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 template <class R, class Visitor, class... Variants> 173 constexpr R visit(Visitor&&, Variants&&...); // since C++20 174 175 // 20.7.7, class monostate 176 struct monostate; 177 178 // 20.7.8, monostate relational operators 179 constexpr bool operator<(monostate, monostate) noexcept; 180 constexpr bool operator>(monostate, monostate) noexcept; 181 constexpr bool operator<=(monostate, monostate) noexcept; 182 constexpr bool operator>=(monostate, monostate) noexcept; 183 constexpr bool operator==(monostate, monostate) noexcept; 184 constexpr bool operator!=(monostate, monostate) noexcept; 185 186 // 20.7.9, specialized algorithms 187 template <class... Types> 188 void swap(variant<Types...>&, variant<Types...>&) noexcept(see below); 189 190 // 20.7.10, class bad_variant_access 191 class bad_variant_access; 192 193 // 20.7.11, hash support 194 template <class T> struct hash; 195 template <class... Types> struct hash<variant<Types...>>; 196 template <> struct hash<monostate>; 197 198} // namespace std 199 200*/ 201 202#include <__availability> 203#include <__config> 204#include <__functional/hash.h> 205#include <__tuple> 206#include <__utility/forward.h> 207#include <__variant/monostate.h> 208#include <compare> 209#include <exception> 210#include <initializer_list> 211#include <limits> 212#include <new> 213#include <tuple> 214#include <type_traits> 215#include <utility> 216#include <version> 217 218#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 219#pragma GCC system_header 220#endif 221 222_LIBCPP_PUSH_MACROS 223#include <__undef_macros> 224 225namespace std { // explicitly not using versioning namespace 226 227class _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS bad_variant_access : public exception { 228public: 229 virtual const char* what() const _NOEXCEPT; 230}; 231 232} // namespace std 233 234_LIBCPP_BEGIN_NAMESPACE_STD 235 236// TODO: GCC 5 lies about its support for C++17 (it says it supports it but it 237// really doesn't). That breaks variant, which uses some C++17 features. 238// Remove this once we drop support for GCC 5. 239#if _LIBCPP_STD_VER > 14 && !(defined(_LIBCPP_COMPILER_GCC) && _GNUC_VER_NEW < 6000) 240 241// Light N-dimensional array of function pointers. Used in place of std::array to avoid 242// adding a dependency. 243template<class _Tp, size_t _Size> 244struct __farray { 245 static_assert(_Size > 0, "N-dimensional array should never be empty in std::visit"); 246 _Tp __buf_[_Size] = {}; 247 248 _LIBCPP_INLINE_VISIBILITY constexpr 249 const _Tp &operator[](size_t __n) const noexcept { 250 return __buf_[__n]; 251 } 252}; 253 254_LIBCPP_NORETURN 255inline _LIBCPP_INLINE_VISIBILITY 256_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 257void __throw_bad_variant_access() { 258#ifndef _LIBCPP_NO_EXCEPTIONS 259 throw bad_variant_access(); 260#else 261 _VSTD::abort(); 262#endif 263} 264 265template <class... _Types> 266class _LIBCPP_TEMPLATE_VIS variant; 267 268template <class _Tp> 269struct _LIBCPP_TEMPLATE_VIS variant_size; 270 271template <class _Tp> 272_LIBCPP_INLINE_VAR constexpr size_t variant_size_v = variant_size<_Tp>::value; 273 274template <class _Tp> 275struct _LIBCPP_TEMPLATE_VIS variant_size<const _Tp> : variant_size<_Tp> {}; 276 277template <class _Tp> 278struct _LIBCPP_TEMPLATE_VIS variant_size<volatile _Tp> : variant_size<_Tp> {}; 279 280template <class _Tp> 281struct _LIBCPP_TEMPLATE_VIS variant_size<const volatile _Tp> 282 : variant_size<_Tp> {}; 283 284template <class... _Types> 285struct _LIBCPP_TEMPLATE_VIS variant_size<variant<_Types...>> 286 : integral_constant<size_t, sizeof...