// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

library analyzer.src.generated.ast;

import 'dart:collection';

import 'package:analyzer/dart/ast/visitor.dart';
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/src/generated/ast.dart';
import 'package:analyzer/src/generated/engine.dart' show AnalysisEngine;
import 'package:analyzer/src/generated/java_core.dart';
import 'package:analyzer/src/generated/java_engine.dart';
import 'package:analyzer/src/generated/scanner.dart';
import 'package:analyzer/src/generated/utilities_collection.dart' show TokenMap;
import 'package:analyzer/src/generated/utilities_dart.dart';

/**
 * An AST visitor that will clone any AST structure that it visits. The cloner
 * will only clone the structure, it will not preserve any resolution results or
 * properties associated with the nodes.
 */
class AstCloner implements AstVisitor<AstNode> {
  /**
   * A flag indicating whether tokens should be cloned while cloning an AST
   * structure.
   */
  final bool cloneTokens;

  /**
   * Initialize a newly created AST cloner to optionally clone tokens while
   * cloning AST nodes if [cloneTokens] is `true`.
   */
  AstCloner(
      [this.cloneTokens =
          false]); // TODO(brianwilkerson) Change this to be a named parameter.

  /**
   * Return a clone of the given [node].
   */
  AstNode cloneNode(AstNode node) {
    if (node == null) {
      return null;
    }
    return node.accept(this) as AstNode;
  }

  /**
   * Return a list containing cloned versions of the nodes in the given list of
   * [nodes].
   */
  List<AstNode> cloneNodeList(NodeList nodes) {
    int count = nodes.length;
    List clonedNodes = new List();
    for (int i = 0; i < count; i++) {
      clonedNodes.add((nodes[i]).accept(this) as AstNode);
    }
    return clonedNodes;
  }

  /**
   * Clone the given [token] if tokens are supposed to be cloned.
   */
  Token cloneToken(Token token) {
    if (cloneTokens) {
      return (token == null ? null : token.copy());
    } else {
      return token;
    }
  }

  /**
   * Clone the given [tokens] if tokens are supposed to be cloned.
   */
  List<Token> cloneTokenList(List<Token> tokens) {
    if (cloneTokens) {
      return tokens.map((Token token) => token.copy()).toList();
    }
    return tokens;
  }

  @override
  AdjacentStrings visitAdjacentStrings(AdjacentStrings node) =>
      new AdjacentStrings(cloneNodeList(node.strings));

  @override
  Annotation visitAnnotation(Annotation node) => new Annotation(
      cloneToken(node.atSign),
      cloneNode(node.name),
      cloneToken(node.period),
      cloneNode(node.constructorName),
      cloneNode(node.arguments));

  @override
  ArgumentList visitArgumentList(ArgumentList node) => new ArgumentList(
      cloneToken(node.leftParenthesis),
      cloneNodeList(node.arguments),
      cloneToken(node.rightParenthesis));

  @override
  AsExpression visitAsExpression(AsExpression node) => new AsExpression(
      cloneNode(node.expression),
      cloneToken(node.asOperator),
      cloneNode(node.type));

  @override
  AstNode visitAssertStatement(AssertStatement node) => new AssertStatement(
      cloneToken(node.assertKeyword),
      cloneToken(node.leftParenthesis),
      cloneNode(node.condition),
      cloneToken(node.comma),
      cloneNode(node.message),
      cloneToken(node.rightParenthesis),
      cloneToken(node.semicolon));

  @override
  AssignmentExpression visitAssignmentExpression(AssignmentExpression node) =>
      new AssignmentExpression(cloneNode(node.leftHandSide),
          cloneToken(node.operator), cloneNode(node.rightHandSide));

  @override
  AwaitExpression visitAwaitExpression(AwaitExpression node) =>
      new AwaitExpression(
          cloneToken(node.awaitKeyword), cloneNode(node.expression));

  @override
  BinaryExpression visitBinaryExpression(BinaryExpression node) =>
      new BinaryExpression(cloneNode(node.leftOperand),
          cloneToken(node.operator), cloneNode(node.rightOperand));

  @override
  Block visitBlock(Block node) => new Block(cloneToken(node.leftBracket),
      cloneNodeList(node.statements), cloneToken(node.rightBracket));

  @override
  BlockFunctionBody visitBlockFunctionBody(BlockFunctionBody node) =>
      new BlockFunctionBody(cloneToken(node.keyword), cloneToken(node.star),
          cloneNode(node.block));

  @override
  BooleanLiteral visitBooleanLiteral(BooleanLiteral node) =>
      new BooleanLiteral(cloneToken(node.literal), node.value);

  @override
  BreakStatement visitBreakStatement(BreakStatement node) => new BreakStatement(
      cloneToken(node.breakKeyword),
      cloneNode(node.label),
      cloneToken(node.semicolon));

  @override
  CascadeExpression visitCascadeExpression(CascadeExpression node) =>
      new CascadeExpression(
          cloneNode(node.target), cloneNodeList(node.cascadeSections));

  @override
  CatchClause visitCatchClause(CatchClause node) => new CatchClause(
      cloneToken(node.onKeyword),
      cloneNode(node.exceptionType),
      cloneToken(node.catchKeyword),
      cloneToken(node.leftParenthesis),
      cloneNode(node.exceptionParameter),
      cloneToken(node.comma),
      cloneNode(node.stackTraceParameter),
      cloneToken(node.rightParenthesis),
      cloneNode(node.body));

  @override
  ClassDeclaration visitClassDeclaration(ClassDeclaration node) {
    ClassDeclaration copy = new ClassDeclaration(
        cloneNode(node.documentationComment),
        cloneNodeList(node.metadata),
        cloneToken(node.abstractKeyword),
        cloneToken(node.classKeyword),
        cloneNode(node.name),
        cloneNode(node.typeParameters),
        cloneNode(node.extendsClause),
        cloneNode(node.withClause),
        cloneNode(node.implementsClause),
        cloneToken(node.leftBracket),
        cloneNodeList(node.members),
        cloneToken(node.rightBracket));
    copy.nativeClause = cloneNode(node.nativeClause);
    return copy;
  }

  @override
  ClassTypeAlias visitClassTypeAlias(ClassTypeAlias node) => new ClassTypeAlias(
      cloneNode(node.documentationComment),
      cloneNodeList(node.metadata),
      cloneToken(node.typedefKeyword),
      cloneNode(node.name),
      cloneNode(node.typeParameters),
      cloneToken(node.equals),
      cloneToken(node.abstractKeyword),
      cloneNode(node.superclass),
      cloneNode(node.withClause),
      cloneNode(node.implementsClause),
      cloneToken(node.semicolon));

  @override
  Comment visitComment(Comment node) {
    if (node.isDocumentation) {
      return Comment.createDocumentationCommentWithReferences(
          cloneTokenList(node.tokens), cloneNodeList(node.references));
    } else if (node.isBlock) {
      return Comment.createBlockComment(cloneTokenList(node.tokens));
    }
    return Comment.createEndOfLineComment(cloneTokenList(node.tokens));
  }

  @override
  CommentReference visitCommentReference(CommentReference node) =>
      new CommentReference(
          cloneToken(node.newKeyword), cloneNode(node.identifier));

  @override
  CompilationUnit visitCompilationUnit(CompilationUnit node) {
    CompilationUnit clone = new CompilationUnit(
        cloneToken(node.beginToken),
        cloneNode(node.scriptTag),
        cloneNodeList(node.directives),
        cloneNodeList(node.declarations),
        cloneToken(node.endToken));
    clone.lineInfo = node.lineInfo;
    return clone;
  }

  @override
  ConditionalExpression visitConditionalExpression(
          ConditionalExpression node) =>
      new ConditionalExpression(
          cloneNode(node.condition),
          cloneToken(node.question),
          cloneNode(node.thenExpression),
          cloneToken(node.colon),
          cloneNode(node.elseExpression));

  @override
  Configuration visitConfiguration(Configuration node) => new Configuration(
      cloneToken(node.ifKeyword),
      cloneToken(node.leftParenthesis),
      cloneNode(node.name),
      cloneToken(node.equalToken),
      cloneNode(node.value),
      cloneToken(node.rightParenthesis),
      cloneNode(node.libraryUri));

  @override
  ConstructorDeclaration visitConstructorDeclaration(
          ConstructorDeclaration node) =>
      new ConstructorDeclaration(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.externalKeyword),
          cloneToken(node.constKeyword),
          cloneToken(node.factoryKeyword),
          cloneNode(node.returnType),
          cloneToken(node.period),
          cloneNode(node.name),
          cloneNode(node.parameters),
          cloneToken(node.separator),
          cloneNodeList(node.initializers),
          cloneNode(node.redirectedConstructor),
          cloneNode(node.body));

  @override
  ConstructorFieldInitializer visitConstructorFieldInitializer(
          ConstructorFieldInitializer node) =>
      new ConstructorFieldInitializer(
          cloneToken(node.thisKeyword),
          cloneToken(node.period),
          cloneNode(node.fieldName),
          cloneToken(node.equals),
          cloneNode(node.expression));

  @override
  ConstructorName visitConstructorName(ConstructorName node) =>
      new ConstructorName(
          cloneNode(node.type), cloneToken(node.period), cloneNode(node.name));

  @override
  ContinueStatement visitContinueStatement(ContinueStatement node) =>
      new ContinueStatement(cloneToken(node.continueKeyword),
          cloneNode(node.label), cloneToken(node.semicolon));

  @override
  DeclaredIdentifier visitDeclaredIdentifier(DeclaredIdentifier node) =>
      new DeclaredIdentifier(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.keyword),
          cloneNode(node.type),
          cloneNode(node.identifier));

  @override
  DefaultFormalParameter visitDefaultFormalParameter(
          DefaultFormalParameter node) =>
      new DefaultFormalParameter(cloneNode(node.parameter), node.kind,
          cloneToken(node.separator), cloneNode(node.defaultValue));

  @override
  DoStatement visitDoStatement(DoStatement node) => new DoStatement(
      cloneToken(node.doKeyword),
      cloneNode(node.body),
      cloneToken(node.whileKeyword),
      cloneToken(node.leftParenthesis),
      cloneNode(node.condition),
      cloneToken(node.rightParenthesis),
      cloneToken(node.semicolon));

  @override
  DottedName visitDottedName(DottedName node) =>
      new DottedName(cloneNodeList(node.components));

  @override
  DoubleLiteral visitDoubleLiteral(DoubleLiteral node) =>
      new DoubleLiteral(cloneToken(node.literal), node.value);

  @override
  EmptyFunctionBody visitEmptyFunctionBody(EmptyFunctionBody node) =>
      new EmptyFunctionBody(cloneToken(node.semicolon));

  @override
  EmptyStatement visitEmptyStatement(EmptyStatement node) =>
      new EmptyStatement(cloneToken(node.semicolon));

  @override
  AstNode visitEnumConstantDeclaration(EnumConstantDeclaration node) =>
      new EnumConstantDeclaration(cloneNode(node.documentationComment),
          cloneNodeList(node.metadata), cloneNode(node.name));

  @override
  EnumDeclaration visitEnumDeclaration(EnumDeclaration node) =>
      new EnumDeclaration(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.enumKeyword),
          cloneNode(node.name),
          cloneToken(node.leftBracket),
          cloneNodeList(node.constants),
          cloneToken(node.rightBracket));

  @override
  ExportDirective visitExportDirective(ExportDirective node) {
    ExportDirective directive = new ExportDirective(
        cloneNode(node.documentationComment),
        cloneNodeList(node.metadata),
        cloneToken(node.keyword),
        cloneNode(node.uri),
        cloneNodeList(node.configurations),
        cloneNodeList(node.combinators),
        cloneToken(node.semicolon));
    directive.source = node.source;
    directive.uriContent = node.uriContent;
    return directive;
  }

  @override
  ExpressionFunctionBody visitExpressionFunctionBody(
          ExpressionFunctionBody node) =>
      new ExpressionFunctionBody(
          cloneToken(node.keyword),
          cloneToken(node.functionDefinition),
          cloneNode(node.expression),
          cloneToken(node.semicolon));

  @override
  ExpressionStatement visitExpressionStatement(ExpressionStatement node) =>
      new ExpressionStatement(
          cloneNode(node.expression), cloneToken(node.semicolon));

  @override
  ExtendsClause visitExtendsClause(ExtendsClause node) => new ExtendsClause(
      cloneToken(node.extendsKeyword), cloneNode(node.superclass));

  @override
  FieldDeclaration visitFieldDeclaration(FieldDeclaration node) =>
      new FieldDeclaration(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.staticKeyword),
          cloneNode(node.fields),
          cloneToken(node.semicolon));

  @override
  FieldFormalParameter visitFieldFormalParameter(FieldFormalParameter node) =>
      new FieldFormalParameter(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.keyword),
          cloneNode(node.type),
          cloneToken(node.thisKeyword),
          cloneToken(node.period),
          cloneNode(node.identifier),
          cloneNode(node.typeParameters),
          cloneNode(node.parameters));

  @override
  ForEachStatement visitForEachStatement(ForEachStatement node) {
    DeclaredIdentifier loopVariable = node.loopVariable;
    if (loopVariable == null) {
      return new ForEachStatement.withReference(
          cloneToken(node.awaitKeyword),
          cloneToken(node.forKeyword),
          cloneToken(node.leftParenthesis),
          cloneNode(node.identifier),
          cloneToken(node.inKeyword),
          cloneNode(node.iterable),
          cloneToken(node.rightParenthesis),
          cloneNode(node.body));
    }
    return new ForEachStatement.withDeclaration(
        cloneToken(node.awaitKeyword),
        cloneToken(node.forKeyword),
        cloneToken(node.leftParenthesis),
        cloneNode(loopVariable),
        cloneToken(node.inKeyword),
        cloneNode(node.iterable),
        cloneToken(node.rightParenthesis),
        cloneNode(node.body));
  }

  @override
  FormalParameterList visitFormalParameterList(FormalParameterList node) =>
      new FormalParameterList(
          cloneToken(node.leftParenthesis),
          cloneNodeList(node.parameters),
          cloneToken(node.leftDelimiter),
          cloneToken(node.rightDelimiter),
          cloneToken(node.rightParenthesis));

  @override
  ForStatement visitForStatement(ForStatement node) => new ForStatement(
      cloneToken(node.forKeyword),
      cloneToken(node.leftParenthesis),
      cloneNode(node.variables),
      cloneNode(node.initialization),
      cloneToken(node.leftSeparator),
      cloneNode(node.condition),
      cloneToken(node.rightSeparator),
      cloneNodeList(node.updaters),
      cloneToken(node.rightParenthesis),
      cloneNode(node.body));

  @override
  FunctionDeclaration visitFunctionDeclaration(FunctionDeclaration node) =>
      new FunctionDeclaration(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.externalKeyword),
          cloneNode(node.returnType),
          cloneToken(node.propertyKeyword),
          cloneNode(node.name),
          cloneNode(node.functionExpression));

  @override
  FunctionDeclarationStatement visitFunctionDeclarationStatement(
          FunctionDeclarationStatement node) =>
      new FunctionDeclarationStatement(cloneNode(node.functionDeclaration));

  @override
  FunctionExpression visitFunctionExpression(FunctionExpression node) =>
      new FunctionExpression(cloneNode(node.typeParameters),
          cloneNode(node.parameters), cloneNode(node.body));

  @override
  FunctionExpressionInvocation visitFunctionExpressionInvocation(
          FunctionExpressionInvocation node) =>
      new FunctionExpressionInvocation(cloneNode(node.function),
          cloneNode(node.typeArguments), cloneNode(node.argumentList));

  @override
  FunctionTypeAlias visitFunctionTypeAlias(FunctionTypeAlias node) =>
      new FunctionTypeAlias(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.typedefKeyword),
          cloneNode(node.returnType),
          cloneNode(node.name),
          cloneNode(node.typeParameters),
          cloneNode(node.parameters),
          cloneToken(node.semicolon));

  @override
  FunctionTypedFormalParameter visitFunctionTypedFormalParameter(
          FunctionTypedFormalParameter node) =>
      new FunctionTypedFormalParameter(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneNode(node.returnType),
          cloneNode(node.identifier),
          cloneNode(node.typeParameters),
          cloneNode(node.parameters));

  @override
  HideCombinator visitHideCombinator(HideCombinator node) => new HideCombinator(
      cloneToken(node.keyword), cloneNodeList(node.hiddenNames));

  @override
  IfStatement visitIfStatement(IfStatement node) => new IfStatement(
      cloneToken(node.ifKeyword),
      cloneToken(node.leftParenthesis),
      cloneNode(node.condition),
      cloneToken(node.rightParenthesis),
      cloneNode(node.thenStatement),
      cloneToken(node.elseKeyword),
      cloneNode(node.elseStatement));

  @override
  ImplementsClause visitImplementsClause(ImplementsClause node) =>
      new ImplementsClause(
          cloneToken(node.implementsKeyword), cloneNodeList(node.interfaces));

  @override
  ImportDirective visitImportDirective(ImportDirective node) {
    ImportDirective directive = new ImportDirective(
        cloneNode(node.documentationComment),
        cloneNodeList(node.metadata),
        cloneToken(node.keyword),
        cloneNode(node.uri),
        cloneNodeList(node.configurations),
        cloneToken(node.deferredKeyword),
        cloneToken(node.asKeyword),
        cloneNode(node.prefix),
        cloneNodeList(node.combinators),
        cloneToken(node.semicolon));
    directive.source = node.source;
    directive.uriContent = node.uriContent;
    return directive;
  }

  @override
  IndexExpression visitIndexExpression(IndexExpression node) {
    Token period = node.period;
    if (period == null) {
      return new IndexExpression.forTarget(
          cloneNode(node.target),
          cloneToken(node.leftBracket),
          cloneNode(node.index),
          cloneToken(node.rightBracket));
    } else {
      return new IndexExpression.forCascade(
          cloneToken(period),
          cloneToken(node.leftBracket),
          cloneNode(node.index),
          cloneToken(node.rightBracket));
    }
  }

  @override
  InstanceCreationExpression visitInstanceCreationExpression(
          InstanceCreationExpression node) =>
      new InstanceCreationExpression(cloneToken(node.keyword),
          cloneNode(node.constructorName), cloneNode(node.argumentList));

  @override
  IntegerLiteral visitIntegerLiteral(IntegerLiteral node) =>
      new IntegerLiteral(cloneToken(node.literal), node.value);

  @override
  InterpolationExpression visitInterpolationExpression(
          InterpolationExpression node) =>
      new InterpolationExpression(cloneToken(node.leftBracket),
          cloneNode(node.expression), cloneToken(node.rightBracket));

  @override
  InterpolationString visitInterpolationString(InterpolationString node) =>
      new InterpolationString(cloneToken(node.contents), node.value);

  @override
  IsExpression visitIsExpression(IsExpression node) => new IsExpression(
      cloneNode(node.expression),
      cloneToken(node.isOperator),
      cloneToken(node.notOperator),
      cloneNode(node.type));

  @override
  Label visitLabel(Label node) =>
      new Label(cloneNode(node.label), cloneToken(node.colon));

  @override
  LabeledStatement visitLabeledStatement(LabeledStatement node) =>
      new LabeledStatement(
          cloneNodeList(node.labels), cloneNode(node.statement));

  @override
  LibraryDirective visitLibraryDirective(LibraryDirective node) =>
      new LibraryDirective(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.libraryKeyword),
          cloneNode(node.name),
          cloneToken(node.semicolon));

  @override
  LibraryIdentifier visitLibraryIdentifier(LibraryIdentifier node) =>
      new LibraryIdentifier(cloneNodeList(node.components));

  @override
  ListLiteral visitListLiteral(ListLiteral node) => new ListLiteral(
      cloneToken(node.constKeyword),
      cloneNode(node.typeArguments),
      cloneToken(node.leftBracket),
      cloneNodeList(node.elements),
      cloneToken(node.rightBracket));

  @override
  MapLiteral visitMapLiteral(MapLiteral node) => new MapLiteral(
      cloneToken(node.constKeyword),
      cloneNode(node.typeArguments),
      cloneToken(node.leftBracket),
      cloneNodeList(node.entries),
      cloneToken(node.rightBracket));

  @override
  MapLiteralEntry visitMapLiteralEntry(MapLiteralEntry node) =>
      new MapLiteralEntry(cloneNode(node.key), cloneToken(node.separator),
          cloneNode(node.value));

  @override
  MethodDeclaration visitMethodDeclaration(MethodDeclaration node) =>
      new MethodDeclaration(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.externalKeyword),
          cloneToken(node.modifierKeyword),
          cloneNode(node.returnType),
          cloneToken(node.propertyKeyword),
          cloneToken(node.operatorKeyword),
          cloneNode(node.name),
          cloneNode(node.typeParameters),
          cloneNode(node.parameters),
          cloneNode(node.body));

  @override
  MethodInvocation visitMethodInvocation(MethodInvocation node) =>
      new MethodInvocation(
          cloneNode(node.target),
          cloneToken(node.operator),
          cloneNode(node.methodName),
          cloneNode(node.typeArguments),
          cloneNode(node.argumentList));

  @override
  NamedExpression visitNamedExpression(NamedExpression node) =>
      new NamedExpression(cloneNode(node.name), cloneNode(node.expression));

  @override
  AstNode visitNativeClause(NativeClause node) =>
      new NativeClause(cloneToken(node.nativeKeyword), cloneNode(node.name));

  @override
  NativeFunctionBody visitNativeFunctionBody(NativeFunctionBody node) =>
      new NativeFunctionBody(cloneToken(node.nativeKeyword),
          cloneNode(node.stringLiteral), cloneToken(node.semicolon));

  @override
  NullLiteral visitNullLiteral(NullLiteral node) =>
      new NullLiteral(cloneToken(node.literal));

  @override
  ParenthesizedExpression visitParenthesizedExpression(
          ParenthesizedExpression node) =>
      new ParenthesizedExpression(cloneToken(node.leftParenthesis),
          cloneNode(node.expression), cloneToken(node.rightParenthesis));

