Revert "Reapply "New implementation of {,Linked}Hash{Set,Map}.""

sdk/lib/collection/set.dart

Index: sdk/lib/collection/set.dart
diff --git a/sdk/lib/collection/set.dart b/sdk/lib/collection/set.dart
new file mode 100644
index 0000000000000000000000000000000000000000..9363676e867eccee06f9a299397fb50a0c97806d
--- /dev/null
+++ b/sdk/lib/collection/set.dart
@@ -0,0 +1,110 @@
+// 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 HashSet<E> extends Collection<E> implements Set<E> {
+  // 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.
+  final _HashMapImpl<E, E> _backingMap;
+
+  HashSet() : _backingMap = new _HashMapImpl<E, E>();
+
+  /**
+   * Creates a [Set] that contains all elements of [other].
+   */
+  factory HashSet.from(Iterable<E> other) {
+    Set<E> set = new HashSet<E>();
+    for (final e in other) {
+      set.add(e);
+    }
+    return set;
+  }
+
+  void clear() {
+    _backingMap.clear();
+  }
+
+  void add(E value) {
+    _backingMap[value] = value;
+  }
+
+  bool remove(Object value) {
+    if (!_backingMap.containsKey(value)) return false;
+    _backingMap.remove(value);
+    return true;
+  }
+
+  bool contains(E value) {
+    return _backingMap.containsKey(value);
+  }
+
+  Set<E> intersection(Collection<E> collection) {
+    Set<E> result = new Set<E>();
+    collection.forEach((E value) {
+      if (contains(value)) result.add(value);
+    });
+    return result;
+  }
+
+  bool isSubsetOf(Collection<E> other) {
+    return new Set<E>.from(other).containsAll(this);
+  }
+
+  bool containsAll(Collection<E> collection) {
+    return collection.every((E value) {
+      return contains(value);
+    });
+  }
+
+  void forEach(void f(E element)) {
+    _backingMap.forEach((E key, E value) {
+      f(key);
+    });
+  }
+
+  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);
+  }
+}
+
+class _HashSetIterator<E> implements Iterator<E> {
+
+  _HashSetIterator(HashSet<E> set)
+    : _keysIterator = set._backingMap._keys.iterator;
+
+  E get current {
+    var result = _keysIterator.current;
+    if (identical(result, _HashMapImpl._DELETED_KEY)) {
+      // TODO(floitsch): improve the error reporting.
+      throw new StateError("Concurrent modification.");
+    }
+    return result;
+  }
+
+  bool moveNext() {
+    bool result;
+    do {
+      result = _keysIterator.moveNext();
+    } while (result &&
+             (_keysIterator.current == null ||
+              identical(_keysIterator.current, _HashMapImpl._DELETED_KEY)));
+    return result;
+  }
+
+  Iterator _keysIterator;
+}