(_Types)> {}; 287 288template <size_t _Ip, class _Tp> 289struct _LIBCPP_TEMPLATE_VIS variant_alternative; 290 291template <size_t _Ip, class _Tp> 292using variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type; 293 294template <size_t _Ip, class _Tp> 295struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const _Tp> 296 : add_const<variant_alternative_t<_Ip, _Tp>> {}; 297 298template <size_t _Ip, class _Tp> 299struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, volatile _Tp> 300 : add_volatile<variant_alternative_t<_Ip, _Tp>> {}; 301 302template <size_t _Ip, class _Tp> 303struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const volatile _Tp> 304 : add_cv<variant_alternative_t<_Ip, _Tp>> {}; 305 306template <size_t _Ip, class... _Types> 307struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, variant<_Types...>> { 308 static_assert(_Ip < sizeof...(_Types), "Index out of bounds in std::variant_alternative<>"); 309 using type = __type_pack_element<_Ip, _Types...>; 310}; 311 312_LIBCPP_INLINE_VAR constexpr size_t variant_npos = static_cast<size_t>(-1); 313 314constexpr int __choose_index_type(unsigned int __num_elem) { 315 if (__num_elem < numeric_limits<unsigned char>::max()) 316 return 0; 317 if (__num_elem < numeric_limits<unsigned short>::max()) 318 return 1; 319 return 2; 320} 321 322template <size_t _NumAlts> 323using __variant_index_t = 324#ifndef _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION 325 unsigned int; 326#else 327 std::tuple_element_t< 328 __choose_index_type(_NumAlts), 329 std::tuple<unsigned char, unsigned short, unsigned int> 330 >; 331#endif 332 333template <class _IndexType> 334constexpr _IndexType __variant_npos = static_cast<_IndexType>(-1); 335 336template <class... _Types> 337class _LIBCPP_TEMPLATE_VIS variant; 338 339template <class... _Types> 340_LIBCPP_INLINE_VISIBILITY constexpr variant<_Types...>& 341__as_variant(variant<_Types...>& __vs) noexcept { 342 return __vs; 343} 344 345template <class... _Types> 346_LIBCPP_INLINE_VISIBILITY constexpr const variant<_Types...>& 347__as_variant(const variant<_Types...>& __vs) noexcept { 348 return __vs; 349} 350 351template <class... _Types> 352_LIBCPP_INLINE_VISIBILITY constexpr variant<_Types...>&& 353__as_variant(variant<_Types...>&& __vs) noexcept { 354 return _VSTD::move(__vs); 355} 356 357template <class... _Types> 358_LIBCPP_INLINE_VISIBILITY constexpr const variant<_Types...>&& 359__as_variant(const variant<_Types...>&& __vs) noexcept { 360 return _VSTD::move(__vs); 361} 362 363namespace __find_detail { 364 365template <class _Tp, class... _Types> 366inline _LIBCPP_INLINE_VISIBILITY 367constexpr size_t __find_index() { 368 constexpr bool __matches[] = {is_same_v<_Tp, _Types>...}; 369 size_t __result = __not_found; 370 for (size_t __i = 0; __i < sizeof...(_Types); ++__i) { 371 if (__matches[__i]) { 372 if (__result != __not_found) { 373 return __ambiguous; 374 } 375 __result = __i; 376 } 377 } 378 return __result; 379} 380 381template <size_t _Index> 382struct __find_unambiguous_index_sfinae_impl 383 : integral_constant<size_t, _Index> {}; 384 385template <> 386struct __find_unambiguous_index_sfinae_impl<__not_found> {}; 387 388template <> 389struct __find_unambiguous_index_sfinae_impl<__ambiguous> {}; 390 391template <class _Tp, class... _Types> 392struct __find_unambiguous_index_sfinae 393 : __find_unambiguous_index_sfinae_impl<__find_index<_Tp, _Types...