1// -*- C++ -*- 2//===------------------------------ variant -------------------------------===// 3// 4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5// See https://llvm.org/LICENSE.txt for license information. 6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7// 8//===----------------------------------------------------------------------===// 9 10#ifndef _LIBCPP_VARIANT 11#define _LIBCPP_VARIANT 12 13/* 14 variant synopsis 15 16namespace std { 17 18 // 20.7.2, class template variant 19 template <class... Types> 20 class variant { 21 public: 22 23 // 20.7.2.1, constructors 24 constexpr variant() noexcept(see below); 25 variant(const variant&); // constexpr in C++20 26 variant(variant&&) noexcept(see below); // constexpr in C++20 27 28 template <class T> constexpr variant(T&&) noexcept(see below); 29 30 template <class T, class... Args> 31 constexpr explicit variant(in_place_type_t<T>, Args&&...); 32 33 template <class T, class U, class... Args> 34 constexpr explicit variant( 35 in_place_type_t<T>, initializer_list<U>, Args&&...); 36 37 template <size_t I, class... Args> 38 constexpr explicit variant(in_place_index_t<I>, Args&&...); 39 40 template <size_t I, class U, class... Args> 41 constexpr explicit variant( 42 in_place_index_t<I>, initializer_list<U>, Args&&...); 43 44 // 20.7.2.2, destructor 45 ~variant(); 46 47 // 20.7.2.3, assignment 48 variant& operator=(const variant&); // constexpr in C++20 49 variant& operator=(variant&&) noexcept(see below); // constexpr in C++20 50 51 template <class T> variant& operator=(T&&) noexcept(see below); 52 53 // 20.7.2.4, modifiers 54 template <class T, class... Args> 55 T& emplace(Args&&...); 56 57 template <class T, class U, class... Args> 58 T& emplace(initializer_list<U>, Args&&...); 59 60 template <size_t I, class... Args> 61 variant_alternative_t<I, variant>& emplace(Args&&...); 62 63 template <size_t I, class U, class... Args> 64 variant_alternative_t<I, variant>& emplace(initializer_list<U>, Args&&...); 65 66 // 20.7.2.5, value status 67 constexpr bool valueless_by_exception() const noexcept; 68 constexpr size_t index() const noexcept; 69 70 // 20.7.2.6, swap 71 void swap(variant&) noexcept(see below); 72 }; 73 74 // 20.7.3, variant helper classes 75 template <class T> struct variant_size; // undefined 76 77 template <class T> 78 inline constexpr size_t variant_size_v = variant_size<T>::value; 79 80 template <class T> struct variant_size<const T>; 81 template <class T> struct variant_size<volatile T>; 82 template <class T> struct variant_size<const volatile T>; 83 84 template <class... Types> 85 struct variant_size<variant<Types...>>; 86 87 template <size_t I, class T> struct variant_alternative; // undefined 88 89 template <size_t I, class T> 90 using variant_alternative_t = typename variant_alternative<I, T>::type; 91 92 template <size_t I, class T> struct variant_alternative<I, const T>; 93 template <size_t I, class T> struct variant_alternative<I, volatile T>; 94 template <size_t I, class T> struct variant_alternative<I, const volatile T>; 95 96 template <size_t I, class... Types> 97 struct variant_alternative<I, variant<Types...>>; 98 99 inline constexpr size_t variant_npos = -1; 100 101 // 20.7.4, value access 102 template <class T, class... Types> 103 constexpr bool holds_alternative(const variant<Types...>&) noexcept; 104 105 template <size_t I, class... Types> 106 constexpr variant_alternative_t<I, variant<Types...>>& 107 get(variant<Types...>&); 108 109 template <size_t I, class... Types> 110 constexpr variant_alternative_t<I, variant<Types...>>&& 111 get(variant<Types...>&&); 112 113 template <size_t I, class... Types> 114 constexpr variant_alternative_t<I, variant<Types...>> const& 115 get(const variant<Types...>&); 116 117 template <size_t I, class... Types> 118 constexpr variant_alternative_t<I, variant<Types...>> const&& 119 get(const variant<Types...>&&); 120 121 template <class T, class... Types> 122 constexpr T& get(variant<Types...>&); 123 124 template <class T, class... Types> 125 constexpr T&& get(variant<Types...>&&); 126 127 template <class T, class... Types> 128 constexpr const T& get(const variant<Types...>&); 129 130 template <class T, class... Types> 131 constexpr const T&& get(const variant<Types...>&&); 132 133 template <size_t I, class... Types> 134 constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>> 135 get_if(variant<Types...>*) noexcept; 136 137 template <size_t I, class... Types> 138 constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>> 139 get_if(const variant<Types...>*) noexcept; 140 141 template <class T, class... Types> 142 constexpr add_pointer_t<T> 143 get_if(variant<Types...>*) noexcept; 144 145 template <class T, class... Types> 146 constexpr add_pointer_t<const T> 147 get_if(const variant<Types...>*) noexcept; 148 149 // 20.7.5, relational operators 150 template <class... Types> 151 constexpr bool operator==(const variant<Types...>&, const variant<Types...>&); 152 153 template <class... Types> 154 constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&); 155 156 template <class... Types> 157 constexpr bool operator<(const variant<Types...>&, const variant<Types...>&); 158 159 template <class... Types> 160 constexpr bool operator>(const variant<Types...>&, const variant<Types...>&); 161 162 template <class... Types> 163 constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&); 164 165 template <class... Types> 166 constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&); 167 168 // 20.7.6, visitation 169 template <class Visitor, class... Variants> 170 constexpr see below visit(Visitor&&, Variants&&...); 171 172 // 20.7.7, class monostate 173 struct monostate; 174 175 // 20.7.8, monostate relational operators 176 constexpr bool operator<(monostate, monostate) noexcept; 177 constexpr bool operator>(monostate, monostate) noexcept; 178 constexpr bool operator<=(monostate, monostate) noexcept; 179 constexpr bool operator>=(monostate, monostate) noexcept; 180 constexpr bool operator==(monostate, monostate) noexcept; 181 constexpr bool operator!=(monostate, monostate) noexcept; 182 183 // 20.7.9, specialized algorithms 184 template <class... Types> 185 void swap(variant<Types...>&, variant<Types...>&) noexcept(see below); 186 187 // 20.7.10, class bad_variant_access 188 class bad_variant_access; 189 190 // 20.7.11, hash support 191 template <class T> struct hash; 192 template <class... Types> struct hash<variant<Types...>>; 193 template <> struct hash<monostate>; 194 195} // namespace std 196 197*/ 198 199#include <__config> 200#include <__tuple> 201#include <array> 202#include <exception> 203#include <functional> 204#include <initializer_list> 205#include <new> 206#include <tuple> 207#include <type_traits> 208#include <utility> 209#include <limits> 210#include <version> 211 212#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 213#pragma GCC system_header 214#endif 215 216_LIBCPP_PUSH_MACROS 217#include <__undef_macros> 218 219namespace std { // explicitly not using versioning namespace 220 221class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS bad_variant_access : public exception { 222public: 223 virtual const char* what() const _NOEXCEPT; 224}; 225 226} // namespace std 227 228_LIBCPP_BEGIN_NAMESPACE_STD 229 230// TODO: GCC 5 lies about its support for C++17 (it says it supports it but it 231// really doesn't). That breaks variant, which uses some C++17 features. 232// Remove this once we drop support for GCC 5. 233#if _LIBCPP_STD_VER > 14 && !