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85adbce1 | 1 | // <variant> -*- C++ -*- |
2 | ||
fbd26352 | 3 | // Copyright (C) 2016-2019 Free Software Foundation, Inc. |
85adbce1 | 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 | |
26 | * This is the <variant> C++ Library header. | |
27 | */ | |
28 | ||
29 | #ifndef _GLIBCXX_VARIANT | |
30 | #define _GLIBCXX_VARIANT 1 | |
31 | ||
32 | #pragma GCC system_header | |
33 | ||
a9e86108 | 34 | #if __cplusplus >= 201703L |
85adbce1 | 35 | |
36 | #include <type_traits> | |
37 | #include <utility> | |
38 | #include <bits/enable_special_members.h> | |
d923797a | 39 | #include <bits/functexcept.h> |
4b3b2026 | 40 | #include <bits/move.h> |
17515fad | 41 | #include <bits/functional_hash.h> |
2a5d61f9 | 42 | #include <bits/invoke.h> |
caaaa8fd | 43 | #include <ext/aligned_buffer.h> |
cfdb4aba | 44 | #include <bits/parse_numbers.h> |
ae8365d5 | 45 | #include <bits/stl_iterator_base_types.h> |
46 | #include <bits/stl_iterator_base_funcs.h> | |
47 | #include <bits/stl_construct.h> | |
85adbce1 | 48 | |
49 | namespace std _GLIBCXX_VISIBILITY(default) | |
50 | { | |
ae6a4ce9 | 51 | _GLIBCXX_BEGIN_NAMESPACE_VERSION |
52 | ||
2a5d61f9 | 53 | namespace __detail |
54 | { | |
55 | namespace __variant | |
56 | { | |
2a5d61f9 | 57 | template<size_t _Np, typename... _Types> |
58 | struct _Nth_type; | |
59 | ||
60 | template<size_t _Np, typename _First, typename... _Rest> | |
61 | struct _Nth_type<_Np, _First, _Rest...> | |
62 | : _Nth_type<_Np-1, _Rest...> { }; | |
63 | ||
64 | template<typename _First, typename... _Rest> | |
65 | struct _Nth_type<0, _First, _Rest...> | |
66 | { using type = _First; }; | |
67 | ||
2a5d61f9 | 68 | } // namespace __variant |
69 | } // namespace __detail | |
70 | ||
d253bcb1 | 71 | #define __cpp_lib_variant 201606L |
a9e86108 | 72 | |
85adbce1 | 73 | template<typename... _Types> class tuple; |
74 | template<typename... _Types> class variant; | |
75 | template <typename> struct hash; | |
76 | ||
77 | template<typename _Variant> | |
78 | struct variant_size; | |
79 | ||
80 | template<typename _Variant> | |
81 | struct variant_size<const _Variant> : variant_size<_Variant> {}; | |
82 | ||
83 | template<typename _Variant> | |
84 | struct variant_size<volatile _Variant> : variant_size<_Variant> {}; | |
85 | ||
86 | template<typename _Variant> | |
87 | struct variant_size<const volatile _Variant> : variant_size<_Variant> {}; | |
88 | ||
89 | template<typename... _Types> | |
90 | struct variant_size<variant<_Types...>> | |
91 | : std::integral_constant<size_t, sizeof...(_Types)> {}; | |
92 | ||
93 | template<typename _Variant> | |
b5492afc | 94 | inline constexpr size_t variant_size_v = variant_size<_Variant>::value; |
85adbce1 | 95 | |
96 | template<size_t _Np, typename _Variant> | |
97 | struct variant_alternative; | |
98 | ||
99 | template<size_t _Np, typename _First, typename... _Rest> | |
100 | struct variant_alternative<_Np, variant<_First, _Rest...>> | |
101 | : variant_alternative<_Np-1, variant<_Rest...>> {}; | |
102 | ||
103 | template<typename _First, typename... _Rest> | |
104 | struct variant_alternative<0, variant<_First, _Rest...>> | |
105 | { using type = _First; }; | |
106 | ||
107 | template<size_t _Np, typename _Variant> | |
108 | using variant_alternative_t = | |
109 | typename variant_alternative<_Np, _Variant>::type; | |
110 | ||
909ccf61 | 111 | template<size_t _Np, typename _Variant> |
112 | struct variant_alternative<_Np, const _Variant> | |
113 | { using type = add_const_t<variant_alternative_t<_Np, _Variant>>; }; | |
114 | ||
115 | template<size_t _Np, typename _Variant> | |
116 | struct variant_alternative<_Np, volatile _Variant> | |
117 | { using type = add_volatile_t<variant_alternative_t<_Np, _Variant>>; }; | |
118 | ||
119 | template<size_t _Np, typename _Variant> | |
120 | struct variant_alternative<_Np, const volatile _Variant> | |
121 | { using type = add_cv_t<variant_alternative_t<_Np, _Variant>>; }; | |
122 | ||
b5492afc | 123 | inline constexpr size_t variant_npos = -1; |
85adbce1 | 124 | |
2a5d61f9 | 125 | template<size_t _Np, typename... _Types> |
126 | constexpr variant_alternative_t<_Np, variant<_Types...>>& | |
127 | get(variant<_Types...>&); | |
128 | ||
129 | template<size_t _Np, typename... _Types> | |
130 | constexpr variant_alternative_t<_Np, variant<_Types...>>&& | |
131 | get(variant<_Types...>&&); | |
132 | ||
133 | template<size_t _Np, typename... _Types> | |
134 | constexpr variant_alternative_t<_Np, variant<_Types...>> const& | |
135 | get(const variant<_Types...>&); | |
136 | ||
137 | template<size_t _Np, typename... _Types> | |
138 | constexpr variant_alternative_t<_Np, variant<_Types...>> const&& | |
139 | get(const variant<_Types...>&&); | |
140 | ||
f03f26fa | 141 | template<typename _Result_type, typename _Visitor, typename... _Variants> |
49c83dca | 142 | constexpr decltype(auto) |
143 | __do_visit(_Visitor&& __visitor, _Variants&&... __variants); | |
144 | ||
145 | template <typename... _Types, typename _Tp> | |
492debfa | 146 | decltype(auto) |
147 | __variant_cast(_Tp&& __rhs) | |
49c83dca | 148 | { |
149 | if constexpr (is_lvalue_reference_v<_Tp>) | |
150 | { | |
151 | if constexpr (is_const_v<remove_reference_t<_Tp>>) | |
152 | return static_cast<const variant<_Types...>&>(__rhs); | |
153 | else | |
154 | return static_cast<variant<_Types...>&>(__rhs); | |
155 | } | |
156 | else | |
157 | return static_cast<variant<_Types...>&&>(__rhs); | |
158 | } | |
159 | ||
85adbce1 | 160 | namespace __detail |
161 | { | |
162 | namespace __variant | |
163 | { | |
164 | // Returns the first apparence of _Tp in _Types. | |
165 | // Returns sizeof...(_Types) if _Tp is not in _Types. | |
166 | template<typename _Tp, typename... _Types> | |
167 | struct __index_of : std::integral_constant<size_t, 0> {}; | |
168 | ||
169 | template<typename _Tp, typename... _Types> | |
b5492afc | 170 | inline constexpr size_t __index_of_v = __index_of<_Tp, _Types...>::value; |
85adbce1 | 171 | |
172 | template<typename _Tp, typename _First, typename... _Rest> | |
173 | struct __index_of<_Tp, _First, _Rest...> : | |
174 | std::integral_constant<size_t, is_same_v<_Tp, _First> | |
175 | ? 0 : __index_of_v<_Tp, _Rest...> + 1> {}; | |
176 | ||
49c83dca | 177 | // used for raw visitation |
178 | struct __variant_cookie {}; | |
4f3e024d | 179 | // used for raw visitation with indices passed in |
47cf9c4c | 180 | struct __variant_idx_cookie { using type = __variant_idx_cookie; }; |
f03f26fa | 181 | // Used to enable deduction (and same-type checking) for std::visit: |
182 | template<typename> struct __deduce_visit_result { }; | |
183 | ||
184 | // Visit variants that might be valueless. | |
185 | template<typename _Visitor, typename... _Variants> | |
186 | constexpr void | |
187 | __raw_visit(_Visitor&& __visitor, _Variants&&... __variants) | |
188 | { | |
189 | std::__do_visit<__variant_cookie>(std::forward<_Visitor>(__visitor), | |
190 | std::forward<_Variants>(__variants)...); | |
191 | } | |
192 | ||
193 | // Visit variants that might be valueless, passing indices to the visitor. | |
194 | template<typename _Visitor, typename... _Variants> | |
195 | constexpr void | |
196 | __raw_idx_visit(_Visitor&& __visitor, _Variants&&... __variants) | |
197 | { | |
198 | std::__do_visit<__variant_idx_cookie>(std::forward<_Visitor>(__visitor), | |
199 | std::forward<_Variants>(__variants)...); | |
200 | } | |
49c83dca | 201 | |
caaaa8fd | 202 | // _Uninitialized<T> is guaranteed to be a literal type, even if T is not. |
203 | // We have to do this, because [basic.types]p10.5.3 (n4606) is not implemented | |
204 | // yet. When it's implemented, _Uninitialized<T> can be changed to the alias | |
205 | // to T, therefore equivalent to being removed entirely. | |
206 | // | |
207 | // Another reason we may not want to remove _Uninitialzied<T> may be that, we | |
208 | // want _Uninitialized<T> to be trivially destructible, no matter whether T | |
209 | // is; but we will see. | |
210 | template<typename _Type, bool = std::is_literal_type_v<_Type>> | |
85adbce1 | 211 | struct _Uninitialized; |
212 | ||
213 | template<typename _Type> | |
214 | struct _Uninitialized<_Type, true> | |
215 | { | |
85adbce1 | 216 | template<typename... _Args> |
492debfa | 217 | constexpr |
218 | _Uninitialized(in_place_index_t<0>, _Args&&... __args) | |
219 | : _M_storage(std::forward<_Args>(__args)...) | |
220 | { } | |
85adbce1 | 221 | |
e11f5aed | 222 | constexpr const _Type& _M_get() const & noexcept |
caaaa8fd | 223 | { return _M_storage; } |
224 | ||
e11f5aed | 225 | constexpr _Type& _M_get() & noexcept |
caaaa8fd | 226 | { return _M_storage; } |
227 | ||
e11f5aed | 228 | constexpr const _Type&& _M_get() const && noexcept |
caaaa8fd | 229 | { return std::move(_M_storage); } |
230 | ||
e11f5aed | 231 | constexpr _Type&& _M_get() && noexcept |
caaaa8fd | 232 | { return std::move(_M_storage); } |
233 | ||
85adbce1 | 234 | _Type _M_storage; |
235 | }; | |
236 | ||
237 | template<typename _Type> | |
238 | struct _Uninitialized<_Type, false> | |
239 | { | |
85adbce1 | 240 | template<typename... _Args> |
492debfa | 241 | constexpr |
242 | _Uninitialized(in_place_index_t<0>, _Args&&... __args) | |
243 | { | |
