122 lines
3.7 KiB
C++
122 lines
3.7 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* This file incorporates work covered by the following license notice:
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed
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* with this work for additional information regarding copyright
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* ownership. The ASF licenses this file to you under the Apache
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* License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.apache.org/licenses/LICENSE-2.0 .
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*/
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#ifndef INCLUDED_O3TL_VECTOR_POOL_HXX
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#define INCLUDED_O3TL_VECTOR_POOL_HXX
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#include <vector>
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namespace o3tl
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{
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namespace detail
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{
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template<typename ValueType, class Container> class simple_pool_impl :
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public Container
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{
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typedef typename Container::value_type value_type;
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std::ptrdiff_t mnFirstFreeIndex;
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public:
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simple_pool_impl() :
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mnFirstFreeIndex(-1)
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{}
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std::ptrdiff_t alloc()
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{
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return store(ValueType());
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}
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std::ptrdiff_t store(const ValueType& rCopy)
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{
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if( mnFirstFreeIndex != -1 )
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{
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std::ptrdiff_t nIdx=mnFirstFreeIndex;
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mnFirstFreeIndex = this->at(mnFirstFreeIndex).nextFree;
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this->at(nIdx).value = rCopy;
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this->at(nIdx).nextFree = -1;
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return nIdx;
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}
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else
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{
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this->push_back(value_type(rCopy));
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return this->size()-1;
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}
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}
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void free( std::ptrdiff_t nIdx )
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{
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this->at(nIdx).nextFree = mnFirstFreeIndex;
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mnFirstFreeIndex = nIdx;
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}
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const ValueType& get( std::ptrdiff_t nIdx ) const
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{
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return this->operator[](nIdx).value;
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}
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ValueType& get( std::ptrdiff_t nIdx )
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{
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return this->operator[](nIdx).value;
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}
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};
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template< typename ValueType > struct struct_from_value
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{
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struct type
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{
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type() :
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value(),
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nextFree(-1)
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{}
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explicit type( const ValueType& val ) :
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value(val),
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nextFree(-1)
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{}
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ValueType value;
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std::ptrdiff_t nextFree;
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};
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};
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}
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/** Simple vector-based memory pool allocator
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This template can be used to provide simple pooled memory
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allocation from a container class that adheres to the stl
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random access container concept. Note that alloc/free works
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with _indices_ into the container!
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@example
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<pre>
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vector_pool<type> myPool;
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int nIdx=myPool.alloc();
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myPool[nIdx] = myVal;
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... do stuff ...
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myPool.free(nIdx);
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</pre>
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*/
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template<typename ValueType> struct vector_pool :
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public detail::simple_pool_impl<ValueType,
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std::vector<typename detail::struct_from_value<ValueType>::type > >
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{};
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}
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#endif /* INCLUDED_O3TL_VECTOR_POOL_HXX */
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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