First step towards a public API for AST nodes

pkg/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 analyzer.src.generated.ast;
 
 import 'dart:collection';
 
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/src/dart/ast/utilities.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/generated/engine.dart' show AnalysisEngine;
 import 'package:analyzer/src/generated/java_core.dart';
 import 'package:analyzer/src/generated/java_engine.dart';
 import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:analyzer/src/generated/source.dart' show LineInfo, Source;
-import 'package:analyzer/src/generated/utilities_collection.dart' show TokenMap;
 import 'package:analyzer/src/generated/utilities_dart.dart';
 
+export 'package:analyzer/dart/ast/visitor.dart';
+export 'package:analyzer/src/dart/ast/utilities.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]+
@@ skipping 867 matching lines @@
   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.comma),
-      cloneNode(node.message),
-      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
-  Configuration visitConfiguration(Configuration node) => new Configuration(
-      cloneToken(node.ifKeyword),
-      cloneToken(node.leftParenthesis),
-      cloneNode(node.name),
-      cloneToken(node.equalToken),
-      cloneNode(node.value),
-      cloneToken(node.rightParenthesis),
-      cloneNode(node.libraryUri));
-
-  @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
-  DottedName visitDottedName(DottedName node) =>
-      new DottedName(cloneNodeList(node.components));
-
-  @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.configurations),
-        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),
-        cloneNodeList(node.configurations),
-        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.comma, other.comma) &&
-        isEqualNodes(node.message, other.message) &&
-        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 visitConfiguration(Configuration node) {
-    Configuration other = _other as Configuration;
-    return isEqualTokens(node.ifKeyword, other.ifKeyword) &&
-        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
-        isEqualNodes(node.name, other.name) &&
-        isEqualTokens(node.equalToken, other.equalToken) &&
-        isEqualNodes(node.value, other.value) &&
-        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
-        isEqualNodes(node.libraryUri, other.libraryUri);
-  }
-
-  @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 visitDottedName(DottedName node) {
-    DottedName other = _other as DottedName;
-    return _isEqualNodeLists(node.components, other.components);
-  }
-
-  @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.
    */
   static const List<AstNode> EMPTY_LIST = const <AstNode>[];
 
   /**
    * A comparator that can be used to sort AST nodes in lexical order. In other
@@ skipping 790 matching lines @@
   @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;
@@ skipping 1383 matching lines @@
   accept(AstVisitor visitor) => visitor.visitConfiguration(this);
 
   @override
   void visitChildren(AstVisitor visitor) {
     _safelyVisitChild(_name, visitor);
     _safelyVisitChild(_value, visitor);
     _safelyVisitChild(_libraryUri, visitor);
   }
 }
 
