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197c757c TS |
1 | // <variant> -*- C++ -*- |
2 | ||
99dee823 | 3 | // Copyright (C) 2016-2021 Free Software Foundation, Inc. |
197c757c TS |
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 variant | |
f0b88346 | 26 | * This is the `<variant>` C++ Library header. |
197c757c TS |
27 | */ |
28 | ||
29 | #ifndef _GLIBCXX_VARIANT | |
30 | #define _GLIBCXX_VARIANT 1 | |
31 | ||
32 | #pragma GCC system_header | |
33 | ||
c6888c62 | 34 | #if __cplusplus >= 201703L |
197c757c TS |
35 | |
36 | #include <type_traits> | |
37 | #include <utility> | |
38 | #include <bits/enable_special_members.h> | |
45b510b3 | 39 | #include <bits/functexcept.h> |
f75d5999 | 40 | #include <bits/move.h> |
6964bb3e | 41 | #include <bits/functional_hash.h> |
b01af236 | 42 | #include <bits/invoke.h> |
9189f559 | 43 | #include <ext/aligned_buffer.h> |
f3df0b3c | 44 | #include <bits/parse_numbers.h> |
94895bd9 JW |
45 | #include <bits/stl_iterator_base_types.h> |
46 | #include <bits/stl_iterator_base_funcs.h> | |
47 | #include <bits/stl_construct.h> | |
9e589880 JW |
48 | #if __cplusplus > 201703L |
49 | # include <compare> | |
50 | #endif | |
197c757c TS |
51 | |
52 | namespace std _GLIBCXX_VISIBILITY(default) | |
53 | { | |
4a15d842 FD |
54 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
55 | ||
b01af236 TS |
56 | namespace __detail |
57 | { | |
58 | namespace __variant | |
59 | { | |
b01af236 TS |
60 | template<size_t _Np, typename... _Types> |
61 | struct _Nth_type; | |
62 | ||
63 | template<size_t _Np, typename _First, typename... _Rest> | |
64 | struct _Nth_type<_Np, _First, _Rest...> | |
65 | : _Nth_type<_Np-1, _Rest...> { }; | |
66 | ||
67 | template<typename _First, typename... _Rest> | |
68 | struct _Nth_type<0, _First, _Rest...> | |
69 | { using type = _First; }; | |
70 | ||
b01af236 TS |
71 | } // namespace __variant |
72 | } // namespace __detail | |
73 | ||
56a9eaf9 | 74 | #define __cpp_lib_variant 201606L |
c6888c62 | 75 | |
197c757c TS |
76 | template<typename... _Types> class tuple; |
77 | template<typename... _Types> class variant; | |
78 | template <typename> struct hash; | |
79 | ||
80 | template<typename _Variant> | |
81 | struct variant_size; | |
82 | ||
83 | template<typename _Variant> | |
84 | struct variant_size<const _Variant> : variant_size<_Variant> {}; | |
85 | ||
86 | template<typename _Variant> | |
87 | struct variant_size<volatile _Variant> : variant_size<_Variant> {}; | |
88 | ||
89 | template<typename _Variant> | |
90 | struct variant_size<const volatile _Variant> : variant_size<_Variant> {}; | |
91 | ||
92 | template<typename... _Types> | |
93 | struct variant_size<variant<_Types...>> | |
94 | : std::integral_constant<size_t, sizeof...(_Types)> {}; | |
95 | ||
96 | template<typename _Variant> | |
288695f7 | 97 | inline constexpr size_t variant_size_v = variant_size<_Variant>::value; |
197c757c TS |
98 | |
99 | template<size_t _Np, typename _Variant> | |
100 | struct variant_alternative; | |
101 | ||
102 | template<size_t _Np, typename _First, typename... _Rest> | |
103 | struct variant_alternative<_Np, variant<_First, _Rest...>> | |
104 | : variant_alternative<_Np-1, variant<_Rest...>> {}; | |
105 | ||
106 | template<typename _First, typename... _Rest> | |
107 | struct variant_alternative<0, variant<_First, _Rest...>> | |
108 | { using type = _First; }; | |
109 | ||
110 | template<size_t _Np, typename _Variant> | |
111 | using variant_alternative_t = | |
112 | typename variant_alternative<_Np, _Variant>::type; | |
113 | ||
3203ed5f TS |
114 | template<size_t _Np, typename _Variant> |
115 | struct variant_alternative<_Np, const _Variant> | |
116 | { using type = add_const_t<variant_alternative_t<_Np, _Variant>>; }; | |
117 | ||
118 | template<size_t _Np, typename _Variant> | |
119 | struct variant_alternative<_Np, volatile _Variant> | |
120 | { using type = add_volatile_t<variant_alternative_t<_Np, _Variant>>; }; | |
121 | ||
122 | template<size_t _Np, typename _Variant> | |
123 | struct variant_alternative<_Np, const volatile _Variant> | |
124 | { using type = add_cv_t<variant_alternative_t<_Np, _Variant>>; }; | |
125 | ||
288695f7 | 126 | inline constexpr size_t variant_npos = -1; |
197c757c | 127 | |
b01af236 TS |
128 | template<size_t _Np, typename... _Types> |
129 | constexpr variant_alternative_t<_Np, variant<_Types...>>& | |
130 | get(variant<_Types...>&); | |
131 | ||
132 | template<size_t _Np, typename... _Types> | |
133 | constexpr variant_alternative_t<_Np, variant<_Types...>>&& | |
134 | get(variant<_Types...>&&); | |
135 | ||
136 | template<size_t _Np, typename... _Types> | |
137 | constexpr variant_alternative_t<_Np, variant<_Types...>> const& | |
138 | get(const variant<_Types...>&); | |
139 | ||
140 | template<size_t _Np, typename... _Types> | |
141 | constexpr variant_alternative_t<_Np, variant<_Types...>> const&& | |
142 | get(const variant<_Types...>&&); | |
143 | ||
956a62aa | 144 | template<typename _Result_type, typename _Visitor, typename... _Variants> |
669a6fdc VV |
145 | constexpr decltype(auto) |
146 | __do_visit(_Visitor&& __visitor, _Variants&&... __variants); | |
147 | ||
148 | template <typename... _Types, typename _Tp> | |
9d89b73c JW |
149 | decltype(auto) |
150 | __variant_cast(_Tp&& __rhs) | |
669a6fdc VV |
151 | { |
152 | if constexpr (is_lvalue_reference_v<_Tp>) | |
153 | { | |
154 | if constexpr (is_const_v<remove_reference_t<_Tp>>) | |
155 | return static_cast<const variant<_Types...>&>(__rhs); | |
156 | else | |
157 | return static_cast<variant<_Types...>&>(__rhs); | |
158 | } | |
159 | else | |
160 | return static_cast<variant<_Types...>&&>(__rhs); | |
161 | } | |
162 | ||
197c757c TS |
163 | namespace __detail |
164 | { | |
165 | namespace __variant | |
166 | { | |
c98fc4eb | 167 | // Returns the first appearance of _Tp in _Types. |
197c757c TS |
168 | // Returns sizeof...(_Types) if _Tp is not in _Types. |
169 | template<typename _Tp, typename... _Types> | |
170 | struct __index_of : std::integral_constant<size_t, 0> {}; | |
171 | ||
172 | template<typename _Tp, typename... _Types> | |
288695f7 | 173 | inline constexpr size_t __index_of_v = __index_of<_Tp, _Types...>::value; |
197c757c TS |
174 | |
175 | template<typename _Tp, typename _First, typename... _Rest> | |
176 | struct __index_of<_Tp, _First, _Rest...> : | |
177 | std::integral_constant<size_t, is_same_v<_Tp, _First> | |
178 | ? 0 : __index_of_v<_Tp, _Rest...> + 1> {}; | |
179 | ||
669a6fdc VV |
180 | // used for raw visitation |
181 | struct __variant_cookie {}; | |
f1ba6c5a | 182 | // used for raw visitation with indices passed in |
8701cb5e | 183 | struct __variant_idx_cookie { using type = __variant_idx_cookie; }; |
956a62aa | 184 | // Used to enable deduction (and same-type checking) for std::visit: |
3427e313 | 185 | template<typename _Tp> struct __deduce_visit_result { using type = _Tp; }; |
956a62aa JW |
186 | |
187 | // Visit variants that might be valueless. | |
188 | template<typename _Visitor, typename... _Variants> | |
189 | constexpr void | |
190 | __raw_visit(_Visitor&& __visitor, _Variants&&... __variants) | |
191 | { | |
192 | std::__do_visit<__variant_cookie>(std::forward<_Visitor>(__visitor), | |
193 | std::forward<_Variants>(__variants)...); | |
194 | } | |
195 | ||
196 | // Visit variants that might be valueless, passing indices to the visitor. | |
197 | template<typename _Visitor, typename... _Variants> | |
198 | constexpr void | |
199 | __raw_idx_visit(_Visitor&& __visitor, _Variants&&... __variants) | |
200 | { | |
201 | std::__do_visit<__variant_idx_cookie>(std::forward<_Visitor>(__visitor), | |
202 | std::forward<_Variants>(__variants)...); | |
203 | } | |
669a6fdc | 204 | |
24b54628 VV |
205 | // _Uninitialized<T> is guaranteed to be a trivially destructible type, |
206 | // even if T is not. | |
207 | template<typename _Type, bool = std::is_trivially_destructible_v<_Type>> | |
197c757c TS |
208 | struct _Uninitialized; |
209 | ||
210 | template<typename _Type> | |
211 | struct _Uninitialized<_Type, true> | |
212 | { | |
197c757c | 213 | template<typename... _Args> |
9d89b73c JW |
214 | constexpr |
215 | _Uninitialized(in_place_index_t<0>, _Args&&... __args) | |
216 | : _M_storage(std::forward<_Args>(__args)...) | |
217 | { } | |
197c757c | 218 | |
be46043e | 219 | constexpr const _Type& _M_get() const & noexcept |
9189f559 TS |
220 | { return _M_storage; } |
221 | ||
be46043e | 222 | constexpr _Type& _M_get() & noexcept |
9189f559 TS |
223 | { return _M_storage; } |
224 | ||
be46043e | 225 | constexpr const _Type&& _M_get() const && noexcept |
9189f559 TS |
226 | { return std::move(_M_storage); } |
227 | ||
be46043e | 228 | constexpr _Type&& _M_get() && noexcept |
9189f559 TS |
229 | { return std::move(_M_storage); } |
230 | ||
197c757c TS |
231 | _Type _M_storage; |
232 | }; | |
233 | ||
234 | template<typename _Type> | |
235 | struct _Uninitialized<_Type, false> | |
236 | { | |
197c757c | 237 | template<typename... _Args> |
9d89b73c JW |
238 | constexpr |
239 | _Uninitialized(in_place_index_t<0>, _Args&&... __args) | |
240 | { | |
241 | ::new ((void*)std::addressof(_M_storage)) | |
242 | _Type(std::forward<_Args>(__args)...); | |
243 | } | |
197c757c | 244 | |
be46043e | 245 | const _Type& _M_get() const & noexcept |
9189f559 TS |
246 | { return *_M_storage._M_ptr(); } |
247 | ||
be46043e | 248 | _Type& _M_get() & noexcept |
9189f559 TS |
249 | { return *_M_storage._M_ptr(); } |
250 | ||
be46043e | 251 | const _Type&& _M_get() const && noexcept |
9189f559 TS |
252 | { return std::move(*_M_storage._M_ptr()); } |
253 | ||
be46043e | 254 | _Type&& _M_get() && noexcept |
9189f559 TS |
255 | { return std::move(*_M_storage._M_ptr()); } |
256 | ||
257 | __gnu_cxx::__aligned_membuf<_Type> _M_storage; | |
197c757c TS |
258 | }; |
259 | ||
9189f559 | 260 | template<typename _Union> |
be46043e JW |
261 | constexpr decltype(auto) |
262 | __get(in_place_index_t<0>, _Union&& __u) noexcept | |
9189f559 TS |
263 | { return std::forward<_Union>(__u)._M_first._M_get(); } |
264 | ||
265 | template<size_t _Np, typename _Union> | |
be46043e JW |
266 | constexpr decltype(auto) |
