Support serialization of the compiler backbone.

pkg/compiler/lib/src/serialization/modelz.dart

+// Copyright (c) 2015, 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.
+
+/// Implementation of the element model used for deserialiation.
+///
+/// These classes are created by [ElementDeserializer] triggered by the
+/// [Deserializer].
+
+library dart2js.serialization.modelz;
+
+import 'serialization.dart';
+import 'keys.dart';
+import '../constants/expressions.dart';
+import '../dart2jslib.dart'
+    show Backend,
+         Compiler,
+         DiagnosticListener,
+         Script,
+         SourceSpan;
+import '../dart_types.dart';
+import '../elements/elements.dart';
+import '../elements/modelx.dart' show FunctionSignatureX;
+import '../elements/common.dart';
+import '../elements/visitor.dart';
+import '../ordered_typeset.dart';
+import '../resolution/resolution.dart';
+import '../resolution/class_members.dart' as class_members;
+import '../resolution/enum_creator.dart' show AstBuilder;
+import '../scanner/scannerlib.dart' show Token, SEMICOLON_INFO;
+import '../serialization/constant_serialization.dart';
+import '../io/source_file.dart';
+import '../tree/tree.dart';
+import '../util/util.dart' show Link, LinkBuilder;
+
+/// Compute a [Link] from an [Iterable].
+Link toLink(Iterable iterable) {
+  LinkBuilder builder = new LinkBuilder();
+  for (var element in iterable) {
+    builder.addLast(element);
+  }
+  return builder.toLink();
+}
+
+abstract class ElementZ extends Element with ElementCommon {
+  @override
+  bool get isFactoryConstructor => false;
+
+  String toString() {
+    if (enclosingElement == null || isTopLevel) return 'Z$kind($name)';
+    return 'Z$kind(${enclosingElement.name}#$name)';
+  }
+
+  _unsupported(text) => throw new UnsupportedError('${this}.$text');
+
+  @override
+  AnalyzableElement get analyzableElement {
+    Element element = this;
+    if (element is AnalyzableElement) {
+      return element;
+    } else if (enclosingElement != null) {
+      return enclosingElement.analyzableElement;
+    }
+    return null;
+  }
+
+  @override
+  FunctionElement asFunctionElement() => null;
+
+  @override
+  Scope buildScope() => _unsupported('analyzableElement');
+
+  @override
+  CompilationUnitElement get compilationUnit {
+    return _unsupported('compilationUnit');
+  }
+
+  @override
+  ClassElement get contextClass => _unsupported('contextClass');
+
+  @override
+  void diagnose(Element context, DiagnosticListener listener) {
+    _unsupported('diagnose');
+  }
+
+  @override
+  ClassElement get enclosingClass => null;
+
+  @override
+  Element get enclosingClassOrCompilationUnit {
+    return _unsupported('enclosingClassOrCompilationUnit');
+  }
+
+  @override
+  String get fixedBackendName => _unsupported('fixedBackendName');
+
+  @override
+  bool get hasFixedBackendName => _unsupported('hasFixedBackendName');
+
+  @override
+  LibraryElement get implementationLibrary => library;
+
+  @override
+  bool get isAbstract => false;
+
+  @override
+  bool get isAssignable => _unsupported('isAssignable');
+
+  @override
+  bool get isClassMember => false;
+
+  @override
+  bool get isClosure => _unsupported('isClosure');
+
+  @override
+  bool get isConst => _unsupported('isConst');
+
+  @override
+  bool get isDeferredLoaderGetter => false;
+
+  @override
+  bool get isFinal => _unsupported('isFinal');
+
+  @override
+  bool get isInstanceMember => false;
+
+  @override
+  bool get isLocal => false;
+
+  @override
+  bool get isMixinApplication => false;
+
+  @override
+  bool get isNative => false;
+
+  @override
+  bool get isOperator => false;
+
+  @override
+  bool get isStatic => false;
+
+  // TODO(johnniwinther): Find a more precise semantics for this.
+  @override
+  bool get isSynthesized => true;
+
+  @override
+  bool get isTopLevel => false;
+
+  // TODO(johnniwinther): Support metadata.
+  @override
+  Link<MetadataAnnotation> get metadata => const Link<MetadataAnnotation>();
+
+  @override
+  Element get outermostEnclosingMemberOrTopLevel {
+    return _unsupported('outermostEnclosingMemberOrTopLevel');
+  }
+
+  @override
+  Token get position => _unsupported('position');
+}
+
+abstract class DeserializedElementZ extends ElementZ {
+  ObjectDecoder _decoder;
+
+  DeserializedElementZ(this._decoder);
+
+  @override
+  String get name => _decoder.getString(Key.NAME);
+
+  @override
+  SourceSpan get sourcePosition {
+    // TODO(johnniwinther): Should this be cached?
