Removed fixed dependencies

packages/analyzer/lib/src/dart/resolver/scope.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.dart.resolver.scope;
+
+import 'dart:collection';
+
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/error/error.dart';
+import 'package:analyzer/src/dart/element/element.dart';
+import 'package:analyzer/src/error/codes.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/java_engine.dart';
+import 'package:analyzer/src/generated/source.dart';
+
+/**
+ * The scope defined by a block.
+ */
+class BlockScope extends EnclosedScope {
+  /**
+   * Initialize a newly created scope, enclosed within the [enclosingScope],
+   * based on the given [block].
+   */
+  BlockScope(Scope enclosingScope, Block block) : super(enclosingScope) {
+    if (block == null) {
+      throw new ArgumentError("block cannot be null");
+    }
+    _defineElements(block);
+  }
+
+  void _defineElements(Block block) {
+    for (Element element in elementsInBlock(block)) {
+      define(element);
+    }
+  }
+
+  /**
+   * Return the elements that are declared directly in the given [block]. This
+   * does not include elements declared in nested blocks.
+   */
+  static Iterable<Element> elementsInBlock(Block block) sync* {
+    NodeList<Statement> statements = block.statements;
+    int statementCount = statements.length;
+    for (int i = 0; i < statementCount; i++) {
+      Statement statement = statements[i];
+      if (statement is VariableDeclarationStatement) {
+        NodeList<VariableDeclaration> variables = statement.variables.variables;
+        int variableCount = variables.length;
+        for (int j = 0; j < variableCount; j++) {
+          yield variables[j].element;
+        }
+      } else if (statement is FunctionDeclarationStatement) {
+        yield statement.functionDeclaration.element;
+      }
+    }
+  }
+}
+
+/**
+ * The scope defined by a class.
+ */
+class ClassScope extends EnclosedScope {
+  /**
+   * Initialize a newly created scope, enclosed within the [enclosingScope],
+   * based on the given [classElement].
+   */
+  ClassScope(Scope enclosingScope, ClassElement classElement)
+      : super(enclosingScope) {
+    if (classElement == null) {
+      throw new ArgumentError("class element cannot be null");
+    }
+    _defineMembers(classElement);
+  }
+
+  @override
+  AnalysisError getErrorForDuplicate(Element existing, Element duplicate) {
+    if (existing is PropertyAccessorElement && duplicate is MethodElement) {
+      if (existing.nameOffset < duplicate.nameOffset) {
+        return new AnalysisError(
+            duplicate.source,
+            duplicate.nameOffset,
+            duplicate.nameLength,
+            CompileTimeErrorCode.METHOD_AND_GETTER_WITH_SAME_NAME,
+            [existing.displayName]);
+      } else {
+        return new AnalysisError(
+            existing.source,
+            existing.nameOffset,
+            existing.nameLength,
+            CompileTimeErrorCode.GETTER_AND_METHOD_WITH_SAME_NAME,
+            [existing.displayName]);
+      }
+    }
+    return super.getErrorForDuplicate(existing, duplicate);
+  }
+
+  /**
+   * Define the instance members defined by the given [classElement].
+   */
+  void _defineMembers(ClassElement classElement) {
+    List<PropertyAccessorElement> accessors = classElement.accessors;
+    int accessorLength = accessors.length;
+    for (int i = 0; i < accessorLength; i++) {
+      define(accessors[i]);
+    }
+    List<MethodElement> methods = classElement.methods;
+    int methodLength = methods.length;
+    for (int i = 0; i < methodLength; i++) {
+      define(methods[i]);
+    }
+  }
+}
+
+/**
+ * The scope defined for the initializers in a constructor.
+ */
+class ConstructorInitializerScope extends EnclosedScope {
+  /**
+   * Initialize a newly created scope, enclosed within the [enclosingScope].
+   */
+  ConstructorInitializerScope(Scope enclosingScope, ConstructorElement element)
+      : super(enclosingScope) {
+    _initializeFieldFormalParameters(element);
+  }
+
+  /**
+   * Initialize the local scope with all of the field formal parameters.
+   */
+  void _initializeFieldFormalParameters(ConstructorElement element) {
+    for (ParameterElement parameter in element.parameters) {
+      if (parameter is FieldFormalParameterElement) {
+        define(parameter);
+      }
+    }
+  }
+}
+
+/**
+ * A scope that is lexically enclosed in another scope.
+ */
+class EnclosedScope extends Scope {
+  /**
+   * The scope in which this scope is lexically enclosed.
+   */
+  @override
+  final Scope enclosingScope;
+
+  /**
+   * Initialize a newly created scope, enclosed within the [enclosingScope].
