3 // Copyright (C) 2005-2019 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>
39 namespace __gnu_cxx
_GLIBCXX_VISIBILITY(default)
41 _GLIBCXX_BEGIN_NAMESPACE_VERSION
43 // Define a nested type if some predicate holds.
44 template<bool, typename
>
48 template<typename _Tp
>
49 struct __enable_if
<true, _Tp
>
50 { typedef _Tp __type
; };
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
; };
58 template<typename _Iftrue
, typename _Iffalse
>
59 struct __conditional_type
<false, _Iftrue
, _Iffalse
>
60 { typedef _Iffalse __type
; };
63 // Given an integral builtin type, return the corresponding unsigned type.
64 template<typename _Tp
>
68 typedef __enable_if
<std::__is_integer
<_Tp
>::__value
, _Tp
> __if_type
;
71 typedef typename
__if_type::__type __type
;
75 struct __add_unsigned
<char>
76 { typedef unsigned char __type
; };
79 struct __add_unsigned
<signed char>
80 { typedef unsigned char __type
; };
83 struct __add_unsigned
<short>
84 { typedef unsigned short __type
; };
87 struct __add_unsigned
<int>
88 { typedef unsigned int __type
; };
91 struct __add_unsigned
<long>
92 { typedef unsigned long __type
; };
95 struct __add_unsigned
<long long>
96 { typedef unsigned long long __type
; };
98 // Declare but don't define.
100 struct __add_unsigned
<bool>;
103 struct __add_unsigned
<wchar_t>;
106 // Given an integral builtin type, return the corresponding signed type.
107 template<typename _Tp
>
108 struct __remove_unsigned
111 typedef __enable_if
<std::__is_integer
<_Tp
>::__value
, _Tp
> __if_type
;
114 typedef typename
__if_type::__type __type
;
118 struct __remove_unsigned
<char>
119 { typedef signed char __type
; };
122 struct __remove_unsigned
<unsigned char>
123 { typedef signed char __type
; };
126 struct __remove_unsigned
<unsigned short>
127 { typedef short __type
; };
130 struct __remove_unsigned
<unsigned int>
131 { typedef int __type
; };
134 struct __remove_unsigned
<unsigned long>
135 { typedef long __type
; };
138 struct __remove_unsigned
<unsigned long long>
139 { typedef long long __type
; };
141 // Declare but don't define.
143 struct __remove_unsigned
<bool>;
146 struct __remove_unsigned
<wchar_t>;
149 // For use in string and vstring.
150 template<typename _Type
>
152 __is_null_pointer(_Type
* __ptr
)
153 { return __ptr
== 0; }
155 template<typename _Type
>
157 __is_null_pointer(_Type
)
160 #if __cplusplus >= 201103L
162 __is_null_pointer(std::nullptr_t
)
166 // For complex and cmath
167 template<typename _Tp
, bool = std::__is_integer
<_Tp
>::__value
>
169 { typedef double __type
; };
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>
179 struct __promote
<long double>
180 { typedef long double __type
; };
183 struct __promote
<double>
184 { typedef double __type
; };
187 struct __promote
<float>
188 { typedef float __type
; };
190 template<typename _Tp
, typename _Up
,
191 typename _Tp2
= typename __promote
<_Tp
>::__type
,
192 typename _Up2
= typename __promote
<_Up
>::__type
>
195 typedef __typeof__(_Tp2() + _Up2()) __type
;
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
>
204 typedef __typeof__(_Tp2() + _Up2() + _Vp2()) __type
;
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
>
214 typedef __typeof__(_Tp2() + _Up2() + _Vp2() + _Wp2()) __type
;
217 _GLIBCXX_END_NAMESPACE_VERSION