+    int offset = _decoder.getInt(Key.OFFSET, isOptional: true);
+    if (offset == null) return null;
+    Uri uri = _decoder.getUri(Key.URI, isOptional: true);
+    if (uri == null) {
+      uri = compilationUnit.script.readableUri;
+    }
+    int length = _decoder.getInt(Key.LENGTH, isOptional: true);
+    if (length == null) {
+      length = name.length;
+    }
+    return new SourceSpan(uri, offset, offset + length);
+  }
+}
+
+/// Deserializer for a collection of member elements serialized as a map from
+/// names to element declarations.
+///
+/// The serialized data contains the declared getters and setters but lookup
+/// into the map returns an [AbstractFieldElement] for pairs of corresponding
+/// getters and setters.
+///
+/// The underlying map encoding allows for lazy computation of the members upon
+/// query.
+class MappedContainer {
+  Map<String, Element> _lookupMap = {};

[floitsch, 2015/07/03 17:06:25]

This is just a cache. right?
Either add a comment or rename.

[Johnni Winther, 2015/07/06 08:33:22]

Done.

+
+  Element lookup(String name, MapDecoder members) {
+    if (_lookupMap.containsKey(name)) {
+      Element element = _lookupMap[name];
+      if (element != null) {
+        return element;
+      }
+    }
+    if (members == null) {
+      return null;
+    }
+    bool hasId = members.containsKey(name);
+    String setterName = '$name,=';
+    bool hasSetterId = members.containsKey(setterName);
+    Element element;
+    Element setterElement;
+    if (!hasId && !hasSetterId) {
+      _lookupMap[name] = null;
+      return null;
+    }
+    bool isAccessor = false;
+    if (hasId) {
+      element = members.getElement(name);
+      isAccessor = element.isGetter;
+    }
+    if (hasSetterId) {
+      setterElement = members.getElement(setterName);
+      isAccessor = true;
+    }
+    if (isAccessor) {
+      element = new AbstractFieldElementZ(name, element, setterElement);
+    }
+    _lookupMap[name] = element;
+    return element;
+  }
+}
+
+/// Deserializer for a collection of member elements serialized as a list of
+/// element declarations.
+///
+/// The serialized data contains the declared getters and setters but lookup
+/// into the map returns an [AbstractFieldElement] for pairs of corresponding
+/// getters and setters.
+///
+/// The underlying list encoding requires the complete lookup map to be computed
+/// before query.
+class ListedContainer {
+  final Map<String, Element> _lookupMap = <String, Element>{};
+
+  ListedContainer(List<Element> elements) {
+    Set<String> accessorNames = new Set<String>();
+    Map<String, Element> getters = <String, Element>{};
+    Map<String, Element> setters = <String, Element>{};
+    for (Element element in elements) {
+      String name = element.name;
+      if (element.isGetter) {
+        accessorNames.add(name);
+        getters[name] = element;
+        _lookupMap[name] = element;

[floitsch, 2015/07/03 17:06:25]

The _lookupMap[name] will be overwritten below in line 266. Why adding it here?

same for setter.

[Johnni Winther, 2015/07/06 08:33:22]

Added a comment; [element] is inserted here to ensure insert order of [name].

+      } else if (element.isSetter) {
+        accessorNames.add(name);
+        setters[name] = element;
+        _lookupMap[name] = element;
+      } else {
+        _lookupMap[name] = element;
+      }
+    }
+    for (String name in accessorNames) {
+      _lookupMap[name] =
+          new AbstractFieldElementZ(name, getters[name], setters[name]);
+    }
+  }
+
+  Element lookup(String name) => _lookupMap[name];
+
+  void forEach(f(Element element)) => _lookupMap.values.forEach(f);
+
+  Iterable<Element> get values => _lookupMap.values;
+}
+
+
+abstract class AnalyzableElementMixin implements AnalyzableElement, ElementZ {
+  @override
+  bool get hasTreeElements => _unsupported('hasTreeElements');
+
+  @override
+  TreeElements get treeElements => _unsupported('treeElements');
+}
+
+
+abstract class AstElementMixin implements AstElement, ElementZ {
+  @override
+  bool get hasNode => _unsupported('hasNode');
+
+  @override
+  bool get hasResolvedAst => _unsupported('hasResolvedAst');
+
+  @override
+  get node => _unsupported('node');
+
+  @override
+  ResolvedAst get resolvedAst => _unsupported('resolvedAst');
+}
+
+abstract class ContainerMixin
+    implements DeserializedElementZ, ScopeContainerElement {