+   */
+  EnclosedScope(this.enclosingScope);
+
+  @override
+  Element internalLookup(
+      Identifier identifier, String name, LibraryElement referencingLibrary) {
+    Element element = localLookup(name, referencingLibrary);
+    if (element != null) {
+      return element;
+    }
+    // Check enclosing scope.
+    return enclosingScope.internalLookup(identifier, name, referencingLibrary);
+  }
+
+  @override
+  Element _internalLookupPrefixed(PrefixedIdentifier identifier, String prefix,
+      String name, LibraryElement referencingLibrary) {
+    return enclosingScope._internalLookupPrefixed(
+        identifier, prefix, name, referencingLibrary);
+  }
+}
+
+/**
+ * The scope defined by a function.
+ */
+class FunctionScope extends EnclosedScope {
+  /**
+   * The element representing the function that defines this scope.
+   */
+  final ExecutableElement _functionElement;
+
+  /**
+   * A flag indicating whether the parameters have already been defined, used to
+   * prevent the parameters from being defined multiple times.
+   */
+  bool _parametersDefined = false;
+
+  /**
+   * Initialize a newly created scope, enclosed within the [enclosingScope],
+   * that represents the given [_functionElement].
+   */
+  FunctionScope(Scope enclosingScope, this._functionElement)
+      : super(new EnclosedScope(new EnclosedScope(enclosingScope))) {
+    if (_functionElement == null) {
+      throw new ArgumentError("function element cannot be null");
+    }
+    _defineTypeParameters();
+  }
+
+  /**
+   * Define the parameters for the given function in the scope that encloses
+   * this function.
+   */
+  void defineParameters() {
+    if (_parametersDefined) {
+      return;
+    }
+    _parametersDefined = true;
+    Scope parameterScope = enclosingScope;
+    List<ParameterElement> parameters = _functionElement.parameters;
+    int length = parameters.length;
+    for (int i = 0; i < length; i++) {
+      ParameterElement parameter = parameters[i];
+      if (!parameter.isInitializingFormal) {
+        parameterScope.define(parameter);
+      }
+    }
+  }
+
+  /**
+   * Define the type parameters for the function.
+   */
+  void _defineTypeParameters() {
+    Scope typeParameterScope = enclosingScope.enclosingScope;
+    List<TypeParameterElement> typeParameters = _functionElement.typeParameters;
+    int length = typeParameters.length;
+    for (int i = 0; i < length; i++) {
+      TypeParameterElement typeParameter = typeParameters[i];
+      typeParameterScope.define(typeParameter);
+    }
+  }
+}
+
+/**
+ * The scope defined by a function type alias.
+ */
+class FunctionTypeScope extends EnclosedScope {
+  final FunctionTypeAliasElement _typeElement;
+
+  bool _parametersDefined = false;
+
+  /**
+   * Initialize a newly created scope, enclosed within the [enclosingScope],
+   * that represents the given [_typeElement].
+   */
+  FunctionTypeScope(Scope enclosingScope, this._typeElement)
+      : super(new EnclosedScope(enclosingScope)) {
+    _defineTypeParameters();
+  }
+
+  /**
+   * Define the parameters for the function type alias.
+   */
+  void defineParameters() {
+    if (_parametersDefined) {
+      return;
+    }
+    _parametersDefined = true;
+    for (ParameterElement parameter in _typeElement.parameters) {
+      define(parameter);
+    }
+  }
+
+  /**
+   * Define the type parameters for the function type alias.
+   */
+  void _defineTypeParameters() {
+    Scope typeParameterScope = enclosingScope;
+    for (TypeParameterElement typeParameter in _typeElement.typeParameters) {
+      typeParameterScope.define(typeParameter);
+    }
+  }
+}
+
+/**
+ * The scope statements that can be the target of unlabeled `break` and
+ * `continue` statements.
+ */
+class ImplicitLabelScope {
+  /**
+   * The implicit label scope associated with the top level of a function.
+   */
+  static const ImplicitLabelScope ROOT = const ImplicitLabelScope._(null, null);
+
+  /**
+   * The implicit label scope enclosing this implicit label scope.
+   */
+  final ImplicitLabelScope outerScope;
+
+  /**
+   * The statement that acts as a target for break and/or continue statements
+   * at this scoping level.
+   */
+  final Statement statement;
+
+  /**
+   * Initialize a newly created scope, enclosed within the [outerScope],
+   * representing the given [statement].
+   */
+  const ImplicitLabelScope._(this.outerScope, this.statement);
+
+  /**
+   * Return the statement which should be the target of an unlabeled `break` or
+   * `continue` statement, or `null` if there is no appropriate target.
+   */
+  Statement getTarget(bool isContinue) {
+    if (outerScope == null) {
+      // This scope represents the toplevel of a function body, so it doesn't
+      // match either break or continue.
