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1 //-----------------------------------------------------------------------------
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2 // boost aligned_storage.hpp header file
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3 // See http://www.boost.org for updates, documentation, and revision history.
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4 //-----------------------------------------------------------------------------
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5 //
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6 // Copyright (c) 2002-2003
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7 // Eric Friedman, Itay Maman
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8 //
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9 // Distributed under the Boost Software License, Version 1.0. (See
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10 // accompanying file LICENSE_1_0.txt or copy at
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11 // http://www.boost.org/LICENSE_1_0.txt)
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12
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13 #ifndef BOOST_ALIGNED_STORAGE_HPP
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14 #define BOOST_ALIGNED_STORAGE_HPP
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15
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16 #include <cstddef> // for std::size_t
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17
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18 #include "boost/config.hpp"
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19 #include "boost/detail/workaround.hpp"
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20 #include "boost/type_traits/alignment_of.hpp"
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21 #include "boost/type_traits/type_with_alignment.hpp"
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22 #include "boost/type_traits/is_pod.hpp"
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23
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24 #include "boost/mpl/eval_if.hpp"
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25 #include "boost/mpl/identity.hpp"
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26
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27 #include "boost/type_traits/detail/bool_trait_def.hpp"
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28
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29 namespace boost {
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30
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31 namespace detail { namespace aligned_storage {
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32
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33 BOOST_STATIC_CONSTANT(
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34 std::size_t
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35 , alignment_of_max_align = ::boost::alignment_of<max_align>::value
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36 );
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37
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38 //
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39 // To be TR1 conforming this must be a POD type:
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40 //
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41 template <
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42 std::size_t size_
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43 , std::size_t alignment_
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44 >
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45 struct aligned_storage_imp
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46 {
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47 union data_t
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48 {
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49 char buf[size_];
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50
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51 typename ::boost::mpl::eval_if_c<
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52 alignment_ == std::size_t(-1)
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53 , ::boost::mpl::identity< ::boost::detail::max_align >
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54 , ::boost::type_with_alignment<alignment_>
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55 >::type align_;
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56 } data_;
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57 void* address() const { return const_cast<aligned_storage_imp*>(this); }
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58 };
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59
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60 template< std::size_t alignment_ >
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61 struct aligned_storage_imp<0u,alignment_>
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62 {
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63 /* intentionally empty */
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64 void* address() const { return 0; }
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65 };
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66
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67 }} // namespace detail::aligned_storage
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68
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69 template <
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70 std::size_t size_
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71 , std::size_t alignment_ = std::size_t(-1)
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72 >
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73 class aligned_storage :
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74 #ifndef __BORLANDC__
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75 private
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76 #else
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77 public
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78 #endif
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79 ::boost::detail::aligned_storage::aligned_storage_imp<size_, alignment_>
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80 {
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81
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82 public: // constants
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83
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84 typedef ::boost::detail::aligned_storage::aligned_storage_imp<size_, alignment_> type;
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85
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86 BOOST_STATIC_CONSTANT(
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87 std::size_t
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88 , size = size_
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89 );
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90 BOOST_STATIC_CONSTANT(
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91 std::size_t
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92 , alignment = (
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93 alignment_ == std::size_t(-1)
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94 ? ::boost::detail::aligned_storage::alignment_of_max_align
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95 : alignment_
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96 )
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97 );
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98
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99 private: // noncopyable
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100
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101 aligned_storage(const aligned_storage&);
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102 aligned_storage& operator=(const aligned_storage&);
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103
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104 public: // structors
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105
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106 aligned_storage()
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107 {
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108 }
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109
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110 ~aligned_storage()
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111 {
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112 }
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113
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114 public: // accessors
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115
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116 void* address()
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117 {
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118 return static_cast<type*>(this)->address();
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119 }
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120
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121 const void* address() const
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122 {
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123 return static_cast<const type*>(this)->address();
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124 }
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125 };
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126
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127 //
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128 // Make sure that is_pod recognises aligned_storage<>::type
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129 // as a POD (Note that aligned_storage<> itself is not a POD):
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130 //
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131 template <std::size_t size_, std::size_t alignment_>
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132 struct is_pod< ::boost::detail::aligned_storage::aligned_storage_imp<size_,alignment_> >
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133 BOOST_TT_AUX_BOOL_C_BASE(true)
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134 {
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135 BOOST_TT_AUX_BOOL_TRAIT_VALUE_DECL(true)
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136 };
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137
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138
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139 } // namespace boost
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140
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141 #include "boost/type_traits/detail/bool_trait_undef.hpp"
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142
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143 #endif // BOOST_ALIGNED_STORAGE_HPP
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