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

sdk/lib/_internal/compiler/implementation/closure.dart

Index: sdk/lib/_internal/compiler/implementation/closure.dart
diff --git a/sdk/lib/_internal/compiler/implementation/closure.dart b/sdk/lib/_internal/compiler/implementation/closure.dart
deleted file mode 100644
index fc789509c25667936c296ef5b04cf27337a9061e..0000000000000000000000000000000000000000
--- a/sdk/lib/_internal/compiler/implementation/closure.dart
+++ /dev/null
@@ -1,1031 +0,0 @@
-// Copyright (c) 2012, 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 closureToClassMapper;
-
-import "elements/elements.dart";
-import "dart2jslib.dart";
-import "dart_types.dart";
-import "js_backend/js_backend.dart" show JavaScriptBackend;
-import "scanner/scannerlib.dart" show Token;
-import "tree/tree.dart";
-import "util/util.dart";
-import "elements/modelx.dart"
-    show BaseFunctionElementX,
-         ClassElementX,
-         ElementX,
-         LocalFunctionElementX;
-import "elements/visitor.dart" show ElementVisitor;
-
-import 'universe/universe.dart' show
-    Universe;
-
-class ClosureNamer {
-  String getClosureVariableName(String name, int id) {
-    return "${name}_$id";
-  }
-
-  void forgetElement(Element element) {}
-}
-
-class ClosureTask extends CompilerTask {
-  Map<Node, ClosureClassMap> closureMappingCache;
-  ClosureNamer namer;
-  ClosureTask(Compiler compiler, this.namer)
-      : closureMappingCache = new Map<Node, ClosureClassMap>(),
-        super(compiler);
-
-  String get name => "Closure Simplifier";
-
-  ClosureClassMap computeClosureToClassMapping(Element element,
-                                               Node node,
-                                               TreeElements elements) {
-    return measure(() {
-      ClosureClassMap cached = closureMappingCache[node];
-      if (cached != null) return cached;
-
-      ClosureTranslator translator =
-          new ClosureTranslator(compiler, elements, closureMappingCache, namer);
-
-      // The translator will store the computed closure-mappings inside the
-      // cache. One for given node and one for each nested closure.
-      if (node is FunctionExpression) {
-        translator.translateFunction(element, node);
-      } else if (element.isSynthesized) {
-        return new ClosureClassMap(null, null, null, new ThisLocal(element));
-      } else {
-        assert(element.isField);
-        VariableElement field = element;
-        if (field.initializer != null) {
-          // The lazy initializer of a static.
-          translator.translateLazyInitializer(element, node, field.initializer);
-        } else {
-          assert(element.isInstanceMember);
-          closureMappingCache[node] =
-              new ClosureClassMap(null, null, null, new ThisLocal(element));
-        }
-      }
-      assert(closureMappingCache[node] != null);
-      return closureMappingCache[node];
-    });
-  }
-
-  ClosureClassMap getMappingForNestedFunction(FunctionExpression node) {
-    return measure(() {
-      ClosureClassMap nestedClosureData = closureMappingCache[node];
-      if (nestedClosureData == null) {
-        compiler.internalError(node, "No closure cache.");
-      }
-      return nestedClosureData;
-    });
-  }
-
-  void forgetElement(var closure) {
-    ClosureClassElement cls;
-    if (closure is ClosureFieldElement) {
-      cls = closure.closureClass;
-    } else if (closure is SynthesizedCallMethodElementX) {
-      cls = closure.closureClass;
-    } else {
-      throw new SpannableAssertionFailure(
-          closure, 'Not a closure: $closure (${closure.runtimeType}).');
-    }
-    namer.forgetElement(cls);
-    compiler.enqueuer.codegen.forgetElement(cls);
-  }
-}
-
-/// Common interface for [BoxFieldElement] and [ClosureFieldElement] as
-/// non-elements.
-abstract class CapturedVariable {}
-
-// TODO(ahe): These classes continuously cause problems.  We need to
-// find a more general solution.
-class ClosureFieldElement extends ElementX
-    implements VariableElement, CapturedVariable {
-  /// The source variable this element refers to.
-  final Local local;
-
-  ClosureFieldElement(String name,
-                      this.local,
-                      ClosureClassElement enclosing)
-      : super(name, ElementKind.FIELD, enclosing);
-
-  /// Use [closureClass] instead.
