Revert "Move dart2js from sdk/lib/_internal/compiler to pkg/compiler"

pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart

Index: pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
diff --git a/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart b/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
deleted file mode 100644
index 7ceefa66b585b348a223d7065953f67102d0efb0..0000000000000000000000000000000000000000
--- a/pkg/compiler/lib/src/dart_backend/backend_ast_emitter.dart
+++ /dev/null
@@ -1,919 +0,0 @@
-// 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 backend_ast_emitter;
-
-import 'tree_ir_nodes.dart' as tree;
-import 'backend_ast_nodes.dart';
-import '../constants/expressions.dart';
-import '../constants/values.dart';
-import '../dart_types.dart';
-import '../elements/elements.dart';
-import '../elements/modelx.dart' as modelx;
-import '../universe/universe.dart';
-import '../tree/tree.dart' as tree show Modifiers;
-
-/// Translates the dart_tree IR to Dart backend AST.
-Expression emit(tree.FunctionDefinition definition) {
-  return new ASTEmitter().emit(definition);
-}
-
-/// Translates the dart_tree IR to Dart backend AST.
-/// An instance of this class should only be used once; a fresh emitter
-/// must be created for each function to be emitted.
-class ASTEmitter extends tree.Visitor<dynamic, Expression> {
-  /// Variables to be hoisted at the top of the current function.
-  List<VariableDeclaration> variables = <VariableDeclaration>[];
-
-  /// Maps variables to their name.
-  Map<tree.Variable, String> variableNames = <tree.Variable, String>{};
-
-  /// Maps local constants to their name.
-  Map<VariableElement, String> constantNames = <VariableElement, String>{};
-
-  /// Variables that have had their declaration created.
-  Set<tree.Variable> declaredVariables = new Set<tree.Variable>();
-
-  /// Variable names that have already been used. Used to avoid name clashes.
-  Set<String> usedVariableNames;
-
-  /// Statements emitted by the most recent call to [visitStatement].
-  List<Statement> statementBuffer = <Statement>[];
-
-  /// The function currently being emitted.
-  FunctionElement functionElement;
-
-  /// Bookkeeping object needed to synthesize a variable declaration.
-  modelx.VariableList variableList
-      = new modelx.VariableList(tree.Modifiers.EMPTY);
-
-  /// Input to [visitStatement]. Denotes the statement that will execute next
-  /// if the statements produced by [visitStatement] complete normally.
-  /// Set to null if control will fall over the end of the method.
-  tree.Statement fallthrough = null;
-
-  /// Labels that could not be eliminated using fallthrough.
-  Set<tree.Label> usedLabels = new Set<tree.Label>();
-
-  /// The first dart_tree statement that is not converted to a variable
-  /// initializer.
-  tree.Statement firstStatement;
-
-  /// Emitter for the enclosing function, or null if the current function is
-  /// not a local function.
-  ASTEmitter parent;
-
-  ASTEmitter() : usedVariableNames = new Set<String>();
-
-  ASTEmitter.inner(ASTEmitter parent)
-      : this.parent = parent,
-        usedVariableNames = parent.usedVariableNames;
-
-  FunctionExpression emit(tree.FunctionDefinition definition) {
-    functionElement = definition.element;
-
-    Parameters parameters = emitRootParameters(definition);
-
-    // Declare parameters.
-    for (tree.Variable param in definition.parameters) {
-      variableNames[param] = param.element.name;
-      usedVariableNames.add(param.element.name);
-      declaredVariables.add(param);
-    }
-
-    Statement body;
-    if (definition.isAbstract) {
-      body = new EmptyStatement();
-    } else {
-      firstStatement = definition.body;
-      visitStatement(definition.body);
-      removeTrailingReturn();
-
-      // Some of the variable declarations have already been added
-      // if their first assignment could be pulled into the initializer.
-      // Add the remaining variable declarations now.
-      for (tree.Variable variable in variableNames.keys) {
-        if (!declaredVariables.contains(variable)) {
-          addDeclaration(variable);
-        }
-      }
-
-      // Add constant declarations.
-      List<VariableDeclaration> constants = <VariableDeclaration>[];
-      for (ConstDeclaration constDecl in definition.localConstants) {
-        if (!constantNames.containsKey(constDecl.element))
-          continue; // Discard unused constants declarations.
