Move class DeclarationResolver to its own file.

pkg/analyzer/lib/src/generated/resolver.dart

Index: pkg/analyzer/lib/src/generated/resolver.dart
diff --git a/pkg/analyzer/lib/src/generated/resolver.dart b/pkg/analyzer/lib/src/generated/resolver.dart
index 3e1dc6bfb3ff04166ad35619c0e6ca7e38eda4ec..d9dd238ffc742a17039405ce7c3886eab33f51dd 100644
--- a/pkg/analyzer/lib/src/generated/resolver.dart
+++ b/pkg/analyzer/lib/src/generated/resolver.dart
@@ -19,7 +19,6 @@ import 'package:analyzer/src/dart/ast/ast.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/dart/element/utilities.dart';
 import 'package:analyzer/src/dart/resolver/inheritance_manager.dart';
 import 'package:analyzer/src/dart/resolver/scope.dart';
 import 'package:analyzer/src/error/codes.dart';
@@ -2267,658 +2266,6 @@ class DeadCodeVerifier extends RecursiveAstVisitor<Object> {
 }
 
 /**
- * A visitor that resolves declarations in an AST structure to already built
- * elements.
- *
- * The resulting AST must have everything resolved that would have been resolved
- * by a [CompilationUnitBuilder] (that is, must be a valid [RESOLVED_UNIT1]).
- * This class must not assume that the [CompilationUnitElement] passed to it is
- * any more complete than a [COMPILATION_UNIT_ELEMENT].
- */
-class DeclarationResolver extends RecursiveAstVisitor<Object>
-    with ExistingElementResolver {
-  /**
-   * The analysis context containing the sources to be analyzed.
-   */
-  AnalysisContext _context;
-
-  /**
-   * The elements that are reachable from the compilation unit element. When a
-   * compilation unit has been resolved, this set should be empty.
-   */
-  Set<Element> _expectedElements;
-
-  /**
-   * The function type alias containing the AST nodes being visited, or `null`
-   * if we are not in the scope of a function type alias.
-   */
-  FunctionTypeAliasElement _enclosingAlias;
-
-  /**
-   * The class containing the AST nodes being visited, or `null` if we are not
-   * in the scope of a class.
-   */
-  ClassElement _enclosingClass;
-
-  /**
-   * The method or function containing the AST nodes being visited, or `null` if
-   * we are not in the scope of a method or function.
-   */
-  ExecutableElement _enclosingExecutable;
-
-  /**
-   * The parameter containing the AST nodes being visited, or `null` if we are
-   * not in the scope of a parameter.
-   */
-  ParameterElement _enclosingParameter;
-
-  /**
-   * Resolve the declarations within the given compilation [unit] to the
-   * elements rooted at the given [element]. Throw an [ElementMismatchException]
-   * if the element model and compilation unit do not match each other.
-   */
-  void resolve(CompilationUnit unit, CompilationUnitElement element) {
-    _context = element.context;
-    ElementGatherer gatherer = new ElementGatherer();
-    element.accept(gatherer);
-    _expectedElements = gatherer.elements;
-    _enclosingUnit = element;
-    _expectedElements.remove(element);
-    unit.element = element;
-    unit.accept(this);
-    _validateResolution();
-  }
-
-  @override
-  Object visitCatchClause(CatchClause node) {
-    SimpleIdentifier exceptionParameter = node.exceptionParameter;
-    if (exceptionParameter != null) {
-      List<LocalVariableElement> localVariables =
-          _enclosingExecutable.localVariables;
-      _findIdentifier(localVariables, exceptionParameter);
-      SimpleIdentifier stackTraceParameter = node.stackTraceParameter;
-      if (stackTraceParameter != null) {
-        _findIdentifier(localVariables, stackTraceParameter);
-      }
-    }
-    return super.visitCatchClause(node);
-  }
-
-  @override
-  Object visitClassDeclaration(ClassDeclaration node) {
-    ClassElement outerClass = _enclosingClass;
-    try {
-      SimpleIdentifier className = node.name;
-      _enclosingClass = _findIdentifier(_enclosingUnit.types, className);
-      super.visitClassDeclaration(node);
-      _resolveMetadata(node, node.metadata, _enclosingClass);
-      return null;
-    } finally {
-      _enclosingClass = outerClass;
-    }
-  }
-
-  @override
-  Object visitClassTypeAlias(ClassTypeAlias node) {
-    ClassElement outerClass = _enclosingClass;
-    try {
-      SimpleIdentifier className = node.name;