+  MappedContainer _membersMap = new MappedContainer();
+
+  @override
+  Element localLookup(String name) {
+    return _membersMap.lookup(
+        name, _decoder.getMap(Key.MEMBERS, isOptional: true));
+  }
+
+  @override
+  void forEachLocalMember(f(Element element)) {
+    MapDecoder members =
+        _decoder.getMap(Key.MEMBERS, isOptional: true);
+    if (members == null) return;
+    members.forEachKey((String key) {
+      Element member = members.getElement(key);
+      if (member != null) {
+        f(member);
+      }
+    });
+  }
+}
+
+class AbstractFieldElementZ extends ElementZ implements AbstractFieldElement {
+  final String name;
+  final FunctionElement getter;
+  final FunctionElement setter;
+
+  AbstractFieldElementZ(this.name, this.getter, this.setter);
+
+  @override
+  ElementKind get kind => ElementKind.ABSTRACT_FIELD;
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitAbstractFieldElement(this, arg);
+  }
+
+  @override
+  LibraryElement get library {
+    return getter != null ? getter.library : setter.library;
+  }
+
+  @override
+  Element get enclosingElement {
+    return getter != null ? getter.enclosingElement : setter.enclosingElement;
+  }
+
+  @override
+  SourceSpan get sourcePosition {
+    return getter != null ? getter.sourcePosition : setter.sourcePosition;
+  }
+}
+
+class LibraryElementZ extends DeserializedElementZ
+    with AnalyzableElementMixin,
+         ContainerMixin,
+         LibraryElementCommon
+    implements LibraryElement {
+  Uri _canonicalUri;
+  CompilationUnitElement _entryCompilationUnit;
+  Link<CompilationUnitElement> _compilationUnits;
+  Link<Element> _exports;
+  ListedContainer _exportsMap;
+  ListedContainer _importsMap;
+  Map<LibraryTag, LibraryElement> _libraryDependencies;
+
+  LibraryElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  @override
+  ElementKind get kind => ElementKind.LIBRARY;
+
+  @override
+  Element get enclosingElement => null;
+
+  @override
+  String get name => entryCompilationUnit.name;
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitLibraryElement(this, arg);
+  }
+
+  @override
+  LibraryElement get library => this;
+
+  @override
+  Uri get canonicalUri {
+    if (_canonicalUri == null) {
+      _canonicalUri = _decoder.getUri(Key.CANONICAL_URI);
+    }
+    return _canonicalUri;
+  }
+
+  @override
+  CompilationUnitElement get entryCompilationUnit {
+    if (_entryCompilationUnit == null) {
+      _entryCompilationUnit = _decoder.getElement(Key.COMPILATION_UNIT);
+    }
+    return _entryCompilationUnit;
+  }
+
+  @override
+  Link<CompilationUnitElement> get compilationUnits {
+    if (_compilationUnits == null) {
+      _compilationUnits =
+          toLink(_decoder.getElements(Key.COMPILATION_UNITS));
+    }
+    return _compilationUnits;
+  }
+
+  @override
+  bool hasLibraryName() {
+    return getLibraryName() != '';
+  }
+
+  @override
+  String getLibraryName() {
+    return _decoder.getString(Key.LIBRARY_NAME);
+  }
+
+  @override
+  bool get exportsHandled => true;
+
+  void _ensureExports() {
+    if (_exports == null) {
+      _exportsMap = new ListedContainer(_decoder.getElements(Key.EXPORTS));
+      _exports = toLink(_exportsMap.values);
+    }
+  }
+
+  Link<Element> get exports {
+    _ensureExports();
+    return _exports;
+  }
+
+  @override
+  void forEachExport(f(Element element)) {
+    exports.forEach(f);
+  }
+
+  @override
+  Element find(String elementName) {
+    Element element = localLookup(elementName);
+    if (element == null) {
+      _ensureImports();
+      element = _importsMap.lookup(elementName);
+    }
+    return element;
+  }
+
+  @override
+  Element findLocal(String elementName) {
+    return localLookup(elementName);
+  }
+
+  void _ensureLibraryDependencies() {
+    if (_libraryDependencies == null) {
+      _libraryDependencies = <LibraryTag, LibraryElement>{};
+      ListDecoder tags = _decoder.getList(Key.TAGS);
+      AstBuilder builder = new AstBuilder(0);
+      for (int i = 0; i < tags.length; i++) {
+        ObjectDecoder dependency = tags.getObject(i);
+        String kind = dependency.getString(Key.KIND);
+        LibraryElement library = dependency.getElement(Key.LIBRARY);
+        // TODO(johnniwinther): Add `ImportElement` and `ExportElement` to the
+        // element model to avoid hacking up nodes.
