Chris@101: /* Copyright 2003-2013 Joaquin M Lopez Munoz.
Chris@16:  * Distributed under the Boost Software License, Version 1.0.
Chris@16:  * (See accompanying file LICENSE_1_0.txt or copy at
Chris@16:  * http://www.boost.org/LICENSE_1_0.txt)
Chris@16:  *
Chris@16:  * See http://www.boost.org/libs/multi_index for library home page.
Chris@16:  */
Chris@16: 
Chris@16: #ifndef BOOST_MULTI_INDEX_DETAIL_AUTO_SPACE_HPP
Chris@16: #define BOOST_MULTI_INDEX_DETAIL_AUTO_SPACE_HPP
Chris@16: 
Chris@101: #if defined(_MSC_VER)
Chris@16: #pragma once
Chris@16: #endif
Chris@16: 
Chris@16: #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
Chris@16: #include <algorithm>
Chris@16: #include <boost/detail/allocator_utilities.hpp>
Chris@16: #include <boost/multi_index/detail/adl_swap.hpp>
Chris@16: #include <boost/noncopyable.hpp>
Chris@16: #include <memory>
Chris@16: 
Chris@16: namespace boost{
Chris@16: 
Chris@16: namespace multi_index{
Chris@16: 
Chris@16: namespace detail{
Chris@16: 
Chris@16: /* auto_space provides uninitialized space suitably to store
Chris@16:  * a given number of elements of a given type.
Chris@16:  */
Chris@16: 
Chris@16: /* NB: it is not clear whether using an allocator to handle
Chris@16:  * zero-sized arrays of elements is conformant or not. GCC 3.3.1
Chris@16:  * and prior fail here, other stdlibs handle the issue gracefully.
Chris@16:  * To be on the safe side, the case n==0 is given special treatment.
Chris@16:  * References:
Chris@16:  *   GCC Bugzilla, "standard allocator crashes when deallocating segment
Chris@16:  *    "of zero length", http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14176
Chris@16:  *   C++ Standard Library Defect Report List (Revision 28), issue 199
Chris@16:  *     "What does allocate(0) return?",
Chris@101:  *     http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#199
Chris@16:  */
Chris@16: 
Chris@16: template<typename T,typename Allocator=std::allocator<T> >
Chris@16: struct auto_space:private noncopyable
Chris@16: {
Chris@101:   typedef typename boost::detail::allocator::rebind_to<
Chris@101:     Allocator,T
Chris@16:   >::type::pointer pointer;
Chris@16: 
Chris@16:   explicit auto_space(const Allocator& al=Allocator(),std::size_t n=1):
Chris@16:   al_(al),n_(n),data_(n_?al_.allocate(n_):pointer(0))
Chris@16:   {}
Chris@16: 
Chris@16:   ~auto_space()
Chris@16:   {
Chris@16:     if(n_)al_.deallocate(data_,n_);
Chris@16:   }
Chris@16: 
Chris@16:   Allocator get_allocator()const{return al_;}
Chris@16: 
Chris@16:   pointer data()const{return data_;}
Chris@16: 
Chris@16:   void swap(auto_space& x)
Chris@16:   {
Chris@16:     if(al_!=x.al_)adl_swap(al_,x.al_);
Chris@16:     std::swap(n_,x.n_);
Chris@16:     std::swap(data_,x.data_);
Chris@16:   }
Chris@16:     
Chris@16: private:
Chris@16:   typename boost::detail::allocator::rebind_to<
Chris@16:     Allocator,T>::type                          al_;
Chris@16:   std::size_t                                   n_;
Chris@16:   pointer                                       data_;
Chris@16: };
Chris@16: 
Chris@16: template<typename T,typename Allocator>
Chris@16: void swap(auto_space<T,Allocator>& x,auto_space<T,Allocator>& y)
Chris@16: {
Chris@16:   x.swap(y);
Chris@16: }
Chris@16: 
Chris@16: } /* namespace multi_index::detail */
Chris@16: 
Chris@16: } /* namespace multi_index */
Chris@16: 
Chris@16: } /* namespace boost */
Chris@16: 
Chris@16: #endif