-  @deprecated
-  get enclosingElement => super.enclosingElement;
-
-  ClosureClassElement get closureClass => super.enclosingElement;
-
-  MemberElement get memberContext => closureClass.methodElement.memberContext;
-
-  bool get hasNode => false;
-
-  Node get node {
-    throw new SpannableAssertionFailure(local,
-        'Should not access node of ClosureFieldElement.');
-  }
-
-  bool get hasResolvedAst => hasTreeElements;
-
-  ResolvedAst get resolvedAst {
-    return new ResolvedAst(this, null, treeElements);
-  }
-
-  Expression get initializer {
-    throw new SpannableAssertionFailure(local,
-        'Should not access initializer of ClosureFieldElement.');
-  }
-
-  bool get isInstanceMember => true;
-  bool get isAssignable => false;
-
-  DartType computeType(Compiler compiler) => type;
-
-  DartType get type {
-    if (local is LocalElement) {
-      LocalElement element = local;
-      return element.type;
-    }
-    return const DynamicType();
-  }
-
-  String toString() => "ClosureFieldElement($name)";
-
-  accept(ElementVisitor visitor) => visitor.visitClosureFieldElement(this);
-
-  Element get analyzableElement => closureClass.methodElement.analyzableElement;
-}
-
-// TODO(ahe): These classes continuously cause problems.  We need to find
-// a more general solution.
-class ClosureClassElement extends ClassElementX {
-  DartType rawType;
-  DartType thisType;
-  FunctionType callType;
-  /// Node that corresponds to this closure, used for source position.
-  final FunctionExpression node;
-
-  /**
-   * The element for the declaration of the function expression.
-   */
-  final LocalFunctionElement methodElement;
-
-  final List<ClosureFieldElement> _closureFields = <ClosureFieldElement>[];
-
-  ClosureClassElement(this.node,
-                      String name,
-                      Compiler compiler,
-                      LocalFunctionElement closure)
-      : this.methodElement = closure,
-        super(name,
-              closure.compilationUnit,
-              // By assigning a fresh class-id we make sure that the hashcode
-              // is unique, but also emit closure classes after all other
-              // classes (since the emitter sorts classes by their id).
-              compiler.getNextFreeClassId(),
-              STATE_DONE) {
-    JavaScriptBackend backend = compiler.backend;
-    ClassElement superclass = methodElement.isInstanceMember
-        ? backend.boundClosureClass
-        : backend.closureClass;
-    superclass.ensureResolved(compiler);
-    supertype = superclass.thisType;
-    interfaces = const Link<DartType>();
-    thisType = rawType = new InterfaceType(this);
-    allSupertypesAndSelf =
-        superclass.allSupertypesAndSelf.extendClass(thisType);
-    callType = methodElement.type;
-  }
-
-  Iterable<ClosureFieldElement> get closureFields => _closureFields;
-
-  void addField(ClosureFieldElement field, DiagnosticListener listener) {
-    _closureFields.add(field);
-    addMember(field, listener);
-  }
-
-  bool get hasNode => true;
-
-  bool get isClosure => true;
-
-  Token get position => node.getBeginToken();
-
-  Node parseNode(DiagnosticListener listener) => node;
-
-  // A [ClosureClassElement] is nested inside a function or initializer in terms
-  // of [enclosingElement], but still has to be treated as a top-level
-  // element.
-  bool get isTopLevel => true;
-
-  get enclosingElement => methodElement;
-
-  accept(ElementVisitor visitor) => visitor.visitClosureClassElement(this);
-}
-
-/// A local variable that contains the box object holding the [BoxFieldElement]
-/// fields.
-class BoxLocal extends Local {
-  final String name;
-  final ExecutableElement executableContext;
-
-  BoxLocal(this.name, this.executableContext);
-}
-
-// TODO(ngeoffray, ahe): These classes continuously cause problems.  We need to
-// find a more general solution.
-class BoxFieldElement extends ElementX
-    implements TypedElement, CapturedVariable {
-  final BoxLocal box;
-
-  BoxFieldElement(String name, this.variableElement, BoxLocal box)
-      : this.box = box,
-        super(name, ElementKind.FIELD, box.executableContext);
-
-  DartType computeType(Compiler compiler) => type;
-
-  DartType get type => variableElement.type;
-
-  final VariableElement variableElement;
-
-  accept(ElementVisitor visitor) => visitor.visitBoxFieldElement(this);
-}
-
-/// A local variable used encode the direct (uncaptured) references to [this].
-class ThisLocal extends Local {
-  final ExecutableElement executableContext;
-
-  ThisLocal(this.executableContext);
-
-  String get name => 'this';
-
-  ClassElement get enclosingClass => executableContext.enclosingClass;
-}
-
-/// Call method of a closure class.
