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

// This code was auto-generated, is not intended to be edited, and is subject to
// significant change. Please see the README file for more information.
library engine.resolver;
import 'dart:collection';
import 'java_core.dart';
import 'java_engine.dart';
import 'instrumentation.dart';
import 'source.dart';
import 'error.dart';
import 'scanner.dart' as sc;
import 'utilities_general.dart';
import 'utilities_dart.dart';
import 'ast.dart';
import 'parser.dart' show Parser, ParserErrorCode;
import 'sdk.dart' show DartSdk, SdkLibrary;
import 'element.dart';
import 'html.dart' as ht;
import 'engine.dart';
import 'constant.dart';
/**
 * Instances of the class `CompilationUnitBuilder` build an element model for a single
 * compilation unit.
 *
 * @coverage dart.engine.resolver
 */
class CompilationUnitBuilder {

  /**
   * Build the compilation unit element for the given source.
   *
   * @param source the source describing the compilation unit
   * @param unit the AST structure representing the compilation unit
   * @return the compilation unit element that was built
   * @throws AnalysisException if the analysis could not be performed
   */
  CompilationUnitElementImpl buildCompilationUnit(Source source, CompilationUnit unit) {
    TimeCounter_TimeCounterHandle timeCounter = PerformanceStatistics.resolve.start();
    if (unit == null) {
      return null;
    }
    ElementHolder holder = new ElementHolder();
    ElementBuilder builder = new ElementBuilder(holder);
    unit.accept(builder);
    CompilationUnitElementImpl element = new CompilationUnitElementImpl(source.shortName);
    element.accessors = holder.accessors;
    element.functions = holder.functions;
    element.source = source;
    element.typeAliases = holder.typeAliases;
    element.types = holder.types;
    element.topLevelVariables = holder.topLevelVariables;
    unit.element = element;
    timeCounter.stop();
    return element;
  }
}
/**
 * Instances of the class `ElementBuilder` traverse an AST structure and build the element
 * model representing the AST structure.
 *
 * @coverage dart.engine.resolver
 */
class ElementBuilder extends RecursiveASTVisitor<Object> {

  /**
   * The element holder associated with the element that is currently being built.
   */
  ElementHolder _currentHolder;

  /**
   * A flag indicating whether a variable declaration is in the context of a field declaration.
   */
  bool _inFieldContext = false;

  /**
   * A flag indicating whether a variable declaration is within the body of a method or function.
   */
  bool _inFunction = false;

  /**
   * A flag indicating whether the class currently being visited can be used as a mixin.
   */
  bool _isValidMixin = false;

  /**
   * A collection holding the function types defined in a class that need to have their type
   * arguments set to the types of the type parameters for the class, or `null` if we are not
   * currently processing nodes within a class.
   */
  List<FunctionTypeImpl> _functionTypesToFix = null;

