword), _mapToken(node.leftParenthesis),
+      _cloneNode(node.exceptionParameter), _mapToken(node.comma),
+      _cloneNode(node.stackTraceParameter), _mapToken(node.rightParenthesis),
+      _cloneNode(node.body));
+
+  @override
+  ClassDeclaration visitClassDeclaration(ClassDeclaration node) {
+    ClassDeclaration copy = new ClassDeclaration(
+        _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+        _mapToken(node.abstractKeyword), _mapToken(node.classKeyword),
+        _cloneNode(node.name), _cloneNode(node.typeParameters),
+        _cloneNode(node.extendsClause), _cloneNode(node.withClause),
+        _cloneNode(node.implementsClause), _mapToken(node.leftBracket),
+        _cloneNodeList(node.members), _mapToken(node.rightBracket));
+    copy.nativeClause = _cloneNode(node.nativeClause);
+    return copy;
+  }
+
+  @override
+  ClassTypeAlias visitClassTypeAlias(ClassTypeAlias node) => new ClassTypeAlias(
+      _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+      _mapToken(node.typedefKeyword), _cloneNode(node.name),
+      _cloneNode(node.typeParameters), _mapToken(node.equals),
+      _mapToken(node.abstractKeyword), _cloneNode(node.superclass),
+      _cloneNode(node.withClause), _cloneNode(node.implementsClause),
+      _mapToken(node.semicolon));
+
+  @override
+  Comment visitComment(Comment node) {
+    if (node.isDocumentation) {
+      return Comment.createDocumentationCommentWithReferences(
+          _mapTokens(node.tokens), _cloneNodeList(node.references));
+    } else if (node.isBlock) {
+      return Comment.createBlockComment(_mapTokens(node.tokens));
+    }
+    return Comment.createEndOfLineComment(_mapTokens(node.tokens));
+  }
+
+  @override
+  CommentReference visitCommentReference(CommentReference node) =>
+      new CommentReference(
+          _mapToken(node.newKeyword), _cloneNode(node.identifier));
+
+  @override
+  CompilationUnit visitCompilationUnit(CompilationUnit node) {
+    CompilationUnit copy = new CompilationUnit(_mapToken(node.beginToken),
+        _cloneNode(node.scriptTag), _cloneNodeList(node.directives),
+        _cloneNodeList(node.declarations), _mapToken(node.endToken));
+    copy.lineInfo = node.lineInfo;
+    copy.element = node.element;
+    return copy;
+  }
+
+  @override
+  ConditionalExpression visitConditionalExpression(ConditionalExpression node) {
+    ConditionalExpression copy = new ConditionalExpression(
+        _cloneNode(node.condition), _mapToken(node.question),
+        _cloneNode(node.thenExpression), _mapToken(node.colon),
+        _cloneNode(node.elseExpression));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  ConstructorDeclaration visitConstructorDeclaration(
+      ConstructorDeclaration node) {
+    ConstructorDeclaration copy = new ConstructorDeclaration(
+        _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+        _mapToken(node.externalKeyword), _mapToken(node.constKeyword),
+        _mapToken(node.factoryKeyword), _cloneNode(node.returnType),
+        _mapToken(node.period), _cloneNode(node.name),
+        _cloneNode(node.parameters), _mapToken(node.separator),
+        _cloneNodeList(node.initializers),
+        _cloneNode(node.redirectedConstructor), _cloneNode(node.body));
+    copy.element = node.element;
+    return copy;
+  }
+
+  @override
+  ConstructorFieldInitializer visitConstructorFieldInitializer(
+      ConstructorFieldInitializer node) => new ConstructorFieldInitializer(
+      _mapToken(node.thisKeyword), _mapToken(node.period),
+      _cloneNode(node.fieldName), _mapToken(node.equals),
+      _cloneNode(node.expression));
+
+  @override
+  ConstructorName visitConstructorName(ConstructorName node) {
+    ConstructorName copy = new ConstructorName(
+        _cloneNode(node.type), _mapToken(node.period), _cloneNode(node.name));
+    copy.staticElement = node.staticElement;
+    return copy;
+  }
+
+  @override
+  ContinueStatement visitContinueStatement(ContinueStatement node) =>
+      new ContinueStatement(_mapToken(node.continueKeyword),
+          _cloneNode(node.label), _mapToken(node.semicolon));
+
+  @override
+  DeclaredIdentifier visitDeclaredIdentifier(DeclaredIdentifier node) =>
+      new DeclaredIdentifier(_cloneNode(node.documentationComment),
+          _cloneNodeList(node.metadata), _mapToken(node.keyword),
+          _cloneNode(node.type), _cloneNode(node.identifier));
+
+  @override
+  DefaultFormalParameter visitDefaultFormalParameter(
+      DefaultFormalParameter node) => new DefaultFormalParameter(
+      _cloneNode(node.parameter), node.kind, _mapToken(node.separator),
+      _cloneNode(node.defaultValue));
+
+  @override
+  DoStatement visitDoStatement(DoStatement node) => new DoStatement(
+      _mapToken(node.doKeyword), _cloneNode(node.body),
+      _mapToken(node.whileKeyword), _mapToken(node.leftParenthesis),
+      _cloneNode(node.condition), _mapToken(node.rightParenthesis),
+      _mapToken(node.semicolon));
+
+  @override
+  DoubleLiteral visitDoubleLiteral(DoubleLiteral node) {
+    DoubleLiteral copy = new DoubleLiteral(_mapToken(node.literal), node.value);
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  EmptyFunctionBody visitEmptyFunctionBody(EmptyFunctionBody node) =>
+      new EmptyFunctionBody(_mapToken(node.semicolon));
+
+  @override
+  EmptyStatement visitEmptyStatement(EmptyStatement node) =>
+      new EmptyStatement(_mapToken(node.semicolon));
+
+  @override
+  AstNode visitEnumConstantDeclaration(EnumConstantDeclaration node) =>
+      new EnumConstantDeclaration(_cloneNode(node.documentationComment),
+          _cloneNodeList(node.metadata), _cloneNode(node.name));
+
+  @override
+  AstNode visitEnumDeclaration(EnumDeclaration node) => new EnumDeclaration(
+      _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+      _mapToken(node.enumKeyword), _cloneNode(node.name),
+      _mapToken(node.leftBracket), _cloneNodeList(node.constants),
+      _mapToken(node.rightBracket));
+
+  @override
+  ExportDirective visitExportDirective(ExportDirective node) {
+    ExportDirective copy = new ExportDirective(
+        _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+        _mapToken(node.keyword), _cloneNode(node.uri),
+        _cloneNodeList(node.combinators), _mapToken(node.semicolon));
+    copy.element = node.element;
+    return copy;
+  }
+
+  @override
+  ExpressionFunctionBody visitExpressionFunctionBody(
+      ExpressionFunctionBody node) => new ExpressionFunctionBody(
+      _mapToken(node.keyword), _mapToken(node.functionDefinition),
+      _cloneNode(node.expression), _mapToken(node.semicolon));
+
+  @override
+  ExpressionStatement visitExpressionStatement(ExpressionStatement node) =>
+      new ExpressionStatement(
+          _cloneNode(node.expression), _mapToken(node.semicolon));
+
+  @override
+  ExtendsClause visitExtendsClause(ExtendsClause node) => new ExtendsClause(
+      _mapToken(node.extendsKeyword), _cloneNode(node.superclass));
+
+  @override
+  FieldDeclaration visitFieldDeclaration(FieldDeclaration node) =>
+      new FieldDeclaration(_cloneNode(node.documentationComment),
+          _cloneNodeList(node.metadata), _mapToken(node.staticKeyword),
+          _cloneNode(node.fields), _mapToken(node.semicolon));
+
+  @override
+  FieldFormalParameter visitFieldFormalParameter(FieldFormalParameter node) =>
+      new FieldFormalParameter(_cloneNode(node.documentationComment),
+          _cloneNodeList(node.metadata), _mapToken(node.keyword),
+          _cloneNode(node.type), _mapToken(node.thisKeyword),
+          _mapToken(node.period), _cloneNode(node.identifier),
+          _cloneNode(node.typeParameters), _cloneNode(node.parameters));
+
+  @override
+  ForEachStatement visitForEachStatement(ForEachStatement node) {
+    DeclaredIdentifier loopVariable = node.loopVariable;
+    if (loopVariable == null) {
+      return new ForEachStatement.withReference(_mapToken(node.awaitKeyword),
+          _mapToken(node.forKeyword), _mapToken(node.leftParenthesis),
+          _cloneNode(node.identifier), _mapToken(node.inKeyword),
+          _cloneNode(node.iterable), _mapToken(node.rightParenthesis),
+          _cloneNode(node.body));
+    }
+    return new ForEachStatement.withDeclaration(_mapToken(node.awaitKeyword),
+        _mapToken(node.forKeyword), _mapToken(node.leftParenthesis),
+        _cloneNode(loopVariable), _mapToken(node.inKeyword),
+        _cloneNode(node.iterable), _mapToken(node.rightParenthesis),
+        _cloneNode(node.body));
+  }
+
+  @override
+  FormalParameterList visitFormalParameterList(FormalParameterList node) =>
+      new FormalParameterList(_mapToken(node.leftParenthesis),
+          _cloneNodeList(node.parameters), _mapToken(node.leftDelimiter),
+          _mapToken(node.rightDelimiter), _mapToken(node.rightParenthesis));
+
+  @override
+  ForStatement visitForStatement(ForStatement node) => new ForStatement(
+      _mapToken(node.forKeyword), _mapToken(node.leftParenthesis),
+      _cloneNode(node.variables), _cloneNode(node.initialization),
+      _mapToken(node.leftSeparator), _cloneNode(node.condition),
+      _mapToken(node.rightSeparator), _cloneNodeList(node.updaters),
+      _mapToken(node.rightParenthesis), _cloneNode(node.body));
+
+  @override
+  FunctionDeclaration visitFunctionDeclaration(FunctionDeclaration node) =>
+      new FunctionDeclaration(_cloneNode(node.documentationComment),
+          _cloneNodeList(node.metadata), _mapToken(node.externalKeyword),
+          _cloneNode(node.returnType), _mapToken(node.propertyKeyword),
+          _cloneNode(node.name), _cloneNode(node.functionExpression));
+
+  @override
+  FunctionDeclarationStatement visitFunctionDeclarationStatement(
+          FunctionDeclarationStatement node) =>
+      new FunctionDeclarationStatement(_cloneNode(node.functionDeclaration));
+
+  @override
+  FunctionExpression visitFunctionExpression(FunctionExpression node) {
+    FunctionExpression copy = new FunctionExpression(
+        _cloneNode(node.typeParameters), _cloneNode(node.parameters),
+        _cloneNode(node.body));
+    copy.element = node.element;
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  FunctionExpressionInvocation visitFunctionExpressionInvocation(
+      FunctionExpressionInvocation node) {
+    FunctionExpressionInvocation copy = new FunctionExpressionInvocation(
+        _cloneNode(node.function), _cloneNode(node.typeArguments),
+        _cloneNode(node.argumentList));
+    copy.propagatedElement = node.propagatedElement;
+    copy.propagatedType = node.propagatedType;
+    copy.staticElement = node.staticElement;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  FunctionTypeAlias visitFunctionTypeAlias(FunctionTypeAlias node) =>
+      new FunctionTypeAlias(_cloneNode(node.documentationComment),
+          _cloneNodeList(node.metadata), _mapToken(node.typedefKeyword),
+          _cloneNode(node.returnType), _cloneNode(node.name),
+          _cloneNode(node.typeParameters), _cloneNode(node.parameters),
+          _mapToken(node.semicolon));
+
+  @override
+  FunctionTypedFormalParameter visitFunctionTypedFormalParameter(
+      FunctionTypedFormalParameter node) => new FunctionTypedFormalParameter(
+      _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+      _cloneNode(node.returnType), _cloneNode(node.identifier),
+      _cloneNode(node.typeParameters), _cloneNode(node.parameters));
+
+  @override
+  HideCombinator visitHideCombinator(HideCombinator node) => new HideCombinator(
+      _mapToken(node.keyword), _cloneNodeList(node.hiddenNames));
+
+  @override
+  IfStatement visitIfStatement(IfStatement node) => new IfStatement(
+      _mapToken(node.ifKeyword), _mapToken(node.leftParenthesis),
+      _cloneNode(node.condition), _mapToken(node.rightParenthesis),
+      _cloneNode(node.thenStatement), _mapToken(node.elseKeyword),
+      _cloneNode(node.elseStatement));
+
+  @override
+  ImplementsClause visitImplementsClause(ImplementsClause node) =>
+      new ImplementsClause(
+          _mapToken(node.implementsKeyword), _cloneNodeList(node.interfaces));
+
+  @override
+  ImportDirective visitImportDirective(ImportDirective node) =>
+      new ImportDirective(_cloneNode(node.documentationComment),
+          _cloneNodeList(node.metadata), _mapToken(node.keyword),
+          _cloneNode(node.uri), _mapToken(node.deferredKeyword),
+          _mapToken(node.asKeyword), _cloneNode(node.prefix),
+          _cloneNodeList(node.combinators), _mapToken(node.semicolon));
+
+  @override
+  IndexExpression visitIndexExpression(IndexExpression node) {
+    Token period = _mapToken(node.period);
+    IndexExpression copy;
+    if (period == null) {
+      copy = new IndexExpression.forTarget(_cloneNode(node.target),
+          _mapToken(node.leftBracket), _cloneNode(node.index),
+          _mapToken(node.rightBracket));
+    } else {
+      copy = new IndexExpression.forCascade(period, _mapToken(node.leftBracket),
+          _cloneNode(node.index), _mapToken(node.rightBracket));
+    }
+    copy.auxiliaryElements = node.auxiliaryElements;
+    copy.propagatedElement = node.propagatedElement;
+    copy.propagatedType = node.propagatedType;
+    copy.staticElement = node.staticElement;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  InstanceCreationExpression visitInstanceCreationExpression(
+      InstanceCreationExpression node) {
+    InstanceCreationExpression copy = new InstanceCreationExpression(
+        _mapToken(node.keyword), _cloneNode(node.constructorName),
+        _cloneNode(node.argumentList));
+    copy.propagatedType = node.propagatedType;
+    copy.staticElement = node.staticElement;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  IntegerLiteral visitIntegerLiteral(IntegerLiteral node) {
+    IntegerLiteral copy =
+        new IntegerLiteral(_mapToken(node.literal), node.value);
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  InterpolationExpression visitInterpolationExpression(
+      InterpolationExpression node) => new InterpolationExpression(
+      _mapToken(node.leftBracket), _cloneNode(node.expression),
+      _mapToken(node.rightBracket));
+
+  @override
+  InterpolationString visitInterpolationString(InterpolationString node) =>
+      new InterpolationString(_mapToken(node.contents), node.value);
+
+  @override
+  IsExpression visitIsExpression(IsExpression node) {
+    IsExpression copy = new IsExpression(_cloneNode(node.expression),
+        _mapToken(node.isOperator), _mapToken(node.notOperator),
+        _cloneNode(node.type));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  Label visitLabel(Label node) =>
+      new Label(_cloneNode(node.label), _mapToken(node.colon));
+
+  @override
+  LabeledStatement visitLabeledStatement(LabeledStatement node) =>
+      new LabeledStatement(
+          _cloneNodeList(node.labels), _cloneNode(node.statement));
+
+  @override
+  LibraryDirective visitLibraryDirective(LibraryDirective node) =>
+      new LibraryDirective(_cloneNode(node.documentationComment),
+          _cloneNodeList(node.metadata), _mapToken(node.libraryKeyword),
+          _cloneNode(node.name), _mapToken(node.semicolon));
+
+  @override
+  LibraryIdentifier visitLibraryIdentifier(LibraryIdentifier node) {
+    LibraryIdentifier copy =
+        new LibraryIdentifier(_cloneNodeList(node.components));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  ListLiteral visitListLiteral(ListLiteral node) {
+    ListLiteral copy = new ListLiteral(_mapToken(node.constKeyword),
+        _cloneNode(node.typeArguments), _mapToken(node.leftBracket),
+        _cloneNodeList(node.elements), _mapToken(node.rightBracket));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  MapLiteral visitMapLiteral(MapLiteral node) {
+    MapLiteral copy = new MapLiteral(_mapToken(node.constKeyword),
+        _cloneNode(node.typeArguments), _mapToken(node.leftBracket),
+        _cloneNodeList(node.entries), _mapToken(node.rightBracket));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  MapLiteralEntry visitMapLiteralEntry(
+      MapLiteralEntry node) => new MapLiteralEntry(
+      _cloneNode(node.key), _mapToken(node.separator), _cloneNode(node.value));
+
+  @override
+  MethodDeclaration visitMethodDeclaration(MethodDeclaration node) =>
+      new MethodDeclaration(_cloneNode(node.documentationComment),
+          _cloneNodeList(node.metadata), _mapToken(node.externalKeyword),
+          _mapToken(node.modifierKeyword), _cloneNode(node.returnType),
+          _mapToken(node.propertyKeyword), _mapToken(node.operatorKeyword),
+          _cloneNode(node.name), _cloneNode(node._typeParameters),
+          _cloneNode(node.parameters), _cloneNode(node.body));
+
+  @override
+  MethodInvocation visitMethodInvocation(MethodInvocation node) {
+    MethodInvocation copy = new MethodInvocation(_cloneNode(node.target),
+        _mapToken(node.operator), _cloneNode(node.methodName),
+        _cloneNode(node.typeArguments), _cloneNode(node.argumentList));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  NamedExpression visitNamedExpression(NamedExpression node) {
+    NamedExpression copy =
+        new NamedExpression(_cloneNode(node.name), _cloneNode(node.expression));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  AstNode visitNativeClause(NativeClause node) =>
+      new NativeClause(_mapToken(node.nativeKeyword), _cloneNode(node.name));
+
+  @override
+  NativeFunctionBody visitNativeFunctionBody(NativeFunctionBody node) =>
+      new NativeFunctionBody(_mapToken(node.nativeKeyword),
+          _cloneNode(node.stringLiteral), _mapToken(node.semicolon));
+
+  @override
+  NullLiteral visitNullLiteral(NullLiteral node) {
+    NullLiteral copy = new NullLiteral(_mapToken(node.literal));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  ParenthesizedExpression visitParenthesizedExpression(
+      ParenthesizedExpression node) {
+    ParenthesizedExpression copy = new ParenthesizedExpression(
+        _mapToken(node.leftParenthesis), _cloneNode(node.expression),
+        _mapToken(node.rightParenthesis));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  PartDirective visitPartDirective(PartDirective node) {
+    PartDirective copy = new PartDirective(
+        _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+        _mapToken(node.partKeyword), _cloneNode(node.uri),
+        _mapToken(node.semicolon));
+    copy.element = node.element;
+    return copy;
+  }
+
+  @override
+  PartOfDirective visitPartOfDirective(PartOfDirective node) {
+    PartOfDirective copy = new PartOfDirective(
+        _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+        _mapToken(node.partKeyword), _mapToken(node.ofKeyword),
+        _cloneNode(node.libraryName), _mapToken(node.semicolon));
+    copy.element = node.element;
+    return copy;
+  }
+
+  @override
+  PostfixExpression visitPostfixExpression(PostfixExpression node) {
+    PostfixExpression copy = new PostfixExpression(
+        _cloneNode(node.operand), _mapToken(node.operator));
+    copy.propagatedElement = node.propagatedElement;
+    copy.propagatedType = node.propagatedType;
+    copy.staticElement = node.staticElement;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  PrefixedIdentifier visitPrefixedIdentifier(PrefixedIdentifier node) {
+    PrefixedIdentifier copy = new PrefixedIdentifier(_cloneNode(node.prefix),
+        _mapToken(node.period), _cloneNode(node.identifier));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  PrefixExpression visitPrefixExpression(PrefixExpression node) {
+    PrefixExpression copy = new PrefixExpression(
+        _mapToken(node.operator), _cloneNode(node.operand));
+    copy.propagatedElement = node.propagatedElement;
+    copy.propagatedType = node.propagatedType;
+    copy.staticElement = node.staticElement;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  PropertyAccess visitPropertyAccess(PropertyAccess node) {
+    PropertyAccess copy = new PropertyAccess(_cloneNode(node.target),
+        _mapToken(node.operator), _cloneNode(node.propertyName));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  RedirectingConstructorInvocation visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) {
+    RedirectingConstructorInvocation copy =
+        new RedirectingConstructorInvocation(_mapToken(node.thisKeyword),
+            _mapToken(node.period), _cloneNode(node.constructorName),
+            _cloneNode(node.argumentList));
+    copy.staticElement = node.staticElement;
+    return copy;
+  }
+
+  @override
+  RethrowExpression visitRethrowExpression(RethrowExpression node) {
+    RethrowExpression copy =
+        new RethrowExpression(_mapToken(node.rethrowKeyword));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  ReturnStatement visitReturnStatement(ReturnStatement node) =>
+      new ReturnStatement(_mapToken(node.returnKeyword),
+          _cloneNode(node.expression), _mapToken(node.semicolon));
+
+  @override
+  ScriptTag visitScriptTag(ScriptTag node) =>
+      new ScriptTag(_mapToken(node.scriptTag));
+
+  @override
+  ShowCombinator visitShowCombinator(ShowCombinator node) => new ShowCombinator(
+      _mapToken(node.keyword), _cloneNodeList(node.shownNames));
+
+  @override
+  SimpleFormalParameter visitSimpleFormalParameter(
+      SimpleFormalParameter node) => new SimpleFormalParameter(
+      _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+      _mapToken(node.keyword), _cloneNode(node.type),
+      _cloneNode(node.identifier));
+
+  @override
+  SimpleIdentifier visitSimpleIdentifier(SimpleIdentifier node) {
+    Token mappedToken = _mapToken(node.token);
+    if (mappedToken == null) {
+      // This only happens for SimpleIdentifiers created by the parser as part
+      // of scanning documentation comments (the tokens for those identifiers
+      // are not in the original token stream and hence do not get copied).
+      // This extra check can be removed if the scanner is changed to scan
+      // documentation comments for the parser.
+      mappedToken = node.token;
+    }
+    SimpleIdentifier copy = new SimpleIdentifier(mappedToken);
+    copy.auxiliaryElements = node.auxiliaryElements;
+    copy.propagatedElement = node.propagatedElement;
+    copy.propagatedType = node.propagatedType;
+    copy.staticElement = node.staticElement;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  SimpleStringLiteral visitSimpleStringLiteral(SimpleStringLiteral node) {
+    SimpleStringLiteral copy =
+        new SimpleStringLiteral(_mapToken(node.literal), node.value);
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  StringInterpolation visitStringInterpolation(StringInterpolation node) {
+    StringInterpolation copy =
+        new StringInterpolation(_cloneNodeList(node.elements));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  SuperConstructorInvocation visitSuperConstructorInvocation(
+      SuperConstructorInvocation node) {
+    SuperConstructorInvocation copy = new SuperConstructorInvocation(
+        _mapToken(node.superKeyword), _mapToken(node.period),
+        _cloneNode(node.constructorName), _cloneNode(node.argumentList));
+    copy.staticElement = node.staticElement;
+    return copy;
+  }
+
+  @override
+  SuperExpression visitSuperExpression(SuperExpression node) {
+    SuperExpression copy = new SuperExpression(_mapToken(node.superKeyword));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  SwitchCase visitSwitchCase(SwitchCase node) => new SwitchCase(
+      _cloneNodeList(node.labels), _mapToken(node.keyword),
+      _cloneNode(node.expression), _mapToken(node.colon),
+      _cloneNodeList(node.statements));
+
+  @override
+  SwitchDefault visitSwitchDefault(SwitchDefault node) => new SwitchDefault(
+      _cloneNodeList(node.labels), _mapToken(node.keyword),
+      _mapToken(node.colon), _cloneNodeList(node.statements));
+
+  @override
+  SwitchStatement visitSwitchStatement(SwitchStatement node) =>
+      new SwitchStatement(_mapToken(node.switchKeyword),
+          _mapToken(node.leftParenthesis), _cloneNode(node.expression),
+          _mapToken(node.rightParenthesis), _mapToken(node.leftBracket),
+          _cloneNodeList(node.members), _mapToken(node.rightBracket));
+
+  @override
+  AstNode visitSymbolLiteral(SymbolLiteral node) {
+    SymbolLiteral copy = new SymbolLiteral(
+        _mapToken(node.poundSign), _mapTokens(node.components));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  ThisExpression visitThisExpression(ThisExpression node) {
+    ThisExpression copy = new ThisExpression(_mapToken(node.thisKeyword));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  ThrowExpression visitThrowExpression(ThrowExpression node) {
+    ThrowExpression copy = new ThrowExpression(
+        _mapToken(node.throwKeyword), _cloneNode(node.expression));
+    copy.propagatedType = node.propagatedType;
+    copy.staticType = node.staticType;
+    return copy;
+  }
+
+  @override
+  TopLevelVariableDeclaration visitTopLevelVariableDeclaration(
+      TopLevelVariableDeclaration node) => new TopLevelVariableDeclaration(
+      _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+      _cloneNode(node.variables), _mapToken(node.semicolon));
+
+  @override
+  TryStatement visitTryStatement(TryStatement node) => new TryStatement(
+      _mapToken(node.tryKeyword), _cloneNode(node.body),
+      _cloneNodeList(node.catchClauses), _mapToken(node.finallyKeyword),
+      _cloneNode(node.finallyBlock));
+
+  @override
+  TypeArgumentList visitTypeArgumentList(TypeArgumentList node) =>
+      new TypeArgumentList(_mapToken(node.leftBracket),
+          _cloneNodeList(node.arguments), _mapToken(node.rightBracket));
+
+  @override
+  TypeName visitTypeName(TypeName node) {
+    TypeName copy =
+        new TypeName(_cloneNode(node.name), _cloneNode(node.typeArguments));
+    copy.type = node.type;
+    return copy;
+  }
+
+  @override
+  TypeParameter visitTypeParameter(TypeParameter node) => new TypeParameter(
+      _cloneNode(node.documentationComment), _cloneNodeList(node.metadata),
+      _cloneNode(node.name), _mapToken(node.extendsKeyword),
+      _cloneNode(node.bound));
+
+  @override
+  TypeParameterList visitTypeParameterList(TypeParameterList node) =>
+      new TypeParameterList(_mapToken(node.leftBracket),
+          _cloneNodeList(node.typeParameters), _mapToken(node.rightBracket));
+
+  @override
+  VariableDeclaration visitVariableDeclaration(VariableDeclaration node) =>
+      new VariableDeclaration(_cloneNode(node.name), _mapToken(node.equals),
+          _cloneNode(node.initializer));
+
+  @override
+  VariableDeclarationList visitVariableDeclarationList(
+      VariableDeclarationList node) => new VariableDeclarationList(null,
+      _cloneNodeList(node.metadata), _mapToken(node.keyword),
+      _cloneNode(node.type), _cloneNodeList(node.variables));
+
+  @override
+  VariableDeclarationStatement visitVariableDeclarationStatement(
+      VariableDeclarationStatement node) => new VariableDeclarationStatement(
+      _cloneNode(node.variables), _mapToken(node.semicolon));
+
+  @override
+  WhileStatement visitWhileStatement(WhileStatement node) => new WhileStatement(
+      _mapToken(node.whileKeyword), _mapToken(node.leftParenthesis),
+      _cloneNode(node.condition), _mapToken(node.rightParenthesis),
+      _cloneNode(node.body));
+
+  @override
+  WithClause visitWithClause(WithClause node) => new WithClause(
+      _mapToken(node.withKeyword), _cloneNodeList(node.mixinTypes));
+
+  @override
+  YieldStatement visitYieldStatement(YieldStatement node) => new YieldStatement(
+      _mapToken(node.yieldKeyword), _mapToken(node.star),
+      _cloneNode(node.expression), _mapToken(node.semicolon));
+
+  AstNode _cloneNode(AstNode node) {
+    if (node == null) {
+      return null;
+    }
+    if (identical(node, _oldNode)) {
+      return _newNode;
+    }
+    return node.accept(this) as AstNode;
+  }
+
+  List _cloneNodeList(NodeList nodes) {
+    List clonedNodes = new List();
+    for (AstNode node in nodes) {
+      clonedNodes.add(_cloneNode(node));
+    }
+    return clonedNodes;
+  }
+
+  Token _mapToken(Token oldToken) {
+    if (oldToken == null) {
+      return null;
+    }
+    return _tokenMap.get(oldToken);
+  }
+
+  List<Token> _mapTokens(List<Token> oldTokens) {
+    List<Token> newTokens = new List<Token>(oldTokens.length);
+    for (int index = 0; index < newTokens.length; index++) {
+      newTokens[index] = _mapToken(oldTokens[index]);
+    }
+    return newTokens;
+  }
+}
+
+/**
+ * An index expression.
+ *
+ * > indexExpression ::=
+ * >     [Expression] '[' [Expression] ']'
+ */
+class IndexExpression extends Expression {
+  /**
+   * The expression used to compute the object being indexed, or `null` if this
+   * index expression is part of a cascade expression.
+   */
+  Expression _target;
+
+  /**
+   * The period ("..") before a cascaded index expression, or `null` if this
+   * index expression is not part of a cascade expression.
+   */
+  Token period;
+
+  /**
+   * The left square bracket.
+   */
+  Token leftBracket;
+
+  /**
+   * The expression used to compute the index.
+   */
+  Expression _index;
+
+  /**
+   * The right square bracket.
+   */
+  Token rightBracket;
+
+  /**
+   * The element associated with the operator based on the static type of the
+   * target, or `null` if the AST structure has not been resolved or if the
+   * operator could not be resolved.
+   */
+  MethodElement staticElement;
+
+  /**
+   * The element associated with the operator based on the propagated type of
+   * the target, or `null` if the AST structure has not been resolved or if the
+   * operator could not be resolved.
+   */
+  MethodElement propagatedElement;
+
+  /**
+   * If this expression is both in a getter and setter context, the
+   * [AuxiliaryElements] will be set to hold onto the static and propagated
+   * information. The auxiliary element will hold onto the elements from the
+   * getter context.
+   */
+  AuxiliaryElements auxiliaryElements = null;
+
+  /**
+   * Initialize a newly created index expression.
+   */
+  IndexExpression.forCascade(
+      this.period, this.leftBracket, Expression index, this.rightBracket) {
+    _index = _becomeParentOf(index);
+  }
+
+  /**
+   * Initialize a newly created index expression.
+   */
+  IndexExpression.forTarget(Expression target, this.leftBracket,
+      Expression index, this.rightBracket) {
+    _target = _becomeParentOf(target);
+    _index = _becomeParentOf(index);
+  }
+
+  @override
+  Token get beginToken {
+    if (_target != null) {
+      return _target.beginToken;
+    }
+    return period;
+  }
+
+  /**
+   * Return the best element available for this operator. If resolution was able
+   * to find a better element based on type propagation, that element will be
+   * returned. Otherwise, the element found using the result of static analysis
+   * will be returned. If resolution has not been performed, then `null` will be
+   * returned.
+   */
+  MethodElement get bestElement {
+    MethodElement element = propagatedElement;
+    if (element == null) {
+      element = staticElement;
+    }
+    return element;
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(_target)
+    ..add(period)
+    ..add(leftBracket)
+    ..add(_index)
+    ..add(rightBracket);
+
+  @override
+  Token get endToken => rightBracket;
+
+  /**
+   * Return the expression used to compute the index.
+   */
+  Expression get index => _index;
+
+  /**
+   * Set the expression used to compute the index to the given [expression].
+   */
+  void set index(Expression expression) {
+    _index = _becomeParentOf(expression);
+  }
+
+  @override
+  bool get isAssignable => true;
+
+  /**
+   * Return `true` if this expression is cascaded. If it is, then the target of
+   * this expression is not stored locally but is stored in the nearest ancestor
+   * that is a [CascadeExpression].
+   */
+  bool get isCascaded => period != null;
+
+  @override
+  int get precedence => 15;
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on propagated type information, then return the parameter
+   * element representing the parameter to which the value of the index
+   * expression will be bound. Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.propagatedParameterElement"
+  ParameterElement get propagatedParameterElementForIndex {
+    return _propagatedParameterElementForIndex;
+  }
+
+  /**
+   * Return the expression used to compute the object being indexed. If this
+   * index expression is not part of a cascade expression, then this is the same
+   * as [target]. If this index expression is part of a cascade expression, then
+   * the target expression stored with the cascade expression is returned.