267 | __get(in_place_index_t<_Np>, _Union&& __u) noexcept | |
aafaa325 JW |
268 | { |
269 | return __variant::__get(in_place_index<_Np-1>, | |
270 | std::forward<_Union>(__u)._M_rest); | |
271 | } | |
9189f559 TS |
272 | |
273 | // Returns the typed storage for __v. | |
274 | template<size_t _Np, typename _Variant> | |
be46043e JW |
275 | constexpr decltype(auto) |
276 | __get(_Variant&& __v) noexcept | |
9189f559 | 277 | { |
aafaa325 JW |
278 | return __variant::__get(std::in_place_index<_Np>, |
279 | std::forward<_Variant>(__v)._M_u); | |
9189f559 TS |
280 | } |
281 | ||
70503724 TS |
282 | template<typename... _Types> |
283 | struct _Traits | |
284 | { | |
285 | static constexpr bool _S_default_ctor = | |
4a15d842 | 286 | is_default_constructible_v<typename _Nth_type<0, _Types...>::type>; |
70503724 | 287 | static constexpr bool _S_copy_ctor = |
4a15d842 | 288 | (is_copy_constructible_v<_Types> && ...); |
70503724 | 289 | static constexpr bool _S_move_ctor = |
4a15d842 | 290 | (is_move_constructible_v<_Types> && ...); |
70503724 | 291 | static constexpr bool _S_copy_assign = |
5f00d0d5 | 292 | _S_copy_ctor |
4a15d842 | 293 | && (is_copy_assignable_v<_Types> && ...); |
70503724 | 294 | static constexpr bool _S_move_assign = |
4a15d842 FD |
295 | _S_move_ctor |
296 | && (is_move_assignable_v<_Types> && ...); | |
70503724 TS |
297 | |
298 | static constexpr bool _S_trivial_dtor = | |
4a15d842 | 299 | (is_trivially_destructible_v<_Types> && ...); |
70503724 | 300 | static constexpr bool _S_trivial_copy_ctor = |
4a15d842 | 301 | (is_trivially_copy_constructible_v<_Types> && ...); |
70503724 | 302 | static constexpr bool _S_trivial_move_ctor = |
4a15d842 | 303 | (is_trivially_move_constructible_v<_Types> && ...); |
70503724 | 304 | static constexpr bool _S_trivial_copy_assign = |
038bc9bf JW |
305 | _S_trivial_dtor && _S_trivial_copy_ctor |
306 | && (is_trivially_copy_assignable_v<_Types> && ...); | |
70503724 | 307 | static constexpr bool _S_trivial_move_assign = |
038bc9bf JW |
308 | _S_trivial_dtor && _S_trivial_move_ctor |
309 | && (is_trivially_move_assignable_v<_Types> && ...); | |
70503724 TS |
310 | |
311 | // The following nothrow traits are for non-trivial SMFs. Trivial SMFs | |
312 | // are always nothrow. | |
313 | static constexpr bool _S_nothrow_default_ctor = | |
4a15d842 FD |
314 | is_nothrow_default_constructible_v< |
315 | typename _Nth_type<0, _Types...>::type>; | |
70503724 TS |
316 | static constexpr bool _S_nothrow_copy_ctor = false; |
317 | static constexpr bool _S_nothrow_move_ctor = | |
4a15d842 | 318 | (is_nothrow_move_constructible_v<_Types> && ...); |
70503724 TS |
319 | static constexpr bool _S_nothrow_copy_assign = false; |
320 | static constexpr bool _S_nothrow_move_assign = | |
038bc9bf JW |
321 | _S_nothrow_move_ctor |
322 | && (is_nothrow_move_assignable_v<_Types> && ...); | |
70503724 TS |
323 | }; |
324 | ||
9189f559 | 325 | // Defines members and ctors. |
197c757c | 326 | template<typename... _Types> |
9189f559 | 327 | union _Variadic_union { }; |
197c757c | 328 | |
197c757c | 329 | template<typename _First, typename... _Rest> |
9189f559 | 330 | union _Variadic_union<_First, _Rest...> |
197c757c | 331 | { |
9189f559 TS |
332 | constexpr _Variadic_union() : _M_rest() { } |
333 | ||
334 | template<typename... _Args> | |
335 | constexpr _Variadic_union(in_place_index_t<0>, _Args&&... __args) | |
336 | : _M_first(in_place_index<0>, std::forward<_Args>(__args)...) | |
337 | { } | |
338 | ||
339 | template<size_t _Np, typename... _Args> | |
340 | constexpr _Variadic_union(in_place_index_t<_Np>, _Args&&... __args) | |
341 | : _M_rest(in_place_index<_Np-1>, std::forward<_Args>(__args)...) | |
342 | { } | |
343 | ||
344 | _Uninitialized<_First> _M_first; | |
345 | _Variadic_union<_Rest...> _M_rest; | |
346 | }; | |
347 | ||
10f26de9 JW |
348 | // _Never_valueless_alt is true for variant alternatives that can |
349 | // always be placed in a variant without it becoming valueless. | |
350 | ||
351 | // For suitably-small, trivially copyable types we can create temporaries | |
352 | // on the stack and then memcpy them into place. | |
353 | template<typename _Tp> | |
354 | struct _Never_valueless_alt | |
355 | : __and_<bool_constant<sizeof(_Tp) <= 256>, is_trivially_copyable<_Tp>> | |
356 | { }; | |
357 | ||
358 | // Specialize _Never_valueless_alt for other types which have a | |
47a468bd JW |
359 | // non-throwing and cheap move construction and move assignment operator, |
360 | // so that emplacing the type will provide the strong exception-safety | |
361 | // guarantee, by creating and moving a temporary. | |
10f26de9 JW |
362 | // Whether _Never_valueless_alt<T> is true or not affects the ABI of a |
363 | // variant using that alternative, so we can't change the value later! | |
364 | ||
365 | // True if every alternative in _Types... can be emplaced in a variant | |
366 | // without it becoming valueless. If this is true, variant<_Types...> | |
367 | // can never be valueless, which enables some minor optimizations. | |
da97b98a | 368 | template <typename... _Types> |
10f26de9 JW |
369 | constexpr bool __never_valueless() |
370 | { | |
47a468bd JW |
371 | return _Traits<_Types...>::_S_move_assign |
372 | && (_Never_valueless_alt<_Types>::value && ...); | |
10f26de9 | 373 | } |
da97b98a | 374 | |
9189f559 TS |
375 | // Defines index and the dtor, possibly trivial. |
376 | template<bool __trivially_destructible, typename... _Types> | |
377 | struct _Variant_storage; | |
378 | ||
f3df0b3c | 379 | template <typename... _Types> |
9d89b73c JW |
380 | using __select_index = |
381 | typename __select_int::_Select_int_base<sizeof...(_Types), | |
382 | unsigned char, | |
383 | unsigned short>::type::value_type; | |
f3df0b3c | 384 | |
9189f559 TS |
385 | template<typename... _Types> |
386 | struct _Variant_storage<false, _Types...> | |
387 | { | |
074436cf JW |
388 | constexpr |
389 | _Variant_storage() | |
390 | : _M_index(static_cast<__index_type>(variant_npos)) | |
391 | { } | |
197c757c | 392 | |
41501d1a | 393 | template<size_t _Np, typename... _Args> |
074436cf JW |
394 | constexpr |
395 | _Variant_storage(in_place_index_t<_Np>, _Args&&... __args) | |
9189f559 | 396 | : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...), |
074436cf | 397 | _M_index{_Np} |
197c757c TS |
398 | { } |
399 | ||
b62dcd16 | 400 | void _M_reset() |
669a6fdc | 401 | { |
b62dcd16 JW |
402 | if (!_M_valid()) [[unlikely]] |
403 | return; | |
404 | ||
405 | std::__do_visit<void>([](auto&& __this_mem) mutable | |
669a6fdc | 406 | { |
b62dcd16 | 407 | std::_Destroy(std::__addressof(__this_mem)); |
669a6fdc | 408 | }, __variant_cast<_Types...>(*this)); |
197c757c | 409 | |
074436cf | 410 | _M_index = static_cast<__index_type>(variant_npos); |
458ef690 TS |
411 | } |
412 | ||
9189f559 | 413 | ~_Variant_storage() |
458ef690 | 414 | { _M_reset(); } |
197c757c | 415 | |
70503724 | 416 | void* |
4b7a3ab8 | 417 | _M_storage() const noexcept |
70503724 TS |
418 | { |
419 | return const_cast<void*>(static_cast<const void*>( | |
420 | std::addressof(_M_u))); | |
421 | } | |
422 | ||
423 | constexpr bool | |
424 | _M_valid() const noexcept | |
425 | { | |
d306dee3 | 426 | if constexpr (__variant::__never_valueless<_Types...>()) |
47a468bd | 427 | return true; |
70503724 TS |
428 | return this->_M_index != __index_type(variant_npos); |
429 | } | |
430 | ||
9189f559 | 431 | _Variadic_union<_Types...> _M_u; |
f3df0b3c VV |
432 | using __index_type = __select_index<_Types...>; |
433 | __index_type _M_index; | |
197c757c TS |
434 | }; |
435 | ||
9189f559 TS |
436 | template<typename... _Types> |
437 | struct _Variant_storage<true, _Types...> | |
197c757c | 438 | { |
074436cf JW |
439 | constexpr |
440 | _Variant_storage() | |
441 | : _M_index(static_cast<__index_type>(variant_npos)) | |
442 | { } | |
197c757c | 443 | |
9189f559 | 444 | template<size_t _Np, typename... _Args> |
074436cf JW |
445 | constexpr |
446 | _Variant_storage(in_place_index_t<_Np>, _Args&&... __args) | |
9189f559 | 447 | : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...), |
074436cf | 448 | _M_index{_Np} |
9189f559 TS |
449 | { } |
450 | ||
4b7a3ab8 | 451 | void _M_reset() noexcept |
074436cf | 452 | { _M_index = static_cast<__index_type>(variant_npos); } |
458ef690 | 453 | |
70503724 | 454 | void* |
4b7a3ab8 | 455 | _M_storage() const noexcept |
70503724 TS |
456 | { |
457 | return const_cast<void*>(static_cast<const void*>( | |
458 | std::addressof(_M_u))); | |
459 | } | |
460 | ||
461 | constexpr bool | |
462 | _M_valid() const noexcept | |
463 | { | |
d306dee3 | 464 | if constexpr (__variant::__never_valueless<_Types...>()) |
16d30bbd | 465 | return true; |
074436cf | 466 | return this->_M_index != static_cast<__index_type>(variant_npos); |
70503724 TS |
467 | } |
468 | ||
9189f559 | 469 | _Variadic_union<_Types...> _M_u; |
f3df0b3c VV |
470 | using __index_type = __select_index<_Types...>; |
471 | __index_type _M_index; | |
197c757c TS |
472 | }; |
473 | ||
197c757c | 474 | template<typename... _Types> |
70503724 | 475 | using _Variant_storage_alias = |
4a15d842 | 476 | _Variant_storage<_Traits<_Types...>::_S_trivial_dtor, _Types...>; |
197c757c | 477 | |
337d1fec VV |
478 | template<typename _Tp, typename _Up> |
479 | void __variant_construct_single(_Tp&& __lhs, _Up&& __rhs_mem) | |
480 | { | |
481 | void* __storage = std::addressof(__lhs._M_u); | |
482 | using _Type = remove_reference_t<decltype(__rhs_mem)>; | |
483 | if constexpr (!is_same_v<_Type, __variant_cookie>) | |
484 | ::new (__storage) | |
485 | _Type(std::forward<decltype(__rhs_mem)>(__rhs_mem)); | |
486 | } | |
487 | ||
669a6fdc VV |
488 | template<typename... _Types, typename _Tp, typename _Up> |
489 | void __variant_construct(_Tp&& __lhs, _Up&& __rhs) | |
490 | { | |
491 | __lhs._M_index = __rhs._M_index; | |
956a62aa | 492 | __variant::__raw_visit([&__lhs](auto&& __rhs_mem) mutable |
669a6fdc | 493 | { |
337d1fec | 494 | __variant_construct_single(std::forward<_Tp>(__lhs), |
86a57ce1 | 495 | std::forward<decltype(__rhs_mem)>(__rhs_mem)); |
86a57ce1 | 496 | }, __variant_cast<_Types...>(std::forward<_Up>(__rhs))); |
669a6fdc VV |
497 | } |
498 | ||
