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Diffstat (limited to 'Source/JavaScriptCore/wtf/BlockStack.h')
-rw-r--r-- | Source/JavaScriptCore/wtf/BlockStack.h | 95 |
1 files changed, 95 insertions, 0 deletions
diff --git a/Source/JavaScriptCore/wtf/BlockStack.h b/Source/JavaScriptCore/wtf/BlockStack.h new file mode 100644 index 0000000..a4d7425 --- /dev/null +++ b/Source/JavaScriptCore/wtf/BlockStack.h @@ -0,0 +1,95 @@ +/* + * Copyright (C) 2011 Apple Inc. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, + * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS + * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF + * THE POSSIBILITY OF SUCH DAMAGE. + */ + +#ifndef BlockStack_h +#define BlockStack_h + +#include <wtf/Assertions.h> +#include <wtf/Vector.h> + +namespace WTF { + +template <typename T> class BlockStack { +public: + static const size_t blockSize = 4096; + static const size_t blockLength = blockSize / sizeof(T); + + BlockStack(); + ~BlockStack(); + + T* grow(); + void shrink(T*); + + const Vector<T*>& blocks(); + +private: + Vector<T*> m_blocks; + T* m_spareBlock; // Used to avoid thrash at block boundaries. +}; + +template <typename T> BlockStack<T>::BlockStack() + : m_spareBlock(0) +{ +} + +template <typename T> BlockStack<T>::~BlockStack() +{ + if (m_spareBlock) + free(m_spareBlock); + for (size_t i = 0; i < m_blocks.size(); ++i) + free(m_blocks[i]); +} + +template <typename T> inline const Vector<T*>& BlockStack<T>::blocks() +{ + return m_blocks; +} + +template <typename T> T* BlockStack<T>::grow() +{ + T* block = m_spareBlock ? m_spareBlock : static_cast<T*>(malloc(blockSize)); + m_spareBlock = 0; + + m_blocks.append(block); + return block; +} + +template <typename T> void BlockStack<T>::shrink(T* newEnd) +{ + ASSERT(newEnd != m_blocks.last() + blockLength); + m_spareBlock = m_blocks.last(); + m_blocks.removeLast(); + + while (m_blocks.last() + blockLength != newEnd) { + free(m_blocks.last()); + m_blocks.removeLast(); + } +} + +} + +using WTF::BlockStack; + +#endif |