>()> {}; 394 395} // namespace __find_detail 396 397namespace __variant_detail { 398 399struct __valueless_t {}; 400 401enum class _Trait { _TriviallyAvailable, _Available, _Unavailable }; 402 403template <typename _Tp, 404 template <typename> class _IsTriviallyAvailable, 405 template <typename> class _IsAvailable> 406constexpr _Trait __trait = 407 _IsTriviallyAvailable<_Tp>::value 408 ? _Trait::_TriviallyAvailable 409 : _IsAvailable<_Tp>::value ? _Trait::_Available : _Trait::_Unavailable; 410 411inline _LIBCPP_INLINE_VISIBILITY 412constexpr _Trait __common_trait(initializer_list<_Trait> __traits) { 413 _Trait __result = _Trait::_TriviallyAvailable; 414 for (_Trait __t : __traits) { 415 if (static_cast<int>(__t) > static_cast<int>(__result)) { 416 __result = __t; 417 } 418 } 419 return __result; 420} 421 422template <typename... _Types> 423struct __traits { 424 static constexpr _Trait __copy_constructible_trait = 425 __common_trait({__trait<_Types, 426 is_trivially_copy_constructible, 427 is_copy_constructible>...}); 428 429 static constexpr _Trait __move_constructible_trait = 430 __common_trait({__trait<_Types, 431 is_trivially_move_constructible, 432 is_move_constructible>...}); 433 434 static constexpr _Trait __copy_assignable_trait = __common_trait( 435 {__copy_constructible_trait, 436 __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...}); 437 438 static constexpr _Trait __move_assignable_trait = __common_trait( 439 {__move_constructible_trait, 440 __trait<_Types, is_trivially_move_assignable, is_move_assignable>...}); 441 442 static constexpr _Trait __destructible_trait = __common_trait( 443 {__trait<_Types, is_trivially_destructible, is_destructible>...}); 444}; 445 446namespace __access { 447 448struct __union { 449 template <class _Vp> 450 inline _LIBCPP_INLINE_VISIBILITY 451 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) { 452 return _VSTD::forward<_Vp>(__v).__head; 453 } 454 455 template <class _Vp, size_t _Ip> 456 inline _LIBCPP_INLINE_VISIBILITY 457 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) { 458 return __get_alt(_VSTD::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>); 459 } 460}; 461 462struct __base { 463 template <size_t _Ip, class _Vp> 464 inline _LIBCPP_INLINE_VISIBILITY 465 static constexpr auto&& __get_alt(_Vp&& __v) { 466 return __union::__get_alt(_VSTD::forward<_Vp>(__v).__data, 467 in_place_index<_Ip>); 468 } 469}; 470 471struct __variant { 472 template <size_t _Ip, class _Vp> 473 inline _LIBCPP_INLINE_VISIBILITY 474 static constexpr auto&& __get_alt(_Vp&& __v) { 475 return __base::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v).__impl); 476 } 477}; 478 479} // namespace __access 480 481namespace __visitation { 482 483struct __base { 484 template <class _Visitor, class... _Vs> 485 inline _LIBCPP_INLINE_VISIBILITY 486 static constexpr decltype(auto) 487 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 488 constexpr auto __fdiagonal = 489 __make_fdiagonal<_Visitor&&, 490 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>(); 491 return __fdiagonal[__index](_VSTD::forward<_Visitor>(__visitor), 492 _VSTD::forward<_Vs>(__vs).__as_base()...); 493 } 494 495 template <class _Visitor, class... _Vs> 496 inline _LIBCPP_INLINE_VISIBILITY 497 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, 498 _Vs&&... __vs) { 499 constexpr auto __fmatrix = 500 __make_fmatrix<_Visitor&&, 501 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>(); 502 return __at(__fmatrix, __vs.index()...)( 503 _VSTD::forward<_Visitor>(__visitor), 504 _VSTD::forward<_Vs>(__vs).__as_base()...); 505 } 506 507private: 508 template <class _Tp> 509 inline _LIBCPP_INLINE_VISIBILITY 510 static constexpr const _Tp& __at(const _Tp& __elem) { return __elem; } 511 512 template <class _Tp, size_t _Np, typename... _Indices> 513 inline _LIBCPP_INLINE_VISIBILITY 514 static constexpr auto&& __at(const __farray<_Tp, _Np>& __elems, 515 size_t __index, _Indices... __indices) { 516 return __at(__elems[__index], __indices...); 517 } 518 519 template <class _Fp, class... _Fs> 520 static constexpr void __std_visit_visitor_return_type_check() { 521 static_assert( 522 __all<is_same_v<_Fp, _Fs>...