-        String name = getConstantName(constDecl.element);
-        Expression value = emitConstant(constDecl.expression);
-        VariableDeclaration decl = new VariableDeclaration(name, value);
-        decl.element = constDecl.element;
-        constants.add(decl);
-      }
-
-      List<Statement> bodyParts = [];
-      if (constants.length > 0) {
-        bodyParts.add(new VariableDeclarations(constants, isConst: true));
-      }
-      if (variables.length > 0) {
-        bodyParts.add(new VariableDeclarations(variables));
-      }
-      bodyParts.addAll(statementBuffer);
-
-      body = new Block(bodyParts);
-    }
-    FunctionType functionType = functionElement.type;
-
-    return new FunctionExpression(
-        parameters,
-        body,
-        name: functionElement.name,
-        returnType: emitOptionalType(functionType.returnType),
-        isGetter: functionElement.isGetter,
-        isSetter: functionElement.isSetter)
-        ..element = functionElement;
-  }
-
-  void addDeclaration(tree.Variable variable, [Expression initializer]) {
-    assert(!declaredVariables.contains(variable));
-    String name = getVariableName(variable);
-    VariableDeclaration decl = new VariableDeclaration(name, initializer);
-    decl.element = variable.element;
-    declaredVariables.add(variable);
-    variables.add(decl);
-  }
-
-  /// Removes a trailing "return null" from [statementBuffer].
-  void removeTrailingReturn() {
-    if (statementBuffer.isEmpty) return;
-    if (statementBuffer.last is! Return) return;
-    Return ret = statementBuffer.last;
-    Expression expr = ret.expression;
-    if (expr is Literal && expr.value.isNull) {
-      statementBuffer.removeLast();
-    }
-  }
-
-  /// TODO(johnniwinther): Remove this when issue 21283 has been resolved.
-  int pseudoNameCounter = 0;
-
-  Parameter emitParameter(DartType type,
-                          {String name,
-                           Element element,
-                           ConstantExpression defaultValue}) {
-    if (name == null && element != null) {
-      name = element.name;
-    }
-    if (name == null) {
-      name = '_${pseudoNameCounter++}';
-    }
-    Parameter parameter;
-    if (type.isFunctionType) {
-      FunctionType functionType = type;
-      TypeAnnotation returnType = emitOptionalType(functionType.returnType);
-      Parameters innerParameters = emitParametersFromType(functionType);
-      parameter = new Parameter.function(name, returnType, innerParameters);
-    } else {
-      TypeAnnotation typeAnnotation = emitOptionalType(type);
-      parameter = new Parameter(name, type: typeAnnotation);
-    }
-    parameter.element = element;
-    if (defaultValue != null && !defaultValue.value.isNull) {
-      parameter.defaultValue = emitConstant(defaultValue);
-    }
-    return parameter;
-  }
-
-  Parameters emitParametersFromType(FunctionType functionType) {
-    if (functionType.namedParameters.isEmpty) {
-      return new Parameters(
-          emitParameters(functionType.parameterTypes),
-          emitParameters(functionType.optionalParameterTypes),
-          false);
-    } else {
-      return new Parameters(
-          emitParameters(functionType.parameterTypes),
-          emitParameters(functionType.namedParameterTypes,
-                         names: functionType.namedParameters),
-          true);
-    }
-  }
-
-  List<Parameter> emitParameters(
-      Iterable<DartType> parameterTypes,
-      {Iterable<String> names: const <String>[],
-       Iterable<ConstantExpression> defaultValues: const <ConstantExpression>[],
-       Iterable<Element> elements: const <Element>[]}) {
-    Iterator<String> name = names.iterator;
-    Iterator<ConstantExpression> defaultValue = defaultValues.iterator;
-    Iterator<Element> element = elements.iterator;
-    return parameterTypes.map((DartType type) {
-      name.moveNext();
-      defaultValue.moveNext();
-      element.moveNext();
-      return emitParameter(type,
-                           name: name.current,
-                           defaultValue: defaultValue.current,
-                           element: element.current);
-    }).toList();
-  }
-
-  /// Emits parameters that are not nested inside other parameters.
-  /// Root parameters can have default values, while inner parameters cannot.