+   */
+  Expression get realTarget {
+    if (isCascaded) {
+      AstNode ancestor = parent;
+      while (ancestor is! CascadeExpression) {
+        if (ancestor == null) {
+          return _target;
+        }
+        ancestor = ancestor.parent;
+      }
+      return (ancestor as CascadeExpression).target;
+    }
+    return _target;
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on static type information, then return the parameter element
+   * representing the parameter to which the value of the index expression will
+   * be bound. Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.propagatedParameterElement"
+  ParameterElement get staticParameterElementForIndex {
+    return _staticParameterElementForIndex;
+  }
+
+  /**
+   * Return the expression used to compute the object being indexed, or `null`
+   * if this index expression is part of a cascade expression.
+   *
+   * Use [realTarget] to get the target independent of whether this is part of a
+   * cascade expression.
+   */
+  Expression get target => _target;
+
+  /**
+   * Set the expression used to compute the object being indexed to the given
+   * [expression].
+   */
+  void set target(Expression expression) {
+    _target = _becomeParentOf(expression);
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on propagated type information, then return the parameter
+   * element representing the parameter to which the value of the index
+   * expression will be bound. Otherwise, return `null`.
+   */
+  ParameterElement get _propagatedParameterElementForIndex {
+    if (propagatedElement == null) {
+      return null;
+    }
+    List<ParameterElement> parameters = propagatedElement.parameters;
+    if (parameters.length < 1) {
+      return null;
+    }
+    return parameters[0];
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on static type information, then return the parameter element
+   * representing the parameter to which the value of the index expression will
+   * be bound. Otherwise, return `null`.
+   */
+  ParameterElement get _staticParameterElementForIndex {
+    if (staticElement == null) {
+      return null;
+    }
+    List<ParameterElement> parameters = staticElement.parameters;
+    if (parameters.length < 1) {
+      return null;
+    }
+    return parameters[0];
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitIndexExpression(this);
+
+  /**
+   * Return `true` if this expression is computing a right-hand value (that is,
+   * if this expression is in a context where the operator '[]' will be
+   * invoked).
+   *
+   * Note that [inGetterContext] and [inSetterContext] are not opposites, nor
+   * are they mutually exclusive. In other words, it is possible for both
+   * methods to return `true` when invoked on the same node.
+   */
+  bool inGetterContext() {
+    // TODO(brianwilkerson) Convert this to a getter.
+    AstNode parent = this.parent;
+    if (parent is AssignmentExpression) {
+      AssignmentExpression assignment = parent;
+      if (identical(assignment.leftHandSide, this) &&
+          assignment.operator.type == TokenType.EQ) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  /**
+   * Return `true` if this expression is computing a left-hand value (that is,
+   * if this expression is in a context where the operator '[]=' will be
+   * invoked).
+   *
+   * Note that [inGetterContext] and [inSetterContext] are not opposites, nor
+   * are they mutually exclusive. In other words, it is possible for both
+   * methods to return `true` when invoked on the same node.
+   */
+  bool inSetterContext() {
+    // TODO(brianwilkerson) Convert this to a getter.
+    AstNode parent = this.parent;
+    if (parent is PrefixExpression) {
+      return parent.operator.type.isIncrementOperator;
+    } else if (parent is PostfixExpression) {
+      return true;
+    } else if (parent is AssignmentExpression) {
+      return identical(parent.leftHandSide, this);
+    }
+    return false;
+  }
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_target, visitor);
+    _safelyVisitChild(_index, visitor);
+  }
+}
+
+/**
+ * An instance creation expression.
+ *
+ * > newExpression ::=
+ * >     ('new' | 'const') [TypeName] ('.' [SimpleIdentifier])? [ArgumentList]
+ */
+class InstanceCreationExpression extends Expression {
+  /**
+   * The 'new' or 'const' keyword used to indicate how an object should be
+   * created.
+   */
+  Token keyword;
+
+  /**
+   * The name of the constructor to be invoked.
+   */
+  ConstructorName _constructorName;
+
+  /**
+   * The list of arguments to the constructor.
+   */
+  ArgumentList _argumentList;
+
+  /**
+   * The element associated with the constructor based on static type
+   * information, or `null` if the AST structure has not been resolved or if the
+   * constructor could not be resolved.
+   */
+  ConstructorElement staticElement;
+
+  /**
+   * Initialize a newly created instance creation expression.
+   */
+  InstanceCreationExpression(this.keyword, ConstructorName constructorName,
+      ArgumentList argumentList) {
+    _constructorName = _becomeParentOf(constructorName);
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  /**
+   * Return the list of arguments to the constructor.
+   */
+  ArgumentList get argumentList => _argumentList;
+
+  /**
+   * Set the list of arguments to the constructor to the given [argumentList].
+   */
+  void set argumentList(ArgumentList argumentList) {
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  @override
+  Token get beginToken => keyword;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(keyword)
+    ..add(_constructorName)
+    ..add(_argumentList);
+
+  /**
+   * Return the name of the constructor to be invoked.
+   */
+  ConstructorName get constructorName => _constructorName;
+
+  /**
+   * Set the name of the constructor to be invoked to the given [name].
+   */
+  void set constructorName(ConstructorName name) {
+    _constructorName = _becomeParentOf(name);
+  }
+
+  @override
+  Token get endToken => _argumentList.endToken;
+
+  /**
+   * Return `true` if this creation expression is used to invoke a constant
+   * constructor.
+   */
+  bool get isConst => keyword is KeywordToken &&
+      (keyword as KeywordToken).keyword == Keyword.CONST;
+
+  @override
+  int get precedence => 16;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitInstanceCreationExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_constructorName, visitor);
+    _safelyVisitChild(_argumentList, visitor);
+  }
+}
+
+/**
+ * An integer literal expression.
+ *
+ * > integerLiteral ::=
+ * >     decimalIntegerLiteral
+ * >   | hexidecimalIntegerLiteral
+ * >
+ * > decimalIntegerLiteral ::=
+ * >     decimalDigit+
+ * >
+ * > hexidecimalIntegerLiteral ::=
+ * >     '0x' hexidecimalDigit+
+ * >   | '0X' hexidecimalDigit+
+ */
+class IntegerLiteral extends Literal {
+  /**
+   * The token representing the literal.
+   */
+  Token literal;
+
+  /**
+   * The value of the literal.
+   */
+  int value = 0;
+
+  /**
+   * Initialize a newly created integer literal.
+   */
+  IntegerLiteral(this.literal, this.value);
+
+  @override
+  Token get beginToken => literal;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(literal);
+
+  @override
+  Token get endToken => literal;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitIntegerLiteral(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+}
+
+/**
+ * A node within a [StringInterpolation].
+ *
+ * > interpolationElement ::=
+ * >     [InterpolationExpression]
+ * >   | [InterpolationString]
+ */
+abstract class InterpolationElement extends AstNode {}
+
+/**
+ * An expression embedded in a string interpolation.
+ *
+ * > interpolationExpression ::=
+ * >     '$' [SimpleIdentifier]
+ * >   | '$' '{' [Expression] '}'
+ */
+class InterpolationExpression extends InterpolationElement {
+  /**
+   * The token used to introduce the interpolation expression; either '$' if the
+   * expression is a simple identifier or '${' if the expression is a full
+   * expression.
+   */
+  Token leftBracket;
+
+  /**
+   * The expression to be evaluated for the value to be converted into a string.
+   */
+  Expression _expression;
+
+  /**
+   * The right curly bracket, or `null` if the expression is an identifier
+   * without brackets.
+   */
+  Token rightBracket;
+
+  /**
+   * Initialize a newly created interpolation expression.
+   */
+  InterpolationExpression(
+      this.leftBracket, Expression expression, this.rightBracket) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get beginToken => leftBracket;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(leftBracket)
+    ..add(_expression)
+    ..add(rightBracket);
+
+  @override
+  Token get endToken {
+    if (rightBracket != null) {
+      return rightBracket;
+    }
+    return _expression.endToken;
+  }
+
+  /**
+   * Return the expression to be evaluated for the value to be converted into a
+   * string.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression to be evaluated for the value to be converted into a
+   * string to the given [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitInterpolationExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+  }
+}
+
+/**
+ * A non-empty substring of an interpolated string.
+ *
+ * > interpolationString ::=
+ * >     characters
+ */
+class InterpolationString extends InterpolationElement {
+  /**
+   * The characters that will be added to the string.
+   */
+  Token contents;
+
+  /**
+   * The value of the literal.
+   */
+  String value;
+
+  /**
+   * Initialize a newly created string of characters that are part of a string
+   * interpolation.
+   */
+  InterpolationString(this.contents, this.value);
+
+  @override
+  Token get beginToken => contents;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(contents);
+
+  /**
+   * Return the offset of the after-last contents character.
+   */
+  int get contentsEnd {
+    String lexeme = contents.lexeme;
+    return offset + new StringLexemeHelper(lexeme, true, true).end;
+  }
+
+  /**
+   * Return the offset of the first contents character.
+   */
+  int get contentsOffset {
+    int offset = contents.offset;
+    String lexeme = contents.lexeme;
+    return offset + new StringLexemeHelper(lexeme, true, true).start;
+  }
+
+  @override
+  Token get endToken => contents;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitInterpolationString(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {}
+}
+
+/**
+ * An is expression.
+ *
+ * > isExpression ::=
+ * >     [Expression] 'is' '!'? [TypeName]
+ */
+class IsExpression extends Expression {
+  /**
+   * The expression used to compute the value whose type is being tested.
+   */
+  Expression _expression;
+
+  /**
+   * The is operator.
+   */
+  Token isOperator;
+
+  /**
+   * The not operator, or `null` if the sense of the test is not negated.
+   */
+  Token notOperator;
+
+  /**
+   * The name of the type being tested for.
+   */
+  TypeName _type;
+
+  /**
+   * Initialize a newly created is expression. The [notOperator] can be `null`
+   * if the sense of the test is not negated.
+   */
+  IsExpression(
+      Expression expression, this.isOperator, this.notOperator, TypeName type) {
+    _expression = _becomeParentOf(expression);
+    _type = _becomeParentOf(type);
+  }
+
+  @override
+  Token get beginToken => _expression.beginToken;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(_expression)
+    ..add(isOperator)
+    ..add(notOperator)
+    ..add(_type);
+
+  @override
+  Token get endToken => _type.endToken;
+
+  /**
+   * Return the expression used to compute the value whose type is being tested.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression used to compute the value whose type is being tested to
+   * the given [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  int get precedence => 7;
+
+  /**
+   * Return the name of the type being tested for.
+   */
+  TypeName get type => _type;
+
+  /**
+   * Set the name of the type being tested for to the given [name].
+   */
+  void set type(TypeName name) {
+    _type = _becomeParentOf(name);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitIsExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+    _safelyVisitChild(_type, visitor);
+  }
+}
+
+/**
+ * A label on either a [LabeledStatement] or a [NamedExpression].
+ *
+ * > label ::=
+ * >     [SimpleIdentifier] ':'
+ */
+class Label extends AstNode {
+  /**
+   * The label being associated with the statement.
+   */
+  SimpleIdentifier _label;
+
+  /**
+   * The colon that separates the label from the statement.
+   */
+  Token colon;
+
+  /**
+   * Initialize a newly created label.
+   */
+  Label(SimpleIdentifier label, this.colon) {
+    _label = _becomeParentOf(label);
+  }
+
+  @override
+  Token get beginToken => _label.beginToken;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(_label)..add(colon);
+
+  @override
+  Token get endToken => colon;
+
+  /**
+   * Return the label being associated with the statement.
+   */
+  SimpleIdentifier get label => _label;
+
+  /**
+   * Set the label being associated with the statement to the given [label].
+   */
+  void set label(SimpleIdentifier label) {
+    _label = _becomeParentOf(label);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitLabel(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_label, visitor);
+  }
+}
+
+/**
+ * A statement that has a label associated with them.
+ *
+ * > labeledStatement ::=
+ * >    [Label]+ [Statement]
+ */
+class LabeledStatement extends Statement {
+  /**
+   * The labels being associated with the statement.
+   */
+  NodeList<Label> _labels;
+
+  /**
+   * The statement with which the labels are being associated.
+   */
+  Statement _statement;
+
+  /**
+   * Initialize a newly created labeled statement.
+   */
+  LabeledStatement(List<Label> labels, Statement statement) {
+    _labels = new NodeList<Label>(this, labels);
+    _statement = _becomeParentOf(statement);
+  }
+
+  @override
+  Token get beginToken {
+    if (!_labels.isEmpty) {
+      return _labels.beginToken;
+    }
+    return _statement.beginToken;
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..addAll(_labels)
+    ..add(_statement);
+
+  @override
+  Token get endToken => _statement.endToken;
+
+  /**
+   * Return the labels being associated with the statement.
+   */
+  NodeList<Label> get labels => _labels;
+
+  /**
+   * Return the statement with which the labels are being associated.
+   */
+  Statement get statement => _statement;
+
+  /**
+   * Set the statement with which the labels are being associated to the given
+   * [statement].
+   */
+  void set statement(Statement statement) {
+    _statement = _becomeParentOf(statement);
+  }
+
+  @override
+  Statement get unlabeled => _statement.unlabeled;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitLabeledStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _labels.accept(visitor);
+    _safelyVisitChild(_statement, visitor);
+  }
+}
+
+/**
+ * A library directive.
+ *
+ * > libraryDirective ::=
+ * >     [Annotation] 'library' [Identifier] ';'
+ */
+class LibraryDirective extends Directive {
+  /**
+   * The token representing the 'library' keyword.
+   */
+  Token libraryKeyword;
+
+  /**
+   * The name of the library being defined.
+   */
+  LibraryIdentifier _name;
+
+  /**
+   * The semicolon terminating the directive.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created library directive. Either or both of the
+   * [comment] and [metadata] can be `null` if the directive does not have the
+   * corresponding attribute.
+   */
+  LibraryDirective(Comment comment, List<Annotation> metadata,
+      this.libraryKeyword, LibraryIdentifier name, this.semicolon)
+      : super(comment, metadata) {
+    _name = _becomeParentOf(name);
+  }
+
+  @override
+  Iterable get childEntities =>
+      super._childEntities..add(libraryKeyword)..add(_name)..add(semicolon);
+
+  @override
+  Token get endToken => semicolon;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata => libraryKeyword;
+
+  @override
+  Token get keyword => libraryKeyword;
+
+  /**
+   * Return the token representing the 'library' token.
+   */
+  @deprecated // Use "this.libraryKeyword"
+  Token get libraryToken => libraryKeyword;
+
+  /**
+   * Set the token representing the 'library' token to the given [token].
+   */
+  @deprecated // Use "this.libraryKeyword"
+  set libraryToken(Token token) {
+    libraryKeyword = token;
+  }
+
+  /**
+   * Return the name of the library being defined.
+   */
+  LibraryIdentifier get name => _name;
+
+  /**
+   * Set the name of the library being defined to the given [name].
+   */
+  void set name(LibraryIdentifier name) {
+    _name = _becomeParentOf(name);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitLibraryDirective(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_name, visitor);
+  }
+}
+
+/**
+ * The identifier for a library.
+ *
+ * > libraryIdentifier ::=
+ * >     [SimpleIdentifier] ('.' [SimpleIdentifier])*
+ */
+class LibraryIdentifier extends Identifier {
+  /**
+   * The components of the identifier.
+   */
+  NodeList<SimpleIdentifier> _components;
+
+  /**
+   * Initialize a newly created prefixed identifier.
+   */
+  LibraryIdentifier(List<SimpleIdentifier> components) {
+    _components = new NodeList<SimpleIdentifier>(this, components);
+  }
+
+  @override
+  Token get beginToken => _components.beginToken;
+
+  @override
+  Element get bestElement => staticElement;
+
+  /**
+   * TODO(paulberry): add "." tokens.
+   */
+  @override
+  Iterable get childEntities => new ChildEntities()..addAll(_components);
+
+  /**
+   * Return the components of the identifier.
+   */
+  NodeList<SimpleIdentifier> get components => _components;
+
+  @override
+  Token get endToken => _components.endToken;
+
+  @override
+  String get name {
+    StringBuffer buffer = new StringBuffer();
+    bool needsPeriod = false;
+    for (SimpleIdentifier identifier in _components) {
+      if (needsPeriod) {
+        buffer.write(".");
+      } else {
+        needsPeriod = true;
+      }
+      buffer.write(identifier.name);
+    }
+    return buffer.toString();
+  }
+
+  @override
+  int get precedence => 15;
+
+  @override
+  Element get propagatedElement => null;
+
+  @override
+  Element get staticElement => null;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitLibraryIdentifier(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _components.accept(visitor);
+  }
+}
+
+/**
+ * A list literal.
+ *
+ * > listLiteral ::=
+ * >     'const'? ('<' [TypeName] '>')? '[' ([Expression] ','?)? ']'
+ */
+class ListLiteral extends TypedLiteral {
+  /**
+   * The left square bracket.
+   */
+  Token leftBracket;
+
+  /**
+   * The expressions used to compute the elements of the list.
+   */
+  NodeList<Expression> _elements;
+
+  /**
+   * The right square bracket.
+   */
+  Token rightBracket;
+
+  /**
+   * Initialize a newly created list literal. The [constKeyword] can be `null`
+   * if the literal is not a constant. The [typeArguments] can be `null` if no
+   * type arguments were declared. The list of [elements] can be `null` if the
+   * list is empty.
+   */
+  ListLiteral(Token constKeyword, TypeArgumentList typeArguments,
+      this.leftBracket, List<Expression> elements, this.rightBracket)
+      : super(constKeyword, typeArguments) {
+    _elements = new NodeList<Expression>(this, elements);
+  }
+
+  @override
+  Token get beginToken {
+    if (constKeyword != null) {
+      return constKeyword;
+    }
+    TypeArgumentList typeArguments = this.typeArguments;
+    if (typeArguments != null) {
+      return typeArguments.beginToken;
+    }
+    return leftBracket;
+  }
+
+  /**
+   * TODO(paulberry): add commas.
+   */
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(leftBracket)
+    ..addAll(_elements)
+    ..add(rightBracket);
+
+  /**
+   * Return the expressions used to compute the elements of the list.
+   */
+  NodeList<Expression> get elements => _elements;
+
+  @override
+  Token get endToken => rightBracket;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitListLiteral(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _elements.accept(visitor);
+  }
+}
+
+/**
+ * A node that represents a literal expression.
+ *
+ * > literal ::=
+ * >     [BooleanLiteral]
+ * >   | [DoubleLiteral]
+ * >   | [IntegerLiteral]
+ * >   | [ListLiteral]
+ * >   | [MapLiteral]
+ * >   | [NullLiteral]
+ * >   | [StringLiteral]
+ */
+abstract class Literal extends Expression {
+  @override
+  int get precedence => 16;
+}
+
+/**
+ * A literal map.
+ *
+ * > mapLiteral ::=
+ * >     'const'? ('<' [TypeName] (',' [TypeName])* '>')?
+ * >     '{' ([MapLiteralEntry] (',' [MapLiteralEntry])* ','?)? '}'
+ */
+class MapLiteral extends TypedLiteral {
+  /**
+   * The left curly bracket.
+   */
+  Token leftBracket;
+
+  /**
+   * The entries in the map.
+   */
+  NodeList<MapLiteralEntry> _entries;
+
+  /**
+   * The right curly bracket.
+   */
+  Token rightBracket;
+
+  /**
+   * Initialize a newly created map literal. The [constKeyword] can be `null` if
+   * the literal is not a constant. The [typeArguments] can be `null` if no type
+   * arguments were declared. The [entries] can be `null` if the map is empty.
+   */
+  MapLiteral(Token constKeyword, TypeArgumentList typeArguments,
+      this.leftBracket, List<MapLiteralEntry> entries, this.rightBracket)
+      : super(constKeyword, typeArguments) {
+    _entries = new NodeList<MapLiteralEntry>(this, entries);
+  }
+
+  @override
+  Token get beginToken {
+    if (constKeyword != null) {
+      return constKeyword;
+    }
+    TypeArgumentList typeArguments = this.typeArguments;
+    if (typeArguments != null) {
+      return typeArguments.beginToken;
+    }
+    return leftBracket;
+  }
+
+  /**
+   * TODO(paulberry): add commas.
+   */
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(leftBracket)
+    ..addAll(entries)
+    ..add(rightBracket);
+
+  @override
+  Token get endToken => rightBracket;
+
+  /**
+   * Return the entries in the map.
+   */
+  NodeList<MapLiteralEntry> get entries => _entries;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitMapLiteral(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _entries.accept(visitor);
+  }
+}
+
+/**
+ * A single key/value pair in a map literal.
+ *
+ * > mapLiteralEntry ::=
+ * >     [Expression] ':' [Expression]
+ */
+class MapLiteralEntry extends AstNode {
+  /**
+   * The expression computing the key with which the value will be associated.
+   */
+  Expression _key;
+
+  /**
+   * The colon that separates the key from the value.
+   */
+  Token separator;
+
+  /**
+   * The expression computing the value that will be associated with the key.
+   */
+  Expression _value;
+
+  /**
+   * Initialize a newly created map literal entry.
+   */
+  MapLiteralEntry(Expression key, this.separator, Expression value) {
+    _key = _becomeParentOf(key);
+    _value = _becomeParentOf(value);
+  }
+
+  @override
+  Token get beginToken => _key.beginToken;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_key)..add(separator)..add(_value);
+
+  @override
+  Token get endToken => _value.endToken;
+
+  /**
+   * Return the expression computing the key with which the value will be
+   * associated.
+   */
+  Expression get key => _key;
+
+  /**
+   * Set the expression computing the key with which the value will be
+   * associated to the given [string].
+   */
+  void set key(Expression string) {
+    _key = _becomeParentOf(string);
+  }
+
+  /**
+   * Return the expression computing the value that will be associated with the
+   * key.
+   */
+  Expression get value => _value;
+
+  /**
+   * Set the expression computing the value that will be associated with the key
+   * to the given [expression].
+   */
+  void set value(Expression expression) {
+    _value = _becomeParentOf(expression);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitMapLiteralEntry(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_key, visitor);
+    _safelyVisitChild(_value, visitor);
+  }
+}
+
+/**
+ * A method declaration.
+ *
+ * > methodDeclaration ::=
+ * >     methodSignature [FunctionBody]
+ * >
+ * > methodSignature ::=
+ * >     'external'? ('abstract' | 'static')? [Type]? ('get' | 'set')?
+ * >     methodName [TypeParameterList] [FormalParameterList]
+ * >
+ * > methodName ::=
+ * >     [SimpleIdentifier]
+ * >   | 'operator' [SimpleIdentifier]
+ */
+class MethodDeclaration extends ClassMember {
+  /**
+   * The token for the 'external' keyword, or `null` if the constructor is not
+   * external.
+   */
+  Token externalKeyword;
+
+  /**
+   * The token representing the 'abstract' or 'static' keyword, or `null` if
+   * neither modifier was specified.
+   */
+  Token modifierKeyword;
+
+  /**
+   * The return type of the method, or `null` if no return type was declared.
+   */
+  TypeName _returnType;
+
+  /**
+   * The token representing the 'get' or 'set' keyword, or `null` if this is a
+   * method declaration rather than a property declaration.
+   */
+  Token propertyKeyword;
+
+  /**
+   * The token representing the 'operator' keyword, or `null` if this method
+   * does not declare an operator.
+   */
+  Token operatorKeyword;
+
+  /**
+   * The name of the method.
+   */
+  SimpleIdentifier _name;
+
+  /**
+   * The type parameters associated with the method, or `null` if the method is
+   * not a generic method.
+   */
+  TypeParameterList _typeParameters;
+
+  /**
+   * The parameters associated with the method, or `null` if this method
+   * declares a getter.
+   */
+  FormalParameterList _parameters;
+
+  /**
+   * The body of the method.
+   */
+  FunctionBody _body;
+
+  /**
+   * Initialize a newly created method declaration. Either or both of the
+   * [comment] and [metadata] can be `null` if the declaration does not have the
+   * corresponding attribute. The [externalKeyword] can be `null` if the method
+   * is not external. The [modifierKeyword] can be `null` if the method is
+   * neither abstract nor static. The [returnType] can be `null` if no return
+   * type was specified. The [propertyKeyword] can be `null` if the method is
+   * neither a getter or a setter. The [operatorKeyword] can be `null` if the
+   * method does not implement an operator. The [parameters] must be `null` if
+   * this method declares a getter.
+   */
+  MethodDeclaration(Comment comment, List<Annotation> metadata,
+      this.externalKeyword, this.modifierKeyword, TypeName returnType,
+      this.propertyKeyword, this.operatorKeyword, SimpleIdentifier name,
+      TypeParameterList typeParameters, FormalParameterList parameters,
+      FunctionBody body)
+      : super(comment, metadata) {
+    _returnType = _becomeParentOf(returnType);
+    _name = _becomeParentOf(name);
+    _typeParameters = _becomeParentOf(typeParameters);
+    _parameters = _becomeParentOf(parameters);
+    _body = _becomeParentOf(body);
+  }
+
+  /**
+   * Return the body of the method.
+   */
+  FunctionBody get body => _body;
+
+  /**
+   * Set the body of the method to the given [functionBody].
+   */
+  void set body(FunctionBody functionBody) {
+    _body = _becomeParentOf(functionBody);
+  }
+
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(externalKeyword)
+    ..add(modifierKeyword)
+    ..add(_returnType)
+    ..add(propertyKeyword)
+    ..add(operatorKeyword)
+    ..add(_name)
+    ..add(_parameters)
+    ..add(_body);
+
+  /**
+   * Return the element associated with this method, or `null` if the AST
+   * structure has not been resolved. The element can either be a
+   * [MethodElement], if this represents the declaration of a normal method, or
+   * a [PropertyAccessorElement] if this represents the declaration of either a
+   * getter or a setter.
+   */
+  @override
+  ExecutableElement get element =>
+      _name != null ? (_name.staticElement as ExecutableElement) : null;
+
+  @override
+  Token get endToken => _body.endToken;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata {
+    if (modifierKeyword != null) {
+      return modifierKeyword;
+    } else if (_returnType != null) {
+      return _returnType.beginToken;
+    } else if (propertyKeyword != null) {
+      return propertyKeyword;
+    } else if (operatorKeyword != null) {
+      return operatorKeyword;
+    }
+    return _name.beginToken;
+  }
+
+  /**
+   * Return `true` if this method is declared to be an abstract method.
+   */
+  bool get isAbstract {
+    FunctionBody body = _body;
+    return externalKeyword == null &&
+        (body is EmptyFunctionBody && !body.semicolon.isSynthetic);
+  }
+
+  /**
+   * Return `true` if this method declares a getter.
+   */
+  bool get isGetter => propertyKeyword != null &&
+      (propertyKeyword as KeywordToken).keyword == Keyword.GET;
+
+  /**
+   * Return `true` if this method declares an operator.
+   */
+  bool get isOperator => operatorKeyword != null;
+
+  /**
+   * Return `true` if this method declares a setter.
+   */
+  bool get isSetter => propertyKeyword != null &&
+      (propertyKeyword as KeywordToken).keyword == Keyword.SET;
+
+  /**
+   * Return `true` if this method is declared to be a static method.
+   */
+  bool get isStatic => modifierKeyword != null &&
+      (modifierKeyword as KeywordToken).keyword == Keyword.STATIC;
+
+  /**
+   * Return the name of the method.
+   */
+  SimpleIdentifier get name => _name;
+
+  /**
+   * Set the name of the method to the given [identifier].
+   */
+  void set name(SimpleIdentifier identifier) {
+    _name = _becomeParentOf(identifier);
+  }
+
+  /**
+   * Return the parameters associated with the method, or `null` if this method
+   * declares a getter.
+   */
+  FormalParameterList get parameters => _parameters;
+
+  /**
+   * Set the parameters associated with the method to the given list of
+   * [parameters].
+   */
+  void set parameters(FormalParameterList parameters) {
+    _parameters = _becomeParentOf(parameters);
+  }
+
+  /**
+   * Return the return type of the method, or `null` if no return type was
+   * declared.
+   */
+  TypeName get returnType => _returnType;
+
+  /**
+   * Set the return type of the method to the given [typeName].
+   */
+  void set returnType(TypeName typeName) {
+    _returnType = _becomeParentOf(typeName);
+  }
+
+  /**
+   * Return the type parameters associated with this method, or `null` if this
+   * method is not a generic method.
+   */
+  TypeParameterList get typeParameters => _typeParameters;
+
+  /**
+   * Set the type parameters associated with this method to the given
+   * [typeParameters].
+   */
+  void set typeParameters(TypeParameterList typeParameters) {
+    _typeParameters = _becomeParentOf(typeParameters);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitMethodDeclaration(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_returnType, visitor);
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_typeParameters, visitor);
+    _safelyVisitChild(_parameters, visitor);
+    _safelyVisitChild(_body, visitor);
+  }
+}
+
+/**
+ * The invocation of either a function or a method. Invocations of functions
+ * resulting from evaluating an expression are represented by
+ * [FunctionExpressionInvocation] nodes. Invocations of getters and setters are
+ * represented by either [PrefixedIdentifier] or [PropertyAccess] nodes.
+ *
+ * > methodInvoction ::=
+ * >     ([Expression] '.')? [SimpleIdentifier] [TypeArgumentList]? [ArgumentList]
+ */
+class MethodInvocation extends Expression {
+  /**
+   * The expression producing the object on which the method is defined, or
+   * `null` if there is no target (that is, the target is implicitly `this`).
+   */
+  Expression _target;
+
+  /**
+   * The operator that separates the target from the method name, or `null`
+   * if there is no target. In an ordinary method invocation this will be a
+   * period ('.'). In a cascade section this will be the cascade operator
+   * ('..').
+   */
+  Token operator;
+
+  /**
+   * The name of the method being invoked.
+   */
+  SimpleIdentifier _methodName;
+
+  /**
+   * The type arguments to be applied to the method being invoked, or `null` if
+   * no type arguments were provided.
+   */
+  TypeArgumentList _typeArguments;
+
+  /**
+   * The list of arguments to the method.
+   */
+  ArgumentList _argumentList;
+
+  /**
+   * Initialize a newly created method invocation. The [target] and [operator]
+   * can be `null` if there is no target.
+   */
+  MethodInvocation(Expression target, this.operator,
+      SimpleIdentifier methodName, TypeArgumentList typeArguments,
+      ArgumentList argumentList) {
+    _target = _becomeParentOf(target);
+    _methodName = _becomeParentOf(methodName);
+    _typeArguments = _becomeParentOf(typeArguments);
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  /**
+   * Return the list of arguments to the method.
+   */
+  ArgumentList get argumentList => _argumentList;
+
+  /**
+   * Set the list of arguments to the method to the given [argumentList].
+   */
+  void set argumentList(ArgumentList argumentList) {
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  @override
+  Token get beginToken {
+    if (_target != null) {
+      return _target.beginToken;
+    } else if (operator != null) {
+      return operator;
+    }
+    return _methodName.beginToken;
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(_target)
+    ..add(operator)
+    ..add(_methodName)
+    ..add(_argumentList);
+
+  @override
+  Token get endToken => _argumentList.endToken;
+
+  /**
+   * Return `true` if this expression is cascaded. If it is, then the target of
+   * this expression is not stored locally but is stored in the nearest ancestor
+   * that is a [CascadeExpression].
+   */
+  bool get isCascaded =>
+      operator != null && operator.type == TokenType.PERIOD_PERIOD;
+
+  /**
+   * Return the name of the method being invoked.
+   */
+  SimpleIdentifier get methodName => _methodName;
+
+  /**
+   * Set the name of the method being invoked to the given [identifier].
+   */
+  void set methodName(SimpleIdentifier identifier) {
+    _methodName = _becomeParentOf(identifier);
+  }
+
+  /**
+   * The operator that separates the target from the method name, or `null`
+   * if there is no target. In an ordinary method invocation this will be a
+   * period ('.'). In a cascade section this will be the cascade operator
+   * ('..').
