VM-internalize the default Map implementation.

runtime/lib/linked_hash_map.dart

-// Copyright (c) 2014, 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.
-
-// VM-internalized implementation of a default-constructed LinkedHashMap.
-// Currently calls the runtime for most operations.
-class _InternalLinkedHashMap<K, V> implements HashMap<K, V>,
-                                              LinkedHashMap<K, V> {
-  factory _InternalLinkedHashMap() native "LinkedHashMap_allocate";
-  int get length native "LinkedHashMap_getLength";
-  V operator [](K key) native "LinkedHashMap_lookUp";
-  void operator []=(K key, V value) native "LinkedHashMap_insertOrUpdate";
-  V remove(K key) native "LinkedHashMap_remove";
-  void clear() native "LinkedHashMap_clear";
-  bool containsKey(K key) native "LinkedHashMap_containsKey";
-
-  bool get isEmpty => length == 0;
-  bool get isNotEmpty => !isEmpty;
-
-  List _toArray() native "LinkedHashMap_toArray";
-
-  // "Modificaton marks" are tokens used to detect concurrent modification.
-  // Considering only modifications (M) and iterator creation (I) events, e.g.:
-  //   M, M, M, I, I, M, I, M, M, I, I, I, M ...
-  // a new mark is allocated at the start of each run of I's and cleared from
-  // the map at the start of each run of M's. Iterators' moveNext check whether
-  // the map's mark was changed or cleared since the iterator was created.
-  // TODO(koda): Consider a counter instead.
-  Object _getModMark(bool create) native "LinkedHashMap_getModMark";
-
-  void addAll(Map<K, V> other) {
-    other.forEach((K key, V value) {
-      this[key] = value;
-    });
-  }
-
-  V putIfAbsent(K key, Function ifAbsent) {
-    if (containsKey(key)) {
-      return this[key];
-    } else {
-      V value = ifAbsent();
-      this[key] = value;
-      return value;
-    }
-  }
-
-  bool containsValue(V value) {
-    for (V v in values) {
-      if (v == value) {
-        return true;
-      }
-    }
-    return false;
-  }
-
-  void forEach(Function f) {
-    for (K key in keys) {
-      f(key, this[key]);
-    }
-  }
-
-  // The even-indexed entries of toArray are the keys.
-  Iterable<K> get keys =>
-      new _ListStepIterable<K>(this, _getModMark(true), _toArray(), -2, 2);
-
-  // The odd-indexed entries of toArray are the values.
-  Iterable<V> get values =>
-      new _ListStepIterable<V>(this, _getModMark(true), _toArray(), -1, 2);
-
-  String toString() => Maps.mapToString(this);
-}
-
-// Iterates over a list from a given offset and step size.
-class _ListStepIterable<E> extends IterableBase<E> {
-  _InternalLinkedHashMap _map;
-  Object _modMark;
-  List _list;
-  int _offset;
-  int _step;
-
-  _ListStepIterable(this._map, this._modMark,
-                    this._list, this._offset, this._step);
-
-  Iterator<E> get iterator =>
-      new _ListStepIterator(_map, _modMark, _list, _offset, _step);
-
-  // TODO(koda): Should this check for concurrent modification?
-  int get length => _map.length;
-  bool get isEmpty => length == 0;
-  bool get isNotEmpty => !isEmpty;
-}
-
-class _ListStepIterator<E> implements Iterator<E> {
-  _InternalLinkedHashMap _map;
-  Object _modMark;
-  List _list;
-  int _offset;
-  int _step;
-
-  _ListStepIterator(this._map, this._modMark,
-                    this._list, this._offset, this._step);
-
-  bool moveNext() {
-    if (_map._getModMark(false) != _modMark) {
-      throw new ConcurrentModificationError(_map);
-    }
-    _offset += _step;
-    return _offset < _list.length;
-  }
-
-  E get current {
-    if (_offset < 0 || _offset >= _list.length) {
-      return null;
-    }
-    return _list[_offset];
-  }
-}
-