(defined(_LIBCPP_COMPILER_GCC) && _GNUC_VER_NEW < 6000) 234 235_LIBCPP_NORETURN 236inline _LIBCPP_INLINE_VISIBILITY 237_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 238void __throw_bad_variant_access() { 239#ifndef _LIBCPP_NO_EXCEPTIONS 240 throw bad_variant_access(); 241#else 242 _VSTD::abort(); 243#endif 244} 245 246template <class... _Types> 247class _LIBCPP_TEMPLATE_VIS variant; 248 249template <class _Tp> 250struct _LIBCPP_TEMPLATE_VIS variant_size; 251 252template <class _Tp> 253_LIBCPP_INLINE_VAR constexpr size_t variant_size_v = variant_size<_Tp>::value; 254 255template <class _Tp> 256struct _LIBCPP_TEMPLATE_VIS variant_size<const _Tp> : variant_size<_Tp> {}; 257 258template <class _Tp> 259struct _LIBCPP_TEMPLATE_VIS variant_size<volatile _Tp> : variant_size<_Tp> {}; 260 261template <class _Tp> 262struct _LIBCPP_TEMPLATE_VIS variant_size<const volatile _Tp> 263 : variant_size<_Tp> {}; 264 265template <class... _Types> 266struct _LIBCPP_TEMPLATE_VIS variant_size<variant<_Types...>> 267 : integral_constant<size_t, sizeof...(_Types)> {}; 268 269template <size_t _Ip, class _Tp> 270struct _LIBCPP_TEMPLATE_VIS variant_alternative; 271 272template <size_t _Ip, class _Tp> 273using variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type; 274 275template <size_t _Ip, class _Tp> 276struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const _Tp> 277 : add_const<variant_alternative_t<_Ip, _Tp>> {}; 278 279template <size_t _Ip, class _Tp> 280struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, volatile _Tp> 281 : add_volatile<variant_alternative_t<_Ip, _Tp>> {}; 282 283template <size_t _Ip, class _Tp> 284struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const volatile _Tp> 285 : add_cv<variant_alternative_t<_Ip, _Tp>> {}; 286 287template <size_t _Ip, class... _Types> 288struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, variant<_Types...>> { 289 static_assert(_Ip < sizeof...(_Types), "Index out of bounds in std::variant_alternative<>"); 290 using type = __type_pack_element<_Ip, _Types...>; 291}; 292 293_LIBCPP_INLINE_VAR constexpr size_t variant_npos = static_cast<size_t>(-1); 294 295constexpr int __choose_index_type(unsigned int __num_elem) { 296 if (__num_elem < std::numeric_limits<unsigned char>::max()) 297 return 0; 298 if (__num_elem < std::numeric_limits<unsigned short>::max()) 299 return 1; 300 return 2; 301} 302 303template <size_t _NumAlts> 304using __variant_index_t = 305#ifndef _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION 306 unsigned int; 307#else 308 std::tuple_element_t< 309 __choose_index_type(_NumAlts), 310 std::tuple<unsigned char, unsigned short, unsigned int> 311 >; 312#endif 313 314template <class _IndexType> 315constexpr _IndexType __variant_npos = static_cast<_IndexType>(-1); 316 317namespace __find_detail { 318 319template <class _Tp, class... _Types> 320inline _LIBCPP_INLINE_VISIBILITY 321constexpr size_t __find_index() { 322 constexpr bool __matches[] = {is_same_v<_Tp, _Types>...}; 323 size_t __result = __not_found; 324 for (size_t __i = 0; __i < sizeof...(_Types); ++__i) { 325 if (__matches[__i]) { 326 if (__result != __not_found) { 327 return __ambiguous; 328 } 329 __result = __i; 330 } 331 } 332 return __result; 333} 334 335template <size_t _Index> 336struct __find_unambiguous_index_sfinae_impl 337 : integral_constant<size_t, _Index> {}; 338 339template <> 340struct __find_unambiguous_index_sfinae_impl<__not_found> {}; 341 342template <> 343struct __find_unambiguous_index_sfinae_impl<__ambiguous> {}; 344 345template <class _Tp, class... _Types> 346struct __find_unambiguous_index_sfinae 347 : __find_unambiguous_index_sfinae_impl<__find_index<_Tp, _Types...>()> {}; 348 349} // namespace __find_detail 350 351namespace __variant_detail { 352 353struct __valueless_t {}; 354 355enum class _Trait { _TriviallyAvailable, _Available, _Unavailable }; 356 357template <class _Tp, 358 template <class> class _IsTriviallyAvailable, 359 template <class> class _IsAvailable> 360constexpr _Trait __trait = 361 _IsTriviallyAvailable<_Tp>::value 362 ? _Trait::_TriviallyAvailable 363 : _IsAvailable<_Tp>::value ? _Trait::_Available : _Trait::_Unavailable; 364 365inline _LIBCPP_INLINE_VISIBILITY 366constexpr _Trait __common_trait(initializer_list<_Trait> __traits) { 367 _Trait __result = _Trait::_TriviallyAvailable; 368 for (_Trait __t : __traits) { 369 if (static_cast<int>(__t) > static_cast<int>(__result)) { 370 __result = __t; 371 } 372 } 373 return __result; 374} 375 376template <class... _Types> 377struct __traits { 378 static constexpr _Trait __copy_constructible_trait = 379 __common_trait({__trait<_Types, 380 is_trivially_copy_constructible, 381 is_copy_constructible>...}); 382 383 static constexpr _Trait __move_constructible_trait = 384 __common_trait({__trait<_Types, 385 is_trivially_move_constructible, 386 is_move_constructible>...}); 387 388 static constexpr _Trait __copy_assignable_trait = __common_trait( 389 {__copy_constructible_trait, 390 __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...}); 391 392 static constexpr _Trait __move_assignable_trait = __common_trait( 393 {__move_constructible_trait, 394 __trait<_Types, is_trivially_move_assignable, is_move_assignable>...}); 395 396 static constexpr _Trait __destructible_trait = __common_trait( 397 {__trait<_Types, is_trivially_destructible, is_destructible>...}); 398}; 399 400namespace __access { 401 402struct __union { 403 template <class _Vp> 404 inline _LIBCPP_INLINE_VISIBILITY 405 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) { 406 return _VSTD::forward<_Vp>(__v).__head; 407 } 408 409 template <class _Vp, size_t _Ip> 410 inline _LIBCPP_INLINE_VISIBILITY 411 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) { 412 return __get_alt(_VSTD::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>); 413 } 414}; 415 416struct __base { 417 template <size_t _Ip, class _Vp> 418 inline _LIBCPP_INLINE_VISIBILITY 419 static constexpr auto&& __get_alt(_Vp&& __v) { 420 return __union::__get_alt(_VSTD::forward<_Vp>(__v).__data, 421 in_place_index<_Ip>); 422 } 423}; 424 425struct __variant { 426 template <size_t _Ip, class _Vp> 427 inline _LIBCPP_INLINE_VISIBILITY 428 static constexpr auto&& __get_alt(_Vp&& __v) { 429 return __base::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v).__impl); 430 } 431}; 432 433} // namespace __access 434 435namespace __visitation { 436 437#define _LIBCPP_VARIANT_CASES_4(_Case, _Base) \ 438 _Case(_Base + 0) \ 439 _Case(_Base + 1) \ 440 _Case(_Base + 2) \ 441 _Case(_Base + 3) 442 443#define _LIBCPP_VARIANT_CASES_16(_Case, _Base) \ 444 _LIBCPP_VARIANT_CASES_4(_Case, _Base + 4 * 0) \ 445 _LIBCPP_VARIANT_CASES_4(_Case, _Base + 4 * 1) \ 446 _LIBCPP_VARIANT_CASES_4(_Case, _Base + 4 * 2) \ 447 _LIBCPP_VARIANT_CASES_4(_Case, _Base + 4 * 3) 448 449#define _LIBCPP_VARIANT_CASES_64(_Case, _Base) \ 450 _LIBCPP_VARIANT_CASES_16(_Case, _Base + 16 * 0) \ 451 _LIBCPP_VARIANT_CASES_16(_Case, _Base + 16 * 1) \ 452 _LIBCPP_VARIANT_CASES_16(_Case, _Base + 16 * 2) \ 453 _LIBCPP_VARIANT_CASES_16(_Case, _Base + 16 * 3) 454 455#define _LIBCPP_VARIANT_CASES_256(_Case, _Base) \ 456 _LIBCPP_VARIANT_CASES_64(_Case, _Base + 64 * 0) \ 457 _LIBCPP_VARIANT_CASES_64(_Case, _Base + 64 * 1) \ 458 _LIBCPP_VARIANT_CASES_64(_Case, _Base + 64 * 2) \ 459 _LIBCPP_VARIANT_CASES_64(_Case, _Base + 64 * 3) 460 461#define _LIBCPP_VARIANT_CASES(_NumCases, _Case) \ 462 _LIBCPP_CONCAT(_LIBCPP_VARIANT_CASES_, _NumCases)(_Case, 0) 463 464#define _LIBCPP_VARIANT_SWITCH_MAX 256 465 466template <class _Iter, class _Fp, size_t... _Is> 467inline _LIBCPP_INLINE_VISIBILITY 468static constexpr void __fill_cartesian_impl( 469 _Iter __iter, _Fp __f, index_sequence<_Is...