  @override
  PartDirective visitPartDirective(PartDirective node) {
    PartDirective directive = new PartDirective(
        cloneNode(node.documentationComment),
        cloneNodeList(node.metadata),
        cloneToken(node.partKeyword),
        cloneNode(node.uri),
        cloneToken(node.semicolon));
    directive.source = node.source;
    directive.uriContent = node.uriContent;
    return directive;
  }

  @override
  PartOfDirective visitPartOfDirective(PartOfDirective node) =>
      new PartOfDirective(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.partKeyword),
          cloneToken(node.ofKeyword),
          cloneNode(node.libraryName),
          cloneToken(node.semicolon));

  @override
  PostfixExpression visitPostfixExpression(PostfixExpression node) =>
      new PostfixExpression(cloneNode(node.operand), cloneToken(node.operator));

  @override
  PrefixedIdentifier visitPrefixedIdentifier(PrefixedIdentifier node) =>
      new PrefixedIdentifier(cloneNode(node.prefix), cloneToken(node.period),
          cloneNode(node.identifier));

  @override
  PrefixExpression visitPrefixExpression(PrefixExpression node) =>
      new PrefixExpression(cloneToken(node.operator), cloneNode(node.operand));

  @override
  PropertyAccess visitPropertyAccess(PropertyAccess node) => new PropertyAccess(
      cloneNode(node.target),
      cloneToken(node.operator),
      cloneNode(node.propertyName));

  @override
  RedirectingConstructorInvocation visitRedirectingConstructorInvocation(
          RedirectingConstructorInvocation node) =>
      new RedirectingConstructorInvocation(
          cloneToken(node.thisKeyword),
          cloneToken(node.period),
          cloneNode(node.constructorName),
          cloneNode(node.argumentList));

  @override
  RethrowExpression visitRethrowExpression(RethrowExpression node) =>
      new RethrowExpression(cloneToken(node.rethrowKeyword));

  @override
  ReturnStatement visitReturnStatement(ReturnStatement node) =>
      new ReturnStatement(cloneToken(node.returnKeyword),
          cloneNode(node.expression), cloneToken(node.semicolon));

  @override
  ScriptTag visitScriptTag(ScriptTag node) =>
      new ScriptTag(cloneToken(node.scriptTag));

  @override
  ShowCombinator visitShowCombinator(ShowCombinator node) => new ShowCombinator(
      cloneToken(node.keyword), cloneNodeList(node.shownNames));

  @override
  SimpleFormalParameter visitSimpleFormalParameter(
          SimpleFormalParameter node) =>
      new SimpleFormalParameter(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.keyword),
          cloneNode(node.type),
          cloneNode(node.identifier));

  @override
  SimpleIdentifier visitSimpleIdentifier(SimpleIdentifier node) =>
      new SimpleIdentifier(cloneToken(node.token));

  @override
  SimpleStringLiteral visitSimpleStringLiteral(SimpleStringLiteral node) =>
      new SimpleStringLiteral(cloneToken(node.literal), node.value);

  @override
  StringInterpolation visitStringInterpolation(StringInterpolation node) =>
      new StringInterpolation(cloneNodeList(node.elements));

  @override
  SuperConstructorInvocation visitSuperConstructorInvocation(
          SuperConstructorInvocation node) =>
      new SuperConstructorInvocation(
          cloneToken(node.superKeyword),
          cloneToken(node.period),
          cloneNode(node.constructorName),
          cloneNode(node.argumentList));

  @override
  SuperExpression visitSuperExpression(SuperExpression node) =>
      new SuperExpression(cloneToken(node.superKeyword));

  @override
  SwitchCase visitSwitchCase(SwitchCase node) => new SwitchCase(
      cloneNodeList(node.labels),
      cloneToken(node.keyword),
      cloneNode(node.expression),
      cloneToken(node.colon),
      cloneNodeList(node.statements));

  @override
  SwitchDefault visitSwitchDefault(SwitchDefault node) => new SwitchDefault(
      cloneNodeList(node.labels),
      cloneToken(node.keyword),
      cloneToken(node.colon),
      cloneNodeList(node.statements));

  @override
  SwitchStatement visitSwitchStatement(SwitchStatement node) =>
      new SwitchStatement(
          cloneToken(node.switchKeyword),
          cloneToken(node.leftParenthesis),
          cloneNode(node.expression),
          cloneToken(node.rightParenthesis),
          cloneToken(node.leftBracket),
          cloneNodeList(node.members),
          cloneToken(node.rightBracket));

  @override
  SymbolLiteral visitSymbolLiteral(SymbolLiteral node) => new SymbolLiteral(
      cloneToken(node.poundSign), cloneTokenList(node.components));

  @override
  ThisExpression visitThisExpression(ThisExpression node) =>
      new ThisExpression(cloneToken(node.thisKeyword));

  @override
  ThrowExpression visitThrowExpression(ThrowExpression node) =>
      new ThrowExpression(
          cloneToken(node.throwKeyword), cloneNode(node.expression));

  @override
  TopLevelVariableDeclaration visitTopLevelVariableDeclaration(
          TopLevelVariableDeclaration node) =>
      new TopLevelVariableDeclaration(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneNode(node.variables),
          cloneToken(node.semicolon));

  @override
  TryStatement visitTryStatement(TryStatement node) => new TryStatement(
      cloneToken(node.tryKeyword),
      cloneNode(node.body),
      cloneNodeList(node.catchClauses),
      cloneToken(node.finallyKeyword),
      cloneNode(node.finallyBlock));

  @override
  TypeArgumentList visitTypeArgumentList(TypeArgumentList node) =>
      new TypeArgumentList(cloneToken(node.leftBracket),
          cloneNodeList(node.arguments), cloneToken(node.rightBracket));

  @override
  TypeName visitTypeName(TypeName node) =>
      new TypeName(cloneNode(node.name), cloneNode(node.typeArguments));

  @override
  TypeParameter visitTypeParameter(TypeParameter node) => new TypeParameter(
      cloneNode(node.documentationComment),
      cloneNodeList(node.metadata),
      cloneNode(node.name),
      cloneToken(node.extendsKeyword),
      cloneNode(node.bound));

  @override
  TypeParameterList visitTypeParameterList(TypeParameterList node) =>
      new TypeParameterList(cloneToken(node.leftBracket),
          cloneNodeList(node.typeParameters), cloneToken(node.rightBracket));

  @override
  VariableDeclaration visitVariableDeclaration(VariableDeclaration node) =>
      new VariableDeclaration(cloneNode(node.name), cloneToken(node.equals),
          cloneNode(node.initializer));

  @override
  VariableDeclarationList visitVariableDeclarationList(
          VariableDeclarationList node) =>
      new VariableDeclarationList(
          cloneNode(node.documentationComment),
          cloneNodeList(node.metadata),
          cloneToken(node.keyword),
          cloneNode(node.type),
          cloneNodeList(node.variables));

  @override
  VariableDeclarationStatement visitVariableDeclarationStatement(
          VariableDeclarationStatement node) =>
      new VariableDeclarationStatement(
          cloneNode(node.variables), cloneToken(node.semicolon));

  @override
  WhileStatement visitWhileStatement(WhileStatement node) => new WhileStatement(
      cloneToken(node.whileKeyword),
      cloneToken(node.leftParenthesis),
      cloneNode(node.condition),
      cloneToken(node.rightParenthesis),
      cloneNode(node.body));

  @override
  WithClause visitWithClause(WithClause node) => new WithClause(
      cloneToken(node.withKeyword), cloneNodeList(node.mixinTypes));

  @override
  YieldStatement visitYieldStatement(YieldStatement node) => new YieldStatement(
      cloneToken(node.yieldKeyword),
      cloneToken(node.star),
      cloneNode(node.expression),
      cloneToken(node.semicolon));

  /**
   * Return a clone of the given [node].
   */
  static AstNode clone(AstNode node) {
    return node.accept(new AstCloner());
  }
}

/**
 * An AstVisitor that compares the structure of two AstNodes to see whether they
 * are equal.
 */
class AstComparator implements AstVisitor<bool> {
  /**
   * The AST node with which the node being visited is to be compared. This is
   * only valid at the beginning of each visit method (until [isEqualNodes] is
   * invoked).
   */
  AstNode _other;

  /**
   * Return `true` if the [first] node and the [second] node have the same
   * structure.
   *
   * *Note:* This method is only visible for testing purposes and should not be
   * used by clients.
   */
  bool isEqualNodes(AstNode first, AstNode second) {
    if (first == null) {
      return second == null;
    } else if (second == null) {
      return false;
    } else if (first.runtimeType != second.runtimeType) {
      return false;
    }
    _other = second;
    return first.accept(this);
  }

  /**
   * Return `true` if the [first] token and the [second] token have the same
   * structure.
   *
   * *Note:* This method is only visible for testing purposes and should not be
   * used by clients.
   */
  bool isEqualTokens(Token first, Token second) {
    if (first == null) {
      return second == null;
    } else if (second == null) {
      return false;
    } else if (identical(first, second)) {
      return true;
    }
    return first.offset == second.offset &&
        first.length == second.length &&
        first.lexeme == second.lexeme;
  }

  @override
  bool visitAdjacentStrings(AdjacentStrings node) {
    AdjacentStrings other = _other as AdjacentStrings;
    return _isEqualNodeLists(node.strings, other.strings);
  }

  @override
  bool visitAnnotation(Annotation node) {
    Annotation other = _other as Annotation;
    return isEqualTokens(node.atSign, other.atSign) &&
        isEqualNodes(node.name, other.name) &&
        isEqualTokens(node.period, other.period) &&
        isEqualNodes(node.constructorName, other.constructorName) &&
        isEqualNodes(node.arguments, other.arguments);
  }

  @override
  bool visitArgumentList(ArgumentList node) {
    ArgumentList other = _other as ArgumentList;
    return isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        _isEqualNodeLists(node.arguments, other.arguments) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis);
  }

  @override
  bool visitAsExpression(AsExpression node) {
    AsExpression other = _other as AsExpression;
    return isEqualNodes(node.expression, other.expression) &&
        isEqualTokens(node.asOperator, other.asOperator) &&
        isEqualNodes(node.type, other.type);
  }

  @override
  bool visitAssertStatement(AssertStatement node) {
    AssertStatement other = _other as AssertStatement;
    return isEqualTokens(node.assertKeyword, other.assertKeyword) &&
        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        isEqualNodes(node.condition, other.condition) &&
        isEqualTokens(node.comma, other.comma) &&
        isEqualNodes(node.message, other.message) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitAssignmentExpression(AssignmentExpression node) {
    AssignmentExpression other = _other as AssignmentExpression;
    return isEqualNodes(node.leftHandSide, other.leftHandSide) &&
        isEqualTokens(node.operator, other.operator) &&
        isEqualNodes(node.rightHandSide, other.rightHandSide);
  }

  @override
  bool visitAwaitExpression(AwaitExpression node) {
    AwaitExpression other = _other as AwaitExpression;
    return isEqualTokens(node.awaitKeyword, other.awaitKeyword) &&
        isEqualNodes(node.expression, other.expression);
  }

  @override
  bool visitBinaryExpression(BinaryExpression node) {
    BinaryExpression other = _other as BinaryExpression;
    return isEqualNodes(node.leftOperand, other.leftOperand) &&
        isEqualTokens(node.operator, other.operator) &&
        isEqualNodes(node.rightOperand, other.rightOperand);
  }

  @override
  bool visitBlock(Block node) {
    Block other = _other as Block;
    return isEqualTokens(node.leftBracket, other.leftBracket) &&
        _isEqualNodeLists(node.statements, other.statements) &&
        isEqualTokens(node.rightBracket, other.rightBracket);
  }

  @override
  bool visitBlockFunctionBody(BlockFunctionBody node) {
    BlockFunctionBody other = _other as BlockFunctionBody;
    return isEqualNodes(node.block, other.block);
  }

  @override
  bool visitBooleanLiteral(BooleanLiteral node) {
    BooleanLiteral other = _other as BooleanLiteral;
    return isEqualTokens(node.literal, other.literal) &&
        node.value == other.value;
  }

  @override
  bool visitBreakStatement(BreakStatement node) {
    BreakStatement other = _other as BreakStatement;
    return isEqualTokens(node.breakKeyword, other.breakKeyword) &&
        isEqualNodes(node.label, other.label) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitCascadeExpression(CascadeExpression node) {
    CascadeExpression other = _other as CascadeExpression;
    return isEqualNodes(node.target, other.target) &&
        _isEqualNodeLists(node.cascadeSections, other.cascadeSections);
  }

  @override
  bool visitCatchClause(CatchClause node) {
    CatchClause other = _other as CatchClause;
    return isEqualTokens(node.onKeyword, other.onKeyword) &&
        isEqualNodes(node.exceptionType, other.exceptionType) &&
        isEqualTokens(node.catchKeyword, other.catchKeyword) &&
        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        isEqualNodes(node.exceptionParameter, other.exceptionParameter) &&
        isEqualTokens(node.comma, other.comma) &&
        isEqualNodes(node.stackTraceParameter, other.stackTraceParameter) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
        isEqualNodes(node.body, other.body);
  }

  @override
  bool visitClassDeclaration(ClassDeclaration node) {
    ClassDeclaration other = _other as ClassDeclaration;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.abstractKeyword, other.abstractKeyword) &&
        isEqualTokens(node.classKeyword, other.classKeyword) &&
        isEqualNodes(node.name, other.name) &&
        isEqualNodes(node.typeParameters, other.typeParameters) &&
        isEqualNodes(node.extendsClause, other.extendsClause) &&
        isEqualNodes(node.withClause, other.withClause) &&
        isEqualNodes(node.implementsClause, other.implementsClause) &&
        isEqualTokens(node.leftBracket, other.leftBracket) &&
        _isEqualNodeLists(node.members, other.members) &&
        isEqualTokens(node.rightBracket, other.rightBracket);
  }

  @override
  bool visitClassTypeAlias(ClassTypeAlias node) {
    ClassTypeAlias other = _other as ClassTypeAlias;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.typedefKeyword, other.typedefKeyword) &&
        isEqualNodes(node.name, other.name) &&
        isEqualNodes(node.typeParameters, other.typeParameters) &&
        isEqualTokens(node.equals, other.equals) &&
        isEqualTokens(node.abstractKeyword, other.abstractKeyword) &&
        isEqualNodes(node.superclass, other.superclass) &&
        isEqualNodes(node.withClause, other.withClause) &&
        isEqualNodes(node.implementsClause, other.implementsClause) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitComment(Comment node) {
    Comment other = _other as Comment;
    return _isEqualNodeLists(node.references, other.references);
  }

  @override
  bool visitCommentReference(CommentReference node) {
    CommentReference other = _other as CommentReference;
    return isEqualTokens(node.newKeyword, other.newKeyword) &&
        isEqualNodes(node.identifier, other.identifier);
  }

  @override
  bool visitCompilationUnit(CompilationUnit node) {
    CompilationUnit other = _other as CompilationUnit;
    return isEqualTokens(node.beginToken, other.beginToken) &&
        isEqualNodes(node.scriptTag, other.scriptTag) &&
        _isEqualNodeLists(node.directives, other.directives) &&
        _isEqualNodeLists(node.declarations, other.declarations) &&
        isEqualTokens(node.endToken, other.endToken);
  }

  @override
  bool visitConditionalExpression(ConditionalExpression node) {
    ConditionalExpression other = _other as ConditionalExpression;
    return isEqualNodes(node.condition, other.condition) &&
        isEqualTokens(node.question, other.question) &&
        isEqualNodes(node.thenExpression, other.thenExpression) &&
        isEqualTokens(node.colon, other.colon) &&
        isEqualNodes(node.elseExpression, other.elseExpression);
  }

  @override
  bool visitConfiguration(Configuration node) {
    Configuration other = _other as Configuration;
    return isEqualTokens(node.ifKeyword, other.ifKeyword) &&
        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        isEqualNodes(node.name, other.name) &&
        isEqualTokens(node.equalToken, other.equalToken) &&
        isEqualNodes(node.value, other.value) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
        isEqualNodes(node.libraryUri, other.libraryUri);
  }

  @override
  bool visitConstructorDeclaration(ConstructorDeclaration node) {
    ConstructorDeclaration other = _other as ConstructorDeclaration;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.externalKeyword, other.externalKeyword) &&
        isEqualTokens(node.constKeyword, other.constKeyword) &&
        isEqualTokens(node.factoryKeyword, other.factoryKeyword) &&
        isEqualNodes(node.returnType, other.returnType) &&
        isEqualTokens(node.period, other.period) &&
        isEqualNodes(node.name, other.name) &&
        isEqualNodes(node.parameters, other.parameters) &&
        isEqualTokens(node.separator, other.separator) &&
        _isEqualNodeLists(node.initializers, other.initializers) &&
        isEqualNodes(node.redirectedConstructor, other.redirectedConstructor) &&
        isEqualNodes(node.body, other.body);
  }

  @override
  bool visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
    ConstructorFieldInitializer other = _other as ConstructorFieldInitializer;
    return isEqualTokens(node.thisKeyword, other.thisKeyword) &&
        isEqualTokens(node.period, other.period) &&
        isEqualNodes(node.fieldName, other.fieldName) &&
        isEqualTokens(node.equals, other.equals) &&
        isEqualNodes(node.expression, other.expression);
  }

  @override
  bool visitConstructorName(ConstructorName node) {
    ConstructorName other = _other as ConstructorName;
    return isEqualNodes(node.type, other.type) &&
        isEqualTokens(node.period, other.period) &&
        isEqualNodes(node.name, other.name);
  }

  @override
  bool visitContinueStatement(ContinueStatement node) {
    ContinueStatement other = _other as ContinueStatement;
    return isEqualTokens(node.continueKeyword, other.continueKeyword) &&
        isEqualNodes(node.label, other.label) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitDeclaredIdentifier(DeclaredIdentifier node) {
    DeclaredIdentifier other = _other as DeclaredIdentifier;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.keyword, other.keyword) &&
        isEqualNodes(node.type, other.type) &&
        isEqualNodes(node.identifier, other.identifier);
  }

  @override
  bool visitDefaultFormalParameter(DefaultFormalParameter node) {
    DefaultFormalParameter other = _other as DefaultFormalParameter;
    return isEqualNodes(node.parameter, other.parameter) &&
        node.kind == other.kind &&
        isEqualTokens(node.separator, other.separator) &&
        isEqualNodes(node.defaultValue, other.defaultValue);
  }

  @override
  bool visitDoStatement(DoStatement node) {
    DoStatement other = _other as DoStatement;
    return isEqualTokens(node.doKeyword, other.doKeyword) &&
        isEqualNodes(node.body, other.body) &&
        isEqualTokens(node.whileKeyword, other.whileKeyword) &&
        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        isEqualNodes(node.condition, other.condition) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitDottedName(DottedName node) {
    DottedName other = _other as DottedName;
    return _isEqualNodeLists(node.components, other.components);
  }

  @override
  bool visitDoubleLiteral(DoubleLiteral node) {
    DoubleLiteral other = _other as DoubleLiteral;
    return isEqualTokens(node.literal, other.literal) &&
        node.value == other.value;
  }

  @override
  bool visitEmptyFunctionBody(EmptyFunctionBody node) {
    EmptyFunctionBody other = _other as EmptyFunctionBody;
    return isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitEmptyStatement(EmptyStatement node) {
    EmptyStatement other = _other as EmptyStatement;
    return isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitEnumConstantDeclaration(EnumConstantDeclaration node) {
    EnumConstantDeclaration other = _other as EnumConstantDeclaration;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualNodes(node.name, other.name);
  }

  @override
  bool visitEnumDeclaration(EnumDeclaration node) {
    EnumDeclaration other = _other as EnumDeclaration;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.enumKeyword, other.enumKeyword) &&
        isEqualNodes(node.name, other.name) &&
        isEqualTokens(node.leftBracket, other.leftBracket) &&
        _isEqualNodeLists(node.constants, other.constants) &&
        isEqualTokens(node.rightBracket, other.rightBracket);
  }

  @override
  bool visitExportDirective(ExportDirective node) {
    ExportDirective other = _other as ExportDirective;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.keyword, other.keyword) &&
        isEqualNodes(node.uri, other.uri) &&
        _isEqualNodeLists(node.combinators, other.combinators) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitExpressionFunctionBody(ExpressionFunctionBody node) {
    ExpressionFunctionBody other = _other as ExpressionFunctionBody;
    return isEqualTokens(node.functionDefinition, other.functionDefinition) &&
        isEqualNodes(node.expression, other.expression) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitExpressionStatement(ExpressionStatement node) {
    ExpressionStatement other = _other as ExpressionStatement;
    return isEqualNodes(node.expression, other.expression) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitExtendsClause(ExtendsClause node) {
    ExtendsClause other = _other as ExtendsClause;
    return isEqualTokens(node.extendsKeyword, other.extendsKeyword) &&
        isEqualNodes(node.superclass, other.superclass);
  }

  @override
  bool visitFieldDeclaration(FieldDeclaration node) {
    FieldDeclaration other = _other as FieldDeclaration;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.staticKeyword, other.staticKeyword) &&
        isEqualNodes(node.fields, other.fields) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitFieldFormalParameter(FieldFormalParameter node) {
    FieldFormalParameter other = _other as FieldFormalParameter;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.keyword, other.keyword) &&
        isEqualNodes(node.type, other.type) &&
        isEqualTokens(node.thisKeyword, other.thisKeyword) &&
        isEqualTokens(node.period, other.period) &&
        isEqualNodes(node.identifier, other.identifier);
  }

  @override
  bool visitForEachStatement(ForEachStatement node) {
    ForEachStatement other = _other as ForEachStatement;
    return isEqualTokens(node.forKeyword, other.forKeyword) &&
        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        isEqualNodes(node.loopVariable, other.loopVariable) &&
        isEqualTokens(node.inKeyword, other.inKeyword) &&
        isEqualNodes(node.iterable, other.iterable) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
        isEqualNodes(node.body, other.body);
  }

  @override
  bool visitFormalParameterList(FormalParameterList node) {
    FormalParameterList other = _other as FormalParameterList;
    return isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        _isEqualNodeLists(node.parameters, other.parameters) &&
        isEqualTokens(node.leftDelimiter, other.leftDelimiter) &&
        isEqualTokens(node.rightDelimiter, other.rightDelimiter) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis);
  }