  /**
   * Initialize a newly created element builder to build the elements for a compilation unit.
   *
   * @param initialHolder the element holder associated with the compilation unit being built
   */
  ElementBuilder(ElementHolder initialHolder) {
    _currentHolder = initialHolder;
  }
  Object visitBlock(Block node) {
    bool wasInField = _inFieldContext;
    _inFieldContext = false;
    try {
      node.visitChildren(this);
    } finally {
      _inFieldContext = wasInField;
    }
    return null;
  }
  Object visitCatchClause(CatchClause node) {
    SimpleIdentifier exceptionParameter = node.exceptionParameter;
    if (exceptionParameter != null) {
      LocalVariableElementImpl exception = new LocalVariableElementImpl(exceptionParameter);
      _currentHolder.addLocalVariable(exception);
      exceptionParameter.staticElement = exception;
      SimpleIdentifier stackTraceParameter = node.stackTraceParameter;
      if (stackTraceParameter != null) {
        LocalVariableElementImpl stackTrace = new LocalVariableElementImpl(stackTraceParameter);
        _currentHolder.addLocalVariable(stackTrace);
        stackTraceParameter.staticElement = stackTrace;
      }
    }
    return super.visitCatchClause(node);
  }
  Object visitClassDeclaration(ClassDeclaration node) {
    ElementHolder holder = new ElementHolder();
    _isValidMixin = true;
    _functionTypesToFix = new List<FunctionTypeImpl>();
    visitChildren(holder, node);
    SimpleIdentifier className = node.name;
    ClassElementImpl element = new ClassElementImpl(className);
    List<TypeParameterElement> typeParameters = holder.typeParameters;
    List<Type2> typeArguments = createTypeParameterTypes(typeParameters);
    InterfaceTypeImpl interfaceType = new InterfaceTypeImpl.con1(element);
    interfaceType.typeArguments = typeArguments;
    element.type = interfaceType;
    List<ConstructorElement> constructors = holder.constructors;
    if (constructors.length == 0) {
      constructors = createDefaultConstructors(interfaceType);
    }
    element.abstract = node.abstractKeyword != null;
    element.accessors = holder.accessors;
    element.constructors = constructors;
    element.fields = holder.fields;
    element.methods = holder.methods;
    element.typeParameters = typeParameters;
    element.validMixin = _isValidMixin;
    for (FunctionTypeImpl functionType in _functionTypesToFix) {
      functionType.typeArguments = typeArguments;
    }
    _functionTypesToFix = null;
    _currentHolder.addType(element);
    className.staticElement = element;
    holder.validate();
    return null;
  }
  Object visitClassTypeAlias(ClassTypeAlias node) {
    ElementHolder holder = new ElementHolder();
    _functionTypesToFix = new List<FunctionTypeImpl>();
    visitChildren(holder, node);
    SimpleIdentifier className = node.name;
    ClassElementImpl element = new ClassElementImpl(className);
    element.abstract = node.abstractKeyword != null;
    element.typedef = true;
    List<TypeParameterElement> typeParameters = holder.typeParameters;
    element.typeParameters = typeParameters;
    List<Type2> typeArguments = createTypeParameterTypes(typeParameters);
    InterfaceTypeImpl interfaceType = new InterfaceTypeImpl.con1(element);
    interfaceType.typeArguments = typeArguments;
    element.type = interfaceType;
    element.constructors = createDefaultConstructors(interfaceType);
    for (FunctionTypeImpl functionType in _functionTypesToFix) {
      functionType.typeArguments = typeArguments;
    }
    _functionTypesToFix = null;
    _currentHolder.addType(element);
    className.staticElement = element;
    holder.validate();
    return null;
  }
  Object visitConstructorDeclaration(ConstructorDeclaration node) {
    _isValidMixin = false;
    ElementHolder holder = new ElementHolder();
    bool wasInFunction = _inFunction;
    _inFunction = true;
    try {
      visitChildren(holder, node);
    } finally {
      _inFunction = wasInFunction;
    }
    SimpleIdentifier constructorName = node.name;
    ConstructorElementImpl element = new ConstructorElementImpl(constructorName);
    if (node.factoryKeyword != null) {
      element.factory = true;
    }
    element.functions = holder.functions;
    element.labels = holder.labels;
    element.localVariables = holder.localVariables;
    element.parameters = holder.parameters;
    element.const2 = node.constKeyword != null;
    _currentHolder.addConstructor(element);
    node.element = element;
    if (constructorName == null) {
      Identifier returnType = node.returnType;
      if (returnType != null) {
        element.nameOffset = returnType.offset;
      }
    } else {
      constructorName.staticElement = element;
    }
    holder.validate();
    return null;
  }
  Object visitDeclaredIdentifier(DeclaredIdentifier node) {
    SimpleIdentifier variableName = node.identifier;
    sc.Token keyword = node.keyword;
    LocalVariableElementImpl element = new LocalVariableElementImpl(variableName);
    ForEachStatement statement = node.parent as ForEachStatement;
    int declarationEnd = node.offset + node.length;
    int statementEnd = statement.offset + statement.length;
    element.setVisibleRange(declarationEnd, statementEnd - declarationEnd - 1);
    element.const3 = matches(keyword, sc.Keyword.CONST);
    element.final2 = matches(keyword, sc.Keyword.FINAL);
    _currentHolder.addLocalVariable(element);
    variableName.staticElement = element;
    return super.visitDeclaredIdentifier(node);
  }
  Object visitDefaultFormalParameter(DefaultFormalParameter node) {
    ElementHolder holder = new ElementHolder();
    visit(holder, node.defaultValue);
    FunctionElementImpl initializer = new FunctionElementImpl();
    initializer.functions = holder.functions;
    initializer.labels = holder.labels;
    initializer.localVariables = holder.localVariables;
    initializer.parameters = holder.parameters;
    SimpleIdentifier parameterName = node.parameter.identifier;
    ParameterElementImpl parameter;
    if (node.parameter is FieldFormalParameter) {
      parameter = new DefaultFieldFormalParameterElementImpl(parameterName);
    } else {
      parameter = new DefaultParameterElementImpl(parameterName);
    }
    parameter.const3 = node.isConst;
    parameter.final2 = node.isFinal;
    parameter.initializer = initializer;
    parameter.parameterKind = node.kind;
    Expression defaultValue = node.defaultValue;
    if (defaultValue != null) {
      parameter.setDefaultValueRange(defaultValue.offset, defaultValue.length);
    }
    setParameterVisibleRange(node, parameter);
    _currentHolder.addParameter(parameter);
    parameterName.staticElement = parameter;
    node.parameter.accept(this);
    holder.validate();
    return null;
  }
  Object visitFieldDeclaration(FieldDeclaration node) {
    bool wasInField = _inFieldContext;
    _inFieldContext = true;
    try {
      node.visitChildren(this);
    } finally {
      _inFieldContext = wasInField;
    }
    return null;
  }
  Object visitFieldFormalParameter(FieldFormalParameter node) {
    if (node.parent is! DefaultFormalParameter) {
      SimpleIdentifier parameterName = node.identifier;
      FieldFormalParameterElementImpl parameter = new FieldFormalParameterElementImpl(parameterName);
      parameter.const3 = node.isConst;
      parameter.final2 = node.isFinal;
      parameter.parameterKind = node.kind;
      _currentHolder.addParameter(parameter);
      parameterName.staticElement = parameter;
    }
    ElementHolder holder = new ElementHolder();
    visitChildren(holder, node);
    ((node.element as ParameterElementImpl)).parameters = holder.parameters;
    holder.validate();
    return null;
  }
  Object visitFunctionDeclaration(FunctionDeclaration node) {
    FunctionExpression expression = node.functionExpression;
    if (expression != null) {
      ElementHolder holder = new ElementHolder();
      bool wasInFunction = _inFunction;
      _inFunction = true;
      try {
        visitChildren(holder, expression);
      } finally {
        _inFunction = wasInFunction;
      }
      sc.Token property = node.propertyKeyword;
      if (property == null) {
        SimpleIdentifier functionName = node.name;
        FunctionElementImpl element = new FunctionElementImpl.con1(functionName);
        element.functions = holder.functions;
        element.labels = holder.labels;
        element.localVariables = holder.localVariables;
        element.parameters = holder.parameters;
        if (_inFunction) {
          Block enclosingBlock = node.getAncestor(Block);
          if (enclosingBlock != null) {
            int functionEnd = node.offset + node.length;
            int blockEnd = enclosingBlock.offset + enclosingBlock.length;
            element.setVisibleRange(functionEnd, blockEnd - functionEnd - 1);
          }
        }
        _currentHolder.addFunction(element);
        expression.element = element;
        functionName.staticElement = element;
      } else {
        SimpleIdentifier propertyNameNode = node.name;
        if (propertyNameNode == null) {
          return null;
        }
        String propertyName = propertyNameNode.name;
        TopLevelVariableElementImpl variable = _currentHolder.getTopLevelVariable(propertyName) as TopLevelVariableElementImpl;
        if (variable == null) {
          variable = new TopLevelVariableElementImpl.con2(node.name.name);
          variable.final2 = true;
          variable.synthetic = true;
          _currentHolder.addTopLevelVariable(variable);
        }
        if (matches(property, sc.Keyword.GET)) {
          PropertyAccessorElementImpl getter = new PropertyAccessorElementImpl.con1(propertyNameNode);
          getter.functions = holder.functions;
          getter.labels = holder.labels;
          getter.localVariables = holder.localVariables;
          getter.variable = variable;
          getter.getter = true;
          getter.static = true;
          variable.getter = getter;
          _currentHolder.addAccessor(getter);
          expression.element = getter;
          propertyNameNode.staticElement = getter;
        } else {
          PropertyAccessorElementImpl setter = new PropertyAccessorElementImpl.con1(propertyNameNode);
          setter.functions = holder.functions;
          setter.labels = holder.labels;
          setter.localVariables = holder.localVariables;
          setter.parameters = holder.parameters;
          setter.variable = variable;
          setter.setter = true;
          setter.static = true;
          variable.setter = setter;
          variable.final2 = false;
          _currentHolder.addAccessor(setter);
          expression.element = setter;
          propertyNameNode.staticElement = setter;
        }
      }
      holder.validate();
    }
    return null;
  }
  Object visitFunctionExpression(FunctionExpression node) {
    ElementHolder holder = new ElementHolder();
    bool wasInFunction = _inFunction;
    _inFunction = true;
    try {
      visitChildren(holder, node);
    } finally {
      _inFunction = wasInFunction;
    }
    FunctionElementImpl element = new FunctionElementImpl.con2(node.beginToken.offset);
    element.functions = holder.functions;
    element.labels = holder.labels;
    element.localVariables = holder.localVariables;
    element.parameters = holder.parameters;
    if (_inFunction) {
      Block enclosingBlock = node.getAncestor(Block);
      if (enclosingBlock != null) {
        int functionEnd = node.offset + node.length;
        int blockEnd = enclosingBlock.offset + enclosingBlock.length;
        element.setVisibleRange(functionEnd, blockEnd - functionEnd - 1);
      }
    }
    FunctionTypeImpl type = new FunctionTypeImpl.con1(element);
    if (_functionTypesToFix != null) {
      _functionTypesToFix.add(type);
    }
    element.type = type;
    _currentHolder.addFunction(element);
    node.element = element;
    holder.validate();
    return null;
  }
  Object visitFunctionTypeAlias(FunctionTypeAlias node) {
    ElementHolder holder = new ElementHolder();
    visitChildren(holder, node);
    SimpleIdentifier aliasName = node.name;
    List<ParameterElement> parameters = holder.parameters;
    List<TypeParameterElement> typeParameters = holder.typeParameters;
    FunctionTypeAliasElementImpl element = new FunctionTypeAliasElementImpl(aliasName);
    element.parameters = parameters;
    element.typeParameters = typeParameters;
    FunctionTypeImpl type = new FunctionTypeImpl.con2(element);
    type.typeArguments = createTypeParameterTypes(typeParameters);
    element.type = type;
    _currentHolder.addTypeAlias(element);
    aliasName.staticElement = element;
    holder.validate();
    return null;
  }
  Object visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
    if (node.parent is! DefaultFormalParameter) {
      SimpleIdentifier parameterName = node.identifier;
      ParameterElementImpl parameter = new ParameterElementImpl.con1(parameterName);
      parameter.parameterKind = node.kind;
      setParameterVisibleRange(node, parameter);
      _currentHolder.addParameter(parameter);
      parameterName.staticElement = parameter;
    }
    ElementHolder holder = new ElementHolder();
    visitChildren(holder, node);
    ((node.element as ParameterElementImpl)).parameters = holder.parameters;
    holder.validate();
    return null;
  }
  Object visitLabeledStatement(LabeledStatement node) {
    bool onSwitchStatement = node.statement is SwitchStatement;
    for (Label label in node.labels) {
      SimpleIdentifier labelName = label.label;
      LabelElementImpl element = new LabelElementImpl(labelName, onSwitchStatement, false);
      _currentHolder.addLabel(element);
      labelName.staticElement = element;
    }
    return super.visitLabeledStatement(node);
  }
  Object visitMethodDeclaration(MethodDeclaration node) {
    ElementHolder holder = new ElementHolder();
    bool wasInFunction = _inFunction;
    _inFunction = true;
    try {
      visitChildren(holder, node);
    } finally {
      _inFunction = wasInFunction;
    }
    bool isStatic = node.isStatic;
    sc.Token property = node.propertyKeyword;
    if (property == null) {
      SimpleIdentifier methodName = node.name;
      String nameOfMethod = methodName.name;
      if (nameOfMethod == sc.TokenType.MINUS.lexeme && node.parameters.parameters.length == 0) {
        nameOfMethod = "unary-";
      }
      MethodElementImpl element = new MethodElementImpl.con2(nameOfMethod, methodName.offset);
      element.abstract = node.isAbstract;
      element.functions = holder.functions;
      element.labels = holder.labels;
      element.localVariables = holder.localVariables;
      element.parameters = holder.parameters;
      element.static = isStatic;
      _currentHolder.addMethod(element);
      methodName.staticElement = element;
    } else {
      SimpleIdentifier propertyNameNode = node.name;
      String propertyName = propertyNameNode.name;
      FieldElementImpl field = _currentHolder.getField(propertyName) as FieldElementImpl;
      if (field == null) {
        field = new FieldElementImpl.con2(node.name.name);
        field.final2 = true;
        field.static = isStatic;
        field.synthetic = true;
        _currentHolder.addField(field);
      }
      if (matches(property, sc.Keyword.GET)) {
        PropertyAccessorElementImpl getter = new PropertyAccessorElementImpl.con1(propertyNameNode);
        getter.functions = holder.functions;
        getter.labels = holder.labels;
        getter.localVariables = holder.localVariables;
        getter.variable = field;
        getter.abstract = node.body is EmptyFunctionBody && node.externalKeyword == null;
        getter.getter = true;
        getter.static = isStatic;
        field.getter = getter;
        _currentHolder.addAccessor(getter);
        propertyNameNode.staticElement = getter;
      } else {
        PropertyAccessorElementImpl setter = new PropertyAccessorElementImpl.con1(propertyNameNode);
        setter.functions = holder.functions;
        setter.labels = holder.labels;
        setter.localVariables = holder.localVariables;
        setter.parameters = holder.parameters;
        setter.variable = field;
        setter.abstract = node.body is EmptyFunctionBody && !matches(node.externalKeyword, sc.Keyword.EXTERNAL);
        setter.setter = true;
        setter.static = isStatic;
        field.setter = setter;
        field.final2 = false;
        _currentHolder.addAccessor(setter);
        propertyNameNode.staticElement = setter;
      }
    }
    holder.validate();
    return null;
  }
  Object visitSimpleFormalParameter(SimpleFormalParameter node) {
    if (node.parent is! DefaultFormalParameter) {
      SimpleIdentifier parameterName = node.identifier;
      ParameterElementImpl parameter = new ParameterElementImpl.con1(parameterName);
      parameter.const3 = node.isConst;
      parameter.final2 = node.isFinal;
      parameter.parameterKind = node.kind;
      setParameterVisibleRange(node, parameter);
      _currentHolder.addParameter(parameter);
      parameterName.staticElement = parameter;
    }
    return super.visitSimpleFormalParameter(node);
  }
  Object visitSuperExpression(SuperExpression node) {
    _isValidMixin = false;
    return super.visitSuperExpression(node);
  }
  Object visitSwitchCase(SwitchCase node) {
    for (Label label in node.labels) {
      SimpleIdentifier labelName = label.label;
      LabelElementImpl element = new LabelElementImpl(labelName, false, true);
      _currentHolder.addLabel(element);
      labelName.staticElement = element;
    }
    return super.visitSwitchCase(node);
  }
  Object visitSwitchDefault(SwitchDefault node) {
    for (Label label in node.labels) {
      SimpleIdentifier labelName = label.label;
      LabelElementImpl element = new LabelElementImpl(labelName, false, true);
      _currentHolder.addLabel(element);
      labelName.staticElement = element;
    }
    return super.visitSwitchDefault(node);
  }
  Object visitTypeParameter(TypeParameter node) {
    SimpleIdentifier parameterName = node.name;
    TypeParameterElementImpl typeParameter = new TypeParameterElementImpl(parameterName);
    TypeParameterTypeImpl typeParameterType = new TypeParameterTypeImpl(typeParameter);
    typeParameter.type = typeParameterType;
    _currentHolder.addTypeParameter(typeParameter);
    parameterName.staticElement = typeParameter;
    return super.visitTypeParameter(node);
  }
  Object visitVariableDeclaration(VariableDeclaration node) {
    sc.Token keyword = ((node.parent as VariableDeclarationList)).keyword;
    bool isConst = matches(keyword, sc.Keyword.CONST);
    bool isFinal = matches(keyword, sc.Keyword.FINAL);
    bool hasInitializer = node.initializer != null;
    VariableElementImpl element;
    if (_inFieldContext) {
      SimpleIdentifier fieldName = node.name;
      FieldElementImpl field;
      if (isConst && hasInitializer) {
        field = new ConstFieldElementImpl(fieldName);
      } else {
        field = new FieldElementImpl.con1(fieldName);
      }
      element = field;
      _currentHolder.addField(field);
      fieldName.staticElement = field;
    } else if (_inFunction) {
      SimpleIdentifier variableName = node.name;
      LocalVariableElementImpl variable;
      if (isConst && hasInitializer) {
        variable = new ConstLocalVariableElementImpl(variableName);
      } else {
        variable = new LocalVariableElementImpl(variableName);
      }
      element = variable;
      Block enclosingBlock = node.getAncestor(Block);
      int functionEnd = node.offset + node.length;
      int blockEnd = enclosingBlock.offset + enclosingBlock.length;
      variable.setVisibleRange(functionEnd, blockEnd - functionEnd - 1);
      _currentHolder.addLocalVariable(variable);
      variableName.staticElement = element;
    } else {
      SimpleIdentifier variableName = node.name;
      TopLevelVariableElementImpl variable;
      if (isConst && hasInitializer) {
        variable = new ConstTopLevelVariableElementImpl(variableName);
      } else {
        variable = new TopLevelVariableElementImpl.con1(variableName);
      }
      element = variable;
      _currentHolder.addTopLevelVariable(variable);
      variableName.staticElement = element;
    }
    element.const3 = isConst;
    element.final2 = isFinal;
    if (hasInitializer) {
      ElementHolder holder = new ElementHolder();
      bool wasInFieldContext = _inFieldContext;
      _inFieldContext = false;
      try {
        visit(holder, node.initializer);
      } finally {
        _inFieldContext = wasInFieldContext;
      }
      FunctionElementImpl initializer = new FunctionElementImpl();
      initializer.functions = holder.functions;
      initializer.labels = holder.labels;
      initializer.localVariables = holder.localVariables;
      initializer.synthetic = true;
      element.initializer = initializer;
      holder.validate();
    }
    if (element is PropertyInducingElementImpl) {
      PropertyInducingElementImpl variable = element as PropertyInducingElementImpl;
      if (_inFieldContext) {
        ((variable as FieldElementImpl)).static = matches(((node.parent.parent as FieldDeclaration)).staticKeyword, sc.Keyword.STATIC);
      }
      PropertyAccessorElementImpl getter = new PropertyAccessorElementImpl.con2(variable);
      getter.getter = true;
      getter.static = variable.isStatic;
      _currentHolder.addAccessor(getter);
      variable.getter = getter;
      if (!isFinal) {
        PropertyAccessorElementImpl setter = new PropertyAccessorElementImpl.con2(variable);
        setter.setter = true;
        setter.static = variable.isStatic;
        ParameterElementImpl parameter = new ParameterElementImpl.con2("_${variable.name}", variable.nameOffset);
        parameter.synthetic = true;
        parameter.parameterKind = ParameterKind.REQUIRED;
        setter.parameters = <ParameterElement> [parameter];
        _currentHolder.addAccessor(setter);
        variable.setter = setter;
      }
    }
    return null;
  }

  /**
   * Creates the [ConstructorElement]s array with the single default constructor element.
   *
   * @param interfaceType the interface type for which to create a default constructor
   * @return the [ConstructorElement]s array with the single default constructor element
   */
  List<ConstructorElement> createDefaultConstructors(InterfaceTypeImpl interfaceType) {
    ConstructorElementImpl constructor = new ConstructorElementImpl(null);
    constructor.synthetic = true;
    constructor.returnType = interfaceType;
    FunctionTypeImpl type = new FunctionTypeImpl.con1(constructor);
    _functionTypesToFix.add(type);
    constructor.type = type;
    return <ConstructorElement> [constructor];
  }

  /**
   * Create the types associated with the given type parameters, setting the type of each type
   * parameter, and return an array of types corresponding to the given parameters.
   *
   * @param typeParameters the type parameters for which types are to be created
   * @return an array of types corresponding to the given parameters
   */
  List<Type2> createTypeParameterTypes(List<TypeParameterElement> typeParameters) {
    int typeParameterCount = typeParameters.length;
    List<Type2> typeArguments = new List<Type2>(typeParameterCount);
    for (int i = 0; i < typeParameterCount; i++) {
      TypeParameterElementImpl typeParameter = typeParameters[i] as TypeParameterElementImpl;
      TypeParameterTypeImpl typeParameterType = new TypeParameterTypeImpl(typeParameter);
      typeParameter.type = typeParameterType;
      typeArguments[i] = typeParameterType;
    }
    return typeArguments;
  }