>) { 470 *__iter = __f(integral_constant<size_t, _Is>{}...); 471} 472 473template <class _Iter, class _Fp, size_t... _Is, size_t... _Js, class... _Ls> 474inline _LIBCPP_INLINE_VISIBILITY 475static constexpr void __fill_cartesian_impl( 476 _Iter __iter, _Fp __f, index_sequence<_Is...>, index_sequence<_Js...>, _Ls... __ls) { 477 constexpr size_t _Mp = (1 * ... * _Ls::size()); 478 (__fill_cartesian_impl( 479 __iter + _Js * _Mp, __f, index_sequence<_Is..., _Js>{}, __ls...), ...); 480} 481 482template <size_t... _Ns, class _Iter, class _Fp> 483inline _LIBCPP_INLINE_VISIBILITY 484static constexpr void __fill_cartesian(_Iter __iter, _Fp __f) { 485 __fill_cartesian_impl( 486 __iter, __f, index_sequence<>{}, make_index_sequence<_Ns>{}...); 487} 488 489template <size_t _Np, size_t... _Ns> 490struct __multi { 491 inline _LIBCPP_INLINE_VISIBILITY 492 static constexpr size_t __size = (_Np * ... * _Ns); 493 494 inline _LIBCPP_INLINE_VISIBILITY 495 static constexpr size_t 496 __index(const size_t (&__is)[sizeof...(_Ns) + 1]) noexcept { 497 constexpr size_t __ns[] = {_Ns..., 1}; 498 size_t __result = 0; 499 for (size_t __i = 0; __i < sizeof...(_Ns) + 1; ++__i) { 500 if (__is[__i] == variant_npos) { 501 return variant_npos; 502 } 503 __result += __is[__i]; 504 __result *= __ns[__i]; 505 } 506 return __result; 507 } 508}; 509 510template <size_t... _Ns> 511struct __indices { 512 inline _LIBCPP_INLINE_VISIBILITY 513 static constexpr auto __value = [] { 514 using _Tp = array<size_t, sizeof...(_Ns)>; 515 array<_Tp, (1 * ... * _Ns)> __result = {}; 516 __fill_cartesian<_Ns...>(__result.begin(), 517 [](auto... __is) -> _Tp { return {__is...}; }); 518 return __result; 519 }(); 520}; 521 522template <size_t... _Ns, class _Fp, class _Rp, class... _Args> 523inline _LIBCPP_INLINE_VISIBILITY 524static constexpr auto __make_vtable_impl(_Fp __f, _Rp (*)(_Args...)) { 525 array<_Rp (*)(_Args...), (1 * ... * _Ns) + 1> __result = { 526 [](_Args...) -> _Rp { __throw_bad_variant_access(); } 527 }; 528 __fill_cartesian<_Ns...>(__result.begin() + 1, __f); 529 return __result; 530} 531 532template <size_t... _Ns, class _Fp> 533inline _LIBCPP_INLINE_VISIBILITY 534static constexpr auto __make_vtable(_Fp __f) { 535 using _Tp = decltype(__f(integral_constant<size_t, (_Ns, 0)>{}...)); 536 return __make_vtable_impl<_Ns...>(__f, _Tp{}); 537} 538 539struct __base { 540 template <class _Vis, class... _Vs> 541 struct __dispatch { 542 template <size_t... _Is> 543 inline _LIBCPP_INLINE_VISIBILITY 544 constexpr auto operator()(integral_constant<size_t, _Is>...) const noexcept { 545 return +[](_Vis&& __vis, _Vs&&... __vs) -> decltype(auto) { 546 return __invoke_constexpr( 547 _VSTD::forward<_Vis>(__vis), 548 __access::__base::__get_alt<_Is>(_VSTD::forward<_Vs>(__vs))...); 549 }; 550 } 551 }; 552 553 template <class _Vis, class _Vp, class _Wp> 554 inline _LIBCPP_INLINE_VISIBILITY 555 static constexpr decltype(auto) 556 __visit_alt_at(size_t __index, _Vis&& __vis, _Vp&& __v, _Wp&& __w) { 557 constexpr size_t __size = __uncvref_t<_Vp>::__size(); 558 static_assert(__size == __uncvref_t<_Wp>::__size()); 559 constexpr auto __dispatch_at = [](auto __i) { 560 return __dispatch<_Vis, _Vp, _Wp>{}(__i, __i); 561 }; 562#define _LIBCPP_VARIANT_CASE(_Ip) \ 563 case _Ip: { \ 564 if constexpr (_Ip < __size) { \ 565 return __dispatch_at(integral_constant<size_t, _Ip>{})( \ 566 _VSTD::forward<_Vis>(__vis), \ 567 _VSTD::forward<_Vp>(__v), \ 568 _VSTD::forward<_Wp>(__w)); \ 569 } else { \ 570 _LIBCPP_UNREACHABLE(); \ 571 } \ 572 } 573 if constexpr (__size <= _LIBCPP_VARIANT_SWITCH_MAX) { 574 switch (__index) { 575 _LIBCPP_VARIANT_CASES(_LIBCPP_VARIANT_SWITCH_MAX, _LIBCPP_VARIANT_CASE) 576 default: __throw_bad_variant_access(); 577 } 578 } else { 579 constexpr auto __vtable = __make_vtable<__size>(__dispatch_at); 580 return __vtable[__index + 1](_VSTD::forward<_Vis>(__vis), 581 _VSTD::forward<_Vp>(__v), 582 _VSTD::forward<_Wp>(__w)); 583 } 584#undef _LIBCPP_VARIANT_CASE 585 } 586 587 template <size_t... _Is, class _Vis, class... _Vs> 588 inline _LIBCPP_INLINE_VISIBILITY 589 static constexpr decltype(auto) __visit_alt(_Vis&& __vis, _Vs&&... __vs) { 590 if constexpr (sizeof...(_Vs) == 0) { 591 return __invoke_constexpr(_VSTD::forward<_Vis>(__vis)); 592 } else { 593 return __visit_alt_impl(index_sequence_for<_Vs...>{}, 594 _VSTD::forward<_Vis>(__vis), 595 _VSTD::forward<_Vs>(__vs)...); 596 } 597 } 598 599 template <size_t... _Is, class _Vis, class... _Vs> 600 inline _LIBCPP_INLINE_VISIBILITY 601 static constexpr decltype(auto) 602 __visit_alt_impl(index_sequence<_Is...>, _Vis&& __vis, _Vs&&... __vs) { 603 using __multi = __multi<__uncvref_t<_Vs>::__size()...>; 604 constexpr __dispatch<_Vis, _Vs...> __dispatch; 605#define _LIBCPP_VARIANT_CASE(_Ip) \ 606 case _Ip: { \ 607 if constexpr (_Ip < __multi::__size) { \ 608 return __dispatch(integral_constant<size_t, __itable[_Ip][_Is]>{}...)( \ 609 _VSTD::forward<_Vis>(__vis), _VSTD::forward<_Vs>(__vs)...); \ 610 } else { \ 611 _LIBCPP_UNREACHABLE(); \ 612 } \ 613 } 614 if constexpr (__multi::__size <= _LIBCPP_VARIANT_SWITCH_MAX) { 615 constexpr const auto& __itable = 616 __indices<__uncvref_t<_Vs>::__size()...>::__value; 617 switch (__multi::__index({__vs.index()...})) { 618 _LIBCPP_VARIANT_CASES(_LIBCPP_VARIANT_SWITCH_MAX, _LIBCPP_VARIANT_CASE) 619 default: __throw_bad_variant_access(); 620 } 621 } else { 622 constexpr auto __vtable = 623 __make_vtable<__uncvref_t<_Vs>::__size()...>(__dispatch); 624 return __vtable[__multi::__index({__vs.index()...}) + 1]( 625 _VSTD::forward<_Vis>(__vis), _VSTD::forward<_Vs>(__vs)...); 626 } 627#undef _LIBCPP_VARIANT_CASE 628 } 629}; 630 631struct __variant { 632 template <class _Vis, class _Vp, class _Wp> 633 inline _LIBCPP_INLINE_VISIBILITY 634 static constexpr decltype(auto) 635 __visit_alt_at(size_t __index, _Vis&& __vis, _Vp&& __v, _Wp&& __w) { 636 return __base::__visit_alt_at(__index, 637 _VSTD::forward<_Vis>(__vis), 638 _VSTD::forward<_Vp>(__v).__impl, 639 _VSTD::forward<_Wp>(__w).__impl); 640 } 641 642 template <class _Vis, class... _Vs> 643 inline _LIBCPP_INLINE_VISIBILITY 644 static constexpr decltype(auto) __visit_alt(_Vis&& __vis, _Vs&&... __vs) { 645 return __base::__visit_alt(_VSTD::forward<_Vis>(__vis), 646 _VSTD::forward<_Vs>(__vs).__impl...); 647 } 648 649 template <class _Vis, class _Vp, class _Wp> 650 inline _LIBCPP_INLINE_VISIBILITY 651 static constexpr decltype(auto) 652 __visit_value_at(size_t __index, _Vis&& __vis, _Vp&& __v, _Wp&& __w) { 653 return __visit_alt_at(__index, 654 __make_value_visitor(_VSTD::forward<_Vis>(__vis)), 655 _VSTD::forward<_Vp>(__v), 656 _VSTD::forward<_Wp>(__w)); 657 } 658 659 template <class _Vis, class... _Vs> 660 inline _LIBCPP_INLINE_VISIBILITY 661 static constexpr decltype(auto) __visit_value(_Vis&& __vis, _Vs&&... __vs) { 662 return __visit_alt(__make_value_visitor(_VSTD::forward<_Vis>(__vis)), 663 _VSTD::forward<_Vs>(__vs)...); 664 } 665 666private: 667 template <class _Vis, class... _Values> 668 inline _LIBCPP_INLINE_VISIBILITY 669 static constexpr void __std_visit_exhaustive_visitor_check() { 670 static_assert(is_invocable_v<_Vis, _Values...>, 671 "`std::visit` requires the visitor to be exhaustive."); 672 } 673 674 template <class _Vis> 675 struct __value_visitor { 676 template <class... _Alts> 677 inline _LIBCPP_INLINE_VISIBILITY 678 constexpr decltype(auto) operator()(_Alts&&... __alts) const { 679 __std_visit_exhaustive_visitor_check< 680 _Vis, decltype((_VSTD::forward<_Alts>(__alts).__value))...>(); 681 return __invoke_constexpr(_VSTD::forward<_Vis>(__vis), 682 _VSTD::forward<_Alts>(__alts).