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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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