-class SynthesizedCallMethodElementX extends BaseFunctionElementX {
-  final LocalFunctionElement expression;
-
-  SynthesizedCallMethodElementX(String name,
-                                LocalFunctionElementX other,
-                                ClosureClassElement enclosing)
-      : expression = other,
-        super(name, other.kind, other.modifiers, enclosing, false) {
-    functionSignatureCache = other.functionSignature;
-  }
-
-  /// Use [closureClass] instead.
-  @deprecated
-  get enclosingElement => super.enclosingElement;
-
-  ClosureClassElement get closureClass => super.enclosingElement;
-
-  MemberElement get memberContext {
-    return closureClass.methodElement.memberContext;
-  }
-
-  bool get hasNode => expression.hasNode;
-
-  FunctionExpression get node => expression.node;
-
-  FunctionExpression parseNode(DiagnosticListener listener) => node;
-
-  ResolvedAst get resolvedAst {
-    return new ResolvedAst(this, node, treeElements);
-  }
-
-  Element get analyzableElement => closureClass.methodElement.analyzableElement;
-}
-
-// The box-element for a scope, and the captured variables that need to be
-// stored in the box.
-class ClosureScope {
-  BoxLocal boxElement;
-  Map<VariableElement, BoxFieldElement> _capturedVariableMapping;
-
-  // If the scope is attached to a [For] contains the variables that are
-  // declared in the initializer of the [For] and that need to be boxed.
-  // Otherwise contains the empty List.
-  List<VariableElement> boxedLoopVariables = const <VariableElement>[];
-
-  ClosureScope(this.boxElement, this._capturedVariableMapping);
-
-  bool hasBoxedLoopVariables() => !boxedLoopVariables.isEmpty;
-
-  bool isCapturedVariable(VariableElement variable) {
-    return _capturedVariableMapping.containsKey(variable);
-  }
-
-  void forEachCapturedVariable(f(LocalVariableElement variable,
-                                 BoxFieldElement boxField)) {
-    _capturedVariableMapping.forEach(f);
-  }
-}
-
-class ClosureClassMap {
-  // The closure's element before any translation. Will be null for methods.
-  final LocalFunctionElement closureElement;
-  // The closureClassElement will be null for methods that are not local
-  // closures.
-  final ClosureClassElement closureClassElement;
-  // The callElement will be null for methods that are not local closures.
-  final FunctionElement callElement;
-  // The [thisElement] makes handling 'this' easier by treating it like any
-  // other argument. It is only set for instance-members.
-  final ThisLocal thisLocal;
-
-  // Maps free locals, arguments and function elements to their captured
-  // copies.
-  final Map<Local, CapturedVariable> _freeVariableMapping =
-      new Map<Local, CapturedVariable>();
-
-  // Maps closure-fields to their captured elements. This is somehow the inverse
-  // mapping of [freeVariableMapping], but whereas [freeVariableMapping] does
-  // not deal with boxes, here we map instance-fields (which might represent
-  // boxes) to their boxElement.
-  final Map<ClosureFieldElement, Local> _closureFieldMapping =
-      new Map<ClosureFieldElement, Local>();
-
-  // Maps scopes ([Loop] and [FunctionExpression] nodes) to their
-  // [ClosureScope] which contains their box and the
-  // captured variables that are stored in the box.
-  // This map will be empty if the method/closure of this [ClosureData] does not
-  // contain any nested closure.
-  final Map<Node, ClosureScope> capturingScopes = new Map<Node, ClosureScope>();
-
-  final Set<Local> usedVariablesInTry = new Set<Local>();
-
-  ClosureClassMap(this.closureElement,
-                  this.closureClassElement,
-                  this.callElement,
-                  this.thisLocal);
-
-  void addFreeVariable(Local element) {
-    assert(_freeVariableMapping[element] == null);
-    _freeVariableMapping[element] = null;
-  }
-
-  Iterable<Local> get freeVariables => _freeVariableMapping.keys;
-
-  bool isFreeVariable(Local element) {
-    return _freeVariableMapping.containsKey(element);
-  }
-
-  CapturedVariable getFreeVariableElement(Local element) {
-    return _freeVariableMapping[element];
-  }
-
-  /// Sets the free [variable] to be captured by the [boxField].
-  void setFreeVariableBoxField(Local variable,
-                               BoxFieldElement boxField) {
-    _freeVariableMapping[variable] = boxField;
-  }
-
-  /// Sets the free [variable] to be captured by the [closureField].