__value...); 683 } 684 _Vis&& __vis; 685 }; 686 687 template <class _Vis> 688 inline _LIBCPP_INLINE_VISIBILITY 689 static constexpr auto __make_value_visitor(_Vis&& __vis) { 690 return __value_visitor<_Vis>{_VSTD::forward<_Vis>(__vis)}; 691 } 692}; 693 694#undef _LIBCPP_VARIANT_SWITCH_MAX 695#undef _LIBCPP_VARIANT_CASES 696#undef _LIBCPP_VARIANT_CASES_256 697#undef _LIBCPP_VARIANT_CASES_64 698#undef _LIBCPP_VARIANT_CASES_16 699#undef _LIBCPP_VARIANT_CASES_4 700 701} // namespace __visitation 702 703template <size_t _Index, class _Tp> 704struct _LIBCPP_TEMPLATE_VIS __alt { 705 using __value_type = _Tp; 706 707 template <class... _Args> 708 inline _LIBCPP_INLINE_VISIBILITY 709 explicit constexpr __alt(in_place_t, _Args&&... __args) 710 : __value(_VSTD::forward<_Args>(__args)...) {} 711 712 __value_type __value; 713}; 714 715template <_Trait _DestructibleTrait, size_t _Index, class... _Types> 716union _LIBCPP_TEMPLATE_VIS __union; 717 718template <_Trait _DestructibleTrait, size_t _Index> 719union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {}; 720 721#define _LIBCPP_VARIANT_UNION(destructible_trait, destructor) \ 722 template <size_t _Index, class _Tp, class... _Types> \ 723 union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \ 724 _Index, \ 725 _Tp, \ 726 _Types...> { \ 727 public: \ 728 inline _LIBCPP_INLINE_VISIBILITY \ 729 explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \ 730 \ 731 template <class... _Args> \ 732 inline _LIBCPP_INLINE_VISIBILITY \ 733 explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \ 734 : __head(in_place, _VSTD::forward<_Args>(__args)...) {} \ 735 \ 736 template <size_t _Ip, class... _Args> \ 737 inline _LIBCPP_INLINE_VISIBILITY \ 738 explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \ 739 : __tail(in_place_index<_Ip - 1>, _VSTD::forward<_Args>(__args)...) {} \ 740 \ 741 __union(const __union&) = default; \ 742 __union(__union&&) = default; \ 743 \ 744 destructor \ 745 \ 746 __union& operator=(const __union&) = default; \ 747 __union& operator=(__union&&) = default; \ 748 \ 749 private: \ 750 char __dummy; \ 751 __alt<_Index, _Tp> __head; \ 752 __union<destructible_trait, _Index + 1, _Types...> __tail; \ 753 \ 754 friend struct __access::__union; \ 755 } 756 757_LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;); 758_LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {}); 759_LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;); 760 761#undef _LIBCPP_VARIANT_UNION 762 763template <_Trait _DestructibleTrait, class... _Types> 764class _LIBCPP_TEMPLATE_VIS __base { 765public: 766 using __index_t = __variant_index_t<sizeof...(_Types)>; 767 768 inline _LIBCPP_INLINE_VISIBILITY 769 explicit constexpr __base(__valueless_t tag) noexcept 770 : __data(tag), __index(__variant_npos<__index_t>) {} 771 772 template <size_t _Ip, class... _Args> 773 inline _LIBCPP_INLINE_VISIBILITY 774 explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args) 775 : 776 __data(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...), 777 __index(_Ip) {} 778 779 inline _LIBCPP_INLINE_VISIBILITY 780 constexpr bool valueless_by_exception() const noexcept { 781 return index() == variant_npos; 782 } 783 784 inline _LIBCPP_INLINE_VISIBILITY 785 constexpr size_t index() const noexcept { 786 return __index == __variant_npos<__index_t> ? variant_npos : __index; 787 } 788 789protected: 790 inline _LIBCPP_INLINE_VISIBILITY 791 constexpr auto&& __as_base() & { return *this; } 792 793 inline _LIBCPP_INLINE_VISIBILITY 794 constexpr auto&& __as_base() && { return _VSTD::move(*this); } 795 796 inline _LIBCPP_INLINE_VISIBILITY 797 constexpr auto&& __as_base() const & { return *this; } 798 799 inline _LIBCPP_INLINE_VISIBILITY 800 constexpr auto&& __as_base() const && { return _VSTD::move(*this); } 801 802 inline _LIBCPP_INLINE_VISIBILITY 803 static constexpr size_t __size() { return sizeof...(_Types); } 804 805 __union<_DestructibleTrait, 0, _Types...> __data; 806 __index_t __index; 807 808 friend struct __access::__base; 809 friend struct __visitation::__base; 810}; 811 812template <class _Traits, _Trait = _Traits::__destructible_trait> 813class _LIBCPP_TEMPLATE_VIS __dtor; 814 815#define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy) \ 816 template <class... _Types> \ 817 class _LIBCPP_TEMPLATE_VIS __dtor<__traits<_Types...>, \ 818 destructible_trait> \ 819 : public __base<destructible_trait, _Types...> { \ 820 using __base_type = __base<destructible_trait, _Types...>; \ 821 using __index_t = typename __base_type::__index_t; \ 822 \ 823 public: \ 824 using __base_type::__base_type; \ 825 using __base_type::operator=; \ 826 \ 827 __dtor(const __dtor&) = default; \ 828 __dtor(__dtor&&) = default; \ 829 destructor \ 830 __dtor& operator=(const __dtor&) = default; \ 831 __dtor& operator=(__dtor&&) = default; \ 832 \ 833 protected: \ 834 inline _LIBCPP_INLINE_VISIBILITY \ 835 destroy \ 836 } 837 838_LIBCPP_VARIANT_DESTRUCTOR( 839 _Trait::_TriviallyAvailable, 840 ~__dtor() = default;, 841 void __destroy() noexcept { this->__index = __variant_npos<__index_t>; }); 842 843_LIBCPP_VARIANT_DESTRUCTOR( 844 _Trait::_Available, 845 ~__dtor() { __destroy(); }, 846 void __destroy() noexcept { 847 if (!this->valueless_by_exception()) { 848 __visitation::__base::__visit_alt( 849 [](auto& __alt) noexcept { 850 using __alt_type = __uncvref_t<decltype(__alt)>; 851 __alt.~__alt_type(); 852 }, 853 *this); 854 } 855 this->__index = __variant_npos<__index_t>; 856 }); 857 858_LIBCPP_VARIANT_DESTRUCTOR( 859 _Trait::_Unavailable, 860 ~__dtor() = delete;, 861 void __destroy() noexcept = delete;); 862 863#undef _LIBCPP_VARIANT_DESTRUCTOR 864 865template <class _Traits> 866class _LIBCPP_TEMPLATE_VIS __ctor : public __dtor<_Traits> { 867 using __base_type = __dtor<_Traits>; 868 869public: 870 using __base_type::__base_type; 871 using __base_type::operator=; 872 873protected: 874 template <size_t _Ip, class _Tp, class... _Args> 875 inline _LIBCPP_INLINE_VISIBILITY 876 static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) { 877 auto* __result = ::new ((void*)_VSTD::addressof(__a)) 878 __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...); 879 return __result->__value; 880 } 881 882 template <class _Rhs> 883 inline _LIBCPP_INLINE_VISIBILITY 884 static void __generic_construct(__ctor& __lhs, _Rhs&& __rhs) { 885 __lhs.__destroy(); 886 if (!__rhs.valueless_by_exception()) { 887 __visitation::__base::__visit_alt_at( 888 __rhs.index(), 889 [](auto& __lhs_alt, auto&& __rhs_alt) { 890 __construct_alt( 891 __lhs_alt, 892 _VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value); 893 }, 894 __lhs, _VSTD::forward<_Rhs>(__rhs)); 895 __lhs.__index = __rhs.index(); 896 } 897 } 898}; 899 900template <class _Traits, _Trait = _Traits::__move_constructible_trait> 901class _LIBCPP_TEMPLATE_VIS __move_constructor; 902 903#define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, \ 904 move_constructor) \ 905 template <class... _Types> \ 906 class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>, \ 907 move_constructible_trait> \ 908 : public __ctor<__traits<_Types...>> { \ 909 using __base_type = __ctor<__traits<_Types...>>; \ 910 \ 911 public: \ 912 using __base_type::__base_type; \ 913 using __base_type::operator=; \ 914 \ 915 __move_constructor(const __move_constructor&) = default; \ 916 move_constructor \ 917 ~__move_constructor() = default; \ 918 __move_constructor& operator=(const __move_constructor&) = default; \ 919 __move_constructor& operator=(__move_constructor&&) = default; \ 920 } 921 922_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 923 _Trait::_TriviallyAvailable, 924 __move_constructor(__move_constructor&& __that) = default;); 925 926_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 927 _Trait::_Available, 928 __move_constructor(__move_constructor&& __that) noexcept( 929 __all<is_nothrow_move_constructible_v<_Types>...