  /**
   * Return the body of the function that contains the given parameter, or `null` if no
   * function body could be found.
   *
   * @param node the parameter contained in the function whose body is to be returned
   * @return the body of the function that contains the given parameter
   */
  FunctionBody getFunctionBody(FormalParameter node) {
    ASTNode parent = node.parent;
    while (parent != null) {
      if (parent is ConstructorDeclaration) {
        return ((parent as ConstructorDeclaration)).body;
      } else if (parent is FunctionExpression) {
        return ((parent as FunctionExpression)).body;
      } else if (parent is MethodDeclaration) {
        return ((parent as MethodDeclaration)).body;
      }
      parent = parent.parent;
    }
    return null;
  }

  /**
   * Return `true` if the given token is a token for the given keyword.
   *
   * @param token the token being tested
   * @param keyword the keyword being tested for
   * @return `true` if the given token is a token for the given keyword
   */
  bool matches(sc.Token token, sc.Keyword keyword) => token != null && identical(token.type, sc.TokenType.KEYWORD) && identical(((token as sc.KeywordToken)).keyword, keyword);

  /**
   * Sets the visible source range for formal parameter.
   */
  void setParameterVisibleRange(FormalParameter node, ParameterElementImpl element) {
    FunctionBody body = getFunctionBody(node);
    if (body != null) {
      element.setVisibleRange(body.offset, body.length);
    }
  }

  /**
   * Make the given holder be the current holder while visiting the given node.
   *
   * @param holder the holder that will gather elements that are built while visiting the children
   * @param node the node to be visited
   */
  void visit(ElementHolder holder, ASTNode node) {
    if (node != null) {
      ElementHolder previousHolder = _currentHolder;
      _currentHolder = holder;
      try {
        node.accept(this);
      } finally {
        _currentHolder = previousHolder;
      }
    }
  }

  /**
   * Make the given holder be the current holder while visiting the children of the given node.
   *
   * @param holder the holder that will gather elements that are built while visiting the children
   * @param node the node whose children are to be visited
   */
  void visitChildren(ElementHolder holder, ASTNode node) {
    if (node != null) {
      ElementHolder previousHolder = _currentHolder;
      _currentHolder = holder;
      try {
        node.visitChildren(this);
      } finally {
        _currentHolder = previousHolder;
      }
    }
  }
}
/**
 * Instances of the class `ElementHolder` hold on to elements created while traversing an AST
 * structure so that they can be accessed when creating their enclosing element.
 *
 * @coverage dart.engine.resolver
 */
class ElementHolder {
  List<PropertyAccessorElement> _accessors;
  List<ConstructorElement> _constructors;
  List<FieldElement> _fields;
  List<FunctionElement> _functions;
  List<LabelElement> _labels;
  List<VariableElement> _localVariables;
  List<MethodElement> _methods;
  List<ParameterElement> _parameters;
  List<TopLevelVariableElement> _topLevelVariables;
  List<ClassElement> _types;
  List<FunctionTypeAliasElement> _typeAliases;
  List<TypeParameterElement> _typeParameters;
  void addAccessor(PropertyAccessorElement element) {
    if (_accessors == null) {
      _accessors = new List<PropertyAccessorElement>();
    }
    _accessors.add(element);
  }
  void addConstructor(ConstructorElement element) {
    if (_constructors == null) {
      _constructors = new List<ConstructorElement>();
    }
    _constructors.add(element);
  }
  void addField(FieldElement element) {
    if (_fields == null) {
      _fields = new List<FieldElement>();
    }
    _fields.add(element);
  }
  void addFunction(FunctionElement element) {
    if (_functions == null) {
      _functions = new List<FunctionElement>();
    }
    _functions.add(element);
  }
  void addLabel(LabelElement element) {
    if (_labels == null) {
      _labels = new List<LabelElement>();
    }
    _labels.add(element);
  }
  void addLocalVariable(LocalVariableElement element) {
    if (_localVariables == null) {
      _localVariables = new List<VariableElement>();
    }
    _localVariables.add(element);
  }
  void addMethod(MethodElement element) {
    if (_methods == null) {
      _methods = new List<MethodElement>();
    }
    _methods.add(element);
  }
  void addParameter(ParameterElement element) {
    if (_parameters == null) {
      _parameters = new List<ParameterElement>();
    }
    _parameters.add(element);
  }
  void addTopLevelVariable(TopLevelVariableElement element) {
    if (_topLevelVariables == null) {
      _topLevelVariables = new List<TopLevelVariableElement>();
    }
    _topLevelVariables.add(element);
  }
  void addType(ClassElement element) {
    if (_types == null) {
      _types = new List<ClassElement>();
    }
    _types.add(element);
  }
  void addTypeAlias(FunctionTypeAliasElement element) {
    if (_typeAliases == null) {
      _typeAliases = new List<FunctionTypeAliasElement>();
    }
    _typeAliases.add(element);
  }
  void addTypeParameter(TypeParameterElement element) {
    if (_typeParameters == null) {
      _typeParameters = new List<TypeParameterElement>();
    }
    _typeParameters.add(element);
  }
  List<PropertyAccessorElement> get accessors {
    if (_accessors == null) {
      return PropertyAccessorElementImpl.EMPTY_ARRAY;
    }
    List<PropertyAccessorElement> result = new List.from(_accessors);
    _accessors = null;
    return result;
  }
  List<ConstructorElement> get constructors {
    if (_constructors == null) {
      return ConstructorElementImpl.EMPTY_ARRAY;
    }
    List<ConstructorElement> result = new List.from(_constructors);
    _constructors = null;
    return result;
  }
  FieldElement getField(String fieldName) {
    if (_fields == null) {
      return null;
    }
    for (FieldElement field in _fields) {
      if (field.name == fieldName) {
        return field;
      }
    }
    return null;
  }
  List<FieldElement> get fields {
    if (_fields == null) {
      return FieldElementImpl.EMPTY_ARRAY;
    }
    List<FieldElement> result = new List.from(_fields);
    _fields = null;
    return result;
  }
  List<FunctionElement> get functions {
    if (_functions == null) {
      return FunctionElementImpl.EMPTY_ARRAY;
    }
    List<FunctionElement> result = new List.from(_functions);
    _functions = null;
    return result;
  }
  List<LabelElement> get labels {
    if (_labels == null) {
      return LabelElementImpl.EMPTY_ARRAY;
    }
    List<LabelElement> result = new List.from(_labels);
    _labels = null;
    return result;
  }
  List<LocalVariableElement> get localVariables {
    if (_localVariables == null) {
      return LocalVariableElementImpl.EMPTY_ARRAY;
    }
    List<LocalVariableElement> result = new List.from(_localVariables);
    _localVariables = null;
    return result;
  }
  List<MethodElement> get methods {
    if (_methods == null) {
      return MethodElementImpl.EMPTY_ARRAY;
    }
    List<MethodElement> result = new List.from(_methods);
    _methods = null;
    return result;
  }
  List<ParameterElement> get parameters {
    if (_parameters == null) {
      return ParameterElementImpl.EMPTY_ARRAY;
    }
    List<ParameterElement> result = new List.from(_parameters);
    _parameters = null;
    return result;
  }
  TopLevelVariableElement getTopLevelVariable(String variableName) {
    if (_topLevelVariables == null) {
      return null;
    }
    for (TopLevelVariableElement variable in _topLevelVariables) {
      if (variable.name == variableName) {
        return variable;
      }
    }
    return null;
  }
  List<TopLevelVariableElement> get topLevelVariables {
    if (_topLevelVariables == null) {
      return TopLevelVariableElementImpl.EMPTY_ARRAY;
    }
    List<TopLevelVariableElement> result = new List.from(_topLevelVariables);
    _topLevelVariables = null;
    return result;
  }
  List<FunctionTypeAliasElement> get typeAliases {
    if (_typeAliases == null) {
      return FunctionTypeAliasElementImpl.EMPTY_ARRAY;
    }
    List<FunctionTypeAliasElement> result = new List.from(_typeAliases);
    _typeAliases = null;
    return result;
  }
  List<TypeParameterElement> get typeParameters {
    if (_typeParameters == null) {
      return TypeParameterElementImpl.EMPTY_ARRAY;
    }
    List<TypeParameterElement> result = new List.from(_typeParameters);
    _typeParameters = null;
    return result;
  }
  List<ClassElement> get types {
    if (_types == null) {
      return ClassElementImpl.EMPTY_ARRAY;
    }
    List<ClassElement> result = new List.from(_types);
    _types = null;
    return result;
  }
  void validate() {
    JavaStringBuilder builder = new JavaStringBuilder();
    if (_accessors != null) {
      builder.append(_accessors.length);
      builder.append(" accessors");
    }
    if (_constructors != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_constructors.length);
      builder.append(" constructors");
    }
    if (_fields != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_fields.length);
      builder.append(" fields");
    }
    if (_functions != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_functions.length);
      builder.append(" functions");
    }
    if (_labels != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_labels.length);
      builder.append(" labels");
    }
    if (_localVariables != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_localVariables.length);
      builder.append(" local variables");
    }
    if (_methods != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_methods.length);
      builder.append(" methods");
    }
    if (_parameters != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_parameters.length);
      builder.append(" parameters");
    }
    if (_topLevelVariables != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_topLevelVariables.length);
      builder.append(" top-level variables");
    }
    if (_types != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_types.length);
      builder.append(" types");
    }
    if (_typeAliases != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_typeAliases.length);
      builder.append(" type aliases");
    }
    if (_typeParameters != null) {
      if (builder.length > 0) {
        builder.append("; ");
      }
      builder.append(_typeParameters.length);
      builder.append(" type parameters");
    }
    if (builder.length > 0) {
      AnalysisEngine.instance.logger.logError("Failed to capture elements: ${builder.toString()}");
    }
  }
}
/**
 * Instances of the class `HtmlUnitBuilder` build an element model for a single HTML unit.
 */
class HtmlUnitBuilder implements ht.XmlVisitor<Object> {
  static String _APPLICATION_DART_IN_DOUBLE_QUOTES = "\"application/dart\"";
  static String _APPLICATION_DART_IN_SINGLE_QUOTES = "'application/dart'";
  static String _SCRIPT = "script";
  static String _SRC = "src";
  static String _TYPE = "type";

  /**
   * The analysis context in which the element model will be built.
   */
  InternalAnalysisContext _context;

  /**
   * The error listener to which errors will be reported.
   */
  RecordingErrorListener errorListener;

  /**
   * The modification time of the source for which an element is being built.
   */
  int _modificationStamp = 0;

  /**
   * The line information associated with the source for which an element is being built, or
   * `null` if we are not building an element.
   */
  LineInfo _lineInfo;

  /**
   * The HTML element being built.
   */
  HtmlElementImpl _htmlElement;

  /**
   * The elements in the path from the HTML unit to the current tag node.
   */
  List<ht.XmlTagNode> _parentNodes;

  /**
   * The script elements being built.
   */
  List<HtmlScriptElement> _scripts;

  /**
   * A set of the libraries that were resolved while resolving the HTML unit.
   */
  final Set<Library> resolvedLibraries = new Set<Library>();

  /**
   * Initialize a newly created HTML unit builder.
   *
   * @param context the analysis context in which the element model will be built
   */
  HtmlUnitBuilder(InternalAnalysisContext context) {
    this._context = context;
    this.errorListener = new RecordingErrorListener();
  }

  /**
   * Build the HTML element for the given source.
   *
   * @param source the source describing the compilation unit
   * @return the HTML element that was built
   * @throws AnalysisException if the analysis could not be performed
   */
  HtmlElementImpl buildHtmlElement(Source source) => buildHtmlElement2(source, source.modificationStamp, _context.parseHtmlUnit(source));