+      return null;
+    }
+    if (isContinue && statement is SwitchStatement) {
+      return outerScope.getTarget(isContinue);
+    }
+    return statement;
+  }
+
+  /**
+   * Initialize a newly created scope to represent a switch statement or loop
+   * nested within the current scope.  [statement] is the statement associated
+   * with the newly created scope.
+   */
+  ImplicitLabelScope nest(Statement statement) =>
+      new ImplicitLabelScope._(this, statement);
+}
+
+/**
+ * A scope in which a single label is defined.
+ */
+class LabelScope {
+  /**
+   * The label scope enclosing this label scope.
+   */
+  final LabelScope _outerScope;
+
+  /**
+   * The label defined in this scope.
+   */
+  final String _label;
+
+  /**
+   * The element to which the label resolves.
+   */
+  final LabelElement element;
+
+  /**
+   * The AST node to which the label resolves.
+   */
+  final AstNode node;
+
+  /**
+   * Initialize a newly created scope, enclosed within the [_outerScope],
+   * representing the label [_label]. The [node] is the AST node the label
+   * resolves to. The [element] is the element the label resolves to.
+   */
+  LabelScope(this._outerScope, this._label, this.node, this.element);
+
+  /**
+   * Return the LabelScope which defines [targetLabel], or `null` if it is not
+   * defined in this scope.
+   */
+  LabelScope lookup(String targetLabel) {
+    if (_label == targetLabel) {
+      return this;
+    }
+    return _outerScope?.lookup(targetLabel);
+  }
+}
+
+/**
+ * The scope containing all of the names available from imported libraries.
+ */
+class LibraryImportScope extends Scope {
+  /**
+   * The name of the property containing a list of the elements from the SDK
+   * that conflict with the single name imported from non-SDK libraries. The
+   * value of the property is always of type `List<Element>`.
+   */
+  static const String conflictingSdkElements = 'conflictingSdkElements';
+
+  /**
+   * The element representing the library in which this scope is enclosed.
+   */
+  final LibraryElement _definingLibrary;
+
+  /**
+   * A list of the namespaces representing the names that are available in this scope from imported
+   * libraries.
+   */
+  List<Namespace> _importedNamespaces;
+
+  /**
+   * A table mapping prefixes that have been referenced to a map from the names
+   * that have been referenced to the element associated with the prefixed name.
+   */
+  Map<String, Map<String, Element>> _definedPrefixedNames;
+
+  /**
+   * Initialize a newly created scope representing the names imported into the
+   * [_definingLibrary].
+   */
+  LibraryImportScope(this._definingLibrary) {
+    _createImportedNamespaces();
+  }
+
+  @override
+  void define(Element element) {
+    if (!Scope.isPrivateName(element.displayName)) {
+      super.define(element);
+    }
+  }
+
+  @override
+  Source getSource(AstNode node) {
+    Source source = super.getSource(node);
+    if (source == null) {
+      source = _definingLibrary.definingCompilationUnit.source;
+    }
+    return source;
+  }
+
+  @override
+  Element internalLookup(
+      Identifier identifier, String name, LibraryElement referencingLibrary) {
+    Element element = localLookup(name, referencingLibrary);
+    if (element != null) {
+      return element;
+    }
+    element = _lookupInImportedNamespaces(
+        identifier, (Namespace namespace) => namespace.get(name));
+    if (element != null) {
+      defineNameWithoutChecking(name, element);
+    }
+    return element;
+  }
+
+  @override
+  bool shouldIgnoreUndefined(Identifier node) {
+    Iterable<NamespaceCombinator> getShowCombinators(
+            ImportElement importElement) =>
+        importElement.combinators.where((NamespaceCombinator combinator) =>
+            combinator is ShowElementCombinator);
+    if (node is PrefixedIdentifier) {
+      String prefix = node.prefix.name;
+      String name = node.identifier.name;
+      List<ImportElement> imports = _definingLibrary.imports;
+      int count = imports.length;
+      for (int i = 0; i < count; i++) {
+        ImportElement importElement = imports[i];
+        if (importElement.prefix?.name == prefix &&
+            importElement.importedLibrary?.isSynthetic != false) {
+          Iterable<NamespaceCombinator> showCombinators =
+              getShowCombinators(importElement);
+          if (showCombinators.isEmpty) {
+            return true;
+          }
+          for (ShowElementCombinator combinator in showCombinators) {
+            if (combinator.shownNames.contains(name)) {
+              return true;
+            }
+          }
+        }
+      }
+    } else if (node is SimpleIdentifier) {
+      String name = node.name;
+      List<ImportElement> imports = _definingLibrary.imports;
+      int count = imports.length;
+      for (int i = 0; i < count; i++) {
+        ImportElement importElement = imports[i];
+        if (importElement.prefix == null &&
+            importElement.importedLibrary?.isSynthetic != false) {
+          for (ShowElementCombinator combinator
+              in getShowCombinators(importElement)) {
+            if (combinator.shownNames.contains(name)) {
+              return true;
+            }
+          }
+        }
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Create all of the namespaces associated with the libraries imported into
+   * this library. The names are not added to this scope, but are stored for
+   * later reference.
