libstdc++: type_traits Source File

libstdc++

experimental/type_traits
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1// Variable Templates For Type Traits -*- C++ -*-
2
3// Copyright (C) 2014-2026 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
53namespace std _GLIBCXX_VISIBILITY(default)
54{
55_GLIBCXX_BEGIN_NAMESPACE_VERSION
56
57namespace experimental
58{
59inline 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
72template <typename _Tp>
73 constexpr bool is_void_v = is_void<_Tp>::value;
74template <typename _Tp>
75 constexpr bool is_null_pointer_v = is_null_pointer<_Tp>::value;
76template <typename _Tp>
77 constexpr bool is_integral_v = is_integral<_Tp>::value;
78template <typename _Tp>
79 constexpr bool is_floating_point_v = is_floating_point<_Tp>::value;
80template <typename _Tp>
81 constexpr bool is_array_v = is_array<_Tp>::value;
82template <typename _Tp>
83 constexpr bool is_pointer_v = is_pointer<_Tp>::value;
84template <typename _Tp>
85 constexpr bool is_lvalue_reference_v = is_lvalue_reference<_Tp>::value;
86template <typename _Tp>
87 constexpr bool is_rvalue_reference_v = is_rvalue_reference<_Tp>::value;
88template <typename _Tp>
89 constexpr bool is_member_object_pointer_v =
90 is_member_object_pointer<_Tp>::value;
91template <typename _Tp>
92 constexpr bool is_member_function_pointer_v =
93 is_member_function_pointer<_Tp>::value;
94template <typename _Tp>
95 constexpr bool is_enum_v = is_enum<_Tp>::value;
96template <typename _Tp>
97 constexpr bool is_union_v = is_union<_Tp>::value;
98template <typename _Tp>
99 constexpr bool is_class_v = is_class<_Tp>::value;
100template <typename _Tp>
101 constexpr bool is_function_v = is_function<_Tp>::value;
102
103// See C++14 20.10.4.2, composite type categories
104template <typename _Tp>
105 constexpr bool is_reference_v = is_reference<_Tp>::value;
106template <typename _Tp>
107 constexpr bool is_arithmetic_v = is_arithmetic<_Tp>::value;
108template <typename _Tp>
109 constexpr bool is_fundamental_v = is_fundamental<_Tp>::value;
110template <typename _Tp>
111 constexpr bool is_object_v = is_object<_Tp>::value;
112template <typename _Tp>
113 constexpr bool is_scalar_v = is_scalar<_Tp>::value;
114template <typename _Tp>
115 constexpr bool is_compound_v = is_compound<_Tp>::value;
116template <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
120template <typename _Tp>
121 constexpr bool is_const_v = is_const<_Tp>::value;
122template <typename _Tp>
123 constexpr bool is_volatile_v = is_volatile<_Tp>::value;
124#pragma GCC diagnostic push
125#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
126template <typename _Tp>
127 constexpr bool is_trivial_v = is_trivial<_Tp>::value;
128#pragma GCC diagnostic pop
129template <typename _Tp>
130 constexpr bool is_trivially_copyable_v = is_trivially_copyable<_Tp>::value;
131template <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"
135template <typename _Tp>
136 constexpr bool is_pod_v = is_pod<_Tp>::value;
137template <typename _Tp>
138 constexpr bool is_literal_type_v = is_literal_type<_Tp>::value;
139#pragma GCC diagnostic pop
140template <typename _Tp>
141 constexpr bool is_empty_v = is_empty<_Tp>::value;
142template <typename _Tp>
143 constexpr bool is_polymorphic_v = is_polymorphic<_Tp>::value;
144template <typename _Tp>
145 constexpr bool is_abstract_v = is_abstract<_Tp>::value;
146template <typename _Tp>
147 constexpr bool is_final_v = is_final<_Tp>::value;
148template <typename _Tp>
149 constexpr bool is_signed_v = is_signed<_Tp>::value;
150template <typename _Tp>
151 constexpr bool is_unsigned_v = is_unsigned<_Tp>::value;
152template <typename _Tp, typename... _Args>
153 constexpr bool is_constructible_v = is_constructible<_Tp, _Args...>::value;
154template <typename _Tp>