244 | ::new ((void*)std::addressof(_M_storage)) | |
245 | _Type(std::forward<_Args>(__args)...); | |
246 | } | |
85adbce1 | 247 | |
e11f5aed | 248 | const _Type& _M_get() const & noexcept |
caaaa8fd | 249 | { return *_M_storage._M_ptr(); } |
250 | ||
e11f5aed | 251 | _Type& _M_get() & noexcept |
caaaa8fd | 252 | { return *_M_storage._M_ptr(); } |
253 | ||
e11f5aed | 254 | const _Type&& _M_get() const && noexcept |
caaaa8fd | 255 | { return std::move(*_M_storage._M_ptr()); } |
256 | ||
e11f5aed | 257 | _Type&& _M_get() && noexcept |
caaaa8fd | 258 | { return std::move(*_M_storage._M_ptr()); } |
259 | ||
260 | __gnu_cxx::__aligned_membuf<_Type> _M_storage; | |
85adbce1 | 261 | }; |
262 | ||
caaaa8fd | 263 | template<typename _Union> |
e11f5aed | 264 | constexpr decltype(auto) |
265 | __get(in_place_index_t<0>, _Union&& __u) noexcept | |
caaaa8fd | 266 | { return std::forward<_Union>(__u)._M_first._M_get(); } |
267 | ||
268 | template<size_t _Np, typename _Union> | |
e11f5aed | 269 | constexpr decltype(auto) |
270 | __get(in_place_index_t<_Np>, _Union&& __u) noexcept | |
a8f8d460 | 271 | { |
272 | return __variant::__get(in_place_index<_Np-1>, | |
273 | std::forward<_Union>(__u)._M_rest); | |
274 | } | |
caaaa8fd | 275 | |
276 | // Returns the typed storage for __v. | |
277 | template<size_t _Np, typename _Variant> | |
e11f5aed | 278 | constexpr decltype(auto) |
279 | __get(_Variant&& __v) noexcept | |
caaaa8fd | 280 | { |
a8f8d460 | 281 | return __variant::__get(std::in_place_index<_Np>, |
282 | std::forward<_Variant>(__v)._M_u); | |
caaaa8fd | 283 | } |
284 | ||
77c62063 | 285 | template<typename... _Types> |
286 | struct _Traits | |
287 | { | |
288 | static constexpr bool _S_default_ctor = | |
ae6a4ce9 | 289 | is_default_constructible_v<typename _Nth_type<0, _Types...>::type>; |
77c62063 | 290 | static constexpr bool _S_copy_ctor = |
ae6a4ce9 | 291 | (is_copy_constructible_v<_Types> && ...); |
77c62063 | 292 | static constexpr bool _S_move_ctor = |
ae6a4ce9 | 293 | (is_move_constructible_v<_Types> && ...); |
77c62063 | 294 | static constexpr bool _S_copy_assign = |
37a7dbf9 | 295 | _S_copy_ctor |
ae6a4ce9 | 296 | && (is_copy_assignable_v<_Types> && ...); |
77c62063 | 297 | static constexpr bool _S_move_assign = |
ae6a4ce9 | 298 | _S_move_ctor |
299 | && (is_move_assignable_v<_Types> && ...); | |
77c62063 | 300 | |
301 | static constexpr bool _S_trivial_dtor = | |
ae6a4ce9 | 302 | (is_trivially_destructible_v<_Types> && ...); |
77c62063 | 303 | static constexpr bool _S_trivial_copy_ctor = |
ae6a4ce9 | 304 | (is_trivially_copy_constructible_v<_Types> && ...); |
77c62063 | 305 | static constexpr bool _S_trivial_move_ctor = |
ae6a4ce9 | 306 | (is_trivially_move_constructible_v<_Types> && ...); |
77c62063 | 307 | static constexpr bool _S_trivial_copy_assign = |
a4265b66 | 308 | _S_trivial_dtor && _S_trivial_copy_ctor |
309 | && (is_trivially_copy_assignable_v<_Types> && ...); | |
77c62063 | 310 | static constexpr bool _S_trivial_move_assign = |
a4265b66 | 311 | _S_trivial_dtor && _S_trivial_move_ctor |
312 | && (is_trivially_move_assignable_v<_Types> && ...); | |
77c62063 | 313 | |
314 | // The following nothrow traits are for non-trivial SMFs. Trivial SMFs | |
315 | // are always nothrow. | |
316 | static constexpr bool _S_nothrow_default_ctor = | |
ae6a4ce9 | 317 | is_nothrow_default_constructible_v< |
318 | typename _Nth_type<0, _Types...>::type>; | |
77c62063 | 319 | static constexpr bool _S_nothrow_copy_ctor = false; |
320 | static constexpr bool _S_nothrow_move_ctor = | |
ae6a4ce9 | 321 | (is_nothrow_move_constructible_v<_Types> && ...); |
77c62063 | 322 | static constexpr bool _S_nothrow_copy_assign = false; |
323 | static constexpr bool _S_nothrow_move_assign = | |
a4265b66 | 324 | _S_nothrow_move_ctor |
325 | && (is_nothrow_move_assignable_v<_Types> && ...); | |
77c62063 | 326 | }; |
327 | ||
caaaa8fd | 328 | // Defines members and ctors. |
85adbce1 | 329 | template<typename... _Types> |
caaaa8fd | 330 | union _Variadic_union { }; |
85adbce1 | 331 | |
85adbce1 | 332 | template<typename _First, typename... _Rest> |
caaaa8fd | 333 | union _Variadic_union<_First, _Rest...> |
85adbce1 | 334 | { |
caaaa8fd | 335 | constexpr _Variadic_union() : _M_rest() { } |
336 | ||
337 | template<typename... _Args> | |
338 | constexpr _Variadic_union(in_place_index_t<0>, _Args&&... __args) | |
339 | : _M_first(in_place_index<0>, std::forward<_Args>(__args)...) | |
340 | { } | |
341 | ||
342 | template<size_t _Np, typename... _Args> | |
343 | constexpr _Variadic_union(in_place_index_t<_Np>, _Args&&... __args) | |
344 | : _M_rest(in_place_index<_Np-1>, std::forward<_Args>(__args)...) | |
345 | { } | |
346 | ||
347 | _Uninitialized<_First> _M_first; | |
348 | _Variadic_union<_Rest...> _M_rest; | |
349 | }; | |
350 | ||
781cb64d | 351 | // _Never_valueless_alt is true for variant alternatives that can |
352 | // always be placed in a variant without it becoming valueless. | |
353 | ||
354 | // For suitably-small, trivially copyable types we can create temporaries | |
355 | // on the stack and then memcpy them into place. | |
356 | template<typename _Tp> | |
357 | struct _Never_valueless_alt | |
358 | : __and_<bool_constant<sizeof(_Tp) <= 256>, is_trivially_copyable<_Tp>> | |
359 | { }; | |
360 | ||
361 | // Specialize _Never_valueless_alt for other types which have a | |
b9d8292f | 362 | // non-throwing and cheap move construction and move assignment operator, |
363 | // so that emplacing the type will provide the strong exception-safety | |
364 | // guarantee, by creating and moving a temporary. | |
781cb64d | 365 | // Whether _Never_valueless_alt<T> is true or not affects the ABI of a |
366 | // variant using that alternative, so we can't change the value later! | |
367 | ||
368 | // True if every alternative in _Types... can be emplaced in a variant | |
369 | // without it becoming valueless. If this is true, variant<_Types...> | |
370 | // can never be valueless, which enables some minor optimizations. | |
4c0ef551 | 371 | template <typename... _Types> |
781cb64d | 372 | constexpr bool __never_valueless() |
373 | { | |
b9d8292f | 374 | return _Traits<_Types...>::_S_move_assign |
375 | && (_Never_valueless_alt<_Types>::value && ...); | |
781cb64d | 376 | } |
4c0ef551 | 377 | |
caaaa8fd | 378 | // Defines index and the dtor, possibly trivial. |
379 | template<bool __trivially_destructible, typename... _Types> | |
380 | struct _Variant_storage; | |
381 | ||
cfdb4aba | 382 | template <typename... _Types> |
492debfa | 383 | using __select_index = |
384 | typename __select_int::_Select_int_base<sizeof...(_Types), | |
385 | unsigned char, | |
386 | unsigned short>::type::value_type; | |
cfdb4aba | 387 | |
caaaa8fd | 388 | template<typename... _Types> |
389 | struct _Variant_storage<false, _Types...> | |
390 | { | |
caaaa8fd | 391 | constexpr _Variant_storage() : _M_index(variant_npos) { } |
85adbce1 | 392 | |
56835b0d | 393 | template<size_t _Np, typename... _Args> |
85adbce1 | 394 | constexpr _Variant_storage(in_place_index_t<_Np>, _Args&&... __args) |
caaaa8fd | 395 | : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...), |
396 | _M_index(_Np) | |
85adbce1 | 397 | { } |
398 | ||
49c83dca | 399 | constexpr void _M_reset_impl() |
400 | { | |
f03f26fa | 401 | __variant::__raw_visit([](auto&& __this_mem) mutable |
49c83dca | 402 | { |
403 | if constexpr (!is_same_v<remove_reference_t<decltype(__this_mem)>, | |
404 | __variant_cookie>) | |
405 | std::_Destroy(std::__addressof(__this_mem)); | |
49c83dca | 406 | }, __variant_cast<_Types...>(*this)); |
492debfa | 407 | } |
85adbce1 | 408 | |
a6787bda | 409 | void _M_reset() |
410 | { | |
49c83dca | 411 | _M_reset_impl(); |
a6787bda | 412 | _M_index = variant_npos; |
413 | } | |
414 | ||
caaaa8fd | 415 | ~_Variant_storage() |
a6787bda | 416 | { _M_reset(); } |
85adbce1 | 417 | |
77c62063 | 418 | void* |
5c6334a5 | 419 | _M_storage() const noexcept |
77c62063 | 420 | { |
421 | return const_cast<void*>(static_cast<const void*>( | |
422 | std::addressof(_M_u))); | |
423 | } | |
424 | ||
425 | constexpr bool | |
426 | _M_valid() const noexcept | |
427 | { | |
b9d8292f | 428 | if constexpr (__never_valueless<_Types...>()) |
429 | return true; | |
77c62063 | 430 | return this->_M_index != __index_type(variant_npos); |
431 | } | |
432 | ||
caaaa8fd | 433 | _Variadic_union<_Types...> _M_u; |
cfdb4aba | 434 | using __index_type = __select_index<_Types...>; |
435 | __index_type _M_index; | |
85adbce1 | 436 | }; |
437 | ||
caaaa8fd | 438 | template<typename... _Types> |
439 | struct _Variant_storage<true, _Types...> | |
85adbce1 | 440 | { |
caaaa8fd | 441 | constexpr _Variant_storage() : _M_index(variant_npos) { } |
85adbce1 | 442 | |
caaaa8fd | 443 | template<size_t _Np, typename... _Args> |
444 | constexpr _Variant_storage(in_place_index_t<_Np>, _Args&&... __args) | |
445 | : _M_u(in_place_index<_Np>, std::forward<_Args>(__args)...), | |
446 | _M_index(_Np) | |
447 | { } | |
448 | ||
5c6334a5 | 449 | void _M_reset() noexcept |
a6787bda | 450 | { _M_index = variant_npos; } |
451 | ||
77c62063 | 452 | void* |
5c6334a5 | 453 | _M_storage() const noexcept |
77c62063 | 454 | { |
455 | return const_cast<void*>(static_cast<const void*>( | |
456 | std::addressof(_M_u))); | |
457 | } | |