+   */
+  void _createImportedNamespaces() {
+    NamespaceBuilder builder = new NamespaceBuilder();
+    List<ImportElement> imports = _definingLibrary.imports;
+    int count = imports.length;
+    _importedNamespaces = new List<Namespace>(count);
+    for (int i = 0; i < count; i++) {
+      _importedNamespaces[i] =
+          builder.createImportNamespaceForDirective(imports[i]);
+    }
+  }
+
+  /**
+   * Add the given [element] to this scope without checking for duplication or
+   * hiding.
+   */
+  void _definePrefixedNameWithoutChecking(
+      String prefix, String name, Element element) {
+    _definedPrefixedNames ??= new HashMap<String, Map<String, Element>>();
+    Map<String, Element> unprefixedNames = _definedPrefixedNames.putIfAbsent(
+        prefix, () => new HashMap<String, Element>());
+    unprefixedNames[name] = element;
+  }
+
+  @override
+  Element _internalLookupPrefixed(PrefixedIdentifier identifier, String prefix,
+      String name, LibraryElement referencingLibrary) {
+    Element element = _localPrefixedLookup(prefix, name);
+    if (element != null) {
+      return element;
+    }
+    element = _lookupInImportedNamespaces(identifier.identifier,
+        (Namespace namespace) => namespace.getPrefixed(prefix, name));
+    if (element != null) {
+      _definePrefixedNameWithoutChecking(prefix, name, element);
+    }
+    return element;
+  }
+
+  /**
+   * Return the element with which the given [prefix] and [name] are associated,
+   * or `null` if the name is not defined within this scope.
+   */
+  Element _localPrefixedLookup(String prefix, String name) {
+    if (_definedPrefixedNames != null) {
+      Map<String, Element> unprefixedNames = _definedPrefixedNames[prefix];
+      if (unprefixedNames != null) {
+        return unprefixedNames[name];
+      }
+    }
+    return null;
+  }
+
+  Element _lookupInImportedNamespaces(
+      Identifier identifier, Element lookup(Namespace namespace)) {
+    Set<Element> sdkElements = new HashSet<Element>();
+    Set<Element> nonSdkElements = new HashSet<Element>();
+    for (int i = 0; i < _importedNamespaces.length; i++) {
+      Element element = lookup(_importedNamespaces[i]);
+      if (element != null) {
+        if (element.library.isInSdk) {
+          sdkElements.add(element);
+        } else {
+          nonSdkElements.add(element);
+        }
+      }
+    }
+    int nonSdkCount = nonSdkElements.length;
+    int sdkCount = sdkElements.length;
+    if (nonSdkCount == 0) {
+      if (sdkCount == 0) {
+        return null;
+      } else if (sdkCount == 1) {
+        return sdkElements.first;
+      }
+    }
+    if (nonSdkCount == 1) {
+      if (sdkCount > 0) {
+        identifier.setProperty(
+            conflictingSdkElements, sdkElements.toList(growable: false));
+      }
+      return nonSdkElements.first;
+    }
+    return new MultiplyDefinedElementImpl(
+        _definingLibrary.context,
+        sdkElements.toList(growable: false),
+        nonSdkElements.toList(growable: false));
+  }
+}
+
+/**
+ * A scope containing all of the names defined in a given library.
+ */
+class LibraryScope extends EnclosedScope {
+  /**
+   * Initialize a newly created scope representing the names defined in the
+   * [definingLibrary].
+   */
+  LibraryScope(LibraryElement definingLibrary)
+      : super(new LibraryImportScope(definingLibrary)) {
+    _defineTopLevelNames(definingLibrary);
+  }
+
+  @override
+  AnalysisError getErrorForDuplicate(Element existing, Element duplicate) {
+    if (existing is PrefixElement) {
+      // TODO(scheglov) consider providing actual 'nameOffset' from the
+      // synthetic accessor
+      int offset = duplicate.nameOffset;
+      if (duplicate is PropertyAccessorElement) {
+        PropertyAccessorElement accessor = duplicate;
+        if (accessor.isSynthetic) {
+          offset = accessor.variable.nameOffset;
+        }
+      }
+      return new AnalysisError(
+          duplicate.source,
+          offset,
+          duplicate.nameLength,
+          CompileTimeErrorCode.PREFIX_COLLIDES_WITH_TOP_LEVEL_MEMBER,
+          [existing.displayName]);
+    }
+    return super.getErrorForDuplicate(existing, duplicate);
+  }
+
+  /**
+   * Add to this scope all of the public top-level names that are defined in the
+   * given [compilationUnit].