+   */
+  @deprecated // Use this.operator
+  Token get period => operator;
+
+  /**
+   * The operator that separates the target from the method name, or `null`
+   * if there is no target. In an ordinary method invocation this will be a
+   * period ('.'). In a cascade section this will be the cascade operator
+   * ('..').
+   */
+  @deprecated // Use this.operator
+  void set period(Token value) {
+    operator = value;
+  }
+
+  @override
+  int get precedence => 15;
+
+  /**
+   * Return the expression used to compute the receiver of the invocation. If
+   * this invocation is not part of a cascade expression, then this is the same
+   * as [target]. If this invocation is part of a cascade expression, then the
+   * target stored with the cascade expression is returned.
+   */
+  Expression get realTarget {
+    if (isCascaded) {
+      AstNode ancestor = parent;
+      while (ancestor is! CascadeExpression) {
+        if (ancestor == null) {
+          return _target;
+        }
+        ancestor = ancestor.parent;
+      }
+      return (ancestor as CascadeExpression).target;
+    }
+    return _target;
+  }
+
+  /**
+   * Return the expression producing the object on which the method is defined,
+   * or `null` if there is no target (that is, the target is implicitly `this`)
+   * or if this method invocation is part of a cascade expression.
+   *
+   * Use [realTarget] to get the target independent of whether this is part of a
+   * cascade expression.
+   */
+  Expression get target => _target;
+
+  /**
+   * Set the expression producing the object on which the method is defined to
+   * the given [expression].
+   */
+  void set target(Expression expression) {
+    _target = _becomeParentOf(expression);
+  }
+
+  /**
+   * Return the type arguments to be applied to the method being invoked, or
+   * `null` if no type arguments were provided.
+   */
+  TypeArgumentList get typeArguments => _typeArguments;
+
+  /**
+   * Set the type arguments to be applied to the method being invoked to the
+   * given [typeArguments].
+   */
+  void set typeArguments(TypeArgumentList typeArguments) {
+    _typeArguments = _becomeParentOf(typeArguments);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitMethodInvocation(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_target, visitor);
+    _safelyVisitChild(_methodName, visitor);
+    _safelyVisitChild(_typeArguments, visitor);
+    _safelyVisitChild(_argumentList, visitor);
+  }
+}
+
+/**
+ * A node that declares a single name within the scope of a compilation unit.
+ */
+abstract class NamedCompilationUnitMember extends CompilationUnitMember {
+  /**
+   * The name of the member being declared.
+   */
+  SimpleIdentifier _name;
+
+  /**
+   * Initialize a newly created compilation unit member with the given [name].
+   * Either or both of the [comment] and [metadata] can be `null` if the member
+   * does not have the corresponding attribute.
+   */
+  NamedCompilationUnitMember(
+      Comment comment, List<Annotation> metadata, SimpleIdentifier name)
+      : super(comment, metadata) {
+    _name = _becomeParentOf(name);
+  }
+
+  /**
+   * Return the name of the member being declared.
+   */
+  SimpleIdentifier get name => _name;
+
+  /**
+   * Set the name of the member being declared to the given [identifier].
+   */
+  void set name(SimpleIdentifier identifier) {
+    _name = _becomeParentOf(identifier);
+  }
+}
+
+/**
+ * An expression that has a name associated with it. They are used in method
+ * invocations when there are named parameters.
+ *
+ * > namedExpression ::=
+ * >     [Label] [Expression]
+ */
+class NamedExpression extends Expression {
+  /**
+   * The name associated with the expression.
+   */
+  Label _name;
+
+  /**
+   * The expression with which the name is associated.
+   */
+  Expression _expression;
+
+  /**
+   * Initialize a newly created named expression..
+   */
+  NamedExpression(Label name, Expression expression) {
+    _name = _becomeParentOf(name);
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get beginToken => _name.beginToken;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_name)..add(_expression);
+
+  /**
+   * Return the element representing the parameter being named by this
+   * expression, or `null` if the AST structure has not been resolved or if
+   * there is no parameter with the same name as this expression.
+   */
+  ParameterElement get element {
+    Element element = _name.label.staticElement;
+    if (element is ParameterElement) {
+      return element;
+    }
+    return null;
+  }
+
+  @override
+  Token get endToken => _expression.endToken;
+
+  /**
+   * Return the expression with which the name is associated.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression with which the name is associated to the given
+   * [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  /**
+   * Return the name associated with the expression.
+   */
+  Label get name => _name;
+
+  /**
+   * Set the name associated with the expression to the given [identifier].
+   */
+  void set name(Label identifier) {
+    _name = _becomeParentOf(identifier);
+  }
+
+  @override
+  int get precedence => 0;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitNamedExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_expression, visitor);
+  }
+}
+
+/**
+ * A node that represents a directive that impacts the namespace of a library.
+ *
+ * > directive ::=
+ * >     [ExportDirective]
+ * >   | [ImportDirective]
+ */
+abstract class NamespaceDirective extends UriBasedDirective {
+  /**
+   * The token representing the 'import' or 'export' keyword.
+   */
+  Token keyword;
+
+  /**
+   * The combinators used to control which names are imported or exported.
+   */
+  NodeList<Combinator> _combinators;
+
+  /**
+   * The semicolon terminating the directive.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created namespace directive. Either or both of the
+   * [comment] and [metadata] can be `null` if the directive does not have the
+   * corresponding attribute. The list of [combinators] can be `null` if there
+   * are no combinators.
+   */
+  NamespaceDirective(Comment comment, List<Annotation> metadata, this.keyword,
+      StringLiteral libraryUri, List<Combinator> combinators, this.semicolon)
+      : super(comment, metadata, libraryUri) {
+    _combinators = new NodeList<Combinator>(this, combinators);
+  }
+
+  /**
+   * Return the combinators used to control how names are imported or exported.
+   */
+  NodeList<Combinator> get combinators => _combinators;
+
+  @override
+  Token get endToken => semicolon;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata => keyword;
+
+  @override
+  LibraryElement get uriElement;
+}
+
+/**
+ * The "native" clause in an class declaration.
+ *
+ * > nativeClause ::=
+ * >     'native' [StringLiteral]
+ */
+class NativeClause extends AstNode {
+  /**
+   * The token representing the 'native' keyword.
+   */
+  Token nativeKeyword;
+
+  /**
+   * The name of the native object that implements the class.
+   */
+  StringLiteral _name;
+
+  /**
+   * Initialize a newly created native clause.
+   */
+  NativeClause(this.nativeKeyword, StringLiteral name) {
+    _name = _becomeParentOf(name);
+  }
+
+  @override
+  Token get beginToken => nativeKeyword;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(nativeKeyword)..add(_name);
+
+  @override
+  Token get endToken => _name.endToken;
+
+  /**
+   * Get the token representing the 'native' keyword.
+   */
+  @deprecated // Use "this.nativeKeyword"
+  Token get keyword => nativeKeyword;
+
+  /**
+   * Set the token representing the 'native' keyword to the given [token].
+   */
+  @deprecated // Use "this.nativeKeyword"
+  set keyword(Token token) {
+    nativeKeyword = token;
+  }
+
+  /**
+   * Return the name of the native object that implements the class.
+   */
+  StringLiteral get name => _name;
+
+  /**
+   * Sets the name of the native object that implements the class to the given
+   * [name].
+   */
+  void set name(StringLiteral name) {
+    _name = _becomeParentOf(name);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitNativeClause(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_name, visitor);
+  }
+}
+
+/**
+ * A function body that consists of a native keyword followed by a string
+ * literal.
+ *
+ * > nativeFunctionBody ::=
+ * >     'native' [SimpleStringLiteral] ';'
+ */
+class NativeFunctionBody extends FunctionBody {
+  /**
+   * The token representing 'native' that marks the start of the function body.
+   */
+  Token nativeKeyword;
+
+  /**
+   * The string literal, after the 'native' token.
+   */
+  StringLiteral _stringLiteral;
+
+  /**
+   * The token representing the semicolon that marks the end of the function
+   * body.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created function body consisting of the 'native' token,
+   * a string literal, and a semicolon.
+   */
+  NativeFunctionBody(
+      this.nativeKeyword, StringLiteral stringLiteral, this.semicolon) {
+    _stringLiteral = _becomeParentOf(stringLiteral);
+  }
+
+  @override
+  Token get beginToken => nativeKeyword;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(nativeKeyword)
+    ..add(_stringLiteral)
+    ..add(semicolon);
+
+  @override
+  Token get endToken => semicolon;
+
+  /**
+   * Return the token representing 'native' that marks the start of the function
+   * body.
+   */
+  @deprecated // Use "this.nativeKeyword"
+  Token get nativeToken => nativeKeyword;
+
+  /**
+   * Set the token representing 'native' that marks the start of the function
+   * body to the given [token].
+   */
+  @deprecated // Use "this.nativeKeyword"
+  set nativeToken(Token token) {
+    nativeKeyword = token;
+  }
+
+  /**
+   * Return the string literal representing the string after the 'native' token.
+   */
+  StringLiteral get stringLiteral => _stringLiteral;
+
+  /**
+   * Set the string literal representing the string after the 'native' token to
+   * the given [stringLiteral].
+   */
+  void set stringLiteral(StringLiteral stringLiteral) {
+    _stringLiteral = _becomeParentOf(stringLiteral);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitNativeFunctionBody(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_stringLiteral, visitor);
+  }
+}
+
+/**
+ * A list of AST nodes that have a common parent.
+ */
+class NodeList<E extends AstNode> extends Object with ListMixin<E> {
+  /**
+   * The node that is the parent of each of the elements in the list.
+   */
+  AstNode owner;
+
+  /**
+   * The elements contained in the list.
+   */
+  List<E> _elements = <E>[];
+
+  /**
+   * Initialize a newly created list of nodes such that all of the nodes that
+   * are added to the list will have their parent set to the given [owner]. The
+   * list will initially be populated with the given [elements].
+   */
+  NodeList(this.owner, [List<E> elements]) {
+    addAll(elements);
+  }
+
+  /**
+   * Return the first token included in this node list's source range, or `null`
+   * if the list is empty.
+   */
+  Token get beginToken {
+    if (_elements.length == 0) {
+      return null;
+    }
+    return _elements[0].beginToken;
+  }
+
+  /**
+   * Return the last token included in this node list's source range, or `null`
+   * if the list is empty.
+   */
+  Token get endToken {
+    int length = _elements.length;
+    if (length == 0) {
+      return null;
+    }
+    return _elements[length - 1].endToken;
+  }
+
+  int get length => _elements.length;
+
+  @deprecated // Never intended for public use.
+  void set length(int value) {
+    throw new UnsupportedError("Cannot resize NodeList.");
+  }
+
+  E operator [](int index) {
+    if (index < 0 || index >= _elements.length) {
+      throw new RangeError("Index: $index, Size: ${_elements.length}");
+    }
+    return _elements[index];
+  }
+
+  void operator []=(int index, E node) {
+    if (index < 0 || index >= _elements.length) {
+      throw new RangeError("Index: $index, Size: ${_elements.length}");
+    }
+    owner._becomeParentOf(node);
+    _elements[index] = node;
+  }
+
+  /**
+   * Use the given [visitor] to visit each of the nodes in this list.
+   */
+  accept(AstVisitor visitor) {
+    int length = _elements.length;
+    for (var i = 0; i < length; i++) {
+      _elements[i].accept(visitor);
+    }
+  }
+
+  @override
+  void add(E node) {
+    insert(length, node);
+  }
+
+  @override
+  bool addAll(Iterable<E> nodes) {
+    if (nodes != null && !nodes.isEmpty) {
+      _elements.addAll(nodes);
+      for (E node in nodes) {
+        owner._becomeParentOf(node);
+      }
+      return true;
+    }
+    return false;
+  }
+
+  @override
+  void clear() {
+    _elements = <E>[];
+  }
+
+  @override
+  void insert(int index, E node) {
+    int length = _elements.length;
+    if (index < 0 || index > length) {
+      throw new RangeError("Index: $index, Size: ${_elements.length}");
+    }
+    owner._becomeParentOf(node);
+    if (length == 0) {
+      _elements.add(node);
+    } else {
+      _elements.insert(index, node);
+    }
+  }
+
+  @override
+  E removeAt(int index) {
+    if (index < 0 || index >= _elements.length) {
+      throw new RangeError("Index: $index, Size: ${_elements.length}");
+    }
+    E removedNode = _elements[index];
+    _elements.removeAt(index);
+    return removedNode;
+  }
+
+  /**
+   * Create an empty list with the given [owner].
+   */
+  @deprecated // Use "new NodeList<E>(owner)"
+  static NodeList create(AstNode owner) => new NodeList(owner);
+}
+
+/**
+ * An object used to locate the [AstNode] associated with a source range, given
+ * the AST structure built from the source. More specifically, they will return
+ * the [AstNode] with the shortest length whose source range completely
+ * encompasses the specified range.
+ */
+class NodeLocator extends UnifyingAstVisitor<Object> {
+  /**
+   * The start offset of the range used to identify the node.
+   */
+  int _startOffset = 0;
+
+  /**
+   * The end offset of the range used to identify the node.
+   */
+  int _endOffset = 0;
+
+  /**
+   * The element that was found that corresponds to the given source range, or
+   * `null` if there is no such element.
+   */
+  AstNode _foundNode;
+
+  /**
+   * Initialize a newly created locator to locate an [AstNode] by locating the
+   * node within an AST structure that corresponds to the given range of
+   * characters (between the [startOffset] and [endOffset] in the source.
+   */
+  NodeLocator(int startOffset, [int endOffset])
+      : this._startOffset = startOffset,
+        this._endOffset = endOffset == null ? startOffset : endOffset;
+
+  /**
+   * Initialize a newly created locator to locate an [AstNode] by locating the
+   * node within an AST structure that corresponds to the given [offset] in the
+   * source.
+   */
+  @deprecated // Use new NodeLocator(offset)
+  NodeLocator.con1(int offset) : this(offset);
+
+  /**
+   * Initialize a newly created locator to locate an [AstNode] by locating the
+   * node within an AST structure that corresponds to the given range of
+   * characters (between the [startOffset] and [endOffset] in the source.
+   */
+  @deprecated // Use new NodeLocator(startOffset, endOffset)
+  NodeLocator.con2(this._startOffset, this._endOffset);
+
+  /**
+   * Return the node that was found that corresponds to the given source range
+   * or `null` if there is no such node.
+   */
+  AstNode get foundNode => _foundNode;
+
+  /**
+   * Search within the given AST [node] for an identifier representing an
+   * element in the specified source range. Return the element that was found,
+   * or `null` if no element was found.
+   */
+  AstNode searchWithin(AstNode node) {
+    if (node == null) {
+      return null;
+    }
+    try {
+      node.accept(this);
+    } on NodeLocator_NodeFoundException {
+      // A node with the right source position was found.
+    } catch (exception, stackTrace) {
+      AnalysisEngine.instance.logger.logInformation(
+          "Unable to locate element at offset ($_startOffset - $_endOffset)",
+          new CaughtException(exception, stackTrace));
+      return null;
+    }
+    return _foundNode;
+  }
+
+  @override
+  Object visitNode(AstNode node) {
+    Token beginToken = node.beginToken;
+    Token endToken = node.endToken;
+    // Don't include synthetic tokens.
+    while (endToken != beginToken) {
+      if (endToken.type == TokenType.EOF || !endToken.isSynthetic) {
+        break;
+      }
+      endToken = endToken.previous;
+    }
+    int end = endToken.end;
+    int start = node.offset;
+    if (end < _startOffset) {
+      return null;
+    }
+    if (start > _endOffset) {
+      return null;
+    }
+    try {
+      node.visitChildren(this);
+    } on NodeLocator_NodeFoundException {
+      rethrow;
+    } catch (exception, stackTrace) {
+      // Ignore the exception and proceed in order to visit the rest of the
+      // structure.
+      AnalysisEngine.instance.logger.logInformation(
+          "Exception caught while traversing an AST structure.",
+          new CaughtException(exception, stackTrace));
+    }
+    if (start <= _startOffset && _endOffset <= end) {
+      _foundNode = node;
+      throw new NodeLocator_NodeFoundException();
+    }
+    return null;
+  }
+}
+
+/**
+ * An exception used by [NodeLocator] to cancel visiting after a node has been
+ * found.
+ */
+class NodeLocator_NodeFoundException extends RuntimeException {}
+
+/**
+ * An object that will replace one child node in an AST node with another node.
+ */
+class NodeReplacer implements AstVisitor<bool> {
+  /**
+   * The node being replaced.
+   */
+  final AstNode _oldNode;
+
+  /**
+   * The node that is replacing the old node.
+   */
+  final AstNode _newNode;
+
+  /**
+   * Initialize a newly created node locator to replace the [_oldNode] with the
+   * [_newNode].
+   */
+  NodeReplacer(this._oldNode, this._newNode);
+
+  @override
+  bool visitAdjacentStrings(AdjacentStrings node) {
+    if (_replaceInList(node.strings)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  bool visitAnnotatedNode(AnnotatedNode node) {
+    if (identical(node.documentationComment, _oldNode)) {
+      node.documentationComment = _newNode as Comment;
+      return true;
+    } else if (_replaceInList(node.metadata)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitAnnotation(Annotation node) {
+    if (identical(node.arguments, _oldNode)) {
+      node.arguments = _newNode as ArgumentList;
+      return true;
+    } else if (identical(node.constructorName, _oldNode)) {
+      node.constructorName = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.name, _oldNode)) {
+      node.name = _newNode as Identifier;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitArgumentList(ArgumentList node) {
+    if (_replaceInList(node.arguments)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitAsExpression(AsExpression node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    } else if (identical(node.type, _oldNode)) {
+      node.type = _newNode as TypeName;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitAssertStatement(AssertStatement node) {
+    if (identical(node.condition, _oldNode)) {
+      node.condition = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitAssignmentExpression(AssignmentExpression node) {
+    if (identical(node.leftHandSide, _oldNode)) {
+      node.leftHandSide = _newNode as Expression;
+      return true;
+    } else if (identical(node.rightHandSide, _oldNode)) {
+      node.rightHandSide = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitAwaitExpression(AwaitExpression node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitBinaryExpression(BinaryExpression node) {
+    if (identical(node.leftOperand, _oldNode)) {
+      node.leftOperand = _newNode as Expression;
+      return true;
+    } else if (identical(node.rightOperand, _oldNode)) {
+      node.rightOperand = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitBlock(Block node) {
+    if (_replaceInList(node.statements)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitBlockFunctionBody(BlockFunctionBody node) {
+    if (identical(node.block, _oldNode)) {
+      node.block = _newNode as Block;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitBooleanLiteral(BooleanLiteral node) => visitNode(node);
+
+  @override
+  bool visitBreakStatement(BreakStatement node) {
+    if (identical(node.label, _oldNode)) {
+      node.label = _newNode as SimpleIdentifier;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitCascadeExpression(CascadeExpression node) {
+    if (identical(node.target, _oldNode)) {
+      node.target = _newNode as Expression;
+      return true;
+    } else if (_replaceInList(node.cascadeSections)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitCatchClause(CatchClause node) {
+    if (identical(node.exceptionType, _oldNode)) {
+      node.exceptionType = _newNode as TypeName;
+      return true;
+    } else if (identical(node.exceptionParameter, _oldNode)) {
+      node.exceptionParameter = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.stackTraceParameter, _oldNode)) {
+      node.stackTraceParameter = _newNode as SimpleIdentifier;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitClassDeclaration(ClassDeclaration node) {
+    if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.typeParameters, _oldNode)) {
+      node.typeParameters = _newNode as TypeParameterList;
+      return true;
+    } else if (identical(node.extendsClause, _oldNode)) {
+      node.extendsClause = _newNode as ExtendsClause;
+      return true;
+    } else if (identical(node.withClause, _oldNode)) {
+      node.withClause = _newNode as WithClause;
+      return true;
+    } else if (identical(node.implementsClause, _oldNode)) {
+      node.implementsClause = _newNode as ImplementsClause;
+      return true;
+    } else if (identical(node.nativeClause, _oldNode)) {
+      node.nativeClause = _newNode as NativeClause;
+      return true;
+    } else if (_replaceInList(node.members)) {
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitClassTypeAlias(ClassTypeAlias node) {
+    if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.typeParameters, _oldNode)) {
+      node.typeParameters = _newNode as TypeParameterList;
+      return true;
+    } else if (identical(node.superclass, _oldNode)) {
+      node.superclass = _newNode as TypeName;
+      return true;
+    } else if (identical(node.withClause, _oldNode)) {
+      node.withClause = _newNode as WithClause;
+      return true;
+    } else if (identical(node.implementsClause, _oldNode)) {
+      node.implementsClause = _newNode as ImplementsClause;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitComment(Comment node) {
+    if (_replaceInList(node.references)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitCommentReference(CommentReference node) {
+    if (identical(node.identifier, _oldNode)) {
+      node.identifier = _newNode as Identifier;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitCompilationUnit(CompilationUnit node) {
+    if (identical(node.scriptTag, _oldNode)) {
+      node.scriptTag = _newNode as ScriptTag;
+      return true;
+    } else if (_replaceInList(node.directives)) {
+      return true;
+    } else if (_replaceInList(node.declarations)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitConditionalExpression(ConditionalExpression node) {
+    if (identical(node.condition, _oldNode)) {
+      node.condition = _newNode as Expression;
+      return true;
+    } else if (identical(node.thenExpression, _oldNode)) {
+      node.thenExpression = _newNode as Expression;
+      return true;
+    } else if (identical(node.elseExpression, _oldNode)) {
+      node.elseExpression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitConstructorDeclaration(ConstructorDeclaration node) {
+    if (identical(node.returnType, _oldNode)) {
+      node.returnType = _newNode as Identifier;
+      return true;
+    } else if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.parameters, _oldNode)) {
+      node.parameters = _newNode as FormalParameterList;
+      return true;
+    } else if (identical(node.redirectedConstructor, _oldNode)) {
+      node.redirectedConstructor = _newNode as ConstructorName;
+      return true;
+    } else if (identical(node.body, _oldNode)) {
+      node.body = _newNode as FunctionBody;
+      return true;
+    } else if (_replaceInList(node.initializers)) {
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
+    if (identical(node.fieldName, _oldNode)) {
+      node.fieldName = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitConstructorName(ConstructorName node) {
+    if (identical(node.type, _oldNode)) {
+      node.type = _newNode as TypeName;
+      return true;
+    } else if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitContinueStatement(ContinueStatement node) {
+    if (identical(node.label, _oldNode)) {
+      node.label = _newNode as SimpleIdentifier;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitDeclaredIdentifier(DeclaredIdentifier node) {
+    if (identical(node.type, _oldNode)) {
+      node.type = _newNode as TypeName;
+      return true;
+    } else if (identical(node.identifier, _oldNode)) {
+      node.identifier = _newNode as SimpleIdentifier;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitDefaultFormalParameter(DefaultFormalParameter node) {
+    if (identical(node.parameter, _oldNode)) {
+      node.parameter = _newNode as NormalFormalParameter;
+      return true;
+    } else if (identical(node.defaultValue, _oldNode)) {
+      node.defaultValue = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitDoStatement(DoStatement node) {
+    if (identical(node.body, _oldNode)) {
+      node.body = _newNode as Statement;
+      return true;
+    } else if (identical(node.condition, _oldNode)) {
+      node.condition = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitDoubleLiteral(DoubleLiteral node) => visitNode(node);
+
+  @override
+  bool visitEmptyFunctionBody(EmptyFunctionBody node) => visitNode(node);
+
+  @override
+  bool visitEmptyStatement(EmptyStatement node) => visitNode(node);
+
+  @override
+  bool visitEnumConstantDeclaration(EnumConstantDeclaration node) {
+    if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitEnumDeclaration(EnumDeclaration node) {
+    if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    } else if (_replaceInList(node.constants)) {
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitExportDirective(ExportDirective node) =>
+      visitNamespaceDirective(node);
+
+  @override
+  bool visitExpressionFunctionBody(ExpressionFunctionBody node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitExpressionStatement(ExpressionStatement node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitExtendsClause(ExtendsClause node) {
+    if (identical(node.superclass, _oldNode)) {
+      node.superclass = _newNode as TypeName;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitFieldDeclaration(FieldDeclaration node) {
+    if (identical(node.fields, _oldNode)) {
+      node.fields = _newNode as VariableDeclarationList;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitFieldFormalParameter(FieldFormalParameter node) {
+    if (identical(node.type, _oldNode)) {
+      node.type = _newNode as TypeName;
+      return true;
+    } else if (identical(node.parameters, _oldNode)) {
+      node.parameters = _newNode as FormalParameterList;
+      return true;
+    }
+    return visitNormalFormalParameter(node);
+  }
+
+  @override
+  bool visitForEachStatement(ForEachStatement node) {
+    if (identical(node.loopVariable, _oldNode)) {
+      node.loopVariable = _newNode as DeclaredIdentifier;
+      return true;
+    } else if (identical(node.identifier, _oldNode)) {
+      node.identifier = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.iterable, _oldNode)) {
+      node.iterable = _newNode as Expression;
+      return true;
+    } else if (identical(node.body, _oldNode)) {
+      node.body = _newNode as Statement;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitFormalParameterList(FormalParameterList node) {
+    if (_replaceInList(node.parameters)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitForStatement(ForStatement node) {
+    if (identical(node.variables, _oldNode)) {
+      node.variables = _newNode as VariableDeclarationList;
+      return true;
+    } else if (identical(node.initialization, _oldNode)) {
+      node.initialization = _newNode as Expression;
+      return true;
+    } else if (identical(node.condition, _oldNode)) {
+      node.condition = _newNode as Expression;
+      return true;
+    } else if (identical(node.body, _oldNode)) {
+      node.body = _newNode as Statement;
+      return true;
+    } else if (_replaceInList(node.updaters)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitFunctionDeclaration(FunctionDeclaration node) {
+    if (identical(node.returnType, _oldNode)) {
+      node.returnType = _newNode as TypeName;
+      return true;
+    } else if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.functionExpression, _oldNode)) {
+      node.functionExpression = _newNode as FunctionExpression;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitFunctionDeclarationStatement(FunctionDeclarationStatement node) {
+    if (identical(node.functionDeclaration, _oldNode)) {
+      node.functionDeclaration = _newNode as FunctionDeclaration;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitFunctionExpression(FunctionExpression node) {
+    if (identical(node.parameters, _oldNode)) {
+      node.parameters = _newNode as FormalParameterList;
+      return true;
+    } else if (identical(node.body, _oldNode)) {
+      node.body = _newNode as FunctionBody;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitFunctionExpressionInvocation(FunctionExpressionInvocation node) {
+    if (identical(node.function, _oldNode)) {
+      node.function = _newNode as Expression;
+      return true;
+    } else if (identical(node.argumentList, _oldNode)) {
+      node.argumentList = _newNode as ArgumentList;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitFunctionTypeAlias(FunctionTypeAlias node) {
+    if (identical(node.returnType, _oldNode)) {
+      node.returnType = _newNode as TypeName;
+      return true;
+    } else if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.typeParameters, _oldNode)) {
+      node.typeParameters = _newNode as TypeParameterList;
+      return true;
+    } else if (identical(node.parameters, _oldNode)) {
+      node.parameters = _newNode as FormalParameterList;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
+    if (identical(node.returnType, _oldNode)) {
+      node.returnType = _newNode as TypeName;
+      return true;
+    } else if (identical(node.parameters, _oldNode)) {
+      node.parameters = _newNode as FormalParameterList;
+      return true;
+    }
+    return visitNormalFormalParameter(node);
+  }
+
+  @override
+  bool visitHideCombinator(HideCombinator node) {
+    if (_replaceInList(node.hiddenNames)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitIfStatement(IfStatement node) {
+    if (identical(node.condition, _oldNode)) {
+      node.condition = _newNode as Expression;
+      return true;
+    } else if (identical(node.thenStatement, _oldNode)) {
+      node.thenStatement = _newNode as Statement;
+      return true;
+    } else if (identical(node.elseStatement, _oldNode)) {
+      node.elseStatement = _newNode as Statement;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitImplementsClause(ImplementsClause node) {
+    if (_replaceInList(node.interfaces)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitImportDirective(ImportDirective node) {
+    if (identical(node.prefix, _oldNode)) {
+      node.prefix = _newNode as SimpleIdentifier;
+      return true;
+    }
+    return visitNamespaceDirective(node);
+  }
+
+  @override
+  bool visitIndexExpression(IndexExpression node) {
+    if (identical(node.target, _oldNode)) {
+      node.target = _newNode as Expression;
+      return true;
+    } else if (identical(node.index, _oldNode)) {
+      node.index = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitInstanceCreationExpression(InstanceCreationExpression node) {
+    if (identical(node.constructorName, _oldNode)) {
+      node.constructorName = _newNode as ConstructorName;
+      return true;
+    } else if (identical(node.argumentList, _oldNode)) {
+      node.argumentList = _newNode as ArgumentList;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitIntegerLiteral(IntegerLiteral node) => visitNode(node);
+
+  @override
+  bool visitInterpolationExpression(InterpolationExpression node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitInterpolationString(InterpolationString node) => visitNode(node);
+
+  @override
+  bool visitIsExpression(IsExpression node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    } else if (identical(node.type, _oldNode)) {
+      node.type = _newNode as TypeName;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitLabel(Label node) {
+    if (identical(node.label, _oldNode)) {
+      node.label = _newNode as SimpleIdentifier;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitLabeledStatement(LabeledStatement node) {
+    if (identical(node.statement, _oldNode)) {
+      node.statement = _newNode as Statement;
+      return true;
+    } else if (_replaceInList(node.labels)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitLibraryDirective(LibraryDirective node) {
+    if (identical(node.name, _oldNode)) {
+      node.name = _newNode as LibraryIdentifier;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitLibraryIdentifier(LibraryIdentifier node) {
+    if (_replaceInList(node.components)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitListLiteral(ListLiteral node) {
+    if (_replaceInList(node.elements)) {
+      return true;
+    }
+    return visitTypedLiteral(node);
+  }
+
+  @override
+  bool visitMapLiteral(MapLiteral node) {
+    if (_replaceInList(node.entries)) {
+      return true;
+    }
+    return visitTypedLiteral(node);
+  }
+
+  @override
+  bool visitMapLiteralEntry(MapLiteralEntry node) {
+    if (identical(node.key, _oldNode)) {
+      node.key = _newNode as Expression;
+      return true;
+    } else if (identical(node.value, _oldNode)) {
+      node.value = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitMethodDeclaration(MethodDeclaration node) {
+    if (identical(node.returnType, _oldNode)) {
+      node.returnType = _newNode as TypeName;
+      return true;
+    } else if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.parameters, _oldNode)) {
+      node.parameters = _newNode as FormalParameterList;
+      return true;
+    } else if (identical(node.body, _oldNode)) {
+      node.body = _newNode as FunctionBody;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitMethodInvocation(MethodInvocation node) {
+    if (identical(node.target, _oldNode)) {
+      node.target = _newNode as Expression;
+      return true;
+    } else if (identical(node.methodName, _oldNode)) {
+      node.methodName = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.argumentList, _oldNode)) {
+      node.argumentList = _newNode as ArgumentList;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitNamedExpression(NamedExpression node) {
+    if (identical(node.name, _oldNode)) {
+      node.name = _newNode as Label;
+      return true;
+    } else if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  bool visitNamespaceDirective(NamespaceDirective node) {
+    if (_replaceInList(node.combinators)) {
+      return true;
+    }
+    return visitUriBasedDirective(node);
+  }
+
+  @override
+  bool visitNativeClause(NativeClause node) {
+    if (identical(node.name, _oldNode)) {
+      node.name = _newNode as StringLiteral;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitNativeFunctionBody(NativeFunctionBody node) {
+    if (identical(node.stringLiteral, _oldNode)) {
+      node.stringLiteral = _newNode as StringLiteral;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  bool visitNode(AstNode node) {
+    throw new IllegalArgumentException(
+        "The old node is not a child of it's parent");
+  }
+
+  bool visitNormalFormalParameter(NormalFormalParameter node) {
+    if (identical(node.documentationComment, _oldNode)) {
+      node.documentationComment = _newNode as Comment;
+      return true;
+    } else if (identical(node.identifier, _oldNode)) {
+      node.identifier = _newNode as SimpleIdentifier;
+      return true;
+    } else if (_replaceInList(node.metadata)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitNullLiteral(NullLiteral node) => visitNode(node);
+
+  @override
+  bool visitParenthesizedExpression(ParenthesizedExpression node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitPartDirective(PartDirective node) => visitUriBasedDirective(node);
+
+  @override
+  bool visitPartOfDirective(PartOfDirective node) {
+    if (identical(node.libraryName, _oldNode)) {
+      node.libraryName = _newNode as LibraryIdentifier;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitPostfixExpression(PostfixExpression node) {
+    if (identical(node.operand, _oldNode)) {
+      node.operand = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitPrefixedIdentifier(PrefixedIdentifier node) {
+    if (identical(node.prefix, _oldNode)) {
+      node.prefix = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.identifier, _oldNode)) {
+      node.identifier = _newNode as SimpleIdentifier;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitPrefixExpression(PrefixExpression node) {
+    if (identical(node.operand, _oldNode)) {
+      node.operand = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitPropertyAccess(PropertyAccess node) {
+    if (identical(node.target, _oldNode)) {
+      node.target = _newNode as Expression;
+      return true;
+    } else if (identical(node.propertyName, _oldNode)) {
+      node.propertyName = _newNode as SimpleIdentifier;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) {
+    if (identical(node.constructorName, _oldNode)) {
+      node.constructorName = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.argumentList, _oldNode)) {
+      node.argumentList = _newNode as ArgumentList;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitRethrowExpression(RethrowExpression node) => visitNode(node);
+
+  @override
+  bool visitReturnStatement(ReturnStatement node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitScriptTag(ScriptTag scriptTag) => visitNode(scriptTag);
+
+  @override
+  bool visitShowCombinator(ShowCombinator node) {
+    if (_replaceInList(node.shownNames)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitSimpleFormalParameter(SimpleFormalParameter node) {
+    if (identical(node.type, _oldNode)) {
+      node.type = _newNode as TypeName;
+      return true;
+    }
+    return visitNormalFormalParameter(node);
+  }
+
+  @override
+  bool visitSimpleIdentifier(SimpleIdentifier node) => visitNode(node);
+
+  @override
+  bool visitSimpleStringLiteral(SimpleStringLiteral node) => visitNode(node);
+
+  @override
+  bool visitStringInterpolation(StringInterpolation node) {
+    if (_replaceInList(node.elements)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitSuperConstructorInvocation(SuperConstructorInvocation node) {
+    if (identical(node.constructorName, _oldNode)) {
+      node.constructorName = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.argumentList, _oldNode)) {
+      node.argumentList = _newNode as ArgumentList;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitSuperExpression(SuperExpression node) => visitNode(node);
+
+  @override
+  bool visitSwitchCase(SwitchCase node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitSwitchMember(node);
+  }
+
+  @override
+  bool visitSwitchDefault(SwitchDefault node) => visitSwitchMember(node);
+
+  bool visitSwitchMember(SwitchMember node) {
+    if (_replaceInList(node.labels)) {
+      return true;
+    } else if (_replaceInList(node.statements)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitSwitchStatement(SwitchStatement node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    } else if (_replaceInList(node.members)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitSymbolLiteral(SymbolLiteral node) => visitNode(node);
+
+  @override
+  bool visitThisExpression(ThisExpression node) => visitNode(node);
+
+  @override
+  bool visitThrowExpression(ThrowExpression node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
+    if (identical(node.variables, _oldNode)) {
+      node.variables = _newNode as VariableDeclarationList;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitTryStatement(TryStatement node) {
+    if (identical(node.body, _oldNode)) {
+      node.body = _newNode as Block;
+      return true;
+    } else if (identical(node.finallyBlock, _oldNode)) {
+      node.finallyBlock = _newNode as Block;
+      return true;
+    } else if (_replaceInList(node.catchClauses)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitTypeArgumentList(TypeArgumentList node) {
+    if (_replaceInList(node.arguments)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  bool visitTypedLiteral(TypedLiteral node) {
+    if (identical(node.typeArguments, _oldNode)) {
+      node.typeArguments = _newNode as TypeArgumentList;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitTypeName(TypeName node) {
+    if (identical(node.name, _oldNode)) {
+      node.name = _newNode as Identifier;
+      return true;
+    } else if (identical(node.typeArguments, _oldNode)) {
+      node.typeArguments = _newNode as TypeArgumentList;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitTypeParameter(TypeParameter node) {
+    if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.bound, _oldNode)) {
+      node.bound = _newNode as TypeName;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitTypeParameterList(TypeParameterList node) {
+    if (_replaceInList(node.typeParameters)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  bool visitUriBasedDirective(UriBasedDirective node) {
+    if (identical(node.uri, _oldNode)) {
+      node.uri = _newNode as StringLiteral;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitVariableDeclaration(VariableDeclaration node) {
+    if (identical(node.name, _oldNode)) {
+      node.name = _newNode as SimpleIdentifier;
+      return true;
+    } else if (identical(node.initializer, _oldNode)) {
+      node.initializer = _newNode as Expression;
+      return true;
+    }
+    return visitAnnotatedNode(node);
+  }
+
+  @override
+  bool visitVariableDeclarationList(VariableDeclarationList node) {
+    if (identical(node.type, _oldNode)) {
+      node.type = _newNode as TypeName;
+      return true;
+    } else if (_replaceInList(node.variables)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitVariableDeclarationStatement(VariableDeclarationStatement node) {
+    if (identical(node.variables, _oldNode)) {
+      node.variables = _newNode as VariableDeclarationList;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitWhileStatement(WhileStatement node) {
+    if (identical(node.condition, _oldNode)) {
+      node.condition = _newNode as Expression;
+      return true;
+    } else if (identical(node.body, _oldNode)) {
+      node.body = _newNode as Statement;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitWithClause(WithClause node) {
+    if (_replaceInList(node.mixinTypes)) {
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  @override
+  bool visitYieldStatement(YieldStatement node) {
+    if (identical(node.expression, _oldNode)) {
+      node.expression = _newNode as Expression;
+      return true;
+    }
+    return visitNode(node);
+  }
+
+  bool _replaceInList(NodeList list) {
+    int count = list.length;
+    for (int i = 0; i < count; i++) {
+      if (identical(_oldNode, list[i])) {
+        list[i] = _newNode;
+        return true;
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Replace the [oldNode] with the [newNode] in the AST structure containing
+   * the old node. Return `true` if the replacement was successful.
