libstdc++
experimental/type_traits
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1 // Variable Templates For Type Traits -*- C++ -*-
2 
3 // Copyright (C) 2014-2021 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
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
9 // any later version.
10 
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU 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 experimental/type_traits
26  * This is a TS C++ Library header.
27  *
28  * This header defines variable templates for the C++14 type traits.
29  *
30  * Equivalent variable templates are defined in namespace `std` since C++17.
31  * @see variable_templates
32  *
33  * @ingroup libfund-ts
34  * @since C++14
35  */
36 
37 //
38 // N3932 Variable Templates For Type Traits (Revision 1)
39 //
40 
41 #ifndef _GLIBCXX_EXPERIMENTAL_TYPE_TRAITS
42 #define _GLIBCXX_EXPERIMENTAL_TYPE_TRAITS 1
43 
44 #pragma GCC system_header
45 
46 #if __cplusplus >= 201402L
47 
48 #include <type_traits>
50 
51 namespace std _GLIBCXX_VISIBILITY(default)
52 {
53 _GLIBCXX_BEGIN_NAMESPACE_VERSION
54 
55 namespace experimental
56 {
57 inline namespace fundamentals_v1
58 {
59 /** @defgroup lfts_variable_templates Variable template for type traits
60  * @ingroup libfund-ts
61  * @since Library Fundamentals TS v1. C++14.
62  * @see variable_templates
63  */
64 /** @ingroup lfts_variable_templates
65  * @{
66  */
67 #define __cpp_lib_experimental_type_trait_variable_templates 201402
68 
69 // See C++14 20.10.4.1, primary type categories
70 template <typename _Tp>
71  constexpr bool is_void_v = is_void<_Tp>::value;
72 template <typename _Tp>
73  constexpr bool is_null_pointer_v = is_null_pointer<_Tp>::value;
74 template <typename _Tp>
75  constexpr bool is_integral_v = is_integral<_Tp>::value;
76 template <typename _Tp>
77  constexpr bool is_floating_point_v = is_floating_point<_Tp>::value;
78 template <typename _Tp>
79  constexpr bool is_array_v = is_array<_Tp>::value;
80 template <typename _Tp>
81  constexpr bool is_pointer_v = is_pointer<_Tp>::value;
82 template <typename _Tp>
83  constexpr bool is_lvalue_reference_v = is_lvalue_reference<_Tp>::value;
84 template <typename _Tp>
85  constexpr bool is_rvalue_reference_v = is_rvalue_reference<_Tp>::value;
86 template <typename _Tp>
87  constexpr bool is_member_object_pointer_v =
88  is_member_object_pointer<_Tp>::value;
89 template <typename _Tp>
90  constexpr bool is_member_function_pointer_v =
91  is_member_function_pointer<_Tp>::value;
92 template <typename _Tp>
93  constexpr bool is_enum_v = is_enum<_Tp>::value;
94 template <typename _Tp>
95  constexpr bool is_union_v = is_union<_Tp>::value;
96 template <typename _Tp>
97  constexpr bool is_class_v = is_class<_Tp>::value;
98 template <typename _Tp>
99  constexpr bool is_function_v = is_function<_Tp>::value;
100 
101 // See C++14 20.10.4.2, composite type categories
102 template <typename _Tp>
103  constexpr bool is_reference_v = is_reference<_Tp>::value;
104 template <typename _Tp>
105  constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
106 template <typename _Tp>
107  constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
108 template <typename _Tp>
109  constexpr bool is_object_v = is_object<_Tp>::value;
110 template <typename _Tp>
111  constexpr bool is_scalar_v = is_scalar<_Tp>::value;
112 template <typename _Tp>
113  constexpr bool is_compound_v = is_compound<_Tp>::value;
114 template <typename _Tp>
115  constexpr bool is_member_pointer_v = is_member_pointer<_Tp>::value;
116 
117 // See C++14 20.10.4.3, type properties
118 template <typename _Tp>
119  constexpr bool is_const_v = is_const<_Tp>::value;
120 template <typename _Tp>
121  constexpr bool is_volatile_v = is_volatile<_Tp>::value;
122 template <typename _Tp>
123  constexpr bool is_trivial_v = is_trivial<_Tp>::value;
124 template <typename _Tp>
125  constexpr bool is_trivially_copyable_v = is_trivially_copyable<_Tp>::value;
126 template <typename _Tp>
127  constexpr bool is_standard_layout_v = is_standard_layout<_Tp>::value;
128 #pragma GCC diagnostic push
129 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
130 template <typename _Tp>
131  constexpr bool is_pod_v = is_pod<_Tp>::value;
132 template <typename _Tp>
133  constexpr bool is_literal_type_v = is_literal_type<_Tp>::value;
134 #pragma GCC diagnostic pop
135 template <typename _Tp>
136  constexpr bool is_empty_v = is_empty<_Tp>::value;
137 template <typename _Tp>
138  constexpr bool is_polymorphic_v = is_polymorphic<_Tp>::value;
139 template <typename _Tp>
140  constexpr bool is_abstract_v = is_abstract<_Tp>::value;