-/// Instances of the class [ConstantEvaluator] evaluate constant expressions to
-/// produce their compile-time value.
-///
-/// According to the Dart Language Specification:
-///
-/// > 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**.
-/// > * A literal symbol.
-/// > * **null**.
-/// > * A qualified reference to a static constant variable.
-/// > * An identifier expression that denotes a constant variable, class or type
-/// >   alias.
-/// > * 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.
-/// > * <span>
-/// >   An expression of the form <i>identical(e<sub>1</sub>, e<sub>2</sub>)</i>
-/// >   where <i>e<sub>1</sub></i> and <i>e<sub>2</sub></i> are constant
-/// >   expressions and <i>identical()</i> is statically bound to the predefined
-/// >   dart function <i>identical()</i> discussed above.
-/// >   </span>
-/// > * <span>
-/// >   An expression of one of the forms <i>e<sub>1</sub> == e<sub>2</sub></i>
-/// >   or <i>e<sub>1</sub> != e<sub>2</sub></i> where <i>e<sub>1</sub></i> and
-/// >   <i>e<sub>2</sub></i> are constant expressions that evaluate to a
-/// >   numeric, string or boolean value.
-/// >   </span>
-/// > * <span>
-/// >   An expression of one of the forms <i>!e</i>, <i>e<sub>1</sub> &amp;&amp;
-/// >   e<sub>2</sub></i> or <i>e<sub>1</sub> || e<sub>2</sub></i>, where
-/// >   <i>e</i>, <i>e<sub>1</sub></i> and <i>e<sub>2</sub></i> are constant
-/// >   expressions that evaluate to a boolean value.
-/// >   </span>
-/// > * <span>
-/// >   An expression of one of the forms <i>~e</i>, <i>e<sub>1</sub> ^
-/// >   e<sub>2</sub></i>, <i>e<sub>1</sub> &amp; e<sub>2</sub></i>,
-/// >   <i>e<sub>1</sub> | e<sub>2</sub></i>, <i>e<sub>1</sub> &gt;&gt;
-/// >   e<sub>2</sub></i> or <i>e<sub>1</sub> &lt;&lt; e<sub>2</sub></i>, where
-/// >   <i>e</i>, <i>e<sub>1</sub></i> and <i>e<sub>2</sub></i> are constant
-/// >   expressions that evaluate to an integer value or to <b>null</b>.
-/// >   </span>
-/// > * <span>
-/// >   An expression of one of the forms <i>-e</i>, <i>e<sub>1</sub> +
-/// >   e<sub>2</sub></i>, <i>e<sub>1</sub> -e<sub>2</sub></i>,
-/// >   <i>e<sub>1</sub> * e<sub>2</sub></i>, <i>e<sub>1</sub> /
-/// >   e<sub>2</sub></i>, <i>e<sub>1</sub> ~/ e<sub>2</sub></i>,
-/// >   <i>e<sub>1</sub> &gt; e<sub>2</sub></i>, <i>e<sub>1</sub> &lt;
-/// >   e<sub>2</sub></i>, <i>e<sub>1</sub> &gt;= e<sub>2</sub></i>,
-/// >   <i>e<sub>1</sub> &lt;= e<sub>2</sub></i> or <i>e<sub>1</sub> %
-/// >   e<sub>2</sub></i>, where <i>e</i>, <i>e<sub>1</sub></i> and
-/// >   <i>e<sub>2</sub></i> are constant expressions that evaluate to a numeric
-/// >   value or to <b>null</b>.
-/// >   </span>
-/// > * <span>
-/// >   An expression of the form <i>e<sub>1</sub> ? e<sub>2</sub> :
-/// >   e<sub>3</sub></i> where <i>e<sub>1</sub></i>, <i>e<sub>2</sub></i> and
-/// >   <i>e<sub>3</sub></i> are constant expressions, and <i>e<sub>1</sub></i>
-/// >   evaluates to a boolean value.
-/// >   </span>
-///
-/// 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?
@@ skipping 749 matching lines @@
   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 {
@@ skipping 207 matching lines @@
   @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);
-  }
-}
-
-/**
- * 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 visitPartOfDirective(PartOfDirective node) => node.element;
-
-  @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.
@@ skipping 1709 matching lines @@
     _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 ::=
+ * > functionExpressionInvocation ::=
  * >     [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
@@ skipping 335 matching lines @@
   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 visitConfiguration(Configuration node) => visitNode(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 visitDottedName(DottedName node) => visitNode(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.
    */
@@ skipping 96 matching lines @@
    */
   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;
-
-  @override
-  // TODO(paulberry): add commas.
-  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;
-
-  @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,
-      List<Configuration> configurations,
-      this.deferredKeyword,
-      this.asKeyword,
-      SimpleIdentifier prefix,
-      List<Combinator> combinators,
-      Token semicolon)
-      : super(comment, metadata, keyword, libraryUri, configurations,
-            combinators, semicolon) {
-    _prefix = _becomeParentOf(prefix);
-  }
-
-  @override
-  Iterable get childEntities => super._childEntities
-    ..add(_uri)
-    ..add(deferredKeyword)
-    ..add(asKeyword)
-    ..add(_prefix)
-    ..addAll(combinators)
-    ..add(semicolon);
-
-  @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.comma),
-      _cloneNode(node.message),
-      _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
-  Configuration visitConfiguration(Configuration node) => new Configuration(
-      _mapToken(node.ifKeyword),
-      _mapToken(node.leftParenthesis),