70503724 TS |
499 | // The following are (Copy|Move) (ctor|assign) layers for forwarding |
500 | // triviality and handling non-trivial SMF behaviors. | |
501 | ||
502 | template<bool, typename... _Types> | |
503 | struct _Copy_ctor_base : _Variant_storage_alias<_Types...> | |
504 | { | |
505 | using _Base = _Variant_storage_alias<_Types...>; | |
506 | using _Base::_Base; | |
197c757c | 507 | |
70503724 | 508 | _Copy_ctor_base(const _Copy_ctor_base& __rhs) |
4a15d842 | 509 | noexcept(_Traits<_Types...>::_S_nothrow_copy_ctor) |
197c757c | 510 | { |
669a6fdc | 511 | __variant_construct<_Types...>(*this, __rhs); |
197c757c TS |
512 | } |
513 | ||
70503724 TS |
514 | _Copy_ctor_base(_Copy_ctor_base&&) = default; |
515 | _Copy_ctor_base& operator=(const _Copy_ctor_base&) = default; | |
516 | _Copy_ctor_base& operator=(_Copy_ctor_base&&) = default; | |
517 | }; | |
518 | ||
519 | template<typename... _Types> | |
520 | struct _Copy_ctor_base<true, _Types...> : _Variant_storage_alias<_Types...> | |
521 | { | |
522 | using _Base = _Variant_storage_alias<_Types...>; | |
523 | using _Base::_Base; | |
524 | }; | |
525 | ||
526 | template<typename... _Types> | |
527 | using _Copy_ctor_alias = | |
4a15d842 | 528 | _Copy_ctor_base<_Traits<_Types...>::_S_trivial_copy_ctor, _Types...>; |
70503724 TS |
529 | |
530 | template<bool, typename... _Types> | |
531 | struct _Move_ctor_base : _Copy_ctor_alias<_Types...> | |
532 | { | |
533 | using _Base = _Copy_ctor_alias<_Types...>; | |
534 | using _Base::_Base; | |
535 | ||
536 | _Move_ctor_base(_Move_ctor_base&& __rhs) | |
4a15d842 | 537 | noexcept(_Traits<_Types...>::_S_nothrow_move_ctor) |
197c757c | 538 | { |
86a57ce1 | 539 | __variant_construct<_Types...>(*this, std::move(__rhs)); |
669a6fdc VV |
540 | } |
541 | ||
337d1fec VV |
542 | template<typename _Up> |
543 | void _M_destructive_move(unsigned short __rhs_index, _Up&& __rhs) | |
544 | { | |
545 | this->_M_reset(); | |
86a57ce1 | 546 | __variant_construct_single(*this, std::forward<_Up>(__rhs)); |
337d1fec | 547 | this->_M_index = __rhs_index; |
337d1fec | 548 | } |
197c757c | 549 | |
337d1fec VV |
550 | template<typename _Up> |
551 | void _M_destructive_copy(unsigned short __rhs_index, const _Up& __rhs) | |
552 | { | |
553 | this->_M_reset(); | |
86a57ce1 | 554 | __variant_construct_single(*this, __rhs); |
337d1fec | 555 | this->_M_index = __rhs_index; |
337d1fec | 556 | } |
0ec78a93 | 557 | |
70503724 TS |
558 | _Move_ctor_base(const _Move_ctor_base&) = default; |
559 | _Move_ctor_base& operator=(const _Move_ctor_base&) = default; | |
560 | _Move_ctor_base& operator=(_Move_ctor_base&&) = default; | |
561 | }; | |
562 | ||
563 | template<typename... _Types> | |
564 | struct _Move_ctor_base<true, _Types...> : _Copy_ctor_alias<_Types...> | |
565 | { | |
566 | using _Base = _Copy_ctor_alias<_Types...>; | |
567 | using _Base::_Base; | |
0ec78a93 | 568 | |
337d1fec VV |
569 | template<typename _Up> |
570 | void _M_destructive_move(unsigned short __rhs_index, _Up&& __rhs) | |
571 | { | |
572 | this->_M_reset(); | |
86a57ce1 | 573 | __variant_construct_single(*this, std::forward<_Up>(__rhs)); |
337d1fec | 574 | this->_M_index = __rhs_index; |
337d1fec | 575 | } |
9d89b73c | 576 | |
337d1fec VV |
577 | template<typename _Up> |
578 | void _M_destructive_copy(unsigned short __rhs_index, const _Up& __rhs) | |
579 | { | |
580 | this->_M_reset(); | |
337d1fec | 581 | __variant_construct_single(*this, __rhs); |
86a57ce1 | 582 | this->_M_index = __rhs_index; |
337d1fec | 583 | } |
70503724 TS |
584 | }; |
585 | ||
586 | template<typename... _Types> | |
587 | using _Move_ctor_alias = | |
4a15d842 | 588 | _Move_ctor_base<_Traits<_Types...>::_S_trivial_move_ctor, _Types...>; |
70503724 TS |
589 | |
590 | template<bool, typename... _Types> | |
591 | struct _Copy_assign_base : _Move_ctor_alias<_Types...> | |
592 | { | |
593 | using _Base = _Move_ctor_alias<_Types...>; | |
594 | using _Base::_Base; | |
197c757c | 595 | |
70503724 TS |
596 | _Copy_assign_base& |
597 | operator=(const _Copy_assign_base& __rhs) | |
4a15d842 | 598 | noexcept(_Traits<_Types...>::_S_nothrow_copy_assign) |
197c757c | 599 | { |
956a62aa JW |
600 | __variant::__raw_idx_visit( |
601 | [this](auto&& __rhs_mem, auto __rhs_index) mutable | |
197c757c | 602 | { |
f1ba6c5a | 603 | if constexpr (__rhs_index != variant_npos) |
197c757c | 604 | { |
f1ba6c5a | 605 | if (this->_M_index == __rhs_index) |
86a57ce1 | 606 | __variant::__get<__rhs_index>(*this) = __rhs_mem; |
f1ba6c5a VV |
607 | else |
608 | { | |
86a57ce1 JW |
609 | using __rhs_type = __remove_cvref_t<decltype(__rhs_mem)>; |
610 | if constexpr (is_nothrow_copy_constructible_v<__rhs_type> | |
611 | || !is_nothrow_move_constructible_v<__rhs_type>) | |
612 | // The standard says this->emplace<__rhs_type>(__rhs_mem) | |
613 | // should be used here, but _M_destructive_copy is | |
614 | // equivalent in this case. Either copy construction | |
615 | // doesn't throw, so _M_destructive_copy gives strong | |
616 | // exception safety guarantee, or both copy construction | |
617 | // and move construction can throw, so emplace only gives | |
618 | // basic exception safety anyway. | |
619 | this->_M_destructive_copy(__rhs_index, __rhs_mem); | |
669a6fdc | 620 | else |
86a57ce1 | 621 | __variant_cast<_Types...>(*this) |
dbca7a69 VV |
622 | = variant<_Types...>(std::in_place_index<__rhs_index>, |
623 | __rhs_mem); | |
669a6fdc | 624 | } |
669a6fdc | 625 | } |
f1ba6c5a VV |
626 | else |
627 | this->_M_reset(); | |
f1ba6c5a | 628 | }, __variant_cast<_Types...>(__rhs)); |
197c757c TS |
629 | return *this; |
630 | } | |
631 | ||
70503724 TS |
632 | _Copy_assign_base(const _Copy_assign_base&) = default; |
633 | _Copy_assign_base(_Copy_assign_base&&) = default; | |
634 | _Copy_assign_base& operator=(_Copy_assign_base&&) = default; | |
635 | }; | |
636 | ||
637 | template<typename... _Types> | |
638 | struct _Copy_assign_base<true, _Types...> : _Move_ctor_alias<_Types...> | |
639 | { | |
640 | using _Base = _Move_ctor_alias<_Types...>; | |
641 | using _Base::_Base; | |
642 | }; | |
643 | ||
644 | template<typename... _Types> | |
645 | using _Copy_assign_alias = | |
038bc9bf | 646 | _Copy_assign_base<_Traits<_Types...>::_S_trivial_copy_assign, _Types...>; |
70503724 TS |
647 | |
648 | template<bool, typename... _Types> | |
649 | struct _Move_assign_base : _Copy_assign_alias<_Types...> | |
650 | { | |
651 | using _Base = _Copy_assign_alias<_Types...>; | |
652 | using _Base::_Base; | |
653 | ||
70503724 TS |
654 | _Move_assign_base& |
655 | operator=(_Move_assign_base&& __rhs) | |
4a15d842 | 656 | noexcept(_Traits<_Types...>::_S_nothrow_move_assign) |
197c757c | 657 | { |
956a62aa JW |
658 | __variant::__raw_idx_visit( |
659 | [this](auto&& __rhs_mem, auto __rhs_index) mutable | |
197c757c | 660 | { |
f1ba6c5a | 661 | if constexpr (__rhs_index != variant_npos) |
197c757c | 662 | { |
f1ba6c5a | 663 | if (this->_M_index == __rhs_index) |
86a57ce1 | 664 | __variant::__get<__rhs_index>(*this) = std::move(__rhs_mem); |
f1ba6c5a | 665 | else |
86a57ce1 JW |
666 | __variant_cast<_Types...>(*this) |
667 | .template emplace<__rhs_index>(std::move(__rhs_mem)); | |
197c757c | 668 | } |
669a6fdc | 669 | else |
f1ba6c5a | 670 | this->_M_reset(); |
f1ba6c5a | 671 | }, __variant_cast<_Types...>(__rhs)); |
197c757c TS |
672 | return *this; |
673 | } | |
674 | ||
70503724 TS |
675 | _Move_assign_base(const _Move_assign_base&) = default; |
676 | _Move_assign_base(_Move_assign_base&&) = default; | |
677 | _Move_assign_base& operator=(const _Move_assign_base&) = default; | |
678 | }; | |
197c757c | 679 | |
70503724 TS |
680 | template<typename... _Types> |
681 | struct _Move_assign_base<true, _Types...> : _Copy_assign_alias<_Types...> | |
682 | { | |
683 | using _Base = _Copy_assign_alias<_Types...>; | |
684 | using _Base::_Base; | |
685 | }; | |
686 | ||
687 | template<typename... _Types> | |
688 | using _Move_assign_alias = | |
9d89b73c | 689 | _Move_assign_base<_Traits<_Types...>::_S_trivial_move_assign, _Types...>; |
70503724 TS |
690 | |
691 | template<typename... _Types> | |
692 | struct _Variant_base : _Move_assign_alias<_Types...> | |
693 | { | |
694 | using _Base = _Move_assign_alias<_Types...>; | |
695 | ||
696 | constexpr | |
697 | _Variant_base() | |
4a15d842 | 698 | noexcept(_Traits<_Types...>::_S_nothrow_default_ctor) |
70503724 TS |
699 | : _Variant_base(in_place_index<0>) { } |
700 | ||
701 | template<size_t _Np, typename... _Args> | |
702 | constexpr explicit | |
703 | _Variant_base(in_place_index_t<_Np> __i, _Args&&... __args) | |
704 | : _Base(__i, std::forward<_Args>(__args)...) | |
705 | { } | |
706 | ||
707 | _Variant_base(const _Variant_base&) = default; | |
708 | _Variant_base(_Variant_base&&) = default; | |
709 | _Variant_base& operator=(const _Variant_base&) = default; | |
710 | _Variant_base& operator=(_Variant_base&&) = default; | |
197c757c TS |
711 | }; |
712 | ||
713 | // For how many times does _Tp appear in _Tuple? | |
714 | template<typename _Tp, typename _Tuple> | |
715 | struct __tuple_count; | |
716 | ||
717 | template<typename _Tp, typename _Tuple> | |
288695f7 DK |
718 | inline constexpr size_t __tuple_count_v = |
719 | __tuple_count<_Tp, _Tuple>::value; | |
197c757c TS |
720 | |
721 | template<typename _Tp, typename... _Types> | |
722 | struct __tuple_count<_Tp, tuple<_Types...>> | |
723 | : integral_constant<size_t, 0> { }; | |
724 | ||
725 | template<typename _Tp, typename _First, typename... _Rest> | |
726 | struct __tuple_count<_Tp, tuple<_First, _Rest...>> | |
727 | : integral_constant< | |
728 | size_t, | |
729 | __tuple_count_v<_Tp, tuple<_Rest...>> + is_same_v<_Tp, _First>> { }; | |
730 | ||
731 | // TODO: Reuse this in <tuple> ? | |
732 | template<typename _Tp, typename... _Types> | |
288695f7 DK |
733 | inline constexpr bool __exactly_once = |
734 | __tuple_count_v<_Tp, tuple<_Types...>> == 1; | |
197c757c | 735 | |
d069df01 JW |
736 | // Helper used to check for valid conversions that don't involve narrowing. |
737 | template<typename _Ti> struct _Arr { _Ti _M_x[1]; }; | |
197c757c | 738 | |
c98fc4eb JW |
739 | // "Build an imaginary function FUN(Ti) for each alternative type Ti" |