+        if (kind == 'import') {
+          Import tag = new Import(
+              builder.keywordToken('import'),
+              builder.literalString(library.canonicalUri.toString())
+                  ..getEndToken().next = builder.symbolToken(SEMICOLON_INFO),
+              null, // prefix
+              null, // combinators
+              null, // metadata
+              isDeferred: false);
+          _libraryDependencies[tag] = library;
+        } else if (kind == 'export') {
+          Export tag = new Export(
+              builder.keywordToken('export'),
+              builder.literalString(library.canonicalUri.toString())
+                  ..getEndToken().next = builder.symbolToken(SEMICOLON_INFO),
+              null,  // combinators
+              null); // metadata
+          _libraryDependencies[tag] = library;
+        }
+      }
+    }
+  }
+
+  @override
+  Iterable<LibraryTag> get tags {
+    _ensureLibraryDependencies();
+    return _libraryDependencies.keys;
+  }
+
+  LibraryElement getLibraryFromTag(LibraryDependency tag) {
+    _ensureLibraryDependencies();
+    return _libraryDependencies[tag];
+  }
+
+  @override
+  bool get canUseNative => false;
+
+  @override
+  Element findExported(String elementName) => _unsupported('findExported');
+
+  void _ensureImports() {
+    if (_importsMap == null) {
+      _importsMap = new ListedContainer(_decoder.getElements(Key.IMPORTS));
+    }
+  }
+
+  @override
+  void forEachImport(f(Element element)) {
+    _ensureImports();
+    _importsMap.forEach(f);
+  }
+
+  @override
+  Link<Import> getImportsFor(Element element) => _unsupported('getImportsFor');
+
+  @override
+  LibraryName get libraryTag => _unsupported('libraryTag');
+
+  String toString() {
+    return 'Zlibrary(${canonicalUri})';
+  }
+}
+
+class ScriptZ implements Script {
+  final Uri resourceUri;
+
+  ScriptZ(this.resourceUri);
+
+  @override
+  Script copyWithFile(SourceFile file) {
+    throw new UnsupportedError('ScriptZ.copyWithFile');
+  }
+
+  @override
+  SourceFile get file => throw new UnsupportedError('ScriptZ.file');
+
+  @override
+  bool get isSynthesized => throw new UnsupportedError('ScriptZ.isSynthesized');
+
+  @override
+  String get name => resourceUri.toString();
+
+  // TODO(johnniwinther): Support the distinction between [readableUri] and
+  // [resourceUri]; needed for platform libraries.
+  @override
+  Uri get readableUri => resourceUri;
+
+  @override
+  String get text => throw new UnsupportedError('ScriptZ.text');
+}
+
+class CompilationUnitElementZ extends DeserializedElementZ
+    with LibraryMemberMixin,
+         CompilationUnitElementCommon
+    implements CompilationUnitElement {
+  List<Element> _members;
+  Script _script;
+
+  CompilationUnitElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  @override
+  ElementKind get kind => ElementKind.COMPILATION_UNIT;
+
+  @override
+  CompilationUnitElement get compilationUnit => this;
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitCompilationUnitElement(this, arg);
+  }
+
+  @override
+  void forEachLocalMember(f(Element element)) {
+    if (_members == null) {
+      _members =
+          _decoder.getElements(Key.ELEMENTS, isOptional: true);
+    }
+    _members.forEach(f);
+  }
+
+  @override
+  Script get script {
+    if (_script == null) {
+      Uri resolvedUri = _decoder.getUri(Key.URI);
+      _script = new ScriptZ(resolvedUri);
+    }
+    return _script;
+  }
+
+  @override
+  String get name => script.name;
+}
+
+
+abstract class LibraryMemberMixin implements DeserializedElementZ {
+  LibraryElement _library;
+  CompilationUnitElement _compilationUnit;
+
+  @override
+  LibraryElement get library {
+    if (_library == null) {
+      _library = _decoder.getElement(Key.LIBRARY);
+    }
+    return _library;
+  }
+
+  @override
+  CompilationUnitElement get compilationUnit {
+    if (_compilationUnit == null) {
+      _compilationUnit = _decoder.getElement(Key.COMPILATION_UNIT);
+    }
+    return _compilationUnit;
+  }
+
+  @override
+  Element get enclosingElement => compilationUnit;
+
+  @override
+  ClassElement get enclosingClass => null;
+
+  @override
+  bool get isTopLevel => true;
+
+  @override
+  bool get isStatic => false;
+}
+
+abstract class ClassMemberMixin implements DeserializedElementZ {
+  ClassElement _class;
+
+  @override
+  Element get enclosingElement => enclosingClass;
+
+  @override
+  ClassElement get enclosingClass {
+    if (_class == null) {
+      _class = _decoder.getElement(Key.CLASS);
+    }
+    return _class;
+  }
+
+  @override
+  bool get isClassMember => true;
+
+  @override
+  LibraryElement get library => enclosingClass.library;
+
+  @override
+  CompilationUnitElement get compilationUnit => enclosingClass.compilationUnit;
+}
+
+abstract class InstanceMemberMixin implements DeserializedElementZ {
+  @override
+  bool get isTopLevel => false;
+
+  @override
+  bool get isStatic => false;
+
+  @override
+  bool get isInstanceMember => true;
+}
+
+abstract class StaticMemberMixin implements DeserializedElementZ {