+   *
+   * Throws an [IllegalArgumentException] if either node is `null`, if the old
+   * node does not have a parent node, or if the AST structure has been
+   * corrupted.
+   */
+  static bool replace(AstNode oldNode, AstNode newNode) {
+    if (oldNode == null || newNode == null) {
+      throw new IllegalArgumentException(
+          "The old and new nodes must be non-null");
+    } else if (identical(oldNode, newNode)) {
+      return true;
+    }
+    AstNode parent = oldNode.parent;
+    if (parent == null) {
+      throw new IllegalArgumentException(
+          "The old node is not a child of another node");
+    }
+    NodeReplacer replacer = new NodeReplacer(oldNode, newNode);
+    return parent.accept(replacer);
+  }
+}
+
+/**
+ * A formal parameter that is required (is not optional).
+ *
+ * > normalFormalParameter ::=
+ * >     [FunctionTypedFormalParameter]
+ * >   | [FieldFormalParameter]
+ * >   | [SimpleFormalParameter]
+ */
+abstract class NormalFormalParameter extends FormalParameter {
+  /**
+   * The documentation comment associated with this parameter, or `null` if this
+   * parameter does not have a documentation comment associated with it.
+   */
+  Comment _comment;
+
+  /**
+   * The annotations associated with this parameter.
+   */
+  NodeList<Annotation> _metadata;
+
+  /**
+   * The name of the parameter being declared.
+   */
+  SimpleIdentifier _identifier;
+
+  /**
+   * Initialize a newly created formal parameter. Either or both of the
+   * [comment] and [metadata] can be `null` if the parameter does not have the
+   * corresponding attribute.
+   */
+  NormalFormalParameter(
+      Comment comment, List<Annotation> metadata, SimpleIdentifier identifier) {
+    _comment = _becomeParentOf(comment);
+    _metadata = new NodeList<Annotation>(this, metadata);
+    _identifier = _becomeParentOf(identifier);
+  }
+
+  /**
+   * Return the documentation comment associated with this parameter, or `null`
+   * if this parameter does not have a documentation comment associated with it.
+   */
+  Comment get documentationComment => _comment;
+
+  /**
+   * Set the documentation comment associated with this parameter to the given
+   * [comment].
+   */
+  void set documentationComment(Comment comment) {
+    _comment = _becomeParentOf(comment);
+  }
+
+  @override
+  SimpleIdentifier get identifier => _identifier;
+
+  /**
+   * Set the name of the parameter being declared to the given [identifier].
+   */
+  void set identifier(SimpleIdentifier identifier) {
+    _identifier = _becomeParentOf(identifier);
+  }
+
+  @override
+  ParameterKind get kind {
+    AstNode parent = this.parent;
+    if (parent is DefaultFormalParameter) {
+      return parent.kind;
+    }
+    return ParameterKind.REQUIRED;
+  }
+
+  @override
+  NodeList<Annotation> get metadata => _metadata;
+
+  /**
+   * Set the metadata associated with this node to the given [metadata].
+   */
+  void set metadata(List<Annotation> metadata) {
+    _metadata.clear();
+    _metadata.addAll(metadata);
+  }
+
+  /**
+   * Return a list containing the comment and annotations associated with this
+   * parameter, sorted in lexical order.
+   */
+  List<AstNode> get sortedCommentAndAnnotations {
+    return <AstNode>[]
+      ..add(_comment)
+      ..addAll(_metadata)
+      ..sort(AstNode.LEXICAL_ORDER);
+  }
+
+  ChildEntities get _childEntities {
+    ChildEntities result = new ChildEntities();
+    if (_commentIsBeforeAnnotations()) {
+      result
+        ..add(_comment)
+        ..addAll(_metadata);
+    } else {
+      result.addAll(sortedCommentAndAnnotations);
+    }
+    return result;
+  }
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    //
+    // Note that subclasses are responsible for visiting the identifier because
+    // they often need to visit other nodes before visiting the identifier.
+    //
+    if (_commentIsBeforeAnnotations()) {
+      _safelyVisitChild(_comment, visitor);
+      _metadata.accept(visitor);
+    } else {
+      for (AstNode child in sortedCommentAndAnnotations) {
+        child.accept(visitor);
+      }
+    }
+  }
+
+  /**
+   * Return `true` if the comment is lexically before any annotations.
+   */
+  bool _commentIsBeforeAnnotations() {
+    if (_comment == null || _metadata.isEmpty) {
+      return true;
+    }
+    Annotation firstAnnotation = _metadata[0];
+    return _comment.offset < firstAnnotation.offset;
+  }
+}
+
+/**
+ * A null literal expression.
+ *
+ * > nullLiteral ::=
+ * >     'null'
+ */
+class NullLiteral extends Literal {
+  /**
+   * The token representing the literal.
+   */
+  Token literal;
+
+  /**
+   * Initialize a newly created null literal.
+   */
+  NullLiteral(this.literal);
+
+  @override
+  Token get beginToken => literal;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(literal);
+
+  @override
+  Token get endToken => literal;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitNullLiteral(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+}
+
+/**
+ * A parenthesized expression.
+ *
+ * > parenthesizedExpression ::=
+ * >     '(' [Expression] ')'
+ */
+class ParenthesizedExpression extends Expression {
+  /**
+   * The left parenthesis.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The expression within the parentheses.
+   */
+  Expression _expression;
+
+  /**
+   * The right parenthesis.
+   */
+  Token rightParenthesis;
+
+  /**
+   * Initialize a newly created parenthesized expression.
+   */
+  ParenthesizedExpression(
+      this.leftParenthesis, Expression expression, this.rightParenthesis) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get beginToken => leftParenthesis;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(leftParenthesis)
+    ..add(_expression)
+    ..add(rightParenthesis);
+
+  @override
+  Token get endToken => rightParenthesis;
+
+  /**
+   * Return the expression within the parentheses.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression within the parentheses to the given [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  int get precedence => 15;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitParenthesizedExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+  }
+}
+
+/**
+ * A part directive.
+ *
+ * > partDirective ::=
+ * >     [Annotation] 'part' [StringLiteral] ';'
+ */
+class PartDirective extends UriBasedDirective {
+  /**
+   * The token representing the 'part' keyword.
+   */
+  Token partKeyword;
+
+  /**
+   * The semicolon terminating the directive.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created part directive. Either or both of the [comment]
+   * and [metadata] can be `null` if the directive does not have the
+   * corresponding attribute.
+   */
+  PartDirective(Comment comment, List<Annotation> metadata, this.partKeyword,
+      StringLiteral partUri, this.semicolon)
+      : super(comment, metadata, partUri);
+
+  @override
+  Iterable get childEntities =>
+      super._childEntities..add(partKeyword)..add(_uri)..add(semicolon);
+
+  @override
+  Token get endToken => semicolon;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata => partKeyword;
+
+  @override
+  Token get keyword => partKeyword;
+
+  /**
+   * Return the token representing the 'part' token.
+   */
+  @deprecated // Use "this.partKeyword"
+  Token get partToken => partKeyword;
+
+  /**
+   * Set the token representing the 'part' token to the given [token].
+   */
+  @deprecated // Use "this.partKeyword"
+  set partToken(Token token) {
+    partKeyword = token;
+  }
+
+  @override
+  CompilationUnitElement get uriElement => element as CompilationUnitElement;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitPartDirective(this);
+}
+
+/**
+ * A part-of directive.
+ *
+ * > partOfDirective ::=
+ * >     [Annotation] 'part' 'of' [Identifier] ';'
+ */
+class PartOfDirective extends Directive {
+  /**
+   * The token representing the 'part' keyword.
+   */
+  Token partKeyword;
+
+  /**
+   * The token representing the 'of' keyword.
+   */
+  Token ofKeyword;
+
+  /**
+   * The name of the library that the containing compilation unit is part of.
+   */
+  LibraryIdentifier _libraryName;
+
+  /**
+   * The semicolon terminating the directive.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created part-of directive. Either or both of the
+   * [comment] and [metadata] can be `null` if the directive does not have the
+   * corresponding attribute.
+   */
+  PartOfDirective(Comment comment, List<Annotation> metadata, this.partKeyword,
+      this.ofKeyword, LibraryIdentifier libraryName, this.semicolon)
+      : super(comment, metadata) {
+    _libraryName = _becomeParentOf(libraryName);
+  }
+
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(partKeyword)
+    ..add(ofKeyword)
+    ..add(_libraryName)
+    ..add(semicolon);
+
+  @override
+  Token get endToken => semicolon;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata => partKeyword;
+
+  @override
+  Token get keyword => partKeyword;
+
+  /**
+   * Return the name of the library that the containing compilation unit is part
+   * of.
+   */
+  LibraryIdentifier get libraryName => _libraryName;
+
+  /**
+   * Set the name of the library that the containing compilation unit is part of
+   * to the given [libraryName].
+   */
+  void set libraryName(LibraryIdentifier libraryName) {
+    _libraryName = _becomeParentOf(libraryName);
+  }
+
+  /**
+   * Return the token representing the 'of' token.
+   */
+  @deprecated // Use "this.ofKeyword"
+  Token get ofToken => ofKeyword;
+
+  /**
+   * Set the token representing the 'of' token to the given [token].
+   */
+  @deprecated // Use "this.ofKeyword"
+  set ofToken(Token token) {
+    ofKeyword = token;
+  }
+
+  /**
+   * Return the token representing the 'part' token.
+   */
+  @deprecated // Use "this.partKeyword"
+  Token get partToken => partKeyword;
+
+  /**
+   * Set the token representing the 'part' token to the given [token].
+   */
+  @deprecated // Use "this.partKeyword"
+  set partToken(Token token) {
+    partKeyword = token;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitPartOfDirective(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_libraryName, visitor);
+  }
+}
+
+/**
+ * A postfix unary expression.
+ *
+ * > postfixExpression ::=
+ * >     [Expression] [Token]
+ */
+class PostfixExpression extends Expression {
+  /**
+   * The expression computing the operand for the operator.
+   */
+  Expression _operand;
+
+  /**
+   * The postfix operator being applied to the operand.
+   */
+  Token operator;
+
+  /**
+   * The element associated with this the operator based on the propagated type
+   * of the operand, or `null` if the AST structure has not been resolved, if
+   * the operator is not user definable, or if the operator could not be
+   * resolved.
+   */
+  MethodElement propagatedElement;
+
+  /**
+   * The element associated with the operator based on the static type of the
+   * operand, or `null` if the AST structure has not been resolved, if the
+   * operator is not user definable, or if the operator could not be resolved.
+   */
+  MethodElement staticElement;
+
+  /**
+   * Initialize a newly created postfix expression.
+   */
+  PostfixExpression(Expression operand, this.operator) {
+    _operand = _becomeParentOf(operand);
+  }
+
+  @override
+  Token get beginToken => _operand.beginToken;
+
+  /**
+   * Return the best element available for this operator. If resolution was able
+   * to find a better element based on type propagation, that element will be
+   * returned. Otherwise, the element found using the result of static analysis
+   * will be returned. If resolution has not been performed, then `null` will be
+   * returned.
+   */
+  MethodElement get bestElement {
+    MethodElement element = propagatedElement;
+    if (element == null) {
+      element = staticElement;
+    }
+    return element;
+  }
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_operand)..add(operator);
+
+  @override
+  Token get endToken => operator;
+
+  /**
+   * Return the expression computing the operand for the operator.
+   */
+  Expression get operand => _operand;
+
+  /**
+   * Set the expression computing the operand for the operator to the given
+   * [expression].
+   */
+  void set operand(Expression expression) {
+    _operand = _becomeParentOf(expression);
+  }
+
+  @override
+  int get precedence => 15;
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on propagated type information, then return the parameter
+   * element representing the parameter to which the value of the operand will
+   * be bound. Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.propagatedParameterElement"
+  ParameterElement get propagatedParameterElementForOperand {
+    return _propagatedParameterElementForOperand;
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on static type information, then return the parameter element
+   * representing the parameter to which the value of the operand will be bound.
+   * Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.propagatedParameterElement"
+  ParameterElement get staticParameterElementForOperand {
+    return _staticParameterElementForOperand;
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on propagated type information, then return the parameter
+   * element representing the parameter to which the value of the operand will
+   * be bound. Otherwise, return `null`.
+   */
+  ParameterElement get _propagatedParameterElementForOperand {
+    if (propagatedElement == null) {
+      return null;
+    }
+    List<ParameterElement> parameters = propagatedElement.parameters;
+    if (parameters.length < 1) {
+      return null;
+    }
+    return parameters[0];
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on static type information, then return the parameter element
+   * representing the parameter to which the value of the operand will be bound.
+   * Otherwise, return `null`.
+   */
+  ParameterElement get _staticParameterElementForOperand {
+    if (staticElement == null) {
+      return null;
+    }
+    List<ParameterElement> parameters = staticElement.parameters;
+    if (parameters.length < 1) {
+      return null;
+    }
+    return parameters[0];
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitPostfixExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_operand, visitor);
+  }
+}
+
+/**
+ * An identifier that is prefixed or an access to an object property where the
+ * target of the property access is a simple identifier.
+ *
+ * > prefixedIdentifier ::=
+ * >     [SimpleIdentifier] '.' [SimpleIdentifier]
+ */
+class PrefixedIdentifier extends Identifier {
+  /**
+   * The prefix associated with the library in which the identifier is defined.
+   */
+  SimpleIdentifier _prefix;
+
+  /**
+   * The period used to separate the prefix from the identifier.
+   */
+  Token period;
+
+  /**
+   * The identifier being prefixed.
+   */
+  SimpleIdentifier _identifier;
+
+  /**
+   * Initialize a newly created prefixed identifier.
+   */
+  PrefixedIdentifier(
+      SimpleIdentifier prefix, this.period, SimpleIdentifier identifier) {
+    _prefix = _becomeParentOf(prefix);
+    _identifier = _becomeParentOf(identifier);
+  }
+
+  @override
+  Token get beginToken => _prefix.beginToken;
+
+  @override
+  Element get bestElement {
+    if (_identifier == null) {
+      return null;
+    }
+    return _identifier.bestElement;
+  }
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_prefix)..add(period)..add(_identifier);
+
+  @override
+  Token get endToken => _identifier.endToken;
+
+  /**
+   * Return the identifier being prefixed.
+   */
+  SimpleIdentifier get identifier => _identifier;
+
+  /**
+   * Set the identifier being prefixed to the given [identifier].
+   */
+  void set identifier(SimpleIdentifier identifier) {
+    _identifier = _becomeParentOf(identifier);
+  }
+
+  /**
+   * Return `true` if this type is a deferred type. If the AST structure has not
+   * been resolved, then return `false`.
+   *
+   * 15.1 Static Types: A type <i>T</i> is deferred iff it is of the form
+   * </i>p.T</i> where <i>p</i> is a deferred prefix.
+   */
+  bool get isDeferred {
+    Element element = _prefix.staticElement;
+    if (element is! PrefixElement) {
+      return false;
+    }
+    PrefixElement prefixElement = element as PrefixElement;
+    List<ImportElement> imports =
+        prefixElement.enclosingElement.getImportsWithPrefix(prefixElement);
+    if (imports.length != 1) {
+      return false;
+    }
+    return imports[0].isDeferred;
+  }
+
+  @override
+  String get name => "${_prefix.name}.${_identifier.name}";
+
+  @override
+  int get precedence => 15;
+
+  /**
+   * Return the prefix associated with the library in which the identifier is
+   * defined.
+   */
+  SimpleIdentifier get prefix => _prefix;
+
+  /**
+   * Set the prefix associated with the library in which the identifier is
+   * defined to the given [identifier].
+   */
+  void set prefix(SimpleIdentifier identifier) {
+    _prefix = _becomeParentOf(identifier);
+  }
+
+  @override
+  Element get propagatedElement {
+    if (_identifier == null) {
+      return null;
+    }
+    return _identifier.propagatedElement;
+  }
+
+  @override
+  Element get staticElement {
+    if (_identifier == null) {
+      return null;
+    }
+    return _identifier.staticElement;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitPrefixedIdentifier(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_prefix, visitor);
+    _safelyVisitChild(_identifier, visitor);
+  }
+}
+
+/**
+ * A prefix unary expression.
+ *
+ * > prefixExpression ::=
+ * >     [Token] [Expression]
+ */
+class PrefixExpression extends Expression {
+  /**
+   * The prefix operator being applied to the operand.
+   */
+  Token operator;
+
+  /**
+   * The expression computing the operand for the operator.
+   */
+  Expression _operand;
+
+  /**
+   * The element associated with the operator based on the static type of the
+   * operand, or `null` if the AST structure has not been resolved, if the
+   * operator is not user definable, or if the operator could not be resolved.
+   */
+  MethodElement staticElement;
+
+  /**
+   * The element associated with the operator based on the propagated type of
+   * the operand, or `null` if the AST structure has not been resolved, if the
+   * operator is not user definable, or if the operator could not be resolved.
+   */
+  MethodElement propagatedElement;
+
+  /**
+   * Initialize a newly created prefix expression.
+   */
+  PrefixExpression(this.operator, Expression operand) {
+    _operand = _becomeParentOf(operand);
+  }
+
+  @override
+  Token get beginToken => operator;
+
+  /**
+   * Return the best element available for this operator. If resolution was able
+   * to find a better element based on type propagation, that element will be
+   * returned. Otherwise, the element found using the result of static analysis
+   * will be returned. If resolution has not been performed, then `null` will be
+   * returned.
+   */
+  MethodElement get bestElement {
+    MethodElement element = propagatedElement;
+    if (element == null) {
+      element = staticElement;
+    }
+    return element;
+  }
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(operator)..add(_operand);
+
+  @override
+  Token get endToken => _operand.endToken;
+
+  /**
+   * Return the expression computing the operand for the operator.
+   */
+  Expression get operand => _operand;
+
+  /**
+   * Set the expression computing the operand for the operator to the given
+   * [expression].
+   */
+  void set operand(Expression expression) {
+    _operand = _becomeParentOf(expression);
+  }
+
+  @override
+  int get precedence => 14;
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on propagated type information, then return the parameter
+   * element representing the parameter to which the value of the operand will
+   * be bound. Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.propagatedParameterElement"
+  ParameterElement get propagatedParameterElementForOperand {
+    return _propagatedParameterElementForOperand;
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on static type information, then return the parameter element
+   * representing the parameter to which the value of the operand will be bound.
+   * Otherwise, return `null`.
+   */
+  @deprecated // Use "expression.propagatedParameterElement"
+  ParameterElement get staticParameterElementForOperand {
+    return _staticParameterElementForOperand;
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on propagated type information, then return the parameter
+   * element representing the parameter to which the value of the operand will
+   * be bound. Otherwise, return `null`.
+   */
+  ParameterElement get _propagatedParameterElementForOperand {
+    if (propagatedElement == null) {
+      return null;
+    }
+    List<ParameterElement> parameters = propagatedElement.parameters;
+    if (parameters.length < 1) {
+      return null;
+    }
+    return parameters[0];
+  }
+
+  /**
+   * If the AST structure has been resolved, and the function being invoked is
+   * known based on static type information, then return the parameter element
+   * representing the parameter to which the value of the operand will be bound.
+   * Otherwise, return `null`.
+   */
+  ParameterElement get _staticParameterElementForOperand {
+    if (staticElement == null) {
+      return null;
+    }
+    List<ParameterElement> parameters = staticElement.parameters;
+    if (parameters.length < 1) {
+      return null;
+    }
+    return parameters[0];
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitPrefixExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_operand, visitor);
+  }
+}
+
+/**
+ * The access of a property of an object.
+ *
+ * Note, however, that accesses to properties of objects can also be represented
+ * as [PrefixedIdentifier] nodes in cases where the target is also a simple
+ * identifier.
+ *
+ * > propertyAccess ::=
+ * >     [Expression] '.' [SimpleIdentifier]
+ */
+class PropertyAccess extends Expression {
+  /**
+   * The expression computing the object defining the property being accessed.
+   */
+  Expression _target;
+
+  /**
+   * The property access operator.
+   */
+  Token operator;
+
+  /**
+   * The name of the property being accessed.
+   */
+  SimpleIdentifier _propertyName;
+
+  /**
+   * Initialize a newly created property access expression.
+   */
+  PropertyAccess(
+      Expression target, this.operator, SimpleIdentifier propertyName) {
+    _target = _becomeParentOf(target);
+    _propertyName = _becomeParentOf(propertyName);
+  }
+
+  @override
+  Token get beginToken {
+    if (_target != null) {
+      return _target.beginToken;
+    }
+    return operator;
+  }
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_target)..add(operator)..add(_propertyName);
+
+  @override
+  Token get endToken => _propertyName.endToken;
+
+  @override
+  bool get isAssignable => true;
+
+  /**
+   * Return `true` if this expression is cascaded. If it is, then the target of
+   * this expression is not stored locally but is stored in the nearest ancestor
+   * that is a [CascadeExpression].
+   */
+  bool get isCascaded =>
+      operator != null && operator.type == TokenType.PERIOD_PERIOD;
+
+  @override
+  int get precedence => 15;
+
+  /**
+   * Return the name of the property being accessed.
+   */
+  SimpleIdentifier get propertyName => _propertyName;
+
+  /**
+   * Set the name of the property being accessed to the given [identifier].
+   */
+  void set propertyName(SimpleIdentifier identifier) {
+    _propertyName = _becomeParentOf(identifier);
+  }
+
+  /**
+   * Return the expression used to compute the receiver of the invocation. If
+   * this invocation is not part of a cascade expression, then this is the same
+   * as [target]. If this invocation is part of a cascade expression, then the
+   * target stored with the cascade expression is returned.
+   */
+  Expression get realTarget {
+    if (isCascaded) {
+      AstNode ancestor = parent;
+      while (ancestor is! CascadeExpression) {
+        if (ancestor == null) {
+          return _target;
+        }
+        ancestor = ancestor.parent;
+      }
+      return (ancestor as CascadeExpression).target;
+    }
+    return _target;
+  }
+
+  /**
+   * Return the expression computing the object defining the property being
+   * accessed, or `null` if this property access is part of a cascade expression.
+   *
+   * Use [realTarget] to get the target independent of whether this is part of a
+   * cascade expression.
+   */
+  Expression get target => _target;
+
+  /**
+   * Set the expression computing the object defining the property being
+   * accessed to the given [expression].
+   */
+  void set target(Expression expression) {
+    _target = _becomeParentOf(expression);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitPropertyAccess(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_target, visitor);
+    _safelyVisitChild(_propertyName, visitor);
+  }
+}
+
+/**
+ * An AST visitor that will recursively visit all of the nodes in an AST
+ * structure. For example, using an instance of this class to visit a [Block]
+ * will also cause all of the statements in the block to be visited.
+ *
+ * Subclasses that override a visit method must either invoke the overridden
+ * visit method or must explicitly ask the visited node to visit its children.
+ * Failure to do so will cause the children of the visited node to not be
+ * visited.
+ */
+class RecursiveAstVisitor<R> implements AstVisitor<R> {
+  @override
+  R visitAdjacentStrings(AdjacentStrings node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitAnnotation(Annotation node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitArgumentList(ArgumentList node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitAsExpression(AsExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitAssertStatement(AssertStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitAssignmentExpression(AssignmentExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitAwaitExpression(AwaitExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitBinaryExpression(BinaryExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitBlock(Block node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitBlockFunctionBody(BlockFunctionBody node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitBooleanLiteral(BooleanLiteral node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitBreakStatement(BreakStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitCascadeExpression(CascadeExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitCatchClause(CatchClause node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitClassDeclaration(ClassDeclaration node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitClassTypeAlias(ClassTypeAlias node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitComment(Comment node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitCommentReference(CommentReference node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitCompilationUnit(CompilationUnit node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitConditionalExpression(ConditionalExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitConstructorDeclaration(ConstructorDeclaration node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitConstructorName(ConstructorName node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitContinueStatement(ContinueStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitDeclaredIdentifier(DeclaredIdentifier node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitDefaultFormalParameter(DefaultFormalParameter node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitDoStatement(DoStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitDoubleLiteral(DoubleLiteral node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitEmptyFunctionBody(EmptyFunctionBody node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitEmptyStatement(EmptyStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitEnumConstantDeclaration(EnumConstantDeclaration node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitEnumDeclaration(EnumDeclaration node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitExportDirective(ExportDirective node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitExpressionFunctionBody(ExpressionFunctionBody node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitExpressionStatement(ExpressionStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitExtendsClause(ExtendsClause node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitFieldDeclaration(FieldDeclaration node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitFieldFormalParameter(FieldFormalParameter node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitForEachStatement(ForEachStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitFormalParameterList(FormalParameterList node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitForStatement(ForStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitFunctionDeclaration(FunctionDeclaration node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitFunctionDeclarationStatement(FunctionDeclarationStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitFunctionExpression(FunctionExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitFunctionExpressionInvocation(FunctionExpressionInvocation node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitFunctionTypeAlias(FunctionTypeAlias node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitHideCombinator(HideCombinator node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitIfStatement(IfStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitImplementsClause(ImplementsClause node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitImportDirective(ImportDirective node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitIndexExpression(IndexExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitInstanceCreationExpression(InstanceCreationExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitIntegerLiteral(IntegerLiteral node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitInterpolationExpression(InterpolationExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitInterpolationString(InterpolationString node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitIsExpression(IsExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitLabel(Label node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitLabeledStatement(LabeledStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitLibraryDirective(LibraryDirective node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitLibraryIdentifier(LibraryIdentifier node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitListLiteral(ListLiteral node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitMapLiteral(MapLiteral node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitMapLiteralEntry(MapLiteralEntry node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitMethodDeclaration(MethodDeclaration node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitMethodInvocation(MethodInvocation node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitNamedExpression(NamedExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitNativeClause(NativeClause node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitNativeFunctionBody(NativeFunctionBody node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitNullLiteral(NullLiteral node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitParenthesizedExpression(ParenthesizedExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitPartDirective(PartDirective node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitPartOfDirective(PartOfDirective node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitPostfixExpression(PostfixExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitPrefixedIdentifier(PrefixedIdentifier node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitPrefixExpression(PrefixExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitPropertyAccess(PropertyAccess node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitRethrowExpression(RethrowExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitReturnStatement(ReturnStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitScriptTag(ScriptTag node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitShowCombinator(ShowCombinator node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitSimpleFormalParameter(SimpleFormalParameter node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitSimpleIdentifier(SimpleIdentifier node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitSimpleStringLiteral(SimpleStringLiteral node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitStringInterpolation(StringInterpolation node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitSuperConstructorInvocation(SuperConstructorInvocation node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitSuperExpression(SuperExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitSwitchCase(SwitchCase node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitSwitchDefault(SwitchDefault node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitSwitchStatement(SwitchStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitSymbolLiteral(SymbolLiteral node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitThisExpression(ThisExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitThrowExpression(ThrowExpression node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitTryStatement(TryStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitTypeArgumentList(TypeArgumentList node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitTypeName(TypeName node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitTypeParameter(TypeParameter node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitTypeParameterList(TypeParameterList node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitVariableDeclaration(VariableDeclaration node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitVariableDeclarationList(VariableDeclarationList node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitVariableDeclarationStatement(VariableDeclarationStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitWhileStatement(WhileStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitWithClause(WithClause node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitYieldStatement(YieldStatement node) {
+    node.visitChildren(this);
+    return null;
+  }
+}
+
+/**
+ * The invocation of a constructor in the same class from within a constructor's
+ * initialization list.