740 | template<size_t _Ind, typename _Tp, typename _Ti, typename = void> | |
d069df01 | 741 | struct _Build_FUN |
197c757c | 742 | { |
d069df01 JW |
743 | // This function means 'using _Build_FUN<I, T, Ti>::_S_fun;' is valid, |
744 | // but only static functions will be considered in the call below. | |
745 | void _S_fun(); | |
197c757c TS |
746 | }; |
747 | ||
c98fc4eb | 748 | // "... for which Ti x[] = {std::forward<T>(t)}; is well-formed." |
d069df01 | 749 | template<size_t _Ind, typename _Tp, typename _Ti> |
c98fc4eb | 750 | struct _Build_FUN<_Ind, _Tp, _Ti, |
d069df01 | 751 | void_t<decltype(_Arr<_Ti>{{std::declval<_Tp>()}})>> |
197c757c | 752 | { |
d069df01 JW |
753 | // This is the FUN function for type _Ti, with index _Ind |
754 | static integral_constant<size_t, _Ind> _S_fun(_Ti); | |
197c757c TS |
755 | }; |
756 | ||
d069df01 JW |
757 | template<typename _Tp, typename _Variant, |
758 | typename = make_index_sequence<variant_size_v<_Variant>>> | |
759 | struct _Build_FUNs; | |
760 | ||
761 | template<typename _Tp, typename... _Ti, size_t... _Ind> | |
762 | struct _Build_FUNs<_Tp, variant<_Ti...>, index_sequence<_Ind...>> | |
763 | : _Build_FUN<_Ind, _Tp, _Ti>... | |
197c757c | 764 | { |
d069df01 | 765 | using _Build_FUN<_Ind, _Tp, _Ti>::_S_fun...; |
197c757c TS |
766 | }; |
767 | ||
d069df01 JW |
768 | // The index j of the overload FUN(Tj) selected by overload resolution |
769 | // for FUN(std::forward<_Tp>(t)) | |
770 | template<typename _Tp, typename _Variant> | |
771 | using _FUN_type | |
772 | = decltype(_Build_FUNs<_Tp, _Variant>::_S_fun(std::declval<_Tp>())); | |
773 | ||
774 | // The index selected for FUN(std::forward<T>(t)), or variant_npos if none. | |
775 | template<typename _Tp, typename _Variant, typename = void> | |
776 | struct __accepted_index | |
777 | : integral_constant<size_t, variant_npos> | |
778 | { }; | |
779 | ||
780 | template<typename _Tp, typename _Variant> | |
781 | struct __accepted_index<_Tp, _Variant, void_t<_FUN_type<_Tp, _Variant>>> | |
782 | : _FUN_type<_Tp, _Variant> | |
783 | { }; | |
784 | ||
197c757c TS |
785 | // Returns the raw storage for __v. |
786 | template<typename _Variant> | |
4b7a3ab8 | 787 | void* __get_storage(_Variant&& __v) noexcept |
197c757c TS |
788 | { return __v._M_storage(); } |
789 | ||
da97b98a | 790 | template <typename _Maybe_variant_cookie, typename _Variant> |
10f26de9 JW |
791 | struct _Extra_visit_slot_needed |
792 | { | |
793 | template <typename> struct _Variant_never_valueless; | |
da97b98a | 794 | |
10f26de9 JW |
795 | template <typename... _Types> |
796 | struct _Variant_never_valueless<variant<_Types...>> | |
d306dee3 | 797 | : bool_constant<__variant::__never_valueless<_Types...>()> {}; |
da97b98a | 798 | |
10f26de9 JW |
799 | static constexpr bool value = |
800 | (is_same_v<_Maybe_variant_cookie, __variant_cookie> | |
801 | || is_same_v<_Maybe_variant_cookie, __variant_idx_cookie>) | |
802 | && !_Variant_never_valueless<__remove_cvref_t<_Variant>>::value; | |
803 | }; | |
da97b98a | 804 | |
9d89b73c | 805 | // Used for storing a multi-dimensional vtable. |
197c757c | 806 | template<typename _Tp, size_t... _Dimensions> |
9d89b73c JW |
807 | struct _Multi_array; |
808 | ||
809 | // Partial specialization with rank zero, stores a single _Tp element. | |
810 | template<typename _Tp> | |
811 | struct _Multi_array<_Tp> | |
197c757c | 812 | { |
956a62aa JW |
813 | template<typename> |
814 | struct __untag_result | |
815 | : false_type | |
816 | { using element_type = _Tp; }; | |
817 | ||
818 | template <typename... _Args> | |
819 | struct __untag_result<const void(*)(_Args...)> | |
820 | : false_type | |
821 | { using element_type = void(*)(_Args...); }; | |
822 | ||
823 | template <typename... _Args> | |
824 | struct __untag_result<__variant_cookie(*)(_Args...)> | |
825 | : false_type | |
826 | { using element_type = void(*)(_Args...); }; | |
827 | ||
828 | template <typename... _Args> | |
829 | struct __untag_result<__variant_idx_cookie(*)(_Args...)> | |
830 | : false_type | |
831 | { using element_type = void(*)(_Args...); }; | |
832 | ||
833 | template <typename _Res, typename... _Args> | |
834 | struct __untag_result<__deduce_visit_result<_Res>(*)(_Args...)> | |
835 | : true_type | |
836 | { using element_type = _Res(*)(_Args...); }; | |
837 | ||
838 | using __result_is_deduced = __untag_result<_Tp>; | |
839 | ||
840 | constexpr const typename __untag_result<_Tp>::element_type& | |
197c757c TS |
841 | _M_access() const |
842 | { return _M_data; } | |
843 | ||
956a62aa | 844 | typename __untag_result<_Tp>::element_type _M_data; |
197c757c TS |
845 | }; |
846 | ||
9d89b73c | 847 | // Partial specialization with rank >= 1. |
669a6fdc VV |
848 | template<typename _Ret, |
849 | typename _Visitor, | |
850 | typename... _Variants, | |
851 | size_t __first, size_t... __rest> | |
852 | struct _Multi_array<_Ret(*)(_Visitor, _Variants...), __first, __rest...> | |
197c757c | 853 | { |
da97b98a VV |
854 | static constexpr size_t __index = |
855 | sizeof...(_Variants) - sizeof...(__rest) - 1; | |
9d89b73c | 856 | |
da97b98a | 857 | using _Variant = typename _Nth_type<__index, _Variants...>::type; |
9d89b73c | 858 | |
669a6fdc | 859 | static constexpr int __do_cookie = |
da97b98a | 860 | _Extra_visit_slot_needed<_Ret, _Variant>::value ? 1 : 0; |
9d89b73c | 861 | |
669a6fdc | 862 | using _Tp = _Ret(*)(_Visitor, _Variants...); |
9d89b73c | 863 | |
197c757c | 864 | template<typename... _Args> |
956a62aa | 865 | constexpr decltype(auto) |
197c757c | 866 | _M_access(size_t __first_index, _Args... __rest_indices) const |
9d89b73c JW |
867 | { |
868 | return _M_arr[__first_index + __do_cookie] | |
869 | ._M_access(__rest_indices...); | |
870 | } | |
197c757c | 871 | |
669a6fdc | 872 | _Multi_array<_Tp, __rest...> _M_arr[__first + __do_cookie]; |
197c757c TS |
873 | }; |
874 | ||
875 | // Creates a multi-dimensional vtable recursively. | |
197c757c TS |
876 | // |
877 | // For example, | |
878 | // visit([](auto, auto){}, | |
b01af236 TS |
879 | // variant<int, char>(), // typedef'ed as V1 |
880 | // variant<float, double, long double>()) // typedef'ed as V2 | |
197c757c | 881 | // will trigger instantiations of: |
956a62aa | 882 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 2, 3>, |
b01af236 | 883 | // tuple<V1&&, V2&&>, std::index_sequence<>> |
956a62aa | 884 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 3>, |
b01af236 | 885 | // tuple<V1&&, V2&&>, std::index_sequence<0>> |
956a62aa | 886 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
b01af236 | 887 | // tuple<V1&&, V2&&>, std::index_sequence<0, 0>> |
956a62aa | 888 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
b01af236 | 889 | // tuple<V1&&, V2&&>, std::index_sequence<0, 1>> |
956a62aa | 890 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
b01af236 | 891 | // tuple<V1&&, V2&&>, std::index_sequence<0, 2>> |
956a62aa | 892 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 3>, |
b01af236 | 893 | // tuple<V1&&, V2&&>, std::index_sequence<1>> |
956a62aa | 894 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
b01af236 | 895 | // tuple<V1&&, V2&&>, std::index_sequence<1, 0>> |
956a62aa | 896 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
b01af236 | 897 | // tuple<V1&&, V2&&>, std::index_sequence<1, 1>> |
956a62aa | 898 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
b01af236 | 899 | // tuple<V1&&, V2&&>, std::index_sequence<1, 2>> |
197c757c TS |
900 | // The returned multi-dimensional vtable can be fast accessed by the visitor |
901 | // using index calculation. | |
956a62aa | 902 | template<typename _Array_type, typename _Index_seq> |
197c757c TS |
903 | struct __gen_vtable_impl; |
904 | ||
9d89b73c JW |
905 | // Defines the _S_apply() member that returns a _Multi_array populated |
906 | // with function pointers that perform the visitation expressions e(m) | |
907 | // for each valid pack of indexes into the variant types _Variants. | |
908 | // | |
909 | // This partial specialization builds up the index sequences by recursively | |
910 | // calling _S_apply() on the next specialization of __gen_vtable_impl. | |
911 | // The base case of the recursion defines the actual function pointers. | |
956a62aa | 912 | template<typename _Result_type, typename _Visitor, size_t... __dimensions, |
b01af236 TS |
913 | typename... _Variants, size_t... __indices> |
914 | struct __gen_vtable_impl< | |
0f9cf7ff | 915 | _Multi_array<_Result_type (*)(_Visitor, _Variants...), __dimensions...>, |
956a62aa | 916 | std::index_sequence<__indices...>> |
197c757c | 917 | { |
b01af236 TS |
918 | using _Next = |
919 | remove_reference_t<typename _Nth_type<sizeof...(__indices), | |
920 | _Variants...>::type>; | |
921 | using _Array_type = | |
0f9cf7ff TS |
922 | _Multi_array<_Result_type (*)(_Visitor, _Variants...), |
923 | __dimensions...>; | |
b01af236 | 924 | |
197c757c TS |
925 | static constexpr _Array_type |
926 | _S_apply() | |
927 | { | |
928 | _Array_type __vtable{}; | |
929 | _S_apply_all_alts( | |
b01af236 | 930 | __vtable, make_index_sequence<variant_size_v<_Next>>()); |
197c757c TS |
931 | return __vtable; |
932 | } | |
933 | ||
b01af236 | 934 | template<size_t... __var_indices> |
197c757c | 935 | static constexpr void |
b01af236 TS |
936 | _S_apply_all_alts(_Array_type& __vtable, |
937 | std::index_sequence<__var_indices...>) | |
938 | { | |
da97b98a | 939 | if constexpr (_Extra_visit_slot_needed<_Result_type, _Next>::value) |
669a6fdc VV |
940 | (_S_apply_single_alt<true, __var_indices>( |
941 | __vtable._M_arr[__var_indices + 1], | |
942 | &(__vtable._M_arr[0])), ...); | |
943 | else | |
944 | (_S_apply_single_alt<false, __var_indices>( | |
945 | __vtable._M_arr[__var_indices]), ...); | |
b01af236 | 946 | } |
197c757c | 947 | |
669a6fdc | 948 | template<bool __do_cookie, size_t __index, typename _Tp> |
197c757c | 949 | static constexpr void |
669a6fdc | 950 | _S_apply_single_alt(_Tp& __element, _Tp* __cookie_element = nullptr) |
197c757c | 951 | { |
669a6fdc VV |
952 | if constexpr (__do_cookie) |
953 | { | |
954 | __element = __gen_vtable_impl< | |
955 | _Tp, | |
669a6fdc VV |