+  @override
+  bool get isTopLevel => false;
+
+  @override
+  bool get isStatic => true;
+}
+
+abstract class TypedElementMixin
+    implements DeserializedElementZ, TypedElement {
+  DartType _type;
+
+  @override
+  DartType get type {
+    if (_type == null) {
+      _type = _decoder.getType(Key.TYPE);
+    }
+    return _type;
+  }
+
+  @override
+  DartType computeType(Compiler compiler) => type;
+}
+
+abstract class ParametersMixin
+    implements DeserializedElementZ, FunctionTypedElement {
+  FunctionSignature _functionSignature;
+  List<ParameterElement> _parameters;
+
+  bool get hasFunctionSignature => true;
+
+  @override
+  FunctionSignature get functionSignature {
+    if (_functionSignature == null) {
+      List<Element> requiredParameters = [];
+      List<Element> optionalParameters = [];
+      List orderedOptionalParameters = [];
+      int requiredParameterCount = 0;
+      int optionalParameterCount = 0;
+      bool optionalParametersAreNamed = false;
+      List<DartType> parameterTypes = <DartType>[];
+      List<DartType> optionalParameterTypes = <DartType>[];
+      List<String> namedParameters = <String>[];
+      List<DartType> namedParameterTypes = <DartType>[];
+      for (ParameterElement parameter in parameters) {
+        if (parameter.isOptional) {
+          optionalParameterCount++;
+          requiredParameters.add(parameter);
+          orderedOptionalParameters.add(parameter);
+          if (parameter.isNamed) {
+            optionalParametersAreNamed = true;
+            namedParameters.add(parameter.name);
+            namedParameterTypes.add(parameter.type);
+          } else {
+            optionalParameterTypes.add(parameter.type);
+          }
+        } else {
+          requiredParameterCount++;
+          optionalParameters.add(parameter);
+          parameterTypes.add(parameter.type);
+        }
+      }
+      if (optionalParametersAreNamed) {
+        orderedOptionalParameters.sort((Element a, Element b) {
+            return a.name.compareTo(b.name);
+        });
+      }
+
+      FunctionType type = new FunctionType(
+          this,
+          _decoder.getType(Key.RETURN_TYPE),
+          parameterTypes,
+          optionalParameterTypes,
+          namedParameters,
+          namedParameterTypes);
+      _functionSignature = new FunctionSignatureX(
+          requiredParameters: requiredParameters,
+          requiredParameterCount: requiredParameterCount,
+          optionalParameters: optionalParameters,
+          optionalParameterCount: optionalParameterCount,
+          optionalParametersAreNamed: optionalParametersAreNamed,
+          orderedOptionalParameters: orderedOptionalParameters,
+          type: type);
+    }
+    return _functionSignature;
+  }
+
+  List<ParameterElement> get parameters {
+    if (_parameters == null) {
+      _parameters = _decoder.getElements(Key.PARAMETERS, isOptional: true);
+    }
+    return _parameters;
+  }
+}
+
+abstract class FunctionTypedElementMixin
+    implements FunctionElement, DeserializedElementZ {
+  @override
+  AsyncMarker get asyncMarker => _unsupported('');
+
+  @override
+  bool get isExternal => _unsupported('');
+
+  @override
+  FunctionElement asFunctionElement() => this;
+}
+
+class ClassElementZ extends DeserializedElementZ
+    with AnalyzableElementMixin,
+         AstElementMixin,
+         ClassElementCommon,
+         class_members.ClassMemberMixin,
+         ContainerMixin,
+         LibraryMemberMixin,
+         TypeDeclarationMixin<InterfaceType>
+    implements ClassElement {
+  bool _isObject;
+  DartType _supertype;
+  OrderedTypeSet _allSupertypesAndSelf;
+  Link<DartType> _interfaces;
+
+  ClassElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  InterfaceType _createType(List<DartType> typeArguments) {
+    return new InterfaceType(this, typeArguments);
+  }
+
+  @override
+  ElementKind get kind => ElementKind.CLASS;
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitClassElement(this, arg);
+  }
+
+  @override
+  DartType get supertype {
+    if (_isObject == null) {
+      _supertype = _decoder.getType(Key.SUPERTYPE, isOptional: true);
+      _isObject = _supertype == null;
+    }
+    return _supertype;
+  }
+
+  @override
+  bool get isAbstract => _decoder.getBool(Key.IS_ABSTRACT);
+
+  @override
+  bool get isObject {
+    return supertype == null;
+  }
+
+  @override
+  void addBackendMember(Element element) => _unsupported('addBackendMember');
+
+  @override
+  OrderedTypeSet get allSupertypesAndSelf {
+    if (_allSupertypesAndSelf == null) {
+      ObjectDecoder supertypesDeserializer =
+          _decoder.getObject(Key.SUPERTYPES);
+      List<int> offsets = supertypesDeserializer.getInts(Key.OFFSETS);
+      List<Link<DartType>> levels = new List<Link<DartType>>(offsets.length);
+      LinkBuilder<DartType> typesBuilder = new LinkBuilder<DartType>();
+      int offset = 0;
+      int depth = offsets.length - 1;
+      for (DartType type in supertypesDeserializer.getTypes(Key.TYPES)) {
+        Link<DartType> link = typesBuilder.addLast(type);