>::value) 930 : __move_constructor(__valueless_t{}) { 931 this->__generic_construct(*this, _VSTD::move(__that)); 932 }); 933 934_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 935 _Trait::_Unavailable, 936 __move_constructor(__move_constructor&&) = delete;); 937 938#undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR 939 940template <class _Traits, _Trait = _Traits::__copy_constructible_trait> 941class _LIBCPP_TEMPLATE_VIS __copy_constructor; 942 943#define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, \ 944 copy_constructor) \ 945 template <class... _Types> \ 946 class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \ 947 copy_constructible_trait> \ 948 : public __move_constructor<__traits<_Types...>> { \ 949 using __base_type = __move_constructor<__traits<_Types...>>; \ 950 \ 951 public: \ 952 using __base_type::__base_type; \ 953 using __base_type::operator=; \ 954 \ 955 copy_constructor \ 956 __copy_constructor(__copy_constructor&&) = default; \ 957 ~__copy_constructor() = default; \ 958 __copy_constructor& operator=(const __copy_constructor&) = default; \ 959 __copy_constructor& operator=(__copy_constructor&&) = default; \ 960 } 961 962_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 963 _Trait::_TriviallyAvailable, 964 __copy_constructor(const __copy_constructor& __that) = default;); 965 966_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 967 _Trait::_Available, 968 __copy_constructor(const __copy_constructor& __that) 969 : __copy_constructor(__valueless_t{}) { 970 this->__generic_construct(*this, __that); 971 }); 972 973_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 974 _Trait::_Unavailable, 975 __copy_constructor(const __copy_constructor&) = delete;); 976 977#undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR 978 979template <class _Traits> 980class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> { 981 using __base_type = __copy_constructor<_Traits>; 982 983public: 984 using __base_type::__base_type; 985 using __base_type::operator=; 986 987 template <size_t _Ip, class... _Args> 988 inline _LIBCPP_INLINE_VISIBILITY 989 auto& __emplace(_Args&&... __args) { 990 this->__destroy(); 991 auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this), 992 _VSTD::forward<_Args>(__args)...); 993 this->__index = _Ip; 994 return __res; 995 } 996 997protected: 998 template <size_t _Ip, class _Tp, class _Arg> 999 inline _LIBCPP_INLINE_VISIBILITY 1000 void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) { 1001 if (this->index() == _Ip) { 1002 __a.__value = _VSTD::forward<_Arg>(__arg); 1003 } else { 1004 struct { 1005 void operator()(true_type) const { 1006 __this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg)); 1007 } 1008 void operator()(false_type) const { 1009 __this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg))); 1010 } 1011 __assignment* __this; 1012 _Arg&& __arg; 1013 } __impl{this, _VSTD::forward<_Arg>(__arg)}; 1014 __impl(bool_constant<is_nothrow_constructible_v<_Tp, _Arg> || 1015 !is_nothrow_move_constructible_v<_Tp>>{}); 1016 } 1017 } 1018 1019 template <class _That> 1020 inline _LIBCPP_INLINE_VISIBILITY 1021 void __generic_assign(_That&& __that) { 1022 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 1023 // do nothing. 1024 } else if (__that.valueless_by_exception()) { 1025 this->__destroy(); 1026 } else { 1027 __visitation::__base::__visit_alt_at( 1028 __that.index(), 1029 [this](auto& __this_alt, auto&& __that_alt) { 1030 this->__assign_alt( 1031 __this_alt, 1032 _VSTD::forward<decltype(__that_alt)>(__that_alt).__value); 1033 }, 1034 *this, _VSTD::forward<_That>(__that)); 1035 } 1036 } 1037}; 1038 1039template <class _Traits, _Trait = _Traits::__move_assignable_trait> 1040class _LIBCPP_TEMPLATE_VIS __move_assignment; 1041 1042#define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, \ 1043 move_assignment) \ 1044 template <class... _Types> \ 1045 class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \ 1046 move_assignable_trait> \ 1047 : public __assignment<__traits<_Types...>> { \ 1048 using __base_type = __assignment<__traits<_Types...>>; \ 1049 \ 1050 public: \ 1051 using __base_type::__base_type; \ 1052 using __base_type::operator=; \ 1053 \ 1054 __move_assignment(const __move_assignment&) = default; \ 1055 __move_assignment(__move_assignment&&) = default; \ 1056 ~__move_assignment() = default; \ 1057 __move_assignment& operator=(const __move_assignment&) = default; \ 1058 move_assignment \ 1059 } 1060 1061_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 1062 _Trait::_TriviallyAvailable, 1063 __move_assignment& operator=(__move_assignment&& __that) = default;); 1064 1065_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 1066 _Trait::_Available, 1067 __move_assignment& operator=(__move_assignment&& __that) noexcept( 1068 __all<(is_nothrow_move_constructible_v<_Types> && 1069 is_nothrow_move_assignable_v<_Types>)...>::value) { 1070 this->__generic_assign(_VSTD::move(__that)); 1071 return *this; 1072 }); 1073 1074_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 1075 _Trait::_Unavailable, 1076 __move_assignment& operator=(__move_assignment&&) = delete;); 1077 1078#undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT 1079 1080template <class _Traits, _Trait = _Traits::__copy_assignable_trait> 1081class _LIBCPP_TEMPLATE_VIS __copy_assignment; 1082 1083#define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, \ 1084 copy_assignment) \ 1085 template <class... _Types> \ 1086 class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \ 1087 copy_assignable_trait> \ 1088 : public __move_assignment<__traits<_Types...>> { \ 1089 using __base_type = __move_assignment<__traits<_Types...>>; \ 1090 \ 1091 public: \ 1092 using __base_type::__base_type; \ 1093 using __base_type::operator=; \ 1094 \ 1095 __copy_assignment(const __copy_assignment&) = default; \ 1096 __copy_assignment(__copy_assignment&&) = default; \ 1097 ~__copy_assignment() = default; \ 1098 copy_assignment \ 1099 __copy_assignment& operator=(__copy_assignment&&) = default; \ 1100 } 1101 1102_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1103 _Trait::_TriviallyAvailable, 1104 __copy_assignment& operator=(const __copy_assignment& __that) = default;); 1105 1106_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1107 _Trait::_Available, 1108 __copy_assignment& operator=(const __copy_assignment& __that) { 1109 this->__generic_assign(__that); 1110 return *this; 1111 }); 1112 1113_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1114 _Trait::_Unavailable, 1115 __copy_assignment& operator=(const __copy_assignment&) = delete;); 1116 1117#undef _LIBCPP_VARIANT_COPY_ASSIGNMENT 1118 1119template <class... _Types> 1120class _LIBCPP_TEMPLATE_VIS __impl 1121 : public __copy_assignment<__traits<_Types...>> { 1122 using __base_type = __copy_assignment<__traits<_Types...>>; 1123 1124public: 1125 using __base_type::__base_type; 1126 using __base_type::operator=; 1127 1128 template <size_t _Ip, class _Arg> 1129 inline _LIBCPP_INLINE_VISIBILITY 1130 void __assign(_Arg&& __arg) { 1131 this->__assign_alt(__access::__base::__get_alt<_Ip>(*this), 1132 _VSTD::forward<_Arg>(__arg)); 1133 } 1134 1135 inline _LIBCPP_INLINE_VISIBILITY 1136 void __swap(__impl& __that) { 1137 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 1138 // do nothing. 