| // 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. |
| |
| import 'dart:collection'; |
| |
| import 'utils.dart'; |
| |
| typedef C _Canonicalize<C, K>(K key); |
| |
| typedef bool _IsValidKey(Object key); |
| |
| /// A map whose keys are converted to canonical values of type `C`. |
| /// |
| /// This is useful for using case-insensitive String keys, for example. It's |
| /// more efficient than a [LinkedHashMap] with a custom equality operator |
| /// because it only canonicalizes each key once, rather than doing so for each |
| /// comparison. |
| /// |
| /// By default, `null` is allowed as a key. It can be forbidden via the |
| /// `isValidKey` parameter. |
| class CanonicalizedMap<C, K, V> implements Map<K, V> { |
| final _Canonicalize<C, K> _canonicalize; |
| |
| final _IsValidKey _isValidKeyFn; |
| |
| final _base = new Map<C, Pair<K, V>>(); |
| |
| /// Creates an empty canonicalized map. |
| /// |
| /// The [canonicalize] function should return the canonical value for the |
| /// given key. Keys with the same canonical value are considered equivalent. |
| /// |
| /// The [isValidKey] function is called before calling [canonicalize] for |
| /// methods that take arbitrary objects. It can be used to filter out keys |
| /// that can't be canonicalized. |
| CanonicalizedMap(C canonicalize(K key), {bool isValidKey(Object key)}) |
| : _canonicalize = canonicalize, |
| _isValidKeyFn = isValidKey; |
| |
| /// Creates a canonicalized map that is initialized with the key/value pairs |
| /// of [other]. |
| /// |
| /// The [canonicalize] function should return the canonical value for the |
| /// given key. Keys with the same canonical value are considered equivalent. |
| /// |
| /// The [isValidKey] function is called before calling [canonicalize] for |
| /// methods that take arbitrary objects. It can be used to filter out keys |
| /// that can't be canonicalized. |
| CanonicalizedMap.from(Map<K, V> other, C canonicalize(K key), |
| {bool isValidKey(Object key)}) |
| : _canonicalize = canonicalize, |
| _isValidKeyFn = isValidKey { |
| addAll(other); |
| } |
| |
| V operator [](Object key) { |
| if (!_isValidKey(key)) return null; |
| var pair = _base[_canonicalize(key as K)]; |
| return pair == null ? null : pair.last; |
| } |
| |
| void operator []=(K key, V value) { |
| if (!_isValidKey(key)) return; |
| _base[_canonicalize(key)] = new Pair(key, value); |
| } |
| |
| void addAll(Map<K, V> other) { |
| other.forEach((key, value) => this[key] = value); |
| } |
| |
| void clear() { |
| _base.clear(); |
| } |
| |
| bool containsKey(Object key) { |
| if (!_isValidKey(key)) return false; |
| return _base.containsKey(_canonicalize(key as K)); |
| } |
| |
| bool containsValue(Object value) => |
| _base.values.any((pair) => pair.last == value); |
| |
| void forEach(void f(K key, V value)) { |
| _base.forEach((key, pair) => f(pair.first, pair.last)); |
| } |
| |
| bool get isEmpty => _base.isEmpty; |
| |
| bool get isNotEmpty => _base.isNotEmpty; |
| |
| Iterable<K> get keys => _base.values.map((pair) => pair.first); |
| |
| int get length => _base.length; |
| |
| V putIfAbsent(K key, V ifAbsent()) { |
| return _base.putIfAbsent(_canonicalize(key), |
| () => new Pair(key, ifAbsent())).last; |
| } |
| |
| V remove(Object key) { |
| if (!_isValidKey(key)) return null; |
| var pair = _base.remove(_canonicalize(key as K)); |
| return pair == null ? null : pair.last; |
| } |
| |
| Iterable<V> get values => _base.values.map((pair) => pair.last); |
| |
| String toString() => Maps.mapToString(this); |
| |
| bool _isValidKey(Object key) => (key == null || key is K) && |
| (_isValidKeyFn == null || _isValidKeyFn(key)); |
| } |