Skeleton typedef type implementation

lib/compiler/implementation/typechecker.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.
 
 class TypeCheckerTask extends CompilerTask {
   TypeCheckerTask(Compiler compiler) : super(compiler);
   String get name() => "Type checker";
 
   static final bool LOG_FAILURES = false;
 
   void check(Node tree, TreeElements elements) {
     measure(() {
       Visitor visitor =
           new TypeCheckerVisitor(compiler, elements, compiler.types);
       try {
         tree.accept(visitor);
       } catch (CancelTypeCheckException e) {
         if (LOG_FAILURES) {
           // Do not warn about unimplemented features; log message instead.
           compiler.log("'${e.node}': ${e.reason}");
         }
       }
     });
   }
 }
 
 interface Type {
   SourceString get name();
   Element get element();
+
+  /**
+   * Returns the unaliased type of this type.
+   *
+   * The unaliased type of a typedef'd type is the unaliased type to which its
+   * name is bound. The unaliased version of any other type is the type itself.
+   *
+   * For example, the unaliased type of [: typedef A Func<A,B>(B b) :] is the
+   * function type [: (B) -> A :] and the unaliased type of
+   * [: Func<int,String> :] is the function type [: (String) -> int :].
+   */
+  Type unalias(Compiler compiler);
 }
 
 class TypeVariableType implements Type {
   final TypeVariableElement element;
 
   TypeVariableType(this.element);
 
   SourceString get name() => element.name;
 
-  toString() => name.slowToString();
+  Type unalias(Compiler compiler) => this;
+
+  String toString() => name.slowToString();
 }
 
 /**
  * A statement type tracks whether a statement returns or may return.
  */
 class StatementType implements Type {
   final String stringName;
   Element get element() => null;
 
   SourceString get name() => new SourceString(stringName);
 
   const StatementType(this.stringName);
 
   static final RETURNING = const StatementType('<returning>');
   static final NOT_RETURNING = const StatementType('<not returning>');
   static final MAYBE_RETURNING = const StatementType('<maybe returning>');
 
   /** Combine the information about two control-flow edges that are joined. */
   StatementType join(StatementType other) {
     return (this === other) ? this : MAYBE_RETURNING;
   }
 
+  Type unalias(Compiler compiler) => this;
+
   String toString() => stringName;
 }
 
 class VoidType implements Type {
   const VoidType(this.element);
   SourceString get name() => element.name;
   final VoidElement element;
 
-  toString() => name.slowToString();
+  Type unalias(Compiler compiler) => this;
+
+  String toString() => name.slowToString();
 }
 
 class InterfaceType implements Type {
   final Element element;
   final Link<Type> arguments;
 
   const InterfaceType(this.element,
                       [this.arguments = const EmptyLink<Type>()]);
 
   SourceString get name() => element.name;
 
-  toString() {
+  Type unalias(Compiler compiler) => this;
+
+  String toString() {
     StringBuffer sb = new StringBuffer();
     sb.add(name.slowToString());
     if (!arguments.isEmpty()) {
       sb.add('<');
       arguments.printOn(sb, ', ');
       sb.add('>');
     }
     return sb.toString();
   }
 }
 
 class FunctionType implements Type {
   final Element element;
   Type returnType;
   Link<Type> parameterTypes;
 
   FunctionType(Type this.returnType, Link<Type> this.parameterTypes,
                Element this.element);
 
-  toString() {
+  Type unalias(Compiler compiler) => this;
+
+  String toString() {
     StringBuffer sb = new StringBuffer();
     bool first = true;
     sb.add('(');
     parameterTypes.printOn(sb, ', ');
     sb.add(') -> ${returnType}');
     return sb.toString();
   }
 
   SourceString get name() => const SourceString('Function');
 
   int computeArity() {
     int arity = 0;
     parameterTypes.forEach((_) { arity++; });
     return arity;
   }
 
   void initializeFrom(FunctionType other) {
     assert(returnType === null);
     assert(parameterTypes === null);
     returnType = other.returnType;
     parameterTypes = other.parameterTypes;
   }
 }
 
+class TypedefType implements Type {
+  final TypedefElement element;
+  final Link<Type> typeArguments;
+
+  const TypedefType(this.element,
+      [this.typeArguments = const EmptyLink<Type>()]);
+
+  SourceString get name() => element.name;
+
+  Type unalias(Compiler compiler) {
+    // TODO(ahe): This should be [ensureResolved].
+    compiler.resolveTypedef(element);
+    return element.alias.unalias(compiler);
+  }
+
+  String toString() {
+    StringBuffer sb = new StringBuffer();
+    sb.add(name.slowToString());
+    if (!typeArguments.isEmpty()) {
+      sb.add('<');
+      typeArguments.printOn(sb, ', ');
+      sb.add('>');
+    }
+    return sb.toString();
+  }
+}
+
 class Types {
+  final Compiler compiler;
+  // TODO(karlklose): should we have a class Void?
   final VoidType voidType;
   final InterfaceType dynamicType;
 
-  Types(Element dynamicElement)
-    : this.with(dynamicElement, new LibraryElement(new Script(null, null)));
+  Types(Compiler compiler, Element dynamicElement)
+    : this.with(compiler, dynamicElement,
+                new LibraryElement(new Script(null, null)));
 
-  // TODO(karlklose): should we have a class Void?
-  Types.with(Element dynamicElement, LibraryElement library)
-    : voidType = new VoidType(new VoidElement(library.entryCompilationUnit)),
+  Types.with(Compiler this.compiler,
+             Element dynamicElement,
+             LibraryElement library)
+    : voidType = new VoidType(new VoidElement(library)),
       dynamicType = new InterfaceType(dynamicElement);
 
   /** Returns true if t is a subtype of s */
   bool isSubtype(Type t, Type s) {
-    if (t === s || t === dynamicType || s === dynamicType ||
-        // TODO(karlklose): Test for s.element === compiler.objectClass.
-        s.name == const SourceString('Object')) return true;
+    if (t === s ||
+        t === dynamicType ||
+        s === dynamicType ||
+        s.element === compiler.objectClass) {
+      return true;
+    }
+    t = t.unalias(compiler);
+    s = s.unalias(compiler);
+
     if (t is VoidType) {
       return false;
     } else if (t is InterfaceType) {
       if (s is !InterfaceType) return false;
       ClassElement tc = t.element;
       if (tc === s.element) return true;
       for (Link<Type> supertypes = tc.allSupertypes;
            supertypes != null && !supertypes.isEmpty();
            supertypes = supertypes.tail) {
         Type supertype = supertypes.head;
         if (supertype.element === s.element) return true;
       }
       return false;
     } else if (t is FunctionType) {
+      if (s.element === compiler.functionClass) return true;
       if (s is !FunctionType) return false;
       FunctionType tf = t;
       FunctionType sf = s;
       Link<Type> tps = tf.parameterTypes;
       Link<Type> sps = sf.parameterTypes;
       while (!tps.isEmpty() && !sps.isEmpty()) {
         if (!isAssignable(tps.head, sps.head)) return false;
         tps = tps.tail;
         sps = sps.tail;
       }
@@ skipping 613 matching lines @@
   }
 
   visitCatchBlock(CatchBlock node) {
     return unhandledStatement();
   }
 
   visitTypedef(Typedef node) {
     return unhandledStatement();
   }
 }