  @override
  bool visitForStatement(ForStatement node) {
    ForStatement other = _other as ForStatement;
    return isEqualTokens(node.forKeyword, other.forKeyword) &&
        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        isEqualNodes(node.variables, other.variables) &&
        isEqualNodes(node.initialization, other.initialization) &&
        isEqualTokens(node.leftSeparator, other.leftSeparator) &&
        isEqualNodes(node.condition, other.condition) &&
        isEqualTokens(node.rightSeparator, other.rightSeparator) &&
        _isEqualNodeLists(node.updaters, other.updaters) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
        isEqualNodes(node.body, other.body);
  }

  @override
  bool visitFunctionDeclaration(FunctionDeclaration node) {
    FunctionDeclaration other = _other as FunctionDeclaration;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.externalKeyword, other.externalKeyword) &&
        isEqualNodes(node.returnType, other.returnType) &&
        isEqualTokens(node.propertyKeyword, other.propertyKeyword) &&
        isEqualNodes(node.name, other.name) &&
        isEqualNodes(node.functionExpression, other.functionExpression);
  }

  @override
  bool visitFunctionDeclarationStatement(FunctionDeclarationStatement node) {
    FunctionDeclarationStatement other = _other as FunctionDeclarationStatement;
    return isEqualNodes(node.functionDeclaration, other.functionDeclaration);
  }

  @override
  bool visitFunctionExpression(FunctionExpression node) {
    FunctionExpression other = _other as FunctionExpression;
    return isEqualNodes(node.parameters, other.parameters) &&
        isEqualNodes(node.body, other.body);
  }

  @override
  bool visitFunctionExpressionInvocation(FunctionExpressionInvocation node) {
    FunctionExpressionInvocation other = _other as FunctionExpressionInvocation;
    return isEqualNodes(node.function, other.function) &&
        isEqualNodes(node.argumentList, other.argumentList);
  }

  @override
  bool visitFunctionTypeAlias(FunctionTypeAlias node) {
    FunctionTypeAlias other = _other as FunctionTypeAlias;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.typedefKeyword, other.typedefKeyword) &&
        isEqualNodes(node.returnType, other.returnType) &&
        isEqualNodes(node.name, other.name) &&
        isEqualNodes(node.typeParameters, other.typeParameters) &&
        isEqualNodes(node.parameters, other.parameters) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
    FunctionTypedFormalParameter other = _other as FunctionTypedFormalParameter;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualNodes(node.returnType, other.returnType) &&
        isEqualNodes(node.identifier, other.identifier) &&
        isEqualNodes(node.parameters, other.parameters);
  }

  @override
  bool visitHideCombinator(HideCombinator node) {
    HideCombinator other = _other as HideCombinator;
    return isEqualTokens(node.keyword, other.keyword) &&
        _isEqualNodeLists(node.hiddenNames, other.hiddenNames);
  }

  @override
  bool visitIfStatement(IfStatement node) {
    IfStatement other = _other as IfStatement;
    return isEqualTokens(node.ifKeyword, other.ifKeyword) &&
        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        isEqualNodes(node.condition, other.condition) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
        isEqualNodes(node.thenStatement, other.thenStatement) &&
        isEqualTokens(node.elseKeyword, other.elseKeyword) &&
        isEqualNodes(node.elseStatement, other.elseStatement);
  }

  @override
  bool visitImplementsClause(ImplementsClause node) {
    ImplementsClause other = _other as ImplementsClause;
    return isEqualTokens(node.implementsKeyword, other.implementsKeyword) &&
        _isEqualNodeLists(node.interfaces, other.interfaces);
  }

  @override
  bool visitImportDirective(ImportDirective node) {
    ImportDirective other = _other as ImportDirective;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.keyword, other.keyword) &&
        isEqualNodes(node.uri, other.uri) &&
        isEqualTokens(node.deferredKeyword, other.deferredKeyword) &&
        isEqualTokens(node.asKeyword, other.asKeyword) &&
        isEqualNodes(node.prefix, other.prefix) &&
        _isEqualNodeLists(node.combinators, other.combinators) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitIndexExpression(IndexExpression node) {
    IndexExpression other = _other as IndexExpression;
    return isEqualNodes(node.target, other.target) &&
        isEqualTokens(node.leftBracket, other.leftBracket) &&
        isEqualNodes(node.index, other.index) &&
        isEqualTokens(node.rightBracket, other.rightBracket);
  }

  @override
  bool visitInstanceCreationExpression(InstanceCreationExpression node) {
    InstanceCreationExpression other = _other as InstanceCreationExpression;
    return isEqualTokens(node.keyword, other.keyword) &&
        isEqualNodes(node.constructorName, other.constructorName) &&
        isEqualNodes(node.argumentList, other.argumentList);
  }

  @override
  bool visitIntegerLiteral(IntegerLiteral node) {
    IntegerLiteral other = _other as IntegerLiteral;
    return isEqualTokens(node.literal, other.literal) &&
        (node.value == other.value);
  }

  @override
  bool visitInterpolationExpression(InterpolationExpression node) {
    InterpolationExpression other = _other as InterpolationExpression;
    return isEqualTokens(node.leftBracket, other.leftBracket) &&
        isEqualNodes(node.expression, other.expression) &&
        isEqualTokens(node.rightBracket, other.rightBracket);
  }

  @override
  bool visitInterpolationString(InterpolationString node) {
    InterpolationString other = _other as InterpolationString;
    return isEqualTokens(node.contents, other.contents) &&
        node.value == other.value;
  }

  @override
  bool visitIsExpression(IsExpression node) {
    IsExpression other = _other as IsExpression;
    return isEqualNodes(node.expression, other.expression) &&
        isEqualTokens(node.isOperator, other.isOperator) &&
        isEqualTokens(node.notOperator, other.notOperator) &&
        isEqualNodes(node.type, other.type);
  }

  @override
  bool visitLabel(Label node) {
    Label other = _other as Label;
    return isEqualNodes(node.label, other.label) &&
        isEqualTokens(node.colon, other.colon);
  }

  @override
  bool visitLabeledStatement(LabeledStatement node) {
    LabeledStatement other = _other as LabeledStatement;
    return _isEqualNodeLists(node.labels, other.labels) &&
        isEqualNodes(node.statement, other.statement);
  }

  @override
  bool visitLibraryDirective(LibraryDirective node) {
    LibraryDirective other = _other as LibraryDirective;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.libraryKeyword, other.libraryKeyword) &&
        isEqualNodes(node.name, other.name) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitLibraryIdentifier(LibraryIdentifier node) {
    LibraryIdentifier other = _other as LibraryIdentifier;
    return _isEqualNodeLists(node.components, other.components);
  }

  @override
  bool visitListLiteral(ListLiteral node) {
    ListLiteral other = _other as ListLiteral;
    return isEqualTokens(node.constKeyword, other.constKeyword) &&
        isEqualNodes(node.typeArguments, other.typeArguments) &&
        isEqualTokens(node.leftBracket, other.leftBracket) &&
        _isEqualNodeLists(node.elements, other.elements) &&
        isEqualTokens(node.rightBracket, other.rightBracket);
  }

  @override
  bool visitMapLiteral(MapLiteral node) {
    MapLiteral other = _other as MapLiteral;
    return isEqualTokens(node.constKeyword, other.constKeyword) &&
        isEqualNodes(node.typeArguments, other.typeArguments) &&
        isEqualTokens(node.leftBracket, other.leftBracket) &&
        _isEqualNodeLists(node.entries, other.entries) &&
        isEqualTokens(node.rightBracket, other.rightBracket);
  }

  @override
  bool visitMapLiteralEntry(MapLiteralEntry node) {
    MapLiteralEntry other = _other as MapLiteralEntry;
    return isEqualNodes(node.key, other.key) &&
        isEqualTokens(node.separator, other.separator) &&
        isEqualNodes(node.value, other.value);
  }

  @override
  bool visitMethodDeclaration(MethodDeclaration node) {
    MethodDeclaration other = _other as MethodDeclaration;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.externalKeyword, other.externalKeyword) &&
        isEqualTokens(node.modifierKeyword, other.modifierKeyword) &&
        isEqualNodes(node.returnType, other.returnType) &&
        isEqualTokens(node.propertyKeyword, other.propertyKeyword) &&
        isEqualTokens(node.propertyKeyword, other.propertyKeyword) &&
        isEqualNodes(node.name, other.name) &&
        isEqualNodes(node.parameters, other.parameters) &&
        isEqualNodes(node.body, other.body);
  }

  @override
  bool visitMethodInvocation(MethodInvocation node) {
    MethodInvocation other = _other as MethodInvocation;
    return isEqualNodes(node.target, other.target) &&
        isEqualTokens(node.operator, other.operator) &&
        isEqualNodes(node.methodName, other.methodName) &&
        isEqualNodes(node.argumentList, other.argumentList);
  }

  @override
  bool visitNamedExpression(NamedExpression node) {
    NamedExpression other = _other as NamedExpression;
    return isEqualNodes(node.name, other.name) &&
        isEqualNodes(node.expression, other.expression);
  }

  @override
  bool visitNativeClause(NativeClause node) {
    NativeClause other = _other as NativeClause;
    return isEqualTokens(node.nativeKeyword, other.nativeKeyword) &&
        isEqualNodes(node.name, other.name);
  }

  @override
  bool visitNativeFunctionBody(NativeFunctionBody node) {
    NativeFunctionBody other = _other as NativeFunctionBody;
    return isEqualTokens(node.nativeKeyword, other.nativeKeyword) &&
        isEqualNodes(node.stringLiteral, other.stringLiteral) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitNullLiteral(NullLiteral node) {
    NullLiteral other = _other as NullLiteral;
    return isEqualTokens(node.literal, other.literal);
  }

  @override
  bool visitParenthesizedExpression(ParenthesizedExpression node) {
    ParenthesizedExpression other = _other as ParenthesizedExpression;
    return isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        isEqualNodes(node.expression, other.expression) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis);
  }

  @override
  bool visitPartDirective(PartDirective node) {
    PartDirective other = _other as PartDirective;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.partKeyword, other.partKeyword) &&
        isEqualNodes(node.uri, other.uri) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitPartOfDirective(PartOfDirective node) {
    PartOfDirective other = _other as PartOfDirective;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.partKeyword, other.partKeyword) &&
        isEqualTokens(node.ofKeyword, other.ofKeyword) &&
        isEqualNodes(node.libraryName, other.libraryName) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitPostfixExpression(PostfixExpression node) {
    PostfixExpression other = _other as PostfixExpression;
    return isEqualNodes(node.operand, other.operand) &&
        isEqualTokens(node.operator, other.operator);
  }

  @override
  bool visitPrefixedIdentifier(PrefixedIdentifier node) {
    PrefixedIdentifier other = _other as PrefixedIdentifier;
    return isEqualNodes(node.prefix, other.prefix) &&
        isEqualTokens(node.period, other.period) &&
        isEqualNodes(node.identifier, other.identifier);
  }

  @override
  bool visitPrefixExpression(PrefixExpression node) {
    PrefixExpression other = _other as PrefixExpression;
    return isEqualTokens(node.operator, other.operator) &&
        isEqualNodes(node.operand, other.operand);
  }

  @override
  bool visitPropertyAccess(PropertyAccess node) {
    PropertyAccess other = _other as PropertyAccess;
    return isEqualNodes(node.target, other.target) &&
        isEqualTokens(node.operator, other.operator) &&
        isEqualNodes(node.propertyName, other.propertyName);
  }

  @override
  bool visitRedirectingConstructorInvocation(
      RedirectingConstructorInvocation node) {
    RedirectingConstructorInvocation other =
        _other as RedirectingConstructorInvocation;
    return isEqualTokens(node.thisKeyword, other.thisKeyword) &&
        isEqualTokens(node.period, other.period) &&
        isEqualNodes(node.constructorName, other.constructorName) &&
        isEqualNodes(node.argumentList, other.argumentList);
  }

  @override
  bool visitRethrowExpression(RethrowExpression node) {
    RethrowExpression other = _other as RethrowExpression;
    return isEqualTokens(node.rethrowKeyword, other.rethrowKeyword);
  }

  @override
  bool visitReturnStatement(ReturnStatement node) {
    ReturnStatement other = _other as ReturnStatement;
    return isEqualTokens(node.returnKeyword, other.returnKeyword) &&
        isEqualNodes(node.expression, other.expression) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitScriptTag(ScriptTag node) {
    ScriptTag other = _other as ScriptTag;
    return isEqualTokens(node.scriptTag, other.scriptTag);
  }

  @override
  bool visitShowCombinator(ShowCombinator node) {
    ShowCombinator other = _other as ShowCombinator;
    return isEqualTokens(node.keyword, other.keyword) &&
        _isEqualNodeLists(node.shownNames, other.shownNames);
  }

  @override
  bool visitSimpleFormalParameter(SimpleFormalParameter node) {
    SimpleFormalParameter other = _other as SimpleFormalParameter;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.keyword, other.keyword) &&
        isEqualNodes(node.type, other.type) &&
        isEqualNodes(node.identifier, other.identifier);
  }

  @override
  bool visitSimpleIdentifier(SimpleIdentifier node) {
    SimpleIdentifier other = _other as SimpleIdentifier;
    return isEqualTokens(node.token, other.token);
  }

  @override
  bool visitSimpleStringLiteral(SimpleStringLiteral node) {
    SimpleStringLiteral other = _other as SimpleStringLiteral;
    return isEqualTokens(node.literal, other.literal) &&
        (node.value == other.value);
  }

  @override
  bool visitStringInterpolation(StringInterpolation node) {
    StringInterpolation other = _other as StringInterpolation;
    return _isEqualNodeLists(node.elements, other.elements);
  }

  @override
  bool visitSuperConstructorInvocation(SuperConstructorInvocation node) {
    SuperConstructorInvocation other = _other as SuperConstructorInvocation;
    return isEqualTokens(node.superKeyword, other.superKeyword) &&
        isEqualTokens(node.period, other.period) &&
        isEqualNodes(node.constructorName, other.constructorName) &&
        isEqualNodes(node.argumentList, other.argumentList);
  }

  @override
  bool visitSuperExpression(SuperExpression node) {
    SuperExpression other = _other as SuperExpression;
    return isEqualTokens(node.superKeyword, other.superKeyword);
  }

  @override
  bool visitSwitchCase(SwitchCase node) {
    SwitchCase other = _other as SwitchCase;
    return _isEqualNodeLists(node.labels, other.labels) &&
        isEqualTokens(node.keyword, other.keyword) &&
        isEqualNodes(node.expression, other.expression) &&
        isEqualTokens(node.colon, other.colon) &&
        _isEqualNodeLists(node.statements, other.statements);
  }

  @override
  bool visitSwitchDefault(SwitchDefault node) {
    SwitchDefault other = _other as SwitchDefault;
    return _isEqualNodeLists(node.labels, other.labels) &&
        isEqualTokens(node.keyword, other.keyword) &&
        isEqualTokens(node.colon, other.colon) &&
        _isEqualNodeLists(node.statements, other.statements);
  }

  @override
  bool visitSwitchStatement(SwitchStatement node) {
    SwitchStatement other = _other as SwitchStatement;
    return isEqualTokens(node.switchKeyword, other.switchKeyword) &&
        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        isEqualNodes(node.expression, other.expression) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
        isEqualTokens(node.leftBracket, other.leftBracket) &&
        _isEqualNodeLists(node.members, other.members) &&
        isEqualTokens(node.rightBracket, other.rightBracket);
  }

  @override
  bool visitSymbolLiteral(SymbolLiteral node) {
    SymbolLiteral other = _other as SymbolLiteral;
    return isEqualTokens(node.poundSign, other.poundSign) &&
        _isEqualTokenLists(node.components, other.components);
  }

  @override
  bool visitThisExpression(ThisExpression node) {
    ThisExpression other = _other as ThisExpression;
    return isEqualTokens(node.thisKeyword, other.thisKeyword);
  }

  @override
  bool visitThrowExpression(ThrowExpression node) {
    ThrowExpression other = _other as ThrowExpression;
    return isEqualTokens(node.throwKeyword, other.throwKeyword) &&
        isEqualNodes(node.expression, other.expression);
  }

  @override
  bool visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
    TopLevelVariableDeclaration other = _other as TopLevelVariableDeclaration;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualNodes(node.variables, other.variables) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitTryStatement(TryStatement node) {
    TryStatement other = _other as TryStatement;
    return isEqualTokens(node.tryKeyword, other.tryKeyword) &&
        isEqualNodes(node.body, other.body) &&
        _isEqualNodeLists(node.catchClauses, other.catchClauses) &&
        isEqualTokens(node.finallyKeyword, other.finallyKeyword) &&
        isEqualNodes(node.finallyBlock, other.finallyBlock);
  }

  @override
  bool visitTypeArgumentList(TypeArgumentList node) {
    TypeArgumentList other = _other as TypeArgumentList;
    return isEqualTokens(node.leftBracket, other.leftBracket) &&
        _isEqualNodeLists(node.arguments, other.arguments) &&
        isEqualTokens(node.rightBracket, other.rightBracket);
  }

  @override
  bool visitTypeName(TypeName node) {
    TypeName other = _other as TypeName;
    return isEqualNodes(node.name, other.name) &&
        isEqualNodes(node.typeArguments, other.typeArguments);
  }

  @override
  bool visitTypeParameter(TypeParameter node) {
    TypeParameter other = _other as TypeParameter;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualNodes(node.name, other.name) &&
        isEqualTokens(node.extendsKeyword, other.extendsKeyword) &&
        isEqualNodes(node.bound, other.bound);
  }

  @override
  bool visitTypeParameterList(TypeParameterList node) {
    TypeParameterList other = _other as TypeParameterList;
    return isEqualTokens(node.leftBracket, other.leftBracket) &&
        _isEqualNodeLists(node.typeParameters, other.typeParameters) &&
        isEqualTokens(node.rightBracket, other.rightBracket);
  }

  @override
  bool visitVariableDeclaration(VariableDeclaration node) {
    VariableDeclaration other = _other as VariableDeclaration;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualNodes(node.name, other.name) &&
        isEqualTokens(node.equals, other.equals) &&
        isEqualNodes(node.initializer, other.initializer);
  }

  @override
  bool visitVariableDeclarationList(VariableDeclarationList node) {
    VariableDeclarationList other = _other as VariableDeclarationList;
    return isEqualNodes(
            node.documentationComment, other.documentationComment) &&
        _isEqualNodeLists(node.metadata, other.metadata) &&
        isEqualTokens(node.keyword, other.keyword) &&
        isEqualNodes(node.type, other.type) &&
        _isEqualNodeLists(node.variables, other.variables);
  }

  @override
  bool visitVariableDeclarationStatement(VariableDeclarationStatement node) {
    VariableDeclarationStatement other = _other as VariableDeclarationStatement;
    return isEqualNodes(node.variables, other.variables) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  @override
  bool visitWhileStatement(WhileStatement node) {
    WhileStatement other = _other as WhileStatement;
    return isEqualTokens(node.whileKeyword, other.whileKeyword) &&
        isEqualTokens(node.leftParenthesis, other.leftParenthesis) &&
        isEqualNodes(node.condition, other.condition) &&
        isEqualTokens(node.rightParenthesis, other.rightParenthesis) &&
        isEqualNodes(node.body, other.body);
  }

  @override
  bool visitWithClause(WithClause node) {
    WithClause other = _other as WithClause;
    return isEqualTokens(node.withKeyword, other.withKeyword) &&
        _isEqualNodeLists(node.mixinTypes, other.mixinTypes);
  }

  @override
  bool visitYieldStatement(YieldStatement node) {
    YieldStatement other = _other as YieldStatement;
    return isEqualTokens(node.yieldKeyword, other.yieldKeyword) &&
        isEqualNodes(node.expression, other.expression) &&
        isEqualTokens(node.semicolon, other.semicolon);
  }

  /**
   * Return `true` if the [first] and [second] lists of AST nodes have the same
   * size and corresponding elements are equal.
   */
  bool _isEqualNodeLists(NodeList first, NodeList second) {
    if (first == null) {
      return second == null;
    } else if (second == null) {
      return false;
    }
    int size = first.length;
    if (second.length != size) {
      return false;
    }
    for (int i = 0; i < size; i++) {
      if (!isEqualNodes(first[i], second[i])) {
        return false;
      }
    }
    return true;
  }

  /**
   * Return `true` if the [first] and [second] lists of tokens have the same
   * length and corresponding elements are equal.
   */
  bool _isEqualTokenLists(List<Token> first, List<Token> second) {
    int length = first.length;
    if (second.length != length) {
      return false;
    }
    for (int i = 0; i < length; i++) {
      if (!isEqualTokens(first[i], second[i])) {
        return false;
      }
    }
    return true;
  }

  /**
   * Return `true` if the [first] and [second] nodes are equal.
   */
  static bool equalNodes(AstNode first, AstNode second) {
    AstComparator comparator = new AstComparator();
    return comparator.isEqualNodes(first, second);
  }
}