+        if (offsets[depth] == offset) {
+          levels[depth] = link;
+          depth--;
+        }
+        offset++;
+      }
+      LinkBuilder<DartType> supertypesBuilder = new LinkBuilder<DartType>();
+      for (DartType supertype in
+          supertypesDeserializer.getTypes(Key.SUPERTYPES, isOptional: true)) {
+        supertypesBuilder.addLast(supertype);
+      }
+      Link<DartType> types = typesBuilder.toLink();
+      Link<DartType> supertypes = supertypesBuilder.toLink();
+      _allSupertypesAndSelf = new OrderedTypeSet.internal(
+          levels, types, supertypes);
+    }
+    return _allSupertypesAndSelf;
+  }
+
+  @override
+  void forEachBackendMember(void f(Element member)) {
+    _unsupported('forEachBackendMember');
+  }
+
+  @override
+  bool get hasBackendMembers => _unsupported('hasBackendMembers');
+
+  @override
+  bool get hasConstructor => _unsupported('hasConstructor');
+
+  @override
+  bool hasFieldShadowedBy(Element fieldMember) => _unsupported('');
+
+  @override
+  bool get hasIncompleteHierarchy => _unsupported('hasIncompleteHierarchy');
+
+  @override
+  bool get hasLocalScopeMembers => _unsupported('hasLocalScopeMembers');
+
+  @override
+  bool implementsFunction(Compiler compiler) {
+    return _unsupported('implementsFunction');
+  }
+
+  @override
+  Link<DartType> get interfaces {
+    if (_interfaces == null) {
+      _interfaces = toLink(
+          _decoder.getTypes(Key.INTERFACES, isOptional: true));
+    }
+    return _interfaces;
+  }
+
+  @override
+  bool get isEnumClass => false;
+
+  @override
+  bool get isProxy => _unsupported('isProxy');
+
+  @override
+  bool get isUnnamedMixinApplication {
+    return _unsupported('isUnnamedMixinApplication');
+  }
+
+  @override
+  Element lookupBackendMember(String memberName) {
+    return _unsupported('lookupBackendMember');
+  }
+
+  @override
+  ConstructorElement lookupDefaultConstructor() {
+    ConstructorElement constructor = lookupConstructor("");
+    if (constructor != null && constructor.parameters.isEmpty) {
+      return constructor;
+    }
+    return null;
+  }
+
+  @override
+  String get nativeTagInfo => _unsupported('nativeTagInfo');
+
+  @override
+  void reverseBackendMembers() => _unsupported('reverseBackendMembers');
+
+  @override
+  ClassElement get superclass => supertype != null ? supertype.element : null;
+}
+
+abstract class ConstructorElementZ extends DeserializedElementZ
+    with AnalyzableElementMixin,
+         AstElementMixin,
+         ClassMemberMixin,
+         FunctionTypedElementMixin,
+         ParametersMixin,
+         TypedElementMixin,
+         MemberElementMixin
+    implements ConstructorElement {
+  ConstantConstructor _constantConstructor;
+
+  ConstructorElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitConstructorElement(this, arg);
+  }
+
+  @override
+  bool get isConst => _decoder.getBool(Key.IS_CONST);
+
+  bool get isFromEnvironmentConstructor {
+    return name == 'fromEnvironment' &&
+           library.isDartCore &&
+           (enclosingClass.name == 'bool' ||
+            enclosingClass.name == 'int' ||
+            enclosingClass.name == 'String');
+  }
+
+  ConstantConstructor get constantConstructor {
+    if (isConst && _constantConstructor == null) {
+      ObjectDecoder data =
+          _decoder.getObject(Key.CONSTRUCTOR, isOptional: true);
+      if (data == null) {
+        assert(isFromEnvironmentConstructor);
+        return null;
+      }
+      _constantConstructor = ConstantConstructorDeserializer.deserialize(data);
+    }
+    return _constantConstructor;
+  }
+
+  @override
+  AsyncMarker get asyncMarker => _unsupported('asyncMarker');
+
+  @override
+  InterfaceType computeEffectiveTargetType(InterfaceType newType) {
+    return _unsupported('computeEffectiveTargetType');
+  }
+
+  @override
+  ConstructorElement get definingConstructor  {
+    return _unsupported('definingConstructor');
+  }
+
+  @override
+  ConstructorElement get effectiveTarget  {
+    return _unsupported('effectiveTarget');
+  }
+
+  @override
+  ConstructorElement get immediateRedirectionTarget  {
+    return _unsupported('immediateRedirectionTarget');
+  }
+
+  @override
+  bool get isExternal => _unsupported('isExternal');
+
+  @override
+  bool get isRedirectingFactory => _unsupported('isRedirectingFactory');
+
+  @override
+  bool get isRedirectingGenerative => _unsupported('isRedirectingGenerative');
+
+  @override
+  bool get isCyclicRedirection => _unsupported('isCyclicRedirection');
+
+  @override
+  PrefixElement get redirectionDeferredPrefix  {
+    return _unsupported('redirectionDeferredPrefix');
+  }
+}
+
+class GenerativeConstructorElementZ extends ConstructorElementZ {
+  GenerativeConstructorElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  @override
+  ElementKind get kind => ElementKind.GENERATIVE_CONSTRUCTOR;
+}
+
+class FactoryConstructorElementZ extends ConstructorElementZ {
+
+  FactoryConstructorElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  @override
+  ElementKind get kind => ElementKind.FUNCTION;
