1// -*- C++ -*- 2 3// Copyright (C) 2005, 2006, 2007, 2009 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_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx) 38 39 // Define a nested type if some predicate holds. 40 template<bool, typename> 41 struct __enable_if 42 { }; 43 44 template<typename _Tp> 45 struct __enable_if<true, _Tp> 46 { typedef _Tp __type; }; 47 48 49 // Conditional expression for types. If true, first, if false, second. 50 template<bool _Cond, typename _Iftrue, typename _Iffalse> 51 struct __conditional_type 52 { typedef _Iftrue __type; }; 53 54 template<typename _Iftrue, typename _Iffalse> 55 struct __conditional_type<false, _Iftrue, _Iffalse> 56 { typedef _Iffalse __type; }; 57 58 59 // Given an integral builtin type, return the corresponding unsigned type. 60 template<typename _Tp> 61 struct __add_unsigned 62 { 63 private: 64 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 65 66 public: 67 typedef typename __if_type::__type __type; 68 }; 69 70 template<> 71 struct __add_unsigned<char> 72 { typedef unsigned char __type; }; 73 74 template<> 75 struct __add_unsigned<signed char> 76 { typedef unsigned char __type; }; 77 78 template<> 79 struct __add_unsigned<short> 80 { typedef unsigned short __type; }; 81 82 template<> 83 struct __add_unsigned<int> 84 { typedef unsigned int __type; }; 85 86 template<> 87 struct __add_unsigned<long> 88 { typedef unsigned long __type; }; 89 90 template<> 91 struct __add_unsigned<long long> 92 { typedef unsigned long long __type; }; 93 94 // Declare but don't define. 95 template<> 96 struct __add_unsigned<bool>; 97 98 template<> 99 struct __add_unsigned<wchar_t>; 100 101 102 // Given an integral builtin type, return the corresponding signed type. 103 template<typename _Tp> 104 struct __remove_unsigned 105 { 106 private: 107 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type; 108 109 public: 110 typedef typename __if_type::__type __type; 111 }; 112 113 template<> 114 struct __remove_unsigned<char> 115 { typedef signed char __type; }; 116 117 template<> 118 struct __remove_unsigned<unsigned char> 119 { typedef signed char __type; }; 120 121 template<> 122 struct __remove_unsigned<unsigned short> 123 { typedef short __type; }; 124 125 template<> 126 struct __remove_unsigned<unsigned int> 127 { typedef int __type; }; 128 129 template<> 130 struct __remove_unsigned<unsigned long> 131 { typedef long __type; }; 132 133 template<> 134 struct __remove_unsigned<unsigned long long> 135 { typedef long long __type; }; 136 137 // Declare but don't define. 138 template<> 139 struct __remove_unsigned<bool>; 140 141 template<> 142 struct __remove_unsigned<wchar_t>; 143 144 145 // For use in string and vstring. 146 template<typename _Type> 147 inline bool 148 __is_null_pointer(_Type* __ptr) 149 { return __ptr == 0; } 150 151 template<typename _Type> 152 inline bool 153 __is_null_pointer(_Type) 154 { return false; } 155 156 157 // For complex and cmath 158 template<typename _Tp, bool = std::__is_integer<_Tp>::__value> 159 struct __promote 160 { typedef double __type; }; 161 162 template<typename _Tp> 163 struct __promote<_Tp, false> 164 { typedef _Tp __type; }; 165 166 template<typename _Tp, typename _Up> 167 struct __promote_2 168 { 169 private: 170 typedef typename __promote<_Tp>::__type __type1; 171 typedef typename __promote<_Up>::__type __type2; 172 173 public: 174 typedef __typeof__(__type1() + __type2()) __type; 175 }; 176 177 template<typename _Tp, typename _Up, typename _Vp> 178 struct __promote_3 179 { 180 private: 181 typedef typename __promote<_Tp>::__type __type1; 182 typedef typename __promote<_Up>::__type __type2; 183 typedef typename __promote<_Vp>::__type __type3; 184 185 public: 186 typedef __typeof__(__type1() + __type2() + __type3()) __type; 187 }; 188 189 template<typename _Tp, typename _Up, typename _Vp, typename _Wp> 190 struct __promote_4 191 { 192 private: 193 typedef typename __promote<_Tp>::__type __type1; 194 typedef typename __promote<_Up>::__type __type2; 195 typedef typename __promote<_Vp>::__type __type3; 196 typedef typename __promote<_Wp>::__type __type4; 197 198 public: 199 typedef __typeof__(__type1() + __type2() + __type3() + __type4()) __type; 200 }; 201 202_GLIBCXX_END_NAMESPACE 203 204#endif 205