141 template <typename _Tp>
142  constexpr bool is_final_v = is_final<_Tp>::value;
143 template <typename _Tp>
144  constexpr bool is_signed_v = is_signed<_Tp>::value;
145 template <typename _Tp>
146  constexpr bool is_unsigned_v = is_unsigned<_Tp>::value;
147 template <typename _Tp, typename... _Args>
148  constexpr bool is_constructible_v = is_constructible<_Tp, _Args...>::value;
149 template <typename _Tp>
150  constexpr bool is_default_constructible_v =
151  is_default_constructible<_Tp>::value;
152 template <typename _Tp>
153  constexpr bool is_copy_constructible_v = is_copy_constructible<_Tp>::value;
154 template <typename _Tp>
155  constexpr bool is_move_constructible_v = is_move_constructible<_Tp>::value;
156 template <typename _Tp, typename _Up>
157  constexpr bool is_assignable_v = is_assignable<_Tp, _Up>::value;
158 template <typename _Tp>
159  constexpr bool is_copy_assignable_v = is_copy_assignable<_Tp>::value;
160 template <typename _Tp>
161  constexpr bool is_move_assignable_v = is_move_assignable<_Tp>::value;
162 template <typename _Tp>
163  constexpr bool is_destructible_v = is_destructible<_Tp>::value;
164 template <typename _Tp, typename... _Args>
165  constexpr bool is_trivially_constructible_v =
166  is_trivially_constructible<_Tp, _Args...>::value;
167 template <typename _Tp>
168  constexpr bool is_trivially_default_constructible_v =
169  is_trivially_default_constructible<_Tp>::value;
170 template <typename _Tp>
171  constexpr bool is_trivially_copy_constructible_v =
172  is_trivially_copy_constructible<_Tp>::value;
173 template <typename _Tp>
174  constexpr bool is_trivially_move_constructible_v =
175  is_trivially_move_constructible<_Tp>::value;
176 template <typename _Tp, typename _Up>
177  constexpr bool is_trivially_assignable_v =
178  is_trivially_assignable<_Tp, _Up>::value;
179 template <typename _Tp>
180  constexpr bool is_trivially_copy_assignable_v =
181  is_trivially_copy_assignable<_Tp>::value;
182 template <typename _Tp>
183  constexpr bool is_trivially_move_assignable_v =
184  is_trivially_move_assignable<_Tp>::value;
185 template <typename _Tp>
186  constexpr bool is_trivially_destructible_v =
187  is_trivially_destructible<_Tp>::value;
188 template <typename _Tp, typename... _Args>
189  constexpr bool is_nothrow_constructible_v =
190  is_nothrow_constructible<_Tp, _Args...>::value;
191 template <typename _Tp>
192  constexpr bool is_nothrow_default_constructible_v =
193  is_nothrow_default_constructible<_Tp>::value;
194 template <typename _Tp>
195  constexpr bool is_nothrow_copy_constructible_v =
196  is_nothrow_copy_constructible<_Tp>::value;
197 template <typename _Tp>
198  constexpr bool is_nothrow_move_constructible_v =
199  is_nothrow_move_constructible<_Tp>::value;
200 template <typename _Tp, typename _Up>
201  constexpr bool is_nothrow_assignable_v =
202  is_nothrow_assignable<_Tp, _Up>::value;
203 template <typename _Tp>
204  constexpr bool is_nothrow_copy_assignable_v =
205  is_nothrow_copy_assignable<_Tp>::value;
206 template <typename _Tp>
207  constexpr bool is_nothrow_move_assignable_v =
208  is_nothrow_move_assignable<_Tp>::value;
209 template <typename _Tp>
210  constexpr bool is_nothrow_destructible_v =
211  is_nothrow_destructible<_Tp>::value;
212 template <typename _Tp>
213  constexpr bool has_virtual_destructor_v =
214  has_virtual_destructor<_Tp>::value;
215 
216 // See C++14 20.10.5, type property queries
217 template <typename _Tp>
218  constexpr size_t alignment_of_v = alignment_of<_Tp>::value;
219 template <typename _Tp>
220  constexpr size_t rank_v = rank<_Tp>::value;
221 template <typename _Tp, unsigned _Idx = 0>
222  constexpr size_t extent_v = extent<_Tp, _Idx>::value;
223 
224 // See C++14 20.10.6, type relations
225 template <typename _Tp, typename _Up>
226  constexpr bool is_same_v = is_same<_Tp, _Up>::value;
227 template <typename _Base, typename _Derived>
228  constexpr bool is_base_of_v = is_base_of<_Base, _Derived>::value;
229 template <typename _From, typename _To>
230  constexpr bool is_convertible_v = is_convertible<_From, _To>::value;
231 /// @}
232 
233  // 3.3.2, Other type transformations
234  // invocation_type (still unimplemented)
235  // raw_invocation_type (still unimplemented)
236  // invocation_type_t (still unimplemented)
237  // raw_invocation_type_t (still unimplemented)
238 } // namespace fundamentals_v1
239 
240 inline namespace fundamentals_v2
241 {
242 /**
243  * @defgroup lfts_detect Detection idiom
244  * @ingroup libfund-ts
245  * @since Library Fundamentals TS v2. C++14.
