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The C and C++ Include Header Files
/usr/include/c++/13/ext/type_traits.h
$ cat -n /usr/include/c++/13/ext/type_traits.h 1 // -*- C++ -*- 2 3 // Copyright (C) 2005-2023 Free Software Foundation, Inc. 4 // 5 // This file is part of the GNU ISO C++ Library. This library is free 6 // software; you can redistribute it and/or modify it under the terms 7 // of the GNU General Public License as published by the Free Software 8 // Foundation; either version 3, or (at your option) any later 9 // version. 10 11 // This library is distributed in the hope that it will be useful, but 12 // WITHOUT ANY WARRANTY; without even the implied warranty of 13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 // General Public License for more details. 15 16 // Under Section 7 of GPL version 3, you are granted additional 17 // permissions described in the GCC Runtime Library Exception, version 18 // 3.1, as published by the Free Software Foundation. 19 20 // You should have received a copy of the GNU General Public License and 21 // a copy of the GCC Runtime Library Exception along with this program; 22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 23 // <http://www.gnu.org/licenses/>. 24 25 /** @file ext/type_traits.h 26 * This file is a GNU extension to the Standard C++ Library. 27 */ 28 29 #ifndef _EXT_TYPE_TRAITS 30 #define _EXT_TYPE_TRAITS 1 31 32 #pragma GCC system_header 33 34 #include <bits/c++config.h> 35 #include <bits/cpp_type_traits.h> 36 37 extern "C++" { 38 39 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 40 { 41 _GLIBCXX_BEGIN_NAMESPACE_VERSION 42 43 // Define a nested type if some predicate holds. 44 template<bool, typename> 45 struct __enable_if 46 { }; 47 48 template<typename _Tp> 49 struct __enable_if<true, _Tp> 50 { typedef _Tp __type; }; 51 52 53 // Conditional expression for types. If true, first, if false, second. 54 template<bool _Cond, typename _Iftrue, typename _Iffalse> 55 struct __conditional_type 56 { typedef _Iftrue __type; }; 57 58 template<typename _Iftrue, typename _Iffalse> 59 struct __conditional_type<false, _Iftrue, _Iffalse> 60 { typedef _Iffalse __type; }; 61 62 63 // Given an integral builtin type, return the corresponding unsigned type. 64 template<typename _Tp> 65 struct __add_unsigned 66 { 67 private: 68 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 69 70 public: 71 typedef typename __if_type::__type __type; 72 }; 73 74 template<> 75 struct __add_unsigned<char> 76 { typedef unsigned char __type; }; 77 78 template<> 79 struct __add_unsigned<signed char> 80 { typedef unsigned char __type; }; 81 82 template<> 83 struct __add_unsigned<short> 84 { typedef unsigned short __type; }; 85 86 template<> 87 struct __add_unsigned<int> 88 { typedef unsigned int __type; }; 89 90 template<> 91 struct __add_unsigned<long> 92 { typedef unsigned long __type; }; 93 94 template<> 95 struct __add_unsigned<long long> 96 { typedef unsigned long long __type; }; 97 98 // Declare but don't define. 99 template<> 100 struct __add_unsigned<bool>; 101 102 template<> 103 struct __add_unsigned<wchar_t>; 104 105 106 // Given an integral builtin type, return the corresponding signed type. 107 template<typename _Tp> 108 struct __remove_unsigned 109 { 110 private: 111 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 112 113 public: 114 typedef typename __if_type::__type __type; 115 }; 116 117 template<> 118 struct __remove_unsigned<char> 119 { typedef signed char __type; }; 120 121 template<> 122 struct __remove_unsigned<unsigned char> 123 { typedef signed char __type; }; 124 125 template<> 126 struct __remove_unsigned<unsigned short> 127 { typedef short __type; }; 128 129 template<> 130 struct __remove_unsigned<unsigned int> 131 { typedef int __type; }; 132 133 template<> 134 struct __remove_unsigned<unsigned long> 135 { typedef long __type; }; 136 137 template<> 138 struct __remove_unsigned<unsigned long long> 139 { typedef long long __type; }; 140 141 // Declare but don't define. 