1//-----------------------------------------------------------------------------
2// boost aligned_storage.hpp header file
3// See http://www.boost.org for updates, documentation, and revision history.
4//-----------------------------------------------------------------------------
5//
6// Copyright (c) 2002-2003
7// Eric Friedman, Itay Maman
8//
9// Distributed under the Boost Software License, Version 1.0. (See
10// accompanying file LICENSE_1_0.txt or copy at
11// http://www.boost.org/LICENSE_1_0.txt)
12
13#ifndef BOOST_TT_ALIGNED_STORAGE_HPP
14#define BOOST_TT_ALIGNED_STORAGE_HPP
15
16#include <cstddef> // for std::size_t
17
18#include <boost/config.hpp>
19#include <boost/detail/workaround.hpp>
20#include <boost/type_traits/alignment_of.hpp>
21#include <boost/type_traits/type_with_alignment.hpp>
22#include <boost/type_traits/is_pod.hpp>
23#include <boost/type_traits/conditional.hpp>
24
25namespace boost {
26
27namespace detail { namespace aligned_storage {
28
29BOOST_STATIC_CONSTANT(
30 std::size_t
31 , alignment_of_max_align = ::boost::alignment_of<boost::detail::max_align>::value
32 );
33
34//
35// To be TR1 conforming this must be a POD type:
36//
37template <
38 std::size_t size_
39 , std::size_t alignment_
40>
41struct aligned_storage_imp
42{
43 union data_t
44 {
45 char buf[size_];
46
47 typename ::boost::type_with_alignment<alignment_>::type align_;
48 } data_;
49 void* address() const { return const_cast<aligned_storage_imp*>(this); }
50};
51template <std::size_t size>
52struct aligned_storage_imp<size, std::size_t(-1)>
53{
54 union data_t
55 {
56 char buf[size];
57 ::boost::detail::max_align align_;
58 } data_;
59 void* address() const { return const_cast<aligned_storage_imp*>(this); }
60};
61
62template< std::size_t alignment_ >
63struct aligned_storage_imp<0u,alignment_>
64{
65 /* intentionally empty */
66 void* address() const { return 0; }
67};
68
69}} // namespace detail::aligned_storage
70
71template <
72 std::size_t size_
73 , std::size_t alignment_ = std::size_t(-1)
74>
75class aligned_storage :
76#ifndef BOOST_BORLANDC
77 private
78#else
79 public
80#endif
81 ::boost::detail::aligned_storage::aligned_storage_imp<size_, alignment_>
82{
83
84public: // constants
85
86 typedef ::boost::detail::aligned_storage::aligned_storage_imp<size_, alignment_> type;
87
88 BOOST_STATIC_CONSTANT(
89 std::size_t
90 , size = size_
91 );
92 BOOST_STATIC_CONSTANT(
93 std::size_t
94 , alignment = (
95 alignment_ == std::size_t(-1)
96 ? ::boost::detail::aligned_storage::alignment_of_max_align
97 : alignment_
98 )
99 );
100
101private: // noncopyable
102
103 aligned_storage(const aligned_storage&);
104 aligned_storage& operator=(const aligned_storage&);
105
106public: // structors
107
108 aligned_storage()
109 {
110 }
111
112 ~aligned_storage()
113 {
114 }
115
116public: // accessors
117
118 void* address()
119 {
120 return static_cast<type*>(this)->address();
121 }
122
123 const void* address() const
124 {
125 return static_cast<const type*>(this)->address();
126 }
127};
128
129//
130// Make sure that is_pod recognises aligned_storage<>::type
131// as a POD (Note that aligned_storage<> itself is not a POD):
132//
133template <std::size_t size_, std::size_t alignment_>
134struct is_pod< ::boost::detail::aligned_storage::aligned_storage_imp<size_, alignment_> > : public true_type{};
135
136} // namespace boost
137
138#endif // BOOST_ALIGNED_STORAGE_HPP
139

source code of include/boost/type_traits/aligned_storage.hpp