1139 } else if (this->index() == __that.index()) { 1140 __visitation::__base::__visit_alt_at( 1141 this->index(), 1142 [](auto& __this_alt, auto& __that_alt) { 1143 using _VSTD::swap; 1144 swap(__this_alt.__value, __that_alt.__value); 1145 }, 1146 *this, 1147 __that); 1148 } else { 1149 __impl* __lhs = this; 1150 __impl* __rhs = _VSTD::addressof(__that); 1151 if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) { 1152 _VSTD::swap(__lhs, __rhs); 1153 } 1154 __impl __tmp(_VSTD::move(*__rhs)); 1155#ifndef _LIBCPP_NO_EXCEPTIONS 1156 if constexpr (__all<is_nothrow_move_constructible_v<_Types>...>::value) { 1157 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1158 } else { 1159 // EXTENSION: When the move construction of `__lhs` into `__rhs` throws 1160 // and `__tmp` is nothrow move constructible then we move `__tmp` back 1161 // into `__rhs` and provide the strong exception safety guarantee. 1162 try { 1163 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1164 } catch (...) { 1165 if (__tmp.__move_nothrow()) { 1166 this->__generic_construct(*__rhs, _VSTD::move(__tmp)); 1167 } 1168 throw; 1169 } 1170 } 1171#else 1172 // this isn't consolidated with the `if constexpr` branch above due to 1173 // `throw` being ill-formed with exceptions disabled even when discarded. 1174 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1175#endif 1176 this->__generic_construct(*__lhs, _VSTD::move(__tmp)); 1177 } 1178 } 1179 1180private: 1181 inline _LIBCPP_INLINE_VISIBILITY 1182 bool __move_nothrow() const { 1183 constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...}; 1184 return this->valueless_by_exception() || __results[this->index()]; 1185 } 1186}; 1187 1188struct __no_narrowing_check { 1189 template <class _Dest, class _Source> 1190 using _Apply = __identity<_Dest>; 1191}; 1192 1193struct __narrowing_check { 1194 template <class _Dest> 1195 static auto __test_impl(_Dest (&&)[1]) -> __identity<_Dest>; 1196 template <class _Dest, class _Source> 1197 using _Apply _LIBCPP_NODEBUG_TYPE = decltype(__test_impl<_Dest>({std::declval<_Source>()})); 1198}; 1199 1200template <class _Dest, class _Source> 1201using __check_for_narrowing _LIBCPP_NODEBUG_TYPE = 1202 typename _If< 1203#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT 1204 false && 1205#endif 1206 is_arithmetic<_Dest>::value, 1207 __narrowing_check, 1208 __no_narrowing_check 1209 >::template _Apply<_Dest, _Source>; 1210 1211template <class _Tp, size_t _Idx> 1212struct __overload { 1213 template <class _Up> 1214 auto operator()(_Tp, _Up&&) const -> __check_for_narrowing<_Tp, _Up>; 1215}; 1216 1217template <class _Tp, size_t> 1218struct __overload_bool { 1219 template <class _Up, class _Ap = __uncvref_t<_Up>> 1220 auto operator()(bool, _Up&&) const 1221 -> enable_if_t<is_same_v<_Ap, bool>, __identity<_Tp>>; 1222}; 1223 1224template <size_t _Idx> 1225struct __overload<bool, _Idx> : __overload_bool<bool, _Idx> {}; 1226template <size_t _Idx> 1227struct __overload<bool const, _Idx> : __overload_bool<bool const, _Idx> {}; 1228template <size_t _Idx> 1229struct __overload<bool volatile, _Idx> : __overload_bool<bool volatile, _Idx> {}; 1230template <size_t _Idx> 1231struct __overload<bool const volatile, _Idx> : __overload_bool<bool const volatile, _Idx> {}; 1232 1233template <class ..._Bases> 1234struct __all_overloads : _Bases... { 1235 void operator()() const; 1236 using _Bases::operator()...; 1237}; 1238 1239template <class IdxSeq> 1240struct __make_overloads_imp; 1241 1242template <size_t ..._Idx> 1243struct __make_overloads_imp<__tuple_indices<_Idx...> > { 1244 template <class ..._Types> 1245 using _Apply _LIBCPP_NODEBUG_TYPE = __all_overloads<__overload<_Types, _Idx>...>; 1246}; 1247 1248template <class ..._Types> 1249using _MakeOverloads _LIBCPP_NODEBUG_TYPE = typename __make_overloads_imp< 1250 __make_indices_imp<sizeof...(_Types), 0> >::template _Apply<_Types...>; 1251 1252template <class _Tp, class... _Types> 1253using __best_match_t = 1254 typename invoke_result_t<_MakeOverloads<_Types...>, _Tp, _Tp>::type; 1255 1256} // __variant_detail 1257 1258template <class... _Types> 1259class _LIBCPP_TEMPLATE_VIS variant 1260 : private __sfinae_ctor_base< 1261 __all<is_copy_constructible_v<_Types>...>::value, 1262 __all<is_move_constructible_v<_Types>...>::value>, 1263 private __sfinae_assign_base< 1264 __all<(is_copy_constructible_v<_Types> && 1265 is_copy_assignable_v<_Types>)...>::value, 1266 __all<(is_move_constructible_v<_Types> && 1267 is_move_assignable_v<_Types>)...>::value> { 1268 static_assert(0 < sizeof...(_Types), 1269 "variant must consist of at least one alternative."); 1270 1271 static_assert(__all<!is_array_v<_Types>...>::value, 1272 "variant can not have an array type as an alternative."); 1273 1274 static_assert(__all<!is_reference_v<_Types>...>::value, 1275 "variant can not have a reference type as an alternative."); 1276 1277 static_assert(__all<!is_void_v<_Types>...>::value, 1278 "variant can not have a void type as an alternative."); 1279 1280 using __first_type = variant_alternative_t<0, variant>; 1281 1282public: 1283 template <bool _Dummy = true, 1284 enable_if_t<__dependent_type<is_default_constructible<__first_type>, 1285 _Dummy>::value, 1286 int> = 0> 1287 inline _LIBCPP_INLINE_VISIBILITY 1288 constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>) 1289 : __impl(in_place_index<0>) {} 1290 1291 variant(const variant&) = default; 1292 variant(variant&&) = default; 1293 1294 template < 1295 class _Arg, 1296 enable_if_t<!is_same_v<__uncvref_t<_Arg>, variant>, int> = 0, 1297 enable_if_t<!__is_inplace_type<__uncvref_t<_Arg>>::value, int> = 0, 1298 enable_if_t<!__is_inplace_index<__uncvref_t<_Arg>>::value, int> = 0, 1299 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1300 size_t _Ip = 1301 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1302 enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0> 1303 inline _LIBCPP_INLINE_VISIBILITY 1304 constexpr variant(_Arg&& __arg) noexcept( 1305 is_nothrow_constructible_v<_Tp, _Arg>) 1306 : __impl(in_place_index<_Ip>, _VSTD::forward<_Arg>(__arg)) {} 1307 1308 template <size_t _Ip, class... _Args, 1309 class = enable_if_t<(_Ip < sizeof...(_Types)), int>, 1310 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1311 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1312 inline _LIBCPP_INLINE_VISIBILITY 1313 explicit constexpr variant( 1314 in_place_index_t<_Ip>, 1315 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>) 1316 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {} 1317 1318 template < 1319 size_t _Ip, 1320 class _Up, 1321 class... _Args, 1322 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1323 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1324 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1325 int> = 0> 1326 inline _LIBCPP_INLINE_VISIBILITY 1327 explicit constexpr variant( 1328 in_place_index_t<_Ip>, 1329 initializer_list<_Up> __il, 1330 _Args&&... __args) noexcept( 1331 is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) 1332 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {} 1333 1334 template < 1335 class _Tp, 1336 class... _Args, 1337 size_t _Ip = 1338 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1339 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1340 inline _LIBCPP_INLINE_VISIBILITY 1341 explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept( 1342 is_nothrow_constructible_v<_Tp, _Args...