1 | |
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2 | // (C) Copyright John Maddock 2000. |
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3 | // Use, modification and distribution are subject to the Boost Software License, |
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4 | // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at |
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5 | // http://www.boost.org/LICENSE_1_0.txt). |
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6 | // |
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7 | // See http://www.boost.org/libs/type_traits for most recent version including documentation. |
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8 | |
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9 | #ifndef BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED |
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10 | #define BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED |
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11 | |
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12 | #include <boost/config.hpp> |
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13 | #include <cstddef> |
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14 | |
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15 | #include <boost/type_traits/intrinsics.hpp> |
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16 | // should be the last #include |
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17 | #include <boost/type_traits/detail/size_t_trait_def.hpp> |
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18 | |
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19 | #ifdef BOOST_MSVC |
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20 | # pragma warning(push) |
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21 | # pragma warning(disable: 4121 4512) // alignment is sensitive to packing |
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22 | #endif |
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23 | #if defined(__BORLANDC__) && (__BORLANDC__ < 0x600) |
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24 | #pragma option push -Vx- -Ve- |
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25 | #endif |
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26 | |
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27 | namespace boost { |
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28 | |
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29 | template <typename T> struct alignment_of; |
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30 | |
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31 | // get the alignment of some arbitrary type: |
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32 | namespace detail { |
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33 | |
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34 | #ifdef BOOST_MSVC |
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35 | #pragma warning(push) |
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36 | #pragma warning(disable:4324) // structure was padded due to __declspec(align()) |
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37 | #endif |
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38 | template <typename T> |
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39 | struct alignment_of_hack |
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40 | { |
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41 | char c; |
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42 | T t; |
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43 | alignment_of_hack(); |
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44 | }; |
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45 | #ifdef BOOST_MSVC |
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46 | #pragma warning(pop) |
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47 | #endif |
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48 | |
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49 | template <unsigned A, unsigned S> |
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50 | struct alignment_logic |
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51 | { |
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52 | BOOST_STATIC_CONSTANT(std::size_t, value = A < S ? A : S); |
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53 | }; |
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54 | |
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55 | |
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56 | template< typename T > |
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57 | struct alignment_of_impl |
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58 | { |
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59 | #if defined(BOOST_MSVC) && (BOOST_MSVC >= 1400) |
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60 | // |
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61 | // With MSVC both the native __alignof operator |
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62 | // and our own logic gets things wrong from time to time :-( |
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63 | // Using a combination of the two seems to make the most of a bad job: |
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64 | // |
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65 | BOOST_STATIC_CONSTANT(std::size_t, value = |
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66 | (::boost::detail::alignment_logic< |
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67 | sizeof(::boost::detail::alignment_of_hack<T>) - sizeof(T), |
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68 | __alignof(T) |
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69 | >::value)); |
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70 | #elif !defined(BOOST_ALIGNMENT_OF) |
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71 | BOOST_STATIC_CONSTANT(std::size_t, value = |
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72 | (::boost::detail::alignment_logic< |
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73 | sizeof(::boost::detail::alignment_of_hack<T>) - sizeof(T), |
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74 | sizeof(T) |
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75 | >::value)); |
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76 | #else |
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77 | // |
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78 | // We put this here, rather than in the definition of |
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79 | // alignment_of below, because MSVC's __alignof doesn't |
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80 | // always work in that context for some unexplained reason. |
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81 | // (See type_with_alignment tests for test cases). |
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82 | // |
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83 | BOOST_STATIC_CONSTANT(std::size_t, value = BOOST_ALIGNMENT_OF(T)); |
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84 | #endif |
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85 | }; |
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86 | |
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87 | } // namespace detail |
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88 | |
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89 | BOOST_TT_AUX_SIZE_T_TRAIT_DEF1(alignment_of,T,::boost::detail::alignment_of_impl<T>::value) |
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90 | |
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91 | // references have to be treated specially, assume |
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92 | // that a reference is just a special pointer: |
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93 | #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION |
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94 | template <typename T> |
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95 | struct alignment_of<T&> |
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96 | : alignment_of<T*> |
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97 | { |
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98 | }; |
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99 | #endif |
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100 | #ifdef __BORLANDC__ |
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101 | // long double gives an incorrect value of 10 (!) |
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102 | // unless we do this... |
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103 | struct long_double_wrapper{ long double ld; }; |
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104 | template<> struct alignment_of<long double> |
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105 | : public alignment_of<long_double_wrapper>{}; |
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106 | #endif |
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107 | |
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108 | // void has to be treated specially: |
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109 | BOOST_TT_AUX_SIZE_T_TRAIT_SPEC1(alignment_of,void,0) |
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110 | #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS |
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111 | BOOST_TT_AUX_SIZE_T_TRAIT_SPEC1(alignment_of,void const,0) |
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112 | BOOST_TT_AUX_SIZE_T_TRAIT_SPEC1(alignment_of,void volatile,0) |
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113 | BOOST_TT_AUX_SIZE_T_TRAIT_SPEC1(alignment_of,void const volatile,0) |
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114 | #endif |
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115 | |
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116 | } // namespace boost |
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117 | |
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118 | #if defined(__BORLANDC__) && (__BORLANDC__ < 0x600) |
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119 | #pragma option pop |
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120 | #endif |
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121 | #ifdef BOOST_MSVC |
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122 | # pragma warning(pop) |
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123 | #endif |
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124 | |
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125 | #include <boost/type_traits/detail/size_t_trait_undef.hpp> |
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126 | |
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127 | #endif // BOOST_TT_ALIGNMENT_OF_HPP_INCLUDED |
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128 | |
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