-  Parameters emitRootParameters(tree.FunctionDefinition function) {
-    FunctionType functionType = function.element.type;
-    List<Parameter> required = emitParameters(
-        functionType.parameterTypes,
-        elements: function.parameters.map((p) => p.element));
-    bool optionalParametersAreNamed = !functionType.namedParameters.isEmpty;
-    List<Parameter> optional = emitParameters(
-        optionalParametersAreNamed
-            ? functionType.namedParameterTypes
-            : functionType.optionalParameterTypes,
-        defaultValues: function.defaultParameterValues,
-        elements: function.parameters.skip(required.length)
-            .map((p) => p.element));
-    return new Parameters(required, optional, optionalParametersAreNamed);
-  }
-
-  /// True if the two expressions are a reference to the same variable.
-  bool isSameVariable(Receiver e1, Receiver e2) {
-    return e1 is Identifier &&
-           e2 is Identifier &&
-           e1.element is VariableElement &&
-           e1.element == e2.element;
-  }
-
-  Expression makeAssignment(Expression target, Expression value) {
-    // Try to print as compound assignment or increment
-    if (value is BinaryOperator && isCompoundableOperator(value.operator)) {
-      Expression leftOperand = value.left;
-      Expression rightOperand = value.right;
-      bool valid = false;
-      if (isSameVariable(target, leftOperand)) {
-        valid = true;
-      } else if (target is FieldExpression &&
-                 leftOperand is FieldExpression &&
-                 isSameVariable(target.object, leftOperand.object) &&
-                 target.fieldName == leftOperand.fieldName) {
-        valid = true;
-      } else if (target is IndexExpression &&
-                 leftOperand is IndexExpression &&
-                 isSameVariable(target.object, leftOperand.object) &&
-                 isSameVariable(target.index, leftOperand.index)) {
-        valid = true;
-      }
-      if (valid) {
-        if (rightOperand is Literal && rightOperand.value.isOne &&
-            (value.operator == '+' || value.operator == '-')) {
-          return new Increment.prefix(target, value.operator + value.operator);
-        } else {
-          return new Assignment(target, value.operator + '=', rightOperand);
-        }
-      }
-    }
-    // Fall back to regular assignment
-    return new Assignment(target, '=', value);
-  }
-
-  void visitExpressionStatement(tree.ExpressionStatement stmt) {
-    Expression e = visitExpression(stmt.expression);
-    statementBuffer.add(new ExpressionStatement(e));
-    visitStatement(stmt.next);
-  }
-
-  void visitLabeledStatement(tree.LabeledStatement stmt) {
-    List<Statement> savedBuffer = statementBuffer;
-    tree.Statement savedFallthrough = fallthrough;
-    statementBuffer = <Statement>[];
-    fallthrough = stmt.next;
-    visitStatement(stmt.body);
-    if (usedLabels.remove(stmt.label)) {
-      savedBuffer.add(new LabeledStatement(stmt.label.name,
-                                           new Block(statementBuffer)));
-    } else {
-      savedBuffer.add(new Block(statementBuffer));
-    }
-    fallthrough = savedFallthrough;
-    statementBuffer = savedBuffer;
-    visitStatement(stmt.next);
-  }
-
-  /// Generates a name for the given variable and synthesizes an element for it,
-  /// if necessary.
-  String getVariableName(tree.Variable variable) {
-    // If the variable belongs to an enclosing function, ask the parent emitter
-    // for the variable name.
-    if (variable.host.element != functionElement) {
-      return parent.getVariableName(variable);
-    }
-
-    // Get the name if we already have one.
-    String name = variableNames[variable];
-    if (name != null) {
-      return name;
-    }
-
-    // Synthesize a variable name that isn't used elsewhere.
-    // The [usedVariableNames] set is shared between nested emitters,
-    // so this also prevents clash with variables in an enclosing/inner scope.
-    // The renaming phase after codegen will further prefix local variables
-    // so they cannot clash with top-level variables or fields.
-    String prefix = variable.element == null ? 'v' : variable.element.name;
-    int counter = 0;
-    name = variable.element == null ? '$prefix$counter' : variable.element.name;
-    while (!usedVariableNames.add(name)) {
-      ++counter;
-      name = '$prefix$counter';
-    }
-    variableNames[variable] = name;
-
-    // Synthesize an element for the variable
-    if (variable.element == null || name != variable.element.name) {
-      // TODO(johnniwinther): Replace by synthetic [Entity].