-      _enclosingClass = _findIdentifier(_enclosingUnit.types, className);
-      super.visitClassTypeAlias(node);
-      _resolveMetadata(node, node.metadata, _enclosingClass);
-      return null;
-    } finally {
-      _enclosingClass = outerClass;
-    }
-  }
-
-  @override
-  Object visitConstructorDeclaration(ConstructorDeclaration node) {
-    ExecutableElement outerExecutable = _enclosingExecutable;
-    try {
-      SimpleIdentifier constructorName = node.name;
-      if (constructorName == null) {
-        _enclosingExecutable = _enclosingClass.unnamedConstructor;
-        if (_enclosingExecutable == null) {
-          _mismatch('Could not find default constructor', node);
-        }
-      } else {
-        _enclosingExecutable =
-            _enclosingClass.getNamedConstructor(constructorName.name);
-        if (_enclosingExecutable == null) {
-          _mismatch(
-              'Could not find constructor element with name "${constructorName.name}',
-              node);
-        }
-        constructorName.staticElement = _enclosingExecutable;
-      }
-      _expectedElements.remove(_enclosingExecutable);
-      node.element = _enclosingExecutable as ConstructorElement;
-      super.visitConstructorDeclaration(node);
-      _resolveMetadata(node, node.metadata, _enclosingExecutable);
-      return null;
-    } finally {
-      _enclosingExecutable = outerExecutable;
-    }
-  }
-
-  @override
-  Object visitDeclaredIdentifier(DeclaredIdentifier node) {
-    SimpleIdentifier variableName = node.identifier;
-    Element element =
-        _findIdentifier(_enclosingExecutable.localVariables, variableName);
-    super.visitDeclaredIdentifier(node);
-    _resolveMetadata(node, node.metadata, element);
-    return null;
-  }
-
-  @override
-  Object visitDefaultFormalParameter(DefaultFormalParameter node) {
-    SimpleIdentifier parameterName = node.parameter.identifier;
-    ParameterElement element = _getElementForParameter(node, parameterName);
-    Expression defaultValue = node.defaultValue;
-    if (defaultValue != null) {
-      ExecutableElement outerExecutable = _enclosingExecutable;
-      try {
-        _enclosingExecutable = element.initializer;
-        defaultValue.accept(this);
-      } finally {
-        _enclosingExecutable = outerExecutable;
-      }
-    }
-    ParameterElement outerParameter = _enclosingParameter;
-    try {
-      _enclosingParameter = element;
-      super.visitDefaultFormalParameter(node);
-      _resolveMetadata(node, node.metadata, element);
-      return null;
-    } finally {
-      _enclosingParameter = outerParameter;
-    }
-  }
-
-  @override
-  Object visitEnumDeclaration(EnumDeclaration node) {
-    ClassElement enclosingEnum =
-        _findIdentifier(_enclosingUnit.enums, node.name);
-    List<FieldElement> constants = enclosingEnum.fields;
-    for (EnumConstantDeclaration constant in node.constants) {
-      _findIdentifier(constants, constant.name);
-    }
-    super.visitEnumDeclaration(node);
-    _resolveMetadata(node, node.metadata, enclosingEnum);
-    return null;
-  }
-
-  @override
-  Object visitExportDirective(ExportDirective node) {
-    super.visitExportDirective(node);
-    _resolveAnnotations(
-        node, node.metadata, _enclosingUnit.getAnnotations(node.offset));
-    return null;
-  }
-
-  @override
-  Object visitFieldDeclaration(FieldDeclaration node) {
-    super.visitFieldDeclaration(node);
-    _resolveMetadata(node, node.metadata, node.fields.variables[0].element);
-    return null;
-  }
-
-  @override
-  Object visitFieldFormalParameter(FieldFormalParameter node) {
-    if (node.parent is! DefaultFormalParameter) {
-      SimpleIdentifier parameterName = node.identifier;
-      ParameterElement element = _getElementForParameter(node, parameterName);
-      ParameterElement outerParameter = _enclosingParameter;
-      try {
-        _enclosingParameter = element;
-        super.visitFieldFormalParameter(node);
-        _resolveMetadata(node, node.metadata, element);
-        return null;
-      } finally {
-        _enclosingParameter = outerParameter;
-      }
-    } else {
-      return super.visitFieldFormalParameter(node);
-    }
-  }
-
-  @override
-  Object visitFunctionDeclaration(FunctionDeclaration node) {