+   */
+  void _defineLocalNames(CompilationUnitElement compilationUnit) {
+    for (PropertyAccessorElement element in compilationUnit.accessors) {
+      define(element);
+    }
+    for (ClassElement element in compilationUnit.enums) {
+      define(element);
+    }
+    for (FunctionElement element in compilationUnit.functions) {
+      define(element);
+    }
+    for (FunctionTypeAliasElement element
+        in compilationUnit.functionTypeAliases) {
+      define(element);
+    }
+    for (ClassElement element in compilationUnit.types) {
+      define(element);
+    }
+  }
+
+  /**
+   * Add to this scope all of the names that are explicitly defined in the
+   * [definingLibrary].
+   */
+  void _defineTopLevelNames(LibraryElement definingLibrary) {
+    for (PrefixElement prefix in definingLibrary.prefixes) {
+      define(prefix);
+    }
+    _defineLocalNames(definingLibrary.definingCompilationUnit);
+    for (CompilationUnitElement compilationUnit in definingLibrary.parts) {
+      _defineLocalNames(compilationUnit);
+    }
+  }
+}
+
+/**
+ * A mapping of identifiers to the elements represented by those identifiers.
+ * Namespaces are the building blocks for scopes.
+ */
+class Namespace {
+  /**
+   * An empty namespace.
+   */
+  static Namespace EMPTY = new Namespace(new HashMap<String, Element>());
+
+  /**
+   * A table mapping names that are defined in this namespace to the element
+   * representing the thing declared with that name.
+   */
+  final HashMap<String, Element> _definedNames;
+
+  /**
+   * Initialize a newly created namespace to have the [_definedNames].
+   */
+  Namespace(this._definedNames);
+
+  /**
+   * Return a table containing the same mappings as those defined by this
+   * namespace.
+   */
+  Map<String, Element> get definedNames => _definedNames;
+
+  /**
+   * Return the element in this namespace that is available to the containing
+   * scope using the given name, or `null` if there is no such element.
+   */
+  Element get(String name) => _definedNames[name];
+
+  /**
+   * Return the element in this namespace whose name is the result of combining
+   * the [prefix] and the [name], separated by a period, or `null` if there is
+   * no such element.
+   */
+  Element getPrefixed(String prefix, String name) => null;
+}
+
+/**
+ * The builder used to build a namespace. Namespace builders are thread-safe and
+ * re-usable.
+ */
+class NamespaceBuilder {
+  /**
+   * Create a namespace representing the export namespace of the given [element].
+   */
+  Namespace createExportNamespaceForDirective(ExportElement element) {
+    LibraryElement exportedLibrary = element.exportedLibrary;
+    if (exportedLibrary == null) {
+      //
+      // The exported library will be null if the URI does not reference a valid
+      // library.
+      //
+      return Namespace.EMPTY;
+    }
+    HashMap<String, Element> exportedNames = _getExportMapping(exportedLibrary);
+    exportedNames = _applyCombinators(exportedNames, element.combinators);
+    return new Namespace(exportedNames);
+  }
+
+  /**
+   * Create a namespace representing the export namespace of the given [library].
+   */
+  Namespace createExportNamespaceForLibrary(LibraryElement library) {
+    HashMap<String, Element> exportedNames = _getExportMapping(library);
+    return new Namespace(exportedNames);
+  }
+
+  /**
+   * Create a namespace representing the import namespace of the given [element].
+   */
+  Namespace createImportNamespaceForDirective(ImportElement element) {
+    LibraryElement importedLibrary = element.importedLibrary;
+    if (importedLibrary == null) {
+      //
+      // The imported library will be null if the URI does not reference a valid
+      // library.
+      //
+      return Namespace.EMPTY;
+    }
+    HashMap<String, Element> exportedNames = _getExportMapping(importedLibrary);
+    exportedNames = _applyCombinators(exportedNames, element.combinators);
+    PrefixElement prefix = element.prefix;
+    if (prefix != null) {
+      return new PrefixedNamespace(prefix.name, exportedNames);
+    }
+    return new Namespace(exportedNames);
+  }
+
+  /**
+   * Create a namespace representing the public namespace of the given
+   * [library].