-      variable.element = new _SyntheticLocalVariableElement(
-          name,
-          functionElement,
-          variableList);
-    }
-    return name;
-  }
-
-  String getConstantName(VariableElement element) {
-    assert(element.kind == ElementKind.VARIABLE);
-    if (element.enclosingElement != functionElement) {
-      return parent.getConstantName(element);
-    }
-    String name = constantNames[element];
-    if (name != null) {
-      return name;
-    }
-    String prefix = element.name;
-    int counter = 0;
-    name = element.name;
-    while (!usedVariableNames.add(name)) {
-      ++counter;
-      name = '$prefix$counter';
-    }
-    constantNames[element] = name;
-    return name;
-  }
-
-  bool isNullLiteral(Expression exp) => exp is Literal && exp.value.isNull;
-
-  void visitAssign(tree.Assign stmt) {
-    // Try to emit a local function declaration. This is useful for functions
-    // that may occur in expression context, but could not be inlined anywhere.
-    if (stmt.variable.element is FunctionElement &&
-        stmt.definition is tree.FunctionExpression &&
-        !declaredVariables.contains(stmt.variable)) {
-      tree.FunctionExpression functionExp = stmt.definition;
-      FunctionExpression function = makeSubFunction(functionExp.definition);
-      FunctionDeclaration decl = new FunctionDeclaration(function);
-      statementBuffer.add(decl);
-      declaredVariables.add(stmt.variable);
-      visitStatement(stmt.next);
-      return;
-    }
-
-    bool isFirstOccurrence = (variableNames[stmt.variable] == null);
-    bool isDeclaredHere = stmt.variable.host.element == functionElement;
-    String name = getVariableName(stmt.variable);
-    Expression definition = visitExpression(stmt.definition);
-
-    // Try to pull into initializer.
-    if (firstStatement == stmt && isFirstOccurrence && isDeclaredHere) {
-      if (isNullLiteral(definition)) definition = null;
-      addDeclaration(stmt.variable, definition);
-      firstStatement = stmt.next;
-      visitStatement(stmt.next);
-      return;
-    }
-
-    // Emit a variable declaration if we are required to do so.
-    // This is to ensure that a fresh closure variable is created.
-    if (stmt.isDeclaration) {
-      assert(isFirstOccurrence);
-      assert(isDeclaredHere);
-      if (isNullLiteral(definition)) definition = null;
-      VariableDeclaration decl = new VariableDeclaration(name, definition)
-                                     ..element = stmt.variable.element;
-      declaredVariables.add(stmt.variable);
-      statementBuffer.add(new VariableDeclarations([decl]));
-      visitStatement(stmt.next);
-      return;
-    }
-
-    statementBuffer.add(new ExpressionStatement(makeAssignment(
-        visitVariable(stmt.variable),
-        definition)));
-    visitStatement(stmt.next);
-  }
-
-  void visitReturn(tree.Return stmt) {
-    Expression inner = visitExpression(stmt.value);
-    statementBuffer.add(new Return(inner));
-  }
-
-  void visitBreak(tree.Break stmt) {
-    tree.Statement fall = fallthrough;
-    if (stmt.target.binding.next == fall) {
-      // Fall through to break target
-    } else if (fall is tree.Break && fall.target == stmt.target) {
-      // Fall through to equivalent break
-    } else {
-      usedLabels.add(stmt.target);
-      statementBuffer.add(new Break(stmt.target.name));
-    }
-  }
-
-  void visitContinue(tree.Continue stmt) {
-    tree.Statement fall = fallthrough;
-    if (stmt.target.binding == fall) {
-      // Fall through to continue target
-    } else if (fall is tree.Continue && fall.target == stmt.target) {
-      // Fall through to equivalent continue
-    } else {
-      usedLabels.add(stmt.target);
-      statementBuffer.add(new Continue(stmt.target.name));
-    }
-  }
-
-  void visitIf(tree.If stmt) {
-    Expression condition = visitExpression(stmt.condition);
-    List<Statement> savedBuffer = statementBuffer;
-    List<Statement> thenBuffer = statementBuffer = <Statement>[];