>::value, 523 "`std::visit` requires the visitor to have a single return type."); 524 } 525 526 template <class... _Fs> 527 inline _LIBCPP_INLINE_VISIBILITY 528 static constexpr auto __make_farray(_Fs&&... __fs) { 529 __std_visit_visitor_return_type_check<__uncvref_t<_Fs>...>(); 530 using __result = __farray<common_type_t<__uncvref_t<_Fs>...>, sizeof...(_Fs)>; 531 return __result{{_VSTD::forward<_Fs>(__fs)...}}; 532 } 533 534 template <size_t... _Is> 535 struct __dispatcher { 536 template <class _Fp, class... _Vs> 537 inline _LIBCPP_INLINE_VISIBILITY 538 static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) { 539 return _VSTD::__invoke_constexpr( 540 static_cast<_Fp>(__f), 541 __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...); 542 } 543 }; 544 545 template <class _Fp, class... _Vs, size_t... _Is> 546 inline _LIBCPP_INLINE_VISIBILITY 547 static constexpr auto __make_dispatch(index_sequence<_Is...>) { 548 return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>; 549 } 550 551 template <size_t _Ip, class _Fp, class... _Vs> 552 inline _LIBCPP_INLINE_VISIBILITY 553 static constexpr auto __make_fdiagonal_impl() { 554 return __make_dispatch<_Fp, _Vs...>( 555 index_sequence<(__identity<_Vs>{}, _Ip)...>{}); 556 } 557 558 template <class _Fp, class... _Vs, size_t... _Is> 559 inline _LIBCPP_INLINE_VISIBILITY 560 static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) { 561 return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...); 562 } 563 564 template <class _Fp, class _Vp, class... _Vs> 565 inline _LIBCPP_INLINE_VISIBILITY 566 static constexpr auto __make_fdiagonal() { 567 constexpr size_t _Np = __uncvref_t<_Vp>::__size(); 568 static_assert(__all<(_Np == __uncvref_t<_Vs>::__size())...>::value); 569 return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<_Np>{}); 570 } 571 572 template <class _Fp, class... _Vs, size_t... _Is> 573 inline _LIBCPP_INLINE_VISIBILITY 574 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) { 575 return __make_dispatch<_Fp, _Vs...>(__is); 576 } 577 578 template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls> 579 inline _LIBCPP_INLINE_VISIBILITY 580 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>, 581 index_sequence<_Js...>, 582 _Ls... __ls) { 583 return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>( 584 index_sequence<_Is..., _Js>{}, __ls...)...); 585 } 586 587 template <class _Fp, class... _Vs> 588 inline _LIBCPP_INLINE_VISIBILITY 589 static constexpr auto __make_fmatrix() { 590 return __make_fmatrix_impl<_Fp, _Vs...>( 591 index_sequence<>{}, make_index_sequence<__uncvref_t<_Vs>::__size()>{}...); 592 } 593}; 594 595struct __variant { 596 template <class _Visitor, class... _Vs> 597 inline _LIBCPP_INLINE_VISIBILITY 598 static constexpr decltype(auto) 599 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 600 return __base::__visit_alt_at(__index, 601 _VSTD::forward<_Visitor>(__visitor), 602 _VSTD::forward<_Vs>(__vs).__impl...); 603 } 604 605 template <class _Visitor, class... _Vs> 606 inline _LIBCPP_INLINE_VISIBILITY 607 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, 608 _Vs&&... __vs) { 609 return __base::__visit_alt( 610 _VSTD::forward<_Visitor>(__visitor), 611 _VSTD::__as_variant(_VSTD::forward<_Vs>(__vs)).