956 | std::index_sequence<__indices..., __index>>::_S_apply(); |
957 | *__cookie_element = __gen_vtable_impl< | |
958 | _Tp, | |
669a6fdc VV |
959 | std::index_sequence<__indices..., variant_npos>>::_S_apply(); |
960 | } | |
961 | else | |
962 | { | |
1f65bf2a | 963 | auto __tmp_element = __gen_vtable_impl< |
956a62aa | 964 | remove_reference_t<decltype(__element)>, |
669a6fdc | 965 | std::index_sequence<__indices..., __index>>::_S_apply(); |
1f65bf2a VV |
966 | static_assert(is_same_v<_Tp, decltype(__tmp_element)>, |
967 | "std::visit requires the visitor to have the same " | |
968 | "return type for all alternatives of a variant"); | |
969 | __element = __tmp_element; | |
669a6fdc | 970 | } |
197c757c TS |
971 | } |
972 | }; | |
973 | ||
9d89b73c JW |
974 | // This partial specialization is the base case for the recursion. |
975 | // It populates a _Multi_array element with the address of a function | |
976 | // that invokes the visitor with the alternatives specified by __indices. | |
956a62aa | 977 | template<typename _Result_type, typename _Visitor, typename... _Variants, |
b01af236 | 978 | size_t... __indices> |
197c757c | 979 | struct __gen_vtable_impl< |
b01af236 | 980 | _Multi_array<_Result_type (*)(_Visitor, _Variants...)>, |
956a62aa | 981 | std::index_sequence<__indices...>> |
197c757c TS |
982 | { |
983 | using _Array_type = | |
9d89b73c | 984 | _Multi_array<_Result_type (*)(_Visitor, _Variants...)>; |
b01af236 | 985 | |
669a6fdc VV |
986 | template<size_t __index, typename _Variant> |
987 | static constexpr decltype(auto) | |
be46043e | 988 | __element_by_index_or_cookie(_Variant&& __var) noexcept |
669a6fdc VV |
989 | { |
990 | if constexpr (__index != variant_npos) | |
991 | return __variant::__get<__index>(std::forward<_Variant>(__var)); | |
992 | else | |
993 | return __variant_cookie{}; | |
994 | } | |
995 | ||
469218a3 | 996 | static constexpr decltype(auto) |
956a62aa | 997 | __visit_invoke(_Visitor&& __visitor, _Variants... __vars) |
b01af236 | 998 | { |
9d89b73c | 999 | if constexpr (is_same_v<_Result_type, __variant_idx_cookie>) |
956a62aa JW |
1000 | // For raw visitation using indices, pass the indices to the visitor |
1001 | // and discard the return value: | |
1002 | std::__invoke(std::forward<_Visitor>(__visitor), | |
9d89b73c JW |
1003 | __element_by_index_or_cookie<__indices>( |
1004 | std::forward<_Variants>(__vars))..., | |
1005 | integral_constant<size_t, __indices>()...); | |
956a62aa JW |
1006 | else if constexpr (is_same_v<_Result_type, __variant_cookie>) |
1007 | // For raw visitation without indices, and discard the return value: | |
1008 | std::__invoke(std::forward<_Visitor>(__visitor), | |
9d89b73c JW |
1009 | __element_by_index_or_cookie<__indices>( |
1010 | std::forward<_Variants>(__vars))...); | |
956a62aa JW |
1011 | else if constexpr (_Array_type::__result_is_deduced::value) |
1012 | // For the usual std::visit case deduce the return value: | |
f1ba6c5a | 1013 | return std::__invoke(std::forward<_Visitor>(__visitor), |
9d89b73c JW |
1014 | __element_by_index_or_cookie<__indices>( |
1015 | std::forward<_Variants>(__vars))...); | |
956a62aa JW |
1016 | else // for std::visit<R> use INVOKE<R> |
1017 | return std::__invoke_r<_Result_type>( | |
1018 | std::forward<_Visitor>(__visitor), | |
1019 | __variant::__get<__indices>(std::forward<_Variants>(__vars))...); | |
3d01c7c2 VV |
1020 | } |
1021 | ||
197c757c TS |
1022 | static constexpr auto |
1023 | _S_apply() | |
3427e313 VV |
1024 | { |
1025 | if constexpr (_Array_type::__result_is_deduced::value) | |
1026 | { | |
1027 | constexpr bool __visit_ret_type_mismatch = | |
1028 | !is_same_v<typename _Result_type::type, | |
1029 | decltype(__visit_invoke(std::declval<_Visitor>(), | |
1030 | std::declval<_Variants>()...))>; | |
1031 | if constexpr (__visit_ret_type_mismatch) | |
1032 | { | |
1f65bf2a VV |
1033 | struct __cannot_match {}; |
1034 | return __cannot_match{}; | |
3427e313 VV |
1035 | } |
1036 | else | |
1037 | return _Array_type{&__visit_invoke}; | |
1038 | } | |
1039 | else | |
1040 | return _Array_type{&__visit_invoke}; | |
1041 | } | |
197c757c TS |
1042 | }; |
1043 | ||
956a62aa | 1044 | template<typename _Result_type, typename _Visitor, typename... _Variants> |
197c757c TS |
1045 | struct __gen_vtable |
1046 | { | |
197c757c | 1047 | using _Array_type = |
9d89b73c | 1048 | _Multi_array<_Result_type (*)(_Visitor, _Variants...), |
11767f80 | 1049 | variant_size_v<remove_reference_t<_Variants>>...>; |
197c757c | 1050 | |
9d89b73c | 1051 | static constexpr _Array_type _S_vtable |
956a62aa | 1052 | = __gen_vtable_impl<_Array_type, std::index_sequence<>>::_S_apply(); |
197c757c TS |
1053 | }; |
1054 | ||
458ef690 TS |
1055 | template<size_t _Np, typename _Tp> |
1056 | struct _Base_dedup : public _Tp { }; | |
1057 | ||
1058 | template<typename _Variant, typename __indices> | |
1059 | struct _Variant_hash_base; | |
1060 | ||
1061 | template<typename... _Types, size_t... __indices> | |
1062 | struct _Variant_hash_base<variant<_Types...>, | |
1063 | std::index_sequence<__indices...>> | |
1064 | : _Base_dedup<__indices, __poison_hash<remove_const_t<_Types>>>... { }; | |
1065 | ||
197c757c TS |
1066 | } // namespace __variant |
1067 | } // namespace __detail | |
1068 | ||
669a6fdc VV |
1069 | template<size_t _Np, typename _Variant, typename... _Args> |
1070 | void __variant_construct_by_index(_Variant& __v, _Args&&... __args) | |
1071 | { | |
1072 | __v._M_index = _Np; | |
1073 | auto&& __storage = __detail::__variant::__get<_Np>(__v); | |
1074 | ::new ((void*)std::addressof(__storage)) | |
1075 | remove_reference_t<decltype(__storage)> | |
1076 | (std::forward<_Args>(__args)...); | |
1077 | } | |
1078 | ||
197c757c | 1079 | template<typename _Tp, typename... _Types> |
469218a3 JW |
1080 | constexpr bool |
1081 | holds_alternative(const variant<_Types...>& __v) noexcept | |
197c757c TS |
1082 | { |
1083 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
c43c3af2 | 1084 | "T must occur exactly once in alternatives"); |
197c757c TS |
1085 | return __v.index() == __detail::__variant::__index_of_v<_Tp, _Types...>; |
1086 | } | |
1087 | ||
197c757c | 1088 | template<typename _Tp, typename... _Types> |
469218a3 | 1089 | constexpr _Tp& get(variant<_Types...>& __v) |
197c757c TS |
1090 | { |
1091 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
c43c3af2 | 1092 | "T must occur exactly once in alternatives"); |
801b2266 | 1093 | static_assert(!is_void_v<_Tp>, "_Tp must not be void"); |
5dbbf899 | 1094 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v); |
197c757c TS |
1095 | } |
1096 | ||
1097 | template<typename _Tp, typename... _Types> | |
469218a3 | 1098 | constexpr _Tp&& get(variant<_Types...>&& __v) |
197c757c TS |
1099 | { |
1100 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
c43c3af2 | 1101 | "T must occur exactly once in alternatives"); |
801b2266 | 1102 | static_assert(!is_void_v<_Tp>, "_Tp must not be void"); |
5dbbf899 | 1103 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>( |
197c757c TS |
1104 | std::move(__v)); |
1105 | } | |
1106 | ||
1107 | template<typename _Tp, typename... _Types> | |
469218a3 | 1108 | constexpr const _Tp& get(const variant<_Types...>& __v) |
197c757c TS |
1109 | { |
1110 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
c43c3af2 | 1111 | "T must occur exactly once in alternatives"); |
801b2266 | 1112 | static_assert(!is_void_v<_Tp>, "_Tp must not be void"); |
5dbbf899 | 1113 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v); |
197c757c TS |
1114 | } |
1115 | ||
1116 | template<typename _Tp, typename... _Types> | |
469218a3 | 1117 | constexpr const _Tp&& get(const variant<_Types...>&& __v) |
197c757c TS |
1118 | { |
1119 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
c43c3af2 | 1120 | "T must occur exactly once in alternatives"); |
801b2266 | 1121 | static_assert(!is_void_v<_Tp>, "_Tp must not be void"); |
5dbbf899 | 1122 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>( |
197c757c TS |
1123 | std::move(__v)); |
1124 | } | |
1125 | ||
1126 | template<size_t _Np, typename... _Types> | |
469218a3 | 1127 | constexpr add_pointer_t<variant_alternative_t<_Np, variant<_Types...>>> |
197c757c TS |
1128 | get_if(variant<_Types...>* __ptr) noexcept |
1129 | { | |
1130 | using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>; | |
1131 | static_assert(_Np < sizeof...(_Types), | |
801b2266 JW |
1132 | "The index must be in [0, number of alternatives)"); |
1133 | static_assert(!is_void_v<_Alternative_type>, "_Tp must not be void"); | |
197c757c | 1134 | if (__ptr && __ptr->index() == _Np) |
669a6fdc | 1135 | return std::addressof(__detail::__variant::__get<_Np>(*__ptr)); |
197c757c TS |
1136 | return nullptr; |
1137 | } | |
1138 | ||
1139 | template<size_t _Np, typename... _Types> | |
469218a3 | 1140 | constexpr |
9189f559 | 1141 | add_pointer_t<const variant_alternative_t<_Np, variant<_Types...>>> |
197c757c TS |
1142 | get_if(const variant<_Types...>* __ptr) noexcept |
1143 | { | |
1144 | using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>; | |
1145 | static_assert(_Np < sizeof...(_Types), | |
801b2266 JW |
1146 | "The index must be in [0, number of alternatives)"); |
1147 | static_assert(!is_void_v<_Alternative_type>, "_Tp must not be void"); | |
197c757c | 1148 | if (__ptr && __ptr->index() == _Np) |
669a6fdc | 1149 | return std::addressof(__detail::__variant::__get<_Np>(*__ptr)); |
197c757c TS |
1150 | return nullptr; |
1151 | } | |
1152 | ||
1153 | template<typename _Tp, typename... _Types> | |
469218a3 | 1154 | constexpr add_pointer_t<_Tp> |
9189f559 | 1155 | get_if(variant<_Types...>* __ptr) noexcept |
197c757c TS |
1156 | { |
1157 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
c43c3af2 | 1158 | "T must occur exactly once in alternatives"); |
801b2266 | 1159 | static_assert(!is_void_v<_Tp>, "_Tp must not be void"); |
5dbbf899 JW |
1160 | return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>( |
1161 | __ptr); | |
197c757c TS |
1162 | } |
1163 | ||
1164 | template<typename _Tp, typename... _Types> | |
469218a3 | 1165 | constexpr add_pointer_t<const _Tp> |
be46043e | 1166 | get_if(const variant<_Types...>* __ptr) noexcept |