  /**
   * Build the HTML element for the given source.
   *
   * @param source the source describing the compilation unit
   * @param modificationStamp the modification time of the source for which an element is being
   *          built
   * @param unit the AST structure representing the HTML
   * @throws AnalysisException if the analysis could not be performed
   */
  HtmlElementImpl buildHtmlElement2(Source source, int modificationStamp, ht.HtmlUnit unit) {
    this._modificationStamp = modificationStamp;
    _lineInfo = _context.computeLineInfo(source);
    HtmlElementImpl result = new HtmlElementImpl(_context, source.shortName);
    result.source = source;
    _htmlElement = result;
    unit.accept(this);
    _htmlElement = null;
    unit.element = result;
    return result;
  }
  Object visitHtmlUnit(ht.HtmlUnit node) {
    _parentNodes = new List<ht.XmlTagNode>();
    _scripts = new List<HtmlScriptElement>();
    try {
      node.visitChildren(this);
      _htmlElement.scripts = new List.from(_scripts);
    } finally {
      _scripts = null;
      _parentNodes = null;
    }
    return null;
  }
  Object visitXmlAttributeNode(ht.XmlAttributeNode node) => null;
  Object visitXmlTagNode(ht.XmlTagNode node) {
    if (_parentNodes.contains(node)) {
      JavaStringBuilder builder = new JavaStringBuilder();
      builder.append("Found circularity in XML nodes: ");
      bool first = true;
      for (ht.XmlTagNode pathNode in _parentNodes) {
        if (first) {
          first = false;
        } else {
          builder.append(", ");
        }
        String tagName = pathNode.tag.lexeme;
        if (identical(pathNode, node)) {
          builder.append("*");
          builder.append(tagName);
          builder.append("*");
        } else {
          builder.append(tagName);
        }
      }
      AnalysisEngine.instance.logger.logError(builder.toString());
      return null;
    }
    _parentNodes.add(node);
    try {
      if (isScriptNode(node)) {
        Source htmlSource = _htmlElement.source;
        ht.XmlAttributeNode scriptAttribute = getScriptSourcePath(node);
        String scriptSourcePath = scriptAttribute == null ? null : scriptAttribute.text;
        if (identical(node.attributeEnd.type, ht.TokenType.GT) && scriptSourcePath == null) {
          EmbeddedHtmlScriptElementImpl script = new EmbeddedHtmlScriptElementImpl(node);
          String contents = node.content;
          int attributeEnd = node.attributeEnd.end;
          LineInfo_Location location = _lineInfo.getLocation(attributeEnd);
          sc.StringScanner scanner = new sc.StringScanner(htmlSource, contents, errorListener);
          scanner.setSourceStart(location.lineNumber, location.columnNumber, attributeEnd);
          sc.Token firstToken = scanner.tokenize();
          List<int> lineStarts = scanner.lineStarts;
          Parser parser = new Parser(htmlSource, errorListener);
          CompilationUnit unit = parser.parseCompilationUnit(firstToken);
          unit.lineInfo = new LineInfo(lineStarts);
          try {
            LibraryResolver resolver = new LibraryResolver(_context);
            LibraryElementImpl library = resolver.resolveEmbeddedLibrary(htmlSource, _modificationStamp, unit, true) as LibraryElementImpl;
            script.scriptLibrary = library;
            resolvedLibraries.addAll(resolver.resolvedLibraries);
            errorListener.addAll(resolver.errorListener);
          } on AnalysisException catch (exception) {
            AnalysisEngine.instance.logger.logError3(exception);
          }
          _scripts.add(script);
        } else {
          ExternalHtmlScriptElementImpl script = new ExternalHtmlScriptElementImpl(node);
          if (scriptSourcePath != null) {
            try {
              scriptSourcePath = Uri.encodeFull(scriptSourcePath);
              parseUriWithException(scriptSourcePath);
              Source scriptSource = _context.sourceFactory.resolveUri(htmlSource, scriptSourcePath);
              script.scriptSource = scriptSource;
              if (scriptSource == null || !scriptSource.exists()) {
                reportValueError(HtmlWarningCode.URI_DOES_NOT_EXIST, scriptAttribute, [scriptSourcePath]);
              }
            } on URISyntaxException catch (exception) {
              reportValueError(HtmlWarningCode.INVALID_URI, scriptAttribute, [scriptSourcePath]);
            }
          }
          _scripts.add(script);
        }
      } else {
        node.visitChildren(this);
      }
    } finally {
      _parentNodes.remove(node);
    }
    return null;
  }

  /**
   * Return the first source attribute for the given tag node, or `null` if it does not exist.
   *
   * @param node the node containing attributes
   * @return the source attribute contained in the given tag
   */
  ht.XmlAttributeNode getScriptSourcePath(ht.XmlTagNode node) {
    for (ht.XmlAttributeNode attribute in node.attributes) {
      if (attribute.name.lexeme == _SRC) {
        return attribute;
      }
    }
    return null;
  }

  /**
   * Determine if the specified node is a Dart script.
   *
   * @param node the node to be tested (not `null`)
   * @return `true` if the node is a Dart script
   */
  bool isScriptNode(ht.XmlTagNode node) {
    if (node.tagNodes.length != 0 || node.tag.lexeme != _SCRIPT) {
      return false;
    }
    for (ht.XmlAttributeNode attribute in node.attributes) {
      if (attribute.name.lexeme == _TYPE) {
        ht.Token valueToken = attribute.value;
        if (valueToken != null) {
          String value = valueToken.lexeme;
          if (value == _APPLICATION_DART_IN_DOUBLE_QUOTES || value == _APPLICATION_DART_IN_SINGLE_QUOTES) {
            return true;
          }
        }
      }
    }
    return false;
  }

  /**
   * Report an error with the given error code at the given location. Use the given arguments to
   * compose the error message.
   *
   * @param errorCode the error code of the error to be reported
   * @param offset the offset of the first character to be highlighted
   * @param length the number of characters to be highlighted
   * @param arguments the arguments used to compose the error message
   */
  void reportError(ErrorCode errorCode, int offset, int length, List<Object> arguments) {
    errorListener.onError(new AnalysisError.con2(_htmlElement.source, offset, length, errorCode, arguments));
  }

  /**
   * Report an error with the given error code at the location of the value of the given attribute.
   * Use the given arguments to compose the error message.
   *
   * @param errorCode the error code of the error to be reported
   * @param offset the offset of the first character to be highlighted
   * @param length the number of characters to be highlighted
   * @param arguments the arguments used to compose the error message
   */
  void reportValueError(ErrorCode errorCode, ht.XmlAttributeNode attribute, List<Object> arguments) {
    int offset = attribute.value.offset + 1;
    int length = attribute.value.length - 2;
    reportError(errorCode, offset, length, arguments);
  }
}
/**
 * Instances of the class `BestPracticesVerifier` traverse an AST structure looking for
 * violations of Dart best practices.
 *
 * @coverage dart.engine.resolver
 */
class BestPracticesVerifier extends RecursiveASTVisitor<Object> {
  static String _GETTER = "getter";
  static String _HASHCODE_GETTER_NAME = "hashCode";
  static String _METHOD = "method";
  static String _NULL_TYPE_NAME = "Null";
  static String _SETTER = "setter";
  static String _TO_INT_METHOD_NAME = "toInt";

  /**
   * Given a parenthesized expression, this returns the parent (or recursively grand-parent) of the
   * expression that is a parenthesized expression, but whose parent is not a parenthesized
   * expression.
   *
   * For example given the code `(((e)))`: `(e) -> (((e)))`.
   *
   * @param parenthesizedExpression some expression whose parent is a parenthesized expression
   * @return the first parent or grand-parent that is a parenthesized expression, that does not have
   *         a parenthesized expression parent
   */
  static ParenthesizedExpression wrapParenthesizedExpression(ParenthesizedExpression parenthesizedExpression) {
    if (parenthesizedExpression.parent is ParenthesizedExpression) {
      return wrapParenthesizedExpression(parenthesizedExpression.parent as ParenthesizedExpression);
    }
    return parenthesizedExpression;
  }

  /**
   * The class containing the AST nodes being visited, or `null` if we are not in the scope of
   * a class.
   */
  ClassElement _enclosingClass;

  /**
   * The error reporter by which errors will be reported.
   */
  ErrorReporter _errorReporter;

  /**
   * Create a new instance of the [BestPracticesVerifier].
   *
   * @param errorReporter the error reporter
   */
  BestPracticesVerifier(ErrorReporter errorReporter) {
    this._errorReporter = errorReporter;
  }
  Object visitAsExpression(AsExpression node) {
    checkForUnnecessaryCast(node);
    return super.visitAsExpression(node);
  }
  Object visitBinaryExpression(BinaryExpression node) {
    checkForDivisionOptimizationHint(node);
    return super.visitBinaryExpression(node);
  }
  Object visitClassDeclaration(ClassDeclaration node) {
    ClassElement outerClass = _enclosingClass;
    try {
      _enclosingClass = node.element;
      return super.visitClassDeclaration(node);
    } finally {
      _enclosingClass = outerClass;
    }
  }
  Object visitIsExpression(IsExpression node) {
    checkAllTypeChecks(node);
    return super.visitIsExpression(node);
  }
  Object visitMethodDeclaration(MethodDeclaration node) {
    checkForOverridingPrivateMember(node);
    return super.visitMethodDeclaration(node);
  }

  /**
   * Check for the passed is expression for the unnecessary type check hint codes as well as null
   * checks expressed using an is expression.
   *
   * @param node the is expression to check
   * @return `true` if and only if a hint code is generated on the passed node
   * @see HintCode#TYPE_CHECK_IS_NOT_NULL
   * @see HintCode#TYPE_CHECK_IS_NULL
   * @see HintCode#UNNECESSARY_TYPE_CHECK_TRUE
   * @see HintCode#UNNECESSARY_TYPE_CHECK_FALSE
   */
  bool checkAllTypeChecks(IsExpression node) {
    Expression expression = node.expression;
    TypeName typeName = node.type;
    Type2 lhsType = expression.staticType;
    Type2 rhsType = typeName.type;
    if (lhsType == null || rhsType == null) {
      return false;
    }
    String rhsNameStr = typeName.name.name;
    if ((rhsType.isDynamic && rhsNameStr == sc.Keyword.DYNAMIC.syntax)) {
      if (node.notOperator == null) {
        _errorReporter.reportError2(HintCode.UNNECESSARY_TYPE_CHECK_TRUE, node, []);
      } else {
        _errorReporter.reportError2(HintCode.UNNECESSARY_TYPE_CHECK_FALSE, node, []);
      }
      return true;
    }
    Element rhsElement = rhsType.element;
    LibraryElement libraryElement = rhsElement != null ? rhsElement.library : null;
    if (libraryElement != null && libraryElement.isDartCore) {
      if (rhsType.isObject || (expression is NullLiteral && rhsNameStr == _NULL_TYPE_NAME)) {
        if (node.notOperator == null) {
          _errorReporter.reportError2(HintCode.UNNECESSARY_TYPE_CHECK_TRUE, node, []);
        } else {
          _errorReporter.reportError2(HintCode.UNNECESSARY_TYPE_CHECK_FALSE, node, []);
        }
        return true;
      } else if (rhsNameStr == _NULL_TYPE_NAME) {
        if (node.notOperator == null) {
          _errorReporter.reportError2(HintCode.TYPE_CHECK_IS_NULL, node, []);
        } else {
          _errorReporter.reportError2(HintCode.TYPE_CHECK_IS_NOT_NULL, node, []);
        }
        return true;
      }
    }
    return false;
  }

  /**
   * Check for the passed binary expression for the [HintCode#DIVISION_OPTIMIZATION].
   *
   * @param node the binary expression to check
   * @return `true` if and only if a hint code is generated on the passed node
   * @see HintCode#DIVISION_OPTIMIZATION
   */
  bool checkForDivisionOptimizationHint(BinaryExpression node) {
    if (node.operator.type != sc.TokenType.SLASH) {
      return false;
    }
    MethodElement methodElement = node.bestElement;
    if (methodElement == null) {
      return false;
    }
    LibraryElement libraryElement = methodElement.library;
    if (libraryElement != null && !libraryElement.isDartCore) {
      return false;
    }
    if (node.parent is ParenthesizedExpression) {
      ParenthesizedExpression parenthesizedExpression = wrapParenthesizedExpression(node.parent as ParenthesizedExpression);
      if (parenthesizedExpression.parent is MethodInvocation) {
        MethodInvocation methodInvocation = parenthesizedExpression.parent as MethodInvocation;
        if (_TO_INT_METHOD_NAME == methodInvocation.methodName.name && methodInvocation.argumentList.arguments.isEmpty) {
          _errorReporter.reportError2(HintCode.DIVISION_OPTIMIZATION, methodInvocation, []);
          return true;
        }
      }
    }
    return false;
  }

  /**
   * Check for the passed class declaration for the
   * [HintCode#OVERRIDE_EQUALS_BUT_NOT_HASH_CODE] hint code.
   *
   * @param node the class declaration to check
   * @return `true` if and only if a hint code is generated on the passed node
   * @see HintCode#OVERRIDE_EQUALS_BUT_NOT_HASH_CODE
   */
  bool checkForOverrideEqualsButNotHashCode(ClassDeclaration node) {
    ClassElement classElement = node.element;
    if (classElement == null) {
      return false;
    }
    MethodElement equalsOperatorMethodElement = classElement.getMethod(sc.TokenType.EQ_EQ.lexeme);
    if (equalsOperatorMethodElement != null) {
      PropertyAccessorElement hashCodeElement = classElement.getGetter(_HASHCODE_GETTER_NAME);
      if (hashCodeElement == null) {
        _errorReporter.reportError2(HintCode.OVERRIDE_EQUALS_BUT_NOT_HASH_CODE, node.name, [classElement.displayName]);
        return true;
      }
    }
    return false;
  }

