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The C and C++ Include Header Files
cat -n /usr/include/c++/15/ext/type_traits.h
1 // -*- C++ -*- 2 3 // Copyright (C) 2005-2025 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 #ifdef _GLIBCXX_SYSHDR 33 #pragma GCC system_header 34 #endif 35 36 #include <bits/c++config.h> 37 #include <bits/cpp_type_traits.h> 38 39 #pragma GCC diagnostic push 40 #pragma GCC diagnostic ignored "-Wlong-long" 41 42 extern "C++" { 43 44 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 45 { 46 _GLIBCXX_BEGIN_NAMESPACE_VERSION 47 48 // Define a nested type if some predicate holds. 49 template<bool, typename> 50 struct __enable_if 51 { }; 52 53 template<typename _Tp> 54 struct __enable_if<true, _Tp> 55 { typedef _Tp __type; }; 56 57 58 // Conditional expression for types. If true, first, if false, second. 59 template<bool _Cond, typename _Iftrue, typename _Iffalse> 60 struct __conditional_type 61 { typedef _Iftrue __type; }; 62 63 template<typename _Iftrue, typename _Iffalse> 64 struct __conditional_type<false, _Iftrue, _Iffalse> 65 { typedef _Iffalse __type; }; 66 67 68 // Given an integral builtin type, return the corresponding unsigned type. 69 template<typename _Tp> 70 struct __add_unsigned 71 { 72 private: 73 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 74 75 public: 76 typedef typename __if_type::__type __type; 77 }; 78 79 template<> 80 struct __add_unsigned<char> 81 { typedef unsigned char __type; }; 82 83 template<> 84 struct __add_unsigned<signed char> 85 { typedef unsigned char __type; }; 86 87 template<> 88 struct __add_unsigned<short> 89 { typedef unsigned short __type; }; 90 91 template<> 92 struct __add_unsigned<int> 93 { typedef unsigned int __type; }; 94 95 template<> 96 struct __add_unsigned<long> 97 { typedef unsigned long __type; }; 98 99 template<> 100 struct __add_unsigned<long long> 101 { typedef unsigned long long __type; }; 102 103 // Declare but don't define. 104 template<> 105 struct __add_unsigned<bool>; 106 107 template<> 108 struct __add_unsigned<wchar_t>; 109 110 111 // Given an integral builtin type, return the corresponding signed type. 112 template<typename _Tp> 113 struct __remove_unsigned 114 { 115 private: 116 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 117 118 public: 119 typedef typename __if_type::__type __type; 120 }; 121 122 template<> 123 struct __remove_unsigned<char> 124 { typedef signed char __type; }; 125 126 template<> 127 struct __remove_unsigned<unsigned char> 128 { typedef signed char __type; }; 129 130 template<> 131 struct __remove_unsigned<unsigned short> 132 { typedef short __type; }; 133 134 template<> 135 struct __remove_unsigned<unsigned int> 136 { typedef int __type; }; 137 138 template<> 139 struct __remove_unsigned<unsigned long> 140 { typedef long __type; }; 141 142 template<> 143 struct __remove_unsigned<unsigned long long> 144 { typedef long long __type; }; 145 146 // Declare but don't define. 147 template<> 148 struct __remove_unsigned<bool>; 149 150 template<> 151 struct __remove_unsigned<wchar_t>; 152 153 154 // For use in string and vstring. 