197c757c TS |
1167 | { |
1168 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
c43c3af2 | 1169 | "T must occur exactly once in alternatives"); |
801b2266 | 1170 | static_assert(!is_void_v<_Tp>, "_Tp must not be void"); |
5dbbf899 JW |
1171 | return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>( |
1172 | __ptr); | |
197c757c TS |
1173 | } |
1174 | ||
d255829b | 1175 | struct monostate { }; |
197c757c | 1176 | |
d255829b TS |
1177 | #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP, __NAME) \ |
1178 | template<typename... _Types> \ | |
1179 | constexpr bool operator __OP(const variant<_Types...>& __lhs, \ | |
1180 | const variant<_Types...>& __rhs) \ | |
1181 | { \ | |
669a6fdc | 1182 | bool __ret = true; \ |
956a62aa JW |
1183 | __detail::__variant::__raw_idx_visit( \ |
1184 | [&__ret, &__lhs] (auto&& __rhs_mem, auto __rhs_index) mutable \ | |
669a6fdc | 1185 | { \ |
f1ba6c5a VV |
1186 | if constexpr (__rhs_index != variant_npos) \ |
1187 | { \ | |
1188 | if (__lhs.index() == __rhs_index) \ | |
1189 | { \ | |
1190 | auto& __this_mem = std::get<__rhs_index>(__lhs); \ | |
1191 | __ret = __this_mem __OP __rhs_mem; \ | |
1192 | } \ | |
1193 | else \ | |
1194 | __ret = (__lhs.index() + 1) __OP (__rhs_index + 1); \ | |
1195 | } \ | |
1196 | else \ | |
1197 | __ret = (__lhs.index() + 1) __OP (__rhs_index + 1); \ | |
f1ba6c5a | 1198 | }, __rhs); \ |
669a6fdc | 1199 | return __ret; \ |
9e589880 | 1200 | } |
d255829b TS |
1201 | |
1202 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<, less) | |
1203 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<=, less_equal) | |
1204 | _VARIANT_RELATION_FUNCTION_TEMPLATE(==, equal) | |
1205 | _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal) | |
1206 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>=, greater_equal) | |
1207 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>, greater) | |
1208 | ||
1209 | #undef _VARIANT_RELATION_FUNCTION_TEMPLATE | |
197c757c | 1210 | |
9e589880 JW |
1211 | constexpr bool operator==(monostate, monostate) noexcept { return true; } |
1212 | ||
1213 | #ifdef __cpp_lib_three_way_comparison | |
1214 | template<typename... _Types> | |
1215 | requires (three_way_comparable<_Types> && ...) | |
1216 | constexpr | |
1217 | common_comparison_category_t<compare_three_way_result_t<_Types>...> | |
1218 | operator<=>(const variant<_Types...>& __v, const variant<_Types...>& __w) | |
1219 | { | |
1220 | common_comparison_category_t<compare_three_way_result_t<_Types>...> __ret | |
1221 | = strong_ordering::equal; | |
1222 | ||
1223 | __detail::__variant::__raw_idx_visit( | |
1224 | [&__ret, &__v] (auto&& __w_mem, auto __w_index) mutable | |
1225 | { | |
1226 | if constexpr (__w_index != variant_npos) | |
1227 | { | |
1228 | if (__v.index() == __w_index) | |
1229 | { | |
1230 | auto& __this_mem = std::get<__w_index>(__v); | |
1231 | __ret = __this_mem <=> __w_mem; | |
1232 | return; | |
1233 | } | |
1234 | } | |
1235 | __ret = (__v.index() + 1) <=> (__w_index + 1); | |
1236 | }, __w); | |
1237 | return __ret; | |
1238 | } | |
1239 | ||
1240 | constexpr strong_ordering | |
1241 | operator<=>(monostate, monostate) noexcept { return strong_ordering::equal; } | |
1242 | #else | |
1243 | constexpr bool operator!=(monostate, monostate) noexcept { return false; } | |
1244 | constexpr bool operator<(monostate, monostate) noexcept { return false; } | |
1245 | constexpr bool operator>(monostate, monostate) noexcept { return false; } | |
1246 | constexpr bool operator<=(monostate, monostate) noexcept { return true; } | |
1247 | constexpr bool operator>=(monostate, monostate) noexcept { return true; } | |
1248 | #endif | |
1249 | ||
197c757c | 1250 | template<typename _Visitor, typename... _Variants> |
b01af236 | 1251 | constexpr decltype(auto) visit(_Visitor&&, _Variants&&...); |
197c757c | 1252 | |
197c757c | 1253 | template<typename... _Types> |
458ef690 TS |
1254 | inline enable_if_t<(is_move_constructible_v<_Types> && ...) |
1255 | && (is_swappable_v<_Types> && ...)> | |
a2863bde VV |
1256 | swap(variant<_Types...>& __lhs, variant<_Types...>& __rhs) |
1257 | noexcept(noexcept(__lhs.swap(__rhs))) | |
197c757c TS |
1258 | { __lhs.swap(__rhs); } |
1259 | ||
a2863bde | 1260 | template<typename... _Types> |
258ee761 BA |
1261 | enable_if_t<!((is_move_constructible_v<_Types> && ...) |
1262 | && (is_swappable_v<_Types> && ...))> | |
a2863bde VV |
1263 | swap(variant<_Types...>&, variant<_Types...>&) = delete; |
1264 | ||
197c757c TS |
1265 | class bad_variant_access : public exception |
1266 | { | |
1267 | public: | |
c43c3af2 JW |
1268 | bad_variant_access() noexcept { } |
1269 | ||
197c757c TS |
1270 | const char* what() const noexcept override |
1271 | { return _M_reason; } | |
1272 | ||
1273 | private: | |
c43c3af2 | 1274 | bad_variant_access(const char* __reason) noexcept : _M_reason(__reason) { } |
197c757c | 1275 | |
c43c3af2 JW |
1276 | // Must point to a string with static storage duration: |
1277 | const char* _M_reason = "bad variant access"; | |
197c757c TS |
1278 | |
1279 | friend void __throw_bad_variant_access(const char* __what); | |
1280 | }; | |
1281 | ||
c43c3af2 | 1282 | // Must only be called with a string literal |
197c757c TS |
1283 | inline void |
1284 | __throw_bad_variant_access(const char* __what) | |
1285 | { _GLIBCXX_THROW_OR_ABORT(bad_variant_access(__what)); } | |
1286 | ||
c43c3af2 JW |
1287 | inline void |
1288 | __throw_bad_variant_access(bool __valueless) | |
1289 | { | |
1290 | if (__valueless) [[__unlikely__]] | |
1291 | __throw_bad_variant_access("std::get: variant is valueless"); | |
1292 | else | |
1293 | __throw_bad_variant_access("std::get: wrong index for variant"); | |
1294 | } | |
1295 | ||
197c757c TS |
1296 | template<typename... _Types> |
1297 | class variant | |
1298 | : private __detail::__variant::_Variant_base<_Types...>, | |
1299 | private _Enable_default_constructor< | |
4a15d842 | 1300 | __detail::__variant::_Traits<_Types...>::_S_default_ctor, |
70503724 | 1301 | variant<_Types...>>, |
197c757c | 1302 | private _Enable_copy_move< |
4a15d842 FD |
1303 | __detail::__variant::_Traits<_Types...>::_S_copy_ctor, |
1304 | __detail::__variant::_Traits<_Types...>::_S_copy_assign, | |
1305 | __detail::__variant::_Traits<_Types...>::_S_move_ctor, | |
1306 | __detail::__variant::_Traits<_Types...>::_S_move_assign, | |
197c757c TS |
1307 | variant<_Types...>> |
1308 | { | |
1309 | private: | |
669a6fdc VV |
1310 | template <typename... _UTypes, typename _Tp> |
1311 | friend decltype(auto) __variant_cast(_Tp&&); | |
1312 | template<size_t _Np, typename _Variant, typename... _Args> | |
1313 | friend void __variant_construct_by_index(_Variant& __v, | |
1314 | _Args&&... __args); | |
1315 | ||
7b277e8b TS |
1316 | static_assert(sizeof...(_Types) > 0, |
1317 | "variant must have at least one alternative"); | |
1318 | static_assert(!(std::is_reference_v<_Types> || ...), | |
1319 | "variant must have no reference alternative"); | |
1320 | static_assert(!(std::is_void_v<_Types> || ...), | |
1321 | "variant must have no void alternative"); | |
1322 | ||
197c757c TS |
1323 | using _Base = __detail::__variant::_Variant_base<_Types...>; |
1324 | using _Default_ctor_enabler = | |
4a15d842 FD |
1325 | _Enable_default_constructor< |
1326 | __detail::__variant::_Traits<_Types...>::_S_default_ctor, | |
1327 | variant<_Types...>>; | |
197c757c | 1328 | |
06715e1c JW |
1329 | template<typename _Tp> |
1330 | static constexpr bool __not_self | |
1331 | = !is_same_v<__remove_cvref_t<_Tp>, variant>; | |
1332 | ||
197c757c TS |
1333 | template<typename _Tp> |
1334 | static constexpr bool | |
1335 | __exactly_once = __detail::__variant::__exactly_once<_Tp, _Types...>; | |
1336 | ||
1337 | template<typename _Tp> | |
d069df01 JW |
1338 | static constexpr size_t __accepted_index |
1339 | = __detail::__variant::__accepted_index<_Tp, variant>::value; | |
197c757c | 1340 | |
06715e1c JW |
1341 | template<size_t _Np, typename = enable_if_t<(_Np < sizeof...(_Types))>> |
1342 | using __to_type = variant_alternative_t<_Np, variant>; | |
197c757c | 1343 | |
06715e1c | 1344 | template<typename _Tp, typename = enable_if_t<__not_self<_Tp>>> |
197c757c TS |
1345 | using __accepted_type = __to_type<__accepted_index<_Tp>>; |
1346 | ||
197c757c TS |
1347 | template<typename _Tp> |
1348 | static constexpr size_t __index_of = | |
1349 | __detail::__variant::__index_of_v<_Tp, _Types...>; | |
1350 | ||
70503724 TS |
1351 | using _Traits = __detail::__variant::_Traits<_Types...>; |
1352 | ||
06715e1c JW |
1353 | template<typename _Tp> |
1354 | struct __is_in_place_tag : false_type { }; | |
1355 | template<typename _Tp> | |
1356 | struct __is_in_place_tag<in_place_type_t<_Tp>> : true_type { }; | |
1357 | template<size_t _Np> | |
1358 | struct __is_in_place_tag<in_place_index_t<_Np>> : true_type { }; | |
1359 | ||
1360 | template<typename _Tp> | |
1361 | static constexpr bool __not_in_place_tag | |
1362 | = !__is_in_place_tag<__remove_cvref_t<_Tp>>::value; | |
1363 | ||
197c757c | 1364 | public: |
70503724 TS |
1365 | variant() = default; |
1366 | variant(const variant& __rhs) = default; | |
1367 | variant(variant&&) = default; | |
1368 | variant& operator=(const variant&) = default; | |
1369 | variant& operator=(variant&&) = default; | |
1370 | ~variant() = default; | |
197c757c TS |
1371 | |
1372 | template<typename _Tp, | |
06715e1c JW |
1373 | typename = enable_if_t<sizeof...(_Types) != 0>, |
1374 | typename = enable_if_t<__not_in_place_tag<_Tp>>, | |
1375 | typename _Tj = __accepted_type<_Tp&&>, | |
1376 | typename = enable_if_t<__exactly_once<_Tj> | |
1377 | && is_constructible_v<_Tj, _Tp>>> | |
197c757c TS |
1378 | constexpr |
1379 | variant(_Tp&& __t) | |
06715e1c | 1380 | noexcept(is_nothrow_constructible_v<_Tj, _Tp>) |
d069df01 | 1381 | : variant(in_place_index<__accepted_index<_Tp>>, |
4a15d842 | 1382 | std::forward<_Tp>(__t)) |
59e36c85 | 1383 | { } |
197c757c TS |
1384 | |
1385 | template<typename _Tp, typename... _Args, | |
1386 | typename = enable_if_t<__exactly_once<_Tp> | |
06715e1c | 1387 | && is_constructible_v<_Tp, _Args...>>> |
197c757c TS |