-      _cloneNode(node.name),
-      _mapToken(node.equalToken),
-      _cloneNode(node.value),
-      _mapToken(node.rightParenthesis),
-      _cloneNode(node.libraryUri));
-
-  @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
-  DottedName visitDottedName(DottedName node) =>
-      new DottedName(_cloneNodeList(node.components));
-
-  @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.configurations),
-        _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),
-          _cloneNodeList(node.configurations),
-          _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;
-
-  /**
-   * 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;
-  }
-
-  /**
-   * 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 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;
-
-  @override
-  // TODO(paulberry): add "." tokens.
-  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;
-  }
-
-  @override
-  // TODO(paulberry): add commas.
-  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;
-  }
-
-  @override
-  // TODO(paulberry): add commas.
-  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);
-  }
-
-  @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 configurations used to control which library will actually be loaded at
-   * run-time.
-   */
-  NodeList<Configuration> _configurations;
-
-  /**
-   * 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<Configuration> configurations,
-      List<Combinator> combinators,
-      this.semicolon)
-      : super(comment, metadata, libraryUri) {
-    _configurations = new NodeList<Configuration>(this, configurations);
-    _combinators = new NodeList<Combinator>(this, combinators);
-  }
-
-  /**
-   * Return the combinators used to control how names are imported or exported.
-   */
-  NodeList<Combinator> get combinators => _combinators;
-
-  /**
-   * Return the configurations used to control which library will actually be
-   * loaded at run-time.
-   */
-  NodeList<Configuration> get configurations => _configurations;
-
-  @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;
-
-  /**
-   * Return the name of the native object that implements the class.
-   */
-  StringLiteral get name => _name;
-
-  /**
-   * Set 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 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.
-  @override
-  void set length(int newLength) {
-    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;
-  }
-}
-
-/**
- * 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;
-
-  /**
-   * 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 object used to locate the [AstNode] associated with a source range.
- * More specifically, they will return the deepest [AstNode] which completely
- * encompasses the specified range.
- */
-class NodeLocator2 extends UnifyingAstVisitor<Object> {
-  /**
-   * The inclusive start offset of the range used to identify the node.
-   */
-  int _startOffset = 0;
-
-  /**
-   * The inclusive end offset of the range used to identify the node.
-   */
-  int _endOffset = 0;
-
-  /**
-   * The found node or `null` if there is no such node.
-   */
-  AstNode _foundNode;
-
-  /**
-   * Initialize a newly created locator to locate the deepest [AstNode] for
-   * which `node.offset <= [startOffset]` and `[endOffset] < node.end`.
-   *
-   * If [endOffset] is not provided, then it is considered the same as the
-   * given [startOffset].
-   */
-  NodeLocator2(int startOffset, [int endOffset])
-      : this._startOffset = startOffset,
-        this._endOffset = endOffset == null ? startOffset : endOffset;
-
-  /**
-   * Search within the given AST [node] and return the node that was found,
-   * or `null` if no node was found.
-   */
-  AstNode searchWithin(AstNode node) {
-    if (node == null) {
-      return null;
-    }
-    try {
-      node.accept(this);
-    } on NodeLocator_NodeFoundException {} 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;
-    }
-    if (identical(node._message, _oldNode)) {
-      node.message = _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 visitConfiguration(Configuration node) {
-    if (identical(node.name, _oldNode)) {
-      node.name = _newNode as DottedName;
-      return true;
-    } else if (identical(node.value, _oldNode)) {
-      node.value = _newNode as StringLiteral;
-      return true;
-    } else if (identical(node.libraryUri, _oldNode)) {
-      node.libraryUri = _newNode as StringLiteral;
-      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 visitDottedName(DottedName node) {
-    if (_replaceInList(node.components)) {
-      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;
+   * 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(_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);
+    ..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(_expression, visitor);
+    _safelyVisitChild(_condition, visitor);
+    _safelyVisitChild(_thenStatement, visitor);
+    _safelyVisitChild(_elseStatement, visitor);
   }
 }
 