155 constexpr bool is_default_constructible_v =
156 is_default_constructible<_Tp>::value;
157template <typename _Tp>
158 constexpr bool is_copy_constructible_v = is_copy_constructible<_Tp>::value;
159template <typename _Tp>
160 constexpr bool is_move_constructible_v = is_move_constructible<_Tp>::value;
161template <typename _Tp, typename _Up>
162 constexpr bool is_assignable_v = is_assignable<_Tp, _Up>::value;
163template <typename _Tp>
164 constexpr bool is_copy_assignable_v = is_copy_assignable<_Tp>::value;
165template <typename _Tp>
166 constexpr bool is_move_assignable_v = is_move_assignable<_Tp>::value;
167template <typename _Tp>
168 constexpr bool is_destructible_v = is_destructible<_Tp>::value;
169template <typename _Tp, typename... _Args>
170 constexpr bool is_trivially_constructible_v =
171 is_trivially_constructible<_Tp, _Args...>::value;
172template <typename _Tp>
173 constexpr bool is_trivially_default_constructible_v =
174 is_trivially_default_constructible<_Tp>::value;
175template <typename _Tp>
176 constexpr bool is_trivially_copy_constructible_v =
177 is_trivially_copy_constructible<_Tp>::value;
178template <typename _Tp>
179 constexpr bool is_trivially_move_constructible_v =
180 is_trivially_move_constructible<_Tp>::value;
181template <typename _Tp, typename _Up>
182 constexpr bool is_trivially_assignable_v =
183 is_trivially_assignable<_Tp, _Up>::value;
184template <typename _Tp>
185 constexpr bool is_trivially_copy_assignable_v =
186 is_trivially_copy_assignable<_Tp>::value;
187template <typename _Tp>
188 constexpr bool is_trivially_move_assignable_v =
189 is_trivially_move_assignable<_Tp>::value;
190template <typename _Tp>
191 constexpr bool is_trivially_destructible_v =
192 is_trivially_destructible<_Tp>::value;
193template <typename _Tp, typename... _Args>
194 constexpr bool is_nothrow_constructible_v =
195 is_nothrow_constructible<_Tp, _Args...>::value;
196template <typename _Tp>
197 constexpr bool is_nothrow_default_constructible_v =
198 is_nothrow_default_constructible<_Tp>::value;
199template <typename _Tp>
200 constexpr bool is_nothrow_copy_constructible_v =
201 is_nothrow_copy_constructible<_Tp>::value;
202template <typename _Tp>
203 constexpr bool is_nothrow_move_constructible_v =
204 is_nothrow_move_constructible<_Tp>::value;
205template <typename _Tp, typename _Up>
206 constexpr bool is_nothrow_assignable_v =
207 is_nothrow_assignable<_Tp, _Up>::value;
208template <typename _Tp>
209 constexpr bool is_nothrow_copy_assignable_v =
210 is_nothrow_copy_assignable<_Tp>::value;
211template <typename _Tp>
212 constexpr bool is_nothrow_move_assignable_v =
213 is_nothrow_move_assignable<_Tp>::value;
214template <typename _Tp>
215 constexpr bool is_nothrow_destructible_v =
216 is_nothrow_destructible<_Tp>::value;
217template <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
222template <typename _Tp>
223 constexpr size_t alignment_of_v = alignment_of<_Tp>::value;
224template <typename _Tp>
225 constexpr size_t rank_v = rank<_Tp>::value;
226template <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
230template <typename _Tp, typename _Up>
231 constexpr bool is_same_v = false;
232template <typename _Tp>
233 constexpr bool is_same_v<_Tp, _Tp> = true;
234template <typename _Base, typename _Derived>
235 constexpr bool is_base_of_v = is_base_of<_Base, _Derived>::value;
236template <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
247inline 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
267struct __nonesuchbase {};
268struct 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
276template<typename _Default, template<typename...> class _Op, typename... _Args>
277 using detected_or = std::__detected_or<_Default, _Op, _Args...>;
278
279template<typename _Default, template<typename...> class _Op, typename... _Args>