-  void setFreeVariableClosureField(Local variable,
-                                   ClosureFieldElement closureField) {
-    _freeVariableMapping[variable] = closureField;
-  }
-
-
-  void forEachFreeVariable(f(Local variable,
-                             CapturedVariable field)) {
-    _freeVariableMapping.forEach(f);
-  }
-
-  Local getLocalVariableForClosureField(ClosureFieldElement field) {
-    return _closureFieldMapping[field];
-  }
-
-  void setLocalVariableForClosureField(ClosureFieldElement field,
-      Local variable) {
-    _closureFieldMapping[field] = variable;
-  }
-
-  bool get isClosure => closureElement != null;
-
-  bool capturingScopesBox(Local variable) {
-    return capturingScopes.values.any((scope) {
-      return scope.boxedLoopVariables.contains(variable);
-    });
-  }
-
-  bool isVariableBoxed(Local variable) {
-    CapturedVariable copy = _freeVariableMapping[variable];
-    if (copy is BoxFieldElement) {
-      return true;
-    }
-    return capturingScopesBox(variable);
-  }
-
-  void forEachCapturedVariable(void f(Local variable,
-                                      CapturedVariable field)) {
-    _freeVariableMapping.forEach((variable, copy) {
-      if (variable is BoxLocal) return;
-      f(variable, copy);
-    });
-    capturingScopes.values.forEach((ClosureScope scope) {
-      scope.forEachCapturedVariable(f);
-    });
-  }
-
-  void forEachBoxedVariable(void f(LocalVariableElement local,
-                                   BoxFieldElement field)) {
-    _freeVariableMapping.forEach((variable, copy) {
-      if (!isVariableBoxed(variable)) return;
-      f(variable, copy);
-    });
-    capturingScopes.values.forEach((ClosureScope scope) {
-      scope.forEachCapturedVariable(f);
-    });
-  }
-
-  void removeMyselfFrom(Universe universe) {
-    _freeVariableMapping.values.forEach((e) {
-      universe.closurizedMembers.remove(e);
-      universe.fieldSetters.remove(e);
-      universe.fieldGetters.remove(e);
-    });
-  }
-}
-
-class ClosureTranslator extends Visitor {
-  final Compiler compiler;
-  final TreeElements elements;
-  int closureFieldCounter = 0;
-  int boxedFieldCounter = 0;
-  bool inTryStatement = false;
-  final Map<Node, ClosureClassMap> closureMappingCache;
-
-  // Map of captured variables. Initially they will map to `null`. If
-  // a variable needs to be boxed then the scope declaring the variable
-  // will update this to mapping to the capturing [BoxFieldElement].
-  Map<Local, BoxFieldElement> _capturedVariableMapping =
-      new Map<Local, BoxFieldElement>();
-
-  // List of encountered closures.
-  List<Expression> closures = <Expression>[];
-
-  // The local variables that have been declared in the current scope.
-  List<LocalVariableElement> scopeVariables;
-
-  // Keep track of the mutated local variables so that we don't need to box
-  // non-mutated variables.
-  Set<LocalVariableElement> mutatedVariables = new Set<LocalVariableElement>();
-
-  MemberElement outermostElement;
-  ExecutableElement executableContext;
-
-  // The closureData of the currentFunctionElement.
-  ClosureClassMap closureData;
-
-  ClosureNamer namer;
-
-  bool insideClosure = false;
-
-  ClosureTranslator(this.compiler,
-                    this.elements,
-                    this.closureMappingCache,
-                    this.namer);
-
-  bool isCapturedVariable(Local element) {
-    return _capturedVariableMapping.containsKey(element);
-  }
-
-  void addCapturedVariable(Node node, Local variable) {
-    if (_capturedVariableMapping[variable] != null) {
-      compiler.internalError(node, 'In closure analyzer.');
-    }
-    _capturedVariableMapping[variable] = null;
-  }
-
-  void setCapturedVariableBoxField(Local variable,
-      BoxFieldElement boxField) {
-    assert(isCapturedVariable(variable));
-    _capturedVariableMapping[variable] = boxField;
-  }
-
-  BoxFieldElement getCapturedVariableBoxField(Local variable) {
-    return _capturedVariableMapping[variable];
-  }
-
-  void translateFunction(Element element, FunctionExpression node) {
-    // For constructors the [element] and the [:elements[node]:] may differ.
-    // The [:elements[node]:] always points to the generative-constructor
-    // element, whereas the [element] might be the constructor-body element.
-    visit(node); // [visitFunctionExpression] will call [visitInvokable].
-    // When variables need to be boxed their [_capturedVariableMapping] is
-    // updated, but we delay updating the similar freeVariableMapping in the
-    // closure datas that capture these variables.
-    // The closures don't have their fields (in the closure class) set, either.
-    updateClosures();
-  }
-
-  void translateLazyInitializer(VariableElement element,
-                                VariableDefinitions node,
-                                Expression initializer) {
-    visitInvokable(element, node, () { visit(initializer); });
-    updateClosures();
-  }
-
-  // This function runs through all of the existing closures and updates their
-  // free variables to the boxed value. It also adds the field-elements to the
-  // class representing the closure.
