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1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file | 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 | 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. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 import 'dart:collection'; | 5 import 'dart:collection'; |
6 | 6 |
7 /** | 7 /// A class that efficiently implements both [Queue] and [List]. |
8 * A class that efficiently implements both [Queue] and [List]. | |
9 */ | |
10 // TODO(nweiz): Currently this code is copied almost verbatim from | 8 // TODO(nweiz): Currently this code is copied almost verbatim from |
11 // dart:collection. The only changes are to implement List and to remove methods | 9 // dart:collection. The only changes are to implement List and to remove methods |
12 // that are redundant with ListMixin. Remove or simplify it when issue 21330 is | 10 // that are redundant with ListMixin. Remove or simplify it when issue 21330 is |
13 // fixed. | 11 // fixed. |
14 class QueueList<E> extends Object with ListMixin<E> implements Queue<E> { | 12 class QueueList<E> extends Object with ListMixin<E> implements Queue<E> { |
15 static const int _INITIAL_CAPACITY = 8; | 13 static const int _INITIAL_CAPACITY = 8; |
16 List<E> _table; | 14 List<E> _table; |
17 int _head; | 15 int _head; |
18 int _tail; | 16 int _tail; |
19 | 17 |
20 /** | 18 /// Create an empty queue. |
21 * Create an empty queue. | 19 /// |
22 * | 20 /// If [initialCapacity] is given, prepare the queue for at least that many |
23 * If [initialCapacity] is given, prepare the queue for at least that many | 21 /// elements. |
24 * elements. | 22 QueueList([int initialCapacity]) |
25 */ | 23 : _head = 0, |
26 QueueList([int initialCapacity]) : _head = 0, _tail = 0 { | 24 _tail = 0 { |
27 if (initialCapacity == null || initialCapacity < _INITIAL_CAPACITY) { | 25 if (initialCapacity == null || initialCapacity < _INITIAL_CAPACITY) { |
28 initialCapacity = _INITIAL_CAPACITY; | 26 initialCapacity = _INITIAL_CAPACITY; |
29 } else if (!_isPowerOf2(initialCapacity)) { | 27 } else if (!_isPowerOf2(initialCapacity)) { |
30 initialCapacity = _nextPowerOf2(initialCapacity); | 28 initialCapacity = _nextPowerOf2(initialCapacity); |
31 } | 29 } |
32 assert(_isPowerOf2(initialCapacity)); | 30 assert(_isPowerOf2(initialCapacity)); |
33 _table = new List<E>(initialCapacity); | 31 _table = new List<E>(initialCapacity); |
34 } | 32 } |
35 | 33 |
36 /** | 34 /// Create a queue initially containing the elements of [source]. |
37 * Create a queue initially containing the elements of [source]. | |
38 */ | |
39 factory QueueList.from(Iterable<E> source) { | 35 factory QueueList.from(Iterable<E> source) { |
40 if (source is List) { | 36 if (source is List) { |
41 int length = source.length; | 37 int length = source.length; |
42 QueueList<E> queue = new QueueList(length + 1); | 38 QueueList<E> queue = new QueueList(length + 1); |
43 assert(queue._table.length > length); | 39 assert(queue._table.length > length); |
44 List sourceList = source; | 40 var sourceList = source; |
45 queue._table.setRange(0, length, sourceList, 0); | 41 queue._table.setRange(0, length, sourceList, 0); |
46 queue._tail = length; | 42 queue._tail = length; |
47 return queue; | 43 return queue; |
48 } else { | 44 } else { |
49 return new QueueList<E>()..addAll(source); | 45 return new QueueList<E>()..addAll(source); |
50 } | 46 } |
51 } | 47 } |
52 | 48 |
53 // Collection interface. | 49 // Collection interface. |
54 | 50 |
55 void add(E element) { | 51 void add(E element) { |
56 _add(element); | 52 _add(element); |
57 } | 53 } |
58 | 54 |
59 void addAll(Iterable<E> elements) { | 55 void addAll(Iterable<E> elements) { |
60 if (elements is List) { | 56 if (elements is List) { |
61 List list = elements; | 57 var list = elements; |
62 int addCount = list.length; | 58 int addCount = list.length; |
63 int length = this.length; | 59 int length = this.length; |
64 if (length + addCount >= _table.length) { | 60 if (length + addCount >= _table.length) { |
65 _preGrow(length + addCount); | 61 _preGrow(length + addCount); |
66 // After preGrow, all elements are at the start of the list. | 62 // After preGrow, all elements are at the start of the list. |
