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

sdk/lib/collection/linked_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 _LinkedHashMapTable<K, V> extends _LinkedHashTable<K> {
+  static const int _INITIAL_CAPACITY = 8;
+  static const int _VALUE_INDEX = 3;
+
+  int get _entrySize => 4;
+
+  _LinkedHashMapTable() : super(_INITIAL_CAPACITY);
+
+  V _value(int offset) => _table[offset + _VALUE_INDEX];
+  void _setValue(int offset, V value) { _table[offset + _VALUE_INDEX] = value; }
+
+  _copyEntry(List oldTable, int fromOffset, int toOffset) {
+    _table[toOffset + _VALUE_INDEX] = oldTable[fromOffset + _VALUE_INDEX];
+  }
+}
+
+/**
+ * A hash-based map that iterates keys and values in key insertion order.
+ */
+class LinkedHashMap<K, V> implements Map<K, V> {
+  final _LinkedHashMapTable _hashTable;
+
+  LinkedHashMap() : _hashTable = new _LinkedHashMapTable<K, V>() {
+    _hashTable._container = this;
+  }
+
+  factory LinkedHashMap.from(Map<K, V> other) {
+    return new LinkedHashMap<K, V>()..addAll(other);
+  }
+
+  bool containsKey(K key) {
+    return _hashTable._get(key) >= 0;
+  }
+
+  bool containsValue(V value) {
+    int modificationCount = _hashTable._modificationCount;
+    for (int offset = _hashTable._next(_LinkedHashTable._HEAD_OFFSET);
+         offset != _LinkedHashTable._HEAD_OFFSET;
+         offset = _hashTable._next(offset)) {
+      if (_hashTable._value(offset) == value) {
+        return true;
+      }
+      // The == call may modify the table.
+      _hashTable._checkModification(modificationCount);
+    }
+    return false;
+  }
+
+  void addAll(Map<K, V> other) {
+    other.forEach((K key, V value) {
+      int offset = _hashTable._put(key);

[floitsch, 2013/02/13 15:54:06]

just use this[key] = value;

[Lasse Reichstein Nielsen, 2013/02/14 10:18:12]

Again I prefer to not use a public, overridable method as part of the
implementation of another.

+      _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();
+    _hashTable._checkModification(modificationCount);
+    if (entry == null) {
+      _hashTable._entryCount++;
+      _hashTable._checkCapacity();
+    } else {
+      assert(identical(entry, _TOMBSTONE));
+      _hashTable._deletedCount--;
+    }
+    _hashTable._setKey(offset, key);
+    _hashTable._setValue(offset, value);
+    _hashTable._linkLast(offset);
+    _hashTable._recordModification();
+    return value;
+  }
+
+  V remove(K key) {
+    int offset = _hashTable._remove(key);
+    if (offset < 0) return null;
+    Object 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;
+    for (int offset = _hashTable._next(_LinkedHashTable._HEAD_OFFSET);
+         offset != _LinkedHashTable._HEAD_OFFSET;
+         offset = _hashTable._next(offset)) {
+      action(_hashTable._key(offset), _hashTable._value(offset));
+      _hashTable._checkModification(modificationCount);
+    }
+  }
+
+  Iterable<K> get keys => new _LinkedHashTableKeyIterable<K>(_hashTable);
+  Iterable<V> get values =>
+      new _LinkedHashTableValueIterable<V>(_hashTable,
+                                           _LinkedHashMapTable._VALUE_INDEX);
+
+  int get length => _hashTable._elementCount;
+
+  bool get isEmpty => _hashTable._elementCount == 0;
+
+  String toString() => Maps.mapToString(this);
+}