source: NonGTP/Boost/boost/multi_index/detail/auto_space.hpp @ 857

Revision 857, 2.3 KB checked in by igarcia, 19 years ago (diff)
Line 
1/* Copyright 2003-2005 Joaquín M López Muñoz.
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/noncopyable.hpp>
20#include <memory>
21
22namespace boost{
23
24namespace multi_index{
25
26namespace detail{
27
28/* auto_space provides uninitialized space suitably to store
29 * a given number of elements of a given type.
30 */
31
32/* NB: it is not clear whether using an allocator to handle
33 * zero-sized arrays of elements is conformant or not. GCC 3.3.1
34 * and prior fail here, other stdlibs handle the issue gracefully.
35 * To be on the safe side, the case n==0 is given special treatment.
36 * References:
37 *   GCC Bugzilla, "standard allocator crashes when deallocating segment
38 *    "of zero length", http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14176
39 *   C++ Standard Library Defect Report List (Revision 28), issue 199
40 *     "What does allocate(0) return?",
41 *     http://anubis.dkuug.dk/jtc1/sc22/wg21/docs/lwg-defects.html#199
42 */
43
44template<typename T,typename Allocator=std::allocator<T> >
45struct auto_space:private noncopyable
46{
47  explicit auto_space(const Allocator& al=Allocator(),std::size_t n=1):
48  al_(al),n_(n),data_(n_?al_.allocate(n_):0)
49  {}
50
51  ~auto_space()
52  {
53    if(n_)al_.deallocate(data_,n_);
54  }
55
56  T* data()const{return data_;}
57
58  void swap(auto_space& x)
59  {
60    std::swap(n_,x.n_);
61    std::swap(data_,x.data_);
62  }
63   
64private:
65  typename boost::detail::allocator::rebind_to<
66    Allocator,T>::type                          al_;
67  std::size_t                                   n_;
68  T*                                            data_;
69};
70
71template<typename T,typename Allocator>
72void swap(auto_space<T,Allocator>& x,auto_space<T,Allocator>& y)
73{
74  x.swap(y);
75}
76
77} /* namespace multi_index::detail */
78
79} /* namespace multi_index */
80
81} /* namespace boost */
82
83#endif
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