+ *
+ * > redirectingConstructorInvocation ::=
+ * >     'this' ('.' identifier)? arguments
+ */
+class RedirectingConstructorInvocation extends ConstructorInitializer {
+  /**
+   * The token for the 'this' keyword.
+   */
+  Token thisKeyword;
+
+  /**
+   * The token for the period before the name of the constructor that is being
+   * invoked, or `null` if the unnamed constructor is being invoked.
+   */
+  Token period;
+
+  /**
+   * The name of the constructor that is being invoked, or `null` if the unnamed
+   * constructor is being invoked.
+   */
+  SimpleIdentifier _constructorName;
+
+  /**
+   * The list of arguments to the constructor.
+   */
+  ArgumentList _argumentList;
+
+  /**
+   * The element associated with the constructor based on static type
+   * information, or `null` if the AST structure has not been resolved or if the
+   * constructor could not be resolved.
+   */
+  ConstructorElement staticElement;
+
+  /**
+   * Initialize a newly created redirecting invocation to invoke the constructor
+   * with the given name with the given arguments. The [constructorName] can be
+   * `null` if the constructor being invoked is the unnamed constructor.
+   */
+  RedirectingConstructorInvocation(this.thisKeyword, this.period,
+      SimpleIdentifier constructorName, ArgumentList argumentList) {
+    _constructorName = _becomeParentOf(constructorName);
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  /**
+   * Return the list of arguments to the constructor.
+   */
+  ArgumentList get argumentList => _argumentList;
+
+  /**
+   * Set the list of arguments to the constructor to the given [argumentList].
+   */
+  void set argumentList(ArgumentList argumentList) {
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  @override
+  Token get beginToken => thisKeyword;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(thisKeyword)
+    ..add(period)
+    ..add(_constructorName)
+    ..add(_argumentList);
+
+  /**
+   * Return the name of the constructor that is being invoked, or `null` if the
+   * unnamed constructor is being invoked.
+   */
+  SimpleIdentifier get constructorName => _constructorName;
+
+  /**
+   * Set the name of the constructor that is being invoked to the given
+   * [identifier].
+   */
+  void set constructorName(SimpleIdentifier identifier) {
+    _constructorName = _becomeParentOf(identifier);
+  }
+
+  @override
+  Token get endToken => _argumentList.endToken;
+
+  /**
+   * Return the token for the 'this' keyword.
+   */
+  @deprecated // Use "this.thisKeyword"
+  Token get keyword => thisKeyword;
+
+  /**
+   * Set the token for the 'this' keyword to the given [token].
+   */
+  @deprecated // Use "this.thisKeyword"
+  set keyword(Token token) {
+    thisKeyword = token;
+  }
+
+  @override
+  accept(AstVisitor visitor) =>
+      visitor.visitRedirectingConstructorInvocation(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_constructorName, visitor);
+    _safelyVisitChild(_argumentList, visitor);
+  }
+}
+
+/**
+ * A rethrow expression.
+ *
+ * > rethrowExpression ::=
+ * >     'rethrow'
+ */
+class RethrowExpression extends Expression {
+  /**
+   * The token representing the 'rethrow' keyword.
+   */
+  Token rethrowKeyword;
+
+  /**
+   * Initialize a newly created rethrow expression.
+   */
+  RethrowExpression(this.rethrowKeyword);
+
+  @override
+  Token get beginToken => rethrowKeyword;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(rethrowKeyword);
+
+  @override
+  Token get endToken => rethrowKeyword;
+
+  /**
+   * Return the token representing the 'rethrow' keyword.
+   */
+  @deprecated // Use "this.rethrowKeyword"
+  Token get keyword => rethrowKeyword;
+
+  /**
+   * Set the token representing the 'rethrow' keyword to the given [token].
+   */
+  @deprecated // Use "this.rethrowKeyword"
+  set keyword(Token token) {
+    rethrowKeyword = token;
+  }
+
+  @override
+  int get precedence => 0;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitRethrowExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+}
+
+/**
+ * A return statement.
+ *
+ * > returnStatement ::=
+ * >     'return' [Expression]? ';'
+ */
+class ReturnStatement extends Statement {
+  /**
+   * The token representing the 'return' keyword.
+   */
+  Token returnKeyword;
+
+  /**
+   * The expression computing the value to be returned, or `null` if no explicit
+   * value was provided.
+   */
+  Expression _expression;
+
+  /**
+   * The semicolon terminating the statement.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created return statement. The [expression] can be `null`
+   * if no explicit value was provided.
+   */
+  ReturnStatement(this.returnKeyword, Expression expression, this.semicolon) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get beginToken => returnKeyword;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(returnKeyword)..add(_expression)..add(semicolon);
+
+  @override
+  Token get endToken => semicolon;
+
+  /**
+   * Return the expression computing the value to be returned, or `null` if no
+   * explicit value was provided.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression computing the value to be returned to the given
+   * [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  /**
+   * Return the token representing the 'return' keyword.
+   */
+  @deprecated // Use "this.returnKeyword"
+  Token get keyword => returnKeyword;
+
+  /**
+   * Set the token representing the 'return' keyword to the given [token].
+   */
+  @deprecated // Use "this.returnKeyword"
+  set keyword(Token token) {
+    returnKeyword = token;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitReturnStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+  }
+}
+
+/**
+ * Traverse the AST from initial child node to successive parents, building a
+ * collection of local variable and parameter names visible to the initial child
+ * node. In case of name shadowing, the first name seen is the most specific one
+ * so names are not redefined.
+ *
+ * Completion test code coverage is 95%. The two basic blocks that are not
+ * executed cannot be executed. They are included for future reference.
+ */
+class ScopedNameFinder extends GeneralizingAstVisitor<Object> {
+  Declaration _declarationNode;
+
+  AstNode _immediateChild;
+
+  Map<String, SimpleIdentifier> _locals =
+      new HashMap<String, SimpleIdentifier>();
+
+  final int _position;
+
+  bool _referenceIsWithinLocalFunction = false;
+
+  ScopedNameFinder(this._position);
+
+  Declaration get declaration => _declarationNode;
+
+  Map<String, SimpleIdentifier> get locals => _locals;
+
+  @override
+  Object visitBlock(Block node) {
+    _checkStatements(node.statements);
+    return super.visitBlock(node);
+  }
+
+  @override
+  Object visitCatchClause(CatchClause node) {
+    _addToScope(node.exceptionParameter);
+    _addToScope(node.stackTraceParameter);
+    return super.visitCatchClause(node);
+  }
+
+  @override
+  Object visitConstructorDeclaration(ConstructorDeclaration node) {
+    if (!identical(_immediateChild, node.parameters)) {
+      _addParameters(node.parameters.parameters);
+    }
+    _declarationNode = node;
+    return null;
+  }
+
+  @override
+  Object visitFieldDeclaration(FieldDeclaration node) {
+    _declarationNode = node;
+    return null;
+  }
+
+  @override
+  Object visitForEachStatement(ForEachStatement node) {
+    DeclaredIdentifier loopVariable = node.loopVariable;
+    if (loopVariable != null) {
+      _addToScope(loopVariable.identifier);
+    }
+    return super.visitForEachStatement(node);
+  }
+
+  @override
+  Object visitForStatement(ForStatement node) {
+    if (!identical(_immediateChild, node.variables) && node.variables != null) {
+      _addVariables(node.variables.variables);
+    }
+    return super.visitForStatement(node);
+  }
+
+  @override
+  Object visitFunctionDeclaration(FunctionDeclaration node) {
+    if (node.parent is! FunctionDeclarationStatement) {
+      _declarationNode = node;
+      return null;
+    }
+    return super.visitFunctionDeclaration(node);
+  }
+
+  @override
+  Object visitFunctionDeclarationStatement(FunctionDeclarationStatement node) {
+    _referenceIsWithinLocalFunction = true;
+    return super.visitFunctionDeclarationStatement(node);
+  }
+
+  @override
+  Object visitFunctionExpression(FunctionExpression node) {
+    if (node.parameters != null &&
+        !identical(_immediateChild, node.parameters)) {
+      _addParameters(node.parameters.parameters);
+    }
+    return super.visitFunctionExpression(node);
+  }
+
+  @override
+  Object visitMethodDeclaration(MethodDeclaration node) {
+    _declarationNode = node;
+    if (node.parameters == null) {
+      return null;
+    }
+    if (!identical(_immediateChild, node.parameters)) {
+      _addParameters(node.parameters.parameters);
+    }
+    return null;
+  }
+
+  @override
+  Object visitNode(AstNode node) {
+    _immediateChild = node;
+    AstNode parent = node.parent;
+    if (parent != null) {
+      parent.accept(this);
+    }
+    return null;
+  }
+
+  @override
+  Object visitSwitchMember(SwitchMember node) {
+    _checkStatements(node.statements);
+    return super.visitSwitchMember(node);
+  }
+
+  @override
+  Object visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
+    _declarationNode = node;
+    return null;
+  }
+
+  @override
+  Object visitTypeAlias(TypeAlias node) {
+    _declarationNode = node;
+    return null;
+  }
+
+  void _addParameters(NodeList<FormalParameter> vars) {
+    for (FormalParameter var2 in vars) {
+      _addToScope(var2.identifier);
+    }
+  }
+
+  void _addToScope(SimpleIdentifier identifier) {
+    if (identifier != null && _isInRange(identifier)) {
+      String name = identifier.name;
+      if (!_locals.containsKey(name)) {
+        _locals[name] = identifier;
+      }
+    }
+  }
+
+  void _addVariables(NodeList<VariableDeclaration> variables) {
+    for (VariableDeclaration variable in variables) {
+      _addToScope(variable.name);
+    }
+  }
+
+  /**
+   * Check the given list of [statements] for any that come before the immediate
+   * child and that define a name that would be visible to the immediate child.
+   */
+  void _checkStatements(List<Statement> statements) {
+    for (Statement statement in statements) {
+      if (identical(statement, _immediateChild)) {
+        return;
+      }
+      if (statement is VariableDeclarationStatement) {
+        _addVariables(statement.variables.variables);
+      } else if (statement is FunctionDeclarationStatement &&
+          !_referenceIsWithinLocalFunction) {
+        _addToScope(statement.functionDeclaration.name);
+      }
+    }
+  }
+
+  bool _isInRange(AstNode node) {
+    if (_position < 0) {
+      // if source position is not set then all nodes are in range
+      return true;
+      // not reached
+    }
+    return node.end < _position;
+  }
+}
+
+/**
+ * A script tag that can optionally occur at the beginning of a compilation unit.
+ *
+ * > scriptTag ::=
+ * >     '#!' (~NEWLINE)* NEWLINE
+ */
+class ScriptTag extends AstNode {
+  /**
+   * The token representing this script tag.
+   */
+  Token scriptTag;
+
+  /**
+   * Initialize a newly created script tag.
+   */
+  ScriptTag(this.scriptTag);
+
+  @override
+  Token get beginToken => scriptTag;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(scriptTag);
+
+  @override
+  Token get endToken => scriptTag;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitScriptTag(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+}
+
+/**
+ * A combinator that restricts the names being imported to those in a given list.
+ *
+ * > showCombinator ::=
+ * >     'show' [SimpleIdentifier] (',' [SimpleIdentifier])*
+ */
+class ShowCombinator extends Combinator {
+  /**
+   * The list of names from the library that are made visible by this combinator.
+   */
+  NodeList<SimpleIdentifier> _shownNames;
+
+  /**
+   * Initialize a newly created import show combinator.
+   */
+  ShowCombinator(Token keyword, List<SimpleIdentifier> shownNames)
+      : super(keyword) {
+    _shownNames = new NodeList<SimpleIdentifier>(this, shownNames);
+  }
+
+  /**
+   * TODO(paulberry): add commas.
+   */
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(keyword)
+    ..addAll(_shownNames);
+
+  @override
+  Token get endToken => _shownNames.endToken;
+
+  /**
+   * Return the list of names from the library that are made visible by this
+   * combinator.
+   */
+  NodeList<SimpleIdentifier> get shownNames => _shownNames;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitShowCombinator(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _shownNames.accept(visitor);
+  }
+}
+
+/**
+ * An AST visitor that will do nothing when visiting an AST node. It is intended
+ * to be a superclass for classes that use the visitor pattern primarily as a
+ * dispatch mechanism (and hence don't need to recursively visit a whole
+ * structure) and that only need to visit a small number of node types.
+ */
+class SimpleAstVisitor<R> implements AstVisitor<R> {
+  @override
+  R visitAdjacentStrings(AdjacentStrings node) => null;
+
+  @override
+  R visitAnnotation(Annotation node) => null;
+
+  @override
+  R visitArgumentList(ArgumentList node) => null;
+
+  @override
+  R visitAsExpression(AsExpression node) => null;
+
+  @override
+  R visitAssertStatement(AssertStatement node) => null;
+
+  @override
+  R visitAssignmentExpression(AssignmentExpression node) => null;
+
+  @override
+  R visitAwaitExpression(AwaitExpression node) => null;
+
+  @override
+  R visitBinaryExpression(BinaryExpression node) => null;
+
+  @override
+  R visitBlock(Block node) => null;
+
+  @override
+  R visitBlockFunctionBody(BlockFunctionBody node) => null;
+
+  @override
+  R visitBooleanLiteral(BooleanLiteral node) => null;
+
+  @override
+  R visitBreakStatement(BreakStatement node) => null;
+
+  @override
+  R visitCascadeExpression(CascadeExpression node) => null;
+
+  @override
+  R visitCatchClause(CatchClause node) => null;
+
+  @override
+  R visitClassDeclaration(ClassDeclaration node) => null;
+
+  @override
+  R visitClassTypeAlias(ClassTypeAlias node) => null;
+
+  @override
+  R visitComment(Comment node) => null;
+
+  @override
+  R visitCommentReference(CommentReference node) => null;
+
+  @override
+  R visitCompilationUnit(CompilationUnit node) => null;
+
+  @override
+  R visitConditionalExpression(ConditionalExpression node) => null;
+
+  @override
+  R visitConstructorDeclaration(ConstructorDeclaration node) => null;
+
+  @override
+  R visitConstructorFieldInitializer(ConstructorFieldInitializer node) => null;
+
+  @override
+  R visitConstructorName(ConstructorName node) => null;
+
+  @override
+  R visitContinueStatement(ContinueStatement node) => null;
+
+  @override
+  R visitDeclaredIdentifier(DeclaredIdentifier node) => null;
+
+  @override
+  R visitDefaultFormalParameter(DefaultFormalParameter node) => null;
+
+  @override
+  R visitDoStatement(DoStatement node) => null;
+
+  @override
+  R visitDoubleLiteral(DoubleLiteral node) => null;
+
+  @override
+  R visitEmptyFunctionBody(EmptyFunctionBody node) => null;
+
+  @override
+  R visitEmptyStatement(EmptyStatement node) => null;
+
+  @override
+  R visitEnumConstantDeclaration(EnumConstantDeclaration node) => null;
+
+  @override
+  R visitEnumDeclaration(EnumDeclaration node) => null;
+
+  @override
+  R visitExportDirective(ExportDirective node) => null;
+
+  @override
+  R visitExpressionFunctionBody(ExpressionFunctionBody node) => null;
+
+  @override
+  R visitExpressionStatement(ExpressionStatement node) => null;
+
+  @override
+  R visitExtendsClause(ExtendsClause node) => null;
+
+  @override
+  R visitFieldDeclaration(FieldDeclaration node) => null;
+
+  @override
+  R visitFieldFormalParameter(FieldFormalParameter node) => null;
+
+  @override
+  R visitForEachStatement(ForEachStatement node) => null;
+
+  @override
+  R visitFormalParameterList(FormalParameterList node) => null;
+
+  @override
+  R visitForStatement(ForStatement node) => null;
+
+  @override
+  R visitFunctionDeclaration(FunctionDeclaration node) => null;
+
+  @override
+  R visitFunctionDeclarationStatement(FunctionDeclarationStatement node) =>
+      null;
+
+  @override
+  R visitFunctionExpression(FunctionExpression node) => null;
+
+  @override
+  R visitFunctionExpressionInvocation(FunctionExpressionInvocation node) =>
+      null;
+
+  @override
+  R visitFunctionTypeAlias(FunctionTypeAlias node) => null;
+
+  @override
+  R visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) =>
+      null;
+
+  @override
+  R visitHideCombinator(HideCombinator node) => null;
+
+  @override
+  R visitIfStatement(IfStatement node) => null;
+
+  @override
+  R visitImplementsClause(ImplementsClause node) => null;
+
+  @override
+  R visitImportDirective(ImportDirective node) => null;
+
+  @override
+  R visitIndexExpression(IndexExpression node) => null;
+
+  @override
+  R visitInstanceCreationExpression(InstanceCreationExpression node) => null;
+
+  @override
+  R visitIntegerLiteral(IntegerLiteral node) => null;
+
+  @override
+  R visitInterpolationExpression(InterpolationExpression node) => null;
+
+  @override
+  R visitInterpolationString(InterpolationString node) => null;
+
+  @override
+  R visitIsExpression(IsExpression node) => null;
+
+  @override
+  R visitLabel(Label node) => null;
+
+  @override
+  R visitLabeledStatement(LabeledStatement node) => null;
+
+  @override
+  R visitLibraryDirective(LibraryDirective node) => null;
+
+  @override
+  R visitLibraryIdentifier(LibraryIdentifier node) => null;
+
+  @override
+  R visitListLiteral(ListLiteral node) => null;
+
+  @override
+  R visitMapLiteral(MapLiteral node) => null;
+
+  @override
+  R visitMapLiteralEntry(MapLiteralEntry node) => null;
+
+  @override
+  R visitMethodDeclaration(MethodDeclaration node) => null;
+
+  @override
+  R visitMethodInvocation(MethodInvocation node) => null;
+
+  @override
+  R visitNamedExpression(NamedExpression node) => null;
+
+  @override
+  R visitNativeClause(NativeClause node) => null;
+
+  @override
+  R visitNativeFunctionBody(NativeFunctionBody node) => null;
+
+  @override
+  R visitNullLiteral(NullLiteral node) => null;
+
+  @override
+  R visitParenthesizedExpression(ParenthesizedExpression node) => null;
+
+  @override
+  R visitPartDirective(PartDirective node) => null;
+
+  @override
+  R visitPartOfDirective(PartOfDirective node) => null;
+
+  @override
+  R visitPostfixExpression(PostfixExpression node) => null;
+
+  @override
+  R visitPrefixedIdentifier(PrefixedIdentifier node) => null;
+
+  @override
+  R visitPrefixExpression(PrefixExpression node) => null;
+
+  @override
+  R visitPropertyAccess(PropertyAccess node) => null;
+
+  @override
+  R visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) => null;
+
+  @override
+  R visitRethrowExpression(RethrowExpression node) => null;
+
+  @override
+  R visitReturnStatement(ReturnStatement node) => null;
+
+  @override
+  R visitScriptTag(ScriptTag node) => null;
+
+  @override
+  R visitShowCombinator(ShowCombinator node) => null;
+
+  @override
+  R visitSimpleFormalParameter(SimpleFormalParameter node) => null;
+
+  @override
+  R visitSimpleIdentifier(SimpleIdentifier node) => null;
+
+  @override
+  R visitSimpleStringLiteral(SimpleStringLiteral node) => null;
+
+  @override
+  R visitStringInterpolation(StringInterpolation node) => null;
+
+  @override
+  R visitSuperConstructorInvocation(SuperConstructorInvocation node) => null;
+
+  @override
+  R visitSuperExpression(SuperExpression node) => null;
+
+  @override
+  R visitSwitchCase(SwitchCase node) => null;
+
+  @override
+  R visitSwitchDefault(SwitchDefault node) => null;
+
+  @override
+  R visitSwitchStatement(SwitchStatement node) => null;
+
+  @override
+  R visitSymbolLiteral(SymbolLiteral node) => null;
+
+  @override
+  R visitThisExpression(ThisExpression node) => null;
+
+  @override
+  R visitThrowExpression(ThrowExpression node) => null;
+
+  @override
+  R visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) => null;
+
+  @override
+  R visitTryStatement(TryStatement node) => null;
+
+  @override
+  R visitTypeArgumentList(TypeArgumentList node) => null;
+
+  @override
+  R visitTypeName(TypeName node) => null;
+
+  @override
+  R visitTypeParameter(TypeParameter node) => null;
+
+  @override
+  R visitTypeParameterList(TypeParameterList node) => null;
+
+  @override
+  R visitVariableDeclaration(VariableDeclaration node) => null;
+
+  @override
+  R visitVariableDeclarationList(VariableDeclarationList node) => null;
+
+  @override
+  R visitVariableDeclarationStatement(VariableDeclarationStatement node) =>
+      null;
+
+  @override
+  R visitWhileStatement(WhileStatement node) => null;
+
+  @override
+  R visitWithClause(WithClause node) => null;
+
+  @override
+  R visitYieldStatement(YieldStatement node) => null;
+}
+
+/**
+ * A simple formal parameter.
+ *
+ * > simpleFormalParameter ::=
+ * >     ('final' [TypeName] | 'var' | [TypeName])? [SimpleIdentifier]
+ */
+class SimpleFormalParameter extends NormalFormalParameter {
+  /**
+   * The token representing either the 'final', 'const' or 'var' keyword, or
+   * `null` if no keyword was used.
+   */
+  Token keyword;
+
+  /**
+   * The name of the declared type of the parameter, or `null` if the parameter
+   * does not have a declared type.
+   */
+  TypeName _type;
+
+  /**
+   * Initialize a newly created formal parameter. Either or both of the
+   * [comment] and [metadata] can be `null` if the parameter does not have the
+   * corresponding attribute. The [keyword] can be `null` if a type was
+   * specified. The [type] must be `null` if the keyword is 'var'.
+   */
+  SimpleFormalParameter(Comment comment, List<Annotation> metadata,
+      this.keyword, TypeName type, SimpleIdentifier identifier)
+      : super(comment, metadata, identifier) {
+    _type = _becomeParentOf(type);
+  }
+
+  @override
+  Token get beginToken {
+    NodeList<Annotation> metadata = this.metadata;
+    if (!metadata.isEmpty) {
+      return metadata.beginToken;
+    } else if (keyword != null) {
+      return keyword;
+    } else if (_type != null) {
+      return _type.beginToken;
+    }
+    return identifier.beginToken;
+  }
+
+  @override
+  Iterable get childEntities =>
+      super._childEntities..add(keyword)..add(_type)..add(identifier);
+
+  @override
+  Token get endToken => identifier.endToken;
+
+  @override
+  bool get isConst => (keyword is KeywordToken) &&
+      (keyword as KeywordToken).keyword == Keyword.CONST;
+
+  @override
+  bool get isFinal => (keyword is KeywordToken) &&
+      (keyword as KeywordToken).keyword == Keyword.FINAL;
+
+  /**
+   * Return the name of the declared type of the parameter, or `null` if the
+   * parameter does not have a declared type.
+   */
+  TypeName get type => _type;
+
+  /**
+   * Set the name of the declared type of the parameter to the given [typeName].
+   */
+  void set type(TypeName typeName) {
+    _type = _becomeParentOf(typeName);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitSimpleFormalParameter(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_type, visitor);
+    _safelyVisitChild(identifier, visitor);
+  }
+}
+
+/**
+ * A simple identifier.
+ *
+ * > simpleIdentifier ::=
+ * >     initialCharacter internalCharacter*
+ * >
+ * > initialCharacter ::= '_' | '$' | letter
+ * >
+ * > internalCharacter ::= '_' | '$' | letter | digit
+ */
+class SimpleIdentifier extends Identifier {
+  /**
+   * The token representing the identifier.
+   */
+  Token token;
+
+  /**
+   * The element associated with this identifier based on static type
+   * information, or `null` if the AST structure has not been resolved or if
+   * this identifier could not be resolved.
+   */
+  Element _staticElement;
+
+  /**
+   * The element associated with this identifier based on propagated type
+   * information, or `null` if the AST structure has not been resolved or if
+   * this identifier could not be resolved.
+   */
+  Element _propagatedElement;
+
+  /**
+   * If this expression is both in a getter and setter context, the
+   * [AuxiliaryElements] will be set to hold onto the static and propagated
+   * information. The auxiliary element will hold onto the elements from the
+   * getter context.
+   */
+  AuxiliaryElements auxiliaryElements = null;
+
+  /**
+   * Initialize a newly created identifier.
+   */
+  SimpleIdentifier(this.token);
+
+  @override
+  Token get beginToken => token;
+
+  @override
+  Element get bestElement {
+    if (_propagatedElement == null) {
+      return _staticElement;
+    }
+    return _propagatedElement;
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(token);
+
+  @override
+  Token get endToken => token;
+
+  /**
+   * Returns `true` if this identifier is the "name" part of a prefixed
+   * identifier or a method invocation.
+   */
+  bool get isQualified {
+    AstNode parent = this.parent;
+    if (parent is PrefixedIdentifier) {
+      return identical(parent.identifier, this);
+    }
+    if (parent is PropertyAccess) {
+      return identical(parent.propertyName, this);
+    }
+    if (parent is MethodInvocation) {
+      MethodInvocation invocation = parent;
+      return identical(invocation.methodName, this) &&
+          invocation.realTarget != null;
+    }
+    return false;
+  }
+
+  @override
+  bool get isSynthetic => token.isSynthetic;
+
+  @override
+  String get name => token.lexeme;
+
+  @override
+  int get precedence => 16;
+
+  @override
+  Element get propagatedElement => _propagatedElement;
+
+  /**
+   * Set the element associated with this identifier based on propagated type
+   * information to the given [element].
+   */
+  void set propagatedElement(Element element) {
+    _propagatedElement = _validateElement(element);
+  }
+
+  @override
+  Element get staticElement => _staticElement;
+
+  /**
+   * Set the element associated with this identifier based on static type
+   * information to the given [element].
+   */
+  void set staticElement(Element element) {
+    _staticElement = _validateElement(element);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitSimpleIdentifier(this);
+
+  /**
+   * Return `true` if this identifier is the name being declared in a
+   * declaration.
+   */
+  bool inDeclarationContext() {
+    // TODO(brianwilkerson) Convert this to a getter.
+    AstNode parent = this.parent;
+    if (parent is CatchClause) {
+      CatchClause clause = parent;
+      return identical(this, clause.exceptionParameter) ||
+          identical(this, clause.stackTraceParameter);
+    } else if (parent is ClassDeclaration) {
+      return identical(this, parent.name);
+    } else if (parent is ClassTypeAlias) {
+      return identical(this, parent.name);
+    } else if (parent is ConstructorDeclaration) {
+      return identical(this, parent.name);
+    } else if (parent is DeclaredIdentifier) {
+      return identical(this, parent.identifier);
+    } else if (parent is EnumDeclaration) {
+      return identical(this, parent.name);
+    } else if (parent is EnumConstantDeclaration) {
+      return identical(this, parent.name);
+    } else if (parent is FunctionDeclaration) {
+      return identical(this, parent.name);
+    } else if (parent is FunctionTypeAlias) {
+      return identical(this, parent.name);
+    } else if (parent is ImportDirective) {
+      return identical(this, parent.prefix);
+    } else if (parent is Label) {
+      return identical(this, parent.label) &&
+          (parent.parent is LabeledStatement);
+    } else if (parent is MethodDeclaration) {
+      return identical(this, parent.name);
+    } else if (parent is FunctionTypedFormalParameter ||
+        parent is SimpleFormalParameter) {
+      return identical(this, (parent as NormalFormalParameter).identifier);
+    } else if (parent is TypeParameter) {
+      return identical(this, parent.name);
+    } else if (parent is VariableDeclaration) {
+      return identical(this, parent.name);
+    }
+    return false;
+  }
+
+  /**
+   * Return `true` if this expression is computing a right-hand value.
+   *
+   * Note that [inGetterContext] and [inSetterContext] are not opposites, nor
+   * are they mutually exclusive. In other words, it is possible for both
+   * methods to return `true` when invoked on the same node.
+   */
+  bool inGetterContext() {
+    // TODO(brianwilkerson) Convert this to a getter.
+    AstNode parent = this.parent;
+    AstNode target = this;
+    // skip prefix
+    if (parent is PrefixedIdentifier) {
+      PrefixedIdentifier prefixed = parent as PrefixedIdentifier;
+      if (identical(prefixed.prefix, this)) {
+        return true;
+      }
+      parent = prefixed.parent;
+      target = prefixed;
+    } else if (parent is PropertyAccess) {
+      PropertyAccess access = parent as PropertyAccess;
+      if (identical(access.target, this)) {
+        return true;
+      }
+      parent = access.parent;
+      target = access;
+    }
+    // skip label
+    if (parent is Label) {
+      return false;
+    }
+    // analyze usage
+    if (parent is AssignmentExpression) {
+      if (identical(parent.leftHandSide, target) &&
+          parent.operator.type == TokenType.EQ) {
+        return false;
+      }
+    }
+    if (parent is ForEachStatement) {
+      if (identical(parent.identifier, target)) {
+        return false;
+      }
+    }
+    return true;
+  }
+
+  /**
+   * Return `true` if this expression is computing a left-hand value.
+   *
+   * Note that [inGetterContext] and [inSetterContext] are not opposites, nor
+   * are they mutually exclusive. In other words, it is possible for both
+   * methods to return `true` when invoked on the same node.
+   */
+  bool inSetterContext() {
+    // TODO(brianwilkerson) Convert this to a getter.
+    AstNode parent = this.parent;
+    AstNode target = this;
+    // skip prefix
+    if (parent is PrefixedIdentifier) {
+      PrefixedIdentifier prefixed = parent as PrefixedIdentifier;
+      // if this is the prefix, then return false
+      if (identical(prefixed.prefix, this)) {
+        return false;
+      }
+      parent = prefixed.parent;
+      target = prefixed;
+    } else if (parent is PropertyAccess) {
+      PropertyAccess access = parent as PropertyAccess;
+      if (identical(access.target, this)) {
+        return false;
+      }
+      parent = access.parent;
+      target = access;
+    }
+    // analyze usage
+    if (parent is PrefixExpression) {
+      return parent.operator.type.isIncrementOperator;
+    } else if (parent is PostfixExpression) {
+      return true;
+    } else if (parent is AssignmentExpression) {
+      return identical(parent.leftHandSide, target);
+    } else if (parent is ForEachStatement) {
+      return identical(parent.identifier, target);
+    }
+    return false;
+  }
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+
+  /**
+   * Return the given element if it is valid, or report the problem and return
+   * `null` if it is not appropriate.
+   *
+   * The [parent] is the parent of the element, used for reporting when there is
+   * a problem.