-    ExecutableElement outerExecutable = _enclosingExecutable;
-    try {
-      SimpleIdentifier functionName = node.name;
-      Token property = node.propertyKeyword;
-      if (property == null) {
-        if (_enclosingExecutable != null) {
-          _enclosingExecutable =
-              _findIdentifier(_enclosingExecutable.functions, functionName);
-        } else {
-          _enclosingExecutable =
-              _findIdentifier(_enclosingUnit.functions, functionName);
-        }
-      } else {
-        if (_enclosingExecutable != null) {
-          _enclosingExecutable =
-              _findIdentifier(_enclosingExecutable.functions, functionName);
-        } else {
-          List<PropertyAccessorElement> accessors;
-          if (_enclosingClass != null) {
-            accessors = _enclosingClass.accessors;
-          } else {
-            accessors = _enclosingUnit.accessors;
-          }
-          PropertyAccessorElement accessor;
-          if (property.keyword == Keyword.GET) {
-            accessor = _findIdentifier(accessors, functionName);
-          } else if (property.keyword == Keyword.SET) {
-            accessor = _findWithNameAndOffset(accessors, functionName,
-                functionName.name + '=', functionName.offset);
-            _expectedElements.remove(accessor);
-            functionName.staticElement = accessor;
-          }
-          _enclosingExecutable = accessor;
-        }
-      }
-      node.functionExpression.element = _enclosingExecutable;
-      super.visitFunctionDeclaration(node);
-      _resolveMetadata(node, node.metadata, _enclosingExecutable);
-      return null;
-    } finally {
-      _enclosingExecutable = outerExecutable;
-    }
-  }
-
-  @override
-  Object visitFunctionExpression(FunctionExpression node) {
-    if (node.parent is! FunctionDeclaration) {
-      FunctionElement element = _findAtOffset(
-          _enclosingExecutable.functions, node, node.beginToken.offset);
-      _expectedElements.remove(element);
-      node.element = element;
-    }
-    ExecutableElement outerExecutable = _enclosingExecutable;
-    try {
-      _enclosingExecutable = node.element;
-      return super.visitFunctionExpression(node);
-    } finally {
-      _enclosingExecutable = outerExecutable;
-    }
-  }
-
-  @override
-  Object visitFunctionTypeAlias(FunctionTypeAlias node) {
-    FunctionTypeAliasElement outerAlias = _enclosingAlias;
-    try {
-      SimpleIdentifier aliasName = node.name;
-      _enclosingAlias =
-          _findIdentifier(_enclosingUnit.functionTypeAliases, aliasName);
-      super.visitFunctionTypeAlias(node);
-      _resolveMetadata(node, node.metadata, _enclosingAlias);
-      return null;
-    } finally {
-      _enclosingAlias = outerAlias;
-    }
-  }
-
-  @override
-  Object visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
-    if (node.parent is! DefaultFormalParameter) {
-      SimpleIdentifier parameterName = node.identifier;
-      ParameterElement element = _getElementForParameter(node, parameterName);
-      ParameterElement outerParameter = _enclosingParameter;
-      try {
-        _enclosingParameter = element;
-        super.visitFunctionTypedFormalParameter(node);
-        _resolveMetadata(node, node.metadata, _enclosingParameter);
-        return null;
-      } finally {
-        _enclosingParameter = outerParameter;
-      }
-    } else {
-      return super.visitFunctionTypedFormalParameter(node);
-    }
-  }
-
-  @override
-  Object visitImportDirective(ImportDirective node) {
-    super.visitImportDirective(node);
-    _resolveAnnotations(
-        node, node.metadata, _enclosingUnit.getAnnotations(node.offset));
-    return null;
-  }
-
-  @override
-  Object visitLabeledStatement(LabeledStatement node) {
-    for (Label label in node.labels) {
-      SimpleIdentifier labelName = label.label;
-      _findIdentifier(_enclosingExecutable.labels, labelName);
-    }
-    return super.visitLabeledStatement(node);
-  }
-
-  @override
-  Object visitLibraryDirective(LibraryDirective node) {
-    super.visitLibraryDirective(node);
-    _resolveAnnotations(
-        node, node.metadata, _enclosingUnit.getAnnotations(node.offset));
-    return null;
-  }
-
-  @override
-  Object visitMethodDeclaration(MethodDeclaration node) {
