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