-  void updateClosures() {
-    for (Expression closure in closures) {
-      // The captured variables that need to be stored in a field of the closure
-      // class.
-      Set<Local> fieldCaptures = new Set<Local>();
-      Set<BoxLocal> boxes = new Set<BoxLocal>();
-      ClosureClassMap data = closureMappingCache[closure];
-      // We get a copy of the keys and iterate over it, to avoid modifications
-      // to the map while iterating over it.
-      Iterable<Local> freeVariables = data.freeVariables.toList();
-      freeVariables.forEach((Local fromElement) {
-        assert(data.isFreeVariable(fromElement));
-        assert(data.getFreeVariableElement(fromElement) == null);
-        assert(isCapturedVariable(fromElement));
-        BoxFieldElement boxFieldElement =
-            getCapturedVariableBoxField(fromElement);
-        if (boxFieldElement == null) {
-          assert(fromElement is! BoxLocal);
-          // The variable has not been boxed.
-          fieldCaptures.add(fromElement);
-        } else {
-          // A boxed element.
-          data.setFreeVariableBoxField(fromElement, boxFieldElement);
-          boxes.add(boxFieldElement.box);
-        }
-      });
-      ClosureClassElement closureClass = data.closureClassElement;
-      assert(closureClass != null ||
-             (fieldCaptures.isEmpty && boxes.isEmpty));
-
-      void addClosureField(Local local, String name) {
-        ClosureFieldElement closureField =
-            new ClosureFieldElement(name, local, closureClass);
-        closureClass.addField(closureField, compiler);
-        data.setLocalVariableForClosureField(closureField, local);
-        data.setFreeVariableClosureField(local, closureField);
-      }
-
-      // Add the box elements first so we get the same ordering.
-      // TODO(sra): What is the canonical order of multiple boxes?
-      for (BoxLocal capturedElement in boxes) {
-        addClosureField(capturedElement, capturedElement.name);
-      }
-
-      /// Comparator for locals. Position boxes before elements.
-      int compareLocals(a, b) {
-        if (a is Element && b is Element) {
-          return Elements.compareByPosition(a, b);
-        } else if (a is Element) {
-          return 1;
-        } else if (b is Element) {
-          return -1;
-        } else {
-          return a.name.compareTo(b.name);
-        }
-      }
-
-      for (Local capturedLocal in fieldCaptures.toList()..sort(compareLocals)) {
-        int id = closureFieldCounter++;
-        String name = namer.getClosureVariableName(capturedLocal.name, id);
-        addClosureField(capturedLocal, name);
-      }
-      closureClass.reverseBackendMembers();
-    }
-  }
-
-  void useLocal(Local variable) {
-    // If the element is not declared in the current function and the element
-    // is not the closure itself we need to mark the element as free variable.
-    // Note that the check on [insideClosure] is not just an
-    // optimization: factories have type parameters as function
-    // parameters, and type parameters are declared in the class, not
-    // the factory.
-    bool inCurrentContext(Local variable) {
-      return variable == executableContext ||
-             variable.executableContext == executableContext;
-    }
-
-    if (insideClosure && !inCurrentContext(variable)) {
-      closureData.addFreeVariable(variable);
-    } else if (inTryStatement) {
-      // Don't mark the this-element or a self-reference. This would complicate
-      // things in the builder.
-      // Note that nested (named) functions are immutable.
-      if (variable != closureData.thisLocal &&
-          variable != closureData.closureElement) {
-        // TODO(ngeoffray): only do this if the variable is mutated.
-        closureData.usedVariablesInTry.add(variable);
-      }
-    }
-  }
-
-  void useTypeVariableAsLocal(TypeVariableType typeVariable) {
-    useLocal(new TypeVariableLocal(typeVariable, outermostElement));
-  }
-
-  void declareLocal(LocalVariableElement element) {
-    scopeVariables.add(element);
-  }
-
-  void registerNeedsThis() {
-    if (closureData.thisLocal != null) {
-      useLocal(closureData.thisLocal);
-    }
-  }
-
-  visit(Node node) => node.accept(this);
-
-  visitNode(Node node) => node.visitChildren(this);
-
-  visitVariableDefinitions(VariableDefinitions node) {
-    if (node.type != null) {
-      visit(node.type);
-    }
-    for (Link<Node> link = node.definitions.nodes;
-         !link.isEmpty;
-         link = link.tail) {
-      Node definition = link.head;
-      LocalElement element = elements[definition];
-      assert(element != null);
-      if (!element.isInitializingFormal) {
-        declareLocal(element);
-      }
-      // We still need to visit the right-hand sides of the init-assignments.