/**
 * Instances of the class [ConstantEvaluator] evaluate constant expressions to
 * produce their compile-time value.
 *
 * According to the Dart Language Specification:
 *
 * > A constant expression is one of the following:
 * >
 * > * A literal number.
 * > * A literal boolean.
 * > * A literal string where any interpolated expression is a compile-time
 * >   constant that evaluates to a numeric, string or boolean value or to
 * >   **null**.
 * > * A literal symbol.
 * > * **null**.
 * > * A qualified reference to a static constant variable.
 * > * An identifier expression that denotes a constant variable, class or type
 * >   alias.
 * > * A constant constructor invocation.
 * > * A constant list literal.
 * > * A constant map literal.
 * > * A simple or qualified identifier denoting a top-level function or a
 * >   static method.
 * > * A parenthesized expression _(e)_ where _e_ is a constant expression.
 * > * <span>
 * >   An expression of the form <i>identical(e<sub>1</sub>, e<sub>2</sub>)</i>
 * >   where <i>e<sub>1</sub></i> and <i>e<sub>2</sub></i> are constant
 * >   expressions and <i>identical()</i> is statically bound to the predefined
 * >   dart function <i>identical()</i> discussed above.
 * >   </span>
 * > * <span>
 * >   An expression of one of the forms <i>e<sub>1</sub> == e<sub>2</sub></i>
 * >   or <i>e<sub>1</sub> != e<sub>2</sub></i> where <i>e<sub>1</sub></i> and
 * >   <i>e<sub>2</sub></i> are constant expressions that evaluate to a
 * >   numeric, string or boolean value.
 * >   </span>
 * > * <span>
 * >   An expression of one of the forms <i>!e</i>, <i>e<sub>1</sub> &amp;&amp;
 * >   e<sub>2</sub></i> or <i>e<sub>1</sub> || e<sub>2</sub></i>, where
 * >   <i>e</i>, <i>e<sub>1</sub></i> and <i>e<sub>2</sub></i> are constant
 * >   expressions that evaluate to a boolean value.
 * >   </span>
 * > * <span>
 * >   An expression of one of the forms <i>~e</i>, <i>e<sub>1</sub> ^
 * >   e<sub>2</sub></i>, <i>e<sub>1</sub> &amp; e<sub>2</sub></i>,
 * >   <i>e<sub>1</sub> | e<sub>2</sub></i>, <i>e<sub>1</sub> &gt;&gt;
 * >   e<sub>2</sub></i> or <i>e<sub>1</sub> &lt;&lt; e<sub>2</sub></i>, where
 * >   <i>e</i>, <i>e<sub>1</sub></i> and <i>e<sub>2</sub></i> are constant
 * >   expressions that evaluate to an integer value or to <b>null</b>.
 * >   </span>
 * > * <span>
 * >   An expression of one of the forms <i>-e</i>, <i>e<sub>1</sub> +
 * >   e<sub>2</sub></i>, <i>e<sub>1</sub> -e<sub>2</sub></i>,
 * >   <i>e<sub>1</sub> * e<sub>2</sub></i>, <i>e<sub>1</sub> /
 * >   e<sub>2</sub></i>, <i>e<sub>1</sub> ~/ e<sub>2</sub></i>,
 * >   <i>e<sub>1</sub> &gt; e<sub>2</sub></i>, <i>e<sub>1</sub> &lt;
 * >   e<sub>2</sub></i>, <i>e<sub>1</sub> &gt;= e<sub>2</sub></i>,
 * >   <i>e<sub>1</sub> &lt;= e<sub>2</sub></i> or <i>e<sub>1</sub> %
 * >   e<sub>2</sub></i>, where <i>e</i>, <i>e<sub>1</sub></i> and
 * >   <i>e<sub>2</sub></i> are constant expressions that evaluate to a numeric
 * >   value or to <b>null</b>.
 * >   </span>
 * > * <span>
 * >   An expression of the form <i>e<sub>1</sub> ? e<sub>2</sub> :
 * >   e<sub>3</sub></i> where <i>e<sub>1</sub></i>, <i>e<sub>2</sub></i> and
 * >   <i>e<sub>3</sub></i> are constant expressions, and <i>e<sub>1</sub></i>
 * >   evaluates to a boolean value.
 * >   </span>
 *
 * The values returned by instances of this class are therefore `null` and
 * instances of the classes `Boolean`, `BigInteger`, `Double`, `String`, and
 * `DartObject`.
 *
 * In addition, this class defines several values that can be returned to
 * indicate various conditions encountered during evaluation. These are
 * documented with the static fields that define those values.
 */
class ConstantEvaluator extends GeneralizingAstVisitor<Object> {
  /**
   * The value returned for expressions (or non-expression nodes) that are not
   * compile-time constant expressions.
   */
  static Object NOT_A_CONSTANT = new Object();

  @override
  Object visitAdjacentStrings(AdjacentStrings node) {
    StringBuffer buffer = new StringBuffer();
    for (StringLiteral string in node.strings) {
      Object value = string.accept(this);
      if (identical(value, NOT_A_CONSTANT)) {
        return value;
      }
      buffer.write(value);
    }
    return buffer.toString();
  }

  @override
  Object visitBinaryExpression(BinaryExpression node) {
    Object leftOperand = node.leftOperand.accept(this);
    if (identical(leftOperand, NOT_A_CONSTANT)) {
      return leftOperand;
    }
    Object rightOperand = node.rightOperand.accept(this);
    if (identical(rightOperand, NOT_A_CONSTANT)) {
      return rightOperand;
    }
    while (true) {
      if (node.operator.type == TokenType.AMPERSAND) {
        // integer or {@code null}
        if (leftOperand is int && rightOperand is int) {
          return leftOperand & rightOperand;
        }
      } else if (node.operator.type == TokenType.AMPERSAND_AMPERSAND) {
        // boolean or {@code null}
        if (leftOperand is bool && rightOperand is bool) {
          return leftOperand && rightOperand;
        }
      } else if (node.operator.type == TokenType.BANG_EQ) {
        // numeric, string, boolean, or {@code null}
        if (leftOperand is bool && rightOperand is bool) {
          return leftOperand != rightOperand;
        } else if (leftOperand is num && rightOperand is num) {
          return leftOperand != rightOperand;
        } else if (leftOperand is String && rightOperand is String) {
          return leftOperand != rightOperand;
        }
      } else if (node.operator.type == TokenType.BAR) {
        // integer or {@code null}
        if (leftOperand is int && rightOperand is int) {
          return leftOperand | rightOperand;
        }
      } else if (node.operator.type == TokenType.BAR_BAR) {
        // boolean or {@code null}
        if (leftOperand is bool && rightOperand is bool) {
          return leftOperand || rightOperand;
        }
      } else if (node.operator.type == TokenType.CARET) {
        // integer or {@code null}
        if (leftOperand is int && rightOperand is int) {
          return leftOperand ^ rightOperand;
        }
      } else if (node.operator.type == TokenType.EQ_EQ) {
        // numeric, string, boolean, or {@code null}
        if (leftOperand is bool && rightOperand is bool) {
          return leftOperand == rightOperand;
        } else if (leftOperand is num && rightOperand is num) {
          return leftOperand == rightOperand;
        } else if (leftOperand is String && rightOperand is String) {
          return leftOperand == rightOperand;
        }
      } else if (node.operator.type == TokenType.GT) {
        // numeric or {@code null}
        if (leftOperand is num && rightOperand is num) {
          return leftOperand.compareTo(rightOperand) > 0;
        }
      } else if (node.operator.type == TokenType.GT_EQ) {
        // numeric or {@code null}
        if (leftOperand is num && rightOperand is num) {
          return leftOperand.compareTo(rightOperand) >= 0;
        }
      } else if (node.operator.type == TokenType.GT_GT) {
        // integer or {@code null}
        if (leftOperand is int && rightOperand is int) {
          return leftOperand >> rightOperand;
        }
      } else if (node.operator.type == TokenType.LT) {
        // numeric or {@code null}
        if (leftOperand is num && rightOperand is num) {
          return leftOperand.compareTo(rightOperand) < 0;
        }
      } else if (node.operator.type == TokenType.LT_EQ) {
        // numeric or {@code null}
        if (leftOperand is num && rightOperand is num) {
          return leftOperand.compareTo(rightOperand) <= 0;
        }
      } else if (node.operator.type == TokenType.LT_LT) {
        // integer or {@code null}
        if (leftOperand is int && rightOperand is int) {
          return leftOperand << rightOperand;
        }
      } else if (node.operator.type == TokenType.MINUS) {
        // numeric or {@code null}
        if (leftOperand is num && rightOperand is num) {
          return leftOperand - rightOperand;
        }
      } else if (node.operator.type == TokenType.PERCENT) {
        // numeric or {@code null}
        if (leftOperand is num && rightOperand is num) {
          return leftOperand.remainder(rightOperand);
        }
      } else if (node.operator.type == TokenType.PLUS) {
        // numeric or {@code null}
        if (leftOperand is num && rightOperand is num) {
          return leftOperand + rightOperand;
        }
      } else if (node.operator.type == TokenType.STAR) {
        // numeric or {@code null}
        if (leftOperand is num && rightOperand is num) {
          return leftOperand * rightOperand;
        }
      } else if (node.operator.type == TokenType.SLASH) {
        // numeric or {@code null}
        if (leftOperand is num && rightOperand is num) {
          return leftOperand / rightOperand;
        }
      } else if (node.operator.type == TokenType.TILDE_SLASH) {
        // numeric or {@code null}
        if (leftOperand is num && rightOperand is num) {
          return leftOperand ~/ rightOperand;
        }
      } else {}
      break;
    }
    // TODO(brianwilkerson) This doesn't handle numeric conversions.
    return visitExpression(node);
  }

  @override
  Object visitBooleanLiteral(BooleanLiteral node) => node.value ? true : false;

  @override
  Object visitDoubleLiteral(DoubleLiteral node) => node.value;

  @override
  Object visitIntegerLiteral(IntegerLiteral node) => node.value;

  @override
  Object visitInterpolationExpression(InterpolationExpression node) {
    Object value = node.expression.accept(this);
    if (value == null || value is bool || value is String || value is num) {
      return value;
    }
    return NOT_A_CONSTANT;
  }

  @override
  Object visitInterpolationString(InterpolationString node) => node.value;

  @override
  Object visitListLiteral(ListLiteral node) {
    List<Object> list = new List<Object>();
    for (Expression element in node.elements) {
      Object value = element.accept(this);
      if (identical(value, NOT_A_CONSTANT)) {
        return value;
      }
      list.add(value);
    }
    return list;
  }

  @override
  Object visitMapLiteral(MapLiteral node) {
    HashMap<String, Object> map = new HashMap<String, Object>();
    for (MapLiteralEntry entry in node.entries) {
      Object key = entry.key.accept(this);
      Object value = entry.value.accept(this);
      if (key is! String || identical(value, NOT_A_CONSTANT)) {
        return NOT_A_CONSTANT;
      }
      map[(key as String)] = value;
    }
    return map;
  }

  @override
  Object visitMethodInvocation(MethodInvocation node) => visitNode(node);

  @override
  Object visitNode(AstNode node) => NOT_A_CONSTANT;

  @override
  Object visitNullLiteral(NullLiteral node) => null;

  @override
  Object visitParenthesizedExpression(ParenthesizedExpression node) =>
      node.expression.accept(this);

  @override
  Object visitPrefixedIdentifier(PrefixedIdentifier node) =>
      _getConstantValue(null);

  @override
  Object visitPrefixExpression(PrefixExpression node) {
    Object operand = node.operand.accept(this);
    if (identical(operand, NOT_A_CONSTANT)) {
      return operand;
    }
    while (true) {
      if (node.operator.type == TokenType.BANG) {
        if (identical(operand, true)) {
          return false;
        } else if (identical(operand, false)) {
          return true;
        }
      } else if (node.operator.type == TokenType.TILDE) {
        if (operand is int) {
          return ~operand;
        }
      } else if (node.operator.type == TokenType.MINUS) {
        if (operand == null) {
          return null;
        } else if (operand is num) {
          return -operand;
        }
      } else {}
      break;
    }
    return NOT_A_CONSTANT;
  }

  @override
  Object visitPropertyAccess(PropertyAccess node) => _getConstantValue(null);

  @override
  Object visitSimpleIdentifier(SimpleIdentifier node) =>
      _getConstantValue(null);

  @override
  Object visitSimpleStringLiteral(SimpleStringLiteral node) => node.value;

  @override
  Object visitStringInterpolation(StringInterpolation node) {
    StringBuffer buffer = new StringBuffer();
    for (InterpolationElement element in node.elements) {
      Object value = element.accept(this);
      if (identical(value, NOT_A_CONSTANT)) {
        return value;
      }
      buffer.write(value);
    }
    return buffer.toString();
  }

  @override
  Object visitSymbolLiteral(SymbolLiteral node) {
    // TODO(brianwilkerson) This isn't optimal because a Symbol is not a String.
    StringBuffer buffer = new StringBuffer();
    for (Token component in node.components) {
      if (buffer.length > 0) {
        buffer.writeCharCode(0x2E);
      }
      buffer.write(component.lexeme);
    }
    return buffer.toString();
  }

  /**
   * Return the constant value of the static constant represented by the given
   * [element].
   */
  Object _getConstantValue(Element element) {
    // TODO(brianwilkerson) Implement this
    if (element is FieldElement) {
      FieldElement field = element;
      if (field.isStatic && field.isConst) {
        //field.getConstantValue();
      }
      //    } else if (element instanceof VariableElement) {
      //      VariableElement variable = (VariableElement) element;
      //      if (variable.isStatic() && variable.isConst()) {
      //        //variable.getConstantValue();
      //      }
    }
    return NOT_A_CONSTANT;
  }
}

/**
 * A recursive AST visitor that is used to run over [Expression]s to determine
 * whether the expression is composed by at least one deferred
 * [PrefixedIdentifier].
 *
 * See [PrefixedIdentifier.isDeferred].
 */
class DeferredLibraryReferenceDetector extends RecursiveAstVisitor<Object> {
  /**
   * A flag indicating whether an identifier from a deferred library has been
   * found.
   */
  bool _result = false;

  /**
   * Return `true` if the visitor found a [PrefixedIdentifier] that returned
   * `true` to the [PrefixedIdentifier.isDeferred] query.
   */
  bool get result => _result;

  @override
  Object visitPrefixedIdentifier(PrefixedIdentifier node) {
    if (!_result) {
      if (node.isDeferred) {
        _result = true;
      }
    }
    return null;
  }
}

/**
 * An object used to locate the [Element] associated with a given [AstNode].
 */
class ElementLocator {
  /**
   * Return the element associated with the given [node], or `null` if there is
   * no element associated with the node.
   */
  static Element locate(AstNode node) {
    if (node == null) {
      return null;
    }
    ElementLocator_ElementMapper mapper = new ElementLocator_ElementMapper();
    return node.accept(mapper);
  }
}

/**
 * Visitor that maps nodes to elements.
 */
class ElementLocator_ElementMapper extends GeneralizingAstVisitor<Element> {
  @override
  Element visitAnnotation(Annotation node) => node.element;

  @override
  Element visitAssignmentExpression(AssignmentExpression node) =>
      node.bestElement;

  @override
  Element visitBinaryExpression(BinaryExpression node) => node.bestElement;

  @override
  Element visitClassDeclaration(ClassDeclaration node) => node.element;

  @override
  Element visitCompilationUnit(CompilationUnit node) => node.element;

  @override
  Element visitConstructorDeclaration(ConstructorDeclaration node) =>
      node.element;

  @override
  Element visitFunctionDeclaration(FunctionDeclaration node) => node.element;

  @override
  Element visitIdentifier(Identifier node) {
    AstNode parent = node.parent;
    // Type name in Annotation
    if (parent is Annotation) {
      Annotation annotation = parent;
      if (identical(annotation.name, node) &&
          annotation.constructorName == null) {
        return annotation.element;
      }
    }
    // Extra work to map Constructor Declarations to their associated
    // Constructor Elements
    if (parent is ConstructorDeclaration) {
      Identifier returnType = parent.returnType;
      if (identical(returnType, node)) {
        SimpleIdentifier name = parent.name;
        if (name != null) {
          return name.bestElement;
        }
        Element element = node.bestElement;
        if (element is ClassElement) {
          return element.unnamedConstructor;
        }
      }
    }
    if (parent is LibraryIdentifier) {
      AstNode grandParent = parent.parent;
      if (grandParent is PartOfDirective) {
        Element element = grandParent.element;
        if (element is LibraryElement) {
          return element.definingCompilationUnit;
        }
      }
    }
    return node.bestElement;
  }

  @override
  Element visitImportDirective(ImportDirective node) => node.element;

  @override
  Element visitIndexExpression(IndexExpression node) => node.bestElement;

  @override
  Element visitInstanceCreationExpression(InstanceCreationExpression node) =>
      node.staticElement;

  @override
  Element visitLibraryDirective(LibraryDirective node) => node.element;

  @override
  Element visitMethodDeclaration(MethodDeclaration node) => node.element;

  @override
  Element visitMethodInvocation(MethodInvocation node) =>
      node.methodName.bestElement;

  @override
  Element visitPartOfDirective(PartOfDirective node) => node.element;

  @override
  Element visitPostfixExpression(PostfixExpression node) => node.bestElement;

  @override
  Element visitPrefixedIdentifier(PrefixedIdentifier node) => node.bestElement;

  @override
  Element visitPrefixExpression(PrefixExpression node) => node.bestElement;

  @override
  Element visitStringLiteral(StringLiteral node) {
    AstNode parent = node.parent;
    if (parent is UriBasedDirective) {
      return parent.uriElement;
    }
    return null;
  }

  @override
  Element visitVariableDeclaration(VariableDeclaration node) => node.element;
}

/**
 * An object that will clone any AST structure that it visits. The cloner will
 * clone the structure, replacing the specified ASTNode with a new ASTNode,
 * mapping the old token stream to a new token stream, and preserving resolution
 * results.
 */
class IncrementalAstCloner implements AstVisitor<AstNode> {
  /**
   * The node to be replaced during the cloning process.
   */
  final AstNode _oldNode;

  /**
   * The replacement node used during the cloning process.
   */
  final AstNode _newNode;

  /**
   * A mapping of old tokens to new tokens used during the cloning process.
   */
  final TokenMap _tokenMap;

  /**
   * Construct a new instance that will replace the [oldNode] with the [newNode]
   * in the process of cloning an existing AST structure. The [tokenMap] is a
   * mapping of old tokens to new tokens.
   */
  IncrementalAstCloner(this._oldNode, this._newNode, this._tokenMap);

  @override
  AdjacentStrings visitAdjacentStrings(AdjacentStrings node) =>
      new AdjacentStrings(_cloneNodeList(node.strings));

  @override
  Annotation visitAnnotation(Annotation node) {
    Annotation copy = new Annotation(
        _mapToken(node.atSign),
        _cloneNode(node.name),
        _mapToken(node.period),
        _cloneNode(node.constructorName),
        _cloneNode(node.arguments));
    copy.element = node.element;
    return copy;
  }

  @override
  ArgumentList visitArgumentList(ArgumentList node) => new ArgumentList(
      _mapToken(node.leftParenthesis),
      _cloneNodeList(node.arguments),
      _mapToken(node.rightParenthesis));

  @override
  AsExpression visitAsExpression(AsExpression node) {
    AsExpression copy = new AsExpression(_cloneNode(node.expression),
        _mapToken(node.asOperator), _cloneNode(node.type));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  AstNode visitAssertStatement(AssertStatement node) => new AssertStatement(
      _mapToken(node.assertKeyword),
      _mapToken(node.leftParenthesis),
      _cloneNode(node.condition),
      _mapToken(node.comma),
      _cloneNode(node.message),
      _mapToken(node.rightParenthesis),
      _mapToken(node.semicolon));

  @override
  AssignmentExpression visitAssignmentExpression(AssignmentExpression node) {
    AssignmentExpression copy = new AssignmentExpression(
        _cloneNode(node.leftHandSide),
        _mapToken(node.operator),
        _cloneNode(node.rightHandSide));
    copy.propagatedElement = node.propagatedElement;
    copy.propagatedType = node.propagatedType;
    copy.staticElement = node.staticElement;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  AwaitExpression visitAwaitExpression(AwaitExpression node) =>
      new AwaitExpression(
          _mapToken(node.awaitKeyword), _cloneNode(node.expression));

  @override
  BinaryExpression visitBinaryExpression(BinaryExpression node) {
    BinaryExpression copy = new BinaryExpression(_cloneNode(node.leftOperand),
        _mapToken(node.operator), _cloneNode(node.rightOperand));
    copy.propagatedElement = node.propagatedElement;
    copy.propagatedType = node.propagatedType;
    copy.staticElement = node.staticElement;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  Block visitBlock(Block node) => new Block(_mapToken(node.leftBracket),
      _cloneNodeList(node.statements), _mapToken(node.rightBracket));

  @override
  BlockFunctionBody visitBlockFunctionBody(BlockFunctionBody node) =>
      new BlockFunctionBody(_mapToken(node.keyword), _mapToken(node.star),
          _cloneNode(node.block));

  @override
  BooleanLiteral visitBooleanLiteral(BooleanLiteral node) {
    BooleanLiteral copy =
        new BooleanLiteral(_mapToken(node.literal), node.value);
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  BreakStatement visitBreakStatement(BreakStatement node) => new BreakStatement(
      _mapToken(node.breakKeyword),
      _cloneNode(node.label),
      _mapToken(node.semicolon));

  @override
  CascadeExpression visitCascadeExpression(CascadeExpression node) {
    CascadeExpression copy = new CascadeExpression(
        _cloneNode(node.target), _cloneNodeList(node.cascadeSections));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  CatchClause visitCatchClause(CatchClause node) => new CatchClause(
      _mapToken(node.onKeyword),
      _cloneNode(node.exceptionType),
      _mapToken(node.catchKeyword),
      _mapToken(node.leftParenthesis),
      _cloneNode(node.exceptionParameter),
      _mapToken(node.comma),
      _cloneNode(node.stackTraceParameter),
      _mapToken(node.rightParenthesis),
      _cloneNode(node.body));

  @override
  ClassDeclaration visitClassDeclaration(ClassDeclaration node) {
    ClassDeclaration copy = new ClassDeclaration(
        _cloneNode(node.documentationComment),
        _cloneNodeList(node.metadata),
        _mapToken(node.abstractKeyword),
        _mapToken(node.classKeyword),
        _cloneNode(node.name),
        _cloneNode(node.typeParameters),
        _cloneNode(node.extendsClause),
        _cloneNode(node.withClause),
        _cloneNode(node.implementsClause),
        _mapToken(node.leftBracket),
        _cloneNodeList(node.members),
        _mapToken(node.rightBracket));
    copy.nativeClause = _cloneNode(node.nativeClause);
    return copy;
  }