__impl...); 612 } 613 614 template <class _Visitor, class... _Vs> 615 inline _LIBCPP_INLINE_VISIBILITY 616 static constexpr decltype(auto) 617 __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 618 return __visit_alt_at( 619 __index, 620 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)), 621 _VSTD::forward<_Vs>(__vs)...); 622 } 623 624 template <class _Visitor, class... _Vs> 625 inline _LIBCPP_INLINE_VISIBILITY 626 static constexpr decltype(auto) __visit_value(_Visitor&& __visitor, 627 _Vs&&... __vs) { 628 return __visit_alt( 629 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)), 630 _VSTD::forward<_Vs>(__vs)...); 631 } 632 633#if _LIBCPP_STD_VER > 17 634 template <class _Rp, class _Visitor, class... _Vs> 635 inline _LIBCPP_INLINE_VISIBILITY 636 static constexpr _Rp __visit_value(_Visitor&& __visitor, 637 _Vs&&... __vs) { 638 return __visit_alt( 639 __make_value_visitor<_Rp>(_VSTD::forward<_Visitor>(__visitor)), 640 _VSTD::forward<_Vs>(__vs)...); 641 } 642#endif 643 644private: 645 template <class _Visitor, class... _Values> 646 static constexpr void __std_visit_exhaustive_visitor_check() { 647 static_assert(is_invocable_v<_Visitor, _Values...>, 648 "`std::visit` requires the visitor to be exhaustive."); 649 } 650 651 template <class _Visitor> 652 struct __value_visitor { 653 template <class... _Alts> 654 inline _LIBCPP_INLINE_VISIBILITY 655 constexpr decltype(auto) operator()(_Alts&&... __alts) const { 656 __std_visit_exhaustive_visitor_check< 657 _Visitor, 658 decltype((_VSTD::forward<_Alts>(__alts).__value))...>(); 659 return _VSTD::__invoke_constexpr(_VSTD::forward<_Visitor>(__visitor), 660 _VSTD::forward<_Alts>(__alts).__value...); 661 } 662 _Visitor&& __visitor; 663 }; 664 665#if _LIBCPP_STD_VER > 17 666 template <class _Rp, class _Visitor> 667 struct __value_visitor_return_type { 668 template <class... _Alts> 669 inline _LIBCPP_INLINE_VISIBILITY 670 constexpr _Rp operator()(_Alts&&... __alts) const { 671 __std_visit_exhaustive_visitor_check< 672 _Visitor, 673 decltype((_VSTD::forward<_Alts>(__alts).__value))...>(); 674 if constexpr (is_void_v<_Rp>) { 675 _VSTD::__invoke_constexpr(_VSTD::forward<_Visitor>(__visitor), 676 _VSTD::forward<_Alts>(__alts).__value...); 677 } 678 else { 679 return _VSTD::__invoke_constexpr(_VSTD::forward<_Visitor>(__visitor), 680 _VSTD::forward<_Alts>(__alts).__value...); 681 } 682 } 683 684 _Visitor&& __visitor; 685 }; 686#endif 687 688 template <class _Visitor> 689 inline _LIBCPP_INLINE_VISIBILITY 690 static constexpr auto __make_value_visitor(_Visitor&& __visitor) { 691 return __value_visitor<_Visitor>{_VSTD::forward<_Visitor>(__visitor)}; 692 } 693 694#if _LIBCPP_STD_VER > 17 695 template <class _Rp, class _Visitor> 696 inline _LIBCPP_INLINE_VISIBILITY 697 static constexpr auto __make_value_visitor(_Visitor&& __visitor) { 698 return __value_visitor_return_type<_Rp, _Visitor>{_VSTD::forward<_Visitor>(__visitor)}; 699 } 700#endif 701}; 702 703} // namespace __visitation 704 705template <size_t _Index, class _Tp> 706struct _LIBCPP_TEMPLATE_VIS __alt { 707 using __value_type = _Tp; 708 709 template <class... _Args> 710 inline _LIBCPP_INLINE_VISIBILITY 711 explicit constexpr __alt(in_place_t, _Args&&... __args) 712 : __value(_VSTD::forward<_Args>(__args)...) {} 713 714 __value_type __value; 715}; 716 717template <_Trait _DestructibleTrait, size_t _Index, class... _Types> 718union _LIBCPP_TEMPLATE_VIS __union; 719 720template <_Trait _DestructibleTrait, size_t _Index> 721union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {}; 722 723#define _LIBCPP_VARIANT_UNION(destructible_trait, destructor) \ 724 template <size_t _Index, class _Tp, class... _Types> \ 725 union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \ 726 _Index, \ 727 _Tp, \ 728 _Types...