-      // For SendSets don't visit the left again. Otherwise it would be marked
-      // as mutated.
-      if (definition is Send) {
-        Send assignment = definition;
-        Node arguments = assignment.argumentsNode;
-        if (arguments != null) {
-          visit(arguments);
-        }
-      } else {
-        visit(definition);
-      }
-    }
-  }
-
-  visitTypeAnnotation(TypeAnnotation node) {
-    MemberElement member = executableContext.memberContext;
-    DartType type = elements.getType(node);
-    // TODO(karlklose,johnniwinther): if the type is null, the annotation is
-    // from a parameter which has been analyzed before the method has been
-    // resolved and the result has been thrown away.
-    if (compiler.enableTypeAssertions && type != null &&
-        type.containsTypeVariables) {
-      if (insideClosure && member.isFactoryConstructor) {
-        // This is a closure in a factory constructor.  Since there is no
-        // [:this:], we have to mark the type arguments as free variables to
-        // capture them in the closure.
-        type.forEachTypeVariable((TypeVariableType variable) {
-          useTypeVariableAsLocal(variable);
-        });
-      }
-      if (member.isInstanceMember && !member.isField) {
-        // In checked mode, using a type variable in a type annotation may lead
-        // to a runtime type check that needs to access the type argument and
-        // therefore the closure needs a this-element, if it is not in a field
-        // initializer; field initatializers are evaluated in a context where
-        // the type arguments are available in locals.
-        registerNeedsThis();
-      }
-    }
-  }
-
-  visitIdentifier(Identifier node) {
-    if (node.isThis()) {
-      registerNeedsThis();
-    } else {
-      Element element = elements[node];
-      if (element != null && element.isTypeVariable) {
-        if (outermostElement.isConstructor) {
-          TypeVariableElement typeVariable = element;
-          useTypeVariableAsLocal(typeVariable.type);
-        } else {
-          registerNeedsThis();
-        }
-      }
-    }
-    node.visitChildren(this);
-  }
-
-  visitSend(Send node) {
-    Element element = elements[node];
-    if (Elements.isLocal(element)) {
-      LocalElement localElement = element;
-      useLocal(localElement);
-    } else if (element != null && element.isTypeVariable) {
-      TypeVariableElement variable = element;
-      analyzeType(variable.type);
-    } else if (node.receiver == null &&
-               Elements.isInstanceSend(node, elements)) {
-      registerNeedsThis();
-    } else if (node.isSuperCall) {
-      registerNeedsThis();
-    } else if (node.isTypeTest || node.isTypeCast) {
-      TypeAnnotation annotation = node.typeAnnotationFromIsCheckOrCast;
-      DartType type = elements.getType(annotation);
-      analyzeType(type);
-    } else if (node.isTypeTest) {
-      DartType type = elements.getType(node.typeAnnotationFromIsCheckOrCast);
-      analyzeType(type);
-    } else if (node.isTypeCast) {
-      DartType type = elements.getType(node.arguments.head);
-      analyzeType(type);
-    } else if (elements.isAssert(node) && !compiler.enableUserAssertions) {
-      return;
-    }
-    node.visitChildren(this);
-  }
-
-  visitSendSet(SendSet node) {
-    Element element = elements[node];
-    if (Elements.isLocal(element)) {
-      mutatedVariables.add(element);
-      if (compiler.enableTypeAssertions) {
-        TypedElement typedElement = element;
-        analyzeTypeVariables(typedElement.type);
-      }
-    }
-    super.visitSendSet(node);
-  }
-
-  visitNewExpression(NewExpression node) {
-    DartType type = elements.getType(node);
-    analyzeType(type);
-    node.visitChildren(this);
-  }
-
-  void analyzeTypeVariables(DartType type) {
-    type.forEachTypeVariable((TypeVariableType typeVariable) {
-      // Field initializers are inlined and access the type variable as
-      // normal parameters.
-      if (!outermostElement.isField &&
-          !outermostElement.isConstructor) {
-        registerNeedsThis();
-      } else {
-        useTypeVariableAsLocal(typeVariable);
-      }
-    });
-  }
-
-  void analyzeType(DartType type) {
-    // TODO(johnniwinther): Find out why this can be null.
-    if (type == null) return;
-    if (outermostElement.isClassMember &&
-        compiler.backend.classNeedsRti(outermostElement.enclosingClass)) {
-      if (outermostElement.isConstructor ||
-          outermostElement.isField) {
-        analyzeTypeVariables(type);
-      } else if (outermostElement.isInstanceMember) {
-        if (type.containsTypeVariables) {
-          registerNeedsThis();
-        }
-      }
-    }
-  }
-
-  // If variables that are declared in the [node] scope are captured and need
-  // to be boxed create a box-element and update the [capturingScopes] in the
-  // current [closureData].