+   */
+  Namespace createPublicNamespaceForLibrary(LibraryElement library) {
+    HashMap<String, Element> definedNames = new HashMap<String, Element>();
+    _addPublicNames(definedNames, library.definingCompilationUnit);
+    for (CompilationUnitElement compilationUnit in library.parts) {
+      _addPublicNames(definedNames, compilationUnit);
+    }
+    return new Namespace(definedNames);
+  }
+
+  /**
+   * Add all of the names in the given [namespace] to the table of
+   * [definedNames].
+   */
+  void _addAllFromNamespace(
+      Map<String, Element> definedNames, Namespace namespace) {
+    if (namespace != null) {
+      definedNames.addAll(namespace.definedNames);
+    }
+  }
+
+  /**
+   * Add the given [element] to the table of [definedNames] if it has a
+   * publicly visible name.
+   */
+  void _addIfPublic(Map<String, Element> definedNames, Element element) {
+    String name = element.name;
+    if (name != null && !Scope.isPrivateName(name)) {
+      definedNames[name] = element;
+    }
+  }
+
+  /**
+   * Add to the table of [definedNames] all of the public top-level names that
+   * are defined in the given [compilationUnit].
+   *          namespace
+   */
+  void _addPublicNames(Map<String, Element> definedNames,
+      CompilationUnitElement compilationUnit) {
+    for (PropertyAccessorElement element in compilationUnit.accessors) {
+      _addIfPublic(definedNames, element);
+    }
+    for (ClassElement element in compilationUnit.enums) {
+      _addIfPublic(definedNames, element);
+    }
+    for (FunctionElement element in compilationUnit.functions) {
+      _addIfPublic(definedNames, element);
+    }
+    for (FunctionTypeAliasElement element
+        in compilationUnit.functionTypeAliases) {
+      _addIfPublic(definedNames, element);
+    }
+    for (ClassElement element in compilationUnit.types) {
+      _addIfPublic(definedNames, element);
+    }
+  }
+
+  /**
+   * Apply the given [combinators] to all of the names in the given table of
+   * [definedNames].
+   */
+  HashMap<String, Element> _applyCombinators(
+      HashMap<String, Element> definedNames,
+      List<NamespaceCombinator> combinators) {
+    for (NamespaceCombinator combinator in combinators) {
+      if (combinator is HideElementCombinator) {
+        definedNames = _hide(definedNames, combinator.hiddenNames);
+      } else if (combinator is ShowElementCombinator) {
+        definedNames = _show(definedNames, combinator.shownNames);
+      } else {
+        // Internal error.
+        AnalysisEngine.instance.logger
+            .logError("Unknown type of combinator: ${combinator.runtimeType}");
+      }
+    }
+    return definedNames;
+  }
+
+  /**
+   * Create a mapping table representing the export namespace of the given
+   * [library]. The set of [visitedElements] contains the libraries that do not
+   * need to be visited when processing the export directives of the given
+   * library because all of the names defined by them will be added by another
+   * library.
+   */
+  HashMap<String, Element> _computeExportMapping(
+      LibraryElement library, HashSet<LibraryElement> visitedElements) {
+    visitedElements.add(library);
+    try {
+      HashMap<String, Element> definedNames = new HashMap<String, Element>();
+      for (ExportElement element in library.exports) {
+        LibraryElement exportedLibrary = element.exportedLibrary;
+        if (exportedLibrary != null &&
+            !visitedElements.contains(exportedLibrary)) {
+          //
+          // The exported library will be null if the URI does not reference a
+          // valid library.
+          //
+          HashMap<String, Element> exportedNames =
+              _computeExportMapping(exportedLibrary, visitedElements);
+          exportedNames = _applyCombinators(exportedNames, element.combinators);
+          definedNames.addAll(exportedNames);
+        }
+      }
+      _addAllFromNamespace(
+          definedNames,
+          (library.context as InternalAnalysisContext)
+              .getPublicNamespace(library));
+      return definedNames;
+    } finally {
+      visitedElements.remove(library);
+    }
+  }
+
+  HashMap<String, Element> _getExportMapping(LibraryElement library) {
+    if (library is LibraryElementImpl) {
+      if (library.exportNamespace != null) {
+        return library.exportNamespace.definedNames;
+      } else {
+        HashMap<String, Element> exportMapping =
+            _computeExportMapping(library, new HashSet<LibraryElement>());
+        library.exportNamespace = new Namespace(exportMapping);
+        return exportMapping;
+      }
+    }
+    return _computeExportMapping(library, new HashSet<LibraryElement>());
+  }
+
+  /**
+   * Return a new map of names which has all the names from [definedNames]
+   * with exception of [hiddenNames].
+   */
+  Map<String, Element> _hide(
+      HashMap<String, Element> definedNames, List<String> hiddenNames) {
+    HashMap<String, Element> newNames =
+        new HashMap<String, Element>.from(definedNames);
+    for (String name in hiddenNames) {
+      newNames.remove(name);
+      newNames.remove("$name=");
+    }
+    return newNames;
+  }
+
+  /**
+   * Return a new map of names which has only [shownNames] from [definedNames].