+   * The [isValid] is `true` if the element is appropriate.
+   * The [element] is the element to be associated with this identifier.
+   */
+  Element _returnOrReportElement(
+      AstNode parent, bool isValid, Element element) {
+    if (!isValid) {
+      AnalysisEngine.instance.logger.logInformation(
+          "Internal error: attempting to set the name of a ${parent.runtimeType} to a ${element.runtimeType}",
+          new CaughtException(new AnalysisException(), null));
+      return null;
+    }
+    return element;
+  }
+
+  /**
+   * Return the given [element] if it is an appropriate element based on the
+   * parent of this identifier, or `null` if it is not appropriate.
+   */
+  Element _validateElement(Element element) {
+    if (element == null) {
+      return null;
+    }
+    AstNode parent = this.parent;
+    if (parent is ClassDeclaration && identical(parent.name, this)) {
+      return _returnOrReportElement(parent, element is ClassElement, element);
+    } else if (parent is ClassTypeAlias && identical(parent.name, this)) {
+      return _returnOrReportElement(parent, element is ClassElement, element);
+    } else if (parent is DeclaredIdentifier &&
+        identical(parent.identifier, this)) {
+      return _returnOrReportElement(
+          parent, element is LocalVariableElement, element);
+    } else if (parent is FormalParameter &&
+        identical(parent.identifier, this)) {
+      return _returnOrReportElement(
+          parent, element is ParameterElement, element);
+    } else if (parent is FunctionDeclaration && identical(parent.name, this)) {
+      return _returnOrReportElement(
+          parent, element is ExecutableElement, element);
+    } else if (parent is FunctionTypeAlias && identical(parent.name, this)) {
+      return _returnOrReportElement(
+          parent, element is FunctionTypeAliasElement, element);
+    } else if (parent is MethodDeclaration && identical(parent.name, this)) {
+      return _returnOrReportElement(
+          parent, element is ExecutableElement, element);
+    } else if (parent is TypeParameter && identical(parent.name, this)) {
+      return _returnOrReportElement(
+          parent, element is TypeParameterElement, element);
+    } else if (parent is VariableDeclaration && identical(parent.name, this)) {
+      return _returnOrReportElement(
+          parent, element is VariableElement, element);
+    }
+    return element;
+  }
+}
+
+/**
+ * A string literal expression that does not contain any interpolations.
+ *
+ * > simpleStringLiteral ::=
+ * >     rawStringLiteral
+ * >   | basicStringLiteral
+ * >
+ * > rawStringLiteral ::=
+ * >     'r' basicStringLiteral
+ * >
+ * > simpleStringLiteral ::=
+ * >     multiLineStringLiteral
+ * >   | singleLineStringLiteral
+ * >
+ * > multiLineStringLiteral ::=
+ * >     "'''" characters "'''"
+ * >   | '"""' characters '"""'
+ * >
+ * > singleLineStringLiteral ::=
+ * >     "'" characters "'"
+ * >   | '"' characters '"'
+ */
+class SimpleStringLiteral extends SingleStringLiteral {
+  /**
+   * The token representing the literal.
+   */
+  Token literal;
+
+  /**
+   * The value of the literal.
+   */
+  String _value;
+
+  /**
+   * The toolkit specific element associated with this literal, or `null`.
+   */
+  @deprecated // No replacement
+  Element toolkitElement;
+
+  /**
+   * Initialize a newly created simple string literal.
+   */
+  SimpleStringLiteral(this.literal, String value) {
+    _value = StringUtilities.intern(value);
+  }
+
+  @override
+  Token get beginToken => literal;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(literal);
+
+  @override
+  int get contentsEnd => offset + _helper.end;
+
+  @override
+  int get contentsOffset => offset + _helper.start;
+
+  @override
+  Token get endToken => literal;
+
+  @override
+  bool get isMultiline => _helper.isMultiline;
+
+  @override
+  bool get isRaw => _helper.isRaw;
+
+  @override
+  bool get isSingleQuoted => _helper.isSingleQuoted;
+
+  @override
+  bool get isSynthetic => literal.isSynthetic;
+
+  /**
+   * Return the value of the literal.
+   */
+  String get value => _value;
+
+  /**
+   * Set the value of the literal to the given [string].
+   */
+  void set value(String string) {
+    _value = StringUtilities.intern(_value);
+  }
+
+  StringLexemeHelper get _helper {
+    return new StringLexemeHelper(literal.lexeme, true, true);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitSimpleStringLiteral(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+
+  @override
+  void _appendStringValue(StringBuffer buffer) {
+    buffer.write(value);
+  }
+}
+
+/**
+ * A single string literal expression.
+ *
+ * > singleStringLiteral ::=
+ * >     [SimpleStringLiteral]
+ * >   | [StringInterpolation]
+ */
+abstract class SingleStringLiteral extends StringLiteral {
+  /**
+   * Return the offset of the after-last contents character.
+   */
+  int get contentsEnd;
+
+  /**
+   * Return the offset of the first contents character.
+   * If the string is multiline, then leading whitespaces are skipped.
+   */
+  int get contentsOffset;
+
+  /**
+   * Return `true` if this string literal is a multi-line string.
+   */
+  bool get isMultiline;
+
+  /**
+   * Return `true` if this string literal is a raw string.
+   */
+  bool get isRaw;
+
+  /**
+   * Return `true` if this string literal uses single qoutes (' or ''').
+   * Return `false` if this string literal uses double qoutes (" or """).
+   */
+  bool get isSingleQuoted;
+}
+
+/**
+ * A node that represents a statement.
+ *
+ * > statement ::=
+ * >     [Block]
+ * >   | [VariableDeclarationStatement]
+ * >   | [ForStatement]
+ * >   | [ForEachStatement]
+ * >   | [WhileStatement]
+ * >   | [DoStatement]
+ * >   | [SwitchStatement]
+ * >   | [IfStatement]
+ * >   | [TryStatement]
+ * >   | [BreakStatement]
+ * >   | [ContinueStatement]
+ * >   | [ReturnStatement]
+ * >   | [ExpressionStatement]
+ * >   | [FunctionDeclarationStatement]
+ */
+abstract class Statement extends AstNode {
+  /**
+   * If this is a labeled statement, return the unlabeled portion of the
+   * statement.  Otherwise return the statement itself.
+   */
+  Statement get unlabeled => this;
+}
+
+/**
+ * A string interpolation literal.
+ *
+ * > stringInterpolation ::=
+ * >     ''' [InterpolationElement]* '''
+ * >   | '"' [InterpolationElement]* '"'
+ */
+class StringInterpolation extends SingleStringLiteral {
+  /**
+   * The elements that will be composed to produce the resulting string.
+   */
+  NodeList<InterpolationElement> _elements;
+
+  /**
+   * Initialize a newly created string interpolation expression.
+   */
+  StringInterpolation(List<InterpolationElement> elements) {
+    _elements = new NodeList<InterpolationElement>(this, elements);
+  }
+
+  @override
+  Token get beginToken => _elements.beginToken;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..addAll(_elements);
+
+  @override
+  int get contentsEnd {
+    InterpolationString element = _elements.last;
+    return element.contentsEnd;
+  }
+
+  @override
+  int get contentsOffset {
+    InterpolationString element = _elements.first;
+    return element.contentsOffset;
+  }
+
+  /**
+   * Return the elements that will be composed to produce the resulting string.
+   */
+  NodeList<InterpolationElement> get elements => _elements;
+
+  @override
+  Token get endToken => _elements.endToken;
+
+  @override
+  bool get isMultiline => _firstHelper.isMultiline;
+
+  @override
+  bool get isRaw => false;
+
+  @override
+  bool get isSingleQuoted => _firstHelper.isSingleQuoted;
+
+  StringLexemeHelper get _firstHelper {
+    InterpolationString lastString = _elements.first;
+    String lexeme = lastString.contents.lexeme;
+    return new StringLexemeHelper(lexeme, true, false);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitStringInterpolation(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _elements.accept(visitor);
+  }
+
+  @override
+  void _appendStringValue(StringBuffer buffer) {
+    throw new IllegalArgumentException();
+  }
+}
+
+/**
+ * A helper for analyzing string lexemes.
+ */
+class StringLexemeHelper {
+  final String lexeme;
+  final bool isFirst;
+  final bool isLast;
+
+  bool isRaw = false;
+  bool isSingleQuoted = false;
+  bool isMultiline = false;
+  int start = 0;
+  int end;
+
+  StringLexemeHelper(this.lexeme, this.isFirst, this.isLast) {
+    if (isFirst) {
+      isRaw = StringUtilities.startsWithChar(lexeme, 0x72);
+      if (isRaw) {
+        start++;
+      }
+      if (StringUtilities.startsWith3(lexeme, start, 0x27, 0x27, 0x27)) {
+        isSingleQuoted = true;
+        isMultiline = true;
+        start += 3;
+        start = _trimInitialWhitespace(start);
+      } else if (StringUtilities.startsWith3(lexeme, start, 0x22, 0x22, 0x22)) {
+        isSingleQuoted = false;
+        isMultiline = true;
+        start += 3;
+        start = _trimInitialWhitespace(start);
+      } else if (start < lexeme.length && lexeme.codeUnitAt(start) == 0x27) {
+        isSingleQuoted = true;
+        isMultiline = false;
+        start++;
+      } else if (start < lexeme.length && lexeme.codeUnitAt(start) == 0x22) {
+        isSingleQuoted = false;
+        isMultiline = false;
+        start++;
+      }
+    }
+    end = lexeme.length;
+    if (isLast) {
+      if (start + 3 <= end &&
+          (StringUtilities.endsWith3(lexeme, 0x22, 0x22, 0x22) ||
+              StringUtilities.endsWith3(lexeme, 0x27, 0x27, 0x27))) {
+        end -= 3;
+      } else if (start + 1 <= end &&
+          (StringUtilities.endsWithChar(lexeme, 0x22) ||
+              StringUtilities.endsWithChar(lexeme, 0x27))) {
+        end -= 1;
+      }
+    }
+  }
+
+  /**
+   * Given the [lexeme] for a multi-line string whose content begins at the
+   * given [start] index, return the index of the first character that is
+   * included in the value of the string. According to the specification:
+   *
+   * If the first line of a multiline string consists solely of the whitespace
+   * characters defined by the production WHITESPACE 20.1), possibly prefixed
+   * by \, then that line is ignored, including the new line at its end.
+   */
+  int _trimInitialWhitespace(int start) {
+    int length = lexeme.length;
+    int index = start;
+    while (index < length) {
+      int currentChar = lexeme.codeUnitAt(index);
+      if (currentChar == 0x0D) {
+        if (index + 1 < length && lexeme.codeUnitAt(index + 1) == 0x0A) {
+          return index + 2;
+        }
+        return index + 1;
+      } else if (currentChar == 0x0A) {
+        return index + 1;
+      } else if (currentChar == 0x5C) {
+        if (index + 1 >= length) {
+          return start;
+        }
+        currentChar = lexeme.codeUnitAt(index + 1);
+        if (currentChar != 0x0D &&
+            currentChar != 0x0A &&
+            currentChar != 0x09 &&
+            currentChar != 0x20) {
+          return start;
+        }
+      } else if (currentChar != 0x09 && currentChar != 0x20) {
+        return start;
+      }
+      index++;
+    }
+    return start;
+  }
+}
+
+/**
+ * A string literal expression.
+ *
+ * > stringLiteral ::=
+ * >     [SimpleStringLiteral]
+ * >   | [AdjacentStrings]
+ * >   | [StringInterpolation]
+ */
+abstract class StringLiteral extends Literal {
+  /**
+   * Return the value of the string literal, or `null` if the string is not a
+   * constant string without any string interpolation.
+   */
+  String get stringValue {
+    StringBuffer buffer = new StringBuffer();
+    try {
+      _appendStringValue(buffer);
+    } on IllegalArgumentException {
+      return null;
+    }
+    return buffer.toString();
+  }
+
+  /**
+   * Append the value of this string literal to the given [buffer]. Throw an
+   * [IllegalArgumentException] if the string is not a constant string without
+   * any string interpolation.
+   */
+  @deprecated // Use "this.stringValue"
+  void appendStringValue(StringBuffer buffer) => _appendStringValue(buffer);
+
+  /**
+   * Append the value of this string literal to the given [buffer]. Throw an
+   * [IllegalArgumentException] if the string is not a constant string without
+   * any string interpolation.
+   */
+  void _appendStringValue(StringBuffer buffer);
+}
+
+/**
+ * The invocation of a superclass' constructor from within a constructor's
+ * initialization list.
+ *
+ * > superInvocation ::=
+ * >     'super' ('.' [SimpleIdentifier])? [ArgumentList]
+ */
+class SuperConstructorInvocation extends ConstructorInitializer {
+  /**
+   * The token for the 'super' keyword.
+   */
+  Token superKeyword;
+
+  /**
+   * The token for the period before the name of the constructor that is being
+   * invoked, or `null` if the unnamed constructor is being invoked.
+   */
+  Token period;
+
+  /**
+   * The name of the constructor that is being invoked, or `null` if the unnamed
+   * constructor is being invoked.
+   */
+  SimpleIdentifier _constructorName;
+
+  /**
+   * The list of arguments to the constructor.
+   */
+  ArgumentList _argumentList;
+
+  /**
+   * The element associated with the constructor based on static type
+   * information, or `null` if the AST structure has not been resolved or if the
+   * constructor could not be resolved.
+   */
+  ConstructorElement staticElement;
+
+  /**
+   * Initialize a newly created super invocation to invoke the inherited
+   * constructor with the given name with the given arguments. The [period] and
+   * [constructorName] can be `null` if the constructor being invoked is the
+   * unnamed constructor.
+   */
+  SuperConstructorInvocation(this.superKeyword, this.period,
+      SimpleIdentifier constructorName, ArgumentList argumentList) {
+    _constructorName = _becomeParentOf(constructorName);
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  /**
+   * Return the list of arguments to the constructor.
+   */
+  ArgumentList get argumentList => _argumentList;
+
+  /**
+   * Set the list of arguments to the constructor to the given [argumentList].
+   */
+  void set argumentList(ArgumentList argumentList) {
+    _argumentList = _becomeParentOf(argumentList);
+  }
+
+  @override
+  Token get beginToken => superKeyword;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(superKeyword)
+    ..add(period)
+    ..add(_constructorName)
+    ..add(_argumentList);
+
+  /**
+   * Return the name of the constructor that is being invoked, or `null` if the
+   * unnamed constructor is being invoked.
+   */
+  SimpleIdentifier get constructorName => _constructorName;
+
+  /**
+   * Set the name of the constructor that is being invoked to the given
+   * [identifier].
+   */
+  void set constructorName(SimpleIdentifier identifier) {
+    _constructorName = _becomeParentOf(identifier);
+  }
+
+  @override
+  Token get endToken => _argumentList.endToken;
+
+  /**
+   * Return the token for the 'super' keyword.
+   */
+  @deprecated // Use "this.superKeyword"
+  Token get keyword => superKeyword;
+
+  /**
+   * Set the token for the 'super' keyword to the given [token].
+   */
+  @deprecated // Use "this.superKeyword"
+  set keyword(Token token) {
+    superKeyword = token;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitSuperConstructorInvocation(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_constructorName, visitor);
+    _safelyVisitChild(_argumentList, visitor);
+  }
+}
+
+/**
+ * A super expression.
+ *
+ * > superExpression ::=
+ * >     'super'
+ */
+class SuperExpression extends Expression {
+  /**
+   * The token representing the 'super' keyword.
+   */
+  Token superKeyword;
+
+  /**
+   * Initialize a newly created super expression.
+   */
+  SuperExpression(this.superKeyword);
+
+  @override
+  Token get beginToken => superKeyword;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(superKeyword);
+
+  @override
+  Token get endToken => superKeyword;
+
+  /**
+   * Return the token for the 'super' keyword.
+   */
+  @deprecated // Use "this.superKeyword"
+  Token get keyword => superKeyword;
+
+  /**
+   * Set the token for the 'super' keyword to the given [token].
+   */
+  @deprecated // Use "this.superKeyword"
+  set keyword(Token token) {
+    superKeyword = token;
+  }
+
+  @override
+  int get precedence => 16;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitSuperExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+}
+
+/**
+ * A case in a switch statement.
+ *
+ * > switchCase ::=
+ * >     [SimpleIdentifier]* 'case' [Expression] ':' [Statement]*
+ */
+class SwitchCase extends SwitchMember {
+  /**
+   * The expression controlling whether the statements will be executed.
+   */
+  Expression _expression;
+
+  /**
+   * Initialize a newly created switch case. The list of [labels] can be `null`
+   * if there are no labels.
+   */
+  SwitchCase(List<Label> labels, Token keyword, Expression expression,
+      Token colon, List<Statement> statements)
+      : super(labels, keyword, colon, statements) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..addAll(labels)
+    ..add(keyword)
+    ..add(_expression)
+    ..add(colon)
+    ..addAll(statements);
+
+  /**
+   * Return the expression controlling whether the statements will be executed.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression controlling whether the statements will be executed to
+   * the given [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitSwitchCase(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    labels.accept(visitor);
+    _safelyVisitChild(_expression, visitor);
+    statements.accept(visitor);
+  }
+}
+
+/**
+ * The default case in a switch statement.
+ *
+ * > switchDefault ::=
+ * >     [SimpleIdentifier]* 'default' ':' [Statement]*
+ */
+class SwitchDefault extends SwitchMember {
+  /**
+   * Initialize a newly created switch default. The list of [labels] can be
+   * `null` if there are no labels.
+   */
+  SwitchDefault(List<Label> labels, Token keyword, Token colon,
+      List<Statement> statements)
+      : super(labels, keyword, colon, statements);
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..addAll(labels)
+    ..add(keyword)
+    ..add(colon)
+    ..addAll(statements);
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitSwitchDefault(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    labels.accept(visitor);
+    statements.accept(visitor);
+  }
+}
+
+/**
+ * An element within a switch statement.
+ *
+ * > switchMember ::=
+ * >     switchCase
+ * >   | switchDefault
+ */
+abstract class SwitchMember extends AstNode {
+  /**
+   * The labels associated with the switch member.
+   */
+  NodeList<Label> _labels;
+
+  /**
+   * The token representing the 'case' or 'default' keyword.
+   */
+  Token keyword;
+
+  /**
+   * The colon separating the keyword or the expression from the statements.
+   */
+  Token colon;
+
+  /**
+   * The statements that will be executed if this switch member is selected.
+   */
+  NodeList<Statement> _statements;
+
+  /**
+   * Initialize a newly created switch member. The list of [labels] can be
+   * `null` if there are no labels.
+   */
+  SwitchMember(List<Label> labels, this.keyword, this.colon,
+      List<Statement> statements) {
+    _labels = new NodeList<Label>(this, labels);
+    _statements = new NodeList<Statement>(this, statements);
+  }
+
+  @override
+  Token get beginToken {
+    if (!_labels.isEmpty) {
+      return _labels.beginToken;
+    }
+    return keyword;
+  }
+
+  @override
+  Token get endToken {
+    if (!_statements.isEmpty) {
+      return _statements.endToken;
+    }
+    return colon;
+  }
+
+  /**
+   * Return the labels associated with the switch member.
+   */
+  NodeList<Label> get labels => _labels;
+
+  /**
+   * Return the statements that will be executed if this switch member is
+   * selected.
+   */
+  NodeList<Statement> get statements => _statements;
+}
+
+/**
+ * A switch statement.
+ *
+ * > switchStatement ::=
+ * >     'switch' '(' [Expression] ')' '{' [SwitchCase]* [SwitchDefault]? '}'
+ */
+class SwitchStatement extends Statement {
+  /**
+   * The token representing the 'switch' keyword.
+   */
+  Token switchKeyword;
+
+  /**
+   * The left parenthesis.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The expression used to determine which of the switch members will be
+   * selected.
+   */
+  Expression _expression;
+
+  /**
+   * The right parenthesis.
+   */
+  Token rightParenthesis;
+
+  /**
+   * The left curly bracket.
+   */
+  Token leftBracket;
+
+  /**
+   * The switch members that can be selected by the expression.
+   */
+  NodeList<SwitchMember> _members;
+
+  /**
+   * The right curly bracket.
+   */
+  Token rightBracket;
+
+  /**
+   * Initialize a newly created switch statement. The list of [members] can be
+   * `null` if there are no switch members.
+   */
+  SwitchStatement(this.switchKeyword, this.leftParenthesis,
+      Expression expression, this.rightParenthesis, this.leftBracket,
+      List<SwitchMember> members, this.rightBracket) {
+    _expression = _becomeParentOf(expression);
+    _members = new NodeList<SwitchMember>(this, members);
+  }
+
+  @override
+  Token get beginToken => switchKeyword;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(switchKeyword)
+    ..add(leftParenthesis)
+    ..add(_expression)
+    ..add(rightParenthesis)
+    ..add(leftBracket)
+    ..addAll(_members)
+    ..add(rightBracket);
+
+  @override
+  Token get endToken => rightBracket;
+
+  /**
+   * Return the expression used to determine which of the switch members will be
+   * selected.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression used to determine which of the switch members will be
+   * selected to the given [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  /**
+   * Return the token representing the 'switch' keyword.
+   */
+  @deprecated // Use "this.switchKeyword"
+  Token get keyword => switchKeyword;
+
+  /**
+   * Set the token representing the 'switch' keyword to the given [token].
+   */
+  @deprecated // Use "this.switchKeyword"
+  set keyword(Token token) {
+    switchKeyword = token;
+  }
+
+  /**
+   * Return the switch members that can be selected by the expression.
+   */
+  NodeList<SwitchMember> get members => _members;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitSwitchStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+    _members.accept(visitor);
+  }
+}
+
+/**
+ * A symbol literal expression.
+ *
+ * > symbolLiteral ::=
+ * >     '#' (operator | (identifier ('.' identifier)*))
+ */
+class SymbolLiteral extends Literal {
+  /**
+   * The token introducing the literal.
+   */
+  Token poundSign;
+
+  /**
+   * The components of the literal.
+   */
+  final List<Token> components;
+
+  /**
+   * Initialize a newly created symbol literal.
+   */
+  SymbolLiteral(this.poundSign, this.components);
+
+  @override
+  Token get beginToken => poundSign;
+
+  /**
+   * TODO(paulberry): add "." tokens.
+   */
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(poundSign)
+    ..addAll(components);
+
+  @override
+  Token get endToken => components[components.length - 1];
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitSymbolLiteral(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+}
+
+/**
+ * A this expression.
+ *
+ * > thisExpression ::=
+ * >     'this'
+ */
+class ThisExpression extends Expression {
+  /**
+   * The token representing the 'this' keyword.
+   */
+  Token thisKeyword;
+
+  /**
+   * Initialize a newly created this expression.
+   */
+  ThisExpression(this.thisKeyword);
+
+  @override
+  Token get beginToken => thisKeyword;
+
+  @override
+  Iterable get childEntities => new ChildEntities()..add(thisKeyword);
+
+  @override
+  Token get endToken => thisKeyword;
+
+  /**
+   * Return the token representing the 'this' keyword.
+   */
+  @deprecated // Use "this.thisKeyword"
+  Token get keyword => thisKeyword;
+
+  /**
+   * Set the token representing the 'this' keyword to the given [token].
+   */
+  @deprecated // Use "this.thisKeyword"
+  set keyword(Token token) {
+    thisKeyword = token;
+  }
+
+  @override
+  int get precedence => 16;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitThisExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    // There are no children to visit.
+  }
+}
+
+/**
+ * A throw expression.
+ *
+ * > throwExpression ::=
+ * >     'throw' [Expression]
+ */
+class ThrowExpression extends Expression {
+  /**
+   * The token representing the 'throw' keyword.
+   */
+  Token throwKeyword;
+
+  /**
+   * The expression computing the exception to be thrown.
+   */
+  Expression _expression;
+
+  /**
+   * Initialize a newly created throw expression.
+   */
+  ThrowExpression(this.throwKeyword, Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get beginToken => throwKeyword;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(throwKeyword)..add(_expression);
+
+  @override
+  Token get endToken {
+    if (_expression != null) {
+      return _expression.endToken;
+    }
+    return throwKeyword;
+  }
+
+  /**
+   * Return the expression computing the exception to be thrown.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression computing the exception to be thrown to the given
+   * [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  /**
+   * Return the token representing the 'throw' keyword.
+   */
+  @deprecated // Use "this.throwKeyword"
+  Token get keyword => throwKeyword;
+
+  /**
+   * Set the token representing the 'throw' keyword to the given [token].
+   */
+  @deprecated // Use "this.throwKeyword"
+  set keyword(Token token) {
+    throwKeyword = token;
+  }
+
+  @override
+  int get precedence => 0;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitThrowExpression(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+  }
+}
+
+/**
+ * The declaration of one or more top-level variables of the same type.
+ *
+ * > topLevelVariableDeclaration ::=
+ * >     ('final' | 'const') type? staticFinalDeclarationList ';'
+ * >   | variableDeclaration ';'
+ */
+class TopLevelVariableDeclaration extends CompilationUnitMember {
+  /**
+   * The top-level variables being declared.
+   */
+  VariableDeclarationList _variableList;
+
+  /**
+   * The semicolon terminating the declaration.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created top-level variable declaration. Either or both
+   * of the [comment] and [metadata] can be `null` if the variable does not have
+   * the corresponding attribute.
+   */
+  TopLevelVariableDeclaration(Comment comment, List<Annotation> metadata,
+      VariableDeclarationList variableList, this.semicolon)
+      : super(comment, metadata) {
+    _variableList = _becomeParentOf(variableList);
+  }
+
+  @override
+  Iterable get childEntities =>
+      super._childEntities..add(_variableList)..add(semicolon);
+
+  @override
+  Element get element => null;
+
+  @override
+  Token get endToken => semicolon;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata => _variableList.beginToken;
+
+  /**
+   * Return the top-level variables being declared.
+   */
+  VariableDeclarationList get variables => _variableList;
+
+  /**
+   * Set the top-level variables being declared to the given list of
+   * [variables].
+   */
+  void set variables(VariableDeclarationList variables) {
+    _variableList = _becomeParentOf(variables);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitTopLevelVariableDeclaration(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_variableList, visitor);
+  }
+}
+
+/**
+ * A visitor used to write a source representation of a visited AST node (and
+ * all of it's children) to a writer.
+ */
+class ToSourceVisitor implements AstVisitor<Object> {
+  /**
+   * The writer to which the source is to be written.
+   */
+  final PrintWriter _writer;
+
+  /**
+   * Initialize a newly created visitor to write source code representing the
+   * visited nodes to the given [writer].
