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/* Copyright 2003-2013 Joaquin M Lopez Munoz.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* See http://www.boost.org/libs/multi_index for library home page.
*/
#ifndef BOOST_MULTI_INDEX_DETAIL_AUTO_SPACE_HPP
#define BOOST_MULTI_INDEX_DETAIL_AUTO_SPACE_HPP
#if defined(_MSC_VER)
#pragma once
#endif
#include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
#include <algorithm>
#include <boost/detail/allocator_utilities.hpp>
#include <boost/multi_index/detail/adl_swap.hpp>
#include <boost/noncopyable.hpp>
#include <memory>
namespace boost{
namespace multi_index{
namespace detail{
/* auto_space provides uninitialized space suitably to store
* a given number of elements of a given type.
*/
/* NB: it is not clear whether using an allocator to handle
* zero-sized arrays of elements is conformant or not. GCC 3.3.1
* and prior fail here, other stdlibs handle the issue gracefully.
* To be on the safe side, the case n==0 is given special treatment.
* References:
* GCC Bugzilla, "standard allocator crashes when deallocating segment
* "of zero length", http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14176
* C++ Standard Library Defect Report List (Revision 28), issue 199
* "What does allocate(0) return?",
* http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#199
*/
template<typename T,typename Allocator=std::allocator<T> >
struct auto_space:private noncopyable
{
typedef typename boost::detail::allocator::rebind_to<
Allocator,T
>::type::pointer pointer;
explicit auto_space(const Allocator& al=Allocator(),std::size_t n=1):
al_(al),n_(n),data_(n_?al_.allocate(n_):pointer(0))
{}
~auto_space()
{
if(n_)al_.deallocate(data_,n_);
}
Allocator get_allocator()const{return al_;}
pointer data()const{return data_;}
void swap(auto_space& x)
{
if(al_!=x.al_)adl_swap(al_,x.al_);
std::swap(n_,x.n_);
std::swap(data_,x.data_);
}
private:
typename boost::detail::allocator::rebind_to<
Allocator,T>::type al_;
std::size_t n_;
pointer data_;
};
template<typename T,typename Allocator>
void swap(auto_space<T,Allocator>& x,auto_space<T,Allocator>& y)
{
x.swap(y);
}
} /* namespace multi_index::detail */
} /* namespace multi_index */
} /* namespace boost */
#endif
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