 /**
- * A part directive.
+ * The "implements" clause in an class declaration.
  *
- * > partDirective ::=
- * >     [Annotation] 'part' [StringLiteral] ';'
+ * > implementsClause ::=
+ * >     'implements' [TypeName] (',' [TypeName])*
  */
-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;
-
-  @override
-  CompilationUnitElement get uriElement => element as CompilationUnitElement;
-
-  @override
-  accept(AstVisitor visitor) => visitor.visitPartDirective(this);
+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;
+
+  @override
+  // TODO(paulberry): add commas.
+  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;
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitImplementsClause(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _interfaces.accept(visitor);
+  }
 }
 
 /**
- * A part-of directive.
+ * An import directive.
  *
- * > partOfDirective ::=
- * >     [Annotation] 'part' 'of' [Identifier] ';'
+ * > importDirective ::=
+ * >     [Annotation] 'import' [StringLiteral] ('as' identifier)? [Combinator]* ';'
+ * >   | [Annotation] 'import' [StringLiteral] 'deferred' 'as' identifier [Combinator]* ';'
  */
-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);
+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,
+      List<Configuration> configurations,
+      this.deferredKeyword,
+      this.asKeyword,
+      SimpleIdentifier prefix,
+      List<Combinator> combinators,
+      Token semicolon)
+      : super(comment, metadata, keyword, libraryUri, configurations,
+            combinators, semicolon) {
+    _prefix = _becomeParentOf(prefix);
   }
 
   @override
   Iterable get childEntities => super._childEntities
-    ..add(partKeyword)
-    ..add(ofKeyword)
-    ..add(_libraryName)
+    ..add(_uri)
+    ..add(deferredKeyword)
+    ..add(asKeyword)
+    ..add(_prefix)
+    ..addAll(combinators)
     ..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);
-  }
-
-  @override
-  accept(AstVisitor visitor) => visitor.visitPartOfDirective(this);
+  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(_libraryName, visitor);
+    _safelyVisitChild(_prefix, visitor);
+    combinators.accept(visitor);
   }
 }
 
 /**
- * A postfix unary expression.
+ * An index expression.
  *
- * > postfixExpression ::=
- * >     [Expression] [Token]
+ * > indexExpression ::=
+ * >     [Expression] '[' [Expression] ']'
  */
-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.
+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;
 
   /**
-   * 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;
+   * 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(_operand)..add(operator);
+  Iterable get childEntities => new ChildEntities()
+    ..add(_target)
+    ..add(period)
+    ..add(leftBracket)
+    ..add(_index)
+    ..add(rightBracket);
 
   @override
-  Token get endToken => operator;
+  Token get endToken => rightBracket;
 
   /**
-   * Return the expression computing the operand for the operator.
+   * Return the expression used to compute the index.
    */
-  Expression get operand => _operand;
+  Expression get index => _index;
 
   /**
-   * Set the expression computing the operand for the operator to the given
-   * [expression].
+   * Set the expression used to compute the index to the given [expression].
    */
-  void set operand(Expression expression) {
-    _operand = _becomeParentOf(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;
 