  /**
   * Check for the passed class declaration for the
   * [HintCode#OVERRIDE_EQUALS_BUT_NOT_HASH_CODE] hint code.
   *
   * @param node the class declaration to check
   * @return `true` if and only if a hint code is generated on the passed node
   * @see HintCode#OVERRIDDING_PRIVATE_MEMBER
   */
  bool checkForOverridingPrivateMember(MethodDeclaration node) {
    if (_enclosingClass == null) {
      return false;
    }
    if (!Identifier.isPrivateName(node.name.name)) {
      return false;
    }
    ExecutableElement executableElement = node.element;
    if (executableElement == null) {
      return false;
    }
    String elementName = executableElement.name;
    bool isGetterOrSetter = executableElement is PropertyAccessorElement;
    InterfaceType superType = _enclosingClass.supertype;
    if (superType == null) {
      return false;
    }
    ClassElement classElement = superType.element;
    while (classElement != null) {
      if (_enclosingClass.library != classElement.library) {
        if (isGetterOrSetter) {
          PropertyAccessorElement overriddenAccessor = null;
          List<PropertyAccessorElement> accessors = classElement.accessors;
          for (PropertyAccessorElement propertyAccessorElement in accessors) {
            if (elementName == propertyAccessorElement.name) {
              overriddenAccessor = propertyAccessorElement;
              break;
            }
          }
          if (overriddenAccessor != null) {
            String memberType = ((executableElement as PropertyAccessorElement)).isGetter ? _GETTER : _SETTER;
            _errorReporter.reportError2(HintCode.OVERRIDDING_PRIVATE_MEMBER, node.name, [
                memberType,
                executableElement.displayName,
                classElement.displayName]);
            return true;
          }
        } else {
          MethodElement overriddenMethod = classElement.getMethod(elementName);
          if (overriddenMethod != null) {
            _errorReporter.reportError2(HintCode.OVERRIDDING_PRIVATE_MEMBER, node.name, [
                _METHOD,
                executableElement.displayName,
                classElement.displayName]);
            return true;
          }
        }
      }
      superType = classElement.supertype;
      classElement = superType != null ? superType.element : null;
    }
    return false;
  }

  /**
   * Check for the passed as expression for the [HintCode#UNNECESSARY_CAST] hint code.
   *
   * @param node the as expression to check
   * @return `true` if and only if a hint code is generated on the passed node
   * @see HintCode#UNNECESSARY_CAST
   */
  bool checkForUnnecessaryCast(AsExpression node) {
    Expression expression = node.expression;
    TypeName typeName = node.type;
    Type2 lhsType = expression.staticType;
    Type2 rhsType = typeName.type;
    if (lhsType != null && rhsType != null && !lhsType.isDynamic && !rhsType.isDynamic && lhsType.isSubtypeOf(rhsType)) {
      _errorReporter.reportError2(HintCode.UNNECESSARY_CAST, node, []);
      return true;
    }
    return false;
  }
}
/**
 * Instances of the class `Dart2JSVerifier` traverse an AST structure looking for hints for
 * code that will be compiled to JS, such as [HintCode#IS_DOUBLE].
 *
 * @coverage dart.engine.resolver
 */
class Dart2JSVerifier extends RecursiveASTVisitor<Object> {

  /**
   * The error reporter by which errors will be reported.
   */
  ErrorReporter _errorReporter;

  /**
   * The name of the `double` type.
   */
  static String _DOUBLE_TYPE_NAME = "double";

  /**
   * Create a new instance of the [Dart2JSVerifier].
   *
   * @param errorReporter the error reporter
   */
  Dart2JSVerifier(ErrorReporter errorReporter) {
    this._errorReporter = errorReporter;
  }
  Object visitIsExpression(IsExpression node) {
    checkForIsDoubleHints(node);
    return super.visitIsExpression(node);
  }

  /**
   * Check for instances of `x is double`, `x is int`, `x is! double` and
   * `x is! int`.
   *
   * @param node the is expression to check
   * @return `true` if and only if a hint code is generated on the passed node
   * @see HintCode#IS_DOUBLE
   * @see HintCode#IS_INT
   * @see HintCode#IS_NOT_DOUBLE
   * @see HintCode#IS_NOT_INT
   */
  bool checkForIsDoubleHints(IsExpression node) {
    TypeName typeName = node.type;
    Type2 type = typeName.type;
    if (type != null && type.element != null) {
      Element element = type.element;
      String typeNameStr = element.name;
      LibraryElement libraryElement = element.library;
      if (typeNameStr == _DOUBLE_TYPE_NAME && libraryElement != null && libraryElement.isDartCore) {
        if (node.notOperator == null) {
          _errorReporter.reportError2(HintCode.IS_DOUBLE, node, []);
        } else {
          _errorReporter.reportError2(HintCode.IS_NOT_DOUBLE, node, []);
        }
        return true;
      }
    }
    return false;
  }
}
/**
 * Instances of the class `DeadCodeVerifier` traverse an AST structure looking for cases of
 * [HintCode#DEAD_CODE].
 *
 * @coverage dart.engine.resolver
 */
class DeadCodeVerifier extends RecursiveASTVisitor<Object> {

  /**
   * The error reporter by which errors will be reported.
   */
  ErrorReporter _errorReporter;

  /**
   * Create a new instance of the [DeadCodeVerifier].
   *
   * @param errorReporter the error reporter
   */
  DeadCodeVerifier(ErrorReporter errorReporter) {
    this._errorReporter = errorReporter;
  }
  Object visitBinaryExpression(BinaryExpression node) {
    sc.Token operator = node.operator;
    bool isAmpAmp = identical(operator.type, sc.TokenType.AMPERSAND_AMPERSAND);
    bool isBarBar = identical(operator.type, sc.TokenType.BAR_BAR);
    if (isAmpAmp || isBarBar) {
      Expression lhsCondition = node.leftOperand;
      if (!isDebugConstant(lhsCondition)) {
        ValidResult lhsResult = getConstantBooleanValue(lhsCondition);
        if (lhsResult != null) {
          if (identical(lhsResult, ValidResult.RESULT_TRUE) && isBarBar) {
            _errorReporter.reportError2(HintCode.DEAD_CODE, node.rightOperand, []);
            safelyVisit(lhsCondition);
            return null;
          } else if (identical(lhsResult, ValidResult.RESULT_FALSE) && isAmpAmp) {
            _errorReporter.reportError2(HintCode.DEAD_CODE, node.rightOperand, []);
            safelyVisit(lhsCondition);
            return null;
          }
        }
      }
    }
    return super.visitBinaryExpression(node);
  }

  /**
   * For each [Block], this method reports and error on all statements between the end of the
   * block and the first return statement (assuming there it is not at the end of the block.)
   *
   * @param node the block to evaluate
   */
  Object visitBlock(Block node) {
    NodeList<Statement> statements = node.statements;
    int size = statements.length;
    for (int i = 0; i < size; i++) {
      Statement currentStatement = statements[i];
      safelyVisit(currentStatement);
      if (currentStatement is ReturnStatement && i != size - 1) {
        Statement nextStatement = statements[i + 1];
        Statement lastStatement = statements[size - 1];
        int offset = nextStatement.offset;
        int length = lastStatement.end - offset;
        _errorReporter.reportError3(HintCode.DEAD_CODE, offset, length, []);
        return null;
      }
    }
    return null;
  }
  Object visitConditionalExpression(ConditionalExpression node) {
    Expression conditionExpression = node.condition;
    safelyVisit(conditionExpression);
    if (!isDebugConstant(conditionExpression)) {
      ValidResult result = getConstantBooleanValue(conditionExpression);
      if (result != null) {
        if (identical(result, ValidResult.RESULT_TRUE)) {
          _errorReporter.reportError2(HintCode.DEAD_CODE, node.elseExpression, []);
          safelyVisit(node.thenExpression);
          return null;
        } else {
          _errorReporter.reportError2(HintCode.DEAD_CODE, node.thenExpression, []);
          safelyVisit(node.elseExpression);
          return null;
        }
      }
    }
    return super.visitConditionalExpression(node);
  }
  Object visitIfStatement(IfStatement node) {
    Expression conditionExpression = node.condition;
    safelyVisit(conditionExpression);
    if (!isDebugConstant(conditionExpression)) {
      ValidResult result = getConstantBooleanValue(conditionExpression);
      if (result != null) {
        if (identical(result, ValidResult.RESULT_TRUE)) {
          Statement elseStatement = node.elseStatement;
          if (elseStatement != null) {
            _errorReporter.reportError2(HintCode.DEAD_CODE, elseStatement, []);
            safelyVisit(node.thenStatement);
            return null;
          }
        } else {
          _errorReporter.reportError2(HintCode.DEAD_CODE, node.thenStatement, []);
          safelyVisit(node.elseStatement);
          return null;
        }
      }
    }
    return super.visitIfStatement(node);
  }
  Object visitTryStatement(TryStatement node) {
    safelyVisit(node.body);
    safelyVisit(node.finallyBlock);
    NodeList<CatchClause> catchClauses = node.catchClauses;
    int numOfCatchClauses = catchClauses.length;
    List<Type2> visitedTypes = new List<Type2>();
    for (int i = 0; i < numOfCatchClauses; i++) {
      CatchClause catchClause = catchClauses[i];
      if (catchClause.onKeyword != null) {
        TypeName typeName = catchClause.exceptionType;
        if (typeName != null && typeName.type != null) {
          Type2 currentType = typeName.type;
          if (currentType.isObject) {
            safelyVisit(catchClause);
            if (i + 1 != numOfCatchClauses) {
              CatchClause nextCatchClause = catchClauses[i + 1];
              CatchClause lastCatchClause = catchClauses[numOfCatchClauses - 1];
              int offset = nextCatchClause.offset;
              int length = lastCatchClause.end - offset;
              _errorReporter.reportError3(HintCode.DEAD_CODE_CATCH_FOLLOWING_CATCH, offset, length, []);
              return null;
            }
          }
          for (Type2 type in visitedTypes) {
            if (currentType.isSubtypeOf(type)) {
              CatchClause lastCatchClause = catchClauses[numOfCatchClauses - 1];
              int offset = catchClause.offset;
              int length = lastCatchClause.end - offset;
              _errorReporter.reportError3(HintCode.DEAD_CODE_ON_CATCH_SUBTYPE, offset, length, [currentType.displayName, type.displayName]);
              return null;
            }
          }
          visitedTypes.add(currentType);
        }
        safelyVisit(catchClause);
      } else {
        safelyVisit(catchClause);
        if (i + 1 != numOfCatchClauses) {
          CatchClause nextCatchClause = catchClauses[i + 1];
          CatchClause lastCatchClause = catchClauses[numOfCatchClauses - 1];
          int offset = nextCatchClause.offset;
          int length = lastCatchClause.end - offset;
          _errorReporter.reportError3(HintCode.DEAD_CODE_CATCH_FOLLOWING_CATCH, offset, length, []);
          return null;
        }
      }
    }
    return null;
  }
  Object visitWhileStatement(WhileStatement node) {
    Expression conditionExpression = node.condition;
    safelyVisit(conditionExpression);
    if (!isDebugConstant(conditionExpression)) {
      ValidResult result = getConstantBooleanValue(conditionExpression);
      if (result != null) {
        if (identical(result, ValidResult.RESULT_FALSE)) {
          _errorReporter.reportError2(HintCode.DEAD_CODE, node.body, []);
          return null;
        }
      }
    }
    safelyVisit(node.body);
    return null;
  }

  /**
   * Given some [Expression], this method returns [ValidResult#RESULT_TRUE] if it is
   * `true`, [ValidResult#RESULT_FALSE] if it is `false`, or `null` if the
   * expression is not a constant boolean value.
   *
   * @param expression the expression to evaluate
   * @return [ValidResult#RESULT_TRUE] if it is `true`, [ValidResult#RESULT_FALSE]
   *         if it is `false`, or `null` if the expression is not a constant boolean
   *         value
   */
  ValidResult getConstantBooleanValue(Expression expression) {
    if (expression is BooleanLiteral) {
      if (((expression as BooleanLiteral)).value) {
        return ValidResult.RESULT_TRUE;
      } else {
        return ValidResult.RESULT_FALSE;
      }
    }
    return null;
  }

