Start supporting default classes.

dart/frog/leg/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
 }
 
 class TreeElementMapping implements TreeElements {
@@ skipping 782 matching lines @@
     visit(node.condition);
     visitLoopBodyIn(node, node.body, new BlockScope(context));
   }
 
   visitParenthesizedExpression(ParenthesizedExpression node) {
     visit(node.expression);
   }
 
   visitNewExpression(NewExpression node) {
     if (node.isConst()) cancel(node, 'const expressions are not implemented');
-    if (node.send.selector.asTypeAnnotation() === null) {
+    Node selector = node.send.selector;
+    if (selector.asTypeAnnotation() === null) {
       cancel(
           node, 'named constructors with type arguments are not implemented');
     }
 
     SourceString constructorName;
-    Node typeName = node.send.selector.asTypeAnnotation().typeName;
+    Node typeName = selector.asTypeAnnotation().typeName;
     if (typeName.asSend() !== null) {
       Identifier receiver = typeName.asSend().receiver.asIdentifier();
       Identifier selector = typeName.asSend().selector.asIdentifier();
       SourceString className = receiver.source;
       SourceString name = selector.source;
       constructorName = Elements.constructConstructorName(className, name);
     } else {
       constructorName = typeName.asIdentifier().source;
     }
-    ClassElement cls = resolveTypeRequired(node.send.selector);
+    ClassElement cls = resolveTypeRequired(selector);
     Element constructor = null;
     if (cls !== null) {
-      constructor = cls.resolve(compiler).lookupConstructor(constructorName);
+      cls.resolve(compiler);
+      if (cls.isInterface() && (cls.defaultClass === null)) {
+        error(selector, MessageKind.CANNOT_INSTANTIATE_INTERFACE, [cls.name]);
+      }
+      constructor = cls.lookupConstructor(constructorName);
       if (constructorName == cls.name
           && constructor === null
           && node.send.argumentsNode.isEmpty()) {
         constructor = cls.getSynthesizedConstructor();
       }
       if (constructor === null) {
         error(node.send, MessageKind.CANNOT_FIND_CONSTRUCTOR, [node.send]);
       } else {
         FunctionElement function = constructor;
         // TODO(karlklose): handle optional arguments.
         if (node.send.argumentCount() != function.parameterCount(compiler)) {
           // TODO(ngeoffray): reslution error with wrong number of
           // parameters. We cannot do this rigth now because of the
           // List constructor.
         }
       }
     } else {
-      Node selector = node.send.selector;
       error(selector, MessageKind.CANNOT_RESOLVE_TYPE, [selector]);
     }
     handleArguments(node.send);
     useElement(node.send, constructor);
     return null;
   }
 
   ClassElement resolveTypeRequired(Node node) {
     bool old = typeRequired;
     typeRequired = true;
@@ skipping 166 matching lines @@
     if (element.name != Types.OBJECT && element.supertype === null) {
       ClassElement objectElement = context.lookup(Types.OBJECT);
       if (objectElement !== null && !objectElement.isResolved) {
         compiler.resolver.toResolve.add(objectElement);
       } else if (objectElement === null){
         error(node, MessageKind.CANNOT_RESOLVE_TYPE, [Types.OBJECT]);
       }
       element.supertype = new SimpleType(Types.OBJECT,
                                          objectElement);
     }
+    if (node.defaultClause !== null) {
+      element.defaultClass = visit(node.defaultClause.nodes.head);
+    }
     for (Link<Node> link = node.interfaces.nodes;
          !link.isEmpty();
          link = link.tail) {
       element.interfaces = element.interfaces.prepend(visit(link.head));
     }
     return element.computeType(compiler);
   }
 
   Type visitTypeAnnotation(TypeAnnotation node) {
     Identifier name = node.typeName.asIdentifier();
     if (name === null) {
       unimplemented(node.typeName, "prefixes");
     }
-    Element element = context.lookup(name.source);
+    return visit(name);
+  }
+
+  Type visitIdentifier(Identifier node) {
+    Element element = context.lookup(node.source);
     if (element === null) {
-      error(node, MessageKind.CANNOT_RESOLVE_TYPE, [name]);
+      error(node, MessageKind.CANNOT_RESOLVE_TYPE, [node]);
     } else if (element.kind !== ElementKind.CLASS) {
-      error(node, MessageKind.NOT_A_TYPE, [name]);
+      error(node, MessageKind.NOT_A_TYPE, [node]);
     } else {
       compiler.resolver.toResolve.add(element);
       // TODO(ngeoffray): Use type variables.
       return element.computeType(compiler);
     }
     return null;
   }
 }
 
 class VariableDefinitionsVisitor extends CommonResolverVisitor<SourceString> {
@@ skipping 226 matching lines @@
 class TopScope extends Scope {
   LibraryElement get library() => element;
 
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) => library.find(name);
 
   Element add(Element element) {
     throw "Cannot add an element in the top scope";
   }
 }