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| 1 /* | |
| 2 * Copyright (C) 2011 Apple Inc. All rights reserved. | |
| 3 * | |
| 4 * Redistribution and use in source and binary forms, with or without | |
| 5 * modification, are permitted provided that the following conditions | |
| 6 * are met: | |
| 7 * 1. Redistributions of source code must retain the above copyright | |
| 8 * notice, this list of conditions and the following disclaimer. | |
| 9 * 2. Redistributions in binary form must reproduce the above copyright | |
| 10 * notice, this list of conditions and the following disclaimer in the | |
| 11 * documentation and/or other materials provided with the distribution. | |
| 12 * | |
| 13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' | |
| 14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, | |
| 15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
| 16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS | |
| 17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
| 18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
| 19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
| 20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
| 21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
| 22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF | |
| 23 * THE POSSIBILITY OF SUCH DAMAGE. | |
| 24 */ | |
| 25 | |
| 26 #ifndef BlockStack_h | |
| 27 #define BlockStack_h | |
| 28 | |
| 29 #include <wtf/Assertions.h> | |
| 30 #include <wtf/FastMalloc.h> | |
| 31 #include <wtf/Vector.h> | |
| 32 | |
| 33 namespace WTF { | |
| 34 | |
| 35 template <typename T> class BlockStack { | |
| 36 public: | |
| 37 static const size_t blockSize = 4096; | |
| 38 static const size_t blockLength = blockSize / sizeof(T); | |
| 39 | |
| 40 BlockStack(); | |
| 41 ~BlockStack(); | |
| 42 | |
| 43 T* grow(); | |
| 44 void shrink(T*); | |
| 45 | |
| 46 const Vector<T*>& blocks(); | |
| 47 | |
| 48 private: | |
| 49 Vector<T*> m_blocks; | |
| 50 T* m_spareBlock; // Used to avoid thrash at block boundaries. | |
| 51 }; | |
| 52 | |
| 53 template <typename T> BlockStack<T>::BlockStack() | |
| 54 : m_spareBlock(0) | |
| 55 { | |
| 56 } | |
| 57 | |
| 58 template <typename T> BlockStack<T>::~BlockStack() | |
| 59 { | |
| 60 if (m_spareBlock) | |
| 61 fastFree(m_spareBlock); | |
| 62 for (size_t i = 0; i < m_blocks.size(); ++i) | |
| 63 fastFree(m_blocks[i]); | |
| 64 } | |
| 65 | |
| 66 template <typename T> inline const Vector<T*>& BlockStack<T>::blocks() | |
| 67 { | |
| 68 return m_blocks; | |
| 69 } | |
| 70 | |
| 71 template <typename T> T* BlockStack<T>::grow() | |
| 72 { | |
| 73 T* block = m_spareBlock ? m_spareBlock : static_cast<T*>(fastMalloc(blockSiz
e)); | |
| 74 m_spareBlock = 0; | |
| 75 | |
| 76 m_blocks.append(block); | |
| 77 return block; | |
| 78 } | |
| 79 | |
| 80 template <typename T> void BlockStack<T>::shrink(T* newEnd) | |
| 81 { | |
| 82 ASSERT(newEnd != m_blocks.last() + blockLength); | |
| 83 m_spareBlock = m_blocks.last(); | |
| 84 m_blocks.removeLast(); | |
| 85 | |
| 86 while (m_blocks.last() + blockLength != newEnd) { | |
| 87 fastFree(m_blocks.last()); | |
| 88 m_blocks.removeLast(); | |
| 89 } | |
| 90 } | |
| 91 | |
| 92 } | |
| 93 | |
| 94 using WTF::BlockStack; | |
| 95 | |
| 96 #endif | |
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