+
+  @override
+  bool get isFactoryConstructor => true;
+}
+
+abstract class MemberElementMixin
+    implements DeserializedElementZ, MemberElement {
+
+  @override
+  MemberElement get memberContext => this;
+
+  @override
+  Name get memberName => new Name(name, library);
+
+  @override
+  List<FunctionElement> get nestedClosures => const <FunctionElement>[];
+
+}
+
+abstract class FieldElementZ extends DeserializedElementZ
+    with AnalyzableElementMixin,
+         AstElementMixin,
+         TypedElementMixin,
+         MemberElementMixin
+    implements FieldElement {
+  ConstantExpression _constant;
+
+  FieldElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  @override
+  ElementKind get kind => ElementKind.FIELD;
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitFieldElement(this, arg);
+  }
+
+  @override
+  bool get isFinal => _decoder.getBool(Key.IS_FINAL);
+
+  @override
+  bool get isConst => _decoder.getBool(Key.IS_CONST);
+
+  @override
+  ConstantExpression get constant {
+    if (isConst && _constant == null) {
+      _constant = _decoder.getConstant(Key.CONSTANT);
+    }
+    return _constant;
+  }
+
+  @override
+  Expression get initializer => _unsupported('initializer');
+}
+
+
+class TopLevelFieldElementZ extends FieldElementZ with LibraryMemberMixin {
+  TopLevelFieldElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+class StaticFieldElementZ extends FieldElementZ
+    with ClassMemberMixin, StaticMemberMixin {
+  StaticFieldElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+class InstanceFieldElementZ extends FieldElementZ
+    with ClassMemberMixin, InstanceMemberMixin {
+  InstanceFieldElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+abstract class FunctionElementZ extends DeserializedElementZ
+    with AnalyzableElementMixin,
+         AstElementMixin,
+         ParametersMixin,
+         FunctionTypedElementMixin,
+         TypedElementMixin,
+         MemberElementMixin
+    implements MethodElement {
+  FunctionElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  @override
+  ElementKind get kind => ElementKind.FUNCTION;
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitFunctionElement(this, arg);
+  }
+
+  @override
+  bool get isOperator => _decoder.getBool(Key.IS_OPERATOR);
+}
+
+class TopLevelFunctionElementZ extends FunctionElementZ
+    with LibraryMemberMixin {
+  TopLevelFunctionElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+class StaticFunctionElementZ extends FunctionElementZ
+    with ClassMemberMixin, StaticMemberMixin {
+  StaticFunctionElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+class InstanceFunctionElementZ extends FunctionElementZ
+    with ClassMemberMixin, InstanceMemberMixin {
+  InstanceFunctionElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+abstract class GetterElementZ extends DeserializedElementZ
+    with AnalyzableElementMixin,
+         AstElementMixin,
+         FunctionTypedElementMixin,
+         ParametersMixin,
+         TypedElementMixin,
+         MemberElementMixin
+    implements FunctionElement {
+
+  GetterElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  @override
+  ElementKind get kind => ElementKind.GETTER;
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitFunctionElement(this, arg);
+  }
+}
+
+class TopLevelGetterElementZ extends GetterElementZ with LibraryMemberMixin {
+  TopLevelGetterElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+class StaticGetterElementZ extends GetterElementZ
+    with ClassMemberMixin, StaticMemberMixin {
+  StaticGetterElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+class InstanceGetterElementZ extends GetterElementZ
+    with ClassMemberMixin, InstanceMemberMixin {
+  InstanceGetterElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+abstract class SetterElementZ extends DeserializedElementZ
+    with AnalyzableElementMixin,
+         AstElementMixin,
+         FunctionTypedElementMixin,
+         ParametersMixin,
+         TypedElementMixin,
+         MemberElementMixin
+    implements FunctionElement {
+
+  SetterElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  @override
+  ElementKind get kind => ElementKind.SETTER;
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitFunctionElement(this, arg);
+  }
+}
+
+class TopLevelSetterElementZ extends SetterElementZ with LibraryMemberMixin {
+  TopLevelSetterElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+class StaticSetterElementZ extends SetterElementZ
+    with ClassMemberMixin, StaticMemberMixin {
+  StaticSetterElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+class InstanceSetterElementZ extends SetterElementZ
+    with ClassMemberMixin, InstanceMemberMixin {
+  InstanceSetterElementZ(ObjectDecoder decoder)
+      : super(decoder);
+}
+
+abstract class TypeDeclarationMixin<T extends GenericType>
+    implements DeserializedElementZ, TypeDeclarationElement {
+  List<DartType> _typeVariables;
+  T _rawType;
+  T _thisType;
+
+  void _ensureTypes() {
+    if (_typeVariables == null) {
