1 // -*- C++ -*- 2 3 // Copyright (C) 2005-2018 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 inline bool 152 __is_null_pointer(_Type* __ptr) 153 { return __ptr == 0; } 154 155 template<typename _Type> 156 inline bool 157 __is_null_pointer(_Type) 158 { return false; } 159 160 #if __cplusplus >= 201103L 161 inline bool 162 __is_null_pointer(std::nullptr_t) 163 { return true; } 164 #endif 165 166 // For complex and cmath 167 template<typename _Tp, bool = std::__is_integer<_Tp>::__value> 168 struct __promote 169 { typedef double __type; }; 170 171 // No nested __type member for non-integer non-floating point types, 172 // allows this type to be used for SFINAE to constrain overloads in 173 // <cmath> and <complex> to only the intended types. 174 template<typename _Tp> 175 struct __promote<_Tp, false> 176 { }; 177 178 template<> 179 struct __promote<long double> 180 { typedef long double __type; }; 181 182 template<> 183 struct __promote<double> 184 { typedef double __type; }; 185 186 template<> 187 struct __promote<float> 188 { typedef float __type; }; 189 190 template<typename _Tp, typename _Up, 191 typename _Tp2 = typename __promote<_Tp>::__type, 192 typename _Up2 = typename __promote<_Up>::__type> 193 struct __promote_2 194 { 195 typedef __typeof__(_Tp2() + _Up2()) __type; 196 }; 197 198 template<typename _Tp, typename _Up, typename _Vp, 199 typename _Tp2 = typename __promote<_Tp>::__type, 200 typename _Up2 = typename __promote<_Up>::__type, 201 typename _Vp2 = typename __promote<_Vp>::__type> 202 struct __promote_3 203 { 204 typedef __typeof__(_Tp2() + _Up2() + _Vp2()) __type; 205 }; 206 207 template<typename _Tp, typename _Up, typename _Vp, typename _Wp, 208 typename _Tp2 = typename __promote<_Tp>::__type, 209 typename _Up2 = typename __promote<_Up>::__type, 210 typename _Vp2 = typename __promote<_Vp>::__type, 211 typename _Wp2 = typename __promote<_Wp>::__type> 212 struct __promote_4 213 { 214 typedef __typeof__(_Tp2() + _Up2() + _Vp2() + _Wp2()) __type; 215 }; 216 217 _GLIBCXX_END_NAMESPACE_VERSION 218 } // namespace 219 } // extern "C++" 220 221 #endif 222