-  // The boxed variables are updated in the [capturedVariableMapping].
-  void attachCapturedScopeVariables(Node node) {
-    BoxLocal box = null;
-    Map<LocalVariableElement, BoxFieldElement> scopeMapping =
-        new Map<LocalVariableElement, BoxFieldElement>();
-
-    void boxCapturedVariable(LocalVariableElement variable) {
-      if (isCapturedVariable(variable)) {
-        if (box == null) {
-          // TODO(floitsch): construct better box names.
-          String boxName =
-              namer.getClosureVariableName('box', closureFieldCounter++);
-          box = new BoxLocal(boxName, executableContext);
-        }
-        String elementName = variable.name;
-        String boxedName =
-            namer.getClosureVariableName(elementName, boxedFieldCounter++);
-        // TODO(kasperl): Should this be a FieldElement instead?
-        BoxFieldElement boxed = new BoxFieldElement(boxedName, variable, box);
-        // No need to rename the fields of a box, so we give them a native name
-        // right now.
-        boxed.setFixedBackendName(boxedName);
-        scopeMapping[variable] = boxed;
-        setCapturedVariableBoxField(variable, boxed);
-      }
-    }
-
-    for (LocalVariableElement variable in scopeVariables) {
-      // No need to box non-assignable elements.
-      if (!variable.isAssignable) continue;
-      if (!mutatedVariables.contains(variable)) continue;
-      boxCapturedVariable(variable);
-    }
-    if (!scopeMapping.isEmpty) {
-      ClosureScope scope = new ClosureScope(box, scopeMapping);
-      closureData.capturingScopes[node] = scope;
-    }
-  }
-
-  void inNewScope(Node node, Function action) {
-    List<LocalVariableElement> oldScopeVariables = scopeVariables;
-    scopeVariables = <LocalVariableElement>[];
-    action();
-    attachCapturedScopeVariables(node);
-    mutatedVariables.removeAll(scopeVariables);
-    scopeVariables = oldScopeVariables;
-  }
-
-  visitLoop(Loop node) {
-    inNewScope(node, () {
-      node.visitChildren(this);
-    });
-  }
-
-  visitFor(For node) {
-    visitLoop(node);
-    // See if we have declared loop variables that need to be boxed.
-    if (node.initializer == null) return;
-    VariableDefinitions definitions = node.initializer.asVariableDefinitions();
-    if (definitions == null) return;
-    ClosureScope scopeData = closureData.capturingScopes[node];
-    if (scopeData == null) return;
-    List<LocalVariableElement> result = <LocalVariableElement>[];
-    for (Link<Node> link = definitions.definitions.nodes;
-         !link.isEmpty;
-         link = link.tail) {
-      Node definition = link.head;
-      LocalVariableElement element = elements[definition];
-      if (isCapturedVariable(element)) {
-        result.add(element);
-      }
-    }
-    scopeData.boxedLoopVariables = result;
-  }
-
-  /** Returns a non-unique name for the given closure element. */
-  String computeClosureName(Element element) {
-    Link<String> parts = const Link<String>();
-    String ownName = element.name;
-    if (ownName == null || ownName == "") {
-      parts = parts.prepend("closure");
-    } else {
-      parts = parts.prepend(ownName);
-    }
-    for (Element enclosingElement = element.enclosingElement;
-         enclosingElement != null &&
-             (enclosingElement.kind == ElementKind.GENERATIVE_CONSTRUCTOR_BODY
-              || enclosingElement.kind == ElementKind.GENERATIVE_CONSTRUCTOR
-              || enclosingElement.kind == ElementKind.CLASS
-              || enclosingElement.kind == ElementKind.FUNCTION
-              || enclosingElement.kind == ElementKind.GETTER
-              || enclosingElement.kind == ElementKind.SETTER);
-         enclosingElement = enclosingElement.enclosingElement) {
-      // TODO(johnniwinther): Simplify computed names.
-      if (enclosingElement.isGenerativeConstructor ||
-          enclosingElement.isGenerativeConstructorBody ||
-          enclosingElement.isFactoryConstructor) {
-        parts = parts.prepend(
-            Elements.reconstructConstructorName(enclosingElement));
-      } else {
-        String surroundingName =
-            Elements.operatorNameToIdentifier(enclosingElement.name);
-        parts = parts.prepend(surroundingName);
-      }
-      // A generative constructors's parent is the class; the class name is
-      // already part of the generative constructor's name.