  /**
   * Return `true` if and only if the passed expression is resolved to a constant variable.
   *
   * @param expression some conditional expression
   * @return `true` if and only if the passed expression is resolved to a constant variable
   */
  bool isDebugConstant(Expression expression) {
    Element element = null;
    if (expression is Identifier) {
      Identifier identifier = expression as Identifier;
      element = identifier.staticElement;
    } else if (expression is PropertyAccess) {
      PropertyAccess propertyAccess = expression as PropertyAccess;
      element = propertyAccess.propertyName.staticElement;
    }
    if (element is PropertyAccessorElement) {
      PropertyAccessorElement pae = element as PropertyAccessorElement;
      PropertyInducingElement variable = pae.variable;
      return variable != null && variable.isConst;
    }
    return false;
  }

  /**
   * If the given node is not `null`, visit this instance of the dead code verifier.
   *
   * @param node the node to be visited
   */
  void safelyVisit(ASTNode node) {
    if (node != null) {
      node.accept(this);
    }
  }
}
/**
 * Instances of the class `HintGenerator` traverse a library's worth of dart code at a time to
 * generate hints over the set of sources.
 *
 * @see HintCode
 * @coverage dart.engine.resolver
 */
class HintGenerator {
  List<CompilationUnit> _compilationUnits;
  AnalysisContext _context;
  AnalysisErrorListener _errorListener;
  ImportsVerifier _importsVerifier;
  bool _enableDart2JSHints = false;
  HintGenerator(List<CompilationUnit> compilationUnits, AnalysisContext context, AnalysisErrorListener errorListener) {
    this._compilationUnits = compilationUnits;
    this._context = context;
    this._errorListener = errorListener;
    LibraryElement library = compilationUnits[0].element.library;
    _importsVerifier = new ImportsVerifier(library);
    _enableDart2JSHints = context.analysisOptions.dart2jsHint;
  }
  void generateForLibrary() {
    TimeCounter_TimeCounterHandle timeCounter = PerformanceStatistics.hints.start();
    for (int i = 0; i < _compilationUnits.length; i++) {
      CompilationUnitElement element = _compilationUnits[i].element;
      if (element != null) {
        if (i == 0) {
          _importsVerifier.inDefiningCompilationUnit = true;
          generateForCompilationUnit(_compilationUnits[i], element.source);
          _importsVerifier.inDefiningCompilationUnit = false;
        } else {
          generateForCompilationUnit(_compilationUnits[i], element.source);
        }
      }
    }
    ErrorReporter definingCompilationUnitErrorReporter = new ErrorReporter(_errorListener, _compilationUnits[0].element.source);
    _importsVerifier.generateDuplicateImportHints(definingCompilationUnitErrorReporter);
    _importsVerifier.generateUnusedImportHints(definingCompilationUnitErrorReporter);
    timeCounter.stop();
  }
  void generateForCompilationUnit(CompilationUnit unit, Source source) {
    ErrorReporter errorReporter = new ErrorReporter(_errorListener, source);
    _importsVerifier.visitCompilationUnit(unit);
    new DeadCodeVerifier(errorReporter).visitCompilationUnit(unit);
    if (_enableDart2JSHints) {
      new Dart2JSVerifier(errorReporter).visitCompilationUnit(unit);
    }
    new BestPracticesVerifier(errorReporter).visitCompilationUnit(unit);
  }
}
/**
 * Instances of the class `ImportsVerifier` visit all of the referenced libraries in the
 * source code verifying that all of the imports are used, otherwise a
 * [HintCode#UNUSED_IMPORT] is generated with
 * [generateUnusedImportHints].
 *
 * While this class does not yet have support for an "Organize Imports" action, this logic built up
 * in this class could be used for such an action in the future.
 *
 * @coverage dart.engine.resolver
 */
class ImportsVerifier extends RecursiveASTVisitor<Object> {

  /**
   * This is set to `true` if the current compilation unit which is being visited is the
   * defining compilation unit for the library, its value can be set with
   * [setInDefiningCompilationUnit].
   */
  bool _inDefiningCompilationUnit = false;

  /**
   * The current library.
   */
  LibraryElement _currentLibrary;

  /**
   * A list of [ImportDirective]s that the current library imports, as identifiers are visited
   * by this visitor and an import has been identified as being used by the library, the
   * [ImportDirective] is removed from this list. After all the sources in the library have
   * been evaluated, this list represents the set of unused imports.
   *
   * @see ImportsVerifier#generateUnusedImportErrors(ErrorReporter)
   */
  List<ImportDirective> _unusedImports;

  /**
   * After the list of [unusedImports] has been computed, this list is a proper subset of the
   * unused imports that are listed more than once.
   */
  List<ImportDirective> _duplicateImports;

  /**
   * This is a map between the set of [LibraryElement]s that the current library imports, and
   * a list of [ImportDirective]s that imports the library. In cases where the current library
   * imports a library with a single directive (such as `import lib1.dart;`), the library
   * element will map to a list of one [ImportDirective], which will then be removed from the
   * [unusedImports] list. In cases where the current library imports a library with multiple
   * directives (such as `import lib1.dart; import lib1.dart show C;`), the
   * [LibraryElement] will be mapped to a list of the import directives, and the namespace
   * will need to be used to compute the correct [ImportDirective] being used, see
   * [namespaceMap].
   */
  Map<LibraryElement, List<ImportDirective>> _libraryMap;

  /**
   * In cases where there is more than one import directive per library element, this mapping is
   * used to determine which of the multiple import directives are used by generating a
   * [Namespace] for each of the imports to do lookups in the same way that they are done from
   * the [ElementResolver].
   */
  Map<ImportDirective, Namespace> _namespaceMap;

  /**
   * This is a map between prefix elements and the import directive from which they are derived. In
   * cases where a type is referenced via a prefix element, the import directive can be marked as
   * used (removed from the unusedImports) by looking at the resolved `lib` in `lib.X`,
   * instead of looking at which library the `lib.X` resolves.
   */
  Map<PrefixElement, ImportDirective> _prefixElementMap;

  /**
   * Create a new instance of the [ImportsVerifier].
   *
   * @param errorReporter the error reporter
   */
  ImportsVerifier(LibraryElement library) {
    this._currentLibrary = library;
    this._unusedImports = new List<ImportDirective>();
    this._duplicateImports = new List<ImportDirective>();
    this._libraryMap = new Map<LibraryElement, List<ImportDirective>>();
    this._namespaceMap = new Map<ImportDirective, Namespace>();
    this._prefixElementMap = new Map<PrefixElement, ImportDirective>();
  }

  /**
   * Any time after the defining compilation unit has been visited by this visitor, this method can
   * be called to report an [HintCode#DUPLICATE_IMPORT] hint for each of the import directives
   * in the [duplicateImports] list.
   *
   * @param errorReporter the error reporter to report the set of [HintCode#DUPLICATE_IMPORT]
   *          hints to
   */
  void generateDuplicateImportHints(ErrorReporter errorReporter) {
    for (ImportDirective duplicateImport in _duplicateImports) {
      errorReporter.reportError2(HintCode.DUPLICATE_IMPORT, duplicateImport.uri, []);
    }
  }

  /**
   * After all of the compilation units have been visited by this visitor, this method can be called
   * to report an [HintCode#UNUSED_IMPORT] hint for each of the import directives in the
   * [unusedImports] list.
   *
   * @param errorReporter the error reporter to report the set of [HintCode#UNUSED_IMPORT]
   *          hints to
   */
  void generateUnusedImportHints(ErrorReporter errorReporter) {
    for (ImportDirective unusedImport in _unusedImports) {
      Element element = unusedImport.element;
      if (element is ImportElement) {
        ImportElement importElement = element as ImportElement;
        LibraryElement libraryElement = importElement.importedLibrary;
        if (libraryElement != null && libraryElement.isDartCore) {
          continue;
        }
      }
      errorReporter.reportError2(HintCode.UNUSED_IMPORT, unusedImport.uri, []);
    }
  }
  Object visitCompilationUnit(CompilationUnit node) {
    if (_inDefiningCompilationUnit) {
      NodeList<Directive> directives = node.directives;
      for (Directive directive in directives) {
        if (directive is ImportDirective) {
          ImportDirective importDirective = directive as ImportDirective;
          LibraryElement libraryElement = importDirective.uriElement;
          if (libraryElement != null) {
            _unusedImports.add(importDirective);
            if (importDirective.asToken != null) {
              SimpleIdentifier prefixIdentifier = importDirective.prefix;
              if (prefixIdentifier != null) {
                Element element = prefixIdentifier.staticElement;
                if (element is PrefixElement) {
                  PrefixElement prefixElementKey = element as PrefixElement;
                  _prefixElementMap[prefixElementKey] = importDirective;
                }
              }
            }
            putIntoLibraryMap(libraryElement, importDirective);
            addAdditionalLibrariesForExports(libraryElement, importDirective, new List<LibraryElement>());
          }
        }
      }
    }
    if (_unusedImports.isEmpty) {
      return null;
    }
    if (_unusedImports.length > 1) {
      List<ImportDirective> importDirectiveArray = new List.from(_unusedImports);
      importDirectiveArray.sort(ImportDirective.COMPARATOR);
      ImportDirective currentDirective = importDirectiveArray[0];
      for (int i = 1; i < importDirectiveArray.length; i++) {
        ImportDirective nextDirective = importDirectiveArray[i];
        if (ImportDirective.COMPARATOR(currentDirective, nextDirective) == 0) {
          if (currentDirective.offset < nextDirective.offset) {
            _duplicateImports.add(nextDirective);
          } else {
            _duplicateImports.add(currentDirective);
          }
        }
        currentDirective = nextDirective;
      }
    }
    return super.visitCompilationUnit(node);
  }
  Object visitExportDirective(ExportDirective node) {
    visitMetadata(node.metadata);
    return null;
  }
  Object visitImportDirective(ImportDirective node) {
    visitMetadata(node.metadata);
    return null;
  }
  Object visitLibraryDirective(LibraryDirective node) {
    visitMetadata(node.metadata);
    return null;
  }
  Object visitPrefixedIdentifier(PrefixedIdentifier node) {
    SimpleIdentifier prefixIdentifier = node.prefix;
    Element element = prefixIdentifier.staticElement;
    if (element is PrefixElement) {
      _unusedImports.remove(_prefixElementMap[element]);
      return null;
    }
    return visitIdentifier(element, prefixIdentifier.name);
  }
  Object visitSimpleIdentifier(SimpleIdentifier node) => visitIdentifier(node.staticElement, node.name);
  void set inDefiningCompilationUnit(bool inDefiningCompilationUnit) {
    this._inDefiningCompilationUnit = inDefiningCompilationUnit;
  }

  /**
   * Recursively add any exported library elements into the [libraryMap].
   */
  void addAdditionalLibrariesForExports(LibraryElement library, ImportDirective importDirective, List<LibraryElement> exportPath) {
    if (exportPath.contains(library)) {
      return;
    }
    exportPath.add(library);
    for (LibraryElement exportedLibraryElt in library.exportedLibraries) {
      putIntoLibraryMap(exportedLibraryElt, importDirective);
      addAdditionalLibrariesForExports(exportedLibraryElt, importDirective, exportPath);
    }
  }

  /**
   * Lookup and return the [Namespace] from the [namespaceMap], if the map does not
   * have the computed namespace, compute it and cache it in the map. If the import directive is not
   * resolved or is not resolvable, `null` is returned.
   *
   * @param importDirective the import directive used to compute the returned namespace
   * @return the computed or looked up [Namespace]
   */
  Namespace computeNamespace(ImportDirective importDirective) {
    Namespace namespace = _namespaceMap[importDirective];
    if (namespace == null) {
      ImportElement importElement = importDirective.element as ImportElement;
      if (importElement != null) {
        NamespaceBuilder builder = new NamespaceBuilder();
        namespace = builder.createImportNamespace(importElement);
        _namespaceMap[importDirective] = namespace;
      }
    }
    return namespace;
  }

