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Side by Side Diff: test/generated_sdk/lib/collection/hash_map.dart

Issue 1162723007: remove generated_sdk from checked in code (Closed) Base URL: git@github.com:dart-lang/dev_compiler.git@master
Patch Set: Created 5 years, 6 months ago
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1 // Copyright (c) 2013, 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 part of dart.collection;
6
7 /** Default function for equality comparison in customized HashMaps */
8 bool _defaultEquals(Object a, Object b) => a == b;
9 /** Default function for hash-code computation in customized HashMaps */
10 int _defaultHashCode(Object a) => a.hashCode;
11
12 /** Type of custom equality function */
13 typedef bool _Equality<K>(K a, K b);
14 /** Type of custom hash code function. */
15 typedef int _Hasher<K>(K object);
16
17 /**
18 * A hash-table based implementation of [Map].
19 *
20 * The keys of a `HashMap` must have consistent [Object.operator==]
21 * and [Object.hashCode] implementations. This means that the `==` operator
22 * must define a stable equivalence relation on the keys (reflexive,
23 * symmetric, transitive, and consistent over time), and that `hashCode`
24 * must be the same for objects that are considered equal by `==`.
25 *
26 * The map allows `null` as a key.
27 *
28 * Iterating the map's keys, values or entries (through [forEach])
29 * may happen in any order.
30 * The itearation order only changes when the map is modified.
31 * Values are iterated in the same order as their associated keys,
32 * so iterating the [keys] and [values] in parallel
33 * will give matching key and value pairs.
34 */
35 abstract class HashMap<K, V> implements Map<K, V> {
36 /**
37 * Creates an unordered hash-table based [Map].
38 *
39 * The created map is not ordered in any way. When iterating the keys or
40 * values, the iteration order is unspecified except that it will stay the
41 * same as long as the map isn't changed.
42 *
43 * If [equals] is provided, it is used to compare the keys in the table with
44 * new keys. If [equals] is omitted, the key's own [Object.operator==] is used
45 * instead.
46 *
47 * Similar, if [hashCode] is provided, it is used to produce a hash value
48 * for keys in order to place them in the hash table. If it is omitted, the
49 * key's own [Object.hashCode] is used.
50 *
51 * If using methods like [operator[]], [remove] and [containsKey] together
52 * with a custom equality and hashcode, an extra `isValidKey` function
53 * can be supplied. This function is called before calling [equals] or
54 * [hashCode] with an argument that may not be a [K] instance, and if the
55 * call returns false, the key is assumed to not be in the set.
56 * The [isValidKey] function defaults to just testing if the object is a
57 * [K] instance.
58 *
59 * The used `equals` and `hashCode` method should always be consistent,
60 * so that if `equals(a, b)` then `hashCode(a) == hashCode(b)`. The hash
61 * of an object, or what it compares equal to, should not change while the
62 * object is in the table. If it does change, the result is unpredictable.
63 *
64 * If you supply one of [equals] and [hashCode],
65 * you should generally also to supply the other.
66 * An example would be using [identical] and [identityHashCode],
67 * which is equivalent to using the shorthand [HashMap.identity]).
68 */
69 factory HashMap({ bool equals(K key1, K key2),
70 int hashCode(K key),
71 bool isValidKey(Object potentialKey) }) {
72 if (isValidKey == null) {
73 if (hashCode == null) {
74 if (equals == null) {
75 return new _HashMap<K, V>();
76 }
77 hashCode = _defaultHashCode;
78 } else {
79 if (identical(identityHashCode, hashCode) &&
80 identical(identical, equals)) {
81 return new _IdentityHashMap<K, V>();
82 }
83 if (equals == null) {
84 equals = _defaultEquals;
85 }
86 }
87 } else {
88 if (hashCode == null) {
89 hashCode = _defaultHashCode;
90 }
91 if (equals == null) {
92 equals = _defaultEquals;
93 }
94 }
95 return new _CustomHashMap<K, V>(equals, hashCode, isValidKey);
96 }
97
98 /**
99 * Creates an unordered identity-based map.
100 *
101 * Effectively a shorthand for:
102 *
103 * new HashMap(equals: identical, hashCode: identityHashCodeOf)
104 */
105 factory HashMap.identity() = _IdentityHashMap<K, V>;
106
107 /**
108 * Creates a [HashMap] that contains all key/value pairs of [other].
109 */
110 factory HashMap.from(Map other) {
111 HashMap<K, V> result = new HashMap<K, V>();
112 other.forEach((k, v) { result[k] = v; });
113 return result;
114 }
115
116 /**
117 * Creates a [HashMap] where the keys and values are computed from the
118 * [iterable].
119 *
120 * For each element of the [iterable] this constructor computes a key/value
121 * pair, by applying [key] and [value] respectively.
122 *
123 * The keys of the key/value pairs do not need to be unique. The last
124 * occurrence of a key will simply overwrite any previous value.
125 *
126 * If no values are specified for [key] and [value] the default is the
127 * identity function.
128 */
129 factory HashMap.fromIterable(Iterable iterable,
130 {K key(element), V value(element)}) {
131 HashMap<K, V> map = new HashMap<K, V>();
132 Maps._fillMapWithMappedIterable(map, iterable, key, value);
133 return map;
134 }
135
136 /**
137 * Creates a [HashMap] associating the given [keys] to [values].
138 *
139 * This constructor iterates over [keys] and [values] and maps each element of
140 * [keys] to the corresponding element of [values].
141 *
142 * If [keys] contains the same object multiple times, the last occurrence
143 * overwrites the previous value.
144 *
145 * It is an error if the two [Iterable]s don't have the same length.
146 */
147 factory HashMap.fromIterables(Iterable<K> keys, Iterable<V> values) {
148 HashMap<K, V> map = new HashMap<K, V>();
149 Maps._fillMapWithIterables(map, keys, values);
150 return map;
151 }
152 }
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