Implement JS version of LinkedHashSet and move the various HashTable implementations to the VM coll…

sdk/lib/collection/linked_hash_set.dart

 // Copyright (c) 2013, 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.
 
 part of dart.collection;
 
 class LinkedHashSet<E> extends _HashSetBase<E> {
-  static const int _INITIAL_CAPACITY = 8;
-  _LinkedHashTable<E> _table;
 
-  LinkedHashSet() : _table = new _LinkedHashTable(_INITIAL_CAPACITY) {
-    _table._container = this;
-  }
+  external LinkedHashSet();
 
   factory LinkedHashSet.from(Iterable<E> iterable) {
     return new LinkedHashSet<E>()..addAll(iterable);
   }
 
   // Iterable.
-  Iterator<E> get iterator => new _LinkedHashTableKeyIterator<E>(_table);
+  external Iterator<E> get iterator;
 
-  int get length => _table._elementCount;
+  external int get length;
 
-  bool get isEmpty => _table._elementCount == 0;
+  external bool get isEmpty;
 
-  bool contains(Object object) => _table._get(object) >= 0;
+  external bool contains(Object object);
 
-  void forEach(void action(E element)) {
-    int offset = _table._next(_LinkedHashTable._HEAD_OFFSET);
-    int modificationCount = _table._modificationCount;
-    while (offset != _LinkedHashTable._HEAD_OFFSET) {
-      E key = _table._key(offset);
-      action(key);
-      _table._checkModification(modificationCount);
-      offset = _table._next(offset);
-    }
-  }
+  external void forEach(void action(E element));
 
-  E get first {
-    int firstOffset = _table._next(_LinkedHashTable._HEAD_OFFSET);
-    if (firstOffset == _LinkedHashTable._HEAD_OFFSET) {
-      throw new StateError("No elements");
-    }
-    return _table._key(firstOffset);
-  }
+  external E get first;
 
-  E get last {
-    int lastOffset = _table._prev(_LinkedHashTable._HEAD_OFFSET);
-    if (lastOffset == _LinkedHashTable._HEAD_OFFSET) {
-      throw new StateError("No elements");
-    }
-    return _table._key(lastOffset);
-  }
+  external E get last;
 
   E get single {
-    int firstOffset = _table._next(_LinkedHashTable._HEAD_OFFSET);
-    if (firstOffset == _LinkedHashTable._HEAD_OFFSET) {
-      throw new StateError("No elements");
-    }
-    int lastOffset = _table._prev(_LinkedHashTable._HEAD_OFFSET);
-    if (lastOffset != firstOffset) {
-      throw new StateError("Too many elements");
-    }
-    return _table._key(firstOffset);
+    if (length == 1) return first;
+    var message = (length == 0) ? "No Elements" : "Too many elements";
+    throw new StateError(message);
   }
 
   // Collection.
-  void _filterWhere(bool test(E element), bool removeMatching) {
-    int entrySize = _table._entrySize;
-    int length = _table._table.length;
-    int offset = _table._next(_LinkedHashTable._HEAD_OFFSET);
-    while (offset != _LinkedHashTable._HEAD_OFFSET) {
-      E key = _table._key(offset);
-      int nextOffset = _table._next(offset);
-      int modificationCount = _table._modificationCount;
-      bool shouldRemove = (removeMatching == test(key));
-      _table._checkModification(modificationCount);
-      if (shouldRemove) {
-        _table._deleteEntry(offset);
-      }
-      offset = nextOffset;
-    }
-    _table._checkCapacity();
-  }
+  external void add(E element);
 
-  void add(E element) {
-    _table._put(element);
-    _table._checkCapacity();
-  }
+  external void addAll(Iterable<E> objects);
 
-  bool remove(Object object) {
-    int offset = _table._remove(object);
-    if (offset >= 0) {
-      _table._checkCapacity();
-      return true;
-    }
-    return false;
-  }
+  external bool remove(Object object);
 
-  void removeAll(Iterable objectsToRemove) {
-    for (Object object in objectsToRemove) {
-      if (_table._remove(object) >= 0) {
-        _table._checkCapacity();
-      }
-    }
-  }
+  external void removeAll(Iterable objectsToRemove);
 
-  void retainAll(Iterable objectsToRetain) {
-    Set retainSet;
-    if (objectsToRetain is Set) {
-      retainSet = objectsToRetain;
-    } else {
-      retainSet = objectsToRetain.toSet();
-    }
-    _filterWhere(retainSet.contains, false);
-  }
+  external void removeWhere(bool test(E element));
 
-  void removeWhere(bool test(E element)) {
-    _filterWhere(test, true);
-  }
+  external void retainWhere(bool test(E element));
 
-  retianWhere(bool test(E element)) {
-    _filterWhere(test, false);
-  }
+  external void clear();
 
-  // Set
+  // Set.
   Set<E> _newSet() => new LinkedHashSet<E>();
 }