Make mappedBy lazy.

sdk/lib/core/queue.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.
 
 /**
  * A [Queue] is a collection that can be manipulated at both ends. One
  * can iterate over the elements of a queue through [forEach] or with
  * an [Iterator].
  */
 abstract class Queue<E> extends Collection<E> {
@@ skipping 152 matching lines @@
   }
 }
 
 /**
  * Implementation of a double linked list that box list elements into
  * DoubleLinkedQueueEntry objects.
  *
  * WARNING: This class is temporary located in dart:core. It'll be removed
  * at some point in the near future.
  */
-class DoubleLinkedQueue<E> implements Queue<E> {
+class DoubleLinkedQueue<E> extends Iterable<E> implements Queue<E> {
   _DoubleLinkedQueueEntrySentinel<E> _sentinel;
 
   DoubleLinkedQueue() {
     _sentinel = new _DoubleLinkedQueueEntrySentinel<E>();
   }
 
   factory DoubleLinkedQueue.from(Iterable<E> other) {
     Queue<E> list = new DoubleLinkedQueue();
     for (final e in other) {
       list.addLast(e);
@@ skipping 36 matching lines @@
   }
 
   DoubleLinkedQueueEntry<E> lastEntry() {
     return _sentinel.previousEntry();
   }
 
   DoubleLinkedQueueEntry<E> firstEntry() {
     return _sentinel.nextEntry();
   }
 
-  int get length {
-    int counter = 0;
-    forEach((E element) { counter++; });
-    return counter;
-  }
-
   bool get isEmpty {
     return (identical(_sentinel._next, _sentinel));
   }
 
   void clear() {
     _sentinel._next = _sentinel;
     _sentinel._previous = _sentinel;
   }
 
-  void forEach(void f(E element)) {
-    DoubleLinkedQueueEntry<E> entry = _sentinel._next;
-    while (!identical(entry, _sentinel)) {
-      DoubleLinkedQueueEntry<E> nextEntry = entry._next;
-      f(entry._element);
-      entry = nextEntry;
-    }
-  }
-
   void forEachEntry(void f(DoubleLinkedQueueEntry<E> element)) {
     DoubleLinkedQueueEntry<E> entry = _sentinel._next;
     while (!identical(entry, _sentinel)) {
       DoubleLinkedQueueEntry<E> nextEntry = entry._next;
       f(entry);
       entry = nextEntry;
     }
   }
 
-  bool every(bool f(E element)) {
-    DoubleLinkedQueueEntry<E> entry = _sentinel._next;
-    while (!identical(entry, _sentinel)) {
-      DoubleLinkedQueueEntry<E> nextEntry = entry._next;
-      if (!f(entry._element)) return false;
-      entry = nextEntry;
-    }
-    return true;
-  }
-
-  bool some(bool f(E element)) {
-    DoubleLinkedQueueEntry<E> entry = _sentinel._next;
-    while (!identical(entry, _sentinel)) {
-      DoubleLinkedQueueEntry<E> nextEntry = entry._next;
-      if (f(entry._element)) return true;
-      entry = nextEntry;
-    }
-    return false;
-  }
-
-  Queue mappedBy(f(E element)) {
-    Queue other = new Queue();
-    DoubleLinkedQueueEntry<E> entry = _sentinel._next;
-    while (!identical(entry, _sentinel)) {
-      DoubleLinkedQueueEntry<E> nextEntry = entry._next;
-      other.addLast(f(entry._element));
-      entry = nextEntry;
-    }
-    return other;
-  }
-
-  Dynamic reduce(Dynamic initialValue,
-                 Dynamic combine(Dynamic previousValue, E element)) {
-    return Collections.reduce(this, initialValue, combine);
-  }
-
-  Queue<E> where(bool f(E element)) {
-    Queue<E> other = new Queue<E>();
-    DoubleLinkedQueueEntry<E> entry = _sentinel._next;
-    while (!identical(entry, _sentinel)) {
-      DoubleLinkedQueueEntry<E> nextEntry = entry._next;
-      if (f(entry._element)) other.addLast(entry._element);
-      entry = nextEntry;
-    }
-    return other;
-  }
-
   _DoubleLinkedQueueIterator<E> get iterator {
     return new _DoubleLinkedQueueIterator<E>(_sentinel);
   }
 
   String toString() {
     return Collections.collectionToString(this);
   }
 }
 
 class _DoubleLinkedQueueIterator<E> implements Iterator<E> {
@@ skipping 12 matching lines @@
   }
 
   E get current {
     if (_currentEntry != null && !identical(_currentEntry, _sentinel)) {
       return _currentEntry.element;
     }
     // TODO(floitsch): adapt error message.
     throw new StateError("No more elements");
   }
 }