> { \ 729 public: \ 730 inline _LIBCPP_INLINE_VISIBILITY \ 731 explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \ 732 \ 733 template <class... _Args> \ 734 inline _LIBCPP_INLINE_VISIBILITY \ 735 explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \ 736 : __head(in_place, _VSTD::forward<_Args>(__args)...) {} \ 737 \ 738 template <size_t _Ip, class... _Args> \ 739 inline _LIBCPP_INLINE_VISIBILITY \ 740 explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \ 741 : __tail(in_place_index<_Ip - 1>, _VSTD::forward<_Args>(__args)...) {} \ 742 \ 743 __union(const __union&) = default; \ 744 __union(__union&&) = default; \ 745 \ 746 destructor \ 747 \ 748 __union& operator=(const __union&) = default; \ 749 __union& operator=(__union&&) = default; \ 750 \ 751 private: \ 752 char __dummy; \ 753 __alt<_Index, _Tp> __head; \ 754 __union<destructible_trait, _Index + 1, _Types...> __tail; \ 755 \ 756 friend struct __access::__union; \ 757 } 758 759_LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;); 760_LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {}); 761_LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;); 762 763#undef _LIBCPP_VARIANT_UNION 764 765template <_Trait _DestructibleTrait, class... _Types> 766class _LIBCPP_TEMPLATE_VIS __base { 767public: 768 using __index_t = __variant_index_t<sizeof...(_Types)>; 769 770 inline _LIBCPP_INLINE_VISIBILITY 771 explicit constexpr __base(__valueless_t tag) noexcept 772 : __data(tag), __index(__variant_npos<__index_t>) {} 773 774 template <size_t _Ip, class... _Args> 775 inline _LIBCPP_INLINE_VISIBILITY 776 explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args) 777 : 778 __data(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...), 779 __index(_Ip) {} 780 781 inline _LIBCPP_INLINE_VISIBILITY 782 constexpr bool valueless_by_exception() const noexcept { 783 return index() == variant_npos; 784 } 785 786 inline _LIBCPP_INLINE_VISIBILITY 787 constexpr size_t index() const noexcept { 788 return __index == __variant_npos<__index_t> ? variant_npos : __index; 789 } 790 791protected: 792 inline _LIBCPP_INLINE_VISIBILITY 793 constexpr auto&& __as_base() & { return *this; } 794 795 inline _LIBCPP_INLINE_VISIBILITY 796 constexpr auto&& __as_base() && { return _VSTD::move(*this); } 797 798 inline _LIBCPP_INLINE_VISIBILITY 799 constexpr auto&& __as_base() const & { return *this; } 800 801 inline _LIBCPP_INLINE_VISIBILITY 802 constexpr auto&& __as_base() const && { return _VSTD::move(*this); } 803 804 inline _LIBCPP_INLINE_VISIBILITY 805 static constexpr size_t __size() { return sizeof...(_Types); } 806 807 __union<_DestructibleTrait, 0, _Types...> __data; 808 __index_t __index; 809 810 friend struct __access::__base; 811 friend struct __visitation::__base; 812}; 813 814template <class _Traits, _Trait = _Traits::__destructible_trait> 815class _LIBCPP_TEMPLATE_VIS __dtor; 816 817#define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy) \ 818 template <class... _Types> \ 819 class _LIBCPP_TEMPLATE_VIS __dtor<__traits<_Types...>, \ 820 destructible_trait> \ 821 : public __base<destructible_trait, _Types...> { \ 822 using __base_type = __base<destructible_trait, _Types...>; \ 823 using __index_t = typename __base_type::__index_t; \ 824 \ 825 public: \ 826 using __base_type::__base_type; \ 827 using __base_type::operator=; \ 828 \ 829 __dtor(const __dtor&) = default; \ 830 __dtor(__dtor&&) = default; \ 831 destructor \ 832 __dtor& operator=(const __dtor&) = default; \ 833 __dtor& operator=(__dtor&&) = default; \ 834 \ 835 protected: \ 836 inline _LIBCPP_INLINE_VISIBILITY \ 837 destroy \ 838 } 839 840_LIBCPP_VARIANT_DESTRUCTOR( 841 _Trait::_TriviallyAvailable, 842 ~__dtor() = default;, 843 void __destroy() noexcept { this->__index = __variant_npos<__index_t>; }); 844 845_LIBCPP_VARIANT_DESTRUCTOR( 846 _Trait::_Available, 847 ~__dtor() { __destroy(); }, 848 void __destroy() noexcept { 849 if (!this->valueless_by_exception()) { 850 __visitation::__base::__visit_alt( 851 [](auto& __alt) noexcept { 852 using __alt_type = __uncvref_t<decltype(__alt)>; 853 __alt.