| // Copyright (c) 2013, 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; |
| |
| /** |
| * A hash-table based implementation of [Map]. |
| * |
| * Keys insertion order is remembered, and keys are iterated in insertion order. |
| * Values are iterated in their corresponding key's order. |
| * |
| * The keys of a `LinkedHashMap` must have consistent [Object.operator==] |
| * and [Object.hashCode] implementations. This means that the `==` operator |
| * must define a stable equivalence relation on the keys (reflexive, |
| * anti-symmetric, transitive, and consistent over time), and that `hashCode` |
| * must be the same for objects that are considered equal by `==`. |
| * |
| * The map allows `null` as a key. |
| */ |
| abstract class LinkedHashMap<K, V> implements HashMap<K, V> { |
| external factory LinkedHashMap({ bool equals(K key1, K key2), |
| int hashCode(K key), |
| bool isValidKey(potentialKey) }); |
| |
| /** |
| * Creates an insertion-ordered identity-based map. |
| * |
| * Effectively a shorthand for: |
| * |
| * new LinkedHashMap(equals: identical, hashCode: identityHashCodeOf) |
| */ |
| external factory LinkedHashMap.identity(); |
| |
| /** |
| * Creates a [LinkedHashMap] that contains all key value pairs of [other]. |
| */ |
| factory LinkedHashMap.from(Map<K, V> other) { |
| return new LinkedHashMap<K, V>()..addAll(other); |
| } |
| |
| /** |
| * Creates a [LinkedHashMap] where the keys and values are computed from the |
| * [iterable]. |
| * |
| * For each element of the [iterable] this constructor computes a key/value |
| * pair, by applying [key] and [value] respectively. |
| * |
| * The keys of the key/value pairs do not need to be unique. The last |
| * occurrence of a key will simply overwrite any previous value. |
| * |
| * If no values are specified for [key] and [value] the default is the |
| * identity function. |
| */ |
| factory LinkedHashMap.fromIterable(Iterable iterable, |
| {K key(element), V value(element)}) { |
| LinkedHashMap<K, V> map = new LinkedHashMap<K, V>(); |
| Maps._fillMapWithMappedIterable(map, iterable, key, value); |
| return map; |
| } |
| |
| /** |
| * Creates a [LinkedHashMap] associating the given [keys] to [values]. |
| * |
| * This constructor iterates over [keys] and [values] and maps each element of |
| * [keys] to the corresponding element of [values]. |
| * |
| * If [keys] contains the same object multiple times, the last occurrence |
| * overwrites the previous value. |
| * |
| * It is an error if the two [Iterable]s don't have the same length. |
| */ |
| factory LinkedHashMap.fromIterables(Iterable<K> keys, Iterable<V> values) { |
| LinkedHashMap<K, V> map = new LinkedHashMap<K, V>(); |
| Maps._fillMapWithIterables(map, keys, values); |
| return map; |
| } |
| } |