| // 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'; |
| |
| /// 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. |
| class CanonicalizedMap<C, K, V> implements Map<K, V> { |
| final C Function(K) _canonicalize; |
| |
| final bool Function(K)? _isValidKeyFn; |
| |
| final _base = <C, MapEntry<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 Function(K key) canonicalize, |
| {bool Function(K key)? isValidKey}) |
| : _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 Function(K key) canonicalize, |
| {bool Function(K key)? isValidKey}) |
| : _canonicalize = canonicalize, |
| _isValidKeyFn = isValidKey { |
| addAll(other); |
| } |
| |
| @override |
| V? operator [](Object? key) { |
| if (!_isValidKey(key)) return null; |
| var pair = _base[_canonicalize(key as K)]; |
| return pair?.value; |
| } |
| |
| @override |
| void operator []=(K key, V value) { |
| if (!_isValidKey(key)) return; |
| _base[_canonicalize(key)] = MapEntry(key, value); |
| } |
| |
| @override |
| void addAll(Map<K, V> other) { |
| other.forEach((key, value) => this[key] = value); |
| } |
| |
| @override |
| void addEntries(Iterable<MapEntry<K, V>> entries) => _base.addEntries(entries |
| .map((e) => MapEntry(_canonicalize(e.key), MapEntry(e.key, e.value)))); |
| |
| @override |
| Map<K2, V2> cast<K2, V2>() => _base.cast<K2, V2>(); |
| |
| @override |
| void clear() { |
| _base.clear(); |
| } |
| |
| @override |
| bool containsKey(Object? key) { |
| if (!_isValidKey(key)) return false; |
| return _base.containsKey(_canonicalize(key as K)); |
| } |
| |
| @override |
| bool containsValue(Object? value) => |
| _base.values.any((pair) => pair.value == value); |
| |
| @override |
| Iterable<MapEntry<K, V>> get entries => |
| _base.entries.map((e) => MapEntry(e.value.key, e.value.value)); |
| |
| @override |
| void forEach(void Function(K, V) f) { |
| _base.forEach((key, pair) => f(pair.key, pair.value)); |
| } |
| |
| @override |
| bool get isEmpty => _base.isEmpty; |
| |
| @override |
| bool get isNotEmpty => _base.isNotEmpty; |
| |
| @override |
| Iterable<K> get keys => _base.values.map((pair) => pair.key); |
| |
| @override |
| int get length => _base.length; |
| |
| @override |
| Map<K2, V2> map<K2, V2>(MapEntry<K2, V2> Function(K, V) transform) => |
| _base.map((_, pair) => transform(pair.key, pair.value)); |
| |
| @override |
| V putIfAbsent(K key, V Function() ifAbsent) { |
| return _base |
| .putIfAbsent(_canonicalize(key), () => MapEntry(key, ifAbsent())) |
| .value; |
| } |
| |
| @override |
| V? remove(Object? key) { |
| if (!_isValidKey(key)) return null; |
| var pair = _base.remove(_canonicalize(key as K)); |
| return pair?.value; |
| } |
| |
| @override |
| void removeWhere(bool Function(K key, V value) test) => |
| _base.removeWhere((_, pair) => test(pair.key, pair.value)); |
| |
| @Deprecated('Use cast instead') |
| Map<K2, V2> retype<K2, V2>() => cast<K2, V2>(); |
| |
| @override |
| V update(K key, V Function(V) update, {V Function()? ifAbsent}) => |
| _base.update(_canonicalize(key), (pair) { |
| var value = pair.value; |
| var newValue = update(value); |
| if (identical(newValue, value)) return pair; |
| return MapEntry(key, newValue); |
| }, |
| ifAbsent: |
| ifAbsent == null ? null : () => MapEntry(key, ifAbsent())).value; |
| |
| @override |
| void updateAll(V Function(K key, V value) update) => |
| _base.updateAll((_, pair) { |
| var value = pair.value; |
| var key = pair.key; |
| var newValue = update(key, value); |
| if (identical(value, newValue)) return pair; |
| return MapEntry(key, newValue); |
| }); |
| |
| @override |
| Iterable<V> get values => _base.values.map((pair) => pair.value); |
| |
| @override |
| String toString() => MapBase.mapToString(this); |
| |
| bool _isValidKey(Object? key) => |
| (key is K) && (_isValidKeyFn == null || _isValidKeyFn!(key)); |
| } |