458 | ||
459 | constexpr bool | |
460 | _M_valid() const noexcept | |
461 | { | |
4c0ef551 | 462 | if constexpr (__never_valueless<_Types...>()) |
bc35ec6d | 463 | return true; |
77c62063 | 464 | return this->_M_index != __index_type(variant_npos); |
465 | } | |
466 | ||
caaaa8fd | 467 | _Variadic_union<_Types...> _M_u; |
cfdb4aba | 468 | using __index_type = __select_index<_Types...>; |
469 | __index_type _M_index; | |
85adbce1 | 470 | }; |
471 | ||
85adbce1 | 472 | template<typename... _Types> |
77c62063 | 473 | using _Variant_storage_alias = |
ae6a4ce9 | 474 | _Variant_storage<_Traits<_Types...>::_S_trivial_dtor, _Types...>; |
85adbce1 | 475 | |
225ca87b | 476 | template<typename _Tp, typename _Up> |
477 | void __variant_construct_single(_Tp&& __lhs, _Up&& __rhs_mem) | |
478 | { | |
479 | void* __storage = std::addressof(__lhs._M_u); | |
480 | using _Type = remove_reference_t<decltype(__rhs_mem)>; | |
481 | if constexpr (!is_same_v<_Type, __variant_cookie>) | |
482 | ::new (__storage) | |
483 | _Type(std::forward<decltype(__rhs_mem)>(__rhs_mem)); | |
484 | } | |
485 | ||
49c83dca | 486 | template<typename... _Types, typename _Tp, typename _Up> |
487 | void __variant_construct(_Tp&& __lhs, _Up&& __rhs) | |
488 | { | |
489 | __lhs._M_index = __rhs._M_index; | |
f03f26fa | 490 | __variant::__raw_visit([&__lhs](auto&& __rhs_mem) mutable |
49c83dca | 491 | { |
225ca87b | 492 | __variant_construct_single(std::forward<_Tp>(__lhs), |
fd1863e1 | 493 | std::forward<decltype(__rhs_mem)>(__rhs_mem)); |
fd1863e1 | 494 | }, __variant_cast<_Types...>(std::forward<_Up>(__rhs))); |
49c83dca | 495 | } |
496 | ||
77c62063 | 497 | // The following are (Copy|Move) (ctor|assign) layers for forwarding |
498 | // triviality and handling non-trivial SMF behaviors. | |
499 | ||
500 | template<bool, typename... _Types> | |
501 | struct _Copy_ctor_base : _Variant_storage_alias<_Types...> | |
502 | { | |
503 | using _Base = _Variant_storage_alias<_Types...>; | |
504 | using _Base::_Base; | |
85adbce1 | 505 | |
77c62063 | 506 | _Copy_ctor_base(const _Copy_ctor_base& __rhs) |
ae6a4ce9 | 507 | noexcept(_Traits<_Types...>::_S_nothrow_copy_ctor) |
85adbce1 | 508 | { |
49c83dca | 509 | __variant_construct<_Types...>(*this, __rhs); |
85adbce1 | 510 | } |
511 | ||
77c62063 | 512 | _Copy_ctor_base(_Copy_ctor_base&&) = default; |
513 | _Copy_ctor_base& operator=(const _Copy_ctor_base&) = default; | |
514 | _Copy_ctor_base& operator=(_Copy_ctor_base&&) = default; | |
515 | }; | |
516 | ||
517 | template<typename... _Types> | |
518 | struct _Copy_ctor_base<true, _Types...> : _Variant_storage_alias<_Types...> | |
519 | { | |
520 | using _Base = _Variant_storage_alias<_Types...>; | |
521 | using _Base::_Base; | |
522 | }; | |
523 | ||
524 | template<typename... _Types> | |
525 | using _Copy_ctor_alias = | |
ae6a4ce9 | 526 | _Copy_ctor_base<_Traits<_Types...>::_S_trivial_copy_ctor, _Types...>; |
77c62063 | 527 | |
528 | template<bool, typename... _Types> | |
529 | struct _Move_ctor_base : _Copy_ctor_alias<_Types...> | |
530 | { | |
531 | using _Base = _Copy_ctor_alias<_Types...>; | |
532 | using _Base::_Base; | |
533 | ||
534 | _Move_ctor_base(_Move_ctor_base&& __rhs) | |
ae6a4ce9 | 535 | noexcept(_Traits<_Types...>::_S_nothrow_move_ctor) |
85adbce1 | 536 | { |
fd1863e1 | 537 | __variant_construct<_Types...>(*this, std::move(__rhs)); |
49c83dca | 538 | } |
539 | ||
225ca87b | 540 | template<typename _Up> |
541 | void _M_destructive_move(unsigned short __rhs_index, _Up&& __rhs) | |
542 | { | |
543 | this->_M_reset(); | |
fd1863e1 | 544 | __variant_construct_single(*this, std::forward<_Up>(__rhs)); |
225ca87b | 545 | this->_M_index = __rhs_index; |
225ca87b | 546 | } |
85adbce1 | 547 | |
225ca87b | 548 | template<typename _Up> |
549 | void _M_destructive_copy(unsigned short __rhs_index, const _Up& __rhs) | |
550 | { | |
551 | this->_M_reset(); | |
fd1863e1 | 552 | __variant_construct_single(*this, __rhs); |
225ca87b | 553 | this->_M_index = __rhs_index; |
225ca87b | 554 | } |
a4c655fb | 555 | |
77c62063 | 556 | _Move_ctor_base(const _Move_ctor_base&) = default; |
557 | _Move_ctor_base& operator=(const _Move_ctor_base&) = default; | |
558 | _Move_ctor_base& operator=(_Move_ctor_base&&) = default; | |
559 | }; | |
560 | ||
561 | template<typename... _Types> | |
562 | struct _Move_ctor_base<true, _Types...> : _Copy_ctor_alias<_Types...> | |
563 | { | |
564 | using _Base = _Copy_ctor_alias<_Types...>; | |
565 | using _Base::_Base; | |
a4c655fb | 566 | |
225ca87b | 567 | template<typename _Up> |
568 | void _M_destructive_move(unsigned short __rhs_index, _Up&& __rhs) | |
569 | { | |
570 | this->_M_reset(); | |
fd1863e1 | 571 | __variant_construct_single(*this, std::forward<_Up>(__rhs)); |
225ca87b | 572 | this->_M_index = __rhs_index; |
225ca87b | 573 | } |
492debfa | 574 | |
225ca87b | 575 | template<typename _Up> |
576 | void _M_destructive_copy(unsigned short __rhs_index, const _Up& __rhs) | |
577 | { | |
578 | this->_M_reset(); | |
225ca87b | 579 | __variant_construct_single(*this, __rhs); |
fd1863e1 | 580 | this->_M_index = __rhs_index; |
225ca87b | 581 | } |
77c62063 | 582 | }; |
583 | ||
584 | template<typename... _Types> | |
585 | using _Move_ctor_alias = | |
ae6a4ce9 | 586 | _Move_ctor_base<_Traits<_Types...>::_S_trivial_move_ctor, _Types...>; |
77c62063 | 587 | |
588 | template<bool, typename... _Types> | |
589 | struct _Copy_assign_base : _Move_ctor_alias<_Types...> | |
590 | { | |
591 | using _Base = _Move_ctor_alias<_Types...>; | |
592 | using _Base::_Base; | |
85adbce1 | 593 | |
77c62063 | 594 | _Copy_assign_base& |
595 | operator=(const _Copy_assign_base& __rhs) | |
ae6a4ce9 | 596 | noexcept(_Traits<_Types...>::_S_nothrow_copy_assign) |
85adbce1 | 597 | { |
f03f26fa | 598 | __variant::__raw_idx_visit( |
599 | [this](auto&& __rhs_mem, auto __rhs_index) mutable | |
85adbce1 | 600 | { |
4f3e024d | 601 | if constexpr (__rhs_index != variant_npos) |
85adbce1 | 602 | { |
4f3e024d | 603 | if (this->_M_index == __rhs_index) |
fd1863e1 | 604 | __variant::__get<__rhs_index>(*this) = __rhs_mem; |
4f3e024d | 605 | else |
606 | { | |
fd1863e1 | 607 | using __rhs_type = __remove_cvref_t<decltype(__rhs_mem)>; |
608 | if constexpr (is_nothrow_copy_constructible_v<__rhs_type> | |
609 | || !is_nothrow_move_constructible_v<__rhs_type>) | |
610 | // The standard says this->emplace<__rhs_type>(__rhs_mem) | |
611 | // should be used here, but _M_destructive_copy is | |
612 | // equivalent in this case. Either copy construction | |
613 | // doesn't throw, so _M_destructive_copy gives strong | |
614 | // exception safety guarantee, or both copy construction | |
615 | // and move construction can throw, so emplace only gives | |
616 | // basic exception safety anyway. | |
617 | this->_M_destructive_copy(__rhs_index, __rhs_mem); | |
49c83dca | 618 | else |
fd1863e1 | 619 | __variant_cast<_Types...>(*this) |
620 | = variant<_Types...>(__rhs_mem); | |
49c83dca | 621 | } |
49c83dca | 622 | } |
4f3e024d | 623 | else |
624 | this->_M_reset(); | |
4f3e024d | 625 | }, __variant_cast<_Types...>(__rhs)); |
85adbce1 | 626 | return *this; |
627 | } | |
628 | ||
77c62063 | 629 | _Copy_assign_base(const _Copy_assign_base&) = default; |
630 | _Copy_assign_base(_Copy_assign_base&&) = default; | |
631 | _Copy_assign_base& operator=(_Copy_assign_base&&) = default; | |
632 | }; | |
633 | ||
634 | template<typename... _Types> | |
635 | struct _Copy_assign_base<true, _Types...> : _Move_ctor_alias<_Types...> | |
636 | { | |
637 | using _Base = _Move_ctor_alias<_Types...>; | |
638 | using _Base::_Base; | |
639 | }; | |
640 | ||
641 | template<typename... _Types> | |
642 | using _Copy_assign_alias = | |
a4265b66 | 643 | _Copy_assign_base<_Traits<_Types...>::_S_trivial_copy_assign, _Types...>; |
77c62063 | 644 | |
645 | template<bool, typename... _Types> | |
646 | struct _Move_assign_base : _Copy_assign_alias<_Types...> | |
647 | { | |
648 | using _Base = _Copy_assign_alias<_Types...>; | |
649 | using _Base::_Base; | |
650 | ||
77c62063 | 651 | _Move_assign_base& |
652 | operator=(_Move_assign_base&& __rhs) | |
ae6a4ce9 | 653 | noexcept(_Traits<_Types...>::_S_nothrow_move_assign) |
85adbce1 | 654 | { |
f03f26fa | 655 | __variant::__raw_idx_visit( |
656 | [this](auto&& __rhs_mem, auto __rhs_index) mutable | |
85adbce1 | 657 | { |
4f3e024d | 658 | if constexpr (__rhs_index != variant_npos) |
85adbce1 | 659 | { |
4f3e024d | 660 | if (this->_M_index == __rhs_index) |
fd1863e1 | 661 | __variant::__get<__rhs_index>(*this) = std::move(__rhs_mem); |
4f3e024d | 662 | else |
fd1863e1 | 663 | __variant_cast<_Types...>(*this) |
664 | .template emplace<__rhs_index>(std::move(__rhs_mem)); | |
85adbce1 | 665 | } |
49c83dca | 666 | else |
4f3e024d | 667 | this->_M_reset(); |
4f3e024d | 668 | }, __variant_cast<_Types...>(__rhs)); |
85adbce1 | 669 | return *this; |
670 | } | |
671 | ||
77c62063 | 672 | _Move_assign_base(const _Move_assign_base&) = default; |
673 | _Move_assign_base(_Move_assign_base&&) = default; | |
674 | _Move_assign_base& operator=(const _Move_assign_base&) = default; | |
675 | }; | |
85adbce1 | 676 | |
77c62063 | 677 | template<typename... _Types> |
678 | struct _Move_assign_base<true, _Types...> : _Copy_assign_alias<_Types...> | |
679 | { | |
