1 // -*- C++ -*- 2 3 // Copyright (C) 2005, 2006, 2007, 2009, 2010, 2011 4 // Free Software Foundation, Inc. 5 // 6 // This file is part of the GNU ISO C++ Library. This library is free 7 // software; you can redistribute it and/or modify it under the terms 8 // of the GNU General Public License as published by the Free Software 9 // Foundation; either version 3, or (at your option) any later 10 // version. 11 12 // This library is distributed in the hope that it will be useful, but 13 // WITHOUT ANY WARRANTY; without even the implied warranty of 14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 // General Public License for more details. 16 17 // Under Section 7 of GPL version 3, you are granted additional 18 // permissions described in the GCC Runtime Library Exception, version 19 // 3.1, as published by the Free Software Foundation. 20 21 // You should have received a copy of the GNU General Public License and 22 // a copy of the GCC Runtime Library Exception along with this program; 23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 // <http://www.gnu.org/licenses/>. 25 26 /** @file ext/type_traits.h 27 * This file is a GNU extension to the Standard C++ Library. 28 */ 29 30 #ifndef _EXT_TYPE_TRAITS 31 #define _EXT_TYPE_TRAITS 1 32 33 #pragma GCC system_header 34 35 #include <bits/c++config.h> 36 #include <bits/cpp_type_traits.h> 37 38 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 39 { 40 _GLIBCXX_BEGIN_NAMESPACE_VERSION 41 42 // Define a nested type if some predicate holds. 43 template<bool, typename> 44 struct __enable_if 45 { }; 46 47 template<typename _Tp> 48 struct __enable_if<true, _Tp> 49 { typedef _Tp __type; }; 50 51 52 // Conditional expression for types. If true, first, if false, second. 53 template<bool _Cond, typename _Iftrue, typename _Iffalse> 54 struct __conditional_type 55 { typedef _Iftrue __type; }; 56 57 template<typename _Iftrue, typename _Iffalse> 58 struct __conditional_type<false, _Iftrue, _Iffalse> 59 { typedef _Iffalse __type; }; 60 61 62 // Given an integral builtin type, return the corresponding unsigned type. 63 template<typename _Tp> 64 struct __add_unsigned 65 { 66 private: 67 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 68 69 public: 70 typedef typename __if_type::__type __type; 71 }; 72 73 template<> 74 struct __add_unsigned<char> 75 { typedef unsigned char __type; }; 76 77 template<> 78 struct __add_unsigned<signed char> 79 { typedef unsigned char __type; }; 80 81 template<> 82 struct __add_unsigned<short> 83 { typedef unsigned short __type; }; 84 85 template<> 86 struct __add_unsigned<int> 87 { typedef unsigned int __type; }; 88 89 template<> 90 struct __add_unsigned<long> 91 { typedef unsigned long __type; }; 92 93 template<> 94 struct __add_unsigned<long long> 95 { typedef unsigned long long __type; }; 96 97 // Declare but don't define. 98 template<> 99 struct __add_unsigned<bool>; 100 101 template<> 102 struct __add_unsigned<wchar_t>; 103 104 105 // Given an integral builtin type, return the corresponding signed type. 106 template<typename _Tp> 107 struct __remove_unsigned 108 { 109 private: 110 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 111 112 public: 113 typedef typename __if_type::__type __type; 114 }; 115 116 template<> 117 struct __remove_unsigned<char> 118 { typedef signed char __type; }; 119 120 template<> 121 struct __remove_unsigned<unsigned char> 122 { typedef signed char __type; }; 123 124 template<> 125 struct __remove_unsigned<unsigned short> 126 { typedef short __type; }; 127 128 template<> 129 struct __remove_unsigned<unsigned int> 130 { typedef int __type; }; 131 132 template<> 133 struct __remove_unsigned<unsigned long> 134 { typedef long __type; }; 135 136 template<> 137 struct __remove_unsigned<unsigned long long> 138 { typedef long long __type; }; 139 140 // Declare but don't define. 141 template<> 142 struct __remove_unsigned<bool>; 143 144 template<> 145 struct __remove_unsigned<wchar_t>; 146 147 148 // For use in string and vstring. 149 template<typename _Type> 150 inline bool 151 __is_null_pointer(_Type* __ptr) 152 { return __ptr == 0; } 153 154 template<typename _Type> 155 inline bool 156 __is_null_pointer(_Type) 157 { return false; } 158 159 160 // For complex and cmath 161 template<typename _Tp, bool = std::__is_integer<_Tp>::__value> 162 struct __promote 163 { typedef double __type; }; 164 165 // No nested __type member for non-integer non-floating point types, 166 // allows this type to be used for SFINAE to constrain overloads in 167 // <cmath> and <complex> to only the intended types. 168 template<typename _Tp> 169 struct __promote<_Tp, false> 170 { }; 171 172 template<> 173 struct __promote<long double> 174 { typedef long double __type; }; 175 176 template<> 177 struct __promote<double> 178 { typedef double __type; }; 179 180 template<> 181 struct __promote<float> 182 { typedef float __type; }; 183 184 template<typename _Tp, typename _Up, 185 typename _Tp2 = typename __promote<_Tp>::__type, 186 typename _Up2 = typename __promote<_Up>::__type> 187 struct __promote_2 188 { 189 typedef __typeof__(_Tp2() + _Up2()) __type; 190 }; 191 192 template<typename _Tp, typename _Up, typename _Vp, 193 typename _Tp2 = typename __promote<_Tp>::__type, 194 typename _Up2 = typename __promote<_Up>::__type, 195 typename _Vp2 = typename __promote<_Vp>::__type> 196 struct __promote_3 197 { 198 typedef __typeof__(_Tp2() + _Up2() + _Vp2()) __type; 199 }; 200 201 template<typename _Tp, typename _Up, typename _Vp, typename _Wp, 202 typename _Tp2 = typename __promote<_Tp>::__type, 203 typename _Up2 = typename __promote<_Up>::__type, 204 typename _Vp2 = typename __promote<_Vp>::__type, 205 typename _Wp2 = typename __promote<_Wp>::__type> 206 struct __promote_4 207 { 208 typedef __typeof__(_Tp2() + _Up2() + _Vp2() + _Wp2()) __type; 209 }; 210 211 _GLIBCXX_END_NAMESPACE_VERSION 212 } // namespace 213 214 #endif 215
