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

sdk/lib/collection/hash_set.dart

Index: sdk/lib/collection/hash_set.dart
diff --git a/sdk/lib/collection/hash_set.dart b/sdk/lib/collection/hash_set.dart
new file mode 100644
index 0000000000000000000000000000000000000000..22fb38f6f792aeedd8d185b238bc464836816d4d
--- /dev/null
+++ b/sdk/lib/collection/hash_set.dart
@@ -0,0 +1,115 @@
+// 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> {
+  static const int _INITIAL_CAPACITY = 8;
+  final _HashTable<E> _table;
+
+  HashSet() : _table = new _HashTable(_INITIAL_CAPACITY) {
+    _table._container = this;
+  }
+
+  factory HashSet.from(Iterable<E> iterable) {
+    return new HashSet<E>()..addAll(iterable);
+  }
+
+  // Iterable.
+  Iterator<E> get iterator => new _HashTableKeyIterator<E>(_table);
+
+  bool get isEmpty => _table._elementCount == 0;
+
+  bool contains(Object object) => _table._get(object) >= 0;
+
+  // Collection.
+  void add(E element) {
+    _table._put(element);
+    _table._checkCapacity();
+  }
+
+  void addAll(Iterable<E> objects) {
+    for (E object in objects) {
+      _table._put(object);
+      _table._checkCapacity();
+    }
+  }
+
+  bool remove(Object object) {
+    int offset = _table._remove(object);
+    _table._checkCapacity();
+    return offset >= 0;
+  }
+
+  void removeAll(Iterable objectsToRemove) {
+    for (Object object in objectsToRemove) {
+      _table._remove(object);
+      _table._checkCapacity();
+    }
+  }
+
+  void retainAll(Iterable objectsToRetain) {
+    IterableMixinWorkaround.retainAll(this, objectsToRetain);
+  }
+
+  void _filterMatching(bool test(E element), bool removeMatching) {
+    int entrySize = _table._entrySize;
+    int length = _table._table.length;
+    for (int offset =  0; offset < length; offset += entrySize) {
+      Object entry = _table._table[offset];
+      if (!_table._isFree(entry)) {
+        E key = identical(entry, _NULL) ? null : entry;
+        int modificationCount = _table._modificationCount;
+        bool shouldRemove = (removeMatching == test(key));
+        _table._checkModification(modificationCount);
+        if (shouldRemove) {
+          _table._deleteEntry(offset);
+        }
+      }
+    }
+    _table._checkCapacity();
+  }
+
+  void removeMatching(bool test(E element)) {
+    _filterMatching(test, true);
+  }
+
+  void retainMatching(bool test(E element)) {
+    _filterMatching(test, false);
+  }
+
+  void clear() {
+    _table._clear();
+  }
+
+  // Set.
+  bool isSubsetOf(Collection<E> collection) {
+    Set otherSet;
+    if (collection is Set) {
+      otherSet = collection;
+    } else {
+      otherSet = collection.toSet();
+    }
+    return otherSet.containsAll(this);
+  }
+
+  bool containsAll(Collection<E> collection) {
+    for (E element in collection) {
+      if (!this.contains(element)) return false;
+    }
+    return true;
+  }
+
+  Set<E> intersection(Collection<E> other) {
+    Set<E> result = new HashSet<E>();
+    for (E element in other) {
+      if (this.contains(element)) {
+        result.add(element);
+      }
+    }
+    return result;
+  }
+
+  String toString() =>  Collections.collectionToString(this);
+}