  /**
   * The [libraryMap] is a mapping between a library elements and a list of import
   * directives, but when adding these mappings into the [libraryMap], this method can be
   * used to simply add the mapping between the library element an an import directive without
   * needing to check to see if a list needs to be created.
   */
  void putIntoLibraryMap(LibraryElement libraryElement, ImportDirective importDirective) {
    List<ImportDirective> importList = _libraryMap[libraryElement];
    if (importList == null) {
      importList = new List<ImportDirective>();
      _libraryMap[libraryElement] = importList;
    }
    importList.add(importDirective);
  }
  Object visitIdentifier(Element element, String name) {
    if (element == null) {
      return null;
    }
    if (element is MultiplyDefinedElement) {
      MultiplyDefinedElement multiplyDefinedElement = element as MultiplyDefinedElement;
      for (Element elt in multiplyDefinedElement.conflictingElements) {
        visitIdentifier(elt, name);
      }
      return null;
    } else if (element is PrefixElement) {
      _unusedImports.remove(_prefixElementMap[element]);
      return null;
    }
    LibraryElement containingLibrary = element.library;
    if (containingLibrary == null) {
      return null;
    }
    if (_currentLibrary == containingLibrary) {
      return null;
    }
    List<ImportDirective> importsFromSameLibrary = _libraryMap[containingLibrary];
    if (importsFromSameLibrary == null) {
      return null;
    }
    if (importsFromSameLibrary.length == 1) {
      ImportDirective usedImportDirective = importsFromSameLibrary[0];
      _unusedImports.remove(usedImportDirective);
    } else {
      for (ImportDirective importDirective in importsFromSameLibrary) {
        Namespace namespace = computeNamespace(importDirective);
        if (namespace != null && namespace.get(name) != null) {
          _unusedImports.remove(importDirective);
        }
      }
    }
    return null;
  }

  /**
   * Given some [NodeList] of [Annotation]s, ensure that the identifiers are visited by
   * this visitor. Specifically, this covers the cases where AST nodes don't have their identifiers
   * visited by this visitor, but still need their annotations visited.
   *
   * @param annotations the list of annotations to visit
   */
  void visitMetadata(NodeList<Annotation> annotations) {
    for (Annotation annotation in annotations) {
      Identifier name = annotation.name;
      visitIdentifier(name.staticElement, name.name);
    }
  }
}
/**
 * Instances of the class `PubVerifier` traverse an AST structure looking for deviations from
 * pub best practices.
 */
class PubVerifier extends RecursiveASTVisitor<Object> {
  static String _PUBSPEC_YAML = "pubspec.yaml";

  /**
   * The analysis context containing the sources to be analyzed
   */
  AnalysisContext _context;

  /**
   * The error reporter by which errors will be reported.
   */
  ErrorReporter _errorReporter;
  PubVerifier(AnalysisContext context, ErrorReporter errorReporter) {
    this._context = context;
    this._errorReporter = errorReporter;
  }
  Object visitImportDirective(ImportDirective directive) {
    return null;
  }

  /**
   * This verifies that the passed file import directive is not contained in a source inside a
   * package "lib" directory hierarchy referencing a source outside that package "lib" directory
   * hierarchy.
   *
   * @param uriLiteral the import URL (not `null`)
   * @param path the file path being verified (not `null`)
   * @return `true` if and only if an error code is generated on the passed node
   * @see PubSuggestionCode.FILE_IMPORT_INSIDE_LIB_REFERENCES_FILE_OUTSIDE
   */
  bool checkForFileImportInsideLibReferencesFileOutside(StringLiteral uriLiteral, String path) {
    Source source = getSource(uriLiteral);
    String fullName = getSourceFullName(source);
    if (fullName != null) {
      int pathIndex = 0;
      int fullNameIndex = fullName.length;
      while (pathIndex < path.length && JavaString.startsWithBefore(path, "../", pathIndex)) {
        fullNameIndex = JavaString.lastIndexOf(fullName, '/', fullNameIndex);
        if (fullNameIndex < 4) {
          return false;
        }
        if (JavaString.startsWithBefore(fullName, "/lib", fullNameIndex - 4)) {
          String relativePubspecPath = path.substring(0, pathIndex + 3) + _PUBSPEC_YAML;
          Source pubspecSource = _context.sourceFactory.resolveUri(source, relativePubspecPath);
          if (pubspecSource != null && pubspecSource.exists()) {
            _errorReporter.reportError2(PubSuggestionCode.FILE_IMPORT_INSIDE_LIB_REFERENCES_FILE_OUTSIDE, uriLiteral, []);
          }
          return true;
        }
        pathIndex += 3;
      }
    }
    return false;
  }

  /**
   * This verifies that the passed file import directive is not contained in a source outside a
   * package "lib" directory hierarchy referencing a source inside that package "lib" directory
   * hierarchy.
   *
   * @param uriLiteral the import URL (not `null`)
   * @param path the file path being verified (not `null`)
   * @return `true` if and only if an error code is generated on the passed node
   * @see PubSuggestionCode.FILE_IMPORT_OUTSIDE_LIB_REFERENCES_FILE_INSIDE
   */
  bool checkForFileImportOutsideLibReferencesFileInside(StringLiteral uriLiteral, String path) {
    if (path.startsWith("lib/")) {
      if (checkForFileImportOutsideLibReferencesFileInside2(uriLiteral, path, 0)) {
        return true;
      }
    }
    int pathIndex = path.indexOf("/lib/");
    while (pathIndex != -1) {
      if (checkForFileImportOutsideLibReferencesFileInside2(uriLiteral, path, pathIndex + 1)) {
        return true;
      }
      pathIndex = JavaString.indexOf(path, "/lib/", pathIndex + 4);
    }
    return false;
  }
  bool checkForFileImportOutsideLibReferencesFileInside2(StringLiteral uriLiteral, String path, int pathIndex) {
    Source source = getSource(uriLiteral);
    String relativePubspecPath = path.substring(0, pathIndex) + _PUBSPEC_YAML;
    Source pubspecSource = _context.sourceFactory.resolveUri(source, relativePubspecPath);
    if (pubspecSource == null || !pubspecSource.exists()) {
      return false;
    }
    String fullName = getSourceFullName(source);
    if (fullName != null) {
      if (!fullName.contains("/lib/")) {
        _errorReporter.reportError2(PubSuggestionCode.FILE_IMPORT_OUTSIDE_LIB_REFERENCES_FILE_INSIDE, uriLiteral, []);
        return true;
      }
    }
    return false;
  }

  /**
   * This verifies that the passed package import directive does not contain ".."
   *
   * @param uriLiteral the import URL (not `null`)
   * @param path the path to be validated (not `null`)
   * @return `true` if and only if an error code is generated on the passed node
   * @see PubSuggestionCode.PACKAGE_IMPORT_CONTAINS_DOT_DOT
   */
  bool checkForPackageImportContainsDotDot(StringLiteral uriLiteral, String path) {
    if (path.startsWith("../") || path.contains("/../")) {
      _errorReporter.reportError2(PubSuggestionCode.PACKAGE_IMPORT_CONTAINS_DOT_DOT, uriLiteral, []);
      return true;
    }
    return false;
  }

  /**
   * Answer the source associated with the compilation unit containing the given AST node.
   *
   * @param node the node (not `null`)
   * @return the source or `null` if it could not be determined
   */
  Source getSource(ASTNode node) {
    Source source = null;
    CompilationUnit unit = node.getAncestor(CompilationUnit);
    if (unit != null) {
      CompilationUnitElement element = unit.element;
      if (element != null) {
        source = element.source;
      }
    }
    return source;
  }

  /**
   * Answer the full name of the given source. The returned value will have all
   * [File#separatorChar] replace by '/'.
   *
   * @param source the source
   * @return the full name or `null` if it could not be determined
   */
  String getSourceFullName(Source source) {
    if (source != null) {
      String fullName = source.fullName;
      if (fullName != null) {
        return fullName.replaceAll(r'\', '/');
      }
    }
    return null;
  }
}
/**
 * Instances of the class `DeclarationResolver` are used to resolve declarations in an AST
 * structure to already built elements.
 */
class DeclarationResolver extends RecursiveASTVisitor<Object> {

  /**
   * The compilation unit containing the AST nodes being visited.
   */
  CompilationUnitElement _enclosingUnit;