+   */
+  ToSourceVisitor(this._writer);
+
+  @override
+  Object visitAdjacentStrings(AdjacentStrings node) {
+    _visitNodeListWithSeparator(node.strings, " ");
+    return null;
+  }
+
+  @override
+  Object visitAnnotation(Annotation node) {
+    _writer.print('@');
+    _visitNode(node.name);
+    _visitNodeWithPrefix(".", node.constructorName);
+    _visitNode(node.arguments);
+    return null;
+  }
+
+  @override
+  Object visitArgumentList(ArgumentList node) {
+    _writer.print('(');
+    _visitNodeListWithSeparator(node.arguments, ", ");
+    _writer.print(')');
+    return null;
+  }
+
+  @override
+  Object visitAsExpression(AsExpression node) {
+    _visitNode(node.expression);
+    _writer.print(" as ");
+    _visitNode(node.type);
+    return null;
+  }
+
+  @override
+  Object visitAssertStatement(AssertStatement node) {
+    _writer.print("assert (");
+    _visitNode(node.condition);
+    _writer.print(");");
+    return null;
+  }
+
+  @override
+  Object visitAssignmentExpression(AssignmentExpression node) {
+    _visitNode(node.leftHandSide);
+    _writer.print(' ');
+    _writer.print(node.operator.lexeme);
+    _writer.print(' ');
+    _visitNode(node.rightHandSide);
+    return null;
+  }
+
+  @override
+  Object visitAwaitExpression(AwaitExpression node) {
+    _writer.print("await ");
+    _visitNode(node.expression);
+    _writer.print(";");
+    return null;
+  }
+
+  @override
+  Object visitBinaryExpression(BinaryExpression node) {
+    _visitNode(node.leftOperand);
+    _writer.print(' ');
+    _writer.print(node.operator.lexeme);
+    _writer.print(' ');
+    _visitNode(node.rightOperand);
+    return null;
+  }
+
+  @override
+  Object visitBlock(Block node) {
+    _writer.print('{');
+    _visitNodeListWithSeparator(node.statements, " ");
+    _writer.print('}');
+    return null;
+  }
+
+  @override
+  Object visitBlockFunctionBody(BlockFunctionBody node) {
+    Token keyword = node.keyword;
+    if (keyword != null) {
+      _writer.print(keyword.lexeme);
+      if (node.star != null) {
+        _writer.print('*');
+      }
+      _writer.print(' ');
+    }
+    _visitNode(node.block);
+    return null;
+  }
+
+  @override
+  Object visitBooleanLiteral(BooleanLiteral node) {
+    _writer.print(node.literal.lexeme);
+    return null;
+  }
+
+  @override
+  Object visitBreakStatement(BreakStatement node) {
+    _writer.print("break");
+    _visitNodeWithPrefix(" ", node.label);
+    _writer.print(";");
+    return null;
+  }
+
+  @override
+  Object visitCascadeExpression(CascadeExpression node) {
+    _visitNode(node.target);
+    _visitNodeList(node.cascadeSections);
+    return null;
+  }
+
+  @override
+  Object visitCatchClause(CatchClause node) {
+    _visitNodeWithPrefix("on ", node.exceptionType);
+    if (node.catchKeyword != null) {
+      if (node.exceptionType != null) {
+        _writer.print(' ');
+      }
+      _writer.print("catch (");
+      _visitNode(node.exceptionParameter);
+      _visitNodeWithPrefix(", ", node.stackTraceParameter);
+      _writer.print(") ");
+    } else {
+      _writer.print(" ");
+    }
+    _visitNode(node.body);
+    return null;
+  }
+
+  @override
+  Object visitClassDeclaration(ClassDeclaration node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _visitTokenWithSuffix(node.abstractKeyword, " ");
+    _writer.print("class ");
+    _visitNode(node.name);
+    _visitNode(node.typeParameters);
+    _visitNodeWithPrefix(" ", node.extendsClause);
+    _visitNodeWithPrefix(" ", node.withClause);
+    _visitNodeWithPrefix(" ", node.implementsClause);
+    _writer.print(" {");
+    _visitNodeListWithSeparator(node.members, " ");
+    _writer.print("}");
+    return null;
+  }
+
+  @override
+  Object visitClassTypeAlias(ClassTypeAlias node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    if (node.abstractKeyword != null) {
+      _writer.print("abstract ");
+    }
+    _writer.print("class ");
+    _visitNode(node.name);
+    _visitNode(node.typeParameters);
+    _writer.print(" = ");
+    _visitNode(node.superclass);
+    _visitNodeWithPrefix(" ", node.withClause);
+    _visitNodeWithPrefix(" ", node.implementsClause);
+    _writer.print(";");
+    return null;
+  }
+
+  @override
+  Object visitComment(Comment node) => null;
+
+  @override
+  Object visitCommentReference(CommentReference node) => null;
+
+  @override
+  Object visitCompilationUnit(CompilationUnit node) {
+    ScriptTag scriptTag = node.scriptTag;
+    NodeList<Directive> directives = node.directives;
+    _visitNode(scriptTag);
+    String prefix = scriptTag == null ? "" : " ";
+    _visitNodeListWithSeparatorAndPrefix(prefix, directives, " ");
+    prefix = scriptTag == null && directives.isEmpty ? "" : " ";
+    _visitNodeListWithSeparatorAndPrefix(prefix, node.declarations, " ");
+    return null;
+  }
+
+  @override
+  Object visitConditionalExpression(ConditionalExpression node) {
+    _visitNode(node.condition);
+    _writer.print(" ? ");
+    _visitNode(node.thenExpression);
+    _writer.print(" : ");
+    _visitNode(node.elseExpression);
+    return null;
+  }
+
+  @override
+  Object visitConstructorDeclaration(ConstructorDeclaration node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _visitTokenWithSuffix(node.externalKeyword, " ");
+    _visitTokenWithSuffix(node.constKeyword, " ");
+    _visitTokenWithSuffix(node.factoryKeyword, " ");
+    _visitNode(node.returnType);
+    _visitNodeWithPrefix(".", node.name);
+    _visitNode(node.parameters);
+    _visitNodeListWithSeparatorAndPrefix(" : ", node.initializers, ", ");
+    _visitNodeWithPrefix(" = ", node.redirectedConstructor);
+    _visitFunctionWithPrefix(" ", node.body);
+    return null;
+  }
+
+  @override
+  Object visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
+    _visitTokenWithSuffix(node.thisKeyword, ".");
+    _visitNode(node.fieldName);
+    _writer.print(" = ");
+    _visitNode(node.expression);
+    return null;
+  }
+
+  @override
+  Object visitConstructorName(ConstructorName node) {
+    _visitNode(node.type);
+    _visitNodeWithPrefix(".", node.name);
+    return null;
+  }
+
+  @override
+  Object visitContinueStatement(ContinueStatement node) {
+    _writer.print("continue");
+    _visitNodeWithPrefix(" ", node.label);
+    _writer.print(";");
+    return null;
+  }
+
+  @override
+  Object visitDeclaredIdentifier(DeclaredIdentifier node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _visitTokenWithSuffix(node.keyword, " ");
+    _visitNodeWithSuffix(node.type, " ");
+    _visitNode(node.identifier);
+    return null;
+  }
+
+  @override
+  Object visitDefaultFormalParameter(DefaultFormalParameter node) {
+    _visitNode(node.parameter);
+    if (node.separator != null) {
+      _writer.print(" ");
+      _writer.print(node.separator.lexeme);
+      _visitNodeWithPrefix(" ", node.defaultValue);
+    }
+    return null;
+  }
+
+  @override
+  Object visitDoStatement(DoStatement node) {
+    _writer.print("do ");
+    _visitNode(node.body);
+    _writer.print(" while (");
+    _visitNode(node.condition);
+    _writer.print(");");
+    return null;
+  }
+
+  @override
+  Object visitDoubleLiteral(DoubleLiteral node) {
+    _writer.print(node.literal.lexeme);
+    return null;
+  }
+
+  @override
+  Object visitEmptyFunctionBody(EmptyFunctionBody node) {
+    _writer.print(';');
+    return null;
+  }
+
+  @override
+  Object visitEmptyStatement(EmptyStatement node) {
+    _writer.print(';');
+    return null;
+  }
+
+  @override
+  Object visitEnumConstantDeclaration(EnumConstantDeclaration node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _visitNode(node.name);
+    return null;
+  }
+
+  @override
+  Object visitEnumDeclaration(EnumDeclaration node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _writer.print("enum ");
+    _visitNode(node.name);
+    _writer.print(" {");
+    _visitNodeListWithSeparator(node.constants, ", ");
+    _writer.print("}");
+    return null;
+  }
+
+  @override
+  Object visitExportDirective(ExportDirective node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _writer.print("export ");
+    _visitNode(node.uri);
+    _visitNodeListWithSeparatorAndPrefix(" ", node.combinators, " ");
+    _writer.print(';');
+    return null;
+  }
+
+  @override
+  Object visitExpressionFunctionBody(ExpressionFunctionBody node) {
+    Token keyword = node.keyword;
+    if (keyword != null) {
+      _writer.print(keyword.lexeme);
+      _writer.print(' ');
+    }
+    _writer.print("=> ");
+    _visitNode(node.expression);
+    if (node.semicolon != null) {
+      _writer.print(';');
+    }
+    return null;
+  }
+
+  @override
+  Object visitExpressionStatement(ExpressionStatement node) {
+    _visitNode(node.expression);
+    _writer.print(';');
+    return null;
+  }
+
+  @override
+  Object visitExtendsClause(ExtendsClause node) {
+    _writer.print("extends ");
+    _visitNode(node.superclass);
+    return null;
+  }
+
+  @override
+  Object visitFieldDeclaration(FieldDeclaration node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _visitTokenWithSuffix(node.staticKeyword, " ");
+    _visitNode(node.fields);
+    _writer.print(";");
+    return null;
+  }
+
+  @override
+  Object visitFieldFormalParameter(FieldFormalParameter node) {
+    _visitTokenWithSuffix(node.keyword, " ");
+    _visitNodeWithSuffix(node.type, " ");
+    _writer.print("this.");
+    _visitNode(node.identifier);
+    _visitNode(node.typeParameters);
+    _visitNode(node.parameters);
+    return null;
+  }
+
+  @override
+  Object visitForEachStatement(ForEachStatement node) {
+    DeclaredIdentifier loopVariable = node.loopVariable;
+    if (node.awaitKeyword != null) {
+      _writer.print("await ");
+    }
+    _writer.print("for (");
+    if (loopVariable == null) {
+      _visitNode(node.identifier);
+    } else {
+      _visitNode(loopVariable);
+    }
+    _writer.print(" in ");
+    _visitNode(node.iterable);
+    _writer.print(") ");
+    _visitNode(node.body);
+    return null;
+  }
+
+  @override
+  Object visitFormalParameterList(FormalParameterList node) {
+    String groupEnd = null;
+    _writer.print('(');
+    NodeList<FormalParameter> parameters = node.parameters;
+    int size = parameters.length;
+    for (int i = 0; i < size; i++) {
+      FormalParameter parameter = parameters[i];
+      if (i > 0) {
+        _writer.print(", ");
+      }
+      if (groupEnd == null && parameter is DefaultFormalParameter) {
+        if (parameter.kind == ParameterKind.NAMED) {
+          groupEnd = "}";
+          _writer.print('{');
+        } else {
+          groupEnd = "]";
+          _writer.print('[');
+        }
+      }
+      parameter.accept(this);
+    }
+    if (groupEnd != null) {
+      _writer.print(groupEnd);
+    }
+    _writer.print(')');
+    return null;
+  }
+
+  @override
+  Object visitForStatement(ForStatement node) {
+    Expression initialization = node.initialization;
+    _writer.print("for (");
+    if (initialization != null) {
+      _visitNode(initialization);
+    } else {
+      _visitNode(node.variables);
+    }
+    _writer.print(";");
+    _visitNodeWithPrefix(" ", node.condition);
+    _writer.print(";");
+    _visitNodeListWithSeparatorAndPrefix(" ", node.updaters, ", ");
+    _writer.print(") ");
+    _visitNode(node.body);
+    return null;
+  }
+
+  @override
+  Object visitFunctionDeclaration(FunctionDeclaration node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _visitTokenWithSuffix(node.externalKeyword, " ");
+    _visitNodeWithSuffix(node.returnType, " ");
+    _visitTokenWithSuffix(node.propertyKeyword, " ");
+    _visitNode(node.name);
+    _visitNode(node.functionExpression);
+    return null;
+  }
+
+  @override
+  Object visitFunctionDeclarationStatement(FunctionDeclarationStatement node) {
+    _visitNode(node.functionDeclaration);
+    return null;
+  }
+
+  @override
+  Object visitFunctionExpression(FunctionExpression node) {
+    _visitNode(node.typeParameters);
+    _visitNode(node.parameters);
+    if (node.body is! EmptyFunctionBody) {
+      _writer.print(' ');
+    }
+    _visitNode(node.body);
+    return null;
+  }
+
+  @override
+  Object visitFunctionExpressionInvocation(FunctionExpressionInvocation node) {
+    _visitNode(node.function);
+    _visitNode(node.typeArguments);
+    _visitNode(node.argumentList);
+    return null;
+  }
+
+  @override
+  Object visitFunctionTypeAlias(FunctionTypeAlias node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _writer.print("typedef ");
+    _visitNodeWithSuffix(node.returnType, " ");
+    _visitNode(node.name);
+    _visitNode(node.typeParameters);
+    _visitNode(node.parameters);
+    _writer.print(";");
+    return null;
+  }
+
+  @override
+  Object visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
+    _visitNodeWithSuffix(node.returnType, " ");
+    _visitNode(node.identifier);
+    _visitNode(node.typeParameters);
+    _visitNode(node.parameters);
+    return null;
+  }
+
+  @override
+  Object visitHideCombinator(HideCombinator node) {
+    _writer.print("hide ");
+    _visitNodeListWithSeparator(node.hiddenNames, ", ");
+    return null;
+  }
+
+  @override
+  Object visitIfStatement(IfStatement node) {
+    _writer.print("if (");
+    _visitNode(node.condition);
+    _writer.print(") ");
+    _visitNode(node.thenStatement);
+    _visitNodeWithPrefix(" else ", node.elseStatement);
+    return null;
+  }
+
+  @override
+  Object visitImplementsClause(ImplementsClause node) {
+    _writer.print("implements ");
+    _visitNodeListWithSeparator(node.interfaces, ", ");
+    return null;
+  }
+
+  @override
+  Object visitImportDirective(ImportDirective node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _writer.print("import ");
+    _visitNode(node.uri);
+    if (node.deferredKeyword != null) {
+      _writer.print(" deferred");
+    }
+    _visitNodeWithPrefix(" as ", node.prefix);
+    _visitNodeListWithSeparatorAndPrefix(" ", node.combinators, " ");
+    _writer.print(';');
+    return null;
+  }
+
+  @override
+  Object visitIndexExpression(IndexExpression node) {
+    if (node.isCascaded) {
+      _writer.print("..");
+    } else {
+      _visitNode(node.target);
+    }
+    _writer.print('[');
+    _visitNode(node.index);
+    _writer.print(']');
+    return null;
+  }
+
+  @override
+  Object visitInstanceCreationExpression(InstanceCreationExpression node) {
+    _visitTokenWithSuffix(node.keyword, " ");
+    _visitNode(node.constructorName);
+    _visitNode(node.argumentList);
+    return null;
+  }
+
+  @override
+  Object visitIntegerLiteral(IntegerLiteral node) {
+    _writer.print(node.literal.lexeme);
+    return null;
+  }
+
+  @override
+  Object visitInterpolationExpression(InterpolationExpression node) {
+    if (node.rightBracket != null) {
+      _writer.print("\${");
+      _visitNode(node.expression);
+      _writer.print("}");
+    } else {
+      _writer.print("\$");
+      _visitNode(node.expression);
+    }
+    return null;
+  }
+
+  @override
+  Object visitInterpolationString(InterpolationString node) {
+    _writer.print(node.contents.lexeme);
+    return null;
+  }
+
+  @override
+  Object visitIsExpression(IsExpression node) {
+    _visitNode(node.expression);
+    if (node.notOperator == null) {
+      _writer.print(" is ");
+    } else {
+      _writer.print(" is! ");
+    }
+    _visitNode(node.type);
+    return null;
+  }
+
+  @override
+  Object visitLabel(Label node) {
+    _visitNode(node.label);
+    _writer.print(":");
+    return null;
+  }
+
+  @override
+  Object visitLabeledStatement(LabeledStatement node) {
+    _visitNodeListWithSeparatorAndSuffix(node.labels, " ", " ");
+    _visitNode(node.statement);
+    return null;
+  }
+
+  @override
+  Object visitLibraryDirective(LibraryDirective node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _writer.print("library ");
+    _visitNode(node.name);
+    _writer.print(';');
+    return null;
+  }
+
+  @override
+  Object visitLibraryIdentifier(LibraryIdentifier node) {
+    _writer.print(node.name);
+    return null;
+  }
+
+  @override
+  Object visitListLiteral(ListLiteral node) {
+    if (node.constKeyword != null) {
+      _writer.print(node.constKeyword.lexeme);
+      _writer.print(' ');
+    }
+    _visitNodeWithSuffix(node.typeArguments, " ");
+    _writer.print("[");
+    _visitNodeListWithSeparator(node.elements, ", ");
+    _writer.print("]");
+    return null;
+  }
+
+  @override
+  Object visitMapLiteral(MapLiteral node) {
+    if (node.constKeyword != null) {
+      _writer.print(node.constKeyword.lexeme);
+      _writer.print(' ');
+    }
+    _visitNodeWithSuffix(node.typeArguments, " ");
+    _writer.print("{");
+    _visitNodeListWithSeparator(node.entries, ", ");
+    _writer.print("}");
+    return null;
+  }
+
+  @override
+  Object visitMapLiteralEntry(MapLiteralEntry node) {
+    _visitNode(node.key);
+    _writer.print(" : ");
+    _visitNode(node.value);
+    return null;
+  }
+
+  @override
+  Object visitMethodDeclaration(MethodDeclaration node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _visitTokenWithSuffix(node.externalKeyword, " ");
+    _visitTokenWithSuffix(node.modifierKeyword, " ");
+    _visitNodeWithSuffix(node.returnType, " ");
+    _visitTokenWithSuffix(node.propertyKeyword, " ");
+    _visitTokenWithSuffix(node.operatorKeyword, " ");
+    _visitNode(node.name);
+    if (!node.isGetter) {
+      _visitNode(node.typeParameters);
+      _visitNode(node.parameters);
+    }
+    _visitFunctionWithPrefix(" ", node.body);
+    return null;
+  }
+
+  @override
+  Object visitMethodInvocation(MethodInvocation node) {
+    if (node.isCascaded) {
+      _writer.print("..");
+    } else {
+      if (node.target != null) {
+        node.target.accept(this);
+        _writer.print(node.operator.lexeme);
+      }
+    }
+    _visitNode(node.methodName);
+    _visitNode(node.typeArguments);
+    _visitNode(node.argumentList);
+    return null;
+  }
+
+  @override
+  Object visitNamedExpression(NamedExpression node) {
+    _visitNode(node.name);
+    _visitNodeWithPrefix(" ", node.expression);
+    return null;
+  }
+
+  @override
+  Object visitNativeClause(NativeClause node) {
+    _writer.print("native ");
+    _visitNode(node.name);
+    return null;
+  }
+
+  @override
+  Object visitNativeFunctionBody(NativeFunctionBody node) {
+    _writer.print("native ");
+    _visitNode(node.stringLiteral);
+    _writer.print(';');
+    return null;
+  }
+
+  @override
+  Object visitNullLiteral(NullLiteral node) {
+    _writer.print("null");
+    return null;
+  }
+
+  @override
+  Object visitParenthesizedExpression(ParenthesizedExpression node) {
+    _writer.print('(');
+    _visitNode(node.expression);
+    _writer.print(')');
+    return null;
+  }
+
+  @override
+  Object visitPartDirective(PartDirective node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _writer.print("part ");
+    _visitNode(node.uri);
+    _writer.print(';');
+    return null;
+  }
+
+  @override
+  Object visitPartOfDirective(PartOfDirective node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _writer.print("part of ");
+    _visitNode(node.libraryName);
+    _writer.print(';');
+    return null;
+  }
+
+  @override
+  Object visitPostfixExpression(PostfixExpression node) {
+    _visitNode(node.operand);
+    _writer.print(node.operator.lexeme);
+    return null;
+  }
+
+  @override
+  Object visitPrefixedIdentifier(PrefixedIdentifier node) {
+    _visitNode(node.prefix);
+    _writer.print('.');
+    _visitNode(node.identifier);
+    return null;
+  }
+
+  @override
+  Object visitPrefixExpression(PrefixExpression node) {
+    _writer.print(node.operator.lexeme);
+    _visitNode(node.operand);
+    return null;
+  }
+
+  @override
+  Object visitPropertyAccess(PropertyAccess node) {
+    if (node.isCascaded) {
+      _writer.print("..");
+    } else {
+      _visitNode(node.target);
+      _writer.print(node.operator.lexeme);
+    }
+    _visitNode(node.propertyName);
+    return null;
+  }
+
+  @override
+  Object visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) {
+    _writer.print("this");
+    _visitNodeWithPrefix(".", node.constructorName);
+    _visitNode(node.argumentList);
+    return null;
+  }
+
+  @override
+  Object visitRethrowExpression(RethrowExpression node) {
+    _writer.print("rethrow");
+    return null;
+  }
+
+  @override
+  Object visitReturnStatement(ReturnStatement node) {
+    Expression expression = node.expression;
+    if (expression == null) {
+      _writer.print("return;");
+    } else {
+      _writer.print("return ");
+      expression.accept(this);
+      _writer.print(";");
+    }
+    return null;
+  }
+
+  @override
+  Object visitScriptTag(ScriptTag node) {
+    _writer.print(node.scriptTag.lexeme);
+    return null;
+  }
+
+  @override
+  Object visitShowCombinator(ShowCombinator node) {
+    _writer.print("show ");
+    _visitNodeListWithSeparator(node.shownNames, ", ");
+    return null;
+  }
+
+  @override
+  Object visitSimpleFormalParameter(SimpleFormalParameter node) {
+    _visitTokenWithSuffix(node.keyword, " ");
+    _visitNodeWithSuffix(node.type, " ");
+    _visitNode(node.identifier);
+    return null;
+  }
+
+  @override
+  Object visitSimpleIdentifier(SimpleIdentifier node) {
+    _writer.print(node.token.lexeme);
+    return null;
+  }
+
+  @override
+  Object visitSimpleStringLiteral(SimpleStringLiteral node) {
+    _writer.print(node.literal.lexeme);
+    return null;
+  }
+
+  @override
+  Object visitStringInterpolation(StringInterpolation node) {
+    _visitNodeList(node.elements);
+    return null;
+  }
+
+  @override
+  Object visitSuperConstructorInvocation(SuperConstructorInvocation node) {
+    _writer.print("super");
+    _visitNodeWithPrefix(".", node.constructorName);
+    _visitNode(node.argumentList);
+    return null;
+  }
+
+  @override
+  Object visitSuperExpression(SuperExpression node) {
+    _writer.print("super");
+    return null;
+  }
+
+  @override
+  Object visitSwitchCase(SwitchCase node) {
+    _visitNodeListWithSeparatorAndSuffix(node.labels, " ", " ");
+    _writer.print("case ");
+    _visitNode(node.expression);
+    _writer.print(": ");
+    _visitNodeListWithSeparator(node.statements, " ");
+    return null;
+  }
+
+  @override
+  Object visitSwitchDefault(SwitchDefault node) {
+    _visitNodeListWithSeparatorAndSuffix(node.labels, " ", " ");
+    _writer.print("default: ");
+    _visitNodeListWithSeparator(node.statements, " ");
+    return null;
+  }
+
+  @override
+  Object visitSwitchStatement(SwitchStatement node) {
+    _writer.print("switch (");
+    _visitNode(node.expression);
+    _writer.print(") {");
+    _visitNodeListWithSeparator(node.members, " ");
+    _writer.print("}");
+    return null;
+  }
+
+  @override
+  Object visitSymbolLiteral(SymbolLiteral node) {
+    _writer.print("#");
+    List<Token> components = node.components;
+    for (int i = 0; i < components.length; i++) {
+      if (i > 0) {
+        _writer.print(".");
+      }
+      _writer.print(components[i].lexeme);
+    }
+    return null;
+  }
+
+  @override
+  Object visitThisExpression(ThisExpression node) {
+    _writer.print("this");
+    return null;
+  }
+
+  @override
+  Object visitThrowExpression(ThrowExpression node) {
+    _writer.print("throw ");
+    _visitNode(node.expression);
+    return null;
+  }
+
+  @override
+  Object visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
+    _visitNodeWithSuffix(node.variables, ";");
+    return null;
+  }
+
+  @override
+  Object visitTryStatement(TryStatement node) {
+    _writer.print("try ");
+    _visitNode(node.body);
+    _visitNodeListWithSeparatorAndPrefix(" ", node.catchClauses, " ");
+    _visitNodeWithPrefix(" finally ", node.finallyBlock);
+    return null;
+  }
+
+  @override
+  Object visitTypeArgumentList(TypeArgumentList node) {
+    _writer.print('<');
+    _visitNodeListWithSeparator(node.arguments, ", ");
+    _writer.print('>');
+    return null;
+  }
+
+  @override
+  Object visitTypeName(TypeName node) {
+    _visitNode(node.name);
+    _visitNode(node.typeArguments);
+    return null;
+  }
+
+  @override
+  Object visitTypeParameter(TypeParameter node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _visitNode(node.name);
+    _visitNodeWithPrefix(" extends ", node.bound);
+    return null;
+  }
+
+  @override
+  Object visitTypeParameterList(TypeParameterList node) {
+    _writer.print('<');
+    _visitNodeListWithSeparator(node.typeParameters, ", ");
+    _writer.print('>');
+    return null;
+  }
+
+  @override
+  Object visitVariableDeclaration(VariableDeclaration node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _visitNode(node.name);
+    _visitNodeWithPrefix(" = ", node.initializer);
+    return null;
+  }
+
+  @override
+  Object visitVariableDeclarationList(VariableDeclarationList node) {
+    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
+    _visitTokenWithSuffix(node.keyword, " ");
+    _visitNodeWithSuffix(node.type, " ");
+    _visitNodeListWithSeparator(node.variables, ", ");
+    return null;
+  }
+
+  @override
+  Object visitVariableDeclarationStatement(VariableDeclarationStatement node) {
+    _visitNode(node.variables);
+    _writer.print(";");
+    return null;
+  }
+
+  @override
+  Object visitWhileStatement(WhileStatement node) {
+    _writer.print("while (");
+    _visitNode(node.condition);
+    _writer.print(") ");
+    _visitNode(node.body);
+    return null;
+  }
+
+  @override
+  Object visitWithClause(WithClause node) {
+    _writer.print("with ");
+    _visitNodeListWithSeparator(node.mixinTypes, ", ");
+    return null;
+  }
+
+  @override
+  Object visitYieldStatement(YieldStatement node) {
+    if (node.star != null) {
+      _writer.print("yield* ");
+    } else {
+      _writer.print("yield ");
+    }
+    _visitNode(node.expression);
+    _writer.print(";");
+    return null;
+  }
+
+  /**
+   * Visit the given function [body], printing the [prefix] before if the body
+   * is not empty.
+   */
+  void _visitFunctionWithPrefix(String prefix, FunctionBody body) {
+    if (body is! EmptyFunctionBody) {
+      _writer.print(prefix);
+    }
+    _visitNode(body);
+  }
+
+  /**
+   * Safely visit the given [node].
+   */
+  void _visitNode(AstNode node) {
+    if (node != null) {
+      node.accept(this);
+    }
+  }
+
+  /**
+   * Print a list of [nodes] without any separation.
+   */
+  void _visitNodeList(NodeList<AstNode> nodes) {
+    _visitNodeListWithSeparator(nodes, "");
+  }
+
+  /**
+   * Print a list of [nodes], separated by the given [separator].
+   */
+  void _visitNodeListWithSeparator(NodeList<AstNode> nodes, String separator) {
+    if (nodes != null) {
+      int size = nodes.length;
+      for (int i = 0; i < size; i++) {
+        if (i > 0) {
+          _writer.print(separator);
+        }
+        nodes[i].accept(this);
+      }
+    }
+  }
+
+  /**
+   * Print a list of [nodes], prefixed by the given [prefix] if the list is not
+   * empty, and separated by the given [separator].
+   */
+  void _visitNodeListWithSeparatorAndPrefix(
+      String prefix, NodeList<AstNode> nodes, String separator) {
+    if (nodes != null) {
+      int size = nodes.length;
+      if (size > 0) {
+        _writer.print(prefix);
+        for (int i = 0; i < size; i++) {
+          if (i > 0) {
+            _writer.print(separator);
+          }
+          nodes[i].accept(this);
+        }
+      }
+    }
+  }
+
+  /**
+   * Print a list of [nodes], separated by the given [separator], followed by
+   * the given [suffix] if the list is not empty.
+   */
+  void _visitNodeListWithSeparatorAndSuffix(
+      NodeList<AstNode> nodes, String separator, String suffix) {
+    if (nodes != null) {
+      int size = nodes.length;
+      if (size > 0) {
+        for (int i = 0; i < size; i++) {
+          if (i > 0) {
+            _writer.print(separator);
+          }
+          nodes[i].accept(this);
+        }
+        _writer.print(suffix);
+      }
+    }
+  }
+
+  /**
+   * Safely visit the given [node], printing the [prefix] before the node if it
+   * is non-`null`.
+   */
+  void _visitNodeWithPrefix(String prefix, AstNode node) {
+    if (node != null) {
+      _writer.print(prefix);
+      node.accept(this);
+    }
+  }
+
+  /**
+   * Safely visit the given [node], printing the [suffix] after the node if it
+   * is non-`null`.
+   */
+  void _visitNodeWithSuffix(AstNode node, String suffix) {
+    if (node != null) {
+      node.accept(this);
+      _writer.print(suffix);
+    }
+  }
+
+  /**
+   * Safely visit the given [token], printing the [suffix] after the token if it
+   * is non-`null`.
+   */
+  void _visitTokenWithSuffix(Token token, String suffix) {
+    if (token != null) {
+      _writer.print(token.lexeme);
+      _writer.print(suffix);
+    }
+  }
+}
+
+/**
+ * A try statement.
+ *
+ * > tryStatement ::=
+ * >     'try' [Block] ([CatchClause]+ finallyClause? | finallyClause)
+ * >
+ * > finallyClause ::=
+ * >     'finally' [Block]
+ */
+class TryStatement extends Statement {
+  /**
+   * The token representing the 'try' keyword.
+   */
+  Token tryKeyword;
+
+  /**
+   * The body of the statement.
+   */
+  Block _body;
+
+  /**
+   * The catch clauses contained in the try statement.
+   */
+  NodeList<CatchClause> _catchClauses;
+
+  /**
+   * The token representing the 'finally' keyword, or `null` if the statement
+   * does not contain a finally clause.
+   */
+  Token finallyKeyword;
+
+  /**
+   * The finally block contained in the try statement, or `null` if the
+   * statement does not contain a finally clause.
+   */
+  Block _finallyBlock;
+
+  /**
+   * Initialize a newly created try statement. The list of [catchClauses] can be
+   * `null` if there are no catch clauses. The [finallyKeyword] and
+   * [finallyBlock] can be `null` if there is no finally clause.
+   */
+  TryStatement(this.tryKeyword, Block body, List<CatchClause> catchClauses,
+      this.finallyKeyword, Block finallyBlock) {
+    _body = _becomeParentOf(body);
+    _catchClauses = new NodeList<CatchClause>(this, catchClauses);
+    _finallyBlock = _becomeParentOf(finallyBlock);
+  }
+
+  @override
+  Token get beginToken => tryKeyword;
+
+  /**
+   * Return the body of the statement.
+   */
+  Block get body => _body;
+
+  /**
+   * Set the body of the statement to the given [block].
+   */
+  void set body(Block block) {
+    _body = _becomeParentOf(block);
+  }
+
+  /**
+   * Return the catch clauses contained in the try statement.
+   */
+  NodeList<CatchClause> get catchClauses => _catchClauses;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(tryKeyword)
+    ..add(_body)
+    ..addAll(_catchClauses)
+    ..add(finallyKeyword)
+    ..add(_finallyBlock);
+
+  @override
+  Token get endToken {
+    if (_finallyBlock != null) {
+      return _finallyBlock.endToken;
+    } else if (finallyKeyword != null) {
+      return finallyKeyword;
+    } else if (!_catchClauses.isEmpty) {
+      return _catchClauses.endToken;
+    }
+    return _body.endToken;
+  }
+
+  /**
+   * Return the finally block contained in the try statement, or `null` if the
+   * statement does not contain a finally clause.
+   */
+  Block get finallyBlock => _finallyBlock;
+
+  /**
+   * Set the finally block contained in the try statement to the given [block].
+   */
+  void set finallyBlock(Block block) {
+    _finallyBlock = _becomeParentOf(block);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitTryStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_body, visitor);
+    _catchClauses.accept(visitor);
+    _safelyVisitChild(_finallyBlock, visitor);
+  }
+}
+
+/**
+ * The declaration of a type alias.
+ *
+ * > typeAlias ::=
+ * >     'typedef' typeAliasBody
+ * >
+ * > typeAliasBody ::=
+ * >     classTypeAlias
+ * >   | functionTypeAlias
+ */
+abstract class TypeAlias extends NamedCompilationUnitMember {
+  /**
+   * The token representing the 'typedef' keyword.
+   */
+  Token typedefKeyword;
+
+  /**
+   * The semicolon terminating the declaration.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created type alias. Either or both of the [comment] and
+   * [metadata] can be `null` if the declaration does not have the corresponding
+   * attribute.
+   */
+  TypeAlias(Comment comment, List<Annotation> metadata, this.typedefKeyword,
+      SimpleIdentifier name, this.semicolon)
+      : super(comment, metadata, name);
+
+  @override
+  Token get endToken => semicolon;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata => typedefKeyword;
+
+  /**
+   * Return the token representing the 'typedef' keyword.
+   */
+  @deprecated // Use "this.typedefKeyword"
+  Token get keyword => typedefKeyword;
+
+  /**
+   * Set the token representing the 'typedef' keyword to the given [token].
+   */
+  @deprecated // Use "this.typedefKeyword"
+  set keyword(Token token) {
+    typedefKeyword = token;
+  }
+}
+
+/**
+ * A list of type arguments.
+ *
+ * > typeArguments ::=
+ * >     '<' typeName (',' typeName)* '>'
+ */
+class TypeArgumentList extends AstNode {
+  /**
+   * The left bracket.
+   */
+  Token leftBracket;
+
+  /**
+   * The type arguments associated with the type.
+   */
+  NodeList<TypeName> _arguments;
+
+  /**
+   * The right bracket.
+   */
+  Token rightBracket;
+
+  /**
+   * Initialize a newly created list of type arguments.
+   */
+  TypeArgumentList(
+      this.leftBracket, List<TypeName> arguments, this.rightBracket) {
+    _arguments = new NodeList<TypeName>(this, arguments);
+  }
+
+  /**
+   * Return the type arguments associated with the type.
+   */
+  NodeList<TypeName> get arguments => _arguments;
+
+  @override
+  Token get beginToken => leftBracket;
+
+  /**
+   * TODO(paulberry): Add commas.
+   */
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(leftBracket)
+    ..addAll(_arguments)
+    ..add(rightBracket);
+
+  @override
+  Token get endToken => rightBracket;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitTypeArgumentList(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _arguments.accept(visitor);
+  }
+}
+
+/**
+ * A literal that has a type associated with it.
+ *
+ * > typedLiteral ::=
+ * >     [ListLiteral]
+ * >   | [MapLiteral]
+ */
+abstract class TypedLiteral extends Literal {
+  /**
+   * The token representing the 'const' keyword, or `null` if the literal is not
+   * a constant.
+   */
+  Token constKeyword;
+
+  /**
+   * The type argument associated with this literal, or `null` if no type
+   * arguments were declared.
+   */
+  TypeArgumentList _typeArguments;
+
+  /**
+   * Initialize a newly created typed literal. The [constKeyword] can be `null`\
+   * if the literal is not a constant. The [typeArguments] can be `null` if no
+   * type arguments were declared.
+   */
+  TypedLiteral(this.constKeyword, TypeArgumentList typeArguments) {
+    _typeArguments = _becomeParentOf(typeArguments);
+  }
+
+  /**
+   * Return the type argument associated with this literal, or `null` if no type
+   * arguments were declared.
+   */
+  TypeArgumentList get typeArguments => _typeArguments;
+
+  /**
+   * Set the type argument associated with this literal to the given
+   * [typeArguments].
+   */
+  void set typeArguments(TypeArgumentList typeArguments) {
+    _typeArguments = _becomeParentOf(typeArguments);
+  }
+
+  ChildEntities get _childEntities =>
+      new ChildEntities()..add(constKeyword)..add(_typeArguments);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_typeArguments, visitor);
+  }
+}
+
+/**
+ * The name of a type, which can optionally include type arguments.
+ *
+ * > typeName ::=
+ * >     [Identifier] typeArguments?
+ */
+class TypeName extends AstNode {
+  /**
+   * The name of the type.
+   */
+  Identifier _name;
+
+  /**
+   * The type arguments associated with the type, or `null` if there are no type
+   * arguments.
+   */
+  TypeArgumentList _typeArguments;
+
+  /**
+   * The type being named, or `null` if the AST structure has not been resolved.
+   */
+  DartType type;
+
+  /**
+   * Initialize a newly created type name. The [typeArguments] can be `null` if
+   * there are no type arguments.