+   */
+  HashMap<String, Element> _show(
+      HashMap<String, Element> definedNames, List<String> shownNames) {
+    HashMap<String, Element> newNames = new HashMap<String, Element>();
+    for (String name in shownNames) {
+      Element element = definedNames[name];
+      if (element != null) {
+        newNames[name] = element;
+      }
+      String setterName = "$name=";
+      element = definedNames[setterName];
+      if (element != null) {
+        newNames[setterName] = element;
+      }
+    }
+    return newNames;
+  }
+}
+
+/**
+ * A mapping of identifiers to the elements represented by those identifiers.
+ * Namespaces are the building blocks for scopes.
+ */
+class PrefixedNamespace implements Namespace {
+  /**
+   * The prefix that is prepended to each of the defined names.
+   */
+  final String _prefix;
+
+  /**
+   * The length of the prefix.
+   */
+  final int _length;
+
+  /**
+   * A table mapping names that are defined in this namespace to the element
+   * representing the thing declared with that name.
+   */
+  final HashMap<String, Element> _definedNames;
+
+  /**
+   * Initialize a newly created namespace to have the names resulting from
+   * prefixing each of the [_definedNames] with the given [_prefix] (and a
+   * period).
+   */
+  PrefixedNamespace(String prefix, this._definedNames)
+      : _prefix = prefix,
+        _length = prefix.length;
+
+  @override
+  Map<String, Element> get definedNames {
+    Map<String, Element> definedNames = <String, Element>{};
+    _definedNames.forEach((String name, Element element) {
+      definedNames["$_prefix.$name"] = element;
+    });
+    return definedNames;
+  }
+
+  @override
+  Element get(String name) {
+    if (name.length > _length && name.startsWith(_prefix)) {
+      if (name.codeUnitAt(_length) == '.'.codeUnitAt(0)) {
+        return _definedNames[name.substring(_length + 1)];
+      }
+    }
+    return null;
+  }
+
+  @override
+  Element getPrefixed(String prefix, String name) {
+    if (prefix == _prefix) {
+      return _definedNames[name];
+    }
+    return null;
+  }
+}
+
+/**
+ * A name scope used by the resolver to determine which names are visible at any
+ * given point in the code.
+ */
+abstract class Scope {
+  /**
+   * The prefix used to mark an identifier as being private to its library.
+   */
+  static int PRIVATE_NAME_PREFIX = 0x5F;
+
+  /**
+   * The suffix added to the declared name of a setter when looking up the
+   * setter. Used to disambiguate between a getter and a setter that have the
+   * same name.
+   */
+  static String SETTER_SUFFIX = "=";
+
+  /**
+   * The name used to look up the method used to implement the unary minus
+   * operator. Used to disambiguate between the unary and binary operators.
+   */
+  static String UNARY_MINUS = "unary-";
+
+  /**
+   * A table mapping names that are defined in this scope to the element
+   * representing the thing declared with that name.
+   */
+  HashMap<String, Element> _definedNames = null;
+
+  /**
+   * Return the scope in which this scope is lexically enclosed.
+   */
+  Scope get enclosingScope => null;
+
+  /**
+   * Add the given [element] to this scope. If there is already an element with
+   * the given name defined in this scope, then the original element will
+   * continue to be mapped to the name.
+   */
+  void define(Element element) {
+    String name = _getName(element);
+    if (name != null && !name.isEmpty) {
+      _definedNames ??= new HashMap<String, Element>();
+      _definedNames.putIfAbsent(name, () => element);
+    }
+  }
+
+  /**
+   * Add the given [element] to this scope without checking for duplication or
+   * hiding.
+   */
+  void defineNameWithoutChecking(String name, Element element) {
+    _definedNames ??= new HashMap<String, Element>();
+    _definedNames[name] = element;
+  }
+
+  /**
+   * Add the given [element] to this scope without checking for duplication or
+   * hiding.
+   */
+  void defineWithoutChecking(Element element) {
+    _definedNames ??= new HashMap<String, Element>();
+    _definedNames[_getName(element)] = element;
+  }
+
+  /**
+   * Return the error code to be used when reporting that a name being defined
+   * locally conflicts with another element of the same name in the local scope.
+   * [existing] is the first element to be declared with the conflicting name,
+   * while [duplicate] another element declared with the conflicting name.
+   */
+  AnalysisError getErrorForDuplicate(Element existing, Element duplicate) {
+    // TODO(brianwilkerson) Customize the error message based on the types of
+    // elements that share the same name.