680 | using _Base = _Copy_assign_alias<_Types...>; | |
681 | using _Base::_Base; | |
682 | }; | |
683 | ||
684 | template<typename... _Types> | |
685 | using _Move_assign_alias = | |
492debfa | 686 | _Move_assign_base<_Traits<_Types...>::_S_trivial_move_assign, _Types...>; |
77c62063 | 687 | |
688 | template<typename... _Types> | |
689 | struct _Variant_base : _Move_assign_alias<_Types...> | |
690 | { | |
691 | using _Base = _Move_assign_alias<_Types...>; | |
692 | ||
693 | constexpr | |
694 | _Variant_base() | |
ae6a4ce9 | 695 | noexcept(_Traits<_Types...>::_S_nothrow_default_ctor) |
77c62063 | 696 | : _Variant_base(in_place_index<0>) { } |
697 | ||
698 | template<size_t _Np, typename... _Args> | |
699 | constexpr explicit | |
700 | _Variant_base(in_place_index_t<_Np> __i, _Args&&... __args) | |
701 | : _Base(__i, std::forward<_Args>(__args)...) | |
702 | { } | |
703 | ||
704 | _Variant_base(const _Variant_base&) = default; | |
705 | _Variant_base(_Variant_base&&) = default; | |
706 | _Variant_base& operator=(const _Variant_base&) = default; | |
707 | _Variant_base& operator=(_Variant_base&&) = default; | |
85adbce1 | 708 | }; |
709 | ||
710 | // For how many times does _Tp appear in _Tuple? | |
711 | template<typename _Tp, typename _Tuple> | |
712 | struct __tuple_count; | |
713 | ||
714 | template<typename _Tp, typename _Tuple> | |
b5492afc | 715 | inline constexpr size_t __tuple_count_v = |
716 | __tuple_count<_Tp, _Tuple>::value; | |
85adbce1 | 717 | |
718 | template<typename _Tp, typename... _Types> | |
719 | struct __tuple_count<_Tp, tuple<_Types...>> | |
720 | : integral_constant<size_t, 0> { }; | |
721 | ||
722 | template<typename _Tp, typename _First, typename... _Rest> | |
723 | struct __tuple_count<_Tp, tuple<_First, _Rest...>> | |
724 | : integral_constant< | |
725 | size_t, | |
726 | __tuple_count_v<_Tp, tuple<_Rest...>> + is_same_v<_Tp, _First>> { }; | |
727 | ||
728 | // TODO: Reuse this in <tuple> ? | |
729 | template<typename _Tp, typename... _Types> | |
b5492afc | 730 | inline constexpr bool __exactly_once = |
731 | __tuple_count_v<_Tp, tuple<_Types...>> == 1; | |
85adbce1 | 732 | |
733 | // Takes _Types and create an overloaded _S_fun for each type. | |
734 | // If a type appears more than once in _Types, create only one overload. | |
735 | template<typename... _Types> | |
736 | struct __overload_set | |
737 | { static void _S_fun(); }; | |
738 | ||
739 | template<typename _First, typename... _Rest> | |
740 | struct __overload_set<_First, _Rest...> : __overload_set<_Rest...> | |
741 | { | |
742 | using __overload_set<_Rest...>::_S_fun; | |
743 | static integral_constant<size_t, sizeof...(_Rest)> _S_fun(_First); | |
744 | }; | |
745 | ||
746 | template<typename... _Rest> | |
747 | struct __overload_set<void, _Rest...> : __overload_set<_Rest...> | |
748 | { | |
749 | using __overload_set<_Rest...>::_S_fun; | |
750 | }; | |
751 | ||
752 | // Helper for variant(_Tp&&) and variant::operator=(_Tp&&). | |
6dd97553 | 753 | // __accepted_index maps an arbitrary _Tp to an alternative type in _Variant |
754 | // (or to variant_npos). | |
85adbce1 | 755 | template<typename _Tp, typename _Variant, typename = void> |
756 | struct __accepted_index | |
757 | { static constexpr size_t value = variant_npos; }; | |
758 | ||
759 | template<typename _Tp, typename... _Types> | |
760 | struct __accepted_index< | |
761 | _Tp, variant<_Types...>, | |
6dd97553 | 762 | void_t<decltype(__overload_set<_Types...>::_S_fun(std::declval<_Tp>()))>> |
85adbce1 | 763 | { |
764 | static constexpr size_t value = sizeof...(_Types) - 1 | |
765 | - decltype(__overload_set<_Types...>:: | |
766 | _S_fun(std::declval<_Tp>()))::value; | |
767 | }; | |
768 | ||
769 | // Returns the raw storage for __v. | |
770 | template<typename _Variant> | |
5c6334a5 | 771 | void* __get_storage(_Variant&& __v) noexcept |
85adbce1 | 772 | { return __v._M_storage(); } |
773 | ||
4c0ef551 | 774 | template <typename _Maybe_variant_cookie, typename _Variant> |
781cb64d | 775 | struct _Extra_visit_slot_needed |
776 | { | |
777 | template <typename> struct _Variant_never_valueless; | |
4c0ef551 | 778 | |
781cb64d | 779 | template <typename... _Types> |
780 | struct _Variant_never_valueless<variant<_Types...>> | |
781 | : bool_constant<__never_valueless<_Types...>()> {}; | |
4c0ef551 | 782 | |
781cb64d | 783 | static constexpr bool value = |
784 | (is_same_v<_Maybe_variant_cookie, __variant_cookie> | |
785 | || is_same_v<_Maybe_variant_cookie, __variant_idx_cookie>) | |
786 | && !_Variant_never_valueless<__remove_cvref_t<_Variant>>::value; | |
787 | }; | |
4c0ef551 | 788 | |
492debfa | 789 | // Used for storing a multi-dimensional vtable. |
85adbce1 | 790 | template<typename _Tp, size_t... _Dimensions> |
492debfa | 791 | struct _Multi_array; |
792 | ||
793 | // Partial specialization with rank zero, stores a single _Tp element. | |
794 | template<typename _Tp> | |
795 | struct _Multi_array<_Tp> | |
85adbce1 | 796 | { |
f03f26fa | 797 | template<typename> |
798 | struct __untag_result | |
799 | : false_type | |
800 | { using element_type = _Tp; }; | |
801 | ||
802 | template <typename... _Args> | |
803 | struct __untag_result<const void(*)(_Args...)> | |
804 | : false_type | |
805 | { using element_type = void(*)(_Args...); }; | |
806 | ||
807 | template <typename... _Args> | |
808 | struct __untag_result<__variant_cookie(*)(_Args...)> | |
809 | : false_type | |
810 | { using element_type = void(*)(_Args...); }; | |
811 | ||
812 | template <typename... _Args> | |
813 | struct __untag_result<__variant_idx_cookie(*)(_Args...)> | |
814 | : false_type | |
815 | { using element_type = void(*)(_Args...); }; | |
816 | ||
817 | template <typename _Res, typename... _Args> | |
818 | struct __untag_result<__deduce_visit_result<_Res>(*)(_Args...)> | |
819 | : true_type | |
820 | { using element_type = _Res(*)(_Args...); }; | |
821 | ||
822 | using __result_is_deduced = __untag_result<_Tp>; | |
823 | ||
824 | constexpr const typename __untag_result<_Tp>::element_type& | |
85adbce1 | 825 | _M_access() const |
826 | { return _M_data; } | |
827 | ||
f03f26fa | 828 | typename __untag_result<_Tp>::element_type _M_data; |
85adbce1 | 829 | }; |
830 | ||
492debfa | 831 | // Partial specialization with rank >= 1. |
49c83dca | 832 | template<typename _Ret, |
833 | typename _Visitor, | |
834 | typename... _Variants, | |
835 | size_t __first, size_t... __rest> | |
836 | struct _Multi_array<_Ret(*)(_Visitor, _Variants...), __first, __rest...> | |
85adbce1 | 837 | { |
4c0ef551 | 838 | static constexpr size_t __index = |
839 | sizeof...(_Variants) - sizeof...(__rest) - 1; | |
492debfa | 840 | |
4c0ef551 | 841 | using _Variant = typename _Nth_type<__index, _Variants...>::type; |
492debfa | 842 | |
49c83dca | 843 | static constexpr int __do_cookie = |
4c0ef551 | 844 | _Extra_visit_slot_needed<_Ret, _Variant>::value ? 1 : 0; |
492debfa | 845 | |
49c83dca | 846 | using _Tp = _Ret(*)(_Visitor, _Variants...); |
492debfa | 847 | |
85adbce1 | 848 | template<typename... _Args> |
f03f26fa | 849 | constexpr decltype(auto) |
85adbce1 | 850 | _M_access(size_t __first_index, _Args... __rest_indices) const |
492debfa | 851 | { |
852 | return _M_arr[__first_index + __do_cookie] | |
853 | ._M_access(__rest_indices...); | |
854 | } | |
85adbce1 | 855 | |
49c83dca | 856 | _Multi_array<_Tp, __rest...> _M_arr[__first + __do_cookie]; |
85adbce1 | 857 | }; |
858 | ||
859 | // Creates a multi-dimensional vtable recursively. | |
85adbce1 | 860 | // |
861 | // For example, | |
862 | // visit([](auto, auto){}, | |
2a5d61f9 | 863 | // variant<int, char>(), // typedef'ed as V1 |
864 | // variant<float, double, long double>()) // typedef'ed as V2 | |
85adbce1 | 865 | // will trigger instantiations of: |
f03f26fa | 866 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 2, 3>, |
2a5d61f9 | 867 | // tuple<V1&&, V2&&>, std::index_sequence<>> |
f03f26fa | 868 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 3>, |
2a5d61f9 | 869 | // tuple<V1&&, V2&&>, std::index_sequence<0>> |
f03f26fa | 870 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
2a5d61f9 | 871 | // tuple<V1&&, V2&&>, std::index_sequence<0, 0>> |
f03f26fa | 872 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
2a5d61f9 | 873 | // tuple<V1&&, V2&&>, std::index_sequence<0, 1>> |
f03f26fa | 874 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
2a5d61f9 | 875 | // tuple<V1&&, V2&&>, std::index_sequence<0, 2>> |
f03f26fa | 876 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&), 3>, |
2a5d61f9 | 877 | // tuple<V1&&, V2&&>, std::index_sequence<1>> |
f03f26fa | 878 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
2a5d61f9 | 879 | // tuple<V1&&, V2&&>, std::index_sequence<1, 0>> |
f03f26fa | 880 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
2a5d61f9 | 881 | // tuple<V1&&, V2&&>, std::index_sequence<1, 1>> |
f03f26fa | 882 | // __gen_vtable_impl<_Multi_array<void(*)(V1&&, V2&&)>, |
2a5d61f9 | 883 | // tuple<V1&&, V2&&>, std::index_sequence<1, 2>> |
85adbce1 | 884 | // The returned multi-dimensional vtable can be fast accessed by the visitor |
885 | // using index calculation. | |
f03f26fa | 886 | template<typename _Array_type, typename _Index_seq> |
85adbce1 | 887 | struct __gen_vtable_impl; |
888 | ||
