Implement interface types.

lib/compiler/implementation/typechecker.dart

Index: lib/compiler/implementation/typechecker.dart
diff --git a/lib/compiler/implementation/typechecker.dart b/lib/compiler/implementation/typechecker.dart
index 6f3dacc53efd2b0cb66bd92c10d575c63b3a8a22..1bc286096ee2caeb624ca49d4386761b80407b33 100644
--- a/lib/compiler/implementation/typechecker.dart
+++ b/lib/compiler/implementation/typechecker.dart
@@ -33,6 +33,8 @@ class TypeVariableType implements Type {
   final SourceString name;
   Element element;
   TypeVariableType(this.name, [this.element]);
+
+  toString() => name.toString();
 }
 
 /**
@@ -58,12 +60,29 @@ class StatementType implements Type {
   String toString() => stringName;
 }
 
-class SimpleType implements Type {
+class InterfaceType implements Type {
   final SourceString name;
-  final Element element;
+  final ClassElement element;
+  final Link<Type> arguments;
 
-  const SimpleType(SourceString this.name, Element this.element);
+  const InterfaceType(this.name, this.element, this.arguments);
+
+  toString() {
+    StringBuffer sb = new StringBuffer();
+    sb.add(name.slowToString());
+    if (!arguments.isEmpty()) {
+      sb.add('<');
+      arguments.printOn(sb);
+      sb.add('>');
+    }
+    return sb.toString();
+  }
+}
 
+// TODO(karlklose): merge into InterfaceType as a named constructor.
+class SimpleType extends InterfaceType {
+  const SimpleType(SourceString name, Element element)
+    : super(name, element, const EmptyLink<Type>());
   String toString() => name.slowToString();
 }
 
@@ -101,6 +120,7 @@ class Types {
   final SimpleType dynamicType;
 
   Types() : this.with(new LibraryElement(new Script(null, null)));
+
   Types.with(LibraryElement library)
     : voidType = new SimpleType(VOID, new ClassElement(VOID, library)),
       dynamicType = new SimpleType(DYNAMIC, new ClassElement(DYNAMIC, library));
@@ -172,9 +192,9 @@ Type lookupType(SourceString name, Compiler compiler, types) {
 class TypeCheckerVisitor implements Visitor<Type> {
   final Compiler compiler;
   final TreeElements elements;
-  Node lastSeenNode;
   final Types types;
 
+  Node lastSeenNode;
   Type expectedReturnType;
   ClassElement currentClass;
 
@@ -187,8 +207,7 @@ class TypeCheckerVisitor implements Visitor<Type> {
   Type objectType;
   Type listType;
 
-  TypeCheckerVisitor(Compiler this.compiler, TreeElements this.elements,
-                     Types this.types) {
+  TypeCheckerVisitor(this.compiler, this.elements, this.types) {
     intType = lookupType(Types.INT, compiler, types);
     doubleType = lookupType(Types.DOUBLE, compiler, types);
     boolType = lookupType(Types.BOOL, compiler, types);
@@ -456,19 +475,19 @@ class TypeCheckerVisitor implements Visitor<Type> {
       FunctionType computeFunType() {
         if (node.receiver !== null) {
           Type receiverType = analyze(node.receiver);
-          if (receiverType === types.dynamicType) return null;
-            if (receiverType === null) {
-              fail(node.receiver, 'receivertype is null');
-            }
-            if (receiverType.element.kind !== ElementKind.CLASS) {
-              fail(node.receiver, 'receivertype is not a class');
-            }
-            ClassElement classElement = receiverType.element;
-            // TODO(karlklose): substitute type arguments.
-            Type memberType =
-              lookupMethodType(selector, classElement, selector.source);
-            if (memberType === types.dynamicType) return null;
-            return memberType;
+          if (receiverType.element == compiler.dynamicClass) return null;
+          if (receiverType === null) {
+            fail(node.receiver, 'receivertype is null');
+          }
+          if (receiverType.element.kind !== ElementKind.CLASS) {
+            fail(node.receiver, 'receivertype is not a class');
+          }
+          ClassElement classElement = receiverType.element;
+          // TODO(karlklose): substitute type arguments.
+          Type memberType =
+            lookupMethodType(selector, classElement, selector.source);
+          if (memberType.element === compiler.dynamicClass) return null;
+          return memberType;
         } else {
           Element element = elements[node];
           if (element === null) {