67 _table.setRange(length, length + addCount, list, 0); | 63 _table.setRange(length, length + addCount, list, 0); |
68 _tail += addCount; | 64 _tail += addCount; |
69 } else { | 65 } else { |
70 // Adding addCount elements won't reach _head. | 66 // Adding addCount elements won't reach _head. |
71 int endSpace = _table.length - _tail; | 67 int endSpace = _table.length - _tail; |
72 if (addCount < endSpace) { | 68 if (addCount < endSpace) { |
73 _table.setRange(_tail, _tail + addCount, list, 0); | 69 _table.setRange(_tail, _tail + addCount, list, 0); |
74 _tail += addCount; | 70 _tail += addCount; |
75 } else { | 71 } else { |
76 int preSpace = addCount - endSpace; | 72 int preSpace = addCount - endSpace; |
77 _table.setRange(_tail, _tail + endSpace, list, 0); | 73 _table.setRange(_tail, _tail + endSpace, list, 0); |
78 _table.setRange(0, preSpace, list, endSpace); | 74 _table.setRange(0, preSpace, list, endSpace); |
79 _tail = preSpace; | 75 _tail = preSpace; |
80 } | 76 } |
81 } | 77 } |
82 } else { | 78 } else { |
83 for (E element in elements) _add(element); | 79 for (E element in elements) _add(element); |
84 } | 80 } |
85 } | 81 } |
86 | 82 |
87 String toString() => IterableBase.iterableToFullString(this, "{", "}"); | 83 String toString() => IterableBase.iterableToFullString(this, "{", "}"); |
88 | 84 |
89 // Queue interface. | 85 // Queue interface. |
90 | 86 |
91 void addLast(E element) { _add(element); } | 87 void addLast(E element) { |
| 88 _add(element); |
| 89 } |
92 | 90 |
93 void addFirst(E element) { | 91 void addFirst(E element) { |
94 _head = (_head - 1) & (_table.length - 1); | 92 _head = (_head - 1) & (_table.length - 1); |
95 _table[_head] = element; | 93 _table[_head] = element; |
96 if (_head == _tail) _grow(); | 94 if (_head == _tail) _grow(); |
97 } | 95 } |
98 | 96 |
99 E removeFirst() { | 97 E removeFirst() { |
100 if (_head == _tail) throw new StateError("No element"); | 98 if (_head == _tail) throw new StateError("No element"); |
101 E result = _table[_head]; | 99 E result = _table[_head]; |
(...skipping 22 matching lines...) Expand all Loading... |
124 if (_table.length <= value) { | 122 if (_table.length <= value) { |
125 _preGrow(value); | 123 _preGrow(value); |
126 } | 124 } |
127 _tail = (_tail + delta) & (_table.length - 1); | 125 _tail = (_tail + delta) & (_table.length - 1); |
128 return; | 126 return; |
129 } | 127 } |
130 | 128 |
131 int newTail = _tail + delta; // [delta] is negative. | 129 int newTail = _tail + delta; // [delta] is negative. |
132 if (newTail >= 0) { | 130 if (newTail >= 0) { |
133 _table.fillRange(newTail, _tail, null); | 131 _table.fillRange(newTail, _tail, null); |
134 } else { | 132 } else { |
135 newTail += _table.length; | 133 newTail += _table.length; |
136 _table.fillRange(0, _tail, null); | 134 _table.fillRange(0, _tail, null); |
137 _table.fillRange(newTail, _table.length, null); | 135 _table.fillRange(newTail, _table.length, null); |
138 } | 136 } |
139 _tail = newTail; | 137 _tail = newTail; |
140 } | 138 } |
141 | 139 |
142 E operator [](int index) { | 140 E operator [](int index) { |
143 if (index < 0 || index >= length) { | 141 if (index < 0 || index >= length) { |
144 throw new RangeError("Index $index must be in the range [0..$length)."); | 142 throw new RangeError("Index $index must be in the range [0..$length)."); |
145 } | 143 } |
146 | 144 |
147 return _table[(_head + index) & (_table.length - 1)]; | 145 return _table[(_head + index) & (_table.length - 1)]; |
148 } | 146 } |
149 | 147 |
150 void operator[]=(int index, E value) { | 148 void operator []=(int index, E value) { |
151 if (index < 0 || index >= length) { | 149 if (index < 0 || index >= length) { |
152 throw new RangeError("Index $index must be in the range [0..$length)."); | 150 throw new RangeError("Index $index must be in the range [0..$length)."); |
153 } | 151 } |
154 | 152 |
155 _table[(_head + index) & (_table.length - 1)] = value; | 153 _table[(_head + index) & (_table.length - 1)] = value; |
156 } | 154 } |
157 | 155 |
158 // Internal helper functions. | 156 // Internal helper functions. |
159 | 157 |
160 /** | 158 /// Whether [number] is a power of two. |
161 * Whether [number] is a power of two. | 159 /// |
162 * | 160 /// Only works for positive numbers. |
