3 // Copyright (C) 2005, 2006, 2007 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 2, 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 // You should have received a copy of the GNU General Public License along
17 // with this library; see the file COPYING. If not, write to the Free
18 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
21 // As a special exception, you may use this file as part of a free
22 // software library without restriction. Specifically, if other files
23 // instantiate templates or use macros or inline functions from this
24 // file, or you compile this file and link it with other files to
25 // produce an executable, this file does not by itself cause the
26 // resulting executable to be covered by the GNU General Public
27 // License. This exception does not however invalidate any other
28 // reasons why the executable file might be covered by the GNU General
31 /** @file ext/type_traits.h
32 * This file is a GNU extension to the Standard C++ Library.
35 #ifndef _EXT_TYPE_TRAITS
36 #define _EXT_TYPE_TRAITS 1
38 #pragma GCC system_header
40 #include <bits/c++config.h>
41 #include <bits/cpp_type_traits.h>
43 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
45 // Define a nested type if some predicate holds.
46 template<bool, typename>
50 template<typename _Tp>
51 struct __enable_if<true, _Tp>
52 { typedef _Tp __type; };
55 // Conditional expression for types. If true, first, if false, second.
56 template<bool _Cond, typename _Iftrue, typename _Iffalse>
57 struct __conditional_type
58 { typedef _Iftrue __type; };
60 template<typename _Iftrue, typename _Iffalse>
61 struct __conditional_type<false, _Iftrue, _Iffalse>
62 { typedef _Iffalse __type; };
65 // Given an integral builtin type, return the corresponding unsigned type.
66 template<typename _Tp>
70 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
73 typedef typename __if_type::__type __type;
77 struct __add_unsigned<char>
78 { typedef unsigned char __type; };
81 struct __add_unsigned<signed char>
82 { typedef unsigned char __type; };
85 struct __add_unsigned<short>
86 { typedef unsigned short __type; };
89 struct __add_unsigned<int>
90 { typedef unsigned int __type; };
93 struct __add_unsigned<long>
94 { typedef unsigned long __type; };
97 struct __add_unsigned<long long>
98 { typedef unsigned long long __type; };
100 // Declare but don't define.
102 struct __add_unsigned<bool>;
105 struct __add_unsigned<wchar_t>;
108 // Given an integral builtin type, return the corresponding signed type.
109 template<typename _Tp>
110 struct __remove_unsigned
113 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
116 typedef typename __if_type::__type __type;
120 struct __remove_unsigned<char>
121 { typedef signed char __type; };
124 struct __remove_unsigned<unsigned char>
125 { typedef signed char __type; };
128 struct __remove_unsigned<unsigned short>
129 { typedef short __type; };
132 struct __remove_unsigned<unsigned int>
133 { typedef int __type; };
136 struct __remove_unsigned<unsigned long>
137 { typedef long __type; };
140 struct __remove_unsigned<unsigned long long>
141 { typedef long long __type; };
143 // Declare but don't define.
145 struct __remove_unsigned<bool>;
148 struct __remove_unsigned<wchar_t>;
151 // For use in string and vstring.
152 template<typename _Type>
154 __is_null_pointer(_Type* __ptr)
155 { return __ptr == 0; }
157 template<typename _Type>
159 __is_null_pointer(_Type)
163 // For complex and cmath
164 template<typename _Tp, bool = std::__is_integer<_Tp>::__value>
166 { typedef double __type; };
168 template<typename _Tp>
169 struct __promote<_Tp, false>
170 { typedef _Tp __type; };
172 template<typename _Tp, typename _Up>
176 typedef typename __promote<_Tp>::__type __type1;
177 typedef typename __promote<_Up>::__type __type2;
180 typedef __typeof__(__type1() + __type2()) __type;
183 template<typename _Tp, typename _Up, typename _Vp>
187 typedef typename __promote<_Tp>::__type __type1;
188 typedef typename __promote<_Up>::__type __type2;
189 typedef typename __promote<_Vp>::__type __type3;
192 typedef __typeof__(__type1() + __type2() + __type3()) __type;
195 template<typename _Tp, typename _Up, typename _Vp, typename _Wp>
199 typedef typename __promote<_Tp>::__type __type1;
200 typedef typename __promote<_Up>::__type __type2;
201 typedef typename __promote<_Vp>::__type __type3;
202 typedef typename __promote<_Wp>::__type __type4;
205 typedef __typeof__(__type1() + __type2() + __type3() + __type4()) __type;
208 _GLIBCXX_END_NAMESPACE