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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 '../wrappers.dart'; | |
8 | |
9 /** | |
10 * A map whose keys are converted to canonical values. | |
11 * | |
12 * This is useful for using case-insensitive String keys, for example. It's more | |
13 * efficient than a [LinkedHashMap] with a custom equality operator because it | |
14 * only canonicalizes each once, rather than doing so for each comparison. | |
15 */ | |
16 class CanonicalizedMap<K, V> extends DelegatingMap<K, V> { | |
Lasse Reichstein Nielsen
2014/06/27 06:57:47
Could we allow the canonicalization of a key to no
nweiz
2014/06/30 20:37:46
Done.
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17 final Function _canonicalize; | |
18 | |
19 /** | |
20 * A map from the canonicalized keys to their original values. | |
21 */ | |
22 final _keys = new Map<K, V>(); | |
Lasse Reichstein Nielsen
2014/06/27 06:57:47
Should be <K,K>.
Have you considered using a
nweiz
2014/06/30 20:37:46
Done, using the Pair class that's used elsewhere i
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23 | |
24 /** | |
25 * Creates an empty canonicalized map. | |
26 * | |
27 * The [canonicalize] function should return the canonical value for the given | |
28 * key. Keys with the same canonical value are considered identical, and the | |
Lasse Reichstein Nielsen
2014/06/27 06:57:47
identical -> equivalent
Ditto below.
nweiz
2014/06/30 20:37:46
Done.
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29 * canonical values of the keys are stored in the map. | |
Lasse Reichstein Nielsen
2014/06/27 06:57:47
"stored in the map" is vague but sounds significan
nweiz
2014/06/30 20:37:46
I just removed this. It was a holdover from before
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30 */ | |
31 CanonicalizedMap(K canonicalize(K key)) | |
Lasse Reichstein Nielsen
2014/06/27 06:57:47
I'd also like to have an "bool isValidKey(Object o
Lasse Reichstein Nielsen
2014/06/27 06:57:47
Please see if you can also make the map a paramete
nweiz
2014/06/30 20:37:46
I don't completely understand the purpose of this
nweiz
2014/06/30 20:37:46
I don't think it's worth complicating the API to s
Lasse Reichstein Nielsen
2014/07/01 09:18:14
ACK, if we make the type of canonical object C ins
Lasse Reichstein Nielsen
2014/07/01 09:18:14
I assume that if isValidKey(o) return false, then
nweiz
2014/07/01 21:21:44
Done.
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32 : _canonicalize = canonicalize, | |
33 super({}); | |
34 | |
35 /** | |
36 * Creates a canonicalized map that contains all key/value pairs of [other]. | |
Lasse Reichstein Nielsen
2014/06/27 06:57:47
Because of the canonicalization, it might contain
nweiz
2014/06/30 20:37:46
Good point. Done.
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37 * | |
38 * The [canonicalize] function should return the canonical value for the given | |
39 * key. Keys with the same canonical value are considered identical, and the | |
40 * canonical values of the keys are stored in the map. | |
41 */ | |
42 CanonicalizedMap.from(Map<K, V> other, K canonicalize(K key)) | |
43 : _canonicalize = canonicalize, | |
44 super({}) { | |
45 addAll(other); | |
46 } | |
47 | |
48 V operator [](Object key) { | |
49 if (key != null && key is! K) return null; | |
50 return super[_canonicalize(key)]; | |
51 } | |
52 | |
53 void operator []=(K key, V value) { | |
54 var canonical = _canonicalize(key); | |
55 _keys[canonical] = key; | |
56 super[canonical] = value; | |
57 } | |
58 | |
59 void addAll(Map<K, V> other) { | |
60 other.forEach((key, value) => this[key] = value); | |
61 } | |
62 | |
63 bool containsKey(Object key) { | |
64 if (key != null && key is! K) return null; | |
65 return super.containsKey(_canonicalize(key)); | |
66 } | |
67 | |
68 void forEach(void f(K key, V value)) { | |
69 super.forEach((key, value) => f(_keys[key], value)); | |
70 } | |
71 | |
72 Iterable<K> get keys => _keys.values; | |
73 | |
74 V putIfAbsent(K key, V ifAbsent()) { | |
75 var canonical = _canonicalize(key); | |
76 return super.putIfAbsent(canonical, () { | |
77 _keys[canonical] = key; | |
78 return ifAbsent(); | |
79 }); | |
80 } | |
81 | |
82 V remove(Object key) { | |
83 if (key != null && key is! K) return null; | |
84 var canonical = _canonicalize(key); | |
85 _keys.remove(canonical); | |
86 return super.remove(canonical); | |
87 } | |
88 } | |
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