-    visitStatement(stmt.thenStatement);
-    List<Statement> elseBuffer = statementBuffer = <Statement>[];
-    visitStatement(stmt.elseStatement);
-    savedBuffer.add(
-        new If(condition, new Block(thenBuffer), new Block(elseBuffer)));
-    statementBuffer = savedBuffer;
-  }
-
-  void visitWhileTrue(tree.WhileTrue stmt) {
-    List<Statement> savedBuffer = statementBuffer;
-    tree.Statement savedFallthrough = fallthrough;
-    statementBuffer = <Statement>[];
-    fallthrough = stmt;
-
-    visitStatement(stmt.body);
-    Statement body = new Block(statementBuffer);
-    Statement statement = new While(new Literal(new TrueConstantValue()),
-                                    body);
-    if (usedLabels.remove(stmt.label)) {
-      statement = new LabeledStatement(stmt.label.name, statement);
-    }
-    savedBuffer.add(statement);
-
-    statementBuffer = savedBuffer;
-    fallthrough = savedFallthrough;
-  }
-
-  void visitWhileCondition(tree.WhileCondition stmt) {
-    Expression condition = visitExpression(stmt.condition);
-
-    List<Statement> savedBuffer = statementBuffer;
-    tree.Statement savedFallthrough = fallthrough;
-    statementBuffer = <Statement>[];
-    fallthrough = stmt;
-
-    visitStatement(stmt.body);
-    Statement body = new Block(statementBuffer);
-    Statement statement;
-    statement = new While(condition, body);
-    if (usedLabels.remove(stmt.label)) {
-      statement = new LabeledStatement(stmt.label.name, statement);
-    }
-    savedBuffer.add(statement);
-
-    statementBuffer = savedBuffer;
-    fallthrough = savedFallthrough;
-
-    visitStatement(stmt.next);
-  }
-
-  Expression visitConstant(tree.Constant exp) {
-    return emitConstant(exp.expression);
-  }
-
-  Expression visitThis(tree.This exp) {
-    return new This();
-  }
-
-  Expression visitReifyTypeVar(tree.ReifyTypeVar exp) {
-    return new ReifyTypeVar(exp.typeVariable.name)
-               ..element = exp.typeVariable;
-  }
-
-  Expression visitLiteralList(tree.LiteralList exp) {
-    return new LiteralList(
-        exp.values.map(visitExpression).toList(growable: false),
-        typeArgument: emitOptionalType(exp.type.typeArguments.single));
-  }
-
-  Expression visitLiteralMap(tree.LiteralMap exp) {
-    List<LiteralMapEntry> entries = new List<LiteralMapEntry>.generate(
-        exp.entries.length,
-        (i) => new LiteralMapEntry(visitExpression(exp.entries[i].key),
-                                   visitExpression(exp.entries[i].value)));
-    List<TypeAnnotation> typeArguments = exp.type.treatAsRaw
-        ? null
-        : exp.type.typeArguments.map(createTypeAnnotation)
-             .toList(growable: false);
-    return new LiteralMap(entries, typeArguments: typeArguments);
-  }
-
-  Expression visitTypeOperator(tree.TypeOperator exp) {
-    return new TypeOperator(visitExpression(exp.receiver),
-                            exp.operator,
-                            createTypeAnnotation(exp.type));
-  }
-
-  List<Argument> emitArguments(tree.Invoke exp) {
-    List<tree.Expression> args = exp.arguments;
-    int positionalArgumentCount = exp.selector.positionalArgumentCount;
-    List<Argument> result = new List<Argument>.generate(positionalArgumentCount,
-        (i) => visitExpression(exp.arguments[i]));
-    for (int i = 0; i < exp.selector.namedArgumentCount; ++i) {
-      result.add(new NamedArgument(exp.selector.namedArguments[i],
-          visitExpression(exp.arguments[positionalArgumentCount + i])));
-    }
-    return result;
-  }
-
-  Expression visitInvokeStatic(tree.InvokeStatic exp) {
-    switch (exp.selector.kind) {
-      case SelectorKind.GETTER:
-        return new Identifier(exp.target.name)..element = exp.target;
-
-      case SelectorKind.SETTER:
-        return new Assignment(
-            new Identifier(exp.target.name)..element = exp.target,
-            '=',
-            visitExpression(exp.arguments[0]));
-