-    ExecutableElement outerExecutable = _enclosingExecutable;
-    try {
-      Token property = node.propertyKeyword;
-      SimpleIdentifier methodName = node.name;
-      String nameOfMethod = methodName.name;
-      if (property == null) {
-        String elementName = nameOfMethod == '-' &&
-                node.parameters != null &&
-                node.parameters.parameters.isEmpty
-            ? 'unary-'
-            : nameOfMethod;
-        _enclosingExecutable = _findWithNameAndOffset(_enclosingClass.methods,
-            methodName, elementName, methodName.offset);
-        _expectedElements.remove(_enclosingExecutable);
-        methodName.staticElement = _enclosingExecutable;
-      } else {
-        PropertyAccessorElement accessor;
-        if (property.keyword == Keyword.GET) {
-          accessor = _findIdentifier(_enclosingClass.accessors, methodName);
-        } else if (property.keyword == Keyword.SET) {
-          accessor = _findWithNameAndOffset(_enclosingClass.accessors,
-              methodName, nameOfMethod + '=', methodName.offset);
-          _expectedElements.remove(accessor);
-          methodName.staticElement = accessor;
-        }
-        _enclosingExecutable = accessor;
-      }
-      super.visitMethodDeclaration(node);
-      _resolveMetadata(node, node.metadata, _enclosingExecutable);
-      return null;
-    } finally {
-      _enclosingExecutable = outerExecutable;
-    }
-  }
-
-  @override
-  Object visitPartDirective(PartDirective node) {
-    super.visitPartDirective(node);
-    _resolveAnnotations(
-        node, node.metadata, _enclosingUnit.getAnnotations(node.offset));
-    return null;
-  }
-
-  @override
-  Object visitPartOfDirective(PartOfDirective node) {
-    node.element = _enclosingUnit.library;
-    return super.visitPartOfDirective(node);
-  }
-
-  @override
-  Object visitSimpleFormalParameter(SimpleFormalParameter node) {
-    if (node.parent is! DefaultFormalParameter) {
-      SimpleIdentifier parameterName = node.identifier;
-      ParameterElement element = _getElementForParameter(node, parameterName);
-      ParameterElement outerParameter = _enclosingParameter;
-      try {
-        _enclosingParameter = element;
-        super.visitSimpleFormalParameter(node);
-        _resolveMetadata(node, node.metadata, element);
-        return null;
-      } finally {
-        _enclosingParameter = outerParameter;
-      }
-    } else {}
-    return super.visitSimpleFormalParameter(node);
-  }
-
-  @override
-  Object visitSwitchCase(SwitchCase node) {
-    for (Label label in node.labels) {
-      SimpleIdentifier labelName = label.label;
-      _findIdentifier(_enclosingExecutable.labels, labelName);
-    }
-    return super.visitSwitchCase(node);
-  }
-
-  @override
-  Object visitSwitchDefault(SwitchDefault node) {
-    for (Label label in node.labels) {
-      SimpleIdentifier labelName = label.label;
-      _findIdentifier(_enclosingExecutable.labels, labelName);
-    }
-    return super.visitSwitchDefault(node);
-  }
-
-  @override
-  Object visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
-    super.visitTopLevelVariableDeclaration(node);
-    _resolveMetadata(node, node.metadata, node.variables.variables[0].element);
-    return null;
-  }
-
-  @override
-  Object visitTypeParameter(TypeParameter node) {
-    SimpleIdentifier parameterName = node.name;
-    Element element = null;
-    if (_enclosingExecutable != null) {
-      element = _findIdentifier(
-          _enclosingExecutable.typeParameters, parameterName,
-          required: false);
-    }
-    if (element == null) {
-      if (_enclosingClass != null) {
-        element =
-            _findIdentifier(_enclosingClass.typeParameters, parameterName);
-      } else if (_enclosingAlias != null) {
-        element =
-            _findIdentifier(_enclosingAlias.typeParameters, parameterName);
-      }
-    }
-    if (element == null) {
-      String name = parameterName.name;
-      int offset = parameterName.offset;
-      _mismatch(
-          'Could not find type parameter with name "$name" at $offset', node);
-    }
-    super.visitTypeParameter(node);
-    _resolveMetadata(node, node.metadata, element);
-    return null;
-  }
-
