src/thirdparty/boost_1_47_0/boost/multi_index/detail/auto_space.hpp

   1 /* Copyright 2003-2008 Joaquin M Lopez Munoz.
   2  * Distributed under the Boost Software License, Version 1.0.
   3  * (See accompanying file LICENSE_1_0.txt or copy at
   4  * http://www.boost.org/LICENSE_1_0.txt)
   5  *
   6  * See http://www.boost.org/libs/multi_index for library home page.
   7  */
   8
   9 #ifndef BOOST_MULTI_INDEX_DETAIL_AUTO_SPACE_HPP
  10 #define BOOST_MULTI_INDEX_DETAIL_AUTO_SPACE_HPP
  11
  12 #if defined(_MSC_VER)&&(_MSC_VER>=1200)
  13 #pragma once
  14 #endif
  15
  16 #include <boost/config.hpp> /* keep it first to prevent nasty warns in MSVC */
  17 #include <algorithm>
  18 #include <boost/detail/allocator_utilities.hpp>
  19 #include <boost/multi_index/detail/adl_swap.hpp>
  20 #include <boost/multi_index/detail/prevent_eti.hpp>
  21 #include <boost/noncopyable.hpp>
  22 #include <memory>
  23
  24 namespace boost{
  25
  26 namespace multi_index{
  27
  28 namespace detail{
  29
  30 /* auto_space provides uninitialized space suitably to store
  31  * a given number of elements of a given type.
  32  */
  33
  34 /* NB: it is not clear whether using an allocator to handle
  35  * zero-sized arrays of elements is conformant or not. GCC 3.3.1
  36  * and prior fail here, other stdlibs handle the issue gracefully.
  37  * To be on the safe side, the case n==0 is given special treatment.
  38  * References:
  39  *   GCC Bugzilla, "standard allocator crashes when deallocating segment
  40  *    "of zero length", http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14176
  41  *   C++ Standard Library Defect Report List (Revision 28), issue 199
  42  *     "What does allocate(0) return?",
  43  *     http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-defects.html#199
  44  */
  45
  46 template<typename T,typename Allocator=std::allocator<T> >
  47 struct auto_space:private noncopyable
  48 {
  49   typedef typename prevent_eti<
  50     Allocator,
  51     typename boost::detail::allocator::rebind_to<
  52       Allocator,T
  53     >::type
  54   >::type::pointer pointer;
  55
  56   explicit auto_space(const Allocator& al=Allocator(),std::size_t n=1):
  57   al_(al),n_(n),data_(n_?al_.allocate(n_):pointer(0))
  58   {}
  59
  60   ~auto_space()
  61   {
  62     if(n_)al_.deallocate(data_,n_);
  63   }
  64
  65   Allocator get_allocator()const{return al_;}
  66
  67   pointer data()const{return data_;}
  68
  69   void swap(auto_space& x)
  70   {
  71     if(al_!=x.al_)adl_swap(al_,x.al_);
  72     std::swap(n_,x.n_);
  73     std::swap(data_,x.data_);
  74   }
  75
  76 private:
  77   typename boost::detail::allocator::rebind_to<
  78     Allocator,T>::type                          al_;
  79   std::size_t                                   n_;
  80   pointer                                       data_;
  81 };
  82
  83 template<typename T,typename Allocator>
  84 void swap(auto_space<T,Allocator>& x,auto_space<T,Allocator>& y)
  85 {
  86   x.swap(y);
  87 }
  88
  89 } /* namespace multi_index::detail */
  90
  91 } /* namespace multi_index */
  92
  93 } /* namespace boost */
  94
  95 #endif