492debfa | 889 | // Defines the _S_apply() member that returns a _Multi_array populated |
890 | // with function pointers that perform the visitation expressions e(m) | |
891 | // for each valid pack of indexes into the variant types _Variants. | |
892 | // | |
893 | // This partial specialization builds up the index sequences by recursively | |
894 | // calling _S_apply() on the next specialization of __gen_vtable_impl. | |
895 | // The base case of the recursion defines the actual function pointers. | |
f03f26fa | 896 | template<typename _Result_type, typename _Visitor, size_t... __dimensions, |
2a5d61f9 | 897 | typename... _Variants, size_t... __indices> |
898 | struct __gen_vtable_impl< | |
a4e92d65 | 899 | _Multi_array<_Result_type (*)(_Visitor, _Variants...), __dimensions...>, |
f03f26fa | 900 | std::index_sequence<__indices...>> |
85adbce1 | 901 | { |
2a5d61f9 | 902 | using _Next = |
903 | remove_reference_t<typename _Nth_type<sizeof...(__indices), | |
904 | _Variants...>::type>; | |
905 | using _Array_type = | |
a4e92d65 | 906 | _Multi_array<_Result_type (*)(_Visitor, _Variants...), |
907 | __dimensions...>; | |
2a5d61f9 | 908 | |
85adbce1 | 909 | static constexpr _Array_type |
910 | _S_apply() | |
911 | { | |
912 | _Array_type __vtable{}; | |
913 | _S_apply_all_alts( | |
2a5d61f9 | 914 | __vtable, make_index_sequence<variant_size_v<_Next>>()); |
85adbce1 | 915 | return __vtable; |
916 | } | |
917 | ||
2a5d61f9 | 918 | template<size_t... __var_indices> |
85adbce1 | 919 | static constexpr void |
2a5d61f9 | 920 | _S_apply_all_alts(_Array_type& __vtable, |
921 | std::index_sequence<__var_indices...>) | |
922 | { | |
4c0ef551 | 923 | if constexpr (_Extra_visit_slot_needed<_Result_type, _Next>::value) |
49c83dca | 924 | (_S_apply_single_alt<true, __var_indices>( |
925 | __vtable._M_arr[__var_indices + 1], | |
926 | &(__vtable._M_arr[0])), ...); | |
927 | else | |
928 | (_S_apply_single_alt<false, __var_indices>( | |
929 | __vtable._M_arr[__var_indices]), ...); | |
2a5d61f9 | 930 | } |
85adbce1 | 931 | |
49c83dca | 932 | template<bool __do_cookie, size_t __index, typename _Tp> |
85adbce1 | 933 | static constexpr void |
49c83dca | 934 | _S_apply_single_alt(_Tp& __element, _Tp* __cookie_element = nullptr) |
85adbce1 | 935 | { |
49c83dca | 936 | if constexpr (__do_cookie) |
937 | { | |
938 | __element = __gen_vtable_impl< | |
939 | _Tp, | |
49c83dca | 940 | std::index_sequence<__indices..., __index>>::_S_apply(); |
941 | *__cookie_element = __gen_vtable_impl< | |
942 | _Tp, | |
49c83dca | 943 | std::index_sequence<__indices..., variant_npos>>::_S_apply(); |
944 | } | |
945 | else | |
946 | { | |
947 | __element = __gen_vtable_impl< | |
f03f26fa | 948 | remove_reference_t<decltype(__element)>, |
49c83dca | 949 | std::index_sequence<__indices..., __index>>::_S_apply(); |
950 | } | |
85adbce1 | 951 | } |
952 | }; | |
953 | ||
492debfa | 954 | // This partial specialization is the base case for the recursion. |
955 | // It populates a _Multi_array element with the address of a function | |
956 | // that invokes the visitor with the alternatives specified by __indices. | |
f03f26fa | 957 | template<typename _Result_type, typename _Visitor, typename... _Variants, |
2a5d61f9 | 958 | size_t... __indices> |
85adbce1 | 959 | struct __gen_vtable_impl< |
2a5d61f9 | 960 | _Multi_array<_Result_type (*)(_Visitor, _Variants...)>, |
f03f26fa | 961 | std::index_sequence<__indices...>> |
85adbce1 | 962 | { |
963 | using _Array_type = | |
492debfa | 964 | _Multi_array<_Result_type (*)(_Visitor, _Variants...)>; |
2a5d61f9 | 965 | |
49c83dca | 966 | template<size_t __index, typename _Variant> |
967 | static constexpr decltype(auto) | |
e11f5aed | 968 | __element_by_index_or_cookie(_Variant&& __var) noexcept |
49c83dca | 969 | { |
970 | if constexpr (__index != variant_npos) | |
971 | return __variant::__get<__index>(std::forward<_Variant>(__var)); | |
972 | else | |
973 | return __variant_cookie{}; | |
974 | } | |
975 | ||
4429133c | 976 | static constexpr decltype(auto) |
f03f26fa | 977 | __visit_invoke(_Visitor&& __visitor, _Variants... __vars) |
2a5d61f9 | 978 | { |
492debfa | 979 | if constexpr (is_same_v<_Result_type, __variant_idx_cookie>) |
f03f26fa | 980 | // For raw visitation using indices, pass the indices to the visitor |
981 | // and discard the return value: | |
982 | std::__invoke(std::forward<_Visitor>(__visitor), | |
492debfa | 983 | __element_by_index_or_cookie<__indices>( |
984 | std::forward<_Variants>(__vars))..., | |
985 | integral_constant<size_t, __indices>()...); | |
f03f26fa | 986 | else if constexpr (is_same_v<_Result_type, __variant_cookie>) |
987 | // For raw visitation without indices, and discard the return value: | |
988 | std::__invoke(std::forward<_Visitor>(__visitor), | |
492debfa | 989 | __element_by_index_or_cookie<__indices>( |
990 | std::forward<_Variants>(__vars))...); | |
f03f26fa | 991 | else if constexpr (_Array_type::__result_is_deduced::value) |
992 | // For the usual std::visit case deduce the return value: | |
4f3e024d | 993 | return std::__invoke(std::forward<_Visitor>(__visitor), |
492debfa | 994 | __element_by_index_or_cookie<__indices>( |
995 | std::forward<_Variants>(__vars))...); | |
f03f26fa | 996 | else // for std::visit<R> use INVOKE<R> |
997 | return std::__invoke_r<_Result_type>( | |
998 | std::forward<_Visitor>(__visitor), | |
999 | __variant::__get<__indices>(std::forward<_Variants>(__vars))...); | |
ff7d433d | 1000 | } |
1001 | ||
85adbce1 | 1002 | static constexpr auto |
1003 | _S_apply() | |
2a5d61f9 | 1004 | { return _Array_type{&__visit_invoke}; } |
85adbce1 | 1005 | }; |
1006 | ||
f03f26fa | 1007 | template<typename _Result_type, typename _Visitor, typename... _Variants> |
85adbce1 | 1008 | struct __gen_vtable |
1009 | { | |
85adbce1 | 1010 | using _Array_type = |
492debfa | 1011 | _Multi_array<_Result_type (*)(_Visitor, _Variants...), |
28b460dd | 1012 | variant_size_v<remove_reference_t<_Variants>>...>; |
85adbce1 | 1013 | |
492debfa | 1014 | static constexpr _Array_type _S_vtable |
f03f26fa | 1015 | = __gen_vtable_impl<_Array_type, std::index_sequence<>>::_S_apply(); |
85adbce1 | 1016 | }; |
1017 | ||
a6787bda | 1018 | template<size_t _Np, typename _Tp> |
1019 | struct _Base_dedup : public _Tp { }; | |
1020 | ||
1021 | template<typename _Variant, typename __indices> | |
1022 | struct _Variant_hash_base; | |
1023 | ||
1024 | template<typename... _Types, size_t... __indices> | |
1025 | struct _Variant_hash_base<variant<_Types...>, | |
1026 | std::index_sequence<__indices...>> | |
1027 | : _Base_dedup<__indices, __poison_hash<remove_const_t<_Types>>>... { }; | |
1028 | ||
85adbce1 | 1029 | } // namespace __variant |
1030 | } // namespace __detail | |
1031 | ||
49c83dca | 1032 | template<size_t _Np, typename _Variant, typename... _Args> |
1033 | void __variant_construct_by_index(_Variant& __v, _Args&&... __args) | |
1034 | { | |
1035 | __v._M_index = _Np; | |
1036 | auto&& __storage = __detail::__variant::__get<_Np>(__v); | |
1037 | ::new ((void*)std::addressof(__storage)) | |
1038 | remove_reference_t<decltype(__storage)> | |
1039 | (std::forward<_Args>(__args)...); | |
1040 | } | |
1041 | ||
85adbce1 | 1042 | template<typename _Tp, typename... _Types> |
4429133c | 1043 | constexpr bool |
1044 | holds_alternative(const variant<_Types...>& __v) noexcept | |
85adbce1 | 1045 | { |
1046 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
1047 | "T should occur for exactly once in alternatives"); | |
1048 | return __v.index() == __detail::__variant::__index_of_v<_Tp, _Types...>; | |
1049 | } | |
1050 | ||
85adbce1 | 1051 | template<typename _Tp, typename... _Types> |
4429133c | 1052 | constexpr _Tp& get(variant<_Types...>& __v) |
85adbce1 | 1053 | { |
1054 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
1055 | "T should occur for exactly once in alternatives"); | |
1056 | static_assert(!is_void_v<_Tp>, "_Tp should not be void"); | |
4a12299e | 1057 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v); |
85adbce1 | 1058 | } |
1059 | ||
1060 | template<typename _Tp, typename... _Types> | |
4429133c | 1061 | constexpr _Tp&& get(variant<_Types...>&& __v) |
85adbce1 | 1062 | { |
1063 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
1064 | "T should occur for exactly once in alternatives"); | |
1065 | static_assert(!is_void_v<_Tp>, "_Tp should not be void"); | |
4a12299e | 1066 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>( |
85adbce1 | 1067 | std::move(__v)); |
1068 | } | |
1069 | ||
1070 | template<typename _Tp, typename... _Types> | |
4429133c | 1071 | constexpr const _Tp& get(const variant<_Types...>& __v) |
85adbce1 | 1072 | { |
1073 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
1074 | "T should occur for exactly once in alternatives"); | |
1075 | static_assert(!is_void_v<_Tp>, "_Tp should not be void"); | |
4a12299e | 1076 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>(__v); |
85adbce1 | 1077 | } |
1078 | ||
1079 | template<typename _Tp, typename... _Types> | |
4429133c | 1080 | constexpr const _Tp&& get(const variant<_Types...>&& __v) |
85adbce1 | 1081 | { |
1082 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
1083 | "T should occur for exactly once in alternatives"); | |