-      case SelectorKind.CALL:
-        return new CallStatic(null, exp.target.name, emitArguments(exp))
-                   ..element = exp.target;
-
-      default:
-        throw "Unexpected selector kind: ${exp.selector.kind}";
-    }
-  }
-
-  Expression emitMethodCall(tree.Invoke exp, Receiver receiver) {
-    List<Argument> args = emitArguments(exp);
-    switch (exp.selector.kind) {
-      case SelectorKind.CALL:
-        if (exp.selector.name == "call") {
-          return new CallFunction(receiver, args);
-        }
-        return new CallMethod(receiver, exp.selector.name, args);
-
-      case SelectorKind.OPERATOR:
-        if (args.length == 0) {
-          String name = exp.selector.name;
-          if (name == 'unary-') {
-            name = '-';
-          }
-          return new UnaryOperator(name, receiver);
-        }
-        return new BinaryOperator(receiver, exp.selector.name, args[0]);
-
-      case SelectorKind.GETTER:
-        return new FieldExpression(receiver, exp.selector.name);
-
-      case SelectorKind.SETTER:
-        return makeAssignment(
-            new FieldExpression(receiver, exp.selector.name),
-            args[0]);
-
-      case SelectorKind.INDEX:
-        Expression e = new IndexExpression(receiver, args[0]);
-        if (args.length == 2) {
-          e = makeAssignment(e, args[1]);
-        }
-        return e;
-
-      default:
-        throw "Unexpected selector in InvokeMethod: ${exp.selector.kind}";
-    }
-  }
-
-  Expression visitInvokeMethod(tree.InvokeMethod exp) {
-    Expression receiver = visitExpression(exp.receiver);
-    return emitMethodCall(exp, receiver);
-  }
-
-  Expression visitInvokeSuperMethod(tree.InvokeSuperMethod exp) {
-    return emitMethodCall(exp, new SuperReceiver());
-  }
-
-  Expression visitInvokeConstructor(tree.InvokeConstructor exp) {
-    List args = emitArguments(exp);
-    FunctionElement constructor = exp.target;
-    String name = constructor.name.isEmpty ? null : constructor.name;
-    return new CallNew(createTypeAnnotation(exp.type),
-                       args,
-                       constructorName: name,
-                       isConst: exp.constant != null)
-               ..constructor = constructor
-               ..dartType = exp.type;
-  }
-
-  Expression visitConcatenateStrings(tree.ConcatenateStrings exp) {
-    List args = exp.arguments.map(visitExpression).toList(growable:false);
-    return new StringConcat(args);
-  }
-
-  Expression visitConditional(tree.Conditional exp) {
-    return new Conditional(
-        visitExpression(exp.condition),
-        visitExpression(exp.thenExpression),
-        visitExpression(exp.elseExpression));
-  }
-
-  Expression visitLogicalOperator(tree.LogicalOperator exp) {
-    return new BinaryOperator(visitExpression(exp.left),
-                              exp.operator,
-                              visitExpression(exp.right));
-  }
-
-  Expression visitNot(tree.Not exp) {
-    return new UnaryOperator('!', visitExpression(exp.operand));
-  }
-
-  Expression visitVariable(tree.Variable exp) {
-    return new Identifier(getVariableName(exp))
-               ..element = exp.element;
-  }
-
-  FunctionExpression makeSubFunction(tree.FunctionDefinition function) {
-    return new ASTEmitter.inner(this).emit(function);
-  }
-
-  Expression visitFunctionExpression(tree.FunctionExpression exp) {
-    return makeSubFunction(exp.definition)..name = null;
-  }
-
-  void visitFunctionDeclaration(tree.FunctionDeclaration node) {
-    assert(variableNames[node.variable] == null);
-    String name = getVariableName(node.variable);
-    FunctionExpression inner = makeSubFunction(node.definition);
-    inner.name = name;
-    FunctionDeclaration decl = new FunctionDeclaration(inner);
-    declaredVariables.add(node.variable);
-    statementBuffer.add(decl);
-    visitStatement(node.next);
-  }
-
-  /// Like [createTypeAnnotation] except the dynamic type is converted to null.
