Make mappedBy lazy.

sdk/lib/core/set.dart

 // Copyright (c) 2011, 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.
 
 /**
  * This class is the public interface of a set. A set is a collection
  * without duplicates.
  */
 abstract class Set<E> extends Collection<E> {
   factory Set() => new _HashSetImpl<E>();
@@ skipping 59 matching lines @@
 abstract class HashSet<E> extends Set<E> {
   factory HashSet() => new _HashSetImpl<E>();
 
   /**
    * Creates a [Set] that contains all elements of [other].
    */
   factory HashSet.from(Iterable<E> other) => new _HashSetImpl<E>.from(other);
 }
 
 
-class _HashSetImpl<E> implements HashSet<E> {
+class _HashSetImpl<E> extends Iterable<E> implements HashSet<E> {
 
   _HashSetImpl() {
     _backingMap = new _HashMapImpl<E, E>();
   }
 
   factory _HashSetImpl.from(Iterable<E> other) {
     Set<E> set = new _HashSetImpl<E>();
     for (final e in other) {
       set.add(e);
     }
@@ skipping 47 matching lines @@
       return contains(value);
     });
   }
 
   void forEach(void f(E element)) {
     _backingMap.forEach((E key, E value) {
       f(key);
     });
   }
 
-  Set mappedBy(f(E element)) {
-    Set result = new Set();
-    _backingMap.forEach((E key, E value) {
-      result.add(f(key));
-    });
-    return result;
-  }
-
-  Dynamic reduce(Dynamic initialValue,
-                 Dynamic combine(Dynamic previousValue, E element)) {
-    return Collections.reduce(this, initialValue, combine);
-  }
-
-  Set<E> where(bool f(E element)) {
-    Set<E> result = new Set<E>();
-    _backingMap.forEach((E key, E value) {
-      if (f(key)) result.add(key);
-    });
-    return result;
-  }
-
-  bool every(bool f(E element)) {
-    Collection<E> keys = _backingMap.keys;
-    return keys.every(f);
-  }
-
-  bool some(bool f(E element)) {
-    Collection<E> keys = _backingMap.keys;
-    return keys.some(f);
-  }
-
   bool get isEmpty {
     return _backingMap.isEmpty;
   }
 
   int get length {
     return _backingMap.length;
   }
 
   Iterator<E> get iterator => new _HashSetIterator<E>(this);
 
   String toString() {
     return Collections.collectionToString(this);
   }
 
-  List<E> toList() {
-    return new List<E>.from(this);
-  }
-
-  Set<E> toSet() {
-    return new Set<E>.from(this);
-  }
-
   // The map backing this set. The associations in this map are all
   // of the form element -> element. If a value is not in the map,
   // then it is not in the set.
   _HashMapImpl<E, E> _backingMap;
 }
 
 class _HashSetIterator<E> implements Iterator<E> {
 
   _HashSetIterator(_HashSetImpl<E> set)
     : _keysIterator = set._backingMap._keys.iterator;
@@ skipping 12 matching lines @@
     do {
       result = _keysIterator.moveNext();
     } while (result &&
              (_keysIterator.current == null ||
               identical(_keysIterator.current, _HashMapImpl._DELETED_KEY)));
     return result;
   }
 
   Iterator _keysIterator;
 }