1// -*- C++ -*-
2
3// Copyright (C) 2005-2015 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
37namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
38{
39_GLIBCXX_BEGIN_NAMESPACE_VERSION
40
41  // Define a nested type if some predicate holds.
42  template<bool, typename>
43    struct __enable_if
44    { };
45
46  template<typename _Tp>
47    struct __enable_if<true, _Tp>
48    { typedef _Tp __type; };
49
50
51  // Conditional expression for types. If true, first, if false, second.
52  template<bool _Cond, typename _Iftrue, typename _Iffalse>
53    struct __conditional_type
54    { typedef _Iftrue __type; };
55
56  template<typename _Iftrue, typename _Iffalse>
57    struct __conditional_type<false, _Iftrue, _Iffalse>
58    { typedef _Iffalse __type; };
59
60
61  // Given an integral builtin type, return the corresponding unsigned type.
62  template<typename _Tp>
63    struct __add_unsigned
64    {
65    private:
66      typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
67
68    public:
69      typedef typename __if_type::__type __type;
70    };
71
72  template<>
73    struct __add_unsigned<char>
74    { typedef unsigned char __type; };
75
76  template<>
77    struct __add_unsigned<signed char>
78    { typedef unsigned char __type; };
79
80  template<>
81    struct __add_unsigned<short>
82    { typedef unsigned short __type; };
83
84  template<>
85    struct __add_unsigned<int>
86    { typedef unsigned int __type; };
87
88  template<>
89    struct __add_unsigned<long>
90    { typedef unsigned long __type; };
91
92  template<>
93    struct __add_unsigned<long long>
94    { typedef unsigned long long __type; };
95
96  // Declare but don't define.
97  template<>
98    struct __add_unsigned<bool>;
99
100  template<>
101    struct __add_unsigned<wchar_t>;
102
103
104  // Given an integral builtin type, return the corresponding signed type.
105  template<typename _Tp>
106    struct __remove_unsigned
107    {
108    private:
109      typedef __enable_if<std::__is_integer<_Tp>::__value, _Tp> __if_type;
110
111    public:
112      typedef typename __if_type::__type __type;
113    };
114
115  template<>
116    struct __remove_unsigned<char>
117    { typedef signed char __type; };
118
119  template<>
120    struct __remove_unsigned<unsigned char>
121    { typedef signed char __type; };
122
123  template<>
124    struct __remove_unsigned<unsigned short>
125    { typedef short __type; };
126
127  template<>
128    struct __remove_unsigned<unsigned int>
129    { typedef int __type; };
130
131  template<>
132    struct __remove_unsigned<unsigned long>
133    { typedef long __type; };
134
135  template<>
136    struct __remove_unsigned<unsigned long long>
137    { typedef long long __type; };
138
139  // Declare but don't define.
140  template<>
141    struct __remove_unsigned<bool>;
142
143  template<>
144    struct __remove_unsigned<wchar_t>;
145
146
147  // For use in string and vstring.
148  template<typename _Type>
149    inline bool
150    __is_null_pointer(_Type* __ptr)
151    { return __ptr == 0; }
152
153  template<typename _Type>
154    inline bool
155    __is_null_pointer(_Type)
156    { return false; }
157
158#if __cplusplus >= 201103L
159  inline bool
160  __is_null_pointer(std::nullptr_t)
161  { return true; }
162#endif
163
164  // For complex and cmath
165  template<typename _Tp, bool = std::__is_integer<_Tp>::__value>
166    struct __promote
167    { typedef double __type; };
168
169  // No nested __type member for non-integer non-floating point types,
170  // allows this type to be used for SFINAE to constrain overloads in
171  // <cmath> and <complex> to only the intended types.
172  template<typename _Tp>
173    struct __promote<_Tp, false>
174    { };
175
176  template<>
177    struct __promote<long double>
178    { typedef long double __type; };
179
180  template<>
181    struct __promote<double>
182    { typedef double __type; };
183
184  template<>
185    struct __promote<float>
186    { typedef float __type; };
187
188  template<typename _Tp, typename _Up,
189           typename _Tp2 = typename __promote<_Tp>::__type,
190           typename _Up2 = typename __promote<_Up>::__type>
191    struct __promote_2
192    {
193      typedef __typeof__(_Tp2() + _Up2()) __type;
194    };
195
196  template<typename _Tp, typename _Up, typename _Vp,
197           typename _Tp2 = typename __promote<_Tp>::__type,
198           typename _Up2 = typename __promote<_Up>::__type,
199           typename _Vp2 = typename __promote<_Vp>::__type>
200    struct __promote_3
201    {
202      typedef __typeof__(_Tp2() + _Up2() + _Vp2()) __type;
203    };
204
205  template<typename _Tp, typename _Up, typename _Vp, typename _Wp,
206           typename _Tp2 = typename __promote<_Tp>::__type,
207           typename _Up2 = typename __promote<_Up>::__type,
208           typename _Vp2 = typename __promote<_Vp>::__type,
209           typename _Wp2 = typename __promote<_Wp>::__type>
210    struct __promote_4
211    {
212      typedef __typeof__(_Tp2() + _Up2() + _Vp2() + _Wp2()) __type;
213    };
214
215_GLIBCXX_END_NAMESPACE_VERSION
216} // namespace
217
218#endif
219