-  TypeAnnotation emitOptionalType(DartType type) {
-    if (type.treatAsDynamic) {
-      return null;
-    } else {
-      return createTypeAnnotation(type);
-    }
-  }
-
-  Expression emitConstant(ConstantExpression exp) {
-    return new ConstantEmitter(this).visit(exp);
-  }
-}
-
-TypeAnnotation createTypeAnnotation(DartType type) {
-  if (type is GenericType) {
-    if (type.treatAsRaw) {
-      return new TypeAnnotation(type.element.name)..dartType = type;
-    }
-    return new TypeAnnotation(
-        type.element.name,
-        type.typeArguments.map(createTypeAnnotation).toList(growable:false))
-        ..dartType = type;
-  } else if (type is VoidType) {
-    return new TypeAnnotation('void')
-        ..dartType = type;
-  } else if (type is TypeVariableType) {
-    return new TypeAnnotation(type.name)
-        ..dartType = type;
-  } else if (type is DynamicType) {
-    return new TypeAnnotation("dynamic")
-        ..dartType = type;
-  } else if (type is MalformedType) {
-    return new TypeAnnotation(type.name)
-        ..dartType = type;
-  } else {
-    throw "Unsupported type annotation: $type";
-  }
-}
-
-class ConstantEmitter extends ConstantExpressionVisitor<Expression> {
-  ASTEmitter parent;
-  ConstantEmitter(this.parent);
-
-  Expression handlePrimitiveConstant(PrimitiveConstantValue value) {
-    // Num constants may be negative, while literals must be non-negative:
-    // Literals are non-negative in the specification, and a negated literal
-    // parses as a call to unary `-`. The AST unparser assumes literals are
-    // non-negative and relies on this to avoid incorrectly generating `--`,
-    // the predecrement operator.
-    // Translate such constants into their positive value wrapped by
-    // the unary minus operator.
-    if (value.isNum) {
-      NumConstantValue numConstant = value;
-      if (numConstant.primitiveValue.isNegative) {
-        return negatedLiteral(numConstant);
-      }
-    }
-    return new Literal(value);
-  }
-
-  @override
-  Expression visitPrimitive(PrimitiveConstantExpression exp) {
-    return handlePrimitiveConstant(exp.value);
-  }
-
-  /// Given a negative num constant, returns the corresponding positive
-  /// literal wrapped by a unary minus operator.
-  Expression negatedLiteral(NumConstantValue constant) {
-    assert(constant.primitiveValue.isNegative);
-    NumConstantValue positiveConstant;
-    if (constant.isInt) {
-      positiveConstant = new IntConstantValue(-constant.primitiveValue);
-    } else if (constant.isDouble) {
-      positiveConstant = new DoubleConstantValue(-constant.primitiveValue);
-    } else {
-      throw "Unexpected type of NumConstant: $constant";
-    }
-    return new UnaryOperator('-', new Literal(positiveConstant));
-  }
-
-  @override
-  Expression visitList(ListConstantExpression exp) {
-    return new LiteralList(
-        exp.values.map(visit).toList(growable: false),
-        isConst: true,
-        typeArgument: parent.emitOptionalType(exp.type.typeArguments.single));
-  }
-
-  @override
-  Expression visitMap(MapConstantExpression exp) {
-    List<LiteralMapEntry> entries = new List<LiteralMapEntry>.generate(
-        exp.values.length,
-        (i) => new LiteralMapEntry(visit(exp.keys[i]),
-                                   visit(exp.values[i])));
-    List<TypeAnnotation> typeArguments = exp.type.treatAsRaw
-        ? null
-        : exp.type.typeArguments.map(createTypeAnnotation).toList();
-    return new LiteralMap(entries, isConst: true, typeArguments: typeArguments);
-  }
-
-  @override
-  Expression visitConstructor(ConstructedConstantExpresssion exp) {
-    int positionalArgumentCount = exp.selector.positionalArgumentCount;
-    List<Argument> args = new List<Argument>.generate(
-        positionalArgumentCount,
-        (i) => visit(exp.arguments[i]));
-    for (int i = 0; i < exp.selector.namedArgumentCount; ++i) {
-      args.add(new NamedArgument(exp.selector.namedArguments[i],
-          visit(exp.arguments[positionalArgumentCount + i])));
-    }
-
-    FunctionElement constructor = exp.target;
-    String name = constructor.name.isEmpty ? null : constructor.name;
-    return new CallNew(createTypeAnnotation(exp.type),
-                       args,
-                       constructorName: name,
-                       isConst: true)
