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95 lines
2.6 KiB
95 lines
2.6 KiB
/* Copyright 2003-2008 Joaquin M Lopez Munoz. |
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* Distributed under the Boost Software License, Version 1.0. |
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* (See accompanying file LICENSE_1_0.txt or copy at |
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* http://www.boost.org/LICENSE_1_0.txt) |
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* |
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* See http://www.boost.org/libs/multi_index for library home page. |
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*/ |
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#ifndef BOOST_MULTI_INDEX_DETAIL_AUTO_SPACE_HPP |
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#define BOOST_MULTI_INDEX_DETAIL_AUTO_SPACE_HPP |
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#if defined(_MSC_VER)&&(_MSC_VER>=1200) |
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#pragma once |
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#endif |
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#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */ |
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#include <algorithm> |
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#include <boost/detail/allocator_utilities.hpp> |
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#include <boost/multi_index/detail/adl_swap.hpp> |
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#include <boost/multi_index/detail/prevent_eti.hpp> |
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#include <boost/noncopyable.hpp> |
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#include <memory> |
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namespace boost{ |
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namespace multi_index{ |
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namespace detail{ |
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/* auto_space provides uninitialized space suitably to store |
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* a given number of elements of a given type. |
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*/ |
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/* NB: it is not clear whether using an allocator to handle |
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* zero-sized arrays of elements is conformant or not. GCC 3.3.1 |
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* and prior fail here, other stdlibs handle the issue gracefully. |
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* To be on the safe side, the case n==0 is given special treatment. |
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* References: |
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* GCC Bugzilla, "standard allocator crashes when deallocating segment |
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* "of zero length", http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14176 |
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* C++ Standard Library Defect Report List (Revision 28), issue 199 |
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* "What does allocate(0) return?", |
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* http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-defects.html#199 |
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*/ |
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template<typename T,typename Allocator=std::allocator<T> > |
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struct auto_space:private noncopyable |
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{ |
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typedef typename prevent_eti< |
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Allocator, |
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typename boost::detail::allocator::rebind_to< |
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Allocator,T |
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>::type |
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>::type::pointer pointer; |
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explicit auto_space(const Allocator& al=Allocator(),std::size_t n=1): |
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al_(al),n_(n),data_(n_?al_.allocate(n_):pointer(0)) |
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{} |
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~auto_space() |
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{ |
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if(n_)al_.deallocate(data_,n_); |
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} |
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Allocator get_allocator()const{return al_;} |
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pointer data()const{return data_;} |
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void swap(auto_space& x) |
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{ |
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if(al_!=x.al_)adl_swap(al_,x.al_); |
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std::swap(n_,x.n_); |
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std::swap(data_,x.data_); |
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} |
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private: |
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typename boost::detail::allocator::rebind_to< |
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Allocator,T>::type al_; |
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std::size_t n_; |
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pointer data_; |
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}; |
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template<typename T,typename Allocator> |
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void swap(auto_space<T,Allocator>& x,auto_space<T,Allocator>& y) |
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{ |
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x.swap(y); |
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} |
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} /* namespace multi_index::detail */ |
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} /* namespace multi_index */ |
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} /* namespace boost */ |
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#endif
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