1 // -*- C++ -*- 2 3 // Copyright (C) 2005-2013 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 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 38 { 39 _GLIBCXX_BEGIN_NAMESPACE_VERSION 40 41 // Define a nested type if some predicate holds. 42 template<bool, typename> 43 struct __enable_if 44 { }; 45 46 template<typename _Tp> 47 struct __enable_if<true, _Tp> 48 { typedef _Tp __type; }; 49 50 51 // Conditional expression for types. If true, first, if false, second. 52 template<bool _Cond, typename _Iftrue, typename _Iffalse> 53 struct __conditional_type 54 { typedef _Iftrue __type; }; 55 56 template<typename _Iftrue, typename _Iffalse> 57 struct __conditional_type<false, _Iftrue, _Iffalse> 58 { typedef _Iffalse __type; }; 59 60 61 // Given an integral builtin type, return the corresponding unsigned type. 62 template<typename _Tp> 63 struct __add_unsigned 64 { 65 private: 66 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 67 68 public: 69 typedef typename __if_type::__type __type; 70 }; 71 72 template<> 73 struct __add_unsigned<char> 74 { typedef unsigned char __type; }; 75 76 template<> 77 struct __add_unsigned<signed char> 78 { typedef unsigned char __type; }; 79 80 template<> 81 struct __add_unsigned<short> 82 { typedef unsigned short __type; }; 83 84 template<> 85 struct __add_unsigned<int> 86 { typedef unsigned int __type; }; 87 88 template<> 89 struct __add_unsigned<long> 90 { typedef unsigned long __type; }; 91 92 template<> 93 struct __add_unsigned<long long> 94 { typedef unsigned long long __type; }; 95 96 // Declare but don't define. 97 template<> 98 struct __add_unsigned<bool>; 99 100 template<> 101 struct __add_unsigned<wchar_t>; 102 103 104 // Given an integral builtin type, return the corresponding signed type. 105 template<typename _Tp> 106 struct __remove_unsigned 107 { 108 private: 109 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 110 111 public: 112 typedef typename __if_type::__type __type; 113 }; 114 115 template<> 116 struct __remove_unsigned<char> 117 { typedef signed char __type; }; 118 119 template<> 120 struct __remove_unsigned<unsigned char> 121 { typedef signed char __type; }; 122 123 template<> 124 struct __remove_unsigned<unsigned short> 125 { typedef short __type; }; 126 127 template<> 128 struct __remove_unsigned<unsigned int> 129 { typedef int __type; }; 130 131 template<> 132 struct __remove_unsigned<unsigned long> 133 { typedef long __type; }; 134 135 template<> 136 struct __remove_unsigned<unsigned long long> 137 { typedef long long __type; }; 138 139 // Declare but don't define. 140 template<> 141 struct __remove_unsigned<bool>; 142 143 template<> 144 struct __remove_unsigned<wchar_t>; 145 146 147 // For use in string and vstring. 148 template<typename _Type> 149 inline bool 150 __is_null_pointer(_Type* __ptr) 151 { return __ptr == 0; } 152 153 template<typename _Type> 154 inline bool 155 __is_null_pointer(_Type) 156 { return false; } 157 158 159 // For complex and cmath 160 template<typename _Tp, bool = std::__is_integer<_Tp>::__value> 161 struct __promote 162 { typedef double __type; }; 163 164 // No nested __type member for non-integer non-floating point types, 165 // allows this type to be used for SFINAE to constrain overloads in 166 // <cmath> and <complex> to only the intended types. 167 template<typename _Tp> 168 struct __promote<_Tp, false> 169 { }; 170 171 template<> 172 struct __promote<long double> 173 { typedef long double __type; }; 174 175 template<> 176 struct __promote<double> 177 { typedef double __type; }; 178 179 template<> 180 struct __promote<float> 181 { typedef float __type; }; 182 183 template<typename _Tp, typename _Up, 184 typename _Tp2 = typename __promote<_Tp>::__type, 185 typename _Up2 = typename __promote<_Up>::__type> 186 struct __promote_2 187 { 188 typedef __typeof__(_Tp2() + _Up2()) __type; 189 }; 190 191 template<typename _Tp, typename _Up, typename _Vp, 192 typename _Tp2 = typename __promote<_Tp>::__type, 193 typename _Up2 = typename __promote<_Up>::__type, 194 typename _Vp2 = typename __promote<_Vp>::__type> 195 struct __promote_3 196 { 197 typedef __typeof__(_Tp2() + _Up2() + _Vp2()) __type; 198 }; 199 200 template<typename _Tp, typename _Up, typename _Vp, typename _Wp, 201 typename _Tp2 = typename __promote<_Tp>::__type, 202 typename _Up2 = typename __promote<_Up>::__type, 203 typename _Vp2 = typename __promote<_Vp>::__type, 204 typename _Wp2 = typename __promote<_Wp>::__type> 205 struct __promote_4 206 { 207 typedef __typeof__(_Tp2() + _Up2() + _Vp2() + _Wp2()) __type; 208 }; 209 210 _GLIBCXX_END_NAMESPACE_VERSION 211 } // namespace 212 213 #endif 214
