libstdc++
experimental/type_traits
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1 // Variable Templates For Type Traits -*- C++ -*-
2 
3 // Copyright (C) 2014-2025 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 #ifdef _GLIBCXX_SYSHDR
45 #pragma GCC system_header
46 #endif
47 
48 #if __cplusplus >= 201402L
49 
50 #include <type_traits>
51 #include <experimental/bits/lfts_config.h>
52 
53 namespace std _GLIBCXX_VISIBILITY(default)
54 {
55 _GLIBCXX_BEGIN_NAMESPACE_VERSION
56 
57 namespace experimental
58 {
59 inline namespace fundamentals_v1
60 {
61 /** @defgroup lfts_variable_templates Variable template for type traits
62  * @ingroup libfund-ts
63  * @since Library Fundamentals TS v1. C++14.
64  * @see variable_templates
65  */
66 /** @ingroup lfts_variable_templates
67  * @{
68  */
69 #define __cpp_lib_experimental_type_trait_variable_templates 201402
70 
71 // See C++14 20.10.4.1, primary type categories
72 template <typename _Tp>
73  constexpr bool is_void_v = is_void<_Tp>::value;
74 template <typename _Tp>
75  constexpr bool is_null_pointer_v = is_null_pointer<_Tp>::value;
76 template <typename _Tp>
77  constexpr bool is_integral_v = is_integral<_Tp>::value;
78 template <typename _Tp>
79  constexpr bool is_floating_point_v = is_floating_point<_Tp>::value;
80 template <typename _Tp>
81  constexpr bool is_array_v = is_array<_Tp>::value;
82 template <typename _Tp>
83  constexpr bool is_pointer_v = is_pointer<_Tp>::value;
84 template <typename _Tp>
85  constexpr bool is_lvalue_reference_v = is_lvalue_reference<_Tp>::value;
86 template <typename _Tp>
87  constexpr bool is_rvalue_reference_v = is_rvalue_reference<_Tp>::value;
88 template <typename _Tp>
89  constexpr bool is_member_object_pointer_v =
90  is_member_object_pointer<_Tp>::value;
91 template <typename _Tp>
92  constexpr bool is_member_function_pointer_v =
93  is_member_function_pointer<_Tp>::value;
94 template <typename _Tp>
95  constexpr bool is_enum_v = is_enum<_Tp>::value;
96 template <typename _Tp>
97  constexpr bool is_union_v = is_union<_Tp>::value;
98 template <typename _Tp>
99  constexpr bool is_class_v = is_class<_Tp>::value;
100 template <typename _Tp>
101  constexpr bool is_function_v = is_function<_Tp>::value;
102 
103 // See C++14 20.10.4.2, composite type categories
104 template <typename _Tp>
105  constexpr bool is_reference_v = is_reference<_Tp>::value;
106 template <typename _Tp>
107  constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
108 template <typename _Tp>
109  constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
110 template <typename _Tp>
111  constexpr bool is_object_v = is_object<_Tp>::value;
112 template <typename _Tp>
113  constexpr bool is_scalar_v = is_scalar<_Tp>::value;
114 template <typename _Tp>
115  constexpr bool is_compound_v = is_compound<_Tp>::value;
116 template <typename _Tp>
117  constexpr bool is_member_pointer_v = is_member_pointer<_Tp>::value;
118 
119 // See C++14 20.10.4.3, type properties
120 template <typename _Tp>
121  constexpr bool is_const_v = is_const<_Tp>::value;
122 template <typename _Tp>
123  constexpr bool is_volatile_v = is_volatile<_Tp>::value;
124 #pragma GCC diagnostic push
125 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
126 template <typename _Tp>
127  constexpr bool is_trivial_v = is_trivial<_Tp>::value;
128 #pragma GCC diagnostic pop
129 template <typename _Tp>
130  constexpr bool is_trivially_copyable_v = is_trivially_copyable<_Tp>::value;
131 template <typename _Tp>
132  constexpr bool is_standard_layout_v = is_standard_layout<_Tp>::value;
133 #pragma GCC diagnostic push
134 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
135 template <typename _Tp>
136  constexpr bool is_pod_v = is_pod<_Tp>::value;
137 template <typename _Tp>
138  constexpr bool is_literal_type_v = is_literal_type<_Tp>::value;
139 #pragma GCC diagnostic pop
140 template <typename _Tp>
141  constexpr bool is_empty_v = is_empty<_Tp>::value;
142 template <typename _Tp>
143  constexpr bool is_polymorphic_v = is_polymorphic<_Tp>::value;
144 template <typename _Tp>
145  constexpr bool is_abstract_v = is_abstract<_Tp>::value;
146 template <typename _Tp>
147  constexpr bool is_final_v = is_final<_Tp>::value;
148 template <typename _Tp>
149  constexpr bool is_signed_v = is_signed<_Tp>::value;
150 template <typename _Tp>
151  constexpr bool is_unsigned_v = is_unsigned<_Tp>::value;
