Index: collection/lib/src/queue_list.dart |
diff --git a/collection/lib/src/queue_list.dart b/collection/lib/src/queue_list.dart |
deleted file mode 100644 |
index 0ef888f9c1fb9f666f8463e5d4c0b2925b2e0803..0000000000000000000000000000000000000000 |
--- a/collection/lib/src/queue_list.dart |
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-// Copyright (c) 2014, 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. |
- |
-import 'dart:collection'; |
- |
-/** |
- * A class that efficiently implements both [Queue] and [List]. |
- */ |
-// TODO(nweiz): Currently this code is copied almost verbatim from |
-// dart:collection. The only changes are to implement List and to remove methods |
-// that are redundant with ListMixin. Remove or simplify it when issue 21330 is |
-// fixed. |
-class QueueList<E> extends Object with ListMixin<E> implements Queue<E> { |
- static const int _INITIAL_CAPACITY = 8; |
- List<E> _table; |
- int _head; |
- int _tail; |
- |
- /** |
- * Create an empty queue. |
- * |
- * If [initialCapacity] is given, prepare the queue for at least that many |
- * elements. |
- */ |
- QueueList([int initialCapacity]) : _head = 0, _tail = 0 { |
- if (initialCapacity == null || initialCapacity < _INITIAL_CAPACITY) { |
- initialCapacity = _INITIAL_CAPACITY; |
- } else if (!_isPowerOf2(initialCapacity)) { |
- initialCapacity = _nextPowerOf2(initialCapacity); |
- } |
- assert(_isPowerOf2(initialCapacity)); |
- _table = new List<E>(initialCapacity); |
- } |
- |
- /** |
- * Create a queue initially containing the elements of [source]. |
- */ |
- factory QueueList.from(Iterable<E> source) { |
- if (source is List) { |
- int length = source.length; |
- QueueList<E> queue = new QueueList(length + 1); |
- assert(queue._table.length > length); |
- List sourceList = source; |
- queue._table.setRange(0, length, sourceList, 0); |
- queue._tail = length; |
- return queue; |
- } else { |
- return new QueueList<E>()..addAll(source); |
- } |
- } |
- |
- // Collection interface. |
- |
- void add(E element) { |
- _add(element); |
- } |
- |
- void addAll(Iterable<E> elements) { |
- if (elements is List) { |
- List list = elements; |
- int addCount = list.length; |
- int length = this.length; |
- if (length + addCount >= _table.length) { |
- _preGrow(length + addCount); |
- // After preGrow, all elements are at the start of the list. |
- _table.setRange(length, length + addCount, list, 0); |
- _tail += addCount; |
- } else { |
- // Adding addCount elements won't reach _head. |
- int endSpace = _table.length - _tail; |
- if (addCount < endSpace) { |
- _table.setRange(_tail, _tail + addCount, list, 0); |
- _tail += addCount; |
- } else { |
- int preSpace = addCount - endSpace; |
- _table.setRange(_tail, _tail + endSpace, list, 0); |
- _table.setRange(0, preSpace, list, endSpace); |
- _tail = preSpace; |
- } |
- } |
- } else { |
- for (E element in elements) _add(element); |
- } |
- } |
- |
- String toString() => IterableBase.iterableToFullString(this, "{", "}"); |
- |
- // Queue interface. |
- |
- void addLast(E element) { _add(element); } |
- |
- void addFirst(E element) { |
- _head = (_head - 1) & (_table.length - 1); |
- _table[_head] = element; |
- if (_head == _tail) _grow(); |
- } |
- |
- E removeFirst() { |
- if (_head == _tail) throw new StateError("No element"); |
- E result = _table[_head]; |
- _table[_head] = null; |
- _head = (_head + 1) & (_table.length - 1); |
- return result; |
- } |
- |
- E removeLast() { |
- if (_head == _tail) throw new StateError("No element"); |
- _tail = (_tail - 1) & (_table.length - 1); |
- E result = _table[_tail]; |
- _table[_tail] = null; |
- return result; |
- } |
- |
- // List interface. |
- |
- int get length => (_tail - _head) & (_table.length - 1); |
- |
- void set length(int value) { |
- if (value < 0) throw new RangeError("Length $value may not be negative."); |
- |
- int delta = value - length; |
- if (delta >= 0) { |
- if (_table.length <= value) { |
- _preGrow(value); |
- } |
- _tail = (_tail + delta) & (_table.length - 1); |
- return; |
- } |
- |
- int newTail = _tail + delta; // [delta] is negative. |
- if (newTail >= 0) { |
- _table.fillRange(newTail, _tail, null); |
- } else { |
- newTail += _table.length; |
- _table.fillRange(0, _tail, null); |
- _table.fillRange(newTail, _table.length, null); |
- } |
- _tail = newTail; |
- } |
- |
- E operator [](int index) { |
- if (index < 0 || index >= length) { |
- throw new RangeError("Index $index must be in the range [0..$length)."); |
- } |
- |
- return _table[(_head + index) & (_table.length - 1)]; |
- } |
- |
- void operator[]=(int index, E value) { |
- if (index < 0 || index >= length) { |
- throw new RangeError("Index $index must be in the range [0..$length)."); |
- } |
- |
- _table[(_head + index) & (_table.length - 1)] = value; |
- } |
- |
- // Internal helper functions. |
- |
- /** |
- * Whether [number] is a power of two. |
- * |
- * Only works for positive numbers. |
- */ |
- static bool _isPowerOf2(int number) => (number & (number - 1)) == 0; |
- |
- /** |
- * Rounds [number] up to the nearest power of 2. |
- * |
- * If [number] is a power of 2 already, it is returned. |
- * |
- * Only works for positive numbers. |
- */ |
- static int _nextPowerOf2(int number) { |
- assert(number > 0); |
- number = (number << 1) - 1; |
- for(;;) { |
- int nextNumber = number & (number - 1); |
- if (nextNumber == 0) return number; |
- number = nextNumber; |
- } |
- } |
- |
- /** Adds element at end of queue. Used by both [add] and [addAll]. */ |
- void _add(E element) { |
- _table[_tail] = element; |
- _tail = (_tail + 1) & (_table.length - 1); |
- if (_head == _tail) _grow(); |
- } |
- |
- /** |
- * Grow the table when full. |
- */ |
- void _grow() { |
- List<E> newTable = new List<E>(_table.length * 2); |
- int split = _table.length - _head; |
- newTable.setRange(0, split, _table, _head); |
- newTable.setRange(split, split + _head, _table, 0); |
- _head = 0; |
- _tail = _table.length; |
- _table = newTable; |
- } |
- |
- int _writeToList(List<E> target) { |
- assert(target.length >= length); |
- if (_head <= _tail) { |
- int length = _tail - _head; |
- target.setRange(0, length, _table, _head); |
- return length; |
- } else { |
- int firstPartSize = _table.length - _head; |
- target.setRange(0, firstPartSize, _table, _head); |
- target.setRange(firstPartSize, firstPartSize + _tail, _table, 0); |
- return _tail + firstPartSize; |
- } |
- } |
- |
- /** Grows the table even if it is not full. */ |
- void _preGrow(int newElementCount) { |
- assert(newElementCount >= length); |
- |
- // Add 1.5x extra room to ensure that there's room for more elements after |
- // expansion. |
- newElementCount += newElementCount >> 1; |
- int newCapacity = _nextPowerOf2(newElementCount); |
- List<E> newTable = new List<E>(newCapacity); |
- _tail = _writeToList(newTable); |
- _table = newTable; |
- _head = 0; |
- } |
-} |