boost/boost/aligned_storage.hpp

   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_ALIGNED_STORAGE_HPP
  14 #define BOOST_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
  24 #include "boost/mpl/eval_if.hpp"
  25 #include "boost/mpl/identity.hpp"
  26
  27 #include "boost/type_traits/detail/bool_trait_def.hpp"
  28
  29 namespace boost {
  30
  31 namespace detail { namespace aligned_storage {
  32
  33 BOOST_STATIC_CONSTANT(
  34       std::size_t
  35     , alignment_of_max_align = ::boost::alignment_of<max_align>::value
  36     );
  37
  38 //
  39 // To be TR1 conforming this must be a POD type:
  40 //
  41 template <
  42       std::size_t size_
  43     , std::size_t alignment_
  44 >
  45 struct aligned_storage_imp
  46 {
  47     union data_t
  48     {
  49         char buf[size_];
  50
  51         typename mpl::eval_if_c<
  52               alignment_ == std::size_t(-1)
  53             , mpl::identity<detail::max_align>
  54             , type_with_alignment<alignment_>
  55             >::type align_;
  56     } data_;
  57 };
  58
  59 }} // namespace detail::aligned_storage
  60
  61 template <
  62       std::size_t size_
  63     , std::size_t alignment_ = std::size_t(-1)
  64 >
  65 class aligned_storage
  66 {
  67 private: // representation
  68
  69    detail::aligned_storage::aligned_storage_imp<size_, alignment_> data_;
  70
  71 public: // constants
  72
  73     typedef detail::aligned_storage::aligned_storage_imp<size_, alignment_> type;
  74
  75     BOOST_STATIC_CONSTANT(
  76           std::size_t
  77         , size = size_
  78         );
  79     BOOST_STATIC_CONSTANT(
  80           std::size_t
  81         , alignment = (
  82               alignment_ == std::size_t(-1)
  83             ? ::boost::detail::aligned_storage::alignment_of_max_align
  84             : alignment_
  85             )
  86         );
  87
  88 #if defined(__GNUC__) &&\
  89     (__GNUC__ >  3) ||\
  90     (__GNUC__ == 3 && (__GNUC_MINOR__ >  2 ||\
  91                       (__GNUC_MINOR__ == 2 && __GNUC_PATCHLEVEL__ >=3)))
  92
  93 private: // noncopyable
  94
  95     aligned_storage(const aligned_storage&);
  96     aligned_storage& operator=(const aligned_storage&);
  97
  98 #else // gcc less than 3.2.3
  99
 100 public: // _should_ be noncopyable, but GCC compiler emits error
 101
 102     aligned_storage(const aligned_storage&);
 103     aligned_storage& operator=(const aligned_storage&);
 104
 105 #endif // gcc < 3.2.3 workaround
 106
 107 public: // structors
 108
 109     aligned_storage()
 110     {
 111     }
 112
 113     ~aligned_storage()
 114     {
 115     }
 116
 117 public: // accessors
 118
 119     void* address()
 120     {
 121         return this;
 122     }
 123
 124 #if !BOOST_WORKAROUND(BOOST_MSVC, < 1300)
 125
 126     const void* address() const
 127     {
 128         return this;
 129     }
 130
 131 #else // MSVC6
 132
 133     const void* address() const;
 134
 135 #endif // MSVC6 workaround
 136
 137 };
 138
 139 #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)
 140
 141 // MSVC6 seems not to like inline functions with const void* returns, so we
 142 // declare the following here:
 143
 144 template <std::size_t S, std::size_t A>
 145 const void* aligned_storage<S,A>::address() const
 146 {
 147     return const_cast< aligned_storage<S,A>* >(this)->address();
 148 }
 149
 150 #endif // MSVC6 workaround
 151
 152 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION
 153 //
 154 // Make sure that is_pod recognises aligned_storage<>::type
 155 // as a POD (Note that aligned_storage<> itself is not a POD):
 156 //
 157 template <std::size_t size_, std::size_t alignment_>
 158 struct is_pod<boost::detail::aligned_storage::aligned_storage_imp<size_,alignment_> >
 159    BOOST_TT_AUX_BOOL_C_BASE(true)
 160 {
 161     BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(true)
 162 };
 163 #endif
 164
 165
 166 } // namespace boost
 167
 168 #include "boost/type_traits/detail/bool_trait_undef.hpp"
 169
 170 #endif // BOOST_ALIGNED_STORAGE_HPP