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 void* address() const { return const_cast<aligned_storage_imp*>(this); } 58 }; 59 60 template< std::size_t alignment_ > 61 struct aligned_storage_imp<0u,alignment_> 62 { 63 /* intentionally empty */ 64 void* address() const { return 0; } 65 }; 66 67 }} // namespace detail::aligned_storage 68 69 template < 70 std::size_t size_ 71 , std::size_t alignment_ = std::size_t(-1) 72 > 73 class aligned_storage : 74 #ifndef __BORLANDC__ 75 private 76 #else 77 public 78 #endif 79 detail::aligned_storage::aligned_storage_imp<size_, alignment_> 80 { 81 82 public: // constants 83 84 typedef detail::aligned_storage::aligned_storage_imp<size_, alignment_> type; 85 86 BOOST_STATIC_CONSTANT( 87 std::size_t 88 , size = size_ 89 ); 90 BOOST_STATIC_CONSTANT( 91 std::size_t 92 , alignment = ( 93 alignment_ == std::size_t(-1) 94 ? ::boost::detail::aligned_storage::alignment_of_max_align 95 : alignment_ 96 ) 97 ); 98 99 #if defined(__GNUC__) &&\ 100 (__GNUC__ > 3) ||\ 101 (__GNUC__ == 3 && (__GNUC_MINOR__ > 2 ||\ 102 (__GNUC_MINOR__ == 2 && __GNUC_PATCHLEVEL__ >=3))) 103 104 private: // noncopyable 105 106 aligned_storage(const aligned_storage&); 107 aligned_storage& operator=(const aligned_storage&); 108 109 #else // gcc less than 3.2.3 110 111 public: // _should_ be noncopyable, but GCC compiler emits error 112 113 aligned_storage(const aligned_storage&); 114 aligned_storage& operator=(const aligned_storage&); 115 116 #endif // gcc < 3.2.3 workaround 117 118 public: // structors 119 120 aligned_storage() 121 { 122 } 123 124 ~aligned_storage() 125 { 126 } 127 128 public: // accessors 129 130 void* address() 131 { 132 return static_cast<type*>(this)->address(); 133 } 134 135 #if !BOOST_WORKAROUND(BOOST_MSVC, < 1300) 136 137 const void* address() const 138 { 139 return static_cast<const type*>(this)->address(); 140 } 141 142 #else // MSVC6 143 144 const void* address() const; 145 146 #endif // MSVC6 workaround 147 148 }; 149 150 #if BOOST_WORKAROUND(BOOST_MSVC, < 1300) 151 152 // MSVC6 seems not to like inline functions with const void* returns, so we 153 // declare the following here: 154 155 template <std::size_t S, std::size_t A> 156 const void* aligned_storage<S,A>::address() const 157 { 158 return const_cast< aligned_storage<S,A>* >(this)->address(); 159 } 160 161 #endif // MSVC6 workaround 162 163 #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION 164 // 165 // Make sure that is_pod recognises aligned_storage<>::type 166 // as a POD (Note that aligned_storage<> itself is not a POD): 167 // 168 template <std::size_t size_, std::size_t alignment_> 169 struct is_pod<boost::detail::aligned_storage::aligned_storage_imp<size_,alignment_> > 170 BOOST_TT_AUX_BOOL_C_BASE(true) 171 { 172 BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(true) 173 }; 174 #endif 175 176 177 } // namespace boost 178 179 #include "boost/type_traits/detail/bool_trait_undef.hpp" 180 181 #endif // BOOST_ALIGNED_STORAGE_HPP 182