-      if (enclosingElement.kind == ElementKind.GENERATIVE_CONSTRUCTOR) break;
-    }
-    StringBuffer sb = new StringBuffer();
-    parts.printOn(sb, '_');
-    return sb.toString();
-  }
-
-  JavaScriptBackend get backend => compiler.backend;
-
-  ClosureClassMap globalizeClosure(FunctionExpression node,
-                                   LocalFunctionElement element) {
-    String closureName = computeClosureName(element);
-    ClosureClassElement globalizedElement = new ClosureClassElement(
-        node, closureName, compiler, element);
-    FunctionElement callElement =
-        new SynthesizedCallMethodElementX(Compiler.CALL_OPERATOR_NAME,
-                                          element,
-                                          globalizedElement);
-    backend.maybeMarkClosureAsNeededForReflection(globalizedElement, callElement, element);
-    MemberElement enclosing = element.memberContext;
-    enclosing.nestedClosures.add(callElement);
-    globalizedElement.addMember(callElement, compiler);
-    globalizedElement.computeAllClassMembers(compiler);
-    // The nested function's 'this' is the same as the one for the outer
-    // function. It could be [null] if we are inside a static method.
-    ThisLocal thisElement = closureData.thisLocal;
-
-    return new ClosureClassMap(element, globalizedElement,
-                               callElement, thisElement);
-  }
-
-  void visitInvokable(ExecutableElement element,
-                      Node node,
-                      void visitChildren()) {
-    bool oldInsideClosure = insideClosure;
-    Element oldFunctionElement = executableContext;
-    ClosureClassMap oldClosureData = closureData;
-
-    insideClosure = outermostElement != null;
-    LocalFunctionElement closure;
-    executableContext = element;
-    if (insideClosure) {
-      closure = element;
-      closures.add(node);
-      closureData = globalizeClosure(node, closure);
-    } else {
-      outermostElement = element;
-      ThisLocal thisElement = null;
-      if (element.isInstanceMember || element.isGenerativeConstructor) {
-        thisElement = new ThisLocal(element);
-      }
-      closureData = new ClosureClassMap(null, null, null, thisElement);
-    }
-    closureMappingCache[node] = closureData;
-
-    inNewScope(node, () {
-      DartType type = element.type;
-      // If the method needs RTI, or checked mode is set, we need to
-      // escape the potential type variables used in that closure.
-      if (element is FunctionElement &&
-          (compiler.backend.methodNeedsRti(element) ||
-           compiler.enableTypeAssertions)) {
-        analyzeTypeVariables(type);
-      }
-
-      visitChildren();
-    });
-
-
-    ClosureClassMap savedClosureData = closureData;
-    bool savedInsideClosure = insideClosure;
-
-    // Restore old values.
-    insideClosure = oldInsideClosure;
-    closureData = oldClosureData;
-    executableContext = oldFunctionElement;
-
-    // Mark all free variables as captured and use them in the outer function.
-    Iterable<Local> freeVariables = savedClosureData.freeVariables;
-    assert(freeVariables.isEmpty || savedInsideClosure);
-    for (Local freeVariable in freeVariables) {
-      addCapturedVariable(node, freeVariable);
-      useLocal(freeVariable);
-    }
-  }
-
-  visitFunctionExpression(FunctionExpression node) {
-    Element element = elements[node];
-
-    if (element.isParameter) {
-      // TODO(ahe): This is a hack. This method should *not* call
-      // visitChildren.
-      return node.name.accept(this);
-    }
-
-    visitInvokable(element, node, () {
-      // TODO(ahe): This is problematic. The backend should not repeat
-      // the work of the resolver. It is the resolver's job to create
-      // parameters, etc. Other phases should only visit statements.
-      if (node.parameters != null) node.parameters.accept(this);
-      if (node.initializers != null) node.initializers.accept(this);
-      if (node.body != null) node.body.accept(this);
-    });
-  }
-
-  visitTryStatement(TryStatement node) {
-    // TODO(ngeoffray): implement finer grain state.
-    bool oldInTryStatement = inTryStatement;
-    inTryStatement = true;
-    node.visitChildren(this);
-    inTryStatement = oldInTryStatement;
-  }
-}
-
-/// A type variable as a local variable.
-class TypeVariableLocal implements Local {
-  final TypeVariableType typeVariable;
-  final ExecutableElement executableContext;
-
-  TypeVariableLocal(this.typeVariable, this.executableContext);
-
-  String get name => typeVariable.name;
-
-  int get hashCode => typeVariable.hashCode;
-
-  bool operator ==(other) {
-    if (other is! TypeVariableLocal) return false;
-    return typeVariable == other.typeVariable;
-  }
-}