1388 | constexpr explicit |
1389 | variant(in_place_type_t<_Tp>, _Args&&... __args) | |
70503724 | 1390 | : variant(in_place_index<__index_of<_Tp>>, |
4a15d842 | 1391 | std::forward<_Args>(__args)...) |
59e36c85 | 1392 | { } |
197c757c TS |
1393 | |
1394 | template<typename _Tp, typename _Up, typename... _Args, | |
1395 | typename = enable_if_t<__exactly_once<_Tp> | |
06715e1c JW |
1396 | && is_constructible_v<_Tp, |
1397 | initializer_list<_Up>&, _Args...>>> | |
197c757c TS |
1398 | constexpr explicit |
1399 | variant(in_place_type_t<_Tp>, initializer_list<_Up> __il, | |
1400 | _Args&&... __args) | |
627a2f59 | 1401 | : variant(in_place_index<__index_of<_Tp>>, __il, |
64626fca | 1402 | std::forward<_Args>(__args)...) |
59e36c85 | 1403 | { } |
197c757c TS |
1404 | |
1405 | template<size_t _Np, typename... _Args, | |
06715e1c JW |
1406 | typename _Tp = __to_type<_Np>, |
1407 | typename = enable_if_t<is_constructible_v<_Tp, _Args...>>> | |
197c757c TS |
1408 | constexpr explicit |
1409 | variant(in_place_index_t<_Np>, _Args&&... __args) | |
627a2f59 | 1410 | : _Base(in_place_index<_Np>, std::forward<_Args>(__args)...), |
197c757c | 1411 | _Default_ctor_enabler(_Enable_default_constructor_tag{}) |
59e36c85 | 1412 | { } |
197c757c TS |
1413 | |
1414 | template<size_t _Np, typename _Up, typename... _Args, | |
06715e1c JW |
1415 | typename _Tp = __to_type<_Np>, |
1416 | typename = enable_if_t<is_constructible_v<_Tp, | |
1417 | initializer_list<_Up>&, | |
1418 | _Args...>>> | |
197c757c TS |
1419 | constexpr explicit |
1420 | variant(in_place_index_t<_Np>, initializer_list<_Up> __il, | |
1421 | _Args&&... __args) | |
627a2f59 | 1422 | : _Base(in_place_index<_Np>, __il, std::forward<_Args>(__args)...), |
197c757c | 1423 | _Default_ctor_enabler(_Enable_default_constructor_tag{}) |
59e36c85 | 1424 | { } |
197c757c | 1425 | |
197c757c TS |
1426 | template<typename _Tp> |
1427 | enable_if_t<__exactly_once<__accepted_type<_Tp&&>> | |
06715e1c JW |
1428 | && is_constructible_v<__accepted_type<_Tp&&>, _Tp> |
1429 | && is_assignable_v<__accepted_type<_Tp&&>&, _Tp>, | |
1430 | variant&> | |
197c757c | 1431 | operator=(_Tp&& __rhs) |
06715e1c JW |
1432 | noexcept(is_nothrow_assignable_v<__accepted_type<_Tp&&>&, _Tp> |
1433 | && is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp>) | |
197c757c | 1434 | { |
d069df01 | 1435 | constexpr auto __index = __accepted_index<_Tp>; |
197c757c | 1436 | if (index() == __index) |
c42bc5d7 | 1437 | std::get<__index>(*this) = std::forward<_Tp>(__rhs); |
197c757c | 1438 | else |
86a57ce1 JW |
1439 | { |
1440 | using _Tj = __accepted_type<_Tp&&>; | |
1441 | if constexpr (is_nothrow_constructible_v<_Tj, _Tp> | |
1442 | || !is_nothrow_move_constructible_v<_Tj>) | |
1443 | this->emplace<__index>(std::forward<_Tp>(__rhs)); | |
1444 | else | |
1445 | operator=(variant(std::forward<_Tp>(__rhs))); | |
1446 | } | |
197c757c TS |
1447 | return *this; |
1448 | } | |
1449 | ||
1450 | template<typename _Tp, typename... _Args> | |
df990182 VV |
1451 | enable_if_t<is_constructible_v<_Tp, _Args...> && __exactly_once<_Tp>, |
1452 | _Tp&> | |
458ef690 | 1453 | emplace(_Args&&... __args) |
197c757c | 1454 | { |
59e36c85 JW |
1455 | constexpr size_t __index = __index_of<_Tp>; |
1456 | return this->emplace<__index>(std::forward<_Args>(__args)...); | |
197c757c TS |
1457 | } |
1458 | ||
1459 | template<typename _Tp, typename _Up, typename... _Args> | |
458ef690 | 1460 | enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...> |
df990182 VV |
1461 | && __exactly_once<_Tp>, |
1462 | _Tp&> | |
458ef690 | 1463 | emplace(initializer_list<_Up> __il, _Args&&... __args) |
197c757c | 1464 | { |
59e36c85 JW |
1465 | constexpr size_t __index = __index_of<_Tp>; |
1466 | return this->emplace<__index>(__il, std::forward<_Args>(__args)...); | |
197c757c TS |
1467 | } |
1468 | ||
1469 | template<size_t _Np, typename... _Args> | |
458ef690 | 1470 | enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>, |
df990182 VV |
1471 | _Args...>, |
1472 | variant_alternative_t<_Np, variant>&> | |
458ef690 | 1473 | emplace(_Args&&... __args) |
197c757c TS |
1474 | { |
1475 | static_assert(_Np < sizeof...(_Types), | |
801b2266 | 1476 | "The index must be in [0, number of alternatives)"); |
caf80d87 | 1477 | using type = variant_alternative_t<_Np, variant>; |
10f26de9 JW |
1478 | // Provide the strong exception-safety guarantee when possible, |
1479 | // to avoid becoming valueless. | |
1480 | if constexpr (is_nothrow_constructible_v<type, _Args...>) | |
1481 | { | |
1482 | this->_M_reset(); | |
1483 | __variant_construct_by_index<_Np>(*this, | |
1484 | std::forward<_Args>(__args)...); | |
1485 | } | |
1486 | else if constexpr (is_scalar_v<type>) | |
caf80d87 | 1487 | { |
10f26de9 JW |
1488 | // This might invoke a potentially-throwing conversion operator: |
1489 | const type __tmp(std::forward<_Args>(__args)...); | |
1490 | // But these steps won't throw: | |
1491 | this->_M_reset(); | |
1492 | __variant_construct_by_index<_Np>(*this, __tmp); | |
1493 | } | |
47a468bd JW |
1494 | else if constexpr (__detail::__variant::_Never_valueless_alt<type>() |
1495 | && _Traits::_S_move_assign) | |
10f26de9 JW |
1496 | { |
1497 | // This construction might throw: | |
caf80d87 JW |
1498 | variant __tmp(in_place_index<_Np>, |
1499 | std::forward<_Args>(__args)...); | |
10f26de9 | 1500 | // But _Never_valueless_alt<type> means this won't: |
caf80d87 | 1501 | *this = std::move(__tmp); |
197c757c | 1502 | } |
10f26de9 | 1503 | else |
197c757c | 1504 | { |
10f26de9 JW |
1505 | // This case only provides the basic exception-safety guarantee, |
1506 | // i.e. the variant can become valueless. | |
1507 | this->_M_reset(); | |
1508 | __try | |
1509 | { | |
1510 | __variant_construct_by_index<_Np>(*this, | |
1511 | std::forward<_Args>(__args)...); | |
1512 | } | |
1513 | __catch (...) | |
1514 | { | |
d7aa21a3 JW |
1515 | using __index_type = decltype(this->_M_index); |
1516 | this->_M_index = static_cast<__index_type>(variant_npos); | |
10f26de9 JW |
1517 | __throw_exception_again; |
1518 | } | |
197c757c | 1519 | } |
df990182 | 1520 | return std::get<_Np>(*this); |
197c757c TS |
1521 | } |
1522 | ||
1523 | template<size_t _Np, typename _Up, typename... _Args> | |
458ef690 | 1524 | enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>, |
df990182 VV |
1525 | initializer_list<_Up>&, _Args...>, |
1526 | variant_alternative_t<_Np, variant>&> | |
458ef690 | 1527 | emplace(initializer_list<_Up> __il, _Args&&... __args) |
197c757c TS |
1528 | { |
1529 | static_assert(_Np < sizeof...(_Types), | |
801b2266 | 1530 | "The index must be in [0, number of alternatives)"); |
caf80d87 | 1531 | using type = variant_alternative_t<_Np, variant>; |
10f26de9 JW |
1532 | // Provide the strong exception-safety guarantee when possible, |
1533 | // to avoid becoming valueless. | |
1534 | if constexpr (is_nothrow_constructible_v<type, | |
1535 | initializer_list<_Up>&, | |
1536 | _Args...>) | |
caf80d87 | 1537 | { |
10f26de9 JW |
1538 | this->_M_reset(); |
1539 | __variant_construct_by_index<_Np>(*this, __il, | |
1540 | std::forward<_Args>(__args)...); | |
1541 | } | |
47a468bd JW |
1542 | else if constexpr (__detail::__variant::_Never_valueless_alt<type>() |
1543 | && _Traits::_S_move_assign) | |
10f26de9 JW |
1544 | { |
1545 | // This construction might throw: | |
caf80d87 JW |
1546 | variant __tmp(in_place_index<_Np>, __il, |
1547 | std::forward<_Args>(__args)...); | |
10f26de9 | 1548 | // But _Never_valueless_alt<type> means this won't: |
caf80d87 | 1549 | *this = std::move(__tmp); |
197c757c | 1550 | } |
10f26de9 | 1551 | else |
197c757c | 1552 | { |
10f26de9 JW |
1553 | // This case only provides the basic exception-safety guarantee, |
1554 | // i.e. the variant can become valueless. | |
1555 | this->_M_reset(); | |
1556 | __try | |
1557 | { | |
1558 | __variant_construct_by_index<_Np>(*this, __il, | |
1559 | std::forward<_Args>(__args)...); | |
1560 | } | |
1561 | __catch (...) | |
1562 | { | |
d7aa21a3 JW |
1563 | using __index_type = decltype(this->_M_index); |
1564 | this->_M_index = static_cast<__index_type>(variant_npos); | |
10f26de9 JW |
1565 | __throw_exception_again; |
1566 | } | |
197c757c | 1567 | } |
df990182 | 1568 | return std::get<_Np>(*this); |
197c757c TS |
1569 | } |
1570 | ||
1571 | constexpr bool valueless_by_exception() const noexcept | |
1572 | { return !this->_M_valid(); } | |
1573 | ||
1574 | constexpr size_t index() const noexcept | |
1e8822d3 JW |
1575 | { |
1576 | using __index_type = typename _Base::__index_type; | |
fe69bee3 | 1577 | if constexpr (__detail::__variant::__never_valueless<_Types...>()) |
1e8822d3 JW |
1578 | return this->_M_index; |
1579 | else if constexpr (sizeof...(_Types) <= __index_type(-1) / 2) | |
1580 | return make_signed_t<__index_type>(this->_M_index); | |
1581 | else | |
1582 | return size_t(__index_type(this->_M_index + 1)) - 1; | |
1583 | } | |
197c757c TS |
1584 | |
1585 | void | |
1586 | swap(variant& __rhs) | |
258ee761 | 1587 | noexcept((__is_nothrow_swappable<_Types>::value && ...) |
458ef690 | 1588 | && is_nothrow_move_constructible_v<variant>) |
197c757c | 1589 | { |
956a62aa JW |
1590 | __detail::__variant::__raw_idx_visit( |
1591 | [this, &__rhs](auto&& __rhs_mem, auto __rhs_index) mutable | |
197c757c | 1592 | { |
f1ba6c5a | 1593 | if constexpr (__rhs_index != variant_npos) |
197c757c | 1594 | { |
f1ba6c5a | 1595 | if (this->index() == __rhs_index) |
669a6fdc | 1596 | { |
f1ba6c5a VV |
1597 | auto& __this_mem = |
1598 | std::get<__rhs_index>(*this); | |
669a6fdc VV |
1599 | using std::swap; |
1600 | swap(__this_mem, __rhs_mem); | |
1601 | } | |
f1ba6c5a VV |
1602 | else |
1603 | { | |
b62dcd16 | 1604 | if (!this->valueless_by_exception()) [[__likely__]] |
f1ba6c5a VV |
1605 | { |
1606 | auto __tmp(std::move(__rhs_mem)); | |
1607 | __rhs = std::move(*this); | |
1608 | this->_M_destructive_move(__rhs_index, | |
1609 | std::move(__tmp)); | |
1610 | } | |
1611 | else | |
1612 | { | |
1613 | this->_M_destructive_move(__rhs_index, | |
1614 | std::move(__rhs_mem)); | |
1615 | __rhs._M_reset(); | |
1616 | } | |
1617 | } | |
197c757c | 1618 | } |
669a6fdc VV |
1619 | else |