246  */
247 /** @ingroup lfts_detect
248  * @{
249  */
250 #define __cpp_lib_experimental_detect 201505
251 
252 // [meta.detect]
253 
254 /// A metafunction that always yields void, used for detecting valid types.
255 template<typename...> using void_t = void;
256 
257 #pragma GCC diagnostic push
258 #pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
259 /// @internal
260 struct __nonesuchbase {};
261 struct nonesuch : private __nonesuchbase
262 {
263  ~nonesuch() = delete;
264  nonesuch(nonesuch const&) = delete;
265  void operator=(nonesuch const&) = delete;
266 };
267 #pragma GCC diagnostic pop
268 
269 template<template<typename...> class _Op, typename... _Args>
271  = typename std::__detector<nonesuch, void, _Op, _Args...>::value_t;
272 
273 template<template<typename...> class _Op, typename... _Args>
274  constexpr bool is_detected_v = is_detected<_Op, _Args...>::value;
275 
276 template<template<typename...> class _Op, typename... _Args>
278  = typename std::__detector<nonesuch, void, _Op, _Args...>::type;
279 
280 template<typename _Default, template<typename...> class _Op, typename... _Args>
281  using detected_or = std::__detected_or<_Default, _Op, _Args...>;
282 
283 template<typename _Default, template<typename...> class _Op, typename... _Args>
284  using detected_or_t = typename detected_or<_Default, _Op, _Args...>::type;
285 
286 template<typename _Expected, template<typename...> class _Op, typename... _Args>
287  using is_detected_exact = is_same<_Expected, detected_t<_Op, _Args...>>;
288 
289 template<typename _Expected, template<typename...> class _Op, typename... _Args>
290  constexpr bool is_detected_exact_v
291  = is_detected_exact<_Expected, _Op, _Args...>::value;
292 
293 template<typename _To, template<typename...> class _Op, typename... _Args>
295  = is_convertible<detected_t<_Op, _Args...>, _To>;
296 
297 template<typename _To, template<typename...> class _Op, typename... _Args>
299  = is_detected_convertible<_To, _Op, _Args...>::value;
300 /// @}
301 
302 /**
303  * @defgroup lfts_logical Logical operator traits
304  * @ingroup libfund-ts
305  * @since Library Fundamentals TS v2. C++14.
306  */
307 /** @ingroup lfts_logical
308  * @{
309  */
310 #define __cpp_lib_experimental_logical_traits 201511
311 
312 template<typename... _Bn>
313  struct conjunction
314  : __and_<_Bn...>
315  { };
316 
317 template<typename... _Bn>
318  struct disjunction
319  : __or_<_Bn...>
320  { };
321 
322 template<typename _Pp>
323  struct negation
324  : __not_<_Pp>
325  { };
326 
327 template<typename... _Bn>
328  constexpr bool conjunction_v
329  = conjunction<_Bn...>::value;
330 
331 template<typename... _Bn>
332  constexpr bool disjunction_v
333  = disjunction<_Bn...>::value;
334 
335 template<typename _Pp>
336  constexpr bool negation_v
337  = negation<_Pp>::value;
338 /// @}
339 } // namespace fundamentals_v2
340 } // namespace experimental
341 
342 _GLIBCXX_END_NAMESPACE_VERSION
343 } // namespace std
344 
345 #endif // __cplusplus <= 201103L
346 
347 #endif // _GLIBCXX_EXPERIMENTAL_TYPE_TRAITS
constexpr bool is_detected_exact_v
A metafunction that always yields void, used for detecting valid types.
typename detected_or< _Default, _Op, _Args... >::type detected_or_t
A metafunction that always yields void, used for detecting valid types.
std::__detected_or< _Default, _Op, _Args... > detected_or
A metafunction that always yields void, used for detecting valid types.
typename std::__detector< nonesuch, void, _Op, _Args... >::value_t is_detected
A metafunction that always yields void, used for detecting valid types.
void void_t
A metafunction that always yields void, used for detecting valid types.
typename std::__detector< nonesuch, void, _Op, _Args... >::type detected_t
A metafunction that always yields void, used for detecting valid types.
constexpr bool is_detected_convertible_v
A metafunction that always yields void, used for detecting valid types.
constexpr bool is_detected_v
A metafunction that always yields void, used for detecting valid types.
ISO C++ entities toplevel namespace is std.
is_same
Definition: type_traits:1410
is_convertible
Definition: type_traits:1459