~__alt_type(); 854 }, 855 *this); 856 } 857 this->__index = __variant_npos<__index_t>; 858 }); 859 860_LIBCPP_VARIANT_DESTRUCTOR( 861 _Trait::_Unavailable, 862 ~__dtor() = delete;, 863 void __destroy() noexcept = delete;); 864 865#undef _LIBCPP_VARIANT_DESTRUCTOR 866 867template <class _Traits> 868class _LIBCPP_TEMPLATE_VIS __ctor : public __dtor<_Traits> { 869 using __base_type = __dtor<_Traits>; 870 871public: 872 using __base_type::__base_type; 873 using __base_type::operator=; 874 875protected: 876 template <size_t _Ip, class _Tp, class... _Args> 877 inline _LIBCPP_INLINE_VISIBILITY 878 static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) { 879 ::new ((void*)_VSTD::addressof(__a)) 880 __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...); 881 return __a.__value; 882 } 883 884 template <class _Rhs> 885 inline _LIBCPP_INLINE_VISIBILITY 886 static void __generic_construct(__ctor& __lhs, _Rhs&& __rhs) { 887 __lhs.__destroy(); 888 if (!__rhs.valueless_by_exception()) { 889 __visitation::__base::__visit_alt_at( 890 __rhs.index(), 891 [](auto& __lhs_alt, auto&& __rhs_alt) { 892 __construct_alt( 893 __lhs_alt, 894 _VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value); 895 }, 896 __lhs, _VSTD::forward<_Rhs>(__rhs)); 897 __lhs.__index = __rhs.index(); 898 } 899 } 900}; 901 902template <class _Traits, _Trait = _Traits::__move_constructible_trait> 903class _LIBCPP_TEMPLATE_VIS __move_constructor; 904 905#define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, \ 906 move_constructor) \ 907 template <class... _Types> \ 908 class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>, \ 909 move_constructible_trait> \ 910 : public __ctor<__traits<_Types...>> { \ 911 using __base_type = __ctor<__traits<_Types...>>; \ 912 \ 913 public: \ 914 using __base_type::__base_type; \ 915 using __base_type::operator=; \ 916 \ 917 __move_constructor(const __move_constructor&) = default; \ 918 move_constructor \ 919 ~__move_constructor() = default; \ 920 __move_constructor& operator=(const __move_constructor&) = default; \ 921 __move_constructor& operator=(__move_constructor&&) = default; \ 922 } 923 924_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 925 _Trait::_TriviallyAvailable, 926 __move_constructor(__move_constructor&& __that) = default;); 927 928_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 929 _Trait::_Available, 930 __move_constructor(__move_constructor&& __that) noexcept( 931 __all<is_nothrow_move_constructible_v<_Types>...>::value) 932 : __move_constructor(__valueless_t{}) { 933 this->__generic_construct(*this, _VSTD::move(__that)); 934 }); 935 936_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 937 _Trait::_Unavailable, 938 __move_constructor(__move_constructor&&) = delete;); 939 940#undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR 941 942template <class _Traits, _Trait = _Traits::__copy_constructible_trait> 943class _LIBCPP_TEMPLATE_VIS __copy_constructor; 944 945#define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, \ 946 copy_constructor) \ 947 template <class... _Types> \ 948 class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \ 949 copy_constructible_trait> \ 950 : public __move_constructor<__traits<_Types...>> { \ 951 using __base_type = __move_constructor<__traits<_Types...