-               ..constructor = constructor
-               ..dartType = exp.type;
-  }
-
-  @override
-  Expression visitConcatenate(ConcatenateConstantExpression exp) {
-    return new StringConcat(exp.arguments.map(visit).toList(growable: false));
-  }
-
-  @override
-  Expression visitSymbol(SymbolConstantExpression exp) {
-    return new LiteralSymbol(exp.name);
-  }
-
-  @override
-  Expression visitType(TypeConstantExpression exp) {
-    DartType type = exp.type;
-    return new LiteralType(type.name)
-               ..type = type;
-  }
-
-  @override
-  Expression visitVariable(VariableConstantExpression exp) {
-    Element element = exp.element;
-    if (element.kind != ElementKind.VARIABLE) {
-      return new Identifier(element.name)..element = element;
-    }
-    String name = parent.getConstantName(element);
-    return new Identifier(name)
-               ..element = element;
-  }
-
-  @override
-  Expression visitFunction(FunctionConstantExpression exp) {
-    return new Identifier(exp.element.name)
-               ..element = exp.element;
-  }
-
-  @override
-  Expression visitBinary(BinaryConstantExpression exp) {
-    return handlePrimitiveConstant(exp.value);
-  }
-
-  @override
-  Expression visitConditional(ConditionalConstantExpression exp) {
-    if (exp.condition.value.isTrue) {
-      return exp.trueExp.accept(this);
-    } else {
-      return exp.falseExp.accept(this);
-    }
-  }
-
-  @override
-  Expression visitUnary(UnaryConstantExpression exp) {
-    return handlePrimitiveConstant(exp.value);
-  }
-}
-
-/// Moves function parameters into a separate variable if one of its uses is
-/// shadowed by an inner function parameter.
-/// This artifact is necessary because function parameters cannot be renamed.
-class UnshadowParameters extends tree.RecursiveVisitor {
-
-  /// Maps parameter names to their bindings.
-  Map<String, tree.Variable> environment = <String, tree.Variable>{};
-
-  /// Parameters that are currently shadowed by another parameter.
-  Set<tree.Variable> shadowedParameters = new Set<tree.Variable>();
-
-  /// Parameters that are used in a context where it is shadowed.
-  Set<tree.Variable> hasShadowedUse = new Set<tree.Variable>();
-
-  void unshadow(tree.FunctionDefinition definition) {
-    if (definition.isAbstract) return;
-
-    visitFunctionDefinition(definition);
-  }
-
-  visitFunctionDefinition(tree.FunctionDefinition definition) {
-    var oldShadow = shadowedParameters;
-    var oldEnvironment = environment;
-    environment = new Map<String, tree.Variable>.from(environment);
-    shadowedParameters = new Set<tree.Variable>.from(shadowedParameters);
-    for (tree.Variable param in definition.parameters) {
-      tree.Variable oldVariable = environment[param.element.name];
-      if (oldVariable != null) {
-        shadowedParameters.add(oldVariable);
-      }
-      environment[param.element.name] = param;
-    }
-    visitStatement(definition.body);
-    environment = oldEnvironment;
-    shadowedParameters = oldShadow;
-
-    for (int i=0; i<definition.parameters.length; i++) {
-      tree.Variable param = definition.parameters[i];
-      if (hasShadowedUse.remove(param)) {
-        tree.Variable newParam = new tree.Variable(definition, param.element);
-        definition.parameters[i] = newParam;
-        definition.body = new tree.Assign(param, newParam, definition.body);
-        newParam.writeCount = 1; // Being a parameter counts as a write.
-      }
-    }
-  }
-
-  visitVariable(tree.Variable variable) {
-    if (shadowedParameters.contains(variable)) {
-      hasShadowedUse.add(variable);
-    }
-  }
-
-}
-
-// TODO(johnniwinther): Remove this when the dart `backend_ast` does not need
-// [Element] for entities.
-class _SyntheticLocalVariableElement extends modelx.VariableElementX
-    implements LocalVariableElement {
-
-  _SyntheticLocalVariableElement(String name,
-                                 ExecutableElement enclosingElement,
-                                 modelx.VariableList variables)
-      : super(name, ElementKind.VARIABLE, enclosingElement, variables, null);
-
-  ExecutableElement get executableContext => enclosingElement;
-
-  ExecutableElement get memberContext => executableContext.memberContext;
-
-  bool get isLocal => true;
-
-  LibraryElement get implementationLibrary => enclosingElement.library;
-}