Substitution implemented for the class hierarchy.

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 832 matching lines @@
         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;
     }
   }
 
+  /**
+   * Called to ensure that type parameters and the type of this class have been
+   * created. The bounds of the type variables are not set here but instead
+   * during resolution of the class. This split is needed to create the type
+   * of the class before it has been resolved, which in turns enables the
+   * resolution to handle cyclic dependencies as for instance imposed by default
+   * classes.
+   */
+  void ensureParametersAndType(Compiler compiler) {
+    if (type === null) {

[floitsch, 2012/07/26 11:14:40]

no need to === anymore. == is enough.

+      ClassNode node = parseNode(compiler);
+      Link<Node> parameters =
+          node.typeParameters !== null ? node.typeParameters.nodes
+                                       : const EmptyLink<TypeVariable>();
+      // Create types and elements for type variable.
+      var arguments = new LinkBuilder<Type>();
+      for (Link<Node> link = parameters; !link.isEmpty(); link = link.tail) {
+        TypeVariable typeNode = link.head;
+        SourceString variableName = typeNode.name.source;
+        TypeVariableType variableType = new TypeVariableType(variableName);
+        arguments.addLast(variableType);
+        TypeVariableElement variableElement =
+            new TypeVariableElement(variableName, this, node,
+                                    variableType);
+        variableType.element = variableElement;
+        typeParameters[variableName] = variableElement;
+      }
+      type = new InterfaceType(this, arguments.toLink());
+    }
+  }
+
   Type computeType(compiler) {
-    if (type === null) {
-      type = new InterfaceType(this);
-    }
+    ensureParametersAndType(compiler);
     return type;
   }
 
   ClassElement ensureResolved(Compiler compiler) {
     compiler.resolveClass(this);
     return this;
   }
 
   Element lookupTypeParameter(SourceString parameterName) {
     Element result = typeParameters[parameterName];
@@ skipping 316 matching lines @@
   final Node node;
   Type bound;
   Type type;
   TypeVariableElement(name, Element enclosing, this.node, this.type,
                       [this.bound])
     : super(name, ElementKind.TYPE_VARIABLE, enclosing);
   Type computeType(compiler) => type;
   Node parseNode(compiler) => node;
   toString() => "${enclosingElement.toString()}.${name.slowToString()}";
 }