Convert HashSet, LinkedHashSet to factory methods and custom implementations.

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;
 
 /**
  * A [LinkedHashSet] is a hash-table based [Set] implementation.
  *
  * The `LinkedHashSet` also keep track of the order that elements were inserted
  * in, and iteration happens in first-to-last insertion order.
  *
  * The elements of a `LinkedHashSet` must have consistent [Object.operator==]
  * and [Object.hashCode] implementations. This means that the `==` operator
  * must define a stable equivalence relation on the elements (reflexive,
  * anti-symmetric, transitive, and consistent over time), and that `hashCode`
  * must be the same for objects that are considered equal by `==`.
  *
  * The set allows `null` as an element.
  *
  * Most simple operations on `HashSet` are done in constant time: [add],
  * [contains], [remove], and [length].
  */
-class LinkedHashSet<E> extends _HashSetBase<E> {
+class LinkedHashSet<E> implements HashSet<E> {
 
-  external LinkedHashSet();
+  external factory LinkedHashSet({ bool equals(E e1, E e2),
+                                   int hashCode(E e),
+                                   bool isValidKey(potentialKey) });
 
   factory LinkedHashSet.from(Iterable<E> iterable) {
     return new LinkedHashSet<E>()..addAll(iterable);
   }
-
-  // Iterable.
-
-  /** Return an iterator that iterates over elements in insertion order. */
-  external Iterator<E> get iterator;
-
-  external int get length;
-
-  external bool get isEmpty;
-
-  external bool get isNotEmpty;
-
-  external bool contains(Object object);
-
-  /** Perform an operation on each element in insertion order. */
-  external void forEach(void action(E element));
-
-  external E get first;
-
-  external E get last;
-
-  E get single {
-    if (length == 1) return first;
-    var message = (length == 0) ? "No Elements" : "Too many elements";
-    throw new StateError(message);
-  }
-
-  // Collection.
-  external void add(E element);
-
-  external void addAll(Iterable<E> objects);
-
-  external bool remove(Object object);
-
-  external void removeAll(Iterable objectsToRemove);
-
-  external void removeWhere(bool test(E element));
-
-  external void retainWhere(bool test(E element));
-
-  external void clear();
-
-  // Set.
-  Set<E> _newSet() => new LinkedHashSet<E>();
 }