155 template<typename _Type> 156 _GLIBCXX_CONSTEXPR 157 inline bool 158 __is_null_pointer(_Type* __ptr) 159 { return __ptr == 0; } 160 161 template<typename _Type> 162 _GLIBCXX_CONSTEXPR 163 inline bool 164 __is_null_pointer(_Type) 165 { return false; } 166 167 #if __cplusplus >= 201103L 168 constexpr bool 169 __is_null_pointer(std::nullptr_t) 170 { return true; } 171 #endif 172 173 // For arithmetic promotions in <complex> and <cmath> 174 175 template<typename _Tp, bool = std::__is_integer<_Tp>::__value> 176 struct __promote 177 { typedef double __type; }; 178 179 // No nested __type member for non-integer non-floating point types, 180 // allows this type to be used for SFINAE to constrain overloads in 181 // <cmath> and <complex> to only the intended types. 182 template<typename _Tp> 183 struct __promote<_Tp, false> 184 { }; 185 186 template<> 187 struct __promote<long double> 188 { typedef long double __type; }; 189 190 template<> 191 struct __promote<double> 192 { typedef double __type; }; 193 194 template<> 195 struct __promote<float> 196 { typedef float __type; }; 197 198 #ifdef __STDCPP_FLOAT16_T__ 199 template<> 200 struct __promote<_Float16> 201 { typedef _Float16 __type; }; 202 #endif 203 204 #ifdef __STDCPP_FLOAT32_T__ 205 template<> 206 struct __promote<_Float32> 207 { typedef _Float32 __type; }; 208 #endif 209 210 #ifdef __STDCPP_FLOAT64_T__ 211 template<> 212 struct __promote<_Float64> 213 { typedef _Float64 __type; }; 214 #endif 215 216 #ifdef __STDCPP_FLOAT128_T__ 217 template<> 218 struct __promote<_Float128> 219 { typedef _Float128 __type; }; 220 #endif 221 222 #ifdef __STDCPP_BFLOAT16_T__ 223 template<> 224 struct __promote<__gnu_cxx::__bfloat16_t> 225 { typedef __gnu_cxx::__bfloat16_t __type; }; 226 #endif 227 228 #if __cpp_fold_expressions 229 230 template<typename... _Tp> 231 using __promoted_t = decltype((typename __promote<_Tp>::__type(0) + ...)); 232 233 // Deducing the promoted type is done by __promoted_t<_Tp...>, 234 // then __promote is used to provide the nested __type member. 235 template<typename _Tp, typename _Up> 236 using __promote_2 = __promote<__promoted_t<_Tp, _Up>>; 237 238 template<typename _Tp, typename _Up, typename _Vp> 239 using __promote_3 = __promote<__promoted_t<_Tp, _Up, _Vp>>; 240 241 template<typename _Tp, typename _Up, typename _Vp, typename _Wp> 242 using __promote_4 = __promote<__promoted_t<_Tp, _Up, _Vp, _Wp>>; 243 244 #else 245 246 template<typename _Tp, typename _Up, 247 typename _Tp2 = typename __promote<_Tp>::__type, 248 typename _Up2 = typename __promote<_Up>::__type> 249 struct __promote_2 250 { 251 typedef __typeof__(_Tp2() + _Up2()) __type; 252 }; 253 254 template<typename _Tp, typename _Up, typename _Vp, 255 typename _Tp2 = typename __promote<_Tp>::__type, 256 typename _Up2 = typename __promote<_Up>::__type, 257 typename _Vp2 = typename __promote<_Vp>::__type> 258 struct __promote_3 259 { 260 typedef __typeof__(_Tp2() + _Up2() + _Vp2()) __type; 261 }; 262 263 template<typename _Tp, typename _Up, typename _Vp, typename _Wp, 264 typename _Tp2 = typename __promote<_Tp>::__type, 265 typename _Up2 = typename __promote<_Up>::__type, 266 typename _Vp2 = typename __promote<_Vp>::__type, 267 typename _Wp2 = typename __promote<_Wp>::__type> 268 struct __promote_4 269 { 270 typedef __typeof__(_Tp2() + _Up2() + _Vp2() + _Wp2()) __type; 271 }; 272 #endif 273 274 _GLIBCXX_END_NAMESPACE_VERSION 275 } // namespace 276 } // extern "C++" 277 278 #pragma GCC diagnostic pop 279 280 #endif