  @override
  ClassTypeAlias visitClassTypeAlias(ClassTypeAlias node) => new ClassTypeAlias(
      _cloneNode(node.documentationComment),
      _cloneNodeList(node.metadata),
      _mapToken(node.typedefKeyword),
      _cloneNode(node.name),
      _cloneNode(node.typeParameters),
      _mapToken(node.equals),
      _mapToken(node.abstractKeyword),
      _cloneNode(node.superclass),
      _cloneNode(node.withClause),
      _cloneNode(node.implementsClause),
      _mapToken(node.semicolon));

  @override
  Comment visitComment(Comment node) {
    if (node.isDocumentation) {
      return Comment.createDocumentationCommentWithReferences(
          _mapTokens(node.tokens), _cloneNodeList(node.references));
    } else if (node.isBlock) {
      return Comment.createBlockComment(_mapTokens(node.tokens));
    }
    return Comment.createEndOfLineComment(_mapTokens(node.tokens));
  }

  @override
  CommentReference visitCommentReference(CommentReference node) =>
      new CommentReference(
          _mapToken(node.newKeyword), _cloneNode(node.identifier));

  @override
  CompilationUnit visitCompilationUnit(CompilationUnit node) {
    CompilationUnit copy = new CompilationUnit(
        _mapToken(node.beginToken),
        _cloneNode(node.scriptTag),
        _cloneNodeList(node.directives),
        _cloneNodeList(node.declarations),
        _mapToken(node.endToken));
    copy.lineInfo = node.lineInfo;
    copy.element = node.element;
    return copy;
  }

  @override
  ConditionalExpression visitConditionalExpression(ConditionalExpression node) {
    ConditionalExpression copy = new ConditionalExpression(
        _cloneNode(node.condition),
        _mapToken(node.question),
        _cloneNode(node.thenExpression),
        _mapToken(node.colon),
        _cloneNode(node.elseExpression));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  Configuration visitConfiguration(Configuration node) => new Configuration(
      _mapToken(node.ifKeyword),
      _mapToken(node.leftParenthesis),
      _cloneNode(node.name),
      _mapToken(node.equalToken),
      _cloneNode(node.value),
      _mapToken(node.rightParenthesis),
      _cloneNode(node.libraryUri));

  @override
  ConstructorDeclaration visitConstructorDeclaration(
      ConstructorDeclaration node) {
    ConstructorDeclaration copy = new ConstructorDeclaration(
        _cloneNode(node.documentationComment),
        _cloneNodeList(node.metadata),
        _mapToken(node.externalKeyword),
        _mapToken(node.constKeyword),
        _mapToken(node.factoryKeyword),
        _cloneNode(node.returnType),
        _mapToken(node.period),
        _cloneNode(node.name),
        _cloneNode(node.parameters),
        _mapToken(node.separator),
        _cloneNodeList(node.initializers),
        _cloneNode(node.redirectedConstructor),
        _cloneNode(node.body));
    copy.element = node.element;
    return copy;
  }

  @override
  ConstructorFieldInitializer visitConstructorFieldInitializer(
          ConstructorFieldInitializer node) =>
      new ConstructorFieldInitializer(
          _mapToken(node.thisKeyword),
          _mapToken(node.period),
          _cloneNode(node.fieldName),
          _mapToken(node.equals),
          _cloneNode(node.expression));

  @override
  ConstructorName visitConstructorName(ConstructorName node) {
    ConstructorName copy = new ConstructorName(
        _cloneNode(node.type), _mapToken(node.period), _cloneNode(node.name));
    copy.staticElement = node.staticElement;
    return copy;
  }

  @override
  ContinueStatement visitContinueStatement(ContinueStatement node) =>
      new ContinueStatement(_mapToken(node.continueKeyword),
          _cloneNode(node.label), _mapToken(node.semicolon));

  @override
  DeclaredIdentifier visitDeclaredIdentifier(DeclaredIdentifier node) =>
      new DeclaredIdentifier(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _mapToken(node.keyword),
          _cloneNode(node.type),
          _cloneNode(node.identifier));

  @override
  DefaultFormalParameter visitDefaultFormalParameter(
          DefaultFormalParameter node) =>
      new DefaultFormalParameter(_cloneNode(node.parameter), node.kind,
          _mapToken(node.separator), _cloneNode(node.defaultValue));

  @override
  DoStatement visitDoStatement(DoStatement node) => new DoStatement(
      _mapToken(node.doKeyword),
      _cloneNode(node.body),
      _mapToken(node.whileKeyword),
      _mapToken(node.leftParenthesis),
      _cloneNode(node.condition),
      _mapToken(node.rightParenthesis),
      _mapToken(node.semicolon));

  @override
  DottedName visitDottedName(DottedName node) =>
      new DottedName(_cloneNodeList(node.components));

  @override
  DoubleLiteral visitDoubleLiteral(DoubleLiteral node) {
    DoubleLiteral copy = new DoubleLiteral(_mapToken(node.literal), node.value);
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  EmptyFunctionBody visitEmptyFunctionBody(EmptyFunctionBody node) =>
      new EmptyFunctionBody(_mapToken(node.semicolon));

  @override
  EmptyStatement visitEmptyStatement(EmptyStatement node) =>
      new EmptyStatement(_mapToken(node.semicolon));

  @override
  AstNode visitEnumConstantDeclaration(EnumConstantDeclaration node) =>
      new EnumConstantDeclaration(_cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata), _cloneNode(node.name));

  @override
  AstNode visitEnumDeclaration(EnumDeclaration node) => new EnumDeclaration(
      _cloneNode(node.documentationComment),
      _cloneNodeList(node.metadata),
      _mapToken(node.enumKeyword),
      _cloneNode(node.name),
      _mapToken(node.leftBracket),
      _cloneNodeList(node.constants),
      _mapToken(node.rightBracket));

  @override
  ExportDirective visitExportDirective(ExportDirective node) {
    ExportDirective copy = new ExportDirective(
        _cloneNode(node.documentationComment),
        _cloneNodeList(node.metadata),
        _mapToken(node.keyword),
        _cloneNode(node.uri),
        _cloneNodeList(node.configurations),
        _cloneNodeList(node.combinators),
        _mapToken(node.semicolon));
    copy.element = node.element;
    return copy;
  }

  @override
  ExpressionFunctionBody visitExpressionFunctionBody(
          ExpressionFunctionBody node) =>
      new ExpressionFunctionBody(
          _mapToken(node.keyword),
          _mapToken(node.functionDefinition),
          _cloneNode(node.expression),
          _mapToken(node.semicolon));

  @override
  ExpressionStatement visitExpressionStatement(ExpressionStatement node) =>
      new ExpressionStatement(
          _cloneNode(node.expression), _mapToken(node.semicolon));

  @override
  ExtendsClause visitExtendsClause(ExtendsClause node) => new ExtendsClause(
      _mapToken(node.extendsKeyword), _cloneNode(node.superclass));

  @override
  FieldDeclaration visitFieldDeclaration(FieldDeclaration node) =>
      new FieldDeclaration(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _mapToken(node.staticKeyword),
          _cloneNode(node.fields),
          _mapToken(node.semicolon));

  @override
  FieldFormalParameter visitFieldFormalParameter(FieldFormalParameter node) =>
      new FieldFormalParameter(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _mapToken(node.keyword),
          _cloneNode(node.type),
          _mapToken(node.thisKeyword),
          _mapToken(node.period),
          _cloneNode(node.identifier),
          _cloneNode(node.typeParameters),
          _cloneNode(node.parameters));

  @override
  ForEachStatement visitForEachStatement(ForEachStatement node) {
    DeclaredIdentifier loopVariable = node.loopVariable;
    if (loopVariable == null) {
      return new ForEachStatement.withReference(
          _mapToken(node.awaitKeyword),
          _mapToken(node.forKeyword),
          _mapToken(node.leftParenthesis),
          _cloneNode(node.identifier),
          _mapToken(node.inKeyword),
          _cloneNode(node.iterable),
          _mapToken(node.rightParenthesis),
          _cloneNode(node.body));
    }
    return new ForEachStatement.withDeclaration(
        _mapToken(node.awaitKeyword),
        _mapToken(node.forKeyword),
        _mapToken(node.leftParenthesis),
        _cloneNode(loopVariable),
        _mapToken(node.inKeyword),
        _cloneNode(node.iterable),
        _mapToken(node.rightParenthesis),
        _cloneNode(node.body));
  }

  @override
  FormalParameterList visitFormalParameterList(FormalParameterList node) =>
      new FormalParameterList(
          _mapToken(node.leftParenthesis),
          _cloneNodeList(node.parameters),
          _mapToken(node.leftDelimiter),
          _mapToken(node.rightDelimiter),
          _mapToken(node.rightParenthesis));

  @override
  ForStatement visitForStatement(ForStatement node) => new ForStatement(
      _mapToken(node.forKeyword),
      _mapToken(node.leftParenthesis),
      _cloneNode(node.variables),
      _cloneNode(node.initialization),
      _mapToken(node.leftSeparator),
      _cloneNode(node.condition),
      _mapToken(node.rightSeparator),
      _cloneNodeList(node.updaters),
      _mapToken(node.rightParenthesis),
      _cloneNode(node.body));

  @override
  FunctionDeclaration visitFunctionDeclaration(FunctionDeclaration node) =>
      new FunctionDeclaration(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _mapToken(node.externalKeyword),
          _cloneNode(node.returnType),
          _mapToken(node.propertyKeyword),
          _cloneNode(node.name),
          _cloneNode(node.functionExpression));

  @override
  FunctionDeclarationStatement visitFunctionDeclarationStatement(
          FunctionDeclarationStatement node) =>
      new FunctionDeclarationStatement(_cloneNode(node.functionDeclaration));

  @override
  FunctionExpression visitFunctionExpression(FunctionExpression node) {
    FunctionExpression copy = new FunctionExpression(
        _cloneNode(node.typeParameters),
        _cloneNode(node.parameters),
        _cloneNode(node.body));
    copy.element = node.element;
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  FunctionExpressionInvocation visitFunctionExpressionInvocation(
      FunctionExpressionInvocation node) {
    FunctionExpressionInvocation copy = new FunctionExpressionInvocation(
        _cloneNode(node.function),
        _cloneNode(node.typeArguments),
        _cloneNode(node.argumentList));
    copy.propagatedElement = node.propagatedElement;
    copy.propagatedType = node.propagatedType;
    copy.staticElement = node.staticElement;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  FunctionTypeAlias visitFunctionTypeAlias(FunctionTypeAlias node) =>
      new FunctionTypeAlias(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _mapToken(node.typedefKeyword),
          _cloneNode(node.returnType),
          _cloneNode(node.name),
          _cloneNode(node.typeParameters),
          _cloneNode(node.parameters),
          _mapToken(node.semicolon));

  @override
  FunctionTypedFormalParameter visitFunctionTypedFormalParameter(
          FunctionTypedFormalParameter node) =>
      new FunctionTypedFormalParameter(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _cloneNode(node.returnType),
          _cloneNode(node.identifier),
          _cloneNode(node.typeParameters),
          _cloneNode(node.parameters));

  @override
  HideCombinator visitHideCombinator(HideCombinator node) => new HideCombinator(
      _mapToken(node.keyword), _cloneNodeList(node.hiddenNames));

  @override
  IfStatement visitIfStatement(IfStatement node) => new IfStatement(
      _mapToken(node.ifKeyword),
      _mapToken(node.leftParenthesis),
      _cloneNode(node.condition),
      _mapToken(node.rightParenthesis),
      _cloneNode(node.thenStatement),
      _mapToken(node.elseKeyword),
      _cloneNode(node.elseStatement));

  @override
  ImplementsClause visitImplementsClause(ImplementsClause node) =>
      new ImplementsClause(
          _mapToken(node.implementsKeyword), _cloneNodeList(node.interfaces));

  @override
  ImportDirective visitImportDirective(ImportDirective node) =>
      new ImportDirective(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _mapToken(node.keyword),
          _cloneNode(node.uri),
          _cloneNodeList(node.configurations),
          _mapToken(node.deferredKeyword),
          _mapToken(node.asKeyword),
          _cloneNode(node.prefix),
          _cloneNodeList(node.combinators),
          _mapToken(node.semicolon));

  @override
  IndexExpression visitIndexExpression(IndexExpression node) {
    Token period = _mapToken(node.period);
    IndexExpression copy;
    if (period == null) {
      copy = new IndexExpression.forTarget(
          _cloneNode(node.target),
          _mapToken(node.leftBracket),
          _cloneNode(node.index),
          _mapToken(node.rightBracket));
    } else {
      copy = new IndexExpression.forCascade(period, _mapToken(node.leftBracket),
          _cloneNode(node.index), _mapToken(node.rightBracket));
    }
    copy.auxiliaryElements = node.auxiliaryElements;
    copy.propagatedElement = node.propagatedElement;
    copy.propagatedType = node.propagatedType;
    copy.staticElement = node.staticElement;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  InstanceCreationExpression visitInstanceCreationExpression(
      InstanceCreationExpression node) {
    InstanceCreationExpression copy = new InstanceCreationExpression(
        _mapToken(node.keyword),
        _cloneNode(node.constructorName),
        _cloneNode(node.argumentList));
    copy.propagatedType = node.propagatedType;
    copy.staticElement = node.staticElement;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  IntegerLiteral visitIntegerLiteral(IntegerLiteral node) {
    IntegerLiteral copy =
        new IntegerLiteral(_mapToken(node.literal), node.value);
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  InterpolationExpression visitInterpolationExpression(
          InterpolationExpression node) =>
      new InterpolationExpression(_mapToken(node.leftBracket),
          _cloneNode(node.expression), _mapToken(node.rightBracket));

  @override
  InterpolationString visitInterpolationString(InterpolationString node) =>
      new InterpolationString(_mapToken(node.contents), node.value);

  @override
  IsExpression visitIsExpression(IsExpression node) {
    IsExpression copy = new IsExpression(
        _cloneNode(node.expression),
        _mapToken(node.isOperator),
        _mapToken(node.notOperator),
        _cloneNode(node.type));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  Label visitLabel(Label node) =>
      new Label(_cloneNode(node.label), _mapToken(node.colon));

  @override
  LabeledStatement visitLabeledStatement(LabeledStatement node) =>
      new LabeledStatement(
          _cloneNodeList(node.labels), _cloneNode(node.statement));

  @override
  LibraryDirective visitLibraryDirective(LibraryDirective node) =>
      new LibraryDirective(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _mapToken(node.libraryKeyword),
          _cloneNode(node.name),
          _mapToken(node.semicolon));

  @override
  LibraryIdentifier visitLibraryIdentifier(LibraryIdentifier node) {
    LibraryIdentifier copy =
        new LibraryIdentifier(_cloneNodeList(node.components));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  ListLiteral visitListLiteral(ListLiteral node) {
    ListLiteral copy = new ListLiteral(
        _mapToken(node.constKeyword),
        _cloneNode(node.typeArguments),
        _mapToken(node.leftBracket),
        _cloneNodeList(node.elements),
        _mapToken(node.rightBracket));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  MapLiteral visitMapLiteral(MapLiteral node) {
    MapLiteral copy = new MapLiteral(
        _mapToken(node.constKeyword),
        _cloneNode(node.typeArguments),
        _mapToken(node.leftBracket),
        _cloneNodeList(node.entries),
        _mapToken(node.rightBracket));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  MapLiteralEntry visitMapLiteralEntry(MapLiteralEntry node) =>
      new MapLiteralEntry(_cloneNode(node.key), _mapToken(node.separator),
          _cloneNode(node.value));

  @override
  MethodDeclaration visitMethodDeclaration(MethodDeclaration node) =>
      new MethodDeclaration(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _mapToken(node.externalKeyword),
          _mapToken(node.modifierKeyword),
          _cloneNode(node.returnType),
          _mapToken(node.propertyKeyword),
          _mapToken(node.operatorKeyword),
          _cloneNode(node.name),
          _cloneNode(node.typeParameters),
          _cloneNode(node.parameters),
          _cloneNode(node.body));

  @override
  MethodInvocation visitMethodInvocation(MethodInvocation node) {
    MethodInvocation copy = new MethodInvocation(
        _cloneNode(node.target),
        _mapToken(node.operator),
        _cloneNode(node.methodName),
        _cloneNode(node.typeArguments),
        _cloneNode(node.argumentList));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  NamedExpression visitNamedExpression(NamedExpression node) {
    NamedExpression copy =
        new NamedExpression(_cloneNode(node.name), _cloneNode(node.expression));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  AstNode visitNativeClause(NativeClause node) =>
      new NativeClause(_mapToken(node.nativeKeyword), _cloneNode(node.name));

  @override
  NativeFunctionBody visitNativeFunctionBody(NativeFunctionBody node) =>
      new NativeFunctionBody(_mapToken(node.nativeKeyword),
          _cloneNode(node.stringLiteral), _mapToken(node.semicolon));

  @override
  NullLiteral visitNullLiteral(NullLiteral node) {
    NullLiteral copy = new NullLiteral(_mapToken(node.literal));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  ParenthesizedExpression visitParenthesizedExpression(
      ParenthesizedExpression node) {
    ParenthesizedExpression copy = new ParenthesizedExpression(
        _mapToken(node.leftParenthesis),
        _cloneNode(node.expression),
        _mapToken(node.rightParenthesis));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  PartDirective visitPartDirective(PartDirective node) {
    PartDirective copy = new PartDirective(
        _cloneNode(node.documentationComment),
        _cloneNodeList(node.metadata),
        _mapToken(node.partKeyword),
        _cloneNode(node.uri),
        _mapToken(node.semicolon));
    copy.element = node.element;
    return copy;
  }

  @override
  PartOfDirective visitPartOfDirective(PartOfDirective node) {
    PartOfDirective copy = new PartOfDirective(
        _cloneNode(node.documentationComment),
        _cloneNodeList(node.metadata),
        _mapToken(node.partKeyword),
        _mapToken(node.ofKeyword),
        _cloneNode(node.libraryName),
        _mapToken(node.semicolon));
    copy.element = node.element;
    return copy;
  }

  @override
  PostfixExpression visitPostfixExpression(PostfixExpression node) {
    PostfixExpression copy = new PostfixExpression(
        _cloneNode(node.operand), _mapToken(node.operator));
    copy.propagatedElement = node.propagatedElement;
    copy.propagatedType = node.propagatedType;
    copy.staticElement = node.staticElement;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  PrefixedIdentifier visitPrefixedIdentifier(PrefixedIdentifier node) {
    PrefixedIdentifier copy = new PrefixedIdentifier(_cloneNode(node.prefix),
        _mapToken(node.period), _cloneNode(node.identifier));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  PrefixExpression visitPrefixExpression(PrefixExpression node) {
    PrefixExpression copy = new PrefixExpression(
        _mapToken(node.operator), _cloneNode(node.operand));
    copy.propagatedElement = node.propagatedElement;
    copy.propagatedType = node.propagatedType;
    copy.staticElement = node.staticElement;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  PropertyAccess visitPropertyAccess(PropertyAccess node) {
    PropertyAccess copy = new PropertyAccess(_cloneNode(node.target),
        _mapToken(node.operator), _cloneNode(node.propertyName));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  RedirectingConstructorInvocation visitRedirectingConstructorInvocation(
      RedirectingConstructorInvocation node) {
    RedirectingConstructorInvocation copy =
        new RedirectingConstructorInvocation(
            _mapToken(node.thisKeyword),
            _mapToken(node.period),
            _cloneNode(node.constructorName),
            _cloneNode(node.argumentList));
    copy.staticElement = node.staticElement;
    return copy;
  }

  @override
  RethrowExpression visitRethrowExpression(RethrowExpression node) {
    RethrowExpression copy =
        new RethrowExpression(_mapToken(node.rethrowKeyword));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  ReturnStatement visitReturnStatement(ReturnStatement node) =>
      new ReturnStatement(_mapToken(node.returnKeyword),
          _cloneNode(node.expression), _mapToken(node.semicolon));

  @override
  ScriptTag visitScriptTag(ScriptTag node) =>
      new ScriptTag(_mapToken(node.scriptTag));

  @override
  ShowCombinator visitShowCombinator(ShowCombinator node) => new ShowCombinator(
      _mapToken(node.keyword), _cloneNodeList(node.shownNames));

  @override
  SimpleFormalParameter visitSimpleFormalParameter(
          SimpleFormalParameter node) =>
      new SimpleFormalParameter(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _mapToken(node.keyword),
          _cloneNode(node.type),
          _cloneNode(node.identifier));

  @override
  SimpleIdentifier visitSimpleIdentifier(SimpleIdentifier node) {
    Token mappedToken = _mapToken(node.token);
    if (mappedToken == null) {
      // This only happens for SimpleIdentifiers created by the parser as part
      // of scanning documentation comments (the tokens for those identifiers
      // are not in the original token stream and hence do not get copied).
      // This extra check can be removed if the scanner is changed to scan
      // documentation comments for the parser.
      mappedToken = node.token;
    }
    SimpleIdentifier copy = new SimpleIdentifier(mappedToken);
    copy.auxiliaryElements = node.auxiliaryElements;
    copy.propagatedElement = node.propagatedElement;
    copy.propagatedType = node.propagatedType;
    copy.staticElement = node.staticElement;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  SimpleStringLiteral visitSimpleStringLiteral(SimpleStringLiteral node) {
    SimpleStringLiteral copy =
        new SimpleStringLiteral(_mapToken(node.literal), node.value);
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  StringInterpolation visitStringInterpolation(StringInterpolation node) {
    StringInterpolation copy =
        new StringInterpolation(_cloneNodeList(node.elements));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  SuperConstructorInvocation visitSuperConstructorInvocation(
      SuperConstructorInvocation node) {
    SuperConstructorInvocation copy = new SuperConstructorInvocation(
        _mapToken(node.superKeyword),
        _mapToken(node.period),
        _cloneNode(node.constructorName),
        _cloneNode(node.argumentList));
    copy.staticElement = node.staticElement;
    return copy;
  }

  @override
  SuperExpression visitSuperExpression(SuperExpression node) {
    SuperExpression copy = new SuperExpression(_mapToken(node.superKeyword));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  SwitchCase visitSwitchCase(SwitchCase node) => new SwitchCase(
      _cloneNodeList(node.labels),
      _mapToken(node.keyword),
      _cloneNode(node.expression),
      _mapToken(node.colon),
      _cloneNodeList(node.statements));