>) 1343 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {} 1344 1345 template < 1346 class _Tp, 1347 class _Up, 1348 class... _Args, 1349 size_t _Ip = 1350 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1351 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1352 int> = 0> 1353 inline _LIBCPP_INLINE_VISIBILITY 1354 explicit constexpr variant( 1355 in_place_type_t<_Tp>, 1356 initializer_list<_Up> __il, 1357 _Args&&... __args) noexcept( 1358 is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>) 1359 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {} 1360 1361 ~variant() = default; 1362 1363 variant& operator=(const variant&) = default; 1364 variant& operator=(variant&&) = default; 1365 1366 template < 1367 class _Arg, 1368 enable_if_t<!is_same_v<__uncvref_t<_Arg>, variant>, int> = 0, 1369 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1370 size_t _Ip = 1371 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1372 enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>, 1373 int> = 0> 1374 inline _LIBCPP_INLINE_VISIBILITY 1375 variant& operator=(_Arg&& __arg) noexcept( 1376 is_nothrow_assignable_v<_Tp&, _Arg> && 1377 is_nothrow_constructible_v<_Tp, _Arg>) { 1378 __impl.template __assign<_Ip>(_VSTD::forward<_Arg>(__arg)); 1379 return *this; 1380 } 1381 1382 template < 1383 size_t _Ip, 1384 class... _Args, 1385 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1386 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1387 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1388 inline _LIBCPP_INLINE_VISIBILITY 1389 _Tp& emplace(_Args&&... __args) { 1390 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); 1391 } 1392 1393 template < 1394 size_t _Ip, 1395 class _Up, 1396 class... _Args, 1397 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1398 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1399 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1400 int> = 0> 1401 inline _LIBCPP_INLINE_VISIBILITY 1402 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1403 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); 1404 } 1405 1406 template < 1407 class _Tp, 1408 class... _Args, 1409 size_t _Ip = 1410 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1411 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1412 inline _LIBCPP_INLINE_VISIBILITY 1413 _Tp& emplace(_Args&&... __args) { 1414 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); 1415 } 1416 1417 template < 1418 class _Tp, 1419 class _Up, 1420 class... _Args, 1421 size_t _Ip = 1422 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1423 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1424 int> = 0> 1425 inline _LIBCPP_INLINE_VISIBILITY 1426 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1427 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); 1428 } 1429 1430 inline _LIBCPP_INLINE_VISIBILITY 1431 constexpr bool valueless_by_exception() const noexcept { 1432 return __impl.valueless_by_exception(); 1433 } 1434 1435 inline _LIBCPP_INLINE_VISIBILITY 1436 constexpr size_t index() const noexcept { return __impl.index(); } 1437 1438 template < 1439 bool _Dummy = true, 1440 enable_if_t< 1441 __all<( 1442 __dependent_type<is_move_constructible<_Types>, _Dummy>::value && 1443 __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value, 1444 int> = 0> 1445 inline _LIBCPP_INLINE_VISIBILITY 1446 void swap(variant& __that) noexcept( 1447 __all<(is_nothrow_move_constructible_v<_Types> && 1448 is_nothrow_swappable_v<_Types>)...>::value) { 1449 __impl.__swap(__that.__impl); 1450 } 1451 1452private: 1453 __variant_detail::__impl<_Types...> __impl; 1454 1455 friend struct __variant_detail::__access::__variant; 1456 friend struct __variant_detail::__visitation::__variant; 1457}; 1458 1459template <size_t _Ip, class... _Types> 1460inline _LIBCPP_INLINE_VISIBILITY 1461constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept { 1462 return __v.index() == _Ip; 1463} 1464 1465template <class _Tp, class... _Types> 1466inline _LIBCPP_INLINE_VISIBILITY 1467constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept { 1468 return __holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1469} 1470 1471template <size_t _Ip, class _Vp> 1472inline _LIBCPP_INLINE_VISIBILITY 1473_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1474constexpr auto&& __generic_get(_Vp&& __v) { 1475 using __variant_detail::__access::__variant; 1476 if (!__holds_alternative<_Ip>(__v)) { 1477 __throw_bad_variant_access(); 1478 } 1479 return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value; 1480} 1481 1482template <size_t _Ip, class... _Types> 1483inline _LIBCPP_INLINE_VISIBILITY 1484_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1485constexpr variant_alternative_t<_Ip, variant<_Types...>>& get( 1486 variant<_Types...>& __v) { 1487 static_assert(_Ip < sizeof...(_Types)); 1488 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1489 return __generic_get<_Ip>(__v); 1490} 1491 1492template <size_t _Ip, class... _Types> 1493inline _LIBCPP_INLINE_VISIBILITY 1494_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1495constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get( 1496 variant<_Types...>&& __v) { 1497 static_assert(_Ip < sizeof...(_Types)); 1498 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1499 return __generic_get<_Ip>(_VSTD::move(__v)); 1500} 1501 1502template <size_t _Ip, class... _Types> 1503inline _LIBCPP_INLINE_VISIBILITY 1504_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1505constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get( 1506 const variant<_Types...>& __v) { 1507 static_assert(_Ip < sizeof...(_Types)); 1508 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1509 return __generic_get<_Ip>(__v); 1510} 1511 1512template <size_t _Ip, class... _Types> 1513inline _LIBCPP_INLINE_VISIBILITY 1514_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1515constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get( 1516 const variant<_Types...>&& __v) { 1517 static_assert(_Ip < sizeof...(_Types)); 1518 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1519 return __generic_get<_Ip>(_VSTD::move(__v)); 1520} 1521 1522template <class _Tp, class... _Types> 1523inline _LIBCPP_INLINE_VISIBILITY 1524_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1525constexpr _Tp& get(variant<_Types...>& __v) { 1526 static_assert(!is_void_v<_Tp>); 1527 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1528} 1529 1530template <class _Tp, class... _Types> 1531inline _LIBCPP_INLINE_VISIBILITY 1532_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1533constexpr _Tp&& get(variant<_Types...>&& __v) { 1534 static_assert(!is_void_v<_Tp>); 1535 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1536 _VSTD::move(__v)); 1537} 1538 1539template <class _Tp, class... _Types> 1540inline _LIBCPP_INLINE_VISIBILITY 1541_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1542constexpr const _Tp& get(const variant<_Types...>& __v) { 1543 static_assert(!is_void_v<_Tp>); 1544 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1545} 1546 1547template <class _Tp, class... _Types> 1548inline _LIBCPP_INLINE_VISIBILITY 1549_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1550constexpr const _Tp&& get(const variant<_Types...>&& __v) { 1551 static_assert(!is_void_v<_Tp>); 1552 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1553 _VSTD::move(__v)); 1554} 1555 1556template <size_t _Ip, class _Vp> 1557inline _LIBCPP_INLINE_VISIBILITY 1558constexpr auto* __generic_get_if(_Vp* __v) noexcept { 1559 using __variant_detail::__access::__variant; 1560 return __v && __holds_alternative<_Ip>(*__v) 1561 ? _VSTD::addressof(__variant::__get_alt<_Ip>(*__v).