1084 | static_assert(!is_void_v<_Tp>, "_Tp should not be void"); | |
4a12299e | 1085 | return std::get<__detail::__variant::__index_of_v<_Tp, _Types...>>( |
85adbce1 | 1086 | std::move(__v)); |
1087 | } | |
1088 | ||
1089 | template<size_t _Np, typename... _Types> | |
4429133c | 1090 | constexpr add_pointer_t<variant_alternative_t<_Np, variant<_Types...>>> |
85adbce1 | 1091 | get_if(variant<_Types...>* __ptr) noexcept |
1092 | { | |
1093 | using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>; | |
1094 | static_assert(_Np < sizeof...(_Types), | |
1095 | "The index should be in [0, number of alternatives)"); | |
1096 | static_assert(!is_void_v<_Alternative_type>, "_Tp should not be void"); | |
1097 | if (__ptr && __ptr->index() == _Np) | |
49c83dca | 1098 | return std::addressof(__detail::__variant::__get<_Np>(*__ptr)); |
85adbce1 | 1099 | return nullptr; |
1100 | } | |
1101 | ||
1102 | template<size_t _Np, typename... _Types> | |
4429133c | 1103 | constexpr |
caaaa8fd | 1104 | add_pointer_t<const variant_alternative_t<_Np, variant<_Types...>>> |
85adbce1 | 1105 | get_if(const variant<_Types...>* __ptr) noexcept |
1106 | { | |
1107 | using _Alternative_type = variant_alternative_t<_Np, variant<_Types...>>; | |
1108 | static_assert(_Np < sizeof...(_Types), | |
1109 | "The index should be in [0, number of alternatives)"); | |
1110 | static_assert(!is_void_v<_Alternative_type>, "_Tp should not be void"); | |
1111 | if (__ptr && __ptr->index() == _Np) | |
49c83dca | 1112 | return std::addressof(__detail::__variant::__get<_Np>(*__ptr)); |
85adbce1 | 1113 | return nullptr; |
1114 | } | |
1115 | ||
1116 | template<typename _Tp, typename... _Types> | |
4429133c | 1117 | constexpr add_pointer_t<_Tp> |
caaaa8fd | 1118 | get_if(variant<_Types...>* __ptr) noexcept |
85adbce1 | 1119 | { |
1120 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
1121 | "T should occur for exactly once in alternatives"); | |
1122 | static_assert(!is_void_v<_Tp>, "_Tp should not be void"); | |
4a12299e | 1123 | return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>( |
1124 | __ptr); | |
85adbce1 | 1125 | } |
1126 | ||
1127 | template<typename _Tp, typename... _Types> | |
4429133c | 1128 | constexpr add_pointer_t<const _Tp> |
e11f5aed | 1129 | get_if(const variant<_Types...>* __ptr) noexcept |
85adbce1 | 1130 | { |
1131 | static_assert(__detail::__variant::__exactly_once<_Tp, _Types...>, | |
1132 | "T should occur for exactly once in alternatives"); | |
1133 | static_assert(!is_void_v<_Tp>, "_Tp should not be void"); | |
4a12299e | 1134 | return std::get_if<__detail::__variant::__index_of_v<_Tp, _Types...>>( |
1135 | __ptr); | |
85adbce1 | 1136 | } |
1137 | ||
824ecf42 | 1138 | struct monostate { }; |
85adbce1 | 1139 | |
824ecf42 | 1140 | #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP, __NAME) \ |
1141 | template<typename... _Types> \ | |
1142 | constexpr bool operator __OP(const variant<_Types...>& __lhs, \ | |
1143 | const variant<_Types...>& __rhs) \ | |
1144 | { \ | |
49c83dca | 1145 | bool __ret = true; \ |
f03f26fa | 1146 | __detail::__variant::__raw_idx_visit( \ |
1147 | [&__ret, &__lhs] (auto&& __rhs_mem, auto __rhs_index) mutable \ | |
49c83dca | 1148 | { \ |
4f3e024d | 1149 | if constexpr (__rhs_index != variant_npos) \ |
1150 | { \ | |
1151 | if (__lhs.index() == __rhs_index) \ | |
1152 | { \ | |
1153 | auto& __this_mem = std::get<__rhs_index>(__lhs); \ | |
1154 | __ret = __this_mem __OP __rhs_mem; \ | |
1155 | } \ | |
1156 | else \ | |
1157 | __ret = (__lhs.index() + 1) __OP (__rhs_index + 1); \ | |
1158 | } \ | |
1159 | else \ | |
1160 | __ret = (__lhs.index() + 1) __OP (__rhs_index + 1); \ | |
4f3e024d | 1161 | }, __rhs); \ |
49c83dca | 1162 | return __ret; \ |
824ecf42 | 1163 | } \ |
1164 | \ | |
1165 | constexpr bool operator __OP(monostate, monostate) noexcept \ | |
1166 | { return 0 __OP 0; } | |
1167 | ||
1168 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<, less) | |
1169 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<=, less_equal) | |
1170 | _VARIANT_RELATION_FUNCTION_TEMPLATE(==, equal) | |
1171 | _VARIANT_RELATION_FUNCTION_TEMPLATE(!=, not_equal) | |
1172 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>=, greater_equal) | |
1173 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>, greater) | |
1174 | ||
1175 | #undef _VARIANT_RELATION_FUNCTION_TEMPLATE | |
85adbce1 | 1176 | |
1177 | template<typename _Visitor, typename... _Variants> | |
2a5d61f9 | 1178 | constexpr decltype(auto) visit(_Visitor&&, _Variants&&...); |
85adbce1 | 1179 | |
85adbce1 | 1180 | template<typename... _Types> |
a6787bda | 1181 | inline enable_if_t<(is_move_constructible_v<_Types> && ...) |
1182 | && (is_swappable_v<_Types> && ...)> | |
f89b61dd | 1183 | swap(variant<_Types...>& __lhs, variant<_Types...>& __rhs) |
1184 | noexcept(noexcept(__lhs.swap(__rhs))) | |
85adbce1 | 1185 | { __lhs.swap(__rhs); } |
1186 | ||
f89b61dd | 1187 | template<typename... _Types> |
fd1c8642 | 1188 | enable_if_t<!((is_move_constructible_v<_Types> && ...) |
1189 | && (is_swappable_v<_Types> && ...))> | |
f89b61dd | 1190 | swap(variant<_Types...>&, variant<_Types...>&) = delete; |
1191 | ||
85adbce1 | 1192 | class bad_variant_access : public exception |
1193 | { | |
1194 | public: | |
1195 | bad_variant_access() noexcept : _M_reason("Unknown reason") { } | |
1196 | const char* what() const noexcept override | |
1197 | { return _M_reason; } | |
1198 | ||
1199 | private: | |
1200 | bad_variant_access(const char* __reason) : _M_reason(__reason) { } | |
1201 | ||
1202 | const char* _M_reason; | |
1203 | ||
1204 | friend void __throw_bad_variant_access(const char* __what); | |
1205 | }; | |
1206 | ||
1207 | inline void | |
1208 | __throw_bad_variant_access(const char* __what) | |
1209 | { _GLIBCXX_THROW_OR_ABORT(bad_variant_access(__what)); } | |
1210 | ||
1211 | template<typename... _Types> | |
1212 | class variant | |
1213 | : private __detail::__variant::_Variant_base<_Types...>, | |
1214 | private _Enable_default_constructor< | |
ae6a4ce9 | 1215 | __detail::__variant::_Traits<_Types...>::_S_default_ctor, |
77c62063 | 1216 | variant<_Types...>>, |
85adbce1 | 1217 | private _Enable_copy_move< |
ae6a4ce9 | 1218 | __detail::__variant::_Traits<_Types...>::_S_copy_ctor, |
1219 | __detail::__variant::_Traits<_Types...>::_S_copy_assign, | |
1220 | __detail::__variant::_Traits<_Types...>::_S_move_ctor, | |
1221 | __detail::__variant::_Traits<_Types...>::_S_move_assign, | |
85adbce1 | 1222 | variant<_Types...>> |
1223 | { | |
1224 | private: | |
49c83dca | 1225 | template <typename... _UTypes, typename _Tp> |
1226 | friend decltype(auto) __variant_cast(_Tp&&); | |
1227 | template<size_t _Np, typename _Variant, typename... _Args> | |
1228 | friend void __variant_construct_by_index(_Variant& __v, | |
1229 | _Args&&... __args); | |
1230 | ||
f24f2a9e | 1231 | static_assert(sizeof...(_Types) > 0, |
1232 | "variant must have at least one alternative"); | |
1233 | static_assert(!(std::is_reference_v<_Types> || ...), | |
1234 | "variant must have no reference alternative"); | |
1235 | static_assert(!(std::is_void_v<_Types> || ...), | |
1236 | "variant must have no void alternative"); | |
1237 | ||
85adbce1 | 1238 | using _Base = __detail::__variant::_Variant_base<_Types...>; |
1239 | using _Default_ctor_enabler = | |
ae6a4ce9 | 1240 | _Enable_default_constructor< |
1241 | __detail::__variant::_Traits<_Types...>::_S_default_ctor, | |
1242 | variant<_Types...>>; | |
85adbce1 | 1243 | |
28cc38ec | 1244 | template<typename _Tp> |
1245 | static constexpr bool __not_self | |
1246 | = !is_same_v<__remove_cvref_t<_Tp>, variant>; | |
1247 | ||
85adbce1 | 1248 | template<typename _Tp> |
1249 | static constexpr bool | |
1250 | __exactly_once = __detail::__variant::__exactly_once<_Tp, _Types...>; | |
1251 | ||
1252 | template<typename _Tp> | |
1253 | static constexpr size_t __accepted_index = | |
1254 | __detail::__variant::__accepted_index<_Tp&&, variant>::value; | |
1255 | ||
28cc38ec | 1256 | template<size_t _Np, typename = enable_if_t<(_Np < sizeof...(_Types))>> |
1257 | using __to_type = variant_alternative_t<_Np, variant>; | |
85adbce1 | 1258 | |
28cc38ec | 1259 | template<typename _Tp, typename = enable_if_t<__not_self<_Tp>>> |
85adbce1 | 1260 | using __accepted_type = __to_type<__accepted_index<_Tp>>; |
1261 | ||
85adbce1 | 1262 | template<typename _Tp> |
1263 | static constexpr size_t __index_of = | |
1264 | __detail::__variant::__index_of_v<_Tp, _Types...>; | |
1265 | ||
77c62063 | 1266 | using _Traits = __detail::__variant::_Traits<_Types...>; |
1267 | ||
28cc38ec | 1268 | template<typename _Tp> |
1269 | struct __is_in_place_tag : false_type { }; | |
1270 | template<typename _Tp> | |
1271 | struct __is_in_place_tag<in_place_type_t<_Tp>> : true_type { }; | |
1272 | template<size_t _Np> | |
1273 | struct __is_in_place_tag<in_place_index_t<_Np>> : true_type { }; | |
1274 | ||
1275 | template<typename _Tp> | |
1276 | static constexpr bool __not_in_place_tag | |
1277 | = !__is_in_place_tag<__remove_cvref_t<_Tp>>::value; | |
1278 | ||
85adbce1 | 1279 | public: |
77c62063 | 1280 | variant() = default; |
1281 | variant(const variant& __rhs) = default; | |
1282 | variant(variant&&) = default; | |
1283 | variant& operator=(const variant&) = default; | |