152 template <typename _Tp, typename... _Args>
153  constexpr bool is_constructible_v = is_constructible<_Tp, _Args...>::value;
154 template <typename _Tp>
155  constexpr bool is_default_constructible_v =
156  is_default_constructible<_Tp>::value;
157 template <typename _Tp>
158  constexpr bool is_copy_constructible_v = is_copy_constructible<_Tp>::value;
159 template <typename _Tp>
160  constexpr bool is_move_constructible_v = is_move_constructible<_Tp>::value;
161 template <typename _Tp, typename _Up>
162  constexpr bool is_assignable_v = is_assignable<_Tp, _Up>::value;
163 template <typename _Tp>
164  constexpr bool is_copy_assignable_v = is_copy_assignable<_Tp>::value;
165 template <typename _Tp>
166  constexpr bool is_move_assignable_v = is_move_assignable<_Tp>::value;
167 template <typename _Tp>
168  constexpr bool is_destructible_v = is_destructible<_Tp>::value;
169 template <typename _Tp, typename... _Args>
170  constexpr bool is_trivially_constructible_v =
171  is_trivially_constructible<_Tp, _Args...>::value;
172 template <typename _Tp>
173  constexpr bool is_trivially_default_constructible_v =
174  is_trivially_default_constructible<_Tp>::value;
175 template <typename _Tp>
176  constexpr bool is_trivially_copy_constructible_v =
177  is_trivially_copy_constructible<_Tp>::value;
178 template <typename _Tp>
179  constexpr bool is_trivially_move_constructible_v =
180  is_trivially_move_constructible<_Tp>::value;
181 template <typename _Tp, typename _Up>
182  constexpr bool is_trivially_assignable_v =
183  is_trivially_assignable<_Tp, _Up>::value;
184 template <typename _Tp>
185  constexpr bool is_trivially_copy_assignable_v =
186  is_trivially_copy_assignable<_Tp>::value;
187 template <typename _Tp>
188  constexpr bool is_trivially_move_assignable_v =
189  is_trivially_move_assignable<_Tp>::value;
190 template <typename _Tp>
191  constexpr bool is_trivially_destructible_v =
192  is_trivially_destructible<_Tp>::value;
193 template <typename _Tp, typename... _Args>
194  constexpr bool is_nothrow_constructible_v =
195  is_nothrow_constructible<_Tp, _Args...>::value;
196 template <typename _Tp>
197  constexpr bool is_nothrow_default_constructible_v =
198  is_nothrow_default_constructible<_Tp>::value;
199 template <typename _Tp>
200  constexpr bool is_nothrow_copy_constructible_v =
201  is_nothrow_copy_constructible<_Tp>::value;
202 template <typename _Tp>
203  constexpr bool is_nothrow_move_constructible_v =
204  is_nothrow_move_constructible<_Tp>::value;
205 template <typename _Tp, typename _Up>
206  constexpr bool is_nothrow_assignable_v =
207  is_nothrow_assignable<_Tp, _Up>::value;
208 template <typename _Tp>
209  constexpr bool is_nothrow_copy_assignable_v =
210  is_nothrow_copy_assignable<_Tp>::value;
211 template <typename _Tp>
212  constexpr bool is_nothrow_move_assignable_v =
213  is_nothrow_move_assignable<_Tp>::value;
214 template <typename _Tp>
215  constexpr bool is_nothrow_destructible_v =
216  is_nothrow_destructible<_Tp>::value;
217 template <typename _Tp>
218  constexpr bool has_virtual_destructor_v =
219  has_virtual_destructor<_Tp>::value;
220 
221 // See C++14 20.10.5, type property queries
222 template <typename _Tp>
223  constexpr size_t alignment_of_v = alignment_of<_Tp>::value;
224 template <typename _Tp>
225  constexpr size_t rank_v = rank<_Tp>::value;
226 template <typename _Tp, unsigned _Idx = 0>
227  constexpr size_t extent_v = extent<_Tp, _Idx>::value;
228 
229 // See C++14 20.10.6, type relations
230 template <typename _Tp, typename _Up>
231  constexpr bool is_same_v = false;
232 template <typename _Tp>
233  constexpr bool is_same_v<_Tp, _Tp> = true;
234 template <typename _Base, typename _Derived>
235  constexpr bool is_base_of_v = is_base_of<_Base, _Derived>::value;
236 template <typename _From, typename _To>
237  constexpr bool is_convertible_v = is_convertible<_From, _To>::value;
238 /// @}
239 
240  // 3.3.2, Other type transformations
241  // invocation_type (still unimplemented)
242  // raw_invocation_type (still unimplemented)
243  // invocation_type_t (still unimplemented)
244  // raw_invocation_type_t (still unimplemented)
245 } // namespace fundamentals_v1
246 
247 inline namespace fundamentals_v2
248 {
249 /**
250  * @defgroup lfts_detect Detection idiom
251  * @ingroup libfund-ts
252  * @since Library Fundamentals TS v2. C++14.