-  @override
-  Object visitVariableDeclaration(VariableDeclaration node) {
-    VariableElement element = null;
-    SimpleIdentifier variableName = node.name;
-    if (_enclosingExecutable != null) {
-      element = _findIdentifier(
-          _enclosingExecutable.localVariables, variableName,
-          required: false);
-    }
-    if (element == null && _enclosingClass != null) {
-      element = _findIdentifier(_enclosingClass.fields, variableName,
-          required: false);
-    }
-    if (element == null && _enclosingUnit != null) {
-      element = _findIdentifier(_enclosingUnit.topLevelVariables, variableName);
-    }
-    Expression initializer = node.initializer;
-    if (initializer != null) {
-      ExecutableElement outerExecutable = _enclosingExecutable;
-      try {
-        _enclosingExecutable = element.initializer;
-        return super.visitVariableDeclaration(node);
-      } finally {
-        _enclosingExecutable = outerExecutable;
-      }
-    }
-    return super.visitVariableDeclaration(node);
-  }
-
-  @override
-  Object visitVariableDeclarationList(VariableDeclarationList node) {
-    super.visitVariableDeclarationList(node);
-    if (node.parent is! FieldDeclaration &&
-        node.parent is! TopLevelVariableDeclaration) {
-      _resolveMetadata(node, node.metadata, node.variables[0].element);
-    }
-    return null;
-  }
-
-  /**
-   * Return the element in the given list of [elements] that was created for the
-   * declaration at the given [offset]. Throw an [ElementMismatchException] if
-   * an element at that offset cannot be found.
-   *
-   * This method should only be used when there is no name associated with the
-   * node.
-   */
-  Element _findAtOffset(List<Element> elements, AstNode node, int offset) =>
-      _findWithNameAndOffset(elements, node, '', offset);
-
-  /**
-   * Return the element in the given list of [elements] that was created for the
-   * declaration with the given [identifier]. As a side-effect, associate the
-   * returned element with the identifier. Throw an [ElementMismatchException]
-   * if an element corresponding to the identifier cannot be found unless
-   * [required] is `false`, in which case return `null`.
-   */
-  Element _findIdentifier(List<Element> elements, SimpleIdentifier identifier,
-      {bool required: true}) {
-    Element element = _findWithNameAndOffset(
-        elements, identifier, identifier.name, identifier.offset,
-        required: required);
-    _expectedElements.remove(element);
-    identifier.staticElement = element;
-    return element;
-  }
-
-  /**
-   * Return the element in the given list of [elements] that was created for the
-   * declaration with the given [name] at the given [offset]. Throw an
-   * [ElementMismatchException] if an element corresponding to the identifier
-   * cannot be found unless [required] is `false`, in which case return `null`.
-   */
-  Element _findWithNameAndOffset(
-      List<Element> elements, AstNode node, String name, int offset,
-      {bool required: true}) {
-    int length = elements.length;
-    for (int i = 0; i < length; i++) {
-      Element element = elements[i];
-      if (element.nameOffset == offset && element.name == name) {
-        return element;
-      }
-    }
-    if (!required) {
-      return null;
-    }
-    for (int i = 0; i < length; i++) {
-      Element element = elements[i];
-      if (element.name == name) {
-        _mismatch(
-            'Found element with name "$name" at ${element.nameOffset}, '
-            'but expected offset of $offset',
-            node);
-      }
-      if (element.nameOffset == offset) {
-        _mismatch(
-            'Found element with name "${element.name}" at $offset, '
-            'but expected element with name "$name"',
-            node);
-      }
-    }
-    _mismatch('Could not find element with name "$name" at $offset', node);
-    return null; // Never reached
-  }
-
-  /**
-   * Search the most closely enclosing list of parameter elements for a
-   * parameter, defined by the given [node], with the given [parameterName].
-   * Return the element that was found, or throw an [ElementMismatchException]
-   * if an element corresponding to the identifier cannot be found.