1284 | variant& operator=(variant&&) = default; | |
1285 | ~variant() = default; | |
85adbce1 | 1286 | |
1287 | template<typename _Tp, | |
28cc38ec | 1288 | typename = enable_if_t<sizeof...(_Types) != 0>, |
1289 | typename = enable_if_t<__not_in_place_tag<_Tp>>, | |
1290 | typename _Tj = __accepted_type<_Tp&&>, | |
1291 | typename = enable_if_t<__exactly_once<_Tj> | |
1292 | && is_constructible_v<_Tj, _Tp>>> | |
85adbce1 | 1293 | constexpr |
1294 | variant(_Tp&& __t) | |
28cc38ec | 1295 | noexcept(is_nothrow_constructible_v<_Tj, _Tp>) |
77c62063 | 1296 | : variant(in_place_index<__accepted_index<_Tp&&>>, |
ae6a4ce9 | 1297 | std::forward<_Tp>(__t)) |
e1d699b8 | 1298 | { } |
85adbce1 | 1299 | |
1300 | template<typename _Tp, typename... _Args, | |
1301 | typename = enable_if_t<__exactly_once<_Tp> | |
28cc38ec | 1302 | && is_constructible_v<_Tp, _Args...>>> |
85adbce1 | 1303 | constexpr explicit |
1304 | variant(in_place_type_t<_Tp>, _Args&&... __args) | |
77c62063 | 1305 | : variant(in_place_index<__index_of<_Tp>>, |
ae6a4ce9 | 1306 | std::forward<_Args>(__args)...) |
e1d699b8 | 1307 | { } |
85adbce1 | 1308 | |
1309 | template<typename _Tp, typename _Up, typename... _Args, | |
1310 | typename = enable_if_t<__exactly_once<_Tp> | |
28cc38ec | 1311 | && is_constructible_v<_Tp, |
1312 | initializer_list<_Up>&, _Args...>>> | |
85adbce1 | 1313 | constexpr explicit |
1314 | variant(in_place_type_t<_Tp>, initializer_list<_Up> __il, | |
1315 | _Args&&... __args) | |
ee6c971a | 1316 | : variant(in_place_index<__index_of<_Tp>>, __il, |
4d1e18aa | 1317 | std::forward<_Args>(__args)...) |
e1d699b8 | 1318 | { } |
85adbce1 | 1319 | |
1320 | template<size_t _Np, typename... _Args, | |
28cc38ec | 1321 | typename _Tp = __to_type<_Np>, |
1322 | typename = enable_if_t<is_constructible_v<_Tp, _Args...>>> | |
85adbce1 | 1323 | constexpr explicit |
1324 | variant(in_place_index_t<_Np>, _Args&&... __args) | |
ee6c971a | 1325 | : _Base(in_place_index<_Np>, std::forward<_Args>(__args)...), |
85adbce1 | 1326 | _Default_ctor_enabler(_Enable_default_constructor_tag{}) |
e1d699b8 | 1327 | { } |
85adbce1 | 1328 | |
1329 | template<size_t _Np, typename _Up, typename... _Args, | |
28cc38ec | 1330 | typename _Tp = __to_type<_Np>, |
1331 | typename = enable_if_t<is_constructible_v<_Tp, | |
1332 | initializer_list<_Up>&, | |
1333 | _Args...>>> | |
85adbce1 | 1334 | constexpr explicit |
1335 | variant(in_place_index_t<_Np>, initializer_list<_Up> __il, | |
1336 | _Args&&... __args) | |
ee6c971a | 1337 | : _Base(in_place_index<_Np>, __il, std::forward<_Args>(__args)...), |
85adbce1 | 1338 | _Default_ctor_enabler(_Enable_default_constructor_tag{}) |
e1d699b8 | 1339 | { } |
85adbce1 | 1340 | |
85adbce1 | 1341 | template<typename _Tp> |
1342 | enable_if_t<__exactly_once<__accepted_type<_Tp&&>> | |
28cc38ec | 1343 | && is_constructible_v<__accepted_type<_Tp&&>, _Tp> |
1344 | && is_assignable_v<__accepted_type<_Tp&&>&, _Tp>, | |
1345 | variant&> | |
85adbce1 | 1346 | operator=(_Tp&& __rhs) |
28cc38ec | 1347 | noexcept(is_nothrow_assignable_v<__accepted_type<_Tp&&>&, _Tp> |
1348 | && is_nothrow_constructible_v<__accepted_type<_Tp&&>, _Tp>) | |
85adbce1 | 1349 | { |
1350 | constexpr auto __index = __accepted_index<_Tp&&>; | |
1351 | if (index() == __index) | |
4e820860 | 1352 | std::get<__index>(*this) = std::forward<_Tp>(__rhs); |
85adbce1 | 1353 | else |
fd1863e1 | 1354 | { |
1355 | using _Tj = __accepted_type<_Tp&&>; | |
1356 | if constexpr (is_nothrow_constructible_v<_Tj, _Tp> | |
1357 | || !is_nothrow_move_constructible_v<_Tj>) | |
1358 | this->emplace<__index>(std::forward<_Tp>(__rhs)); | |
1359 | else | |
1360 | operator=(variant(std::forward<_Tp>(__rhs))); | |
1361 | } | |
85adbce1 | 1362 | return *this; |
1363 | } | |
1364 | ||
1365 | template<typename _Tp, typename... _Args> | |
87da0999 | 1366 | enable_if_t<is_constructible_v<_Tp, _Args...> && __exactly_once<_Tp>, |
1367 | _Tp&> | |
a6787bda | 1368 | emplace(_Args&&... __args) |
85adbce1 | 1369 | { |
e1d699b8 | 1370 | constexpr size_t __index = __index_of<_Tp>; |
1371 | return this->emplace<__index>(std::forward<_Args>(__args)...); | |
85adbce1 | 1372 | } |
1373 | ||
1374 | template<typename _Tp, typename _Up, typename... _Args> | |
a6787bda | 1375 | enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...> |
87da0999 | 1376 | && __exactly_once<_Tp>, |
1377 | _Tp&> | |
a6787bda | 1378 | emplace(initializer_list<_Up> __il, _Args&&... __args) |
85adbce1 | 1379 | { |
e1d699b8 | 1380 | constexpr size_t __index = __index_of<_Tp>; |
1381 | return this->emplace<__index>(__il, std::forward<_Args>(__args)...); | |
85adbce1 | 1382 | } |
1383 | ||
1384 | template<size_t _Np, typename... _Args> | |
a6787bda | 1385 | enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>, |
87da0999 | 1386 | _Args...>, |
1387 | variant_alternative_t<_Np, variant>&> | |
a6787bda | 1388 | emplace(_Args&&... __args) |
85adbce1 | 1389 | { |
1390 | static_assert(_Np < sizeof...(_Types), | |
1391 | "The index should be in [0, number of alternatives)"); | |
8815ac91 | 1392 | using type = variant_alternative_t<_Np, variant>; |
781cb64d | 1393 | // Provide the strong exception-safety guarantee when possible, |
1394 | // to avoid becoming valueless. | |
1395 | if constexpr (is_nothrow_constructible_v<type, _Args...>) | |
1396 | { | |
1397 | this->_M_reset(); | |
1398 | __variant_construct_by_index<_Np>(*this, | |
1399 | std::forward<_Args>(__args)...); | |
1400 | } | |
1401 | else if constexpr (is_scalar_v<type>) | |
8815ac91 | 1402 | { |
781cb64d | 1403 | // This might invoke a potentially-throwing conversion operator: |
1404 | const type __tmp(std::forward<_Args>(__args)...); | |
1405 | // But these steps won't throw: | |
1406 | this->_M_reset(); | |
1407 | __variant_construct_by_index<_Np>(*this, __tmp); | |
1408 | } | |
b9d8292f | 1409 | else if constexpr (__detail::__variant::_Never_valueless_alt<type>() |
1410 | && _Traits::_S_move_assign) | |
781cb64d | 1411 | { |
1412 | // This construction might throw: | |
8815ac91 | 1413 | variant __tmp(in_place_index<_Np>, |
1414 | std::forward<_Args>(__args)...); | |
781cb64d | 1415 | // But _Never_valueless_alt<type> means this won't: |
8815ac91 | 1416 | *this = std::move(__tmp); |
85adbce1 | 1417 | } |
781cb64d | 1418 | else |
85adbce1 | 1419 | { |
781cb64d | 1420 | // This case only provides the basic exception-safety guarantee, |
1421 | // i.e. the variant can become valueless. | |
1422 | this->_M_reset(); | |
1423 | __try | |
1424 | { | |
1425 | __variant_construct_by_index<_Np>(*this, | |
1426 | std::forward<_Args>(__args)...); | |
1427 | } | |
1428 | __catch (...) | |
1429 | { | |
1430 | this->_M_index = variant_npos; | |
1431 | __throw_exception_again; | |
1432 | } | |
85adbce1 | 1433 | } |
87da0999 | 1434 | return std::get<_Np>(*this); |
85adbce1 | 1435 | } |
1436 | ||
1437 | template<size_t _Np, typename _Up, typename... _Args> | |
a6787bda | 1438 | enable_if_t<is_constructible_v<variant_alternative_t<_Np, variant>, |
87da0999 | 1439 | initializer_list<_Up>&, _Args...>, |
1440 | variant_alternative_t<_Np, variant>&> | |
a6787bda | 1441 | emplace(initializer_list<_Up> __il, _Args&&... __args) |
85adbce1 | 1442 | { |
1443 | static_assert(_Np < sizeof...(_Types), | |
1444 | "The index should be in [0, number of alternatives)"); | |
8815ac91 | 1445 | using type = variant_alternative_t<_Np, variant>; |
781cb64d | 1446 | // Provide the strong exception-safety guarantee when possible, |
1447 | // to avoid becoming valueless. | |
1448 | if constexpr (is_nothrow_constructible_v<type, | |
1449 | initializer_list<_Up>&, | |
1450 | _Args...>) | |
8815ac91 | 1451 | { |
781cb64d | 1452 | this->_M_reset(); |
1453 | __variant_construct_by_index<_Np>(*this, __il, | |
1454 | std::forward<_Args>(__args)...); | |
1455 | } | |
b9d8292f | 1456 | else if constexpr (__detail::__variant::_Never_valueless_alt<type>() |
1457 | && _Traits::_S_move_assign) | |
781cb64d | 1458 | { |
1459 | // This construction might throw: | |
8815ac91 | 1460 | variant __tmp(in_place_index<_Np>, __il, |
1461 | std::forward<_Args>(__args)...); | |
781cb64d | 1462 | // But _Never_valueless_alt<type> means this won't: |
8815ac91 | 1463 | *this = std::move(__tmp); |
85adbce1 | 1464 | } |
781cb64d | 1465 | else |
85adbce1 | 1466 | { |
781cb64d | 1467 | // This case only provides the basic exception-safety guarantee, |
1468 | // i.e. the variant can become valueless. | |
1469 | this->_M_reset(); | |
1470 | __try | |
1471 | { | |
1472 | __variant_construct_by_index<_Np>(*this, __il, | |
1473 | std::forward<_Args>(__args)...); | |
1474 | } | |
1475 | __catch (...) | |
1476 | { | |
1477 | this->_M_index = variant_npos; | |
1478 | __throw_exception_again; | |
1479 | } | |
85adbce1 | 1480 | } |
87da0999 | 1481 | return std::get<_Np>(*this); |
85adbce1 | 1482 | } |
1483 | ||
1484 | constexpr bool valueless_by_exception() const noexcept | |
1485 | { return !this->_M_valid(); } | |
1486 | ||
1487 | constexpr size_t index() const noexcept | |
cfdb4aba | 1488 | { |
1489 | if (this->_M_index == | |
77c62063 | 1490 | typename _Base::__index_type(variant_npos)) |
cfdb4aba | 1491 | return variant_npos; |
1492 | return this->_M_index; | |
1493 | } | |
85adbce1 | 1494 | |
1495 | void | |