+   */
+  TypeName(Identifier name, TypeArgumentList typeArguments) {
+    _name = _becomeParentOf(name);
+    _typeArguments = _becomeParentOf(typeArguments);
+  }
+
+  @override
+  Token get beginToken => _name.beginToken;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_name)..add(_typeArguments);
+
+  @override
+  Token get endToken {
+    if (_typeArguments != null) {
+      return _typeArguments.endToken;
+    }
+    return _name.endToken;
+  }
+
+  /**
+   * Return `true` if this type is a deferred type.
+   *
+   * 15.1 Static Types: A type <i>T</i> is deferred iff it is of the form
+   * </i>p.T</i> where <i>p</i> is a deferred prefix.
+   */
+  bool get isDeferred {
+    Identifier identifier = name;
+    if (identifier is! PrefixedIdentifier) {
+      return false;
+    }
+    return (identifier as PrefixedIdentifier).isDeferred;
+  }
+
+  @override
+  bool get isSynthetic => _name.isSynthetic && _typeArguments == null;
+
+  /**
+   * Return the name of the type.
+   */
+  Identifier get name => _name;
+
+  /**
+   * Set the name of the type to the given [identifier].
+   */
+  void set name(Identifier identifier) {
+    _name = _becomeParentOf(identifier);
+  }
+
+  /**
+   * Return the type arguments associated with the type, or `null` if there are
+   * no type arguments.
+   */
+  TypeArgumentList get typeArguments => _typeArguments;
+
+  /**
+   * Set the type arguments associated with the type to the given
+   * [typeArguments].
+   */
+  void set typeArguments(TypeArgumentList typeArguments) {
+    _typeArguments = _becomeParentOf(typeArguments);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitTypeName(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_typeArguments, visitor);
+  }
+}
+
+/**
+ * A type parameter.
+ *
+ * > typeParameter ::=
+ * >     [SimpleIdentifier] ('extends' [TypeName])?
+ */
+class TypeParameter extends Declaration {
+  /**
+   * The name of the type parameter.
+   */
+  SimpleIdentifier _name;
+
+  /**
+   * The token representing the 'extends' keyword, or `null` if there is no
+   * explicit upper bound.
+   */
+  Token extendsKeyword;
+
+  /**
+   * The name of the upper bound for legal arguments, or `null` if there is no
+   * explicit upper bound.
+   */
+  TypeName _bound;
+
+  /**
+   * Initialize a newly created type parameter. Either or both of the [comment]
+   * and [metadata] can be `null` if the parameter does not have the
+   * corresponding attribute. The [extendsKeyword] and [bound] can be `null` if
+   * the parameter does not have an upper bound.
+   */
+  TypeParameter(Comment comment, List<Annotation> metadata,
+      SimpleIdentifier name, this.extendsKeyword, TypeName bound)
+      : super(comment, metadata) {
+    _name = _becomeParentOf(name);
+    _bound = _becomeParentOf(bound);
+  }
+
+  /**
+   * Return the name of the upper bound for legal arguments, or `null` if there
+   * is no explicit upper bound.
+   */
+  TypeName get bound => _bound;
+
+  /**
+   * Set the name of the upper bound for legal arguments to the given
+   * [typeName].
+   */
+  void set bound(TypeName typeName) {
+    _bound = _becomeParentOf(typeName);
+  }
+
+  @override
+  Iterable get childEntities =>
+      super._childEntities..add(_name)..add(extendsKeyword)..add(_bound);
+
+  @override
+  TypeParameterElement get element =>
+      _name != null ? (_name.staticElement as TypeParameterElement) : null;
+
+  @override
+  Token get endToken {
+    if (_bound == null) {
+      return _name.endToken;
+    }
+    return _bound.endToken;
+  }
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata => _name.beginToken;
+
+  /**
+   * Return the token representing the 'extends' keyword, or `null` if there is
+   * no explicit upper bound.
+   */
+  @deprecated // Use "this.extendsKeyword"
+  Token get keyword => extendsKeyword;
+
+  /**
+   * Set the token representing the 'extends' keyword to the given [token].
+   */
+  @deprecated // Use "this.extendsKeyword"
+  set keyword(Token token) {
+    extendsKeyword = token;
+  }
+
+  /**
+   * Return the name of the type parameter.
+   */
+  SimpleIdentifier get name => _name;
+
+  /**
+   * Set the name of the type parameter to the given [identifier].
+   */
+  void set name(SimpleIdentifier identifier) {
+    _name = _becomeParentOf(identifier);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitTypeParameter(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_bound, visitor);
+  }
+}
+
+/**
+ * Type parameters within a declaration.
+ *
+ * > typeParameterList ::=
+ * >     '<' [TypeParameter] (',' [TypeParameter])* '>'
+ */
+class TypeParameterList extends AstNode {
+  /**
+   * The left angle bracket.
+   */
+  final Token leftBracket;
+
+  /**
+   * The type parameters in the list.
+   */
+  NodeList<TypeParameter> _typeParameters;
+
+  /**
+   * The right angle bracket.
+   */
+  final Token rightBracket;
+
+  /**
+   * Initialize a newly created list of type parameters.
+   */
+  TypeParameterList(
+      this.leftBracket, List<TypeParameter> typeParameters, this.rightBracket) {
+    _typeParameters = new NodeList<TypeParameter>(this, typeParameters);
+  }
+
+  @override
+  Token get beginToken => leftBracket;
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(leftBracket)
+    ..addAll(_typeParameters)
+    ..add(rightBracket);
+
+  @override
+  Token get endToken => rightBracket;
+
+  /**
+   * Return the type parameters for the type.
+   */
+  NodeList<TypeParameter> get typeParameters => _typeParameters;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitTypeParameterList(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _typeParameters.accept(visitor);
+  }
+}
+
+/**
+ * An AST visitor that will recursively visit all of the nodes in an AST
+ * structure (like instances of the class [RecursiveAstVisitor]). In addition,
+ * every node will also be visited by using a single unified [visitNode] method.
+ *
+ * Subclasses that override a visit method must either invoke the overridden
+ * visit method or explicitly invoke the more general [visitNode] method.
+ * Failure to do so will cause the children of the visited node to not be
+ * visited.
+ */
+class UnifyingAstVisitor<R> implements AstVisitor<R> {
+  @override
+  R visitAdjacentStrings(AdjacentStrings node) => visitNode(node);
+
+  @override
+  R visitAnnotation(Annotation node) => visitNode(node);
+
+  @override
+  R visitArgumentList(ArgumentList node) => visitNode(node);
+
+  @override
+  R visitAsExpression(AsExpression node) => visitNode(node);
+
+  @override
+  R visitAssertStatement(AssertStatement node) => visitNode(node);
+
+  @override
+  R visitAssignmentExpression(AssignmentExpression node) => visitNode(node);
+
+  @override
+  R visitAwaitExpression(AwaitExpression node) => visitNode(node);
+
+  @override
+  R visitBinaryExpression(BinaryExpression node) => visitNode(node);
+
+  @override
+  R visitBlock(Block node) => visitNode(node);
+
+  @override
+  R visitBlockFunctionBody(BlockFunctionBody node) => visitNode(node);
+
+  @override
+  R visitBooleanLiteral(BooleanLiteral node) => visitNode(node);
+
+  @override
+  R visitBreakStatement(BreakStatement node) => visitNode(node);
+
+  @override
+  R visitCascadeExpression(CascadeExpression node) => visitNode(node);
+
+  @override
+  R visitCatchClause(CatchClause node) => visitNode(node);
+
+  @override
+  R visitClassDeclaration(ClassDeclaration node) => visitNode(node);
+
+  @override
+  R visitClassTypeAlias(ClassTypeAlias node) => visitNode(node);
+
+  @override
+  R visitComment(Comment node) => visitNode(node);
+
+  @override
+  R visitCommentReference(CommentReference node) => visitNode(node);
+
+  @override
+  R visitCompilationUnit(CompilationUnit node) => visitNode(node);
+
+  @override
+  R visitConditionalExpression(ConditionalExpression node) => visitNode(node);
+
+  @override
+  R visitConstructorDeclaration(ConstructorDeclaration node) => visitNode(node);
+
+  @override
+  R visitConstructorFieldInitializer(ConstructorFieldInitializer node) =>
+      visitNode(node);
+
+  @override
+  R visitConstructorName(ConstructorName node) => visitNode(node);
+
+  @override
+  R visitContinueStatement(ContinueStatement node) => visitNode(node);
+
+  @override
+  R visitDeclaredIdentifier(DeclaredIdentifier node) => visitNode(node);
+
+  @override
+  R visitDefaultFormalParameter(DefaultFormalParameter node) => visitNode(node);
+
+  @override
+  R visitDoStatement(DoStatement node) => visitNode(node);
+
+  @override
+  R visitDoubleLiteral(DoubleLiteral node) => visitNode(node);
+
+  @override
+  R visitEmptyFunctionBody(EmptyFunctionBody node) => visitNode(node);
+
+  @override
+  R visitEmptyStatement(EmptyStatement node) => visitNode(node);
+
+  @override
+  R visitEnumConstantDeclaration(EnumConstantDeclaration node) =>
+      visitNode(node);
+
+  @override
+  R visitEnumDeclaration(EnumDeclaration node) => visitNode(node);
+
+  @override
+  R visitExportDirective(ExportDirective node) => visitNode(node);
+
+  @override
+  R visitExpressionFunctionBody(ExpressionFunctionBody node) => visitNode(node);
+
+  @override
+  R visitExpressionStatement(ExpressionStatement node) => visitNode(node);
+
+  @override
+  R visitExtendsClause(ExtendsClause node) => visitNode(node);
+
+  @override
+  R visitFieldDeclaration(FieldDeclaration node) => visitNode(node);
+
+  @override
+  R visitFieldFormalParameter(FieldFormalParameter node) => visitNode(node);
+
+  @override
+  R visitForEachStatement(ForEachStatement node) => visitNode(node);
+
+  @override
+  R visitFormalParameterList(FormalParameterList node) => visitNode(node);
+
+  @override
+  R visitForStatement(ForStatement node) => visitNode(node);
+
+  @override
+  R visitFunctionDeclaration(FunctionDeclaration node) => visitNode(node);
+
+  @override
+  R visitFunctionDeclarationStatement(FunctionDeclarationStatement node) =>
+      visitNode(node);
+
+  @override
+  R visitFunctionExpression(FunctionExpression node) => visitNode(node);
+
+  @override
+  R visitFunctionExpressionInvocation(FunctionExpressionInvocation node) =>
+      visitNode(node);
+
+  @override
+  R visitFunctionTypeAlias(FunctionTypeAlias node) => visitNode(node);
+
+  @override
+  R visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) =>
+      visitNode(node);
+
+  @override
+  R visitHideCombinator(HideCombinator node) => visitNode(node);
+
+  @override
+  R visitIfStatement(IfStatement node) => visitNode(node);
+
+  @override
+  R visitImplementsClause(ImplementsClause node) => visitNode(node);
+
+  @override
+  R visitImportDirective(ImportDirective node) => visitNode(node);
+
+  @override
+  R visitIndexExpression(IndexExpression node) => visitNode(node);
+
+  @override
+  R visitInstanceCreationExpression(InstanceCreationExpression node) =>
+      visitNode(node);
+
+  @override
+  R visitIntegerLiteral(IntegerLiteral node) => visitNode(node);
+
+  @override
+  R visitInterpolationExpression(InterpolationExpression node) =>
+      visitNode(node);
+
+  @override
+  R visitInterpolationString(InterpolationString node) => visitNode(node);
+
+  @override
+  R visitIsExpression(IsExpression node) => visitNode(node);
+
+  @override
+  R visitLabel(Label node) => visitNode(node);
+
+  @override
+  R visitLabeledStatement(LabeledStatement node) => visitNode(node);
+
+  @override
+  R visitLibraryDirective(LibraryDirective node) => visitNode(node);
+
+  @override
+  R visitLibraryIdentifier(LibraryIdentifier node) => visitNode(node);
+
+  @override
+  R visitListLiteral(ListLiteral node) => visitNode(node);
+
+  @override
+  R visitMapLiteral(MapLiteral node) => visitNode(node);
+
+  @override
+  R visitMapLiteralEntry(MapLiteralEntry node) => visitNode(node);
+
+  @override
+  R visitMethodDeclaration(MethodDeclaration node) => visitNode(node);
+
+  @override
+  R visitMethodInvocation(MethodInvocation node) => visitNode(node);
+
+  @override
+  R visitNamedExpression(NamedExpression node) => visitNode(node);
+
+  @override
+  R visitNativeClause(NativeClause node) => visitNode(node);
+
+  @override
+  R visitNativeFunctionBody(NativeFunctionBody node) => visitNode(node);
+
+  R visitNode(AstNode node) {
+    node.visitChildren(this);
+    return null;
+  }
+
+  @override
+  R visitNullLiteral(NullLiteral node) => visitNode(node);
+
+  @override
+  R visitParenthesizedExpression(ParenthesizedExpression node) =>
+      visitNode(node);
+
+  @override
+  R visitPartDirective(PartDirective node) => visitNode(node);
+
+  @override
+  R visitPartOfDirective(PartOfDirective node) => visitNode(node);
+
+  @override
+  R visitPostfixExpression(PostfixExpression node) => visitNode(node);
+
+  @override
+  R visitPrefixedIdentifier(PrefixedIdentifier node) => visitNode(node);
+
+  @override
+  R visitPrefixExpression(PrefixExpression node) => visitNode(node);
+
+  @override
+  R visitPropertyAccess(PropertyAccess node) => visitNode(node);
+
+  @override
+  R visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) => visitNode(node);
+
+  @override
+  R visitRethrowExpression(RethrowExpression node) => visitNode(node);
+
+  @override
+  R visitReturnStatement(ReturnStatement node) => visitNode(node);
+
+  @override
+  R visitScriptTag(ScriptTag scriptTag) => visitNode(scriptTag);
+
+  @override
+  R visitShowCombinator(ShowCombinator node) => visitNode(node);
+
+  @override
+  R visitSimpleFormalParameter(SimpleFormalParameter node) => visitNode(node);
+
+  @override
+  R visitSimpleIdentifier(SimpleIdentifier node) => visitNode(node);
+
+  @override
+  R visitSimpleStringLiteral(SimpleStringLiteral node) => visitNode(node);
+
+  @override
+  R visitStringInterpolation(StringInterpolation node) => visitNode(node);
+
+  @override
+  R visitSuperConstructorInvocation(SuperConstructorInvocation node) =>
+      visitNode(node);
+
+  @override
+  R visitSuperExpression(SuperExpression node) => visitNode(node);
+
+  @override
+  R visitSwitchCase(SwitchCase node) => visitNode(node);
+
+  @override
+  R visitSwitchDefault(SwitchDefault node) => visitNode(node);
+
+  @override
+  R visitSwitchStatement(SwitchStatement node) => visitNode(node);
+
+  @override
+  R visitSymbolLiteral(SymbolLiteral node) => visitNode(node);
+
+  @override
+  R visitThisExpression(ThisExpression node) => visitNode(node);
+
+  @override
+  R visitThrowExpression(ThrowExpression node) => visitNode(node);
+
+  @override
+  R visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) =>
+      visitNode(node);
+
+  @override
+  R visitTryStatement(TryStatement node) => visitNode(node);
+
+  @override
+  R visitTypeArgumentList(TypeArgumentList node) => visitNode(node);
+
+  @override
+  R visitTypeName(TypeName node) => visitNode(node);
+
+  @override
+  R visitTypeParameter(TypeParameter node) => visitNode(node);
+
+  @override
+  R visitTypeParameterList(TypeParameterList node) => visitNode(node);
+
+  @override
+  R visitVariableDeclaration(VariableDeclaration node) => visitNode(node);
+
+  @override
+  R visitVariableDeclarationList(VariableDeclarationList node) =>
+      visitNode(node);
+
+  @override
+  R visitVariableDeclarationStatement(VariableDeclarationStatement node) =>
+      visitNode(node);
+
+  @override
+  R visitWhileStatement(WhileStatement node) => visitNode(node);
+
+  @override
+  R visitWithClause(WithClause node) => visitNode(node);
+
+  @override
+  R visitYieldStatement(YieldStatement node) => visitNode(node);
+}
+
+/**
+ * A directive that references a URI.
+ *
+ * > uriBasedDirective ::=
+ * >     [ExportDirective]
+ * >   | [ImportDirective]
+ * >   | [PartDirective]
+ */
+abstract class UriBasedDirective extends Directive {
+  /**
+   * The prefix of a URI using the `dart-ext` scheme to reference a native code
+   * library.
+   */
+  static String _DART_EXT_SCHEME = "dart-ext:";
+
+  /**
+   * The URI referenced by this directive.
+   */
+  StringLiteral _uri;
+
+  /**
+   * The content of the URI.
+   */
+  String uriContent;
+
+  /**
+   * The source to which the URI was resolved.
+   */
+  Source source;
+
+  /**
+   * Initialize a newly create URI-based directive. Either or both of the
+   * [comment] and [metadata] can be `null` if the directive does not have the
+   * corresponding attribute.
+   */
+  UriBasedDirective(
+      Comment comment, List<Annotation> metadata, StringLiteral uri)
+      : super(comment, metadata) {
+    _uri = _becomeParentOf(uri);
+  }
+
+  /**
+   * Return the URI referenced by this directive.
+   */
+  StringLiteral get uri => _uri;
+
+  /**
+   * Set the URI referenced by this directive to the given [uri].
+   */
+  void set uri(StringLiteral uri) {
+    _uri = _becomeParentOf(uri);
+  }
+
+  /**
+   * Return the element associated with the URI of this directive, or `null` if
+   * the AST structure has not been resolved or if the URI could not be
+   * resolved. Examples of the latter case include a directive that contains an
+   * invalid URL or a URL that does not exist.
+   */
+  Element get uriElement;
+
+  /**
+   * Validate this directive, but do not check for existence. Return a code
+   * indicating the problem if there is one, or `null` no problem
+   */
+  UriValidationCode validate() {
+    StringLiteral uriLiteral = uri;
+    if (uriLiteral is StringInterpolation) {
+      return UriValidationCode.URI_WITH_INTERPOLATION;
+    }
+    String uriContent = this.uriContent;
+    if (uriContent == null) {
+      return UriValidationCode.INVALID_URI;
+    }
+    if (this is ImportDirective && uriContent.startsWith(_DART_EXT_SCHEME)) {
+      return UriValidationCode.URI_WITH_DART_EXT_SCHEME;
+    }
+    try {
+      parseUriWithException(Uri.encodeFull(uriContent));
+    } on URISyntaxException {
+      return UriValidationCode.INVALID_URI;
+    }
+    return null;
+  }
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_uri, visitor);
+  }
+}
+
+/**
+ * Validation codes returned by [UriBasedDirective.validate].
+ */
+class UriValidationCode {
+  static const UriValidationCode INVALID_URI =
+      const UriValidationCode('INVALID_URI');
+
+  static const UriValidationCode URI_WITH_INTERPOLATION =
+      const UriValidationCode('URI_WITH_INTERPOLATION');
+
+  static const UriValidationCode URI_WITH_DART_EXT_SCHEME =
+      const UriValidationCode('URI_WITH_DART_EXT_SCHEME');
+
+  /**
+   * The name of the validation code.
+   */
+  final String name;
+
+  /**
+   * Initialize a newly created validation code to have the given [name].
+   */
+  const UriValidationCode(this.name);
+
+  @override
+  String toString() => name;
+}
+
+/**
+ * An identifier that has an initial value associated with it. Instances of this
+ * class are always children of the class [VariableDeclarationList].
+ *
+ * > variableDeclaration ::=
+ * >     [SimpleIdentifier] ('=' [Expression])?
+ *
+ * TODO(paulberry): the grammar does not allow metadata to be associated with
+ * a VariableDeclaration, and currently we don't record comments for it either.
+ * Consider changing the class hierarchy so that [VariableDeclaration] does not
+ * extend [Declaration].
+ */
+class VariableDeclaration extends Declaration {
+  /**
+   * The name of the variable being declared.
+   */
+  SimpleIdentifier _name;
+
+  /**
+   * The equal sign separating the variable name from the initial value, or
+   * `null` if the initial value was not specified.
+   */
+  Token equals;
+
+  /**
+   * The expression used to compute the initial value for the variable, or
+   * `null` if the initial value was not specified.
+   */
+  Expression _initializer;
+
+  /**
+   * Initialize a newly created variable declaration. The [equals] and
+   * [initializer] can be `null` if there is no initializer.
+   */
+  VariableDeclaration(
+      SimpleIdentifier name, this.equals, Expression initializer)
+      : super(null, null) {
+    _name = _becomeParentOf(name);
+    _initializer = _becomeParentOf(initializer);
+  }
+
+  @override
+  Iterable get childEntities =>
+      super._childEntities..add(_name)..add(equals)..add(_initializer);
+
+  /**
+   * This overridden implementation of getDocumentationComment() looks in the
+   * grandparent node for dartdoc comments if no documentation is specifically
+   * available on the node.
+   */
+  @override
+  Comment get documentationComment {
+    Comment comment = super.documentationComment;
+    if (comment == null) {
+      if (parent != null && parent.parent != null) {
+        AstNode node = parent.parent;
+        if (node is AnnotatedNode) {
+          return node.documentationComment;
+        }
+      }
+    }
+    return comment;
+  }
+
+  @override
+  VariableElement get element =>
+      _name != null ? (_name.staticElement as VariableElement) : null;
+
+  @override
+  Token get endToken {
+    if (_initializer != null) {
+      return _initializer.endToken;
+    }
+    return _name.endToken;
+  }
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata => _name.beginToken;
+
+  /**
+   * Return the expression used to compute the initial value for the variable,
+   * or `null` if the initial value was not specified.
+   */
+  Expression get initializer => _initializer;
+
+  /**
+   * Set the expression used to compute the initial value for the variable to
+   * the given [expression].
+   */
+  void set initializer(Expression expression) {
+    _initializer = _becomeParentOf(expression);
+  }
+
+  /**
+   * Return `true` if this variable was declared with the 'const' modifier.
+   */
+  bool get isConst {
+    AstNode parent = this.parent;
+    return parent is VariableDeclarationList && parent.isConst;
+  }
+
+  /**
+   * Return `true` if this variable was declared with the 'final' modifier.
+   * Variables that are declared with the 'const' modifier will return `false`
+   * even though they are implicitly final.
+   */
+  bool get isFinal {
+    AstNode parent = this.parent;
+    return parent is VariableDeclarationList && parent.isFinal;
+  }
+
+  /**
+   * Return the name of the variable being declared.
+   */
+  SimpleIdentifier get name => _name;
+
+  /**
+   * Set the name of the variable being declared to the given [identifier].
+   */
+  void set name(SimpleIdentifier identifier) {
+    _name = _becomeParentOf(identifier);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitVariableDeclaration(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_name, visitor);
+    _safelyVisitChild(_initializer, visitor);
+  }
+}
+
+/**
+ * The declaration of one or more variables of the same type.
+ *
+ * > variableDeclarationList ::=
+ * >     finalConstVarOrType [VariableDeclaration] (',' [VariableDeclaration])*
+ * >
+ * > finalConstVarOrType ::=
+ * >   | 'final' [TypeName]?
+ * >   | 'const' [TypeName]?
+ * >   | 'var'
+ * >   | [TypeName]
+ */
+class VariableDeclarationList extends AnnotatedNode {
+  /**
+   * The token representing the 'final', 'const' or 'var' keyword, or `null` if
+   * no keyword was included.
+   */
+  Token keyword;
+
+  /**
+   * The type of the variables being declared, or `null` if no type was provided.
+   */
+  TypeName _type;
+
+  /**
+   * A list containing the individual variables being declared.
+   */
+  NodeList<VariableDeclaration> _variables;
+
+  /**
+   * Initialize a newly created variable declaration list. Either or both of the
+   * [comment] and [metadata] can be `null` if the variable list does not have
+   * the corresponding attribute. The [keyword] can be `null` if a type was
+   * specified. The [type] must be `null` if the keyword is 'var'.
+   */
+  VariableDeclarationList(Comment comment, List<Annotation> metadata,
+      this.keyword, TypeName type, List<VariableDeclaration> variables)
+      : super(comment, metadata) {
+    _type = _becomeParentOf(type);
+    _variables = new NodeList<VariableDeclaration>(this, variables);
+  }
+
+  /**
+   * TODO(paulberry): include commas.
+   */
+  @override
+  Iterable get childEntities => super._childEntities
+    ..add(keyword)
+    ..add(_type)
+    ..addAll(_variables);
+
+  @override
+  Token get endToken => _variables.endToken;
+
+  @override
+  Token get firstTokenAfterCommentAndMetadata {
+    if (keyword != null) {
+      return keyword;
+    } else if (_type != null) {
+      return _type.beginToken;
+    }
+    return _variables.beginToken;
+  }
+
+  /**
+   * Return `true` if the variables in this list were declared with the 'const'
+   * modifier.
+   */
+  bool get isConst => keyword is KeywordToken &&
+      (keyword as KeywordToken).keyword == Keyword.CONST;
+
+  /**
+   * Return `true` if the variables in this list were declared with the 'final'
+   * modifier. Variables that are declared with the 'const' modifier will return
+   * `false` even though they are implicitly final. (In other words, this is a
+   * syntactic check rather than a semantic check.)
+   */
+  bool get isFinal => keyword is KeywordToken &&
+      (keyword as KeywordToken).keyword == Keyword.FINAL;
+
+  /**
+   * Return the type of the variables being declared, or `null` if no type was
+   * provided.
+   */
+  TypeName get type => _type;
+
+  /**
+   * Set the type of the variables being declared to the given [typeName].
+   */
+  void set type(TypeName typeName) {
+    _type = _becomeParentOf(typeName);
+  }
+
+  /**
+   * Return a list containing the individual variables being declared.
+   */
+  NodeList<VariableDeclaration> get variables => _variables;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitVariableDeclarationList(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    super.visitChildren(visitor);
+    _safelyVisitChild(_type, visitor);
+    _variables.accept(visitor);
+  }
+}
+
+/**
+ * A list of variables that are being declared in a context where a statement is
+ * required.
+ *
+ * > variableDeclarationStatement ::=
+ * >     [VariableDeclarationList] ';'
+ */
+class VariableDeclarationStatement extends Statement {
+  /**
+   * The variables being declared.
+   */
+  VariableDeclarationList _variableList;
+
+  /**
+   * The semicolon terminating the statement.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created variable declaration statement.
+   */
+  VariableDeclarationStatement(
+      VariableDeclarationList variableList, this.semicolon) {
+    _variableList = _becomeParentOf(variableList);
+  }
+
+  @override
+  Token get beginToken => _variableList.beginToken;
+
+  @override
+  Iterable get childEntities =>
+      new ChildEntities()..add(_variableList)..add(semicolon);
+
+  @override
+  Token get endToken => semicolon;
+
+  /**
+   * Return the variables being declared.
+   */
+  VariableDeclarationList get variables => _variableList;
+
+  /**
+   * Set the variables being declared to the given list of [variables].
+   */
+  void set variables(VariableDeclarationList variables) {
+    _variableList = _becomeParentOf(variables);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitVariableDeclarationStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_variableList, visitor);
+  }
+}
+
+/**
+ * A while statement.
+ *
+ * > whileStatement ::=
+ * >     'while' '(' [Expression] ')' [Statement]
+ */
+class WhileStatement extends Statement {
+  /**
+   * The token representing the 'while' keyword.
+   */
+  Token whileKeyword;
+
+  /**
+   * The left parenthesis.
+   */
+  Token leftParenthesis;
+
+  /**
+   * The expression used to determine whether to execute the body of the loop.
+   */
+  Expression _condition;
+
+  /**
+   * The right parenthesis.
+   */
+  Token rightParenthesis;
+
+  /**
+   * The body of the loop.
+   */
+  Statement _body;
+
+  /**
+   * Initialize a newly created while statement.
+   */
+  WhileStatement(this.whileKeyword, this.leftParenthesis, Expression condition,
+      this.rightParenthesis, Statement body) {
+    _condition = _becomeParentOf(condition);
+    _body = _becomeParentOf(body);
+  }
+
+  @override
+  Token get beginToken => whileKeyword;
+
+  /**
+   * Return the body of the loop.
+   */
+  Statement get body => _body;
+
+  /**
+   * Set the body of the loop to the given [statement].
+   */
+  void set body(Statement statement) {
+    _body = _becomeParentOf(statement);
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(whileKeyword)
+    ..add(leftParenthesis)
+    ..add(_condition)
+    ..add(rightParenthesis)
+    ..add(_body);
+
+  /**
+   * Return the expression used to determine whether to execute the body of the
+   * loop.
+   */
+  Expression get condition => _condition;
+
+  /**
+   * Set the expression used to determine whether to execute the body of the
+   * loop to the given [expression].
+   */
+  void set condition(Expression expression) {
+    _condition = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get endToken => _body.endToken;
+
+  /**
+   * Return the token representing the 'while' keyword.
+   */
+  @deprecated // Use "this.whileKeyword"
+  Token get keyword => whileKeyword;
+
+  /**
+   * Set the token representing the 'while' keyword to the given [token].
+   */
+  @deprecated // Use "this.whileKeyword"
+  set keyword(Token token) {
+    whileKeyword = token;
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitWhileStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_condition, visitor);
+    _safelyVisitChild(_body, visitor);
+  }
+}
+
+/**
+ * The with clause in a class declaration.
+ *
+ * > withClause ::=
+ * >     'with' [TypeName] (',' [TypeName])*
+ */
+class WithClause extends AstNode {
+  /**
+   * The token representing the 'with' keyword.
+   */
+  Token withKeyword;
+
+  /**
+   * The names of the mixins that were specified.
+   */
+  NodeList<TypeName> _mixinTypes;
+
+  /**
+   * Initialize a newly created with clause.
+   */
+  WithClause(this.withKeyword, List<TypeName> mixinTypes) {
+    _mixinTypes = new NodeList<TypeName>(this, mixinTypes);
+  }
+
+  @override
+  Token get beginToken => withKeyword;
+
+  /**
+   * TODO(paulberry): add commas.
+   */
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(withKeyword)
+    ..addAll(_mixinTypes);
+
+  @override
+  Token get endToken => _mixinTypes.endToken;
+
+  /**
+   * Set the token representing the 'with' keyword to the given [token].
+   */
+  @deprecated // Use "this.withKeyword"
+  void set mixinKeyword(Token token) {
+    this.withKeyword = token;
+  }
+
+  /**
+   * Return the names of the mixins that were specified.
+   */
+  NodeList<TypeName> get mixinTypes => _mixinTypes;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitWithClause(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _mixinTypes.accept(visitor);
+  }
+}
+
+/**
+ * A yield statement.
+ *
+ * > yieldStatement ::=
+ * >     'yield' '*'? [Expression] ‘;’
+ */
+class YieldStatement extends Statement {
+  /**
+   * The 'yield' keyword.
+   */
+  Token yieldKeyword;
+
+  /**
+   * The star optionally following the 'yield' keyword.
+   */
+  Token star;
+
+  /**
+   * The expression whose value will be yielded.
+   */
+  Expression _expression;
+
+  /**
+   * The semicolon following the expression.
+   */
+  Token semicolon;
+
+  /**
+   * Initialize a newly created yield expression. The [star] can be `null` if no
+   * star was provided.
+   */
+  YieldStatement(
+      this.yieldKeyword, this.star, Expression expression, this.semicolon) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  Token get beginToken {
+    if (yieldKeyword != null) {
+      return yieldKeyword;
+    }
+    return _expression.beginToken;
+  }
+
+  @override
+  Iterable get childEntities => new ChildEntities()
+    ..add(yieldKeyword)
+    ..add(star)
+    ..add(_expression)
+    ..add(semicolon);
+
+  @override
+  Token get endToken {
+    if (semicolon != null) {
+      return semicolon;
+    }
+    return _expression.endToken;
+  }
+
+  /**
+   * Return the expression whose value will be yielded.
+   */
+  Expression get expression => _expression;
+
+  /**
+   * Set the expression whose value will be yielded to the given [expression].
+   */
+  void set expression(Expression expression) {
+    _expression = _becomeParentOf(expression);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitYieldStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+  }
+}