  /**
   * 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.
   *
   * @param unit the compilation unit to be resolved
   * @param element the root of the element model used to resolve the AST nodes
   */
  void resolve(CompilationUnit unit, CompilationUnitElement element) {
    _enclosingUnit = element;
    unit.element = element;
    unit.accept(this);
  }
  Object visitCatchClause(CatchClause node) {
    SimpleIdentifier exceptionParameter = node.exceptionParameter;
    if (exceptionParameter != null) {
      List<LocalVariableElement> localVariables = _enclosingExecutable.localVariables;
      find3(localVariables, exceptionParameter);
      SimpleIdentifier stackTraceParameter = node.stackTraceParameter;
      if (stackTraceParameter != null) {
        find3(localVariables, stackTraceParameter);
      }
    }
    return super.visitCatchClause(node);
  }
  Object visitClassDeclaration(ClassDeclaration node) {
    ClassElement outerClass = _enclosingClass;
    try {
      SimpleIdentifier className = node.name;
      _enclosingClass = find3(_enclosingUnit.types, className);
      return super.visitClassDeclaration(node);
    } finally {
      _enclosingClass = outerClass;
    }
  }
  Object visitClassTypeAlias(ClassTypeAlias node) {
    ClassElement outerClass = _enclosingClass;
    try {
      SimpleIdentifier className = node.name;
      _enclosingClass = find3(_enclosingUnit.types, className);
      return super.visitClassTypeAlias(node);
    } finally {
      _enclosingClass = outerClass;
    }
  }
  Object visitConstructorDeclaration(ConstructorDeclaration node) {
    ExecutableElement outerExecutable = _enclosingExecutable;
    try {
      SimpleIdentifier constructorName = node.name;
      if (constructorName == null) {
        _enclosingExecutable = _enclosingClass.unnamedConstructor;
      } else {
        _enclosingExecutable = _enclosingClass.getNamedConstructor(constructorName.name);
        constructorName.staticElement = _enclosingExecutable;
      }
      node.element = _enclosingExecutable as ConstructorElement;
      return super.visitConstructorDeclaration(node);
    } finally {
      _enclosingExecutable = outerExecutable;
    }
  }
  Object visitDeclaredIdentifier(DeclaredIdentifier node) {
    SimpleIdentifier variableName = node.identifier;
    find3(_enclosingExecutable.localVariables, variableName);
    return super.visitDeclaredIdentifier(node);
  }
  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 {
        if (element == null) {
        } else {
          _enclosingExecutable = element.initializer;
        }
        defaultValue.accept(this);
      } finally {
        _enclosingExecutable = outerExecutable;
      }
    }
    ParameterElement outerParameter = _enclosingParameter;
    try {
      _enclosingParameter = element;
      return super.visitDefaultFormalParameter(node);
    } finally {
      _enclosingParameter = outerParameter;
    }
  }
  Object visitExportDirective(ExportDirective node) {
    String uri = getStringValue(node.uri);
    if (uri != null) {
      LibraryElement library = _enclosingUnit.library;
      ExportElement exportElement = find5(library.exports, _enclosingUnit.context.sourceFactory.resolveUri(_enclosingUnit.source, uri));
      node.element = exportElement;
    }
    return super.visitExportDirective(node);
  }
  Object visitFieldFormalParameter(FieldFormalParameter node) {
    if (node.parent is! DefaultFormalParameter) {
      SimpleIdentifier parameterName = node.identifier;
      ParameterElement element = getElementForParameter(node, parameterName);
      ParameterElement outerParameter = _enclosingParameter;
      try {
        _enclosingParameter = element;
        return super.visitFieldFormalParameter(node);
      } finally {
        _enclosingParameter = outerParameter;
      }
    } else {
      return super.visitFieldFormalParameter(node);
    }
  }
  Object visitFunctionDeclaration(FunctionDeclaration node) {
    ExecutableElement outerExecutable = _enclosingExecutable;
    try {
      SimpleIdentifier functionName = node.name;
      sc.Token property = node.propertyKeyword;
      if (property == null) {
        if (_enclosingExecutable != null) {
          _enclosingExecutable = find3(_enclosingExecutable.functions, functionName);
        } else {
          _enclosingExecutable = find3(_enclosingUnit.functions, functionName);
        }
      } else {
        PropertyAccessorElement accessor = find3(_enclosingUnit.accessors, functionName);
        if (identical(((property as sc.KeywordToken)).keyword, sc.Keyword.SET)) {
          accessor = accessor.variable.setter;
          functionName.staticElement = accessor;
        }
        _enclosingExecutable = accessor;
      }
      node.functionExpression.element = _enclosingExecutable;
      return super.visitFunctionDeclaration(node);
    } finally {
      _enclosingExecutable = outerExecutable;
    }
  }
  Object visitFunctionExpression(FunctionExpression node) {
    if (node.parent is! FunctionDeclaration) {
      FunctionElement element = find2(_enclosingExecutable.functions, node.beginToken.offset);
      node.element = element;
    }
    ExecutableElement outerExecutable = _enclosingExecutable;
    try {
      _enclosingExecutable = node.element;
      return super.visitFunctionExpression(node);
    } finally {
      _enclosingExecutable = outerExecutable;
    }
  }
  Object visitFunctionTypeAlias(FunctionTypeAlias node) {
    FunctionTypeAliasElement outerAlias = _enclosingAlias;
    try {
      SimpleIdentifier aliasName = node.name;
      _enclosingAlias = find3(_enclosingUnit.functionTypeAliases, aliasName);
      return super.visitFunctionTypeAlias(node);
    } finally {
      _enclosingAlias = outerAlias;
    }
  }
  Object visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
    if (node.parent is! DefaultFormalParameter) {
      SimpleIdentifier parameterName = node.identifier;
      ParameterElement element = getElementForParameter(node, parameterName);
      ParameterElement outerParameter = _enclosingParameter;
      try {
        _enclosingParameter = element;
        return super.visitFunctionTypedFormalParameter(node);
      } finally {
        _enclosingParameter = outerParameter;
      }
    } else {
      return super.visitFunctionTypedFormalParameter(node);
    }
  }
  Object visitImportDirective(ImportDirective node) {
    String uri = getStringValue(node.uri);
    if (uri != null) {
      LibraryElement library = _enclosingUnit.library;
      ImportElement importElement = find6(library.imports, _enclosingUnit.context.sourceFactory.resolveUri(_enclosingUnit.source, uri), node.prefix);
      node.element = importElement;
    }
    return super.visitImportDirective(node);
  }
  Object visitLabeledStatement(LabeledStatement node) {
    for (Label label in node.labels) {
      SimpleIdentifier labelName = label.label;
      find3(_enclosingExecutable.labels, labelName);
    }
    return super.visitLabeledStatement(node);
  }
  Object visitLibraryDirective(LibraryDirective node) {
    node.element = _enclosingUnit.library;
    return super.visitLibraryDirective(node);
  }
  Object visitMethodDeclaration(MethodDeclaration node) {
    ExecutableElement outerExecutable = _enclosingExecutable;
    try {
      sc.Token property = node.propertyKeyword;
      SimpleIdentifier methodName = node.name;
      String nameOfMethod = methodName.name;
      if (nameOfMethod == sc.TokenType.MINUS.lexeme && node.parameters.parameters.length == 0) {
        nameOfMethod = "unary-";
      }
      if (property == null) {
        _enclosingExecutable = find4(_enclosingClass.methods, nameOfMethod, methodName.offset);
        methodName.staticElement = _enclosingExecutable;
      } else {
        PropertyAccessorElement accessor = find3(_enclosingClass.accessors, methodName);
        if (identical(((property as sc.KeywordToken)).keyword, sc.Keyword.SET)) {
          accessor = accessor.variable.setter;
          methodName.staticElement = accessor;
        }
        _enclosingExecutable = accessor;
      }
      return super.visitMethodDeclaration(node);
    } finally {
      _enclosingExecutable = outerExecutable;
    }
  }
  Object visitPartDirective(PartDirective node) {
    String uri = getStringValue(node.uri);
    if (uri != null) {
      Source partSource = _enclosingUnit.context.sourceFactory.resolveUri(_enclosingUnit.source, uri);
      node.element = find(_enclosingUnit.library.parts, partSource);
    }
    return super.visitPartDirective(node);
  }
  Object visitPartOfDirective(PartOfDirective node) {
    node.element = _enclosingUnit.library;
    return super.visitPartOfDirective(node);
  }
  Object visitSimpleFormalParameter(SimpleFormalParameter node) {
    if (node.parent is! DefaultFormalParameter) {
      SimpleIdentifier parameterName = node.identifier;
      ParameterElement element = getElementForParameter(node, parameterName);
      ParameterElement outerParameter = _enclosingParameter;
      try {
        _enclosingParameter = element;
        return super.visitSimpleFormalParameter(node);
      } finally {
        _enclosingParameter = outerParameter;
      }
    } else {
    }
    return super.visitSimpleFormalParameter(node);
  }
  Object visitSwitchCase(SwitchCase node) {
    for (Label label in node.labels) {
      SimpleIdentifier labelName = label.label;
      find3(_enclosingExecutable.labels, labelName);
    }
    return super.visitSwitchCase(node);
  }
  Object visitSwitchDefault(SwitchDefault node) {
    for (Label label in node.labels) {
      SimpleIdentifier labelName = label.label;
      find3(_enclosingExecutable.labels, labelName);
    }
    return super.visitSwitchDefault(node);
  }
  Object visitTypeParameter(TypeParameter node) {
    SimpleIdentifier parameterName = node.name;
    if (_enclosingClass != null) {
      find3(_enclosingClass.typeParameters, parameterName);
    } else if (_enclosingAlias != null) {
      find3(_enclosingAlias.typeParameters, parameterName);
    }
    return super.visitTypeParameter(node);
  }
  Object visitVariableDeclaration(VariableDeclaration node) {
    VariableElement element = null;
    SimpleIdentifier variableName = node.name;
    if (_enclosingExecutable != null) {
      element = find3(_enclosingExecutable.localVariables, variableName);
    }
    if (element == null && _enclosingClass != null) {
      element = find3(_enclosingClass.fields, variableName);
    }
    if (element == null && _enclosingUnit != null) {
      element = find3(_enclosingUnit.topLevelVariables, variableName);
    }
    Expression initializer = node.initializer;
    if (initializer != null) {
      ExecutableElement outerExecutable = _enclosingExecutable;
      try {
        if (element == null) {
        } else {
          _enclosingExecutable = element.initializer;
        }
        return super.visitVariableDeclaration(node);
      } finally {
        _enclosingExecutable = outerExecutable;
      }
    }
    return super.visitVariableDeclaration(node);
  }

  /**
   * Return the element for the part with the given source, or `null` if there is no element
   * for the given source.
   *
   * @param parts the elements for the parts
   * @param partSource the source for the part whose element is to be returned
   * @return the element for the part with the given source
   */
  CompilationUnitElement find(List<CompilationUnitElement> parts, Source partSource) {
    for (CompilationUnitElement part in parts) {
      if (part.source == partSource) {
        return part;
      }
    }
    return null;
  }

  /**
   * Return the element in the given array of elements that was created for the declaration at the
   * given offset. This method should only be used when there is no name
   *
   * @param elements the elements of the appropriate kind that exist in the current context
   * @param offset the offset of the name of the element to be returned
   * @return the element at the given offset
   */
  Element find2(List<Element> elements, int offset) => find4(elements, "", offset);

  /**
   * Return the element in the given array of elements that was created for the declaration with the
   * given name.
   *
   * @param elements the elements of the appropriate kind that exist in the current context
   * @param identifier the name node in the declaration of the element to be returned
   * @return the element created for the declaration with the given name
   */
  Element find3(List<Element> elements, SimpleIdentifier identifier) {
    Element element = find4(elements, identifier.name, identifier.offset);
    identifier.staticElement = element;
    return element;
  }

  /**
   * Return the element in the given array of elements that was created for the declaration with the
   * given name at the given offset.
   *
   * @param elements the elements of the appropriate kind that exist in the current context
   * @param name the name of the element to be returned
   * @param offset the offset of the name of the element to be returned
   * @return the element with the given name and offset
   */
  Element find4(List<Element> elements, String name, int offset) {
    for (Element element in elements) {
      if (element.displayName == name && element.nameOffset == offset) {
        return element;
      }
    }
    return null;
  }

  /**
   * Return the export element from the given array whose library has the given source, or
   * `null` if there is no such export.
   *
   * @param exports the export elements being searched
   * @param source the source of the library associated with the export element to being searched
   *          for
   * @return the export element whose library has the given source
   */
  ExportElement find5(List<ExportElement> exports, Source source) {
    for (ExportElement export in exports) {
      if (export.exportedLibrary.source == source) {
        return export;
      }
    }
    return null;
  }

  /**
   * Return the import element from the given array whose library has the given source and that has
   * the given prefix, or `null` if there is no such import.
   *
   * @param imports the import elements being searched
   * @param source the source of the library associated with the import element to being searched
   *          for
   * @param prefix the prefix with which the library was imported
   * @return the import element whose library has the given source and prefix
   */
  ImportElement find6(List<ImportElement> imports, Source source, SimpleIdentifier prefix) {
    for (ImportElement element in imports) {
      if (element.importedLibrary.source == source) {
        PrefixElement prefixElement = element.prefix;
        if (prefix == null) {
          if (prefixElement == null) {
            return element;
          }
        } else {
          if (prefixElement != null && prefix.name == prefixElement.displayName) {
            return element;
          }
        }
      }
    }
    return null;
  }

  /**
   * Search the most closely enclosing list of parameters for a parameter with the given name.
   *
   * @param node the node defining the parameter with the given name
   * @param parameterName the name of the parameter being searched for
   * @return the element representing the parameter with that name
   */
  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;
    }
    ParameterElement element = parameters == null ? null : find3(parameters, parameterName);
    if (element == null) {
      PrintStringWriter writer = new PrintStringWriter();
      writer.println("Invalid state found in the Analysis Engine:");
      writer.println("DeclarationResolver.getElementForParameter() is visiting a parameter that does not appear to be in a method or function.");
      writer.println("Ancestors:");
      ASTNode parent = node.parent;
      while (parent != null) {
        writer.println(parent.runtimeType.toString());
        writer.println("---------");
        parent = parent.parent;
      }
      AnalysisEngine.instance.logger.logError2(writer.toString(), new AnalysisException());
    }
    return element;
  }

  /**
   * Return the value of the given string literal, or `null` if the string is not a constant
   * string without any string interpolation.
   *
   * @param literal the string literal whose value is to be returned
   * @return the value of the given string literal
   */
  String getStringValue(StringLiteral literal) {
    if (literal is StringInterpolation) {
      return null;
    }
    return literal.stringValue;
  }
}
/**
 * Instances of the class `ElementResolver` are used by instances of [ResolverVisitor]
 * to resolve references within the AST structure to the elements being referenced. The requirements
 * for the element resolver are:
 * <ol>
 * * Every [SimpleIdentifier] should be resolved to the element to which it refers.
 * Specifically:
 *
 * * An identifier within the declaration of that name should resolve to the element being
 * declared.
 * * An identifier denoting a prefix should resolve to the element representing the import that
 * defines the prefix (an [ImportElement]).
 * * An identifier denoting a variable should resolve to the element representing the variable (a
 * [VariableElement]).
 * * An identifier denoting a parameter should resolve to the element representing the parameter
 * (a [ParameterElement]).
 * * An identifier denoting a field should resolve to the element representing the getter or
 * setter being invoked (a [PropertyAccessorElement]).
 * * An identifier denoting the name of a method or function being invoked should resolve to the
 * element representing the method or function (a [ExecutableElement]).
 * * An identifier denoting a label should resolve to the element representing the label (a
 * [LabelElement]).
 *
 * The identifiers within directives are exceptions to this rule and are covered below.
 * * Every node containing a token representing an operator that can be overridden (
 * [BinaryExpression], [PrefixExpression], [PostfixExpression]) should resolve to
 * the element representing the method invoked by that operator (a [MethodElement]).
 * * Every [FunctionExpressionInvocation] should resolve to the element representing the
 * function being invoked (a [FunctionElement]). This will be the same element as that to
 * which the name is resolved if the function has a name, but is provided for those cases where an
 * unnamed function is being invoked.
 * * Every [LibraryDirective] and [PartOfDirective] should resolve to the element
 * representing the library being specified by the directive (a [LibraryElement]) unless, in
 * the case of a part-of directive, the specified library does not exist.
 * * Every [ImportDirective] and [ExportDirective] should resolve to the element
 * representing the library being specified by the directive unless the specified library does not
 * exist (an [ImportElement] or [ExportElement]).
 * * The identifier representing the prefix in an [ImportDirective] should resolve to the
 * element representing the prefix (a [PrefixElement]).
 * * The identifiers in the hide and show combinators in [ImportDirective]s and
 * [ExportDirective]s should resolve to the elements that are being hidden or shown,
 * respectively, unless those names are not defined in the specified library (or the specified
 * library does not exist).
 * * Every [PartDirective] should resolve to the element representing the compilation unit
 * being specified by the string unless the specified compilation unit does not exist (a
 * [CompilationUnitElement]).
 * </ol>
 * Note that AST nodes that would represent elements that are not defined are not resolved to
 * anything. This includes such things as references to undeclared variables (which is an error) and
 * names in hide and show combinators that are not defined in the imported library (which is not an
 * error).
 *
 * @coverage dart.engine.resolver
 */
class ElementResolver extends SimpleASTVisitor<Object> {

  /**
   * @return `true` if the given identifier is the return type of a constructor declaration.
   */
  static bool isConstructorReturnType(SimpleIdentifier node) {
<