163 * Only works for positive numbers. | |
164 */ | |
165 static bool _isPowerOf2(int number) => (number & (number - 1)) == 0; | 161 static bool _isPowerOf2(int number) => (number & (number - 1)) == 0; |
166 | 162 |
167 /** | 163 /// Rounds [number] up to the nearest power of 2. |
168 * Rounds [number] up to the nearest power of 2. | 164 /// |
169 * | 165 /// If [number] is a power of 2 already, it is returned. |
170 * If [number] is a power of 2 already, it is returned. | 166 /// |
171 * | 167 /// Only works for positive numbers. |
172 * Only works for positive numbers. | |
173 */ | |
174 static int _nextPowerOf2(int number) { | 168 static int _nextPowerOf2(int number) { |
175 assert(number > 0); | 169 assert(number > 0); |
176 number = (number << 1) - 1; | 170 number = (number << 1) - 1; |
177 for(;;) { | 171 for (;;) { |
178 int nextNumber = number & (number - 1); | 172 int nextNumber = number & (number - 1); |
179 if (nextNumber == 0) return number; | 173 if (nextNumber == 0) return number; |
180 number = nextNumber; | 174 number = nextNumber; |
181 } | 175 } |
182 } | 176 } |
183 | 177 |
184 /** Adds element at end of queue. Used by both [add] and [addAll]. */ | 178 /// Adds element at end of queue. Used by both [add] and [addAll]. |
185 void _add(E element) { | 179 void _add(E element) { |
186 _table[_tail] = element; | 180 _table[_tail] = element; |
187 _tail = (_tail + 1) & (_table.length - 1); | 181 _tail = (_tail + 1) & (_table.length - 1); |
188 if (_head == _tail) _grow(); | 182 if (_head == _tail) _grow(); |
189 } | 183 } |
190 | 184 |
191 /** | 185 /// Grow the table when full. |
192 * Grow the table when full. | |
193 */ | |
194 void _grow() { | 186 void _grow() { |
195 List<E> newTable = new List<E>(_table.length * 2); | 187 List<E> newTable = new List<E>(_table.length * 2); |
196 int split = _table.length - _head; | 188 int split = _table.length - _head; |
197 newTable.setRange(0, split, _table, _head); | 189 newTable.setRange(0, split, _table, _head); |
198 newTable.setRange(split, split + _head, _table, 0); | 190 newTable.setRange(split, split + _head, _table, 0); |
199 _head = 0; | 191 _head = 0; |
200 _tail = _table.length; | 192 _tail = _table.length; |
201 _table = newTable; | 193 _table = newTable; |
202 } | 194 } |
203 | 195 |
204 int _writeToList(List<E> target) { | 196 int _writeToList(List<E> target) { |
205 assert(target.length >= length); | 197 assert(target.length >= length); |
206 if (_head <= _tail) { | 198 if (_head <= _tail) { |
207 int length = _tail - _head; | 199 int length = _tail - _head; |
208 target.setRange(0, length, _table, _head); | 200 target.setRange(0, length, _table, _head); |
209 return length; | 201 return length; |
210 } else { | 202 } else { |
211 int firstPartSize = _table.length - _head; | 203 int firstPartSize = _table.length - _head; |
212 target.setRange(0, firstPartSize, _table, _head); | 204 target.setRange(0, firstPartSize, _table, _head); |
213 target.setRange(firstPartSize, firstPartSize + _tail, _table, 0); | 205 target.setRange(firstPartSize, firstPartSize + _tail, _table, 0); |
214 return _tail + firstPartSize; | 206 return _tail + firstPartSize; |
215 } | 207 } |
216 } | 208 } |
217 | 209 |
218 /** Grows the table even if it is not full. */ | 210 /// Grows the table even if it is not full. |
219 void _preGrow(int newElementCount) { | 211 void _preGrow(int newElementCount) { |
220 assert(newElementCount >= length); | 212 assert(newElementCount >= length); |
221 | 213 |
222 // Add 1.5x extra room to ensure that there's room for more elements after | 214 // Add 1.5x extra room to ensure that there's room for more elements after |
223 // expansion. | 215 // expansion. |
224 newElementCount += newElementCount >> 1; | 216 newElementCount += newElementCount >> 1; |
225 int newCapacity = _nextPowerOf2(newElementCount); | 217 int newCapacity = _nextPowerOf2(newElementCount); |
226 List<E> newTable = new List<E>(newCapacity); | 218 List<E> newTable = new List<E>(newCapacity); |
227 _tail = _writeToList(newTable); | 219 _tail = _writeToList(newTable); |
228 _table = newTable; | 220 _table = newTable; |
229 _head = 0; | 221 _head = 0; |
230 } | 222 } |
231 } | 223 } |
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