+    // TODO(jwren) There are 4 error codes for duplicate, but only 1 is being
+    // generated.
+    Source source = duplicate.source;
+    return new AnalysisError(source, duplicate.nameOffset, duplicate.nameLength,
+        CompileTimeErrorCode.DUPLICATE_DEFINITION, [existing.displayName]);
+  }
+
+  /**
+   * Return the source that contains the given [identifier], or the source
+   * associated with this scope if the source containing the identifier could
+   * not be determined.
+   */
+  Source getSource(AstNode identifier) {
+    CompilationUnit unit =
+        identifier.getAncestor((node) => node is CompilationUnit);
+    if (unit != null) {
+      CompilationUnitElement unitElement = unit.element;
+      if (unitElement != null) {
+        return unitElement.source;
+      }
+    }
+    return null;
+  }
+
+  /**
+   * Return the element with which the given [name] is associated, or `null` if
+   * the name is not defined within this scope. The [identifier] is the
+   * identifier node to lookup element for, used to report correct kind of a
+   * problem and associate problem with. The [referencingLibrary] is the library
+   * that contains the reference to the name, used to implement library-level
+   * privacy.
+   */
+  Element internalLookup(
+      Identifier identifier, String name, LibraryElement referencingLibrary);
+
+  /**
+   * Return the element with which the given [name] is associated, or `null` if
+   * the name is not defined within this scope. This method only returns
+   * elements that are directly defined within this scope, not elements that are
+   * defined in an enclosing scope. The [referencingLibrary] is the library that
+   * contains the reference to the name, used to implement library-level privacy.
+   */
+  Element localLookup(String name, LibraryElement referencingLibrary) {
+    if (_definedNames != null) {
+      return _definedNames[name];
+    }
+    return null;
+  }
+
+  /**
+   * Return the element with which the given [identifier] is associated, or
+   * `null` if the name is not defined within this scope. The
+   * [referencingLibrary] is the library that contains the reference to the
+   * name, used to implement library-level privacy.
+   */
+  Element lookup(Identifier identifier, LibraryElement referencingLibrary) {
+    if (identifier is PrefixedIdentifier) {
+      return _internalLookupPrefixed(identifier, identifier.prefix.name,
+          identifier.identifier.name, referencingLibrary);
+    }
+    return internalLookup(identifier, identifier.name, referencingLibrary);
+  }
+
+  /**
+   * Return `true` if the fact that the given [node] is not defined should be
+   * ignored (from the perspective of error reporting). This will be the case if
+   * there is at least one import that defines the node's prefix, and if that
+   * import either has no show combinators or has a show combinator that
+   * explicitly lists the node's name.
+   */
+  bool shouldIgnoreUndefined(Identifier node) {
+    if (enclosingScope != null) {
+      return enclosingScope.shouldIgnoreUndefined(node);
+    }
+    return false;
+  }
+
+  /**
+   * Return the name that will be used to look up the given [element].
+   */
+  String _getName(Element element) {
+    if (element is MethodElement) {
+      MethodElement method = element;
+      if (method.name == "-" && method.parameters.length == 0) {
+        return UNARY_MINUS;
+      }
+    }
+    return element.name;
+  }
+
+  /**
+   * Return the element with which the given [prefix] and [name] are associated,
+   * or `null` if the name is not defined within this scope. The [identifier] is
+   * the identifier node to lookup element for, used to report correct kind of a
+   * problem and associate problem with. The [referencingLibrary] is the library
+   * that contains the reference to the name, used to implement library-level
+   * privacy.
+   */
+  Element _internalLookupPrefixed(PrefixedIdentifier identifier, String prefix,
+      String name, LibraryElement referencingLibrary);
+
+  /**
+   * Return `true` if the given [name] is a library-private name.
+   */
+  static bool isPrivateName(String name) =>
+      name != null && StringUtilities.startsWithChar(name, PRIVATE_NAME_PREFIX);
+}
+
+/**
+ * The scope defined by the type parameters in a class.
+ */
+class TypeParameterScope extends EnclosedScope {
+  /**
+   * Initialize a newly created scope, enclosed within the [enclosingScope],
+   * that defined the type parameters from the given [classElement].
+   */
+  TypeParameterScope(Scope enclosingScope, ClassElement classElement)
+      : super(enclosingScope) {
+    if (classElement == null) {
+      throw new ArgumentError("class element cannot be null");
+    }
+    _defineTypeParameters(classElement);
+  }
+
+  /**
+   * Define the type parameters declared by the [classElement].
+   */
+  void _defineTypeParameters(ClassElement classElement) {
+    for (TypeParameterElement typeParameter in classElement.typeParameters) {
+      define(typeParameter);
+    }
+  }
+}