1 | |
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2 | // (C) Copyright Steve Cleary, Beman Dawes, Howard Hinnant & 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_IS_EMPTY_HPP_INCLUDED |
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10 | #define BOOST_TT_IS_EMPTY_HPP_INCLUDED |
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11 | |
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12 | #include <boost/type_traits/is_convertible.hpp> |
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13 | #include <boost/type_traits/detail/ice_or.hpp> |
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14 | #include <boost/type_traits/config.hpp> |
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15 | #include <boost/type_traits/intrinsics.hpp> |
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16 | |
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17 | #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION |
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18 | # include <boost/type_traits/remove_cv.hpp> |
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19 | # include <boost/type_traits/is_class.hpp> |
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20 | # include <boost/type_traits/add_reference.hpp> |
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21 | #else |
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22 | # include <boost/type_traits/is_reference.hpp> |
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23 | # include <boost/type_traits/is_pointer.hpp> |
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24 | # include <boost/type_traits/is_member_pointer.hpp> |
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25 | # include <boost/type_traits/is_array.hpp> |
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26 | # include <boost/type_traits/is_void.hpp> |
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27 | # include <boost/type_traits/detail/ice_and.hpp> |
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28 | # include <boost/type_traits/detail/ice_not.hpp> |
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29 | #endif |
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30 | |
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31 | // should be always the last #include directive |
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32 | #include <boost/type_traits/detail/bool_trait_def.hpp> |
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33 | |
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34 | namespace boost { |
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35 | |
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36 | namespace detail { |
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37 | |
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38 | #ifndef BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION |
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39 | |
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40 | #ifdef BOOST_MSVC |
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41 | #pragma warning(push) |
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42 | #pragma warning(disable:4624) // destructor could not be generated |
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43 | #endif |
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44 | |
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45 | template <typename T> |
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46 | struct empty_helper_t1 : public T |
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47 | { |
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48 | empty_helper_t1(); // hh compiler bug workaround |
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49 | int i[256]; |
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50 | private: |
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51 | // suppress compiler warnings: |
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52 | empty_helper_t1(const empty_helper_t1&); |
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53 | empty_helper_t1& operator=(const empty_helper_t1&); |
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54 | }; |
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55 | |
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56 | #ifdef BOOST_MSVC |
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57 | #pragma warning(pop) |
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58 | #endif |
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59 | |
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60 | struct empty_helper_t2 { int i[256]; }; |
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61 | |
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62 | #if !BOOST_WORKAROUND(__BORLANDC__, < 0x600) |
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63 | |
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64 | template <typename T, bool is_a_class = false> |
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65 | struct empty_helper |
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66 | { |
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67 | BOOST_STATIC_CONSTANT(bool, value = false); |
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68 | }; |
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69 | |
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70 | template <typename T> |
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71 | struct empty_helper<T, true> |
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72 | { |
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73 | BOOST_STATIC_CONSTANT( |
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74 | bool, value = (sizeof(empty_helper_t1<T>) == sizeof(empty_helper_t2)) |
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75 | ); |
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76 | }; |
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77 | |
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78 | template <typename T> |
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79 | struct is_empty_impl |
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80 | { |
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81 | typedef typename remove_cv<T>::type cvt; |
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82 | BOOST_STATIC_CONSTANT( |
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83 | bool, value = ( |
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84 | ::boost::type_traits::ice_or< |
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85 | ::boost::detail::empty_helper<cvt,::boost::is_class<T>::value>::value |
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86 | , BOOST_IS_EMPTY(cvt) |
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87 | >::value |
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88 | )); |
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89 | }; |
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90 | |
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91 | #else // __BORLANDC__ |
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92 | |
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93 | template <typename T, bool is_a_class, bool convertible_to_int> |
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94 | struct empty_helper |
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95 | { |
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96 | BOOST_STATIC_CONSTANT(bool, value = false); |
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97 | }; |
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98 | |
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99 | template <typename T> |
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100 | struct empty_helper<T, true, false> |
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101 | { |
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102 | BOOST_STATIC_CONSTANT(bool, value = ( |
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103 | sizeof(empty_helper_t1<T>) == sizeof(empty_helper_t2) |
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104 | )); |
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105 | }; |
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106 | |
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107 | template <typename T> |
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108 | struct is_empty_impl |
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109 | { |
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110 | typedef typename remove_cv<T>::type cvt; |
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111 | typedef typename add_reference<T>::type r_type; |
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112 | |
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113 | BOOST_STATIC_CONSTANT( |
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114 | bool, value = ( |
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115 | ::boost::type_traits::ice_or< |
