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
42 #include <bits/cpp_type_traits.h>
44 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
46 // Define a nested type if some predicate holds.
47 template<bool, typename>
51 template<typename _Tp>
52 struct __enable_if<true, _Tp>
53 { typedef _Tp __type; };
56 // Conditional expression for types. If true, first, if false, second.
57 template<bool _Cond, typename _Iftrue, typename _Iffalse>
58 struct __conditional_type
59 { typedef _Iftrue __type; };
61 template<typename _Iftrue, typename _Iffalse>
62 struct __conditional_type<false, _Iftrue, _Iffalse>
63 { typedef _Iffalse __type; };
66 // Given an integral builtin type, return the corresponding unsigned type.
67 template<typename _Tp>
71 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
74 typedef typename __if_type::__type __type;
78 struct __add_unsigned<char>
79 { typedef unsigned char __type; };
82 struct __add_unsigned<signed char>
83 { typedef unsigned char __type; };
86 struct __add_unsigned<short>
87 { typedef unsigned short __type; };
90 struct __add_unsigned<int>
91 { typedef unsigned int __type; };
94 struct __add_unsigned<long>
95 { typedef unsigned long __type; };
98 struct __add_unsigned<long long>
99 { typedef unsigned long long __type; };
101 // Declare but don't define.
103 struct __add_unsigned<bool>;
106 struct __add_unsigned<wchar_t>;
109 // Given an integral builtin type, return the corresponding signed type.
110 template<typename _Tp>
111 struct __remove_unsigned
114 typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
117 typedef typename __if_type::__type __type;
121 struct __remove_unsigned<char>
122 { typedef signed char __type; };
125 struct __remove_unsigned<unsigned char>
126 { typedef signed char __type; };
129 struct __remove_unsigned<unsigned short>
130 { typedef short __type; };
133 struct __remove_unsigned<unsigned int>
134 { typedef int __type; };
137 struct __remove_unsigned<unsigned long>
138 { typedef long __type; };
141 struct __remove_unsigned<unsigned long long>
142 { typedef long long __type; };
144 // Declare but don't define.
146 struct __remove_unsigned<bool>;
149 struct __remove_unsigned<wchar_t>;
151 _GLIBCXX_END_NAMESPACE