  @override
  SwitchDefault visitSwitchDefault(SwitchDefault node) => new SwitchDefault(
      _cloneNodeList(node.labels),
      _mapToken(node.keyword),
      _mapToken(node.colon),
      _cloneNodeList(node.statements));

  @override
  SwitchStatement visitSwitchStatement(SwitchStatement node) =>
      new SwitchStatement(
          _mapToken(node.switchKeyword),
          _mapToken(node.leftParenthesis),
          _cloneNode(node.expression),
          _mapToken(node.rightParenthesis),
          _mapToken(node.leftBracket),
          _cloneNodeList(node.members),
          _mapToken(node.rightBracket));

  @override
  AstNode visitSymbolLiteral(SymbolLiteral node) {
    SymbolLiteral copy = new SymbolLiteral(
        _mapToken(node.poundSign), _mapTokens(node.components));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  ThisExpression visitThisExpression(ThisExpression node) {
    ThisExpression copy = new ThisExpression(_mapToken(node.thisKeyword));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  ThrowExpression visitThrowExpression(ThrowExpression node) {
    ThrowExpression copy = new ThrowExpression(
        _mapToken(node.throwKeyword), _cloneNode(node.expression));
    copy.propagatedType = node.propagatedType;
    copy.staticType = node.staticType;
    return copy;
  }

  @override
  TopLevelVariableDeclaration visitTopLevelVariableDeclaration(
          TopLevelVariableDeclaration node) =>
      new TopLevelVariableDeclaration(
          _cloneNode(node.documentationComment),
          _cloneNodeList(node.metadata),
          _cloneNode(node.variables),
          _mapToken(node.semicolon));

  @override
  TryStatement visitTryStatement(TryStatement node) => new TryStatement(
      _mapToken(node.tryKeyword),
      _cloneNode(node.body),
      _cloneNodeList(node.catchClauses),
      _mapToken(node.finallyKeyword),
      _cloneNode(node.finallyBlock));

  @override
  TypeArgumentList visitTypeArgumentList(TypeArgumentList node) =>
      new TypeArgumentList(_mapToken(node.leftBracket),
          _cloneNodeList(node.arguments), _mapToken(node.rightBracket));

  @override
  TypeName visitTypeName(TypeName node) {
    TypeName copy =
        new TypeName(_cloneNode(node.name), _cloneNode(node.typeArguments));
    copy.type = node.type;
    return copy;
  }

  @override
  TypeParameter visitTypeParameter(TypeParameter node) => new TypeParameter(
      _cloneNode(node.documentationComment),
      _cloneNodeList(node.metadata),
      _cloneNode(node.name),
      _mapToken(node.extendsKeyword),
      _cloneNode(node.bound));

  @override
  TypeParameterList visitTypeParameterList(TypeParameterList node) =>
      new TypeParameterList(_mapToken(node.leftBracket),
          _cloneNodeList(node.typeParameters), _mapToken(node.rightBracket));

  @override
  VariableDeclaration visitVariableDeclaration(VariableDeclaration node) =>
      new VariableDeclaration(_cloneNode(node.name), _mapToken(node.equals),
          _cloneNode(node.initializer));

  @override
  VariableDeclarationList visitVariableDeclarationList(
          VariableDeclarationList node) =>
      new VariableDeclarationList(
          null,
          _cloneNodeList(node.metadata),
          _mapToken(node.keyword),
          _cloneNode(node.type),
          _cloneNodeList(node.variables));

  @override
  VariableDeclarationStatement visitVariableDeclarationStatement(
          VariableDeclarationStatement node) =>
      new VariableDeclarationStatement(
          _cloneNode(node.variables), _mapToken(node.semicolon));

  @override
  WhileStatement visitWhileStatement(WhileStatement node) => new WhileStatement(
      _mapToken(node.whileKeyword),
      _mapToken(node.leftParenthesis),
      _cloneNode(node.condition),
      _mapToken(node.rightParenthesis),
      _cloneNode(node.body));

  @override
  WithClause visitWithClause(WithClause node) => new WithClause(
      _mapToken(node.withKeyword), _cloneNodeList(node.mixinTypes));

  @override
  YieldStatement visitYieldStatement(YieldStatement node) => new YieldStatement(
      _mapToken(node.yieldKeyword),
      _mapToken(node.star),
      _cloneNode(node.expression),
      _mapToken(node.semicolon));

  AstNode _cloneNode(AstNode node) {
    if (node == null) {
      return null;
    }
    if (identical(node, _oldNode)) {
      return _newNode;
    }
    return node.accept(this) as AstNode;
  }

  List _cloneNodeList(NodeList nodes) {
    List clonedNodes = new List();
    for (AstNode node in nodes) {
      clonedNodes.add(_cloneNode(node));
    }
    return clonedNodes;
  }

  Token _mapToken(Token oldToken) {
    if (oldToken == null) {
      return null;
    }
    return _tokenMap.get(oldToken);
  }

  List<Token> _mapTokens(List<Token> oldTokens) {
    List<Token> newTokens = new List<Token>(oldTokens.length);
    for (int index = 0; index < newTokens.length; index++) {
      newTokens[index] = _mapToken(oldTokens[index]);
    }
    return newTokens;
  }
}

/**
 * An object used to locate the [AstNode] associated with a source range, given
 * the AST structure built from the source. More specifically, they will return
 * the [AstNode] with the shortest length whose source range completely
 * encompasses the specified range.
 */
class NodeLocator extends UnifyingAstVisitor<Object> {
  /**
   * The start offset of the range used to identify the node.
   */
  int _startOffset = 0;

  /**
   * The end offset of the range used to identify the node.
   */
  int _endOffset = 0;

  /**
   * The element that was found that corresponds to the given source range, or
   * `null` if there is no such element.
   */
  AstNode _foundNode;

  /**
   * Initialize a newly created locator to locate an [AstNode] by locating the
   * node within an AST structure that corresponds to the given range of
   * characters (between the [startOffset] and [endOffset] in the source.
   */
  NodeLocator(int startOffset, [int endOffset])
      : this._startOffset = startOffset,
        this._endOffset = endOffset == null ? startOffset : endOffset;

  /**
   * Return the node that was found that corresponds to the given source range
   * or `null` if there is no such node.
   */
  AstNode get foundNode => _foundNode;

  /**
   * Search within the given AST [node] for an identifier representing an
   * element in the specified source range. Return the element that was found,
   * or `null` if no element was found.
   */
  AstNode searchWithin(AstNode node) {
    if (node == null) {
      return null;
    }
    try {
      node.accept(this);
    } on NodeLocator_NodeFoundException {
      // A node with the right source position was found.
    } catch (exception, stackTrace) {
      AnalysisEngine.instance.logger.logInformation(
          "Unable to locate element at offset ($_startOffset - $_endOffset)",
          new CaughtException(exception, stackTrace));
      return null;
    }
    return _foundNode;
  }

  @override
  Object visitNode(AstNode node) {
    Token beginToken = node.beginToken;
    Token endToken = node.endToken;
    // Don't include synthetic tokens.
    while (endToken != beginToken) {
      if (endToken.type == TokenType.EOF || !endToken.isSynthetic) {
        break;
      }
      endToken = endToken.previous;
    }
    int end = endToken.end;
    int start = node.offset;
    if (end < _startOffset) {
      return null;
    }
    if (start > _endOffset) {
      return null;
    }
    try {
      node.visitChildren(this);
    } on NodeLocator_NodeFoundException {
      rethrow;
    } catch (exception, stackTrace) {
      // Ignore the exception and proceed in order to visit the rest of the
      // structure.
      AnalysisEngine.instance.logger.logInformation(
          "Exception caught while traversing an AST structure.",
          new CaughtException(exception, stackTrace));
    }
    if (start <= _startOffset && _endOffset <= end) {
      _foundNode = node;
      throw new NodeLocator_NodeFoundException();
    }
    return null;
  }
}

/**
 * An object used to locate the [AstNode] associated with a source range.
 * More specifically, they will return the deepest [AstNode] which completely
 * encompasses the specified range.
 */
class NodeLocator2 extends UnifyingAstVisitor<Object> {
  /**
   * The inclusive start offset of the range used to identify the node.
   */
  int _startOffset = 0;

  /**
   * The inclusive end offset of the range used to identify the node.
   */
  int _endOffset = 0;

  /**
   * The found node or `null` if there is no such node.
   */
  AstNode _foundNode;

  /**
   * Initialize a newly created locator to locate the deepest [AstNode] for
   * which `node.offset <= [startOffset]` and `[endOffset] < node.end`.
   *
   * If [endOffset] is not provided, then it is considered the same as the
   * given [startOffset].
   */
  NodeLocator2(int startOffset, [int endOffset])
      : this._startOffset = startOffset,
        this._endOffset = endOffset == null ? startOffset : endOffset;

  /**
   * Search within the given AST [node] and return the node that was found,
   * or `null` if no node was found.
   */
  AstNode searchWithin(AstNode node) {
    if (node == null) {
      return null;
    }
    try {
      node.accept(this);
    } on NodeLocator_NodeFoundException {} catch (exception, stackTrace) {
      AnalysisEngine.instance.logger.logInformation(
          "Unable to locate element at offset ($_startOffset - $_endOffset)",
          new CaughtException(exception, stackTrace));
      return null;
    }
    return _foundNode;
  }

  @override
  Object visitNode(AstNode node) {
    Token beginToken = node.beginToken;
    Token endToken = node.endToken;
    // Don't include synthetic tokens.
    while (endToken != beginToken) {
      if (endToken.type == TokenType.EOF || !endToken.isSynthetic) {
        break;
      }
      endToken = endToken.previous;
    }
    int end = endToken.end;
    int start = node.offset;
    if (end <= _startOffset) {
      return null;
    }
    if (start > _endOffset) {
      return null;
    }
    try {
      node.visitChildren(this);
    } on NodeLocator_NodeFoundException {
      rethrow;
    } catch (exception, stackTrace) {
      // Ignore the exception and proceed in order to visit the rest of the
      // structure.
      AnalysisEngine.instance.logger.logInformation(
          "Exception caught while traversing an AST structure.",
          new CaughtException(exception, stackTrace));
    }
    if (start <= _startOffset && _endOffset < end) {
      _foundNode = node;
      throw new NodeLocator_NodeFoundException();
    }
    return null;
  }
}

/**
 * An exception used by [NodeLocator] to cancel visiting after a node has been
 * found.
 */
class NodeLocator_NodeFoundException extends RuntimeException {}

/**
 * An object that will replace one child node in an AST node with another node.
 */
class NodeReplacer implements AstVisitor<bool> {
  /**
   * The node being replaced.
   */
  final AstNode _oldNode;

  /**
   * The node that is replacing the old node.
   */
  final AstNode _newNode;

  /**
   * Initialize a newly created node locator to replace the [_oldNode] with the
   * [_newNode].
   */
  NodeReplacer(this._oldNode, this._newNode);

  @override
  bool visitAdjacentStrings(AdjacentStrings node) {
    if (_replaceInList(node.strings)) {
      return true;
    }
    return visitNode(node);
  }

  bool visitAnnotatedNode(AnnotatedNode node) {
    if (identical(node.documentationComment, _oldNode)) {
      node.documentationComment = _newNode as Comment;
      return true;
    } else if (_replaceInList(node.metadata)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitAnnotation(Annotation node) {
    if (identical(node.arguments, _oldNode)) {
      node.arguments = _newNode as ArgumentList;
      return true;
    } else if (identical(node.constructorName, _oldNode)) {
      node.constructorName = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.name, _oldNode)) {
      node.name = _newNode as Identifier;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitArgumentList(ArgumentList node) {
    if (_replaceInList(node.arguments)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitAsExpression(AsExpression node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    } else if (identical(node.type, _oldNode)) {
      node.type = _newNode as TypeName;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitAssertStatement(AssertStatement node) {
    if (identical(node.condition, _oldNode)) {
      node.condition = _newNode as Expression;
      return true;
    }
    if (identical(node.message, _oldNode)) {
      node.message = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitAssignmentExpression(AssignmentExpression node) {
    if (identical(node.leftHandSide, _oldNode)) {
      node.leftHandSide = _newNode as Expression;
      return true;
    } else if (identical(node.rightHandSide, _oldNode)) {
      node.rightHandSide = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitAwaitExpression(AwaitExpression node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitBinaryExpression(BinaryExpression node) {
    if (identical(node.leftOperand, _oldNode)) {
      node.leftOperand = _newNode as Expression;
      return true;
    } else if (identical(node.rightOperand, _oldNode)) {
      node.rightOperand = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitBlock(Block node) {
    if (_replaceInList(node.statements)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitBlockFunctionBody(BlockFunctionBody node) {
    if (identical(node.block, _oldNode)) {
      node.block = _newNode as Block;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitBooleanLiteral(BooleanLiteral node) => visitNode(node);

  @override
  bool visitBreakStatement(BreakStatement node) {
    if (identical(node.label, _oldNode)) {
      node.label = _newNode as SimpleIdentifier;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitCascadeExpression(CascadeExpression node) {
    if (identical(node.target, _oldNode)) {
      node.target = _newNode as Expression;
      return true;
    } else if (_replaceInList(node.cascadeSections)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitCatchClause(CatchClause node) {
    if (identical(node.exceptionType, _oldNode)) {
      node.exceptionType = _newNode as TypeName;
      return true;
    } else if (identical(node.exceptionParameter, _oldNode)) {
      node.exceptionParameter = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.stackTraceParameter, _oldNode)) {
      node.stackTraceParameter = _newNode as SimpleIdentifier;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitClassDeclaration(ClassDeclaration node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.typeParameters, _oldNode)) {
      node.typeParameters = _newNode as TypeParameterList;
      return true;
    } else if (identical(node.extendsClause, _oldNode)) {
      node.extendsClause = _newNode as ExtendsClause;
      return true;
    } else if (identical(node.withClause, _oldNode)) {
      node.withClause = _newNode as WithClause;
      return true;
    } else if (identical(node.implementsClause, _oldNode)) {
      node.implementsClause = _newNode as ImplementsClause;
      return true;
    } else if (identical(node.nativeClause, _oldNode)) {
      node.nativeClause = _newNode as NativeClause;
      return true;
    } else if (_replaceInList(node.members)) {
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitClassTypeAlias(ClassTypeAlias node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.typeParameters, _oldNode)) {
      node.typeParameters = _newNode as TypeParameterList;
      return true;
    } else if (identical(node.superclass, _oldNode)) {
      node.superclass = _newNode as TypeName;
      return true;
    } else if (identical(node.withClause, _oldNode)) {
      node.withClause = _newNode as WithClause;
      return true;
    } else if (identical(node.implementsClause, _oldNode)) {
      node.implementsClause = _newNode as ImplementsClause;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitComment(Comment node) {
    if (_replaceInList(node.references)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitCommentReference(CommentReference node) {
    if (identical(node.identifier, _oldNode)) {
      node.identifier = _newNode as Identifier;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitCompilationUnit(CompilationUnit node) {
    if (identical(node.scriptTag, _oldNode)) {
      node.scriptTag = _newNode as ScriptTag;
      return true;
    } else if (_replaceInList(node.directives)) {
      return true;
    } else if (_replaceInList(node.declarations)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitConditionalExpression(ConditionalExpression node) {
    if (identical(node.condition, _oldNode)) {
      node.condition = _newNode as Expression;
      return true;
    } else if (identical(node.thenExpression, _oldNode)) {
      node.thenExpression = _newNode as Expression;
      return true;
    } else if (identical(node.elseExpression, _oldNode)) {
      node.elseExpression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitConfiguration(Configuration node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as DottedName;
      return true;
    } else if (identical(node.value, _oldNode)) {
      node.value = _newNode as StringLiteral;
      return true;
    } else if (identical(node.libraryUri, _oldNode)) {
      node.libraryUri = _newNode as StringLiteral;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitConstructorDeclaration(ConstructorDeclaration node) {
    if (identical(node.returnType, _oldNode)) {
      node.returnType = _newNode as Identifier;
      return true;
    } else if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.parameters, _oldNode)) {
      node.parameters = _newNode as FormalParameterList;
      return true;
    } else if (identical(node.redirectedConstructor, _oldNode)) {
      node.redirectedConstructor = _newNode as ConstructorName;
      return true;
    } else if (identical(node.body, _oldNode)) {
      node.body = _newNode as FunctionBody;
      return true;
    } else if (_replaceInList(node.initializers)) {
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
    if (identical(node.fieldName, _oldNode)) {
      node.fieldName = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitConstructorName(ConstructorName node) {
    if (identical(node.type, _oldNode)) {
      node.type = _newNode as TypeName;
      return true;
    } else if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitContinueStatement(ContinueStatement node) {
    if (identical(node.label, _oldNode)) {
      node.label = _newNode as SimpleIdentifier;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitDeclaredIdentifier(DeclaredIdentifier node) {
    if (identical(node.type, _oldNode)) {
      node.type = _newNode as TypeName;
      return true;
    } else if (identical(node.identifier, _oldNode)) {
      node.identifier = _newNode as SimpleIdentifier;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitDefaultFormalParameter(DefaultFormalParameter node) {
    if (identical(node.parameter, _oldNode)) {
      node.parameter = _newNode as NormalFormalParameter;
      return true;
    } else if (identical(node.defaultValue, _oldNode)) {
      node.defaultValue = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitDoStatement(DoStatement node) {
    if (identical(node.body, _oldNode)) {
      node.body = _newNode as Statement;
      return true;
    } else if (identical(node.condition, _oldNode)) {
      node.condition = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitDottedName(DottedName node) {
    if (_replaceInList(node.components)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitDoubleLiteral(DoubleLiteral node) => visitNode(node);

  @override
  bool visitEmptyFunctionBody(EmptyFunctionBody node) => visitNode(node);

  @override
  bool visitEmptyStatement(EmptyStatement node) => visitNode(node);

  @override
  bool visitEnumConstantDeclaration(EnumConstantDeclaration node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitEnumDeclaration(EnumDeclaration node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    } else if (_replaceInList(node.constants)) {
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitExportDirective(ExportDirective node) =>
      visitNamespaceDirective(node);

  @override
  bool visitExpressionFunctionBody(ExpressionFunctionBody node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitExpressionStatement(ExpressionStatement node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitExtendsClause(ExtendsClause node) {
    if (identical(node.superclass, _oldNode)) {
      node.superclass = _newNode as TypeName;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitFieldDeclaration(FieldDeclaration node) {
    if (identical(node.fields, _oldNode)) {
      node.fields = _newNode as VariableDeclarationList;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitFieldFormalParameter(FieldFormalParameter node) {
    if (identical(node.type, _oldNode)) {
      node.type = _newNode as TypeName;
      return true;
    } else if (identical(node.parameters, _oldNode)) {
      node.parameters = _newNode as FormalParameterList;
      return true;
    }
    return visitNormalFormalParameter(node);
  }

  @override
  bool visitForEachStatement(ForEachStatement node) {
    if (identical(node.loopVariable, _oldNode)) {
      node.loopVariable = _newNode as DeclaredIdentifier;
      return true;
    } else if (identical(node.identifier, _oldNode)) {
      node.identifier = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.iterable, _oldNode)) {
      node.iterable = _newNode as Expression;
      return true;
    } else if (identical(node.body, _oldNode)) {
      node.body = _newNode as Statement;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitFormalParameterList(FormalParameterList node) {
    if (_replaceInList(node.parameters)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitForStatement(ForStatement node) {
    if (identical(node.variables, _oldNode)) {
      node.variables = _newNode as VariableDeclarationList;
      return true;
    } else if (identical(node.initialization, _oldNode)) {
      node.initialization = _newNode as Expression;
      return true;
    } else if (identical(node.condition, _oldNode)) {
      node.condition = _newNode as Expression;
      return true;
    } else if (identical(node.body, _oldNode)) {
      node.body = _newNode as Statement;
      return true;
    } else if (_replaceInList(node.updaters)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitFunctionDeclaration(FunctionDeclaration node) {
    if (identical(node.returnType, _oldNode)) {
      node.returnType = _newNode as TypeName;
      return true;
    } else if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.functionExpression, _oldNode)) {
      node.functionExpression = _newNode as FunctionExpression;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitFunctionDeclarationStatement(FunctionDeclarationStatement node) {
    if (identical(node.functionDeclaration, _oldNode)) {
      node.functionDeclaration = _newNode as FunctionDeclaration;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitFunctionExpression(FunctionExpression node) {
    if (identical(node.parameters, _oldNode)) {
      node.parameters = _newNode as FormalParameterList;
      return true;
    } else if (identical(node.body, _oldNode)) {
      node.body = _newNode as FunctionBody;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitFunctionExpressionInvocation(FunctionExpressionInvocation node) {
    if (identical(node.function, _oldNode)) {
      node.function = _newNode as Expression;
      return true;
    } else if (identical(node.argumentList, _oldNode)) {
      node.argumentList = _newNode as ArgumentList;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitFunctionTypeAlias(FunctionTypeAlias node) {
    if (identical(node.returnType, _oldNode)) {
      node.returnType = _newNode as TypeName;
      return true;
    } else if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.typeParameters, _oldNode)) {
      node.typeParameters = _newNode as TypeParameterList;
      return true;
    } else if (identical(node.parameters, _oldNode)) {
      node.parameters = _newNode as FormalParameterList;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
    if (identical(node.returnType, _oldNode)) {
      node.returnType = _newNode as TypeName;
      return true;
    } else if (identical(node.parameters, _oldNode)) {
      node.parameters = _newNode as FormalParameterList;
      return true;
    }
    return visitNormalFormalParameter(node);
  }

