Unify ClassElement and TypedefElement.

lib/compiler/implementation/elements/elements.dart

 // 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('elements');
 
 #import('../tree/tree.dart');
 #import('../scanner/scannerlib.dart');
 #import('../leg.dart');  // TODO(karlklose): we only need type.
 #import('../util/util.dart');
@@ skipping 413 matching lines @@
     return super.getCompilationUnit();
   }
 
   lookupLocalMember(SourceString memberName) => imported[memberName];
 
   Type computeType(Compiler compiler) => compiler.types.dynamicType;
 
   Token position() => firstPosition;
 }
 
-class TypedefElement extends Element {
+class TypedefElement extends Element implements TypeDeclarationElement {
   Type cachedType;
   Typedef cachedNode;
 
   TypedefElement(SourceString name, Element enclosing)
       : super(name, ElementKind.TYPEDEF, enclosing);
 
   Type computeType(Compiler compiler) {
     if (cachedType !== null) return cachedType;
     cachedType = compiler.computeFunctionType(
         this, compiler.resolveTypedef(this));
     return cachedType;
   }
+
+  Link<Type> get typeVariables() => const EmptyLink<Type>();
+
+  Scope buildScope() =>
+      new TypeDeclarationScope(enclosingElement.buildScope(), this);
 }
 
 class VariableElement extends Element {
   final VariableListElement variables;
   Expression cachedNode; // The send or the identifier in the variables list.
 
   Modifiers get modifiers() => variables.modifiers;
 
   VariableElement(SourceString name,
                   VariableListElement this.variables,
@@ skipping 362 matching lines @@
 class VoidElement extends Element {
   VoidElement(Element enclosing)
       : super(const SourceString('void'), ElementKind.VOID, enclosing);
   Type computeType(compiler) => compiler.types.voidType;
   Node parseNode(_) {
     throw 'internal error: parseNode on void';
   }
   bool impliesType() => true;
 }
 
-class ClassElement extends ContainerElement {
+/**
+ * [TypeDeclarationElement] defines the common interface for class/interface
+ * declarations and typedefs.
+ */
+abstract class TypeDeclarationElement implements Element {
+  // TODO(johnniwinther): This class should eventually be a mixin.
+
+  /**
+   * The type variables declared on this declaration. The type variables are not
+   * available until the type of the element has been computed through
+   * [computeType].
+   */
+  // TODO(johnniwinther): Find a (better) way to decouple [typeVariables] from
+  // [Compiler].
+  final Link<Type> typeVariables;
+
+  /**
+   * Creates the type variables, their type and corresponding element, for the
+   * type variables declared in [parameter] on [element]. The bounds of the type
+   * variables are not set until [element] has been resolved.
+   */
+  static Link<Type> createTypeVariables(TypeDeclarationElement element,
+                                        NodeList parameters) {
+    if (parameters === null) return const EmptyLink<Type>();
+
+    // Create types and elements for type variable.
+    var arguments = new LinkBuilder<Type>();
+    for (Link<Node> link = parameters.nodes; !link.isEmpty(); link = link.tail) {
+      TypeVariable node = link.head;
+      SourceString variableName = node.name.source;
+      TypeVariableElement variableElement =
+          new TypeVariableElement(variableName, element, node);
+      TypeVariableType variableType = new TypeVariableType(variableElement);
+      variableElement.type = variableType;
+      arguments.addLast(variableType);
+    }
+    return arguments.toLink();
+  }
+}
+
+class ClassElement extends ContainerElement
+    implements TypeDeclarationElement {
   final int id;
-  Type type;
+  InterfaceType type;
   Type supertype;
   Type defaultClass;
   Link<Element> members = const EmptyLink<Element>();
   Map<SourceString, Element> localMembers;
   Map<SourceString, Element> constructors;
   Link<Type> interfaces = const EmptyLink<Type>();
-  LinkedHashMap<SourceString, TypeVariableElement> typeParameters;
   bool isResolved = false;
   bool isBeingResolved = false;
   // backendMembers are members that have been added by the backend to simplify
   // compilation. They don't have any user-side counter-part.
   Link<Element> backendMembers = const EmptyLink<Element>();
 
   Link<Type> allSupertypes;
   ClassElement patch = null;
 
   ClassElement(SourceString name, CompilationUnitElement enclosing, this.id)
     : localMembers = new Map<SourceString, Element>(),
       constructors = new Map<SourceString, Element>(),
-      typeParameters = new LinkedHashMap<SourceString, TypeVariableElement>(),
       super(name, ElementKind.CLASS, enclosing);
 
   void addMember(Element element, DiagnosticListener listener) {
     members = members.prepend(element);
     if (element.kind == ElementKind.GENERATIVE_CONSTRUCTOR ||
         element.modifiers.isFactory()) {
       constructors[element.name] = element;
     } else if (element.kind == ElementKind.GETTER
                || element.kind == ElementKind.SETTER) {
       addGetterOrSetter(element, localMembers[element.name], listener);
     } else {
       localMembers[element.name] = element;
     }
   }
 
-  Type computeType(compiler) {
-    if (type === null) {
-      type = new InterfaceType(this);
+  InterfaceType computeType(compiler) {
+    if (type == null) {
+      ClassNode node = parseNode(compiler);
+      Link<Type> parameters =
+          TypeDeclarationElement.createTypeVariables(this, node.typeParameters);
+      type = new InterfaceType(this, parameters);
     }
     return type;
   }
 
+  Link<Type> get typeVariables() => type.arguments;
+
   ClassElement ensureResolved(Compiler compiler) {
     compiler.resolveClass(this);
     return this;
   }
 
-  Element lookupTypeParameter(SourceString parameterName) {
-    Element result = typeParameters[parameterName];
-    return result;
-  }
-
   Element lookupLocalMember(SourceString memberName) {
     return localMembers[memberName];
   }
 
   Element lookupSuperMember(SourceString memberName) {
     for (ClassElement s = superclass; s != null; s = s.superclass) {
       Element e = s.lookupLocalMember(memberName);
       if (e === null) continue;
       // Private members from a different library are not visible.
       if (memberName.isPrivate() && getLibrary() !== e.getLibrary()) continue;
@@ skipping 296 matching lines @@
 
   Node parseNode(DiagnosticListener l) => statement;
 
   bool get isSwitch() => statement is SwitchStatement;
 
   Token position() => statement.getBeginToken();
   String toString() => statement.toString();
 }
 
 class TypeVariableElement extends Element {
-  final Node node;
+  final Node cachedNode;
+  TypeVariableType type;
   Type bound;
-  Type type;
-  TypeVariableElement(name, Element enclosing, this.node, this.type,
-                      [this.bound])
+
+  TypeVariableElement(name, Element enclosing, this.cachedNode,
+                      [this.type, this.bound])
     : super(name, ElementKind.TYPE_VARIABLE, enclosing);
-  Type computeType(compiler) => type;
-  Node parseNode(compiler) => node;
-  toString() => "${enclosingElement.toString()}.${name.slowToString()}";
+
+  TypeVariableType computeType(compiler) => type;
+
+  Node parseNode(compiler) => cachedNode;
+
+  String toString() => "${enclosingElement.toString()}.${name.slowToString()}";
 }