-   */
-  ParameterElement _getElementForParameter(
-      FormalParameter node, SimpleIdentifier parameterName) {
-    List<ParameterElement> parameters = null;
-    if (_enclosingParameter != null) {
-      parameters = _enclosingParameter.parameters;
-    }
-    if (parameters == null && _enclosingExecutable != null) {
-      parameters = _enclosingExecutable.parameters;
-    }
-    if (parameters == null && _enclosingAlias != null) {
-      parameters = _enclosingAlias.parameters;
-    }
-    if (parameters == null) {
-      StringBuffer buffer = new StringBuffer();
-      buffer.writeln('Could not find parameter in enclosing scope');
-      buffer.writeln(
-          '(_enclosingParameter == null) == ${_enclosingParameter == null}');
-      buffer.writeln(
-          '(_enclosingExecutable == null) == ${_enclosingExecutable == null}');
-      buffer.writeln('(_enclosingAlias == null) == ${_enclosingAlias == null}');
-      _mismatch(buffer.toString(), parameterName);
-    }
-    return _findIdentifier(parameters, parameterName);
-  }
-
-  /**
-   * Associate each of the annotation [nodes] with the corresponding
-   * [ElementAnnotation] in [annotations]. If there is a problem, report it
-   * against the given [parent] node.
-   */
-  void _resolveAnnotations(AstNode parent, NodeList<Annotation> nodes,
-      List<ElementAnnotation> annotations) {
-    int nodeCount = nodes.length;
-    if (nodeCount != annotations.length) {
-      _mismatch(
-          'Found $nodeCount annotation nodes and '
-          '${annotations.length} element annotations',
-          parent);
-    }
-    for (int i = 0; i < nodeCount; i++) {
-      nodes[i].elementAnnotation = annotations[i];
-    }
-  }
-
-  /**
-   * If [element] is not `null`, associate each of the annotation [nodes] with
-   * the corresponding [ElementAnnotation] in [element.metadata]. If there is a
-   * problem, report it against the given [parent] node.
-   *
-   * If [element] is `null`, do nothing--this allows us to be robust in the
-   * case where we are operating on an element model that hasn't been fully
-   * built.
-   */
-  void _resolveMetadata(
-      AstNode parent, NodeList<Annotation> nodes, Element element) {
-    if (element != null) {
-      _resolveAnnotations(parent, nodes, element.metadata);
-    }
-  }
-
-  /**
-   * Throw an exception if there are non-synthetic elements in the element model
-   * that were not associated with an AST node.
-   */
-  void _validateResolution() {
-    if (_expectedElements.isNotEmpty) {
-      StringBuffer buffer = new StringBuffer();
-      buffer.write(_expectedElements.length);
-      buffer.writeln(' unmatched elements found:');
-      for (Element element in _expectedElements) {
-        buffer.write('  ');
-        buffer.writeln(element);
-      }
-      throw new ElementMismatchException(buffer.toString());
-    }
-  }
-}
-
-/**
  * A visitor that resolves directives in an AST structure to already built
  * elements.
  *
@@ -3331,15 +2678,6 @@ class ElementHolder {
   }
 }
 
-class ElementMismatchException extends AnalysisException {
-  /**
-   * Initialize a newly created exception to have the given [message] and
-   * [cause].
-   */
-  ElementMismatchException(String message, [CaughtException cause = null])
-      : super(message, cause);
-}
-
 /**
  * Instances of the class `EnumMemberBuilder` build the members in enum declarations.
  */
@@ -3431,41 +2769,6 @@ class EnumMemberBuilder extends RecursiveAstVisitor<Object> {
 }
 
 /**
- * A mixin for classes that use an existing element model to resolve a portion
- * of an AST structure.
- */
-class ExistingElementResolver {
-  /**
-   * The compilation unit containing the AST nodes being visited.
-   */
-  CompilationUnitElementImpl _enclosingUnit;
-
-  /**
-   * Throw an [ElementMismatchException] to report that the element model and the
-   * AST do not match. The [message] will have the path to the given [node]
-   * appended to it.
-   */
-  void _mismatch(String message, AstNode node) {
-    StringBuffer buffer = new StringBuffer();
-    buffer.write('Mismatch in ');
-    buffer.write(runtimeType);
-    buffer.write(' while resolving ');
-    buffer.writeln(_enclosingUnit?.source?.fullName);
-    buffer.writeln(message);
-    buffer.write('Path to root:');
-    String separator = ' ';
-    AstNode parent = node;
-    while (parent != null) {
-      buffer.write(separator);
-      buffer.write(parent.runtimeType.toString());
-      separator = ', ';
-      parent = parent.parent;
-    }
-    throw new ElementMismatchException(buffer.toString());
-  }
-}
-
-/**
  * Instances of the class `ExitDetector` determine whether the visited AST node is guaranteed
  * to terminate by executing a `return` statement, `throw` expression, `rethrow`
  * expression, or simple infinite loop such as `while(true)`.