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116 | ::boost::detail::empty_helper< |
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117 | cvt |
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118 | , ::boost::is_class<T>::value |
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119 | , ::boost::is_convertible< r_type,int>::value |
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120 | >::value |
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121 | , BOOST_IS_EMPTY(cvt) |
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122 | >::value)); |
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123 | }; |
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124 | |
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125 | #endif // __BORLANDC__ |
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126 | |
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127 | #else // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION |
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128 | |
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129 | #ifdef BOOST_MSVC6_MEMBER_TEMPLATES |
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130 | |
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131 | template <typename T> |
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132 | struct empty_helper_t1 : public T |
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133 | { |
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134 | empty_helper_t1(); |
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135 | int i[256]; |
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136 | }; |
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137 | |
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138 | struct empty_helper_t2 { int i[256]; }; |
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139 | |
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140 | template <typename T> |
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141 | struct empty_helper_base |
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142 | { |
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143 | enum { value = (sizeof(empty_helper_t1<T>) == sizeof(empty_helper_t2)) }; |
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144 | }; |
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145 | |
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146 | template <typename T> |
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147 | struct empty_helper_nonbase |
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148 | { |
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149 | enum { value = false }; |
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150 | }; |
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151 | |
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152 | template <bool base> |
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153 | struct empty_helper_chooser |
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154 | { |
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155 | template <typename T> struct result_ |
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156 | { |
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157 | typedef empty_helper_nonbase<T> type; |
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158 | }; |
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159 | }; |
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160 | |
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161 | template <> |
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162 | struct empty_helper_chooser<true> |
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163 | { |
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164 | template <typename T> struct result_ |
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165 | { |
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166 | typedef empty_helper_base<T> type; |
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167 | }; |
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168 | }; |
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169 | |
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170 | template <typename T> |
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171 | struct is_empty_impl |
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172 | { |
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173 | typedef ::boost::detail::empty_helper_chooser< |
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174 | ::boost::type_traits::ice_and< |
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175 | ::boost::type_traits::ice_not< ::boost::is_reference<T>::value >::value, |
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176 | ::boost::type_traits::ice_not< ::boost::is_convertible<T,double>::value >::value, |
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177 | ::boost::type_traits::ice_not< ::boost::is_pointer<T>::value >::value, |
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178 | ::boost::type_traits::ice_not< ::boost::is_member_pointer<T>::value >::value, |
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179 | ::boost::type_traits::ice_not< ::boost::is_array<T>::value >::value, |
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180 | ::boost::type_traits::ice_not< ::boost::is_void<T>::value >::value, |
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181 | ::boost::type_traits::ice_not< |
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182 | ::boost::is_convertible<T,void const volatile*>::value |
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183 | >::value |
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184 | >::value > chooser; |
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185 | |
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186 | typedef typename chooser::template result_<T> result; |
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187 | typedef typename result::type eh_type; |
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188 | |
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189 | BOOST_STATIC_CONSTANT(bool, value = |
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190 | (::boost::type_traits::ice_or<eh_type::value, BOOST_IS_EMPTY(T)>::value)); |
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191 | }; |
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192 | |
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193 | #else |
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194 | |
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195 | template <typename T> struct is_empty_impl |
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196 | { |
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197 | BOOST_STATIC_CONSTANT(bool, value = BOOST_IS_EMPTY(T)); |
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198 | }; |
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199 | |
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200 | #endif // BOOST_MSVC6_MEMBER_TEMPLATES |
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201 | |
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202 | #endif // BOOST_NO_TEMPLATE_PARTIAL_SPECIALIZATION |
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203 | |
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204 | // these help when the compiler has no partial specialization support: |
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205 | BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void,false) |
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206 | #ifndef BOOST_NO_CV_VOID_SPECIALIZATIONS |
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207 | BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void const,false) |
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208 | BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void volatile,false) |
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209 | BOOST_TT_AUX_BOOL_TRAIT_IMPL_SPEC1(is_empty,void const volatile,false) |
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210 | #endif |
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211 | |
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212 | } // namespace detail |
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213 | |
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214 | BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_empty,T,::boost::detail::is_empty_impl<T>::value) |
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215 | |
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216 | } // namespace boost |
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217 | |
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218 | #include <boost/type_traits/detail/bool_trait_undef.hpp> |
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219 | |
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220 | #endif // BOOST_TT_IS_EMPTY_HPP_INCLUDED |
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221 | |
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