280 using detected_or_t = typename detected_or<_Default, _Op, _Args...>::type;
281
282template<template<typename...> class _Op, typename... _Args>
283 using detected_t = detected_or_t<nonesuch, _Op, _Args...>;
284
285template<template<typename...> class _Op, typename... _Args>
286 using is_detected = typename detected_or<void, _Op, _Args...>::__is_detected;
287
288template<template<typename...> class _Op, typename... _Args>
289 constexpr bool is_detected_v = is_detected<_Op, _Args...>::value;
290
291template<typename _Expected, template<typename...> class _Op, typename... _Args>
292 using is_detected_exact = is_same<_Expected, detected_t<_Op, _Args...>>;
293
294template<typename _Expected, template<typename...> class _Op, typename... _Args>
295 constexpr bool is_detected_exact_v
296 = is_detected_exact<_Expected, _Op, _Args...>::value;
297
298template<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
317template<typename... _Bn>
318 struct conjunction
319 : __and_<_Bn...>
320 { };
321
322template<typename... _Bn>
323 struct disjunction
324 : __or_<_Bn...>
325 { };
326
327template<typename _Pp>
328 struct negation
329 : __not_<_Pp>
330 { };
331
332template<typename... _Bn>
333 constexpr bool conjunction_v
334 = conjunction<_Bn...>::value;
335
336template<typename... _Bn>
337 constexpr bool disjunction_v
338 = disjunction<_Bn...>::value;
339
340template<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
lfts_config.h
std::experimental::fundamentals_v2::is_detected_exact
is_same< _Expected, detected_t< _Op, _Args... > > is_detected_exact
A metafunction that always yields void, used for detecting valid types.
Definition experimental/type_traits:292
std::experimental::fundamentals_v2::is_detected_exact_v
constexpr bool is_detected_exact_v
A metafunction that always yields void, used for detecting valid types.
Definition experimental/type_traits:296
std::experimental::fundamentals_v2::detected_t
detected_or_t< nonesuch, _Op, _Args... > detected_t
A metafunction that always yields void, used for detecting valid types.
Definition experimental/type_traits:283
std::experimental::fundamentals_v2::void_t
void void_t
A metafunction that always yields void, used for detecting valid types.
Definition experimental/type_traits:262
std::experimental::fundamentals_v2::detected_or_t
typename detected_or< _Default, _Op, _Args... >::type detected_or_t
A metafunction that always yields void, used for detecting valid types.
Definition experimental/type_traits:280
std::experimental::fundamentals_v2::is_detected_convertible_v
constexpr bool is_detected_convertible_v
A metafunction that always yields void, used for detecting valid types.
Definition experimental/type_traits:303
std::experimental::fundamentals_v2::detected_or
std::__detected_or< _Default, _Op, _Args... > detected_or
A metafunction that always yields void, used for detecting valid types.
Definition experimental/type_traits:277
std::experimental::fundamentals_v2::is_detected_convertible
is_convertible< detected_t< _Op, _Args... >, _To > is_detected_convertible
A metafunction that always yields void, used for detecting valid types.
Definition experimental/type_traits:299
std::experimental::fundamentals_v2::is_detected
typename detected_or< void, _Op, _Args... >::__is_detected is_detected
A metafunction that always yields void, used for detecting valid types.
Definition experimental/type_traits:286
std::experimental::fundamentals_v2::is_detected_v
constexpr bool is_detected_v
A metafunction that always yields void, used for detecting valid types.
Definition experimental/type_traits:289
std
ISO C++ entities toplevel namespace is std.
std::experimental
Namespace for features defined in ISO Technical Specifications.
std::is_same
is_same
Definition type_traits:1649
type_traits