253  */
254 /** @ingroup lfts_detect
255  * @{
256  */
257 #define __cpp_lib_experimental_detect 201505
258 
259 // [meta.detect]
260 
261 /// A metafunction that always yields void, used for detecting valid types.
262 template<typename...> using void_t = void;
263 
264 #pragma GCC diagnostic push
265 #pragma GCC diagnostic ignored "-Wctor-dtor-privacy"
266 /// @internal
267 struct __nonesuchbase {};
268 struct nonesuch : private __nonesuchbase
269 {
270  ~nonesuch() = delete;
271  nonesuch(nonesuch const&) = delete;
272  void operator=(nonesuch const&) = delete;
273 };
274 #pragma GCC diagnostic pop
275 
276 template<typename _Default, template<typename...> class _Op, typename... _Args>
277  using detected_or = std::__detected_or<_Default, _Op, _Args...>;
278 
279 template<typename _Default, template<typename...> class _Op, typename... _Args>
280  using detected_or_t = typename detected_or<_Default, _Op, _Args...>::type;
281 
282 template<template<typename...> class _Op, typename... _Args>
283  using detected_t = detected_or_t<nonesuch, _Op, _Args...>;
284 
285 template<template<typename...> class _Op, typename... _Args>
286  using is_detected = typename detected_or<void, _Op, _Args...>::__is_detected;
287 
288 template<template<typename...> class _Op, typename... _Args>
289  constexpr bool is_detected_v = is_detected<_Op, _Args...>::value;
290 
291 template<typename _Expected, template<typename...> class _Op, typename... _Args>
292  using is_detected_exact = is_same<_Expected, detected_t<_Op, _Args...>>;
293 
294 template<typename _Expected, template<typename...> class _Op, typename... _Args>
295  constexpr bool is_detected_exact_v
296  = is_detected_exact<_Expected, _Op, _Args...>::value;
297 
298 template<typename _To, template<typename...> class _Op, typename... _Args>
299  using is_detected_convertible
300  = is_convertible<detected_t<_Op, _Args...>, _To>;
301 
302 template<typename _To, template<typename...> class _Op, typename... _Args>
303  constexpr bool is_detected_convertible_v
304  = is_detected_convertible<_To, _Op, _Args...>::value;
305 /// @}
306 
307 /**
308  * @defgroup lfts_logical Logical operator traits
309  * @ingroup libfund-ts
310  * @since Library Fundamentals TS v2. C++14.
311  */
312 /** @ingroup lfts_logical
313  * @{
314  */
315 #define __cpp_lib_experimental_logical_traits 201511
316 
317 template<typename... _Bn>
318  struct conjunction
319  : __and_<_Bn...>
320  { };
321 
322 template<typename... _Bn>
323  struct disjunction
324  : __or_<_Bn...>
325  { };
326 
327 template<typename _Pp>
328  struct negation
329  : __not_<_Pp>
330  { };
331 
332 template<typename... _Bn>
333  constexpr bool conjunction_v
334  = conjunction<_Bn...>::value;
335 
336 template<typename... _Bn>
337  constexpr bool disjunction_v
338  = disjunction<_Bn...>::value;
339 
340 template<typename _Pp>
341  constexpr bool negation_v
342  = negation<_Pp>::value;
343 /// @}
344 } // namespace fundamentals_v2
345 } // namespace experimental
346 
347 _GLIBCXX_END_NAMESPACE_VERSION
348 } // namespace std
349 
350 #endif // __cplusplus <= 201103L
351 
352 #endif // _GLIBCXX_EXPERIMENTAL_TYPE_TRAITS