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| 1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file |
| 2 // for details. All rights reserved. Use of this source code is governed by a |
| 3 // BSD-style license that can be found in the LICENSE file. |
| 4 |
| 5 library dart.pkg.collection.canonicalized_map; |
| 6 |
| 7 import 'dart:collection'; |
| 8 |
| 9 import 'utils.dart'; |
| 10 |
| 11 /** |
| 12 * A map whose keys are converted to canonical values of type `C`. |
| 13 * |
| 14 * This is useful for using case-insensitive String keys, for example. It's more |
| 15 * efficient than a [LinkedHashMap] with a custom equality operator because it |
| 16 * only canonicalizes each key once, rather than doing so for each comparison. |
| 17 * |
| 18 * By default, `null` is allowed as a key. It can be forbidden via the |
| 19 * `isValidKey` parameter. |
| 20 */ |
| 21 class CanonicalizedMap<C, K, V> implements Map<K, V> { |
| 22 final Function _canonicalize; |
| 23 |
| 24 final Function _isValidKeyFn; |
| 25 |
| 26 final _base = new Map<C, Pair<K, V>>(); |
| 27 |
| 28 /** |
| 29 * Creates an empty canonicalized map. |
| 30 * |
| 31 * The [canonicalize] function should return the canonical value for the given |
| 32 * key. Keys with the same canonical value are considered equivalent. |
| 33 * |
| 34 * The [isValidKey] function is called before calling [canonicalize] for |
| 35 * methods that take arbitrary objects. It can be used to filter out keys that |
| 36 * can't be canonicalized. |
| 37 */ |
| 38 CanonicalizedMap(C canonicalize(K key), {bool isValidKey(Object key)}) |
| 39 : _canonicalize = canonicalize, |
| 40 _isValidKeyFn = isValidKey; |
| 41 |
| 42 /** |
| 43 * Creates a canonicalized map that is initialized with the key/value pairs of |
| 44 * [other]. |
| 45 * |
| 46 * The [canonicalize] function should return the canonical value for the given |
| 47 * key. Keys with the same canonical value are considered equivalent. |
| 48 * |
| 49 * The [isValidKey] function is called before calling [canonicalize] for |
| 50 * methods that take arbitrary objects. It can be used to filter out keys that |
| 51 * can't be canonicalized. |
| 52 */ |
| 53 CanonicalizedMap.from(Map<K, V> other, C canonicalize(K key), |
| 54 {bool isValidKey(Object key)}) |
| 55 : _canonicalize = canonicalize, |
| 56 _isValidKeyFn = isValidKey { |
| 57 addAll(other); |
| 58 } |
| 59 |
| 60 V operator [](Object key) { |
| 61 if (!_isValidKey(key)) return null; |
| 62 var pair = _base[_canonicalize(key)]; |
| 63 return pair == null ? null : pair.last; |
| 64 } |
| 65 |
| 66 void operator []=(K key, V value) { |
| 67 _base[_canonicalize(key)] = new Pair(key, value); |
| 68 } |
| 69 |
| 70 void addAll(Map<K, V> other) { |
| 71 other.forEach((key, value) => this[key] = value); |
| 72 } |
| 73 |
| 74 void clear() { |
| 75 _base.clear(); |
| 76 } |
| 77 |
| 78 bool containsKey(Object key) { |
| 79 if (!_isValidKey(key)) return false; |
| 80 return _base.containsKey(_canonicalize(key)); |
| 81 } |
| 82 |
| 83 bool containsValue(Object value) => |
| 84 _base.values.any((pair) => pair.last == value); |
| 85 |
| 86 void forEach(void f(K key, V value)) { |
| 87 _base.forEach((key, pair) => f(pair.first, pair.last)); |
| 88 } |
| 89 |
| 90 bool get isEmpty => _base.isEmpty; |
| 91 |
| 92 bool get isNotEmpty => _base.isNotEmpty; |
| 93 |
| 94 Iterable<K> get keys => _base.values.map((pair) => pair.first); |
| 95 |
| 96 int get length => _base.length; |
| 97 |
| 98 V putIfAbsent(K key, V ifAbsent()) { |
| 99 return _base.putIfAbsent(_canonicalize(key), |
| 100 () => new Pair(key, ifAbsent())).last; |
| 101 } |
| 102 |
| 103 V remove(Object key) { |
| 104 if (!_isValidKey(key)) return null; |
| 105 var pair = _base.remove(_canonicalize(key)); |
| 106 return pair == null ? null : pair.last; |
| 107 } |
| 108 |
| 109 Iterable<V> get values => _base.values.map((pair) => pair.last); |
| 110 |
| 111 String toString() => Maps.mapToString(this); |
| 112 |
| 113 bool _isValidKey(Object key) => (key == null || key is K) && |
| 114 (_isValidKeyFn == null || _isValidKeyFn(key)); |
| 115 } |
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