Big merge from experimental to bleeding edge.

sdk/lib/_internal/compiler/implementation/mirrors/mirrors_util.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 mirrors_util;
 
 // TODO(rnystrom): Use "package:" URL (#4968).
 import 'mirrors.dart';
 
 //------------------------------------------------------------------------------
@@ skipping 35 matching lines @@
 LibraryMirror findLibrary(MemberMirror member) {
   DeclarationMirror owner = member.owner;
   if (owner is LibraryMirror) {
     return owner;
   } else if (owner is TypeMirror) {
     return owner.library;
   }
   throw new Exception('Unexpected owner: ${owner}');
 }
 
-class HierarchyIterable implements Iterable<ClassMirror> {
+class HierarchyIterable extends Iterable<ClassMirror> {
   final bool includeType;
   final ClassMirror type;
 
   HierarchyIterable(this.type, {bool includeType})
       : this.includeType = includeType;
 
-  Iterator<ClassMirror> iterator() =>
+  Iterator<ClassMirror> get iterator =>
       new HierarchyIterator(type, includeType: includeType);
 }
 
 /**
  * [HierarchyIterator] iterates through the class hierarchy of the provided
  * type.
  *
- * First is the superclass relation is traversed, skipping [Object], next the
+ * First the superclass relation is traversed, skipping [Object], next the
  * superinterface relation and finally is [Object] visited. The supertypes are
  * visited in breadth first order and a superinterface is visited more than once
  * if implemented through multiple supertypes.
  */
 class HierarchyIterator implements Iterator<ClassMirror> {
   final Queue<ClassMirror> queue = new Queue<ClassMirror>();
   ClassMirror object;
+  ClassMirror _current;
 
   HierarchyIterator(ClassMirror type, {bool includeType}) {
     if (includeType) {
       queue.add(type);
     } else {
       push(type);
     }
   }
 
   ClassMirror push(ClassMirror type) {
     if (type.superclass != null) {
       if (type.superclass.isObject) {
         object = type.superclass;
       } else {
         queue.addFirst(type.superclass);
       }
     }
     queue.addAll(type.superinterfaces);
     return type;
   }
 
-  ClassMirror next() {
-    ClassMirror type;
+  ClassMirror get current => _current;
+
+  bool moveNext() {
+    _current = null;
     if (queue.isEmpty) {
-      if (object == null) {
-        throw new StateError("No more elements");
-      }
-      type = object;
+      if (object == null) return false;
+      _current = object;
       object = null;
-      return type;
+      return true;
     } else {
-      return push(queue.removeFirst());
+      _current = push(queue.removeFirst());
+      return true;
     }
   }
-
-  bool get hasNext => !queue.isEmpty || object != null;
 }