+      _typeVariables = _decoder.getTypes(
+          Key.TYPE_VARIABLES, isOptional: true);
+      _rawType = _createType(new List<DartType>.filled(
+          _typeVariables.length, const DynamicType()));
+      _thisType = _createType(_typeVariables);
+    }
+  }
+
+  T _createType(List<DartType> typeArguments);
+
+  @override
+  List<DartType> get typeVariables {
+    _ensureTypes();
+    return _typeVariables;
+  }
+
+  @override
+  T get rawType {
+    _ensureTypes();
+    return _rawType;
+  }
+
+  @override
+  T get thisType {
+    _ensureTypes();
+    return _thisType;
+  }
+
+  @override
+  T computeType(Compiler compiler) => thisType;
+
+  @override
+  bool get isResolved => true;
+
+  @override
+  void ensureResolved(Compiler compiler) {}
+}
+
+class TypedefElementZ extends DeserializedElementZ
+    with AnalyzableElementMixin,
+         AstElementMixin,
+         LibraryMemberMixin,
+         ParametersMixin,
+         TypeDeclarationMixin<TypedefType>
+    implements TypedefElement {
+  DartType _alias;
+
+  TypedefElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  TypedefType _createType(List<DartType> typeArguments) {
+    return new TypedefType(this, typeArguments);
+  }
+
+  @override
+  ElementKind get kind => ElementKind.TYPEDEF;
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitTypedefElement(this, arg);
+  }
+
+  @override
+  DartType get alias {
+    if (_alias == null) {
+      _alias = _decoder.getType(Key.ALIAS);
+    }
+    return _alias;
+  }
+
+  @override
+  void checkCyclicReference(Compiler compiler) {}
+}
+
+class TypeVariableElementZ extends DeserializedElementZ
+    with AnalyzableElementMixin,
+         AstElementMixin,
+         TypedElementMixin
+    implements TypeVariableElement {
+  TypeDeclarationElement _typeDeclaration;
+  TypeVariableType _type;
+  DartType _bound;
+
+  TypeVariableElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  @override
+  ElementKind get kind => ElementKind.TYPE_VARIABLE;
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitTypeVariableElement(this, arg);
+  }
+
+  @override
+  CompilationUnitElement get compilationUnit {
+    return typeDeclaration.compilationUnit;
+  }
+
+  @override
+  Element get enclosingElement => typeDeclaration;
+
+  @override
+  Element get enclosingClass => typeDeclaration;
+
+  @override
+  int get index => _decoder.getInt(Key.INDEX);
+
+  @override
+  TypeDeclarationElement get typeDeclaration {
+    if (_typeDeclaration == null) {
+      _typeDeclaration =
+          _decoder.getElement(Key.TYPE_DECLARATION);
+    }
+    return _typeDeclaration;
+  }
+
+  DartType get bound {
+    if (_bound == null) {
+      _bound = _decoder.getType(Key.BOUND);
+    }
+    return _bound;
+  }
+
+  @override
+  LibraryElement get library => typeDeclaration.library;
+}
+
+class ParameterElementZ extends DeserializedElementZ
+    with AnalyzableElementMixin,
+         AstElementMixin,
+         TypedElementMixin
+    implements ParameterElement {
+  FunctionElement _functionDeclaration;
+  ConstantExpression _constant;
+  DartType _type;
+
+  ParameterElementZ(ObjectDecoder decoder) : super(decoder);
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitParameterElement(this, arg);
+  }
+
+  @override
+  ConstantExpression get constant {
+    if (isOptional) {
+      if (_constant == null) {
+        _constant = _decoder.getConstant(Key.CONSTANT);
+      }
+      return _constant;
+    }
+    return null;
+  }
+
+  @override
+  CompilationUnitElement get compilationUnit {
+    return functionDeclaration.compilationUnit;
+  }
+
+  @override
+  ExecutableElement get executableContext => functionDeclaration;
+
+  @override
+  Element get enclosingElement => functionDeclaration;
+
+  @override
+  FunctionElement get functionDeclaration {
+    if (_functionDeclaration == null) {
+      _functionDeclaration = _decoder.getElement(Key.FUNCTION);
+    }
+    return _functionDeclaration;
+  }
+
+  @override
+  FunctionSignature get functionSignature => _unsupported('functionSignature');
+
+  @override
+  Expression get initializer => _unsupported('initializer');
+
+  @override
+  bool get isNamed => _decoder.getBool(Key.IS_NAMED);
+
+  @override
+  bool get isOptional => _decoder.getBool(Key.IS_OPTIONAL);
+
+  @override
+  ElementKind get kind => ElementKind.PARAMETER;
+
+  @override
+  LibraryElement get library => executableContext.library;
+
+  @override
+  MemberElement get memberContext => executableContext.memberContext;
+}
+
+
+class InitializingFormalElementZ extends ParameterElementZ
+    implements InitializingFormalElement {
+  FieldElement _fieldElement;
+
+  InitializingFormalElementZ(ObjectDecoder decoder)
+      : super(decoder);
+
+  @override
+  FieldElement get fieldElement {
+    if (_fieldElement == null) {
+      _fieldElement = _decoder.getElement(Key.FIELD);
+    }
+    return _fieldElement;
+  }
+
+  @override
+  accept(ElementVisitor visitor, arg) {
+    return visitor.visitFieldParameterElement(this, arg);
+  }
+
+  @override
+  ElementKind get kind => ElementKind.INITIALIZING_FORMAL;
+
+}