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

sdk/lib/collection/hash_map.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 _HashMapTable<K, V> extends _HashTable<K> {
+  static const int _INITIAL_CAPACITY = 8;
+  static const int _VALUE_INDEX = 1;
+
+  _HashMapTable() : super(_INITIAL_CAPACITY);
+
+  int get _entrySize => 2;
+
+  V _value(int offset) => _table[offset + _VALUE_INDEX];
+  void _setValue(int offset, V value) { _table[offset + _VALUE_INDEX] = value; }
+
+  _copyEntry(List fromTable, int fromOffset, int toOffset) {
+    _table[toOffset + _VALUE_INDEX] = fromTable[fromOffset + _VALUE_INDEX];
+  }
+}
+
+class HashMap<K, V> implements Map<K, V> {
+  final _HashMapTable<K, V> _hashTable;
+
+  HashMap() : _hashTable = new _HashMapTable<K, V>() {
+    _hashTable._container = this;
+  }
+
+  factory HashMap.from(Map<K, V> other) {
+    return new HashMap<K, V>()..addAll(other);
+  }
+
+  bool containsKey(K key) {
+    return _hashTable._get(key) >= 0;
+  }
+
+  bool containsValue(V value) {
+    List table = _hashTable._table;
+    int entrySize = _hashTable._entrySize;
+    for (int offset = 0; offset < table.length; offset += entrySize) {
+      if (!_hashTable._isFree(table[offset]) &&
+          _hashTable._value(offset) == value) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  void addAll(Map<K, V> other) {
+    other.forEach((K key, V value) {
+      int offset = _hashTable._put(key);
+      _hashTable._setValue(offset, value);
+      _hashTable._checkCapacity();
+    });
+  }
+
+  V operator [](K key) {
+    int offset = _hashTable._get(key);
+    if (offset >= 0) return _hashTable._value(offset);
+    return null;
+  }
+
+  void operator []=(K key, V value) {
+    int offset = _hashTable._put(key);
+    _hashTable._setValue(offset, value);
+    _hashTable._checkCapacity();
+  }
+
+  V putIfAbsent(K key, V ifAbsent()) {
+    int offset = _hashTable._probeForAdd(_hashTable._hashCodeOf(key), key);
+    Object entry = _hashTable._table[offset];
+    if (!_hashTable._isFree(entry)) {
+      return _hashTable._value(offset);
+    }
+    int modificationCount = _hashTable._modificationCount;
+    V value = ifAbsent();
+    if (modificationCount == _hashTable._modificationCount) {
+      _hashTable._setKey(offset, key);
+      _hashTable._setValue(offset, value);
+      if (entry == null) {
+        _hashTable._entryCount++;
+        _hashTable._checkCapacity();
+      } else {
+        assert(identical(entry, _TOMBSTONE));
+        _hashTable._deletedCount--;
+      }
+      _hashTable._recordModification();
+    } else {
+      // The table might have changed, so we can't trust [offset] any more.
+      // Do another lookup before setting the value.
+      offset = _hashTable._put(key);
+      _hashTable._setValue(offset, value);
+      _hashTable._checkCapacity();
+    }
+    return value;
+  }
+
+  V remove(K key) {
+    int offset = _hashTable._remove(key);
+    if (offset < 0) return null;
+    V oldValue = _hashTable._value(offset);
+    _hashTable._setValue(offset, null);
+    _hashTable._checkCapacity();
+    return oldValue;
+  }
+
+  void clear() {
+    _hashTable._clear();
+  }
+
+  void forEach(void action (K key, V value)) {
+    int modificationCount = _hashTable._modificationCount;
+    List table = _hashTable._table;
+    int entrySize = _hashTable._entrySize;
+    for (int offset = 0; offset < table.length; offset += entrySize) {
+      Object entry = table[offset];
+      if (!_hashTable._isFree(entry)) {
+        K key = entry;
+        V value = _hashTable._value(offset);
+        action(key, value);
+        _hashTable._checkModification(modificationCount);
+      }
+    }
+  }
+
+  Iterable<K> get keys => new _HashTableKeyIterable<K>(_hashTable);
+  Iterable<V> get values =>
+      new _HashTableValueIterable<V>(_hashTable, _HashMapTable._VALUE_INDEX);
+
+  int get length => _hashTable._elementCount;
+
+  bool get isEmpty => _hashTable._elementCount == 0;
+
+  String toString() => Maps.mapToString(this);
+}