ceph/src/boost/boost/type_traits/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_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
  25 namespace boost {
  26
  27 namespace detail { namespace aligned_storage {
  28
  29 BOOST_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 //
  37 template <
  38       std::size_t size_
  39     , std::size_t alignment_
  40 >
  41 struct 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 };
  51 template <std::size_t size>
  52 struct 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
  62 template< std::size_t alignment_ >
  63 struct aligned_storage_imp<0u,alignment_>
  64 {
  65     /* intentionally empty */
  66     void* address() const { return 0; }
  67 };
  68
  69 }} // namespace detail::aligned_storage
  70
  71 template <
  72       std::size_t size_
  73     , std::size_t alignment_ = std::size_t(-1)
  74 >
  75 class 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
  84 public: // 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
 101 private: // noncopyable
 102
 103     aligned_storage(const aligned_storage&);
 104     aligned_storage& operator=(const aligned_storage&);
 105
 106 public: // structors
 107
 108     aligned_storage()
 109     {
 110     }
 111
 112     ~aligned_storage()
 113     {
 114     }
 115
 116 public: // 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 //
 133 template <std::size_t size_, std::size_t alignment_>
 134 struct 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