__value) 1562 : nullptr; 1563} 1564 1565template <size_t _Ip, class... _Types> 1566inline _LIBCPP_INLINE_VISIBILITY 1567constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>> 1568get_if(variant<_Types...>* __v) noexcept { 1569 static_assert(_Ip < sizeof...(_Types)); 1570 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1571 return __generic_get_if<_Ip>(__v); 1572} 1573 1574template <size_t _Ip, class... _Types> 1575inline _LIBCPP_INLINE_VISIBILITY 1576constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>> 1577get_if(const variant<_Types...>* __v) noexcept { 1578 static_assert(_Ip < sizeof...(_Types)); 1579 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1580 return __generic_get_if<_Ip>(__v); 1581} 1582 1583template <class _Tp, class... _Types> 1584inline _LIBCPP_INLINE_VISIBILITY 1585constexpr add_pointer_t<_Tp> 1586get_if(variant<_Types...>* __v) noexcept { 1587 static_assert(!is_void_v<_Tp>); 1588 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1589} 1590 1591template <class _Tp, class... _Types> 1592inline _LIBCPP_INLINE_VISIBILITY 1593constexpr add_pointer_t<const _Tp> 1594get_if(const variant<_Types...>* __v) noexcept { 1595 static_assert(!is_void_v<_Tp>); 1596 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1597} 1598 1599template <class _Operator> 1600struct __convert_to_bool { 1601 template <class _T1, class _T2> 1602 _LIBCPP_INLINE_VISIBILITY constexpr bool operator()(_T1 && __t1, _T2&& __t2) const { 1603 static_assert(std::is_convertible<decltype(_Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2))), bool>::value, 1604 "the relational operator does not return a type which is implicitly convertible to bool"); 1605 return _Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2)); 1606 } 1607}; 1608 1609template <class... _Types> 1610inline _LIBCPP_INLINE_VISIBILITY 1611constexpr bool operator==(const variant<_Types...>& __lhs, 1612 const variant<_Types...>& __rhs) { 1613 using __variant_detail::__visitation::__variant; 1614 if (__lhs.index() != __rhs.index()) return false; 1615 if (__lhs.valueless_by_exception()) return true; 1616 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<equal_to<>>{}, __lhs, __rhs); 1617} 1618 1619template <class... _Types> 1620inline _LIBCPP_INLINE_VISIBILITY 1621constexpr bool operator!=(const variant<_Types...>& __lhs, 1622 const variant<_Types...>& __rhs) { 1623 using __variant_detail::__visitation::__variant; 1624 if (__lhs.index() != __rhs.index()) return true; 1625 if (__lhs.valueless_by_exception()) return false; 1626 return __variant::__visit_value_at( 1627 __lhs.index(), __convert_to_bool<not_equal_to<>>{}, __lhs, __rhs); 1628} 1629 1630template <class... _Types> 1631inline _LIBCPP_INLINE_VISIBILITY 1632constexpr bool operator<(const variant<_Types...>& __lhs, 1633 const variant<_Types...>& __rhs) { 1634 using __variant_detail::__visitation::__variant; 1635 if (__rhs.valueless_by_exception()) return false; 1636 if (__lhs.valueless_by_exception()) return true; 1637 if (__lhs.index() < __rhs.index()) return true; 1638 if (__lhs.index() > __rhs.index()) return false; 1639 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<less<>>{}, __lhs, __rhs); 1640} 1641 1642template <class... _Types> 1643inline _LIBCPP_INLINE_VISIBILITY 1644constexpr bool operator>(const variant<_Types...>& __lhs, 1645 const variant<_Types...>& __rhs) { 1646 using __variant_detail::__visitation::__variant; 1647 if (__lhs.valueless_by_exception()) return false; 1648 if (__rhs.valueless_by_exception()) return true; 1649 if (__lhs.index() > __rhs.index()) return true; 1650 if (__lhs.index() < __rhs.index()) return false; 1651 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<greater<>>{}, __lhs, __rhs); 1652} 1653 1654template <class... _Types> 1655inline _LIBCPP_INLINE_VISIBILITY 1656constexpr bool operator<=(const variant<_Types...>& __lhs, 1657 const variant<_Types...>& __rhs) { 1658 using __variant_detail::__visitation::__variant; 1659 if (__lhs.valueless_by_exception()) return true; 1660 if (__rhs.valueless_by_exception()) return false; 1661 if (__lhs.index() < __rhs.index()) return true; 1662 if (__lhs.index() > __rhs.index()) return false; 1663 return __variant::__visit_value_at( 1664 __lhs.index(), __convert_to_bool<less_equal<>>{}, __lhs, __rhs); 1665} 1666 1667template <class... _Types> 1668inline _LIBCPP_INLINE_VISIBILITY 1669constexpr bool operator>=(const variant<_Types...>& __lhs, 1670 const variant<_Types...>& __rhs) { 1671 using __variant_detail::__visitation::__variant; 1672 if (__rhs.valueless_by_exception()) return true; 1673 if (__lhs.valueless_by_exception()) return false; 1674 if (__lhs.index() > __rhs.index()) return true; 1675 if (__lhs.index() < __rhs.index()) return false; 1676 return __variant::__visit_value_at( 1677 __lhs.index(), __convert_to_bool<greater_equal<>>{}, __lhs, __rhs); 1678} 1679 1680template <class _Vis, class... _Vs> 1681inline _LIBCPP_INLINE_VISIBILITY 1682_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1683constexpr decltype(auto) visit(_Vis&& __vis, _Vs&&... __vs) { 1684 using __variant_detail::__visitation::__variant; 1685 return __variant::__visit_value(_VSTD::forward<_Vis>(__vis), 1686 _VSTD::forward<_Vs>(__vs)...); 1687} 1688 1689struct _LIBCPP_TEMPLATE_VIS monostate {}; 1690 1691inline _LIBCPP_INLINE_VISIBILITY 1692constexpr bool operator<(monostate, monostate) noexcept { return false; } 1693 1694inline _LIBCPP_INLINE_VISIBILITY 1695constexpr bool operator>(monostate, monostate) noexcept { return false; } 1696 1697inline _LIBCPP_INLINE_VISIBILITY 1698constexpr bool operator<=(monostate, monostate) noexcept { return true; } 1699 1700inline _LIBCPP_INLINE_VISIBILITY 1701constexpr bool operator>=(monostate, monostate) noexcept { return true; } 1702 1703inline _LIBCPP_INLINE_VISIBILITY 1704constexpr bool operator==(monostate, monostate) noexcept { return true; } 1705 1706inline _LIBCPP_INLINE_VISIBILITY 1707constexpr bool operator!=(monostate, monostate) noexcept { return false; } 1708 1709template <class... _Types> 1710inline _LIBCPP_INLINE_VISIBILITY 1711auto swap(variant<_Types...>& __lhs, 1712 variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs))) 1713 -> decltype(__lhs.swap(__rhs)) { 1714 __lhs.swap(__rhs); 1715} 1716 1717template <class... _Types> 1718struct _LIBCPP_TEMPLATE_VIS hash< 1719 __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> { 1720 using argument_type = variant<_Types...>; 1721 using result_type = size_t; 1722 1723 inline _LIBCPP_INLINE_VISIBILITY 1724 result_type operator()(const argument_type& __v) const { 1725 using __variant_detail::__visitation::__variant; 1726 size_t __res = 1727 __v.valueless_by_exception() 1728 ? 299792458 // Random value chosen by the universe upon creation 1729 : __variant::__visit_alt( 1730 [](const auto& __alt) { 1731 using __alt_type = __uncvref_t<decltype(__alt)>; 1732 using __value_type = remove_const_t< 1733 typename __alt_type::__value_type>; 1734 return hash<__value_type>{}(__alt.__value); 1735 }, 1736 __v); 1737 return __hash_combine(__res, hash<size_t>{}(__v.index())); 1738 } 1739}; 1740 1741template <> 1742struct _LIBCPP_TEMPLATE_VIS hash<monostate> { 1743 using argument_type = monostate; 1744 using result_type = size_t; 1745 1746 inline _LIBCPP_INLINE_VISIBILITY 1747 result_type operator()(const argument_type&) const _NOEXCEPT { 1748 return 66740831; // return a fundamentally attractive random value. 1749 } 1750}; 1751 1752#endif // _LIBCPP_STD_VER > 14 1753 1754_LIBCPP_END_NAMESPACE_STD 1755 1756_LIBCPP_POP_MACROS 1757 1758#endif // _LIBCPP_VARIANT 1759