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119 lines
3.1 KiB
C++
119 lines
3.1 KiB
C++
/*
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Copyright (C) 2010 Klarälvdalens Datakonsult AB,
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a KDAB Group company, info@kdab.net,
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author Stephen Kelly <stephen@kdab.com>
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This library is free software; you can redistribute it and/or modify it
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under the terms of the GNU Library General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at your
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option) any later version.
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This library is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
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License for more details.
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You should have received a copy of the GNU Library General Public License
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along with this library; see the file COPYING.LIB. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301, USA.
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*/
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#ifndef KVOIDPOINTERFACTORY_P_H
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#define KVOIDPOINTERFACTORY_P_H
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#include <vector>
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#include <cstdlib>
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#include <cstddef>
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#define DEFAULT_BLOCK_SIZE 256
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/**
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* @brief A Class for managing void pointers for use in QModelIndexes.
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*
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* This class creates void pointers pointing to individual blocks of memory.
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* The pointed-to memory contains zeros.
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*
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* Memory is allocated in blocks of size @p blockSize times sizeof(void*) at a time. The used
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* memory is automatically freed and can be cleared manually.
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*
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* The void pointers should not be dereferenced, but only used as a unique
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* identifier suitable for use with createIndex() and for comparison with other void pointers.
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*/
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template<std::size_t blockSize = DEFAULT_BLOCK_SIZE>
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class KVoidPointerFactory
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{
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// a class with size 1.
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class Bit { bool bit; };
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public:
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KVoidPointerFactory()
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: m_previousPointer(0),
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m_finalPointer(0)
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{
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}
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KVoidPointerFactory(const KVoidPointerFactory<blockSize> &other)
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{
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*this = other;
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}
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KVoidPointerFactory<blockSize>& operator=(const KVoidPointerFactory<blockSize> &other)
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{
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m_previousPointer = other.m_previousPointer;
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m_finalPointer = other.m_finalPointer;
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m_blocks = other.m_blocks;
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return *this;
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}
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~KVoidPointerFactory()
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{
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clear();
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}
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void clear()
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{
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typename std::vector<Bit*>::const_iterator it = m_blocks.begin();
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const typename std::vector<Bit*>::const_iterator end = m_blocks.end();
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for ( ; it != end; ++it)
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{
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free(*it);
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}
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m_blocks.clear();
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m_finalPointer = 0;
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m_previousPointer = 0;
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}
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void* createPointer() const
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{
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if (m_previousPointer == m_finalPointer)
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{
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static const std::size_t pointer_size = sizeof(Bit*);
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Bit * const bit = static_cast<Bit*>(calloc(blockSize, pointer_size));
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m_blocks.push_back(bit);
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m_finalPointer = bit + (blockSize * pointer_size) - 1;
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m_previousPointer = bit;
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return bit;
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}
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return ++m_previousPointer;
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}
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private:
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mutable std::vector<Bit *> m_blocks;
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mutable Bit *m_previousPointer;
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mutable Bit *m_finalPointer;
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};
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// Disable factory with 0 blockSize
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template<>
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class KVoidPointerFactory<0>
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{
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public:
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KVoidPointerFactory();
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void clear();
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void* createPointer();
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};
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#endif
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