142 template<> 143 struct __remove_unsigned<bool>; 144 145 template<> 146 struct __remove_unsigned<wchar_t>; 147 148 149 // For use in string and vstring. 150 template<typename _Type> 151 _GLIBCXX_CONSTEXPR 152 inline bool 153 __is_null_pointer(_Type* __ptr) 154 { return __ptr == 0; } 155 156 template<typename _Type> 157 _GLIBCXX_CONSTEXPR 158 inline bool 159 __is_null_pointer(_Type) 160 { return false; } 161 162 #if __cplusplus >= 201103L 163 constexpr bool 164 __is_null_pointer(std::nullptr_t) 165 { return true; } 166 #endif 167 168 // For arithmetic promotions in <complex> and <cmath> 169 170 template<typename _Tp, bool = std::__is_integer<_Tp>::__value> 171 struct __promote 172 { typedef double __type; }; 173 174 // No nested __type member for non-integer non-floating point types, 175 // allows this type to be used for SFINAE to constrain overloads in 176 // <cmath> and <complex> to only the intended types. 177 template<typename _Tp> 178 struct __promote<_Tp, false> 179 { }; 180 181 template<> 182 struct __promote<long double> 183 { typedef long double __type; }; 184 185 template<> 186 struct __promote<double> 187 { typedef double __type; }; 188 189 template<> 190 struct __promote<float> 191 { typedef float __type; }; 192 193 #ifdef __STDCPP_FLOAT16_T__ 194 template<> 195 struct __promote<_Float16> 196 { typedef _Float16 __type; }; 197 #endif 198 199 #ifdef __STDCPP_FLOAT32_T__ 200 template<> 201 struct __promote<_Float32> 202 { typedef _Float32 __type; }; 203 #endif 204 205 #ifdef __STDCPP_FLOAT64_T__ 206 template<> 207 struct __promote<_Float64> 208 { typedef _Float64 __type; }; 209 #endif 210 211 #ifdef __STDCPP_FLOAT128_T__ 212 template<> 213 struct __promote<_Float128> 214 { typedef _Float128 __type; }; 215 #endif 216 217 #ifdef __STDCPP_BFLOAT16_T__ 218 template<> 219 struct __promote<__gnu_cxx::__bfloat16_t> 220 { typedef __gnu_cxx::__bfloat16_t __type; }; 221 #endif 222 223 #if __cpp_fold_expressions 224 225 template<typename... _Tp> 226 using __promoted_t = decltype((typename __promote<_Tp>::__type(0) + ...)); 227 228 // Deducing the promoted type is done by __promoted_t<_Tp...>, 229 // then __promote is used to provide the nested __type member. 230 template<typename _Tp, typename _Up> 231 using __promote_2 = __promote<__promoted_t<_Tp, _Up>>; 232 233 template<typename _Tp, typename _Up, typename _Vp> 234 using __promote_3 = __promote<__promoted_t<_Tp, _Up, _Vp>>; 235 236 template<typename _Tp, typename _Up, typename _Vp, typename _Wp> 237 using __promote_4 = __promote<__promoted_t<_Tp, _Up, _Vp, _Wp>>; 238 239 #else 240 241 template<typename _Tp, typename _Up, 242 typename _Tp2 = typename __promote<_Tp>::__type, 243 typename _Up2 = typename __promote<_Up>::__type> 244 struct __promote_2 245 { 246 typedef __typeof__(_Tp2() + _Up2()) __type; 247 }; 248 249 template<typename _Tp, typename _Up, typename _Vp, 250 typename _Tp2 = typename __promote<_Tp>::__type, 251 typename _Up2 = typename __promote<_Up>::__type, 252 typename _Vp2 = typename __promote<_Vp>::__type> 253 struct __promote_3 254 { 255 typedef __typeof__(_Tp2() + _Up2() + _Vp2()) __type; 256 }; 257 258 template<typename _Tp, typename _Up, typename _Vp, typename _Wp, 259 typename _Tp2 = typename __promote<_Tp>::__type, 260 typename _Up2 = typename __promote<_Up>::__type, 261 typename _Vp2 = typename __promote<_Vp>::__type, 262 typename _Wp2 = typename __promote<_Wp>::__type> 263 struct __promote_4 264 { 265 typedef __typeof__(_Tp2() + _Up2() + _Vp2() + _Wp2()) __type; 266 }; 267 #endif 268 269 _GLIBCXX_END_NAMESPACE_VERSION 270 } // namespace 271 } // extern "C++" 272 273 #endif
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