| // Copyright (c) 2012, 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; |
| |
| /* |
| * Helper class which implements complex [Map] operations |
| * in term of basic ones ([Map.keys], [Map.operator []], |
| * [Map.operator []=] and [Map.remove].) Not all methods are |
| * necessary to implement each particular operation. |
| */ |
| class Maps { |
| static bool containsValue(Map map, value) { |
| for (final v in map.values) { |
| if (value == v) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| static bool containsKey(Map map, key) { |
| for (final k in map.keys) { |
| if (key == k) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| static putIfAbsent(Map map, key, ifAbsent()) { |
| if (map.containsKey(key)) { |
| return map[key]; |
| } |
| final v = ifAbsent(); |
| map[key] = v; |
| return v; |
| } |
| |
| static clear(Map map) { |
| for (final k in map.keys.toList()) { |
| map.remove(k); |
| } |
| } |
| |
| static forEach(Map map, void f(key, value)) { |
| for (final k in map.keys) { |
| f(k, map[k]); |
| } |
| } |
| |
| static Iterable getValues(Map map) { |
| return map.keys.map((key) => map[key]); |
| } |
| |
| static int length(Map map) => map.keys.length; |
| |
| static bool isEmpty(Map map) => map.keys.isEmpty; |
| |
| static bool isNotEmpty(Map map) => map.keys.isNotEmpty; |
| |
| // A list to identify cyclic maps during toString() calls. |
| static List _toStringList = new List(); |
| |
| /** |
| * Returns a string representing the specified map. The returned string |
| * looks like this: [:'{key0: value0, key1: value1, ... keyN: valueN}':]. |
| * The value returned by its [toString] method is used to represent each |
| * key or value. |
| * |
| * If the map collection contains a reference to itself, either |
| * directly as a key or value, or indirectly through other collections |
| * or maps, the contained reference is rendered as [:'{...}':]. This |
| * prevents the infinite regress that would otherwise occur. So, for example, |
| * calling this method on a map whose sole entry maps the string key 'me' |
| * to a reference to the map would return [:'{me: {...}}':]. |
| * |
| * A typical implementation of a map's [toString] method will |
| * simply return the results of this method applied to the collection. |
| */ |
| static String mapToString(Map m) { |
| for (int i = 0; i < _toStringList.length; i++) { |
| if (identical(_toStringList[i], m)) { return '{...}'; } |
| } |
| |
| var result = new StringBuffer(); |
| try { |
| _toStringList.add(m); |
| result.write('{'); |
| bool first = true; |
| m.forEach((k, v) { |
| if(!first) { |
| result.write(', '); |
| } |
| first = false; |
| result.write(k); |
| result.write(': '); |
| result.write(v); |
| }); |
| result.write('}'); |
| } finally { |
| assert(identical(_toStringList.last, m)); |
| _toStringList.removeLast(); |
| } |
| |
| return result.toString(); |
| } |
| |
| static _id(x) => x; |
| |
| /** |
| * Fills a map with key/value pairs computed from [iterable]. |
| * |
| * This method is used by Map classes in the named constructor fromIterable. |
| */ |
| static void _fillMapWithMappedIterable(Map map, Iterable iterable, |
| key(element), value(element)) { |
| if (key == null) key = _id; |
| if (value == null) value = _id; |
| |
| for (var element in iterable) { |
| map[key(element)] = value(element); |
| } |
| } |
| |
| /** |
| * Fills a map by associating the [keys] to [values]. |
| * |
| * This method is used by Map classes in the named constructor fromIterables. |
| */ |
| static void _fillMapWithIterables(Map map, Iterable keys, |
| Iterable values) { |
| Iterator keyIterator = keys.iterator; |
| Iterator valueIterator = values.iterator; |
| |
| bool hasNextKey = keyIterator.moveNext(); |
| bool hasNextValue = valueIterator.moveNext(); |
| |
| while (hasNextKey && hasNextValue) { |
| map[keyIterator.current] = valueIterator.current; |
| hasNextKey = keyIterator.moveNext(); |
| hasNextValue = valueIterator.moveNext(); |
| } |
| |
| if (hasNextKey || hasNextValue) { |
| throw new ArgumentError("Iterables do not have same length."); |
| } |
| } |
| } |