  @override
  bool visitHideCombinator(HideCombinator node) {
    if (_replaceInList(node.hiddenNames)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitIfStatement(IfStatement node) {
    if (identical(node.condition, _oldNode)) {
      node.condition = _newNode as Expression;
      return true;
    } else if (identical(node.thenStatement, _oldNode)) {
      node.thenStatement = _newNode as Statement;
      return true;
    } else if (identical(node.elseStatement, _oldNode)) {
      node.elseStatement = _newNode as Statement;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitImplementsClause(ImplementsClause node) {
    if (_replaceInList(node.interfaces)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitImportDirective(ImportDirective node) {
    if (identical(node.prefix, _oldNode)) {
      node.prefix = _newNode as SimpleIdentifier;
      return true;
    }
    return visitNamespaceDirective(node);
  }

  @override
  bool visitIndexExpression(IndexExpression node) {
    if (identical(node.target, _oldNode)) {
      node.target = _newNode as Expression;
      return true;
    } else if (identical(node.index, _oldNode)) {
      node.index = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitInstanceCreationExpression(InstanceCreationExpression node) {
    if (identical(node.constructorName, _oldNode)) {
      node.constructorName = _newNode as ConstructorName;
      return true;
    } else if (identical(node.argumentList, _oldNode)) {
      node.argumentList = _newNode as ArgumentList;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitIntegerLiteral(IntegerLiteral node) => visitNode(node);

  @override
  bool visitInterpolationExpression(InterpolationExpression node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitInterpolationString(InterpolationString node) => visitNode(node);

  @override
  bool visitIsExpression(IsExpression node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    } else if (identical(node.type, _oldNode)) {
      node.type = _newNode as TypeName;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitLabel(Label node) {
    if (identical(node.label, _oldNode)) {
      node.label = _newNode as SimpleIdentifier;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitLabeledStatement(LabeledStatement node) {
    if (identical(node.statement, _oldNode)) {
      node.statement = _newNode as Statement;
      return true;
    } else if (_replaceInList(node.labels)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitLibraryDirective(LibraryDirective node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as LibraryIdentifier;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitLibraryIdentifier(LibraryIdentifier node) {
    if (_replaceInList(node.components)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitListLiteral(ListLiteral node) {
    if (_replaceInList(node.elements)) {
      return true;
    }
    return visitTypedLiteral(node);
  }

  @override
  bool visitMapLiteral(MapLiteral node) {
    if (_replaceInList(node.entries)) {
      return true;
    }
    return visitTypedLiteral(node);
  }

  @override
  bool visitMapLiteralEntry(MapLiteralEntry node) {
    if (identical(node.key, _oldNode)) {
      node.key = _newNode as Expression;
      return true;
    } else if (identical(node.value, _oldNode)) {
      node.value = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitMethodDeclaration(MethodDeclaration node) {
    if (identical(node.returnType, _oldNode)) {
      node.returnType = _newNode as TypeName;
      return true;
    } else if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.parameters, _oldNode)) {
      node.parameters = _newNode as FormalParameterList;
      return true;
    } else if (identical(node.body, _oldNode)) {
      node.body = _newNode as FunctionBody;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitMethodInvocation(MethodInvocation node) {
    if (identical(node.target, _oldNode)) {
      node.target = _newNode as Expression;
      return true;
    } else if (identical(node.methodName, _oldNode)) {
      node.methodName = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.argumentList, _oldNode)) {
      node.argumentList = _newNode as ArgumentList;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitNamedExpression(NamedExpression node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as Label;
      return true;
    } else if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  bool visitNamespaceDirective(NamespaceDirective node) {
    if (_replaceInList(node.combinators)) {
      return true;
    }
    return visitUriBasedDirective(node);
  }

  @override
  bool visitNativeClause(NativeClause node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as StringLiteral;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitNativeFunctionBody(NativeFunctionBody node) {
    if (identical(node.stringLiteral, _oldNode)) {
      node.stringLiteral = _newNode as StringLiteral;
      return true;
    }
    return visitNode(node);
  }

  bool visitNode(AstNode node) {
    throw new IllegalArgumentException(
        "The old node is not a child of it's parent");
  }

  bool visitNormalFormalParameter(NormalFormalParameter node) {
    if (identical(node.documentationComment, _oldNode)) {
      node.documentationComment = _newNode as Comment;
      return true;
    } else if (identical(node.identifier, _oldNode)) {
      node.identifier = _newNode as SimpleIdentifier;
      return true;
    } else if (_replaceInList(node.metadata)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitNullLiteral(NullLiteral node) => visitNode(node);

  @override
  bool visitParenthesizedExpression(ParenthesizedExpression node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitPartDirective(PartDirective node) => visitUriBasedDirective(node);

  @override
  bool visitPartOfDirective(PartOfDirective node) {
    if (identical(node.libraryName, _oldNode)) {
      node.libraryName = _newNode as LibraryIdentifier;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitPostfixExpression(PostfixExpression node) {
    if (identical(node.operand, _oldNode)) {
      node.operand = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitPrefixedIdentifier(PrefixedIdentifier node) {
    if (identical(node.prefix, _oldNode)) {
      node.prefix = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.identifier, _oldNode)) {
      node.identifier = _newNode as SimpleIdentifier;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitPrefixExpression(PrefixExpression node) {
    if (identical(node.operand, _oldNode)) {
      node.operand = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitPropertyAccess(PropertyAccess node) {
    if (identical(node.target, _oldNode)) {
      node.target = _newNode as Expression;
      return true;
    } else if (identical(node.propertyName, _oldNode)) {
      node.propertyName = _newNode as SimpleIdentifier;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitRedirectingConstructorInvocation(
      RedirectingConstructorInvocation node) {
    if (identical(node.constructorName, _oldNode)) {
      node.constructorName = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.argumentList, _oldNode)) {
      node.argumentList = _newNode as ArgumentList;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitRethrowExpression(RethrowExpression node) => visitNode(node);

  @override
  bool visitReturnStatement(ReturnStatement node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitScriptTag(ScriptTag scriptTag) => visitNode(scriptTag);

  @override
  bool visitShowCombinator(ShowCombinator node) {
    if (_replaceInList(node.shownNames)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitSimpleFormalParameter(SimpleFormalParameter node) {
    if (identical(node.type, _oldNode)) {
      node.type = _newNode as TypeName;
      return true;
    }
    return visitNormalFormalParameter(node);
  }

  @override
  bool visitSimpleIdentifier(SimpleIdentifier node) => visitNode(node);

  @override
  bool visitSimpleStringLiteral(SimpleStringLiteral node) => visitNode(node);

  @override
  bool visitStringInterpolation(StringInterpolation node) {
    if (_replaceInList(node.elements)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitSuperConstructorInvocation(SuperConstructorInvocation node) {
    if (identical(node.constructorName, _oldNode)) {
      node.constructorName = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.argumentList, _oldNode)) {
      node.argumentList = _newNode as ArgumentList;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitSuperExpression(SuperExpression node) => visitNode(node);

  @override
  bool visitSwitchCase(SwitchCase node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitSwitchMember(node);
  }

  @override
  bool visitSwitchDefault(SwitchDefault node) => visitSwitchMember(node);

  bool visitSwitchMember(SwitchMember node) {
    if (_replaceInList(node.labels)) {
      return true;
    } else if (_replaceInList(node.statements)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitSwitchStatement(SwitchStatement node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    } else if (_replaceInList(node.members)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitSymbolLiteral(SymbolLiteral node) => visitNode(node);

  @override
  bool visitThisExpression(ThisExpression node) => visitNode(node);

  @override
  bool visitThrowExpression(ThrowExpression node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
    if (identical(node.variables, _oldNode)) {
      node.variables = _newNode as VariableDeclarationList;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitTryStatement(TryStatement node) {
    if (identical(node.body, _oldNode)) {
      node.body = _newNode as Block;
      return true;
    } else if (identical(node.finallyBlock, _oldNode)) {
      node.finallyBlock = _newNode as Block;
      return true;
    } else if (_replaceInList(node.catchClauses)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitTypeArgumentList(TypeArgumentList node) {
    if (_replaceInList(node.arguments)) {
      return true;
    }
    return visitNode(node);
  }

  bool visitTypedLiteral(TypedLiteral node) {
    if (identical(node.typeArguments, _oldNode)) {
      node.typeArguments = _newNode as TypeArgumentList;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitTypeName(TypeName node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as Identifier;
      return true;
    } else if (identical(node.typeArguments, _oldNode)) {
      node.typeArguments = _newNode as TypeArgumentList;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitTypeParameter(TypeParameter node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.bound, _oldNode)) {
      node.bound = _newNode as TypeName;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitTypeParameterList(TypeParameterList node) {
    if (_replaceInList(node.typeParameters)) {
      return true;
    }
    return visitNode(node);
  }

  bool visitUriBasedDirective(UriBasedDirective node) {
    if (identical(node.uri, _oldNode)) {
      node.uri = _newNode as StringLiteral;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitVariableDeclaration(VariableDeclaration node) {
    if (identical(node.name, _oldNode)) {
      node.name = _newNode as SimpleIdentifier;
      return true;
    } else if (identical(node.initializer, _oldNode)) {
      node.initializer = _newNode as Expression;
      return true;
    }
    return visitAnnotatedNode(node);
  }

  @override
  bool visitVariableDeclarationList(VariableDeclarationList node) {
    if (identical(node.type, _oldNode)) {
      node.type = _newNode as TypeName;
      return true;
    } else if (_replaceInList(node.variables)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitVariableDeclarationStatement(VariableDeclarationStatement node) {
    if (identical(node.variables, _oldNode)) {
      node.variables = _newNode as VariableDeclarationList;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitWhileStatement(WhileStatement node) {
    if (identical(node.condition, _oldNode)) {
      node.condition = _newNode as Expression;
      return true;
    } else if (identical(node.body, _oldNode)) {
      node.body = _newNode as Statement;
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitWithClause(WithClause node) {
    if (_replaceInList(node.mixinTypes)) {
      return true;
    }
    return visitNode(node);
  }

  @override
  bool visitYieldStatement(YieldStatement node) {
    if (identical(node.expression, _oldNode)) {
      node.expression = _newNode as Expression;
      return true;
    }
    return visitNode(node);
  }

  bool _replaceInList(NodeList list) {
    int count = list.length;
    for (int i = 0; i < count; i++) {
      if (identical(_oldNode, list[i])) {
        list[i] = _newNode;
        return true;
      }
    }
    return false;
  }

  /**
   * Replace the [oldNode] with the [newNode] in the AST structure containing
   * the old node. Return `true` if the replacement was successful.
   *
   * Throws an [IllegalArgumentException] if either node is `null`, if the old
   * node does not have a parent node, or if the AST structure has been
   * corrupted.
   */
  static bool replace(AstNode oldNode, AstNode newNode) {
    if (oldNode == null || newNode == null) {
      throw new IllegalArgumentException(
          "The old and new nodes must be non-null");
    } else if (identical(oldNode, newNode)) {
      return true;
    }
    AstNode parent = oldNode.parent;
    if (parent == null) {
      throw new IllegalArgumentException(
          "The old node is not a child of another node");
    }
    NodeReplacer replacer = new NodeReplacer(oldNode, newNode);
    return parent.accept(replacer);
  }
}

/**
 * Traverse the AST from initial child node to successive parents, building a
 * collection of local variable and parameter names visible to the initial child
 * node. In case of name shadowing, the first name seen is the most specific one
 * so names are not redefined.
 *
 * Completion test code coverage is 95%. The two basic blocks that are not
 * executed cannot be executed. They are included for future reference.
 */
class ScopedNameFinder extends GeneralizingAstVisitor<Object> {
  Declaration _declarationNode;

  AstNode _immediateChild;

  Map<String, SimpleIdentifier> _locals =
      new HashMap<String, SimpleIdentifier>();

  final int _position;

  bool _referenceIsWithinLocalFunction = false;

  ScopedNameFinder(this._position);

  Declaration get declaration => _declarationNode;

  Map<String, SimpleIdentifier> get locals => _locals;

  @override
  Object visitBlock(Block node) {
    _checkStatements(node.statements);
    return super.visitBlock(node);
  }

  @override
  Object visitCatchClause(CatchClause node) {
    _addToScope(node.exceptionParameter);
    _addToScope(node.stackTraceParameter);
    return super.visitCatchClause(node);
  }

  @override
  Object visitConstructorDeclaration(ConstructorDeclaration node) {
    if (!identical(_immediateChild, node.parameters)) {
      _addParameters(node.parameters.parameters);
    }
    _declarationNode = node;
    return null;
  }

  @override
  Object visitFieldDeclaration(FieldDeclaration node) {
    _declarationNode = node;
    return null;
  }

  @override
  Object visitForEachStatement(ForEachStatement node) {
    DeclaredIdentifier loopVariable = node.loopVariable;
    if (loopVariable != null) {
      _addToScope(loopVariable.identifier);
    }
    return super.visitForEachStatement(node);
  }

  @override
  Object visitForStatement(ForStatement node) {
    if (!identical(_immediateChild, node.variables) && node.variables != null) {
      _addVariables(node.variables.variables);
    }
    return super.visitForStatement(node);
  }

  @override
  Object visitFunctionDeclaration(FunctionDeclaration node) {
    if (node.parent is! FunctionDeclarationStatement) {
      _declarationNode = node;
      return null;
    }
    return super.visitFunctionDeclaration(node);
  }

  @override
  Object visitFunctionDeclarationStatement(FunctionDeclarationStatement node) {
    _referenceIsWithinLocalFunction = true;
    return super.visitFunctionDeclarationStatement(node);
  }

  @override
  Object visitFunctionExpression(FunctionExpression node) {
    if (node.parameters != null &&
        !identical(_immediateChild, node.parameters)) {
      _addParameters(node.parameters.parameters);
    }
    return super.visitFunctionExpression(node);
  }

  @override
  Object visitMethodDeclaration(MethodDeclaration node) {
    _declarationNode = node;
    if (node.parameters == null) {
      return null;
    }
    if (!identical(_immediateChild, node.parameters)) {
      _addParameters(node.parameters.parameters);
    }
    return null;
  }

  @override
  Object visitNode(AstNode node) {
    _immediateChild = node;
    AstNode parent = node.parent;
    if (parent != null) {
      parent.accept(this);
    }
    return null;
  }

  @override
  Object visitSwitchMember(SwitchMember node) {
    _checkStatements(node.statements);
    return super.visitSwitchMember(node);
  }

  @override
  Object visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
    _declarationNode = node;
    return null;
  }

  @override
  Object visitTypeAlias(TypeAlias node) {
    _declarationNode = node;
    return null;
  }

  void _addParameters(NodeList<FormalParameter> vars) {
    for (FormalParameter var2 in vars) {
      _addToScope(var2.identifier);
    }
  }

  void _addToScope(SimpleIdentifier identifier) {
    if (identifier != null && _isInRange(identifier)) {
      String name = identifier.name;
      if (!_locals.containsKey(name)) {
        _locals[name] = identifier;
      }
    }
  }

  void _addVariables(NodeList<VariableDeclaration> variables) {
    for (VariableDeclaration variable in variables) {
      _addToScope(variable.name);
    }
  }

  /**
   * Check the given list of [statements] for any that come before the immediate
   * child and that define a name that would be visible to the immediate child.
   */
  void _checkStatements(List<Statement> statements) {
    for (Statement statement in statements) {
      if (identical(statement, _immediateChild)) {
        return;
      }
      if (statement is VariableDeclarationStatement) {
        _addVariables(statement.variables.variables);
      } else if (statement is FunctionDeclarationStatement &&
          !_referenceIsWithinLocalFunction) {
        _addToScope(statement.functionDeclaration.name);
      }
    }
  }

  bool _isInRange(AstNode node) {
    if (_position < 0) {
      // if source position is not set then all nodes are in range
      return true;
      // not reached
    }
    return node.end < _position;
  }
}

/**
 * A visitor used to write a source representation of a visited AST node (and
 * all of it's children) to a writer.
 */
class ToSourceVisitor implements AstVisitor<Object> {
  /**
   * The writer to which the source is to be written.
   */
  final PrintWriter _writer;

  /**
   * Initialize a newly created visitor to write source code representing the
   * visited nodes to the given [writer].
   */
  ToSourceVisitor(this._writer);

  @override
  Object visitAdjacentStrings(AdjacentStrings node) {
    _visitNodeListWithSeparator(node.strings, " ");
    return null;
  }

  @override
  Object visitAnnotation(Annotation node) {
    _writer.print('@');
    _visitNode(node.name);
    _visitNodeWithPrefix(".", node.constructorName);
    _visitNode(node.arguments);
    return null;
  }

  @override
  Object visitArgumentList(ArgumentList node) {
    _writer.print('(');
    _visitNodeListWithSeparator(node.arguments, ", ");
    _writer.print(')');
    return null;
  }

  @override
  Object visitAsExpression(AsExpression node) {
    _visitNode(node.expression);
    _writer.print(" as ");
    _visitNode(node.type);
    return null;
  }

  @override
  Object visitAssertStatement(AssertStatement node) {
    _writer.print("assert (");
    _visitNode(node.condition);
    if (node.message != null) {
      _writer.print(', ');
      _visitNode(node.message);
    }
    _writer.print(");");
    return null;
  }

  @override
  Object visitAssignmentExpression(AssignmentExpression node) {
    _visitNode(node.leftHandSide);
    _writer.print(' ');
    _writer.print(node.operator.lexeme);
    _writer.print(' ');
    _visitNode(node.rightHandSide);
    return null;
  }

  @override
  Object visitAwaitExpression(AwaitExpression node) {
    _writer.print("await ");
    _visitNode(node.expression);
    return null;
  }

  @override
  Object visitBinaryExpression(BinaryExpression node) {
    _visitNode(node.leftOperand);
    _writer.print(' ');
    _writer.print(node.operator.lexeme);
    _writer.print(' ');
    _visitNode(node.rightOperand);
    return null;
  }

  @override
  Object visitBlock(Block node) {
    _writer.print('{');
    _visitNodeListWithSeparator(node.statements, " ");
    _writer.print('}');
    return null;
  }

  @override
  Object visitBlockFunctionBody(BlockFunctionBody node) {
    Token keyword = node.keyword;
    if (keyword != null) {
      _writer.print(keyword.lexeme);
      if (node.star != null) {
        _writer.print('*');
      }
      _writer.print(' ');
    }
    _visitNode(node.block);
    return null;
  }

  @override
  Object visitBooleanLiteral(BooleanLiteral node) {
    _writer.print(node.literal.lexeme);
    return null;
  }

  @override
  Object visitBreakStatement(BreakStatement node) {
    _writer.print("break");
    _visitNodeWithPrefix(" ", node.label);
    _writer.print(";");
    return null;
  }

  @override
  Object visitCascadeExpression(CascadeExpression node) {
    _visitNode(node.target);
    _visitNodeList(node.cascadeSections);
    return null;
  }

  @override
  Object visitCatchClause(CatchClause node) {
    _visitNodeWithPrefix("on ", node.exceptionType);
    if (node.catchKeyword != null) {
      if (node.exceptionType != null) {
        _writer.print(' ');
      }
      _writer.print("catch (");
      _visitNode(node.exceptionParameter);
      _visitNodeWithPrefix(", ", node.stackTraceParameter);
      _writer.print(") ");
    } else {
      _writer.print(" ");
    }
    _visitNode(node.body);
    return null;
  }

  @override
  Object visitClassDeclaration(ClassDeclaration node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _visitTokenWithSuffix(node.abstractKeyword, " ");
    _writer.print("class ");
    _visitNode(node.name);
    _visitNode(node.typeParameters);
    _visitNodeWithPrefix(" ", node.extendsClause);
    _visitNodeWithPrefix(" ", node.withClause);
    _visitNodeWithPrefix(" ", node.implementsClause);
    _writer.print(" {");
    _visitNodeListWithSeparator(node.members, " ");
    _writer.print("}");
    return null;
  }

  @override
  Object visitClassTypeAlias(ClassTypeAlias node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    if (node.abstractKeyword != null) {
      _writer.print("abstract ");
    }
    _writer.print("class ");
    _visitNode(node.name);
    _visitNode(node.typeParameters);
    _writer.print(" = ");
    _visitNode(node.superclass);
    _visitNodeWithPrefix(" ", node.withClause);
    _visitNodeWithPrefix(" ", node.implementsClause);
    _writer.print(";");
    return null;
  }

  @override
  Object visitComment(Comment node) => null;

  @override
  Object visitCommentReference(CommentReference node) => null;

  @override
  Object visitCompilationUnit(CompilationUnit node) {
    ScriptTag scriptTag = node.scriptTag;
    NodeList<Directive> directives = node.directives;
    _visitNode(scriptTag);
    String prefix = scriptTag == null ? "" : " ";
    _visitNodeListWithSeparatorAndPrefix(prefix, directives, " ");
    prefix = scriptTag == null && directives.isEmpty ? "" : " ";
    _visitNodeListWithSeparatorAndPrefix(prefix, node.declarations, " ");
    return null;
  }

  @override
  Object visitConditionalExpression(ConditionalExpression node) {
    _visitNode(node.condition);
    _writer.print(" ? ");
    _visitNode(node.thenExpression);
    _writer.print(" : ");
    _visitNode(node.elseExpression);
    return null;
  }

  @override
  Object visitConfiguration(Configuration node) {
    _writer.print('if (');
    _visitNode(node.name);
    _visitNodeWithPrefix(" == ", node.value);
    _writer.print(') ');
    _visitNode(node.libraryUri);
    return null;
  }

  @override
  Object visitConstructorDeclaration(ConstructorDeclaration node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _visitTokenWithSuffix(node.externalKeyword, " ");
    _visitTokenWithSuffix(node.constKeyword, " ");
    _visitTokenWithSuffix(node.factoryKeyword, " ");
    _visitNode(node.returnType);
    _visitNodeWithPrefix(".", node.name);
    _visitNode(node.parameters);
    _visitNodeListWithSeparatorAndPrefix(" : ", node.initializers, ", ");
    _visitNodeWithPrefix(" = ", node.redirectedConstructor);
    _visitFunctionWithPrefix(" ", node.body);
    return null;
  }

  @override
  Object visitConstructorFieldInitializer(ConstructorFieldInitializer node) {
    _visitTokenWithSuffix(node.thisKeyword, ".");
    _visitNode(node.fieldName);
    _writer.print(" = ");
    _visitNode(node.expression);
    return null;
  }