1620 | { | |
b62dcd16 | 1621 | if (!this->valueless_by_exception()) [[__likely__]] |
669a6fdc | 1622 | { |
f1ba6c5a | 1623 | __rhs = std::move(*this); |
669a6fdc VV |
1624 | this->_M_reset(); |
1625 | } | |
669a6fdc | 1626 | } |
f1ba6c5a | 1627 | }, __rhs); |
197c757c TS |
1628 | } |
1629 | ||
9189f559 | 1630 | private: |
9189f559 | 1631 | |
08233f0d | 1632 | #if defined(__clang__) && __clang_major__ <= 7 |
aafaa325 JW |
1633 | public: |
1634 | using _Base::_M_u; // See https://bugs.llvm.org/show_bug.cgi?id=31852 | |
1635 | private: | |
1636 | #endif | |
1637 | ||
9189f559 | 1638 | template<size_t _Np, typename _Vp> |
4b7a3ab8 JW |
1639 | friend constexpr decltype(auto) |
1640 | __detail::__variant::__get(_Vp&& __v) noexcept; | |
9189f559 | 1641 | |
197c757c | 1642 | template<typename _Vp> |
4b7a3ab8 JW |
1643 | friend void* |
1644 | __detail::__variant::__get_storage(_Vp&& __v) noexcept; | |
9189f559 | 1645 | |
d255829b TS |
1646 | #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP) \ |
1647 | template<typename... _Tp> \ | |
1648 | friend constexpr bool \ | |
1649 | operator __OP(const variant<_Tp...>& __lhs, \ | |
1650 | const variant<_Tp...>& __rhs); | |
1651 | ||
1652 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<) | |
1653 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<=) | |
1654 | _VARIANT_RELATION_FUNCTION_TEMPLATE(==) | |
1655 | _VARIANT_RELATION_FUNCTION_TEMPLATE(!=) | |
1656 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>=) | |
1657 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>) | |
9189f559 | 1658 | |
d255829b | 1659 | #undef _VARIANT_RELATION_FUNCTION_TEMPLATE |
197c757c TS |
1660 | }; |
1661 | ||
197c757c | 1662 | template<size_t _Np, typename... _Types> |
9189f559 | 1663 | constexpr variant_alternative_t<_Np, variant<_Types...>>& |
197c757c TS |
1664 | get(variant<_Types...>& __v) |
1665 | { | |
1666 | static_assert(_Np < sizeof...(_Types), | |
801b2266 | 1667 | "The index must be in [0, number of alternatives)"); |
197c757c | 1668 | if (__v.index() != _Np) |
c43c3af2 | 1669 | __throw_bad_variant_access(__v.valueless_by_exception()); |
9189f559 | 1670 | return __detail::__variant::__get<_Np>(__v); |
197c757c TS |
1671 | } |
1672 | ||
1673 | template<size_t _Np, typename... _Types> | |
9189f559 | 1674 | constexpr variant_alternative_t<_Np, variant<_Types...>>&& |
197c757c TS |
1675 | get(variant<_Types...>&& __v) |
1676 | { | |
1677 | static_assert(_Np < sizeof...(_Types), | |
801b2266 | 1678 | "The index must be in [0, number of alternatives)"); |
197c757c | 1679 | if (__v.index() != _Np) |
c43c3af2 | 1680 | __throw_bad_variant_access(__v.valueless_by_exception()); |
9189f559 | 1681 | return __detail::__variant::__get<_Np>(std::move(__v)); |
197c757c TS |
1682 | } |
1683 | ||
1684 | template<size_t _Np, typename... _Types> | |
9189f559 | 1685 | constexpr const variant_alternative_t<_Np, variant<_Types...>>& |
197c757c TS |
1686 | get(const variant<_Types...>& __v) |
1687 | { | |
1688 | static_assert(_Np < sizeof...(_Types), | |
801b2266 | 1689 | "The index must be in [0, number of alternatives)"); |
197c757c | 1690 | if (__v.index() != _Np) |
c43c3af2 | 1691 | __throw_bad_variant_access(__v.valueless_by_exception()); |
9189f559 | 1692 | return __detail::__variant::__get<_Np>(__v); |
197c757c TS |
1693 | } |
1694 | ||
1695 | template<size_t _Np, typename... _Types> | |
9189f559 | 1696 | constexpr const variant_alternative_t<_Np, variant<_Types...>>&& |
197c757c TS |
1697 | get(const variant<_Types...>&& __v) |
1698 | { | |
1699 | static_assert(_Np < sizeof...(_Types), | |
801b2266 | 1700 | "The index must be in [0, number of alternatives)"); |
197c757c | 1701 | if (__v.index() != _Np) |
c43c3af2 | 1702 | __throw_bad_variant_access(__v.valueless_by_exception()); |
9189f559 | 1703 | return __detail::__variant::__get<_Np>(std::move(__v)); |
197c757c TS |
1704 | } |
1705 | ||
956a62aa | 1706 | template<typename _Result_type, typename _Visitor, typename... _Variants> |
b01af236 | 1707 | constexpr decltype(auto) |
669a6fdc | 1708 | __do_visit(_Visitor&& __visitor, _Variants&&... __variants) |
197c757c | 1709 | { |
b01af236 TS |
1710 | constexpr auto& __vtable = __detail::__variant::__gen_vtable< |
1711 | _Result_type, _Visitor&&, _Variants&&...>::_S_vtable; | |
1712 | ||
1713 | auto __func_ptr = __vtable._M_access(__variants.index()...); | |
64626fca | 1714 | return (*__func_ptr)(std::forward<_Visitor>(__visitor), |
b01af236 | 1715 | std::forward<_Variants>(__variants)...); |
197c757c TS |
1716 | } |
1717 | ||
3427e313 VV |
1718 | template<typename _Tp, typename... _Types> |
1719 | constexpr inline bool __same_types = (is_same_v<_Tp, _Types> && ...); | |
1720 | ||
02cbd79e | 1721 | template <size_t _Idx, typename _Visitor, typename _Variant> |
3427e313 VV |
1722 | decltype(auto) |
1723 | __check_visitor_result(_Visitor&& __vis, _Variant&& __variant) | |
1724 | { | |
1725 | return std::__invoke(std::forward<_Visitor>(__vis), | |
1726 | std::get<_Idx>(std::forward<_Variant>(__variant))); | |
1727 | } | |
1728 | ||
02cbd79e | 1729 | template <typename _Visitor, typename _Variant, size_t... _Idxs> |
3427e313 VV |
1730 | constexpr bool __check_visitor_results(std::index_sequence<_Idxs...>) |
1731 | { | |
1732 | return __same_types<decltype(__check_visitor_result<_Idxs>( | |
1733 | std::declval<_Visitor>(), | |
1734 | std::declval<_Variant>()))...>; | |
1735 | } | |
1736 | ||
1737 | ||
669a6fdc VV |
1738 | template<typename _Visitor, typename... _Variants> |
1739 | constexpr decltype(auto) | |
1740 | visit(_Visitor&& __visitor, _Variants&&... __variants) | |
1741 | { | |
1742 | if ((__variants.valueless_by_exception() || ...)) | |
c43c3af2 | 1743 | __throw_bad_variant_access("std::visit: variant is valueless"); |
669a6fdc | 1744 | |
956a62aa JW |
1745 | using _Result_type = std::invoke_result_t<_Visitor, |
1746 | decltype(std::get<0>(std::declval<_Variants>()))...>; | |
1747 | ||
1748 | using _Tag = __detail::__variant::__deduce_visit_result<_Result_type>; | |
1749 | ||
3427e313 VV |
1750 | if constexpr (sizeof...(_Variants) == 1) |
1751 | { | |
1752 | constexpr bool __visit_rettypes_match = | |
1753 | __check_visitor_results<_Visitor, _Variants...>( | |
1754 | std::make_index_sequence< | |
1755 | std::variant_size<remove_reference_t<_Variants>...>::value>()); | |
1756 | if constexpr (!__visit_rettypes_match) | |
1757 | { | |
1758 | static_assert(__visit_rettypes_match, | |
1759 | "std::visit requires the visitor to have the same " | |
1760 | "return type for all alternatives of a variant"); | |
1761 | return; | |
1762 | } | |
1763 | else | |
1764 | return std::__do_visit<_Tag>( | |
1765 | std::forward<_Visitor>(__visitor), | |
1766 | std::forward<_Variants>(__variants)...); | |
1767 | } | |
1768 | else | |
1769 | return std::__do_visit<_Tag>( | |
1770 | std::forward<_Visitor>(__visitor), | |
1771 | std::forward<_Variants>(__variants)...); | |
669a6fdc VV |
1772 | } |
1773 | ||
199b20e3 JW |
1774 | #if __cplusplus > 201703L |
1775 | template<typename _Res, typename _Visitor, typename... _Variants> | |
1776 | constexpr _Res | |
1777 | visit(_Visitor&& __visitor, _Variants&&... __variants) | |
1778 | { | |
1779 | if ((__variants.valueless_by_exception() || ...)) | |
c43c3af2 | 1780 | __throw_bad_variant_access("std::visit<R>: variant is valueless"); |
199b20e3 | 1781 | |
e5d7010b JW |
1782 | return std::__do_visit<_Res>(std::forward<_Visitor>(__visitor), |
1783 | std::forward<_Variants>(__variants)...); | |
199b20e3 JW |
1784 | } |
1785 | #endif | |
1786 | ||
509912a6 VV |
1787 | template<bool, typename... _Types> |
1788 | struct __variant_hash_call_base_impl | |
197c757c | 1789 | { |
197c757c TS |
1790 | size_t |
1791 | operator()(const variant<_Types...>& __t) const | |
7dcc645c | 1792 | noexcept((is_nothrow_invocable_v<hash<decay_t<_Types>>, _Types> && ...)) |
197c757c | 1793 | { |
669a6fdc | 1794 | size_t __ret; |
956a62aa JW |
1795 | __detail::__variant::__raw_visit( |
1796 | [&__t, &__ret](auto&& __t_mem) mutable | |
197c757c | 1797 | { |
669a6fdc VV |
1798 | using _Type = __remove_cvref_t<decltype(__t_mem)>; |
1799 | if constexpr (!is_same_v<_Type, | |
1800 | __detail::__variant::__variant_cookie>) | |
1801 | __ret = std::hash<size_t>{}(__t.index()) | |
1802 | + std::hash<_Type>{}(__t_mem); | |
1803 | else | |
1804 | __ret = std::hash<size_t>{}(__t.index()); | |
669a6fdc VV |
1805 | }, __t); |
1806 | return __ret; | |
197c757c TS |
1807 | } |
1808 | }; | |
1809 | ||
509912a6 VV |
1810 | template<typename... _Types> |
1811 | struct __variant_hash_call_base_impl<false, _Types...> {}; | |
1812 | ||
1813 | template<typename... _Types> | |
1814 | using __variant_hash_call_base = | |
1815 | __variant_hash_call_base_impl<(__poison_hash<remove_const_t<_Types>>:: | |
1816 | __enable_hash_call &&...), _Types...>; | |
1817 | ||
1818 | template<typename... _Types> | |
1819 | struct hash<variant<_Types...>> | |
1820 | : private __detail::__variant::_Variant_hash_base< | |
4a15d842 | 1821 | variant<_Types...>, std::index_sequence_for<_Types...>>, |
509912a6 VV |
1822 | public __variant_hash_call_base<_Types...> |
1823 | { | |
f78958c9 JW |
1824 | using result_type [[__deprecated__]] = size_t; |
1825 | using argument_type [[__deprecated__]] = variant<_Types...>; | |
509912a6 VV |
1826 | }; |
1827 | ||
197c757c TS |
1828 | template<> |
1829 | struct hash<monostate> | |
1830 | { | |
f78958c9 JW |
1831 | using result_type [[__deprecated__]] = size_t; |
1832 | using argument_type [[__deprecated__]] = monostate; | |
197c757c TS |
1833 | |
1834 | size_t | |
801b2266 | 1835 | operator()(const monostate&) const noexcept |
197c757c TS |
1836 | { |
1837 | constexpr size_t __magic_monostate_hash = -7777; | |
1838 | return __magic_monostate_hash; | |
1839 | } | |
1840 | }; | |
1841 | ||
f78958c9 JW |
1842 | template<typename... _Types> |
1843 | struct __is_fast_hash<hash<variant<_Types...>>> | |
1844 | : bool_constant<(__is_fast_hash<_Types>::value && ...)> | |
1845 | { }; | |
1846 | ||
197c757c TS |
1847 | _GLIBCXX_END_NAMESPACE_VERSION |
1848 | } // namespace std | |
1849 | ||
1850 | #endif // C++17 | |
1851 | ||
1852 | #endif // _GLIBCXX_VARIANT |