3 // Copyright (C) 2005, 2006, 2007, 2009 Free Software Foundation, Inc.
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
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.
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.
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/>.
25 /** @file ext/type_traits.h
26 * This file is a GNU extension to the Standard C++ Library.
29 #ifndef _EXT_TYPE_TRAITS
30 #define _EXT_TYPE_TRAITS 1
32 #pragma GCC system_header
34 #include <bits/c++config.h>
35 #include <bits/cpp_type_traits.h>
37 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
39 // Define a nested type if some predicate holds.
40 template<bool, typename>
44 template<typename _Tp>
45 struct __enable_if<true, _Tp>
46 { typedef _Tp __type; };
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; };
54 template<typename _Iftrue, typename _Iffalse>
55 struct __conditional_type<false, _Iftrue, _Iffalse>
56 { typedef _Iffalse __type; };
59 // Given an integral builtin type, return the corresponding unsigned type.
60 template<typename _Tp>
64 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
67 typedef typename __if_type::__type __type;
71 struct __add_unsigned<char>
72 { typedef unsigned char __type; };
75 struct __add_unsigned<signed char>
76 { typedef unsigned char __type; };
79 struct __add_unsigned<short>
80 { typedef unsigned short __type; };
83 struct __add_unsigned<int>
84 { typedef unsigned int __type; };
87 struct __add_unsigned<long>
88 { typedef unsigned long __type; };
91 struct __add_unsigned<long long>
92 { typedef unsigned long long __type; };
94 // Declare but don't define.
96 struct __add_unsigned<bool>;
99 struct __add_unsigned<wchar_t>;
102 // Given an integral builtin type, return the corresponding signed type.
103 template<typename _Tp>
104 struct __remove_unsigned
107 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
110 typedef typename __if_type::__type __type;
114 struct __remove_unsigned<char>
115 { typedef signed char __type; };
118 struct __remove_unsigned<unsigned char>
119 { typedef signed char __type; };
122 struct __remove_unsigned<unsigned short>
123 { typedef short __type; };
126 struct __remove_unsigned<unsigned int>
127 { typedef int __type; };
130 struct __remove_unsigned<unsigned long>
131 { typedef long __type; };
134 struct __remove_unsigned<unsigned long long>
135 { typedef long long __type; };
137 // Declare but don't define.
139 struct __remove_unsigned<bool>;
142 struct __remove_unsigned<wchar_t>;
145 // For use in string and vstring.
146 template<typename _Type>
148 __is_null_pointer(_Type* __ptr)
149 { return __ptr == 0; }
151 template<typename _Type>
153 __is_null_pointer(_Type)
157 // For complex and cmath
158 template<typename _Tp, bool = std::__is_integer<_Tp>::__value>
160 { typedef double __type; };
162 template<typename _Tp>
163 struct __promote<_Tp, false>
164 { typedef _Tp __type; };
166 template<typename _Tp, typename _Up>
170 typedef typename __promote<_Tp>::__type __type1;
171 typedef typename __promote<_Up>::__type __type2;
174 typedef __typeof__(__type1() + __type2()) __type;
177 template<typename _Tp, typename _Up, typename _Vp>
181 typedef typename __promote<_Tp>::__type __type1;
182 typedef typename __promote<_Up>::__type __type2;
183 typedef typename __promote<_Vp>::__type __type3;
186 typedef __typeof__(__type1() + __type2() + __type3()) __type;
189 template<typename _Tp, typename _Up, typename _Vp, typename _Wp>
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;
199 typedef __typeof__(__type1() + __type2() + __type3() + __type4()) __type;
202 _GLIBCXX_END_NAMESPACE