  @override
  Object visitConstructorName(ConstructorName node) {
    _visitNode(node.type);
    _visitNodeWithPrefix(".", node.name);
    return null;
  }

  @override
  Object visitContinueStatement(ContinueStatement node) {
    _writer.print("continue");
    _visitNodeWithPrefix(" ", node.label);
    _writer.print(";");
    return null;
  }

  @override
  Object visitDeclaredIdentifier(DeclaredIdentifier node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _visitTokenWithSuffix(node.keyword, " ");
    _visitNodeWithSuffix(node.type, " ");
    _visitNode(node.identifier);
    return null;
  }

  @override
  Object visitDefaultFormalParameter(DefaultFormalParameter node) {
    _visitNode(node.parameter);
    if (node.separator != null) {
      _writer.print(" ");
      _writer.print(node.separator.lexeme);
      _visitNodeWithPrefix(" ", node.defaultValue);
    }
    return null;
  }

  @override
  Object visitDoStatement(DoStatement node) {
    _writer.print("do ");
    _visitNode(node.body);
    _writer.print(" while (");
    _visitNode(node.condition);
    _writer.print(");");
    return null;
  }

  @override
  Object visitDottedName(DottedName node) {
    _visitNodeListWithSeparator(node.components, ".");
    return null;
  }

  @override
  Object visitDoubleLiteral(DoubleLiteral node) {
    _writer.print(node.literal.lexeme);
    return null;
  }

  @override
  Object visitEmptyFunctionBody(EmptyFunctionBody node) {
    _writer.print(';');
    return null;
  }

  @override
  Object visitEmptyStatement(EmptyStatement node) {
    _writer.print(';');
    return null;
  }

  @override
  Object visitEnumConstantDeclaration(EnumConstantDeclaration node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _visitNode(node.name);
    return null;
  }

  @override
  Object visitEnumDeclaration(EnumDeclaration node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _writer.print("enum ");
    _visitNode(node.name);
    _writer.print(" {");
    _visitNodeListWithSeparator(node.constants, ", ");
    _writer.print("}");
    return null;
  }

  @override
  Object visitExportDirective(ExportDirective node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _writer.print("export ");
    _visitNode(node.uri);
    _visitNodeListWithSeparatorAndPrefix(" ", node.combinators, " ");
    _writer.print(';');
    return null;
  }

  @override
  Object visitExpressionFunctionBody(ExpressionFunctionBody node) {
    Token keyword = node.keyword;
    if (keyword != null) {
      _writer.print(keyword.lexeme);
      _writer.print(' ');
    }
    _writer.print("=> ");
    _visitNode(node.expression);
    if (node.semicolon != null) {
      _writer.print(';');
    }
    return null;
  }

  @override
  Object visitExpressionStatement(ExpressionStatement node) {
    _visitNode(node.expression);
    _writer.print(';');
    return null;
  }

  @override
  Object visitExtendsClause(ExtendsClause node) {
    _writer.print("extends ");
    _visitNode(node.superclass);
    return null;
  }

  @override
  Object visitFieldDeclaration(FieldDeclaration node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _visitTokenWithSuffix(node.staticKeyword, " ");
    _visitNode(node.fields);
    _writer.print(";");
    return null;
  }

  @override
  Object visitFieldFormalParameter(FieldFormalParameter node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, ' ', ' ');
    _visitTokenWithSuffix(node.keyword, " ");
    _visitNodeWithSuffix(node.type, " ");
    _writer.print("this.");
    _visitNode(node.identifier);
    _visitNode(node.typeParameters);
    _visitNode(node.parameters);
    return null;
  }

  @override
  Object visitForEachStatement(ForEachStatement node) {
    DeclaredIdentifier loopVariable = node.loopVariable;
    if (node.awaitKeyword != null) {
      _writer.print("await ");
    }
    _writer.print("for (");
    if (loopVariable == null) {
      _visitNode(node.identifier);
    } else {
      _visitNode(loopVariable);
    }
    _writer.print(" in ");
    _visitNode(node.iterable);
    _writer.print(") ");
    _visitNode(node.body);
    return null;
  }

  @override
  Object visitFormalParameterList(FormalParameterList node) {
    String groupEnd = null;
    _writer.print('(');
    NodeList<FormalParameter> parameters = node.parameters;
    int size = parameters.length;
    for (int i = 0; i < size; i++) {
      FormalParameter parameter = parameters[i];
      if (i > 0) {
        _writer.print(", ");
      }
      if (groupEnd == null && parameter is DefaultFormalParameter) {
        if (parameter.kind == ParameterKind.NAMED) {
          groupEnd = "}";
          _writer.print('{');
        } else {
          groupEnd = "]";
          _writer.print('[');
        }
      }
      parameter.accept(this);
    }
    if (groupEnd != null) {
      _writer.print(groupEnd);
    }
    _writer.print(')');
    return null;
  }

  @override
  Object visitForStatement(ForStatement node) {
    Expression initialization = node.initialization;
    _writer.print("for (");
    if (initialization != null) {
      _visitNode(initialization);
    } else {
      _visitNode(node.variables);
    }
    _writer.print(";");
    _visitNodeWithPrefix(" ", node.condition);
    _writer.print(";");
    _visitNodeListWithSeparatorAndPrefix(" ", node.updaters, ", ");
    _writer.print(") ");
    _visitNode(node.body);
    return null;
  }

  @override
  Object visitFunctionDeclaration(FunctionDeclaration node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _visitTokenWithSuffix(node.externalKeyword, " ");
    _visitNodeWithSuffix(node.returnType, " ");
    _visitTokenWithSuffix(node.propertyKeyword, " ");
    _visitNode(node.name);
    _visitNode(node.functionExpression);
    return null;
  }

  @override
  Object visitFunctionDeclarationStatement(FunctionDeclarationStatement node) {
    _visitNode(node.functionDeclaration);
    return null;
  }

  @override
  Object visitFunctionExpression(FunctionExpression node) {
    _visitNode(node.typeParameters);
    _visitNode(node.parameters);
    if (node.body is! EmptyFunctionBody) {
      _writer.print(' ');
    }
    _visitNode(node.body);
    return null;
  }

  @override
  Object visitFunctionExpressionInvocation(FunctionExpressionInvocation node) {
    _visitNode(node.function);
    _visitNode(node.typeArguments);
    _visitNode(node.argumentList);
    return null;
  }

  @override
  Object visitFunctionTypeAlias(FunctionTypeAlias node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _writer.print("typedef ");
    _visitNodeWithSuffix(node.returnType, " ");
    _visitNode(node.name);
    _visitNode(node.typeParameters);
    _visitNode(node.parameters);
    _writer.print(";");
    return null;
  }

  @override
  Object visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, ' ', ' ');
    _visitNodeWithSuffix(node.returnType, " ");
    _visitNode(node.identifier);
    _visitNode(node.typeParameters);
    _visitNode(node.parameters);
    return null;
  }

  @override
  Object visitHideCombinator(HideCombinator node) {
    _writer.print("hide ");
    _visitNodeListWithSeparator(node.hiddenNames, ", ");
    return null;
  }

  @override
  Object visitIfStatement(IfStatement node) {
    _writer.print("if (");
    _visitNode(node.condition);
    _writer.print(") ");
    _visitNode(node.thenStatement);
    _visitNodeWithPrefix(" else ", node.elseStatement);
    return null;
  }

  @override
  Object visitImplementsClause(ImplementsClause node) {
    _writer.print("implements ");
    _visitNodeListWithSeparator(node.interfaces, ", ");
    return null;
  }

  @override
  Object visitImportDirective(ImportDirective node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _writer.print("import ");
    _visitNode(node.uri);
    if (node.deferredKeyword != null) {
      _writer.print(" deferred");
    }
    _visitNodeWithPrefix(" as ", node.prefix);
    _visitNodeListWithSeparatorAndPrefix(" ", node.combinators, " ");
    _writer.print(';');
    return null;
  }

  @override
  Object visitIndexExpression(IndexExpression node) {
    if (node.isCascaded) {
      _writer.print("..");
    } else {
      _visitNode(node.target);
    }
    _writer.print('[');
    _visitNode(node.index);
    _writer.print(']');
    return null;
  }

  @override
  Object visitInstanceCreationExpression(InstanceCreationExpression node) {
    _visitTokenWithSuffix(node.keyword, " ");
    _visitNode(node.constructorName);
    _visitNode(node.argumentList);
    return null;
  }

  @override
  Object visitIntegerLiteral(IntegerLiteral node) {
    _writer.print(node.literal.lexeme);
    return null;
  }

  @override
  Object visitInterpolationExpression(InterpolationExpression node) {
    if (node.rightBracket != null) {
      _writer.print("\${");
      _visitNode(node.expression);
      _writer.print("}");
    } else {
      _writer.print("\$");
      _visitNode(node.expression);
    }
    return null;
  }

  @override
  Object visitInterpolationString(InterpolationString node) {
    _writer.print(node.contents.lexeme);
    return null;
  }

  @override
  Object visitIsExpression(IsExpression node) {
    _visitNode(node.expression);
    if (node.notOperator == null) {
      _writer.print(" is ");
    } else {
      _writer.print(" is! ");
    }
    _visitNode(node.type);
    return null;
  }

  @override
  Object visitLabel(Label node) {
    _visitNode(node.label);
    _writer.print(":");
    return null;
  }

  @override
  Object visitLabeledStatement(LabeledStatement node) {
    _visitNodeListWithSeparatorAndSuffix(node.labels, " ", " ");
    _visitNode(node.statement);
    return null;
  }

  @override
  Object visitLibraryDirective(LibraryDirective node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _writer.print("library ");
    _visitNode(node.name);
    _writer.print(';');
    return null;
  }

  @override
  Object visitLibraryIdentifier(LibraryIdentifier node) {
    _writer.print(node.name);
    return null;
  }

  @override
  Object visitListLiteral(ListLiteral node) {
    if (node.constKeyword != null) {
      _writer.print(node.constKeyword.lexeme);
      _writer.print(' ');
    }
    _visitNodeWithSuffix(node.typeArguments, " ");
    _writer.print("[");
    _visitNodeListWithSeparator(node.elements, ", ");
    _writer.print("]");
    return null;
  }

  @override
  Object visitMapLiteral(MapLiteral node) {
    if (node.constKeyword != null) {
      _writer.print(node.constKeyword.lexeme);
      _writer.print(' ');
    }
    _visitNodeWithSuffix(node.typeArguments, " ");
    _writer.print("{");
    _visitNodeListWithSeparator(node.entries, ", ");
    _writer.print("}");
    return null;
  }

  @override
  Object visitMapLiteralEntry(MapLiteralEntry node) {
    _visitNode(node.key);
    _writer.print(" : ");
    _visitNode(node.value);
    return null;
  }

  @override
  Object visitMethodDeclaration(MethodDeclaration node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _visitTokenWithSuffix(node.externalKeyword, " ");
    _visitTokenWithSuffix(node.modifierKeyword, " ");
    _visitNodeWithSuffix(node.returnType, " ");
    _visitTokenWithSuffix(node.propertyKeyword, " ");
    _visitTokenWithSuffix(node.operatorKeyword, " ");
    _visitNode(node.name);
    if (!node.isGetter) {
      _visitNode(node.typeParameters);
      _visitNode(node.parameters);
    }
    _visitFunctionWithPrefix(" ", node.body);
    return null;
  }

  @override
  Object visitMethodInvocation(MethodInvocation node) {
    if (node.isCascaded) {
      _writer.print("..");
    } else {
      if (node.target != null) {
        node.target.accept(this);
        _writer.print(node.operator.lexeme);
      }
    }
    _visitNode(node.methodName);
    _visitNode(node.typeArguments);
    _visitNode(node.argumentList);
    return null;
  }

  @override
  Object visitNamedExpression(NamedExpression node) {
    _visitNode(node.name);
    _visitNodeWithPrefix(" ", node.expression);
    return null;
  }

  @override
  Object visitNativeClause(NativeClause node) {
    _writer.print("native ");
    _visitNode(node.name);
    return null;
  }

  @override
  Object visitNativeFunctionBody(NativeFunctionBody node) {
    _writer.print("native ");
    _visitNode(node.stringLiteral);
    _writer.print(';');
    return null;
  }

  @override
  Object visitNullLiteral(NullLiteral node) {
    _writer.print("null");
    return null;
  }

  @override
  Object visitParenthesizedExpression(ParenthesizedExpression node) {
    _writer.print('(');
    _visitNode(node.expression);
    _writer.print(')');
    return null;
  }

  @override
  Object visitPartDirective(PartDirective node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _writer.print("part ");
    _visitNode(node.uri);
    _writer.print(';');
    return null;
  }

  @override
  Object visitPartOfDirective(PartOfDirective node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _writer.print("part of ");
    _visitNode(node.libraryName);
    _writer.print(';');
    return null;
  }

  @override
  Object visitPostfixExpression(PostfixExpression node) {
    _visitNode(node.operand);
    _writer.print(node.operator.lexeme);
    return null;
  }

  @override
  Object visitPrefixedIdentifier(PrefixedIdentifier node) {
    _visitNode(node.prefix);
    _writer.print('.');
    _visitNode(node.identifier);
    return null;
  }

  @override
  Object visitPrefixExpression(PrefixExpression node) {
    _writer.print(node.operator.lexeme);
    _visitNode(node.operand);
    return null;
  }

  @override
  Object visitPropertyAccess(PropertyAccess node) {
    if (node.isCascaded) {
      _writer.print("..");
    } else {
      _visitNode(node.target);
      _writer.print(node.operator.lexeme);
    }
    _visitNode(node.propertyName);
    return null;
  }

  @override
  Object visitRedirectingConstructorInvocation(
      RedirectingConstructorInvocation node) {
    _writer.print("this");
    _visitNodeWithPrefix(".", node.constructorName);
    _visitNode(node.argumentList);
    return null;
  }

  @override
  Object visitRethrowExpression(RethrowExpression node) {
    _writer.print("rethrow");
    return null;
  }

  @override
  Object visitReturnStatement(ReturnStatement node) {
    Expression expression = node.expression;
    if (expression == null) {
      _writer.print("return;");
    } else {
      _writer.print("return ");
      expression.accept(this);
      _writer.print(";");
    }
    return null;
  }

  @override
  Object visitScriptTag(ScriptTag node) {
    _writer.print(node.scriptTag.lexeme);
    return null;
  }

  @override
  Object visitShowCombinator(ShowCombinator node) {
    _writer.print("show ");
    _visitNodeListWithSeparator(node.shownNames, ", ");
    return null;
  }

  @override
  Object visitSimpleFormalParameter(SimpleFormalParameter node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, ' ', ' ');
    _visitTokenWithSuffix(node.keyword, " ");
    _visitNodeWithSuffix(node.type, " ");
    _visitNode(node.identifier);
    return null;
  }

  @override
  Object visitSimpleIdentifier(SimpleIdentifier node) {
    _writer.print(node.token.lexeme);
    return null;
  }

  @override
  Object visitSimpleStringLiteral(SimpleStringLiteral node) {
    _writer.print(node.literal.lexeme);
    return null;
  }

  @override
  Object visitStringInterpolation(StringInterpolation node) {
    _visitNodeList(node.elements);
    return null;
  }

  @override
  Object visitSuperConstructorInvocation(SuperConstructorInvocation node) {
    _writer.print("super");
    _visitNodeWithPrefix(".", node.constructorName);
    _visitNode(node.argumentList);
    return null;
  }

  @override
  Object visitSuperExpression(SuperExpression node) {
    _writer.print("super");
    return null;
  }

  @override
  Object visitSwitchCase(SwitchCase node) {
    _visitNodeListWithSeparatorAndSuffix(node.labels, " ", " ");
    _writer.print("case ");
    _visitNode(node.expression);
    _writer.print(": ");
    _visitNodeListWithSeparator(node.statements, " ");
    return null;
  }

  @override
  Object visitSwitchDefault(SwitchDefault node) {
    _visitNodeListWithSeparatorAndSuffix(node.labels, " ", " ");
    _writer.print("default: ");
    _visitNodeListWithSeparator(node.statements, " ");
    return null;
  }

  @override
  Object visitSwitchStatement(SwitchStatement node) {
    _writer.print("switch (");
    _visitNode(node.expression);
    _writer.print(") {");
    _visitNodeListWithSeparator(node.members, " ");
    _writer.print("}");
    return null;
  }

  @override
  Object visitSymbolLiteral(SymbolLiteral node) {
    _writer.print("#");
    List<Token> components = node.components;
    for (int i = 0; i < components.length; i++) {
      if (i > 0) {
        _writer.print(".");
      }
      _writer.print(components[i].lexeme);
    }
    return null;
  }

  @override
  Object visitThisExpression(ThisExpression node) {
    _writer.print("this");
    return null;
  }

  @override
  Object visitThrowExpression(ThrowExpression node) {
    _writer.print("throw ");
    _visitNode(node.expression);
    return null;
  }

  @override
  Object visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
    _visitNodeWithSuffix(node.variables, ";");
    return null;
  }

  @override
  Object visitTryStatement(TryStatement node) {
    _writer.print("try ");
    _visitNode(node.body);
    _visitNodeListWithSeparatorAndPrefix(" ", node.catchClauses, " ");
    _visitNodeWithPrefix(" finally ", node.finallyBlock);
    return null;
  }

  @override
  Object visitTypeArgumentList(TypeArgumentList node) {
    _writer.print('<');
    _visitNodeListWithSeparator(node.arguments, ", ");
    _writer.print('>');
    return null;
  }

  @override
  Object visitTypeName(TypeName node) {
    _visitNode(node.name);
    _visitNode(node.typeArguments);
    return null;
  }

  @override
  Object visitTypeParameter(TypeParameter node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _visitNode(node.name);
    _visitNodeWithPrefix(" extends ", node.bound);
    return null;
  }

  @override
  Object visitTypeParameterList(TypeParameterList node) {
    _writer.print('<');
    _visitNodeListWithSeparator(node.typeParameters, ", ");
    _writer.print('>');
    return null;
  }

  @override
  Object visitVariableDeclaration(VariableDeclaration node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _visitNode(node.name);
    _visitNodeWithPrefix(" = ", node.initializer);
    return null;
  }

  @override
  Object visitVariableDeclarationList(VariableDeclarationList node) {
    _visitNodeListWithSeparatorAndSuffix(node.metadata, " ", " ");
    _visitTokenWithSuffix(node.keyword, " ");
    _visitNodeWithSuffix(node.type, " ");
    _visitNodeListWithSeparator(node.variables, ", ");
    return null;
  }

  @override
  Object visitVariableDeclarationStatement(VariableDeclarationStatement node) {
    _visitNode(node.variables);
    _writer.print(";");
    return null;
  }

  @override
  Object visitWhileStatement(WhileStatement node) {
    _writer.print("while (");
    _visitNode(node.condition);
    _writer.print(") ");
    _visitNode(node.body);
    return null;
  }

  @override
  Object visitWithClause(WithClause node) {
    _writer.print("with ");
    _visitNodeListWithSeparator(node.mixinTypes, ", ");
    return null;
  }

  @override
  Object visitYieldStatement(YieldStatement node) {
    if (node.star != null) {
      _writer.print("yield* ");
    } else {
      _writer.print("yield ");
    }
    _visitNode(node.expression);
    _writer.print(";");
    return null;
  }

  /**
   * Visit the given function [body], printing the [prefix] before if the body
   * is not empty.
   */
  void _visitFunctionWithPrefix(String prefix, FunctionBody body) {
    if (body is! EmptyFunctionBody) {
      _writer.print(prefix);
    }
    _visitNode(body);
  }

  /**
   * Safely visit the given [node].
   */
  void _visitNode(AstNode node) {
    if (node != null) {
      node.accept(this);
    }
  }

  /**
   * Print a list of [nodes] without any separation.
   */
  void _visitNodeList(NodeList<AstNode> nodes) {
    _visitNodeListWithSeparator(nodes, "");
  }

  /**
   * Print a list of [nodes], separated by the given [separator].
   */
  void _visitNodeListWithSeparator(NodeList<AstNode> nodes, String separator) {
    if (nodes != null) {
      int size = nodes.length;
      for (int i = 0; i < size; i++) {
        if (i > 0) {
          _writer.print(separator);
        }
        nodes[i].accept(this);
      }
    }
  }

  /**
   * Print a list of [nodes], prefixed by the given [prefix] if the list is not
   * empty, and separated by the given [separator].
   */
  void _visitNodeListWithSeparatorAndPrefix(
      String prefix, NodeList<AstNode> nodes, String separator) {
    if (nodes != null) {
      int size = nodes.length;
      if (size > 0) {
        _writer.print(prefix);
        for (int i = 0; i < size; i++) {
          if (i > 0) {
            _writer.print(separator);
          }
          nodes[i].accept(this);
        }
      }
    }
  }

  /**
   * Print a list of [nodes], separated by the given [separator], followed by
   * the given [suffix] if the list is not empty.
   */
  void _visitNodeListWithSeparatorAndSuffix(
      NodeList<AstNode> nodes, String separator, String suffix) {
    if (nodes != null) {
      int size = nodes.length;
      if (size > 0) {
        for (int i = 0; i < size; i++) {
          if (i > 0) {
            _writer.print(separator);
          }
          nodes[i].accept(this);
        }
        _writer.print(suffix);
      }
    }
  }

  /**
   * Safely visit the given [node], printing the [prefix] before the node if it
   * is non-`null`.
   */
  void _visitNodeWithPrefix(String prefix, AstNode node) {
    if (node != null) {
      _writer.print(prefix);
      node.accept(this);
    }
  }

  /**
   * Safely visit the given [node], printing the [suffix] after the node if it
   * is non-`null`.
   */
  void _visitNodeWithSuffix(AstNode node, String suffix) {
    if (node != null) {
      node.accept(this);
      _writer.print(suffix);
    }
  }

  /**
   * Safely visit the given [token], printing the [suffix] after the token if it
   * is non-`null`.
   */
  void _visitTokenWithSuffix(Token token, String suffix) {
    if (token != null) {
      _writer.print(token.lexeme);
      _writer.print(suffix);
    }
  }
}