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96 lines
3.2 KiB
C++
96 lines
3.2 KiB
C++
/*
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* Copyright (C) 2010 Apple Inc. All Rights Reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#ifndef SKY_ENGINE_WTF_NONCOPYINGSORT_H_
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#define SKY_ENGINE_WTF_NONCOPYINGSORT_H_
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namespace WTF {
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using std::swap;
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template <typename RandomAccessIterator, typename Predicate>
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inline void siftDown(RandomAccessIterator array,
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ptrdiff_t start,
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ptrdiff_t end,
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Predicate compareLess) {
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ptrdiff_t root = start;
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while (root * 2 + 1 <= end) {
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ptrdiff_t child = root * 2 + 1;
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if (child < end && compareLess(array[child], array[child + 1]))
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child++;
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if (compareLess(array[root], array[child])) {
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swap(array[root], array[child]);
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root = child;
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} else
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return;
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}
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}
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template <typename RandomAccessIterator, typename Predicate>
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inline void heapify(RandomAccessIterator array,
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ptrdiff_t count,
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Predicate compareLess) {
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ptrdiff_t start = (count - 2) / 2;
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while (start >= 0) {
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siftDown(array, start, count - 1, compareLess);
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start--;
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}
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}
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template <typename RandomAccessIterator, typename Predicate>
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void heapSort(RandomAccessIterator start,
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RandomAccessIterator end,
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Predicate compareLess) {
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ptrdiff_t count = end - start;
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heapify(start, count, compareLess);
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ptrdiff_t endIndex = count - 1;
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while (endIndex > 0) {
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swap(start[endIndex], start[0]);
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siftDown(start, 0, endIndex - 1, compareLess);
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endIndex--;
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}
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}
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template <typename RandomAccessIterator, typename Predicate>
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inline void nonCopyingSort(RandomAccessIterator start,
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RandomAccessIterator end,
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Predicate compareLess) {
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// heapsort happens to use only swaps, not copies, but the essential thing
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// about this function is the fact that it does not copy, not the specific
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// algorithm
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heapSort(start, end, compareLess);
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}
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} // namespace WTF
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using WTF::nonCopyingSort;
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#endif // SKY_ENGINE_WTF_NONCOPYINGSORT_H_
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