   /**
+   * 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;
+  }
+
+  /**
+   * 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 operand will
-   * be bound. Otherwise, return `null`.
+   * element representing the parameter to which the value of the index
+   * expression will be bound. Otherwise, return `null`.
    */
-  ParameterElement get _propagatedParameterElementForOperand {
+  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 operand will be bound.
-   * Otherwise, return `null`.
+   * representing the parameter to which the value of the index expression will
+   * be bound. Otherwise, return `null`.
    */
-  ParameterElement get _staticParameterElementForOperand {
+  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.visitPostfixExpression(this);
+  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(_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;
+    _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
+ * >   | hexadecimalIntegerLiteral
+ * >
+ * > decimalIntegerLiteral ::=
+ * >     decimalDigit+
+ * >
+ * > hexadecimalIntegerLiteral ::=
+ * >     '0x' hexadecimalDigit+
+ * >   | '0X' hexadecimalDigit+
+ */
+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 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.
    */
-  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;
-  }
+  LibraryIdentifier(List<SimpleIdentifier> components) {
+    _components = new NodeList<SimpleIdentifier>(this, components);
+  }
+
+  @override
+  Token get beginToken => _components.beginToken;
+
+  @override
+  Element get bestElement => staticElement;
+
+  @override
+  // TODO(paulberry): add "." tokens.
+  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;
+  }
+
+  @override
+  // TODO(paulberry): add commas.
+  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;
+  }
+
+  @override
+  // TODO(paulberry): add commas.
+  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(_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);
+      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(_prefix, visitor);
-    _safelyVisitChild(_identifier, visitor);
-  }
-}
-
-/**
- * A prefix unary expression.
- *
- * > prefixExpression ::=
- * >     [Token] [Expression]
- */
-class PrefixExpression extends Expression {
-  /**
-   * The prefix operator being applied to the operand.
+    _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.
+ *
+ * > methodInvocation ::=
+ * >     ([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 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`.
-   */
-  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) {
+   * 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);
-    _propertyName = _becomeParentOf(propertyName);
+    _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;
-    }
-    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;
+    } 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);
+  }
+
   @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 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 configurations used to control which library will actually be loaded at
+   * run-time.
+   */
+  NodeList<Configuration> _configurations;
+
+  /**
+   * 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<Configuration> configurations,
+      List<Combinator> combinators,
+      this.semicolon)
+      : super(comment, metadata, libraryUri) {
+    _configurations = new NodeList<Configuration>(this, configurations);
+    _combinators = new NodeList<Combinator>(this, combinators);
+  }
+
+  /**
+   * Return the combinators used to control how names are imported or exported.
+   */
+  NodeList<Combinator> get combinators => _combinators;
+
+  /**
+   * Return the configurations used to control which library will actually be
+   * loaded at run-time.
+   */
+  NodeList<Configuration> get configurations => _configurations;
+
+  @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;
+
+  /**
+   * Return the name of the native object that implements the class.
+   */
+  StringLiteral get name => _name;
+
+  /**
+   * Set 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 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.
+  @override
+  void set length(int newLength) {
+    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;
+  }
+}
+
+/**
+ * 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;
+
+  @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);
+  }
+
+  @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`.
+   */
+  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`.
+   */
+  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 visitConfiguration(Configuration 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 visitDottedName(DottedName 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;
-
-  @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;
-
-  @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);
-  }
-
-  @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);
-  }
-
-  @override
-  // TODO(paulberry): add commas.
-  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 visitConfiguration(Configuration 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 visitDottedName(DottedName 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;
-
-  /**
-   * Return `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;
-
-  /**
-   * 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.
-   */
-  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.
+   * 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.
    */
-  SuperConstructorInvocation(this.superKeyword, this.period,
+  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 => superKeyword;
+  Token get beginToken => thisKeyword;
 
   @override
   Iterable get childEntities => new ChildEntities()
-    ..add(superKeyword)
+    ..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;
 
   @override
-  accept(AstVisitor visitor) => visitor.visitSuperConstructorInvocation(this);
+  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;
+
+  @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);
+  }
+
+  @override
+  accept(AstVisitor visitor) => visitor.visitReturnStatement(this);
+
+  @override
+  void visitChildren(AstVisitor visitor) {
+    _safelyVisitChild(_expression, visitor);
+  }
+}
+
+/**
+ * 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);
+  }
+
+  @override
+  // TODO(paulberry): add commas.
+  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);
+  }
+}
+
+/**
+ * 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;
+
+  /**
+   * Return `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;
+
+  /**
+   * 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 quotes (' or ''').
+   * Return `false` if this string literal uses double quotes (" 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.
+   */
+  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;
+
+  @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;
@@ skipping 483 matching lines @@
   @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);
-    if (node.message != null) {
-      _writer.print(', ');
-      _visitNode(node.message);
-    }
-    _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);
-    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 visitConfiguration(Configuration node) {
-    _writer.print('if (');
-    _visitNode(node.name);
-    _visitNodeWithPrefix(" == ", node.value);
-    _writer.print(') ');
-    _visitNode(node.libraryUri);
-    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 visitDottedName(DottedName node) {
-    _visitNodeListWithSeparator(node.components, ".");
-    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) {
-    _visitNodeListWithSeparatorAndSuffix(node.metadata, ' ', ' ');
-    _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) {
-    _visitNodeListWithSeparatorAndSuffix(node.metadata, ' ', ' ');
-    _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) {
-    _visitNodeListWithSeparatorAndSuffix(node.metadata, ' ', ' ');
-    _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 {
@@ skipping 489 matching lines @@
   @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 visitConfiguration(Configuration 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 visitDottedName(DottedName 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
@@ skipping 145 matching lines @@
     _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
+   * 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;
@@ skipping 452 matching lines @@
   }
 
   @override
   accept(AstVisitor visitor) => visitor.visitYieldStatement(this);
 
   @override
   void visitChildren(AstVisitor visitor) {
     _safelyVisitChild(_expression, visitor);
   }
 }