1496 | swap(variant& __rhs) | |
fd1c8642 | 1497 | noexcept((__is_nothrow_swappable<_Types>::value && ...) |
a6787bda | 1498 | && is_nothrow_move_constructible_v<variant>) |
85adbce1 | 1499 | { |
f03f26fa | 1500 | __detail::__variant::__raw_idx_visit( |
1501 | [this, &__rhs](auto&& __rhs_mem, auto __rhs_index) mutable | |
85adbce1 | 1502 | { |
4f3e024d | 1503 | if constexpr (__rhs_index != variant_npos) |
85adbce1 | 1504 | { |
4f3e024d | 1505 | if (this->index() == __rhs_index) |
49c83dca | 1506 | { |
4f3e024d | 1507 | auto& __this_mem = |
1508 | std::get<__rhs_index>(*this); | |
49c83dca | 1509 | using std::swap; |
1510 | swap(__this_mem, __rhs_mem); | |
1511 | } | |
4f3e024d | 1512 | else |
1513 | { | |
1514 | if (this->index() != variant_npos) | |
1515 | { | |
1516 | auto __tmp(std::move(__rhs_mem)); | |
1517 | __rhs = std::move(*this); | |
1518 | this->_M_destructive_move(__rhs_index, | |
1519 | std::move(__tmp)); | |
1520 | } | |
1521 | else | |
1522 | { | |
1523 | this->_M_destructive_move(__rhs_index, | |
1524 | std::move(__rhs_mem)); | |
1525 | __rhs._M_reset(); | |
1526 | } | |
1527 | } | |
85adbce1 | 1528 | } |
49c83dca | 1529 | else |
1530 | { | |
4f3e024d | 1531 | if (this->index() != variant_npos) |
49c83dca | 1532 | { |
4f3e024d | 1533 | __rhs = std::move(*this); |
49c83dca | 1534 | this->_M_reset(); |
1535 | } | |
49c83dca | 1536 | } |
4f3e024d | 1537 | }, __rhs); |
85adbce1 | 1538 | } |
1539 | ||
caaaa8fd | 1540 | private: |
caaaa8fd | 1541 | |
a9267d6a | 1542 | #if defined(__clang__) && __clang_major__ <= 7 |
a8f8d460 | 1543 | public: |
1544 | using _Base::_M_u; // See https://bugs.llvm.org/show_bug.cgi?id=31852 | |
1545 | private: | |
1546 | #endif | |
1547 | ||
caaaa8fd | 1548 | template<size_t _Np, typename _Vp> |
5c6334a5 | 1549 | friend constexpr decltype(auto) |
1550 | __detail::__variant::__get(_Vp&& __v) noexcept; | |
caaaa8fd | 1551 | |
85adbce1 | 1552 | template<typename _Vp> |
5c6334a5 | 1553 | friend void* |
1554 | __detail::__variant::__get_storage(_Vp&& __v) noexcept; | |
caaaa8fd | 1555 | |
824ecf42 | 1556 | #define _VARIANT_RELATION_FUNCTION_TEMPLATE(__OP) \ |
1557 | template<typename... _Tp> \ | |
1558 | friend constexpr bool \ | |
1559 | operator __OP(const variant<_Tp...>& __lhs, \ | |
1560 | const variant<_Tp...>& __rhs); | |
1561 | ||
1562 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<) | |
1563 | _VARIANT_RELATION_FUNCTION_TEMPLATE(<=) | |
1564 | _VARIANT_RELATION_FUNCTION_TEMPLATE(==) | |
1565 | _VARIANT_RELATION_FUNCTION_TEMPLATE(!=) | |
1566 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>=) | |
1567 | _VARIANT_RELATION_FUNCTION_TEMPLATE(>) | |
caaaa8fd | 1568 | |
824ecf42 | 1569 | #undef _VARIANT_RELATION_FUNCTION_TEMPLATE |
85adbce1 | 1570 | }; |
1571 | ||
85adbce1 | 1572 | template<size_t _Np, typename... _Types> |
caaaa8fd | 1573 | constexpr variant_alternative_t<_Np, variant<_Types...>>& |
85adbce1 | 1574 | get(variant<_Types...>& __v) |
1575 | { | |
1576 | static_assert(_Np < sizeof...(_Types), | |
1577 | "The index should be in [0, number of alternatives)"); | |
1578 | if (__v.index() != _Np) | |
1579 | __throw_bad_variant_access("Unexpected index"); | |
caaaa8fd | 1580 | return __detail::__variant::__get<_Np>(__v); |
85adbce1 | 1581 | } |
1582 | ||
1583 | template<size_t _Np, typename... _Types> | |
caaaa8fd | 1584 | constexpr variant_alternative_t<_Np, variant<_Types...>>&& |
85adbce1 | 1585 | get(variant<_Types...>&& __v) |
1586 | { | |
1587 | static_assert(_Np < sizeof...(_Types), | |
1588 | "The index should be in [0, number of alternatives)"); | |
1589 | if (__v.index() != _Np) | |
1590 | __throw_bad_variant_access("Unexpected index"); | |
caaaa8fd | 1591 | return __detail::__variant::__get<_Np>(std::move(__v)); |
85adbce1 | 1592 | } |
1593 | ||
1594 | template<size_t _Np, typename... _Types> | |
caaaa8fd | 1595 | constexpr const variant_alternative_t<_Np, variant<_Types...>>& |
85adbce1 | 1596 | get(const variant<_Types...>& __v) |
1597 | { | |
1598 | static_assert(_Np < sizeof...(_Types), | |
1599 | "The index should be in [0, number of alternatives)"); | |
1600 | if (__v.index() != _Np) | |
1601 | __throw_bad_variant_access("Unexpected index"); | |
caaaa8fd | 1602 | return __detail::__variant::__get<_Np>(__v); |
85adbce1 | 1603 | } |
1604 | ||
1605 | template<size_t _Np, typename... _Types> | |
caaaa8fd | 1606 | constexpr const variant_alternative_t<_Np, variant<_Types...>>&& |
85adbce1 | 1607 | get(const variant<_Types...>&& __v) |
1608 | { | |
1609 | static_assert(_Np < sizeof...(_Types), | |
1610 | "The index should be in [0, number of alternatives)"); | |
1611 | if (__v.index() != _Np) | |
1612 | __throw_bad_variant_access("Unexpected index"); | |
caaaa8fd | 1613 | return __detail::__variant::__get<_Np>(std::move(__v)); |
85adbce1 | 1614 | } |
1615 | ||
f03f26fa | 1616 | template<typename _Result_type, typename _Visitor, typename... _Variants> |
2a5d61f9 | 1617 | constexpr decltype(auto) |
49c83dca | 1618 | __do_visit(_Visitor&& __visitor, _Variants&&... __variants) |
85adbce1 | 1619 | { |
2a5d61f9 | 1620 | constexpr auto& __vtable = __detail::__variant::__gen_vtable< |
1621 | _Result_type, _Visitor&&, _Variants&&...>::_S_vtable; | |
1622 | ||
1623 | auto __func_ptr = __vtable._M_access(__variants.index()...); | |
4d1e18aa | 1624 | return (*__func_ptr)(std::forward<_Visitor>(__visitor), |
2a5d61f9 | 1625 | std::forward<_Variants>(__variants)...); |
85adbce1 | 1626 | } |
1627 | ||
49c83dca | 1628 | template<typename _Visitor, typename... _Variants> |
1629 | constexpr decltype(auto) | |
1630 | visit(_Visitor&& __visitor, _Variants&&... __variants) | |
1631 | { | |
1632 | if ((__variants.valueless_by_exception() || ...)) | |
1633 | __throw_bad_variant_access("Unexpected index"); | |
1634 | ||
f03f26fa | 1635 | using _Result_type = std::invoke_result_t<_Visitor, |
1636 | decltype(std::get<0>(std::declval<_Variants>()))...>; | |
1637 | ||
1638 | using _Tag = __detail::__variant::__deduce_visit_result<_Result_type>; | |
1639 | ||
1640 | return __do_visit<_Tag>(std::forward<_Visitor>(__visitor), | |
1641 | std::forward<_Variants>(__variants)...); | |
49c83dca | 1642 | } |
1643 | ||
bfbd20f7 | 1644 | #if __cplusplus > 201703L |
1645 | template<typename _Res, typename _Visitor, typename... _Variants> | |
1646 | constexpr _Res | |
1647 | visit(_Visitor&& __visitor, _Variants&&... __variants) | |
1648 | { | |
1649 | if ((__variants.valueless_by_exception() || ...)) | |
1650 | __throw_bad_variant_access("Unexpected index"); | |
1651 | ||
f03f26fa | 1652 | return __do_visit<_Res>(std::forward<_Visitor>(__visitor), |
1653 | std::forward<_Variants>(__variants)...); | |
bfbd20f7 | 1654 | } |
1655 | #endif | |
1656 | ||
f59d23d2 | 1657 | template<bool, typename... _Types> |
1658 | struct __variant_hash_call_base_impl | |
85adbce1 | 1659 | { |
85adbce1 | 1660 | size_t |
1661 | operator()(const variant<_Types...>& __t) const | |
f9eb8410 | 1662 | noexcept((is_nothrow_invocable_v<hash<decay_t<_Types>>, _Types> && ...)) |
85adbce1 | 1663 | { |
49c83dca | 1664 | size_t __ret; |
f03f26fa | 1665 | __detail::__variant::__raw_visit( |
1666 | [&__t, &__ret](auto&& __t_mem) mutable | |
85adbce1 | 1667 | { |
49c83dca | 1668 | using _Type = __remove_cvref_t<decltype(__t_mem)>; |
1669 | if constexpr (!is_same_v<_Type, | |
1670 | __detail::__variant::__variant_cookie>) | |
1671 | __ret = std::hash<size_t>{}(__t.index()) | |
1672 | + std::hash<_Type>{}(__t_mem); | |
1673 | else | |
1674 | __ret = std::hash<size_t>{}(__t.index()); | |
49c83dca | 1675 | }, __t); |
1676 | return __ret; | |
85adbce1 | 1677 | } |
1678 | }; | |
1679 | ||
f59d23d2 | 1680 | template<typename... _Types> |
1681 | struct __variant_hash_call_base_impl<false, _Types...> {}; | |
1682 | ||
1683 | template<typename... _Types> | |
1684 | using __variant_hash_call_base = | |
1685 | __variant_hash_call_base_impl<(__poison_hash<remove_const_t<_Types>>:: | |
1686 | __enable_hash_call &&...), _Types...>; | |
1687 | ||
1688 | template<typename... _Types> | |
1689 | struct hash<variant<_Types...>> | |
1690 | : private __detail::__variant::_Variant_hash_base< | |
ae6a4ce9 | 1691 | variant<_Types...>, std::index_sequence_for<_Types...>>, |
f59d23d2 | 1692 | public __variant_hash_call_base<_Types...> |
1693 | { | |
b644c5b6 | 1694 | using result_type [[__deprecated__]] = size_t; |
1695 | using argument_type [[__deprecated__]] = variant<_Types...>; | |
f59d23d2 | 1696 | }; |
1697 | ||
85adbce1 | 1698 | template<> |
1699 | struct hash<monostate> | |
1700 | { | |
b644c5b6 | 1701 | using result_type [[__deprecated__]] = size_t; |
1702 | using argument_type [[__deprecated__]] = monostate; | |
85adbce1 | 1703 | |
1704 | size_t | |
1705 | operator()(const monostate& __t) const noexcept | |
1706 | { | |
1707 | constexpr size_t __magic_monostate_hash = -7777; | |
1708 | return __magic_monostate_hash; | |
1709 | } | |
1710 | }; | |
1711 | ||
b644c5b6 | 1712 | template<typename... _Types> |
1713 | struct __is_fast_hash<hash<variant<_Types...>>> | |
1714 | : bool_constant<(__is_fast_hash<_Types>::value && ...)> | |
1715 | { }; | |
1716 | ||
85adbce1 | 1717 | _GLIBCXX_END_NAMESPACE_VERSION |
1718 | } // namespace std | |
1719 | ||
1720 | #endif // C++17 | |
1721 | ||
1722 | #endif // _GLIBCXX_VARIANT |