>>; \ 952 \ 953 public: \ 954 using __base_type::__base_type; \ 955 using __base_type::operator=; \ 956 \ 957 copy_constructor \ 958 __copy_constructor(__copy_constructor&&) = default; \ 959 ~__copy_constructor() = default; \ 960 __copy_constructor& operator=(const __copy_constructor&) = default; \ 961 __copy_constructor& operator=(__copy_constructor&&) = default; \ 962 } 963 964_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 965 _Trait::_TriviallyAvailable, 966 __copy_constructor(const __copy_constructor& __that) = default;); 967 968_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 969 _Trait::_Available, 970 __copy_constructor(const __copy_constructor& __that) 971 : __copy_constructor(__valueless_t{}) { 972 this->__generic_construct(*this, __that); 973 }); 974 975_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 976 _Trait::_Unavailable, 977 __copy_constructor(const __copy_constructor&) = delete;); 978 979#undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR 980 981template <class _Traits> 982class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> { 983 using __base_type = __copy_constructor<_Traits>; 984 985public: 986 using __base_type::__base_type; 987 using __base_type::operator=; 988 989 template <size_t _Ip, class... _Args> 990 inline _LIBCPP_INLINE_VISIBILITY 991 auto& __emplace(_Args&&... __args) { 992 this->__destroy(); 993 auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this), 994 _VSTD::forward<_Args>(__args)...); 995 this->__index = _Ip; 996 return __res; 997 } 998 999protected: 1000 template <size_t _Ip, class _Tp, class _Arg> 1001 inline _LIBCPP_INLINE_VISIBILITY 1002 void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) { 1003 if (this->index() == _Ip) { 1004 __a.__value = _VSTD::forward<_Arg>(__arg); 1005 } else { 1006 struct { 1007 void operator()(true_type) const { 1008 __this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg)); 1009 } 1010 void operator()(false_type) const { 1011 __this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg))); 1012 } 1013 __assignment* __this; 1014 _Arg&& __arg; 1015 } __impl{this, _VSTD::forward<_Arg>(__arg)}; 1016 __impl(bool_constant<is_nothrow_constructible_v<_Tp, _Arg> || 1017 !is_nothrow_move_constructible_v<_Tp>>{}); 1018 } 1019 } 1020 1021 template <class _That> 1022 inline _LIBCPP_INLINE_VISIBILITY 1023 void __generic_assign(_That&& __that) { 1024 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 1025 // do nothing. 1026 } else if (__that.valueless_by_exception()) { 1027 this->__destroy(); 1028 } else { 1029 __visitation::__base::__visit_alt_at( 1030 __that.index(), 1031 [this](auto& __this_alt, auto&& __that_alt) { 1032 this->__assign_alt( 1033 __this_alt, 1034 _VSTD::forward<decltype(__that_alt)>(__that_alt).__value); 1035 }, 1036 *this, _VSTD::forward<_That>(__that)); 1037 } 1038 } 1039}; 1040 1041template <class _Traits, _Trait = _Traits::__move_assignable_trait> 1042class _LIBCPP_TEMPLATE_VIS __move_assignment; 1043 1044#define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, \ 1045 move_assignment) \ 1046 template <class... _Types> \ 1047 class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \ 1048 move_assignable_trait> \ 1049 : public __assignment<__traits<_Types...>> { \ 1050 using __base_type = __assignment<__traits<_Types...>>; \ 1051 \ 1052 public: \ 1053 using __base_type::__base_type; \ 1054 using __base_type::operator=; \ 1055 \ 1056 __move_assignment(const __move_assignment&) = default; \ 1057 __move_assignment(__move_assignment&&) = default; \ 1058 ~__move_assignment() = default; \ 1059 __move_assignment& operator=(const __move_assignment&) = default; \ 1060 move_assignment \ 1061 } 1062 1063_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 1064 _Trait::_TriviallyAvailable, 1065 __move_assignment& operator=(__move_assignment&& __that) = default;); 1066 1067_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 1068 _Trait::_Available, 1069 __move_assignment& operator=(__move_assignment&& __that) noexcept( 1070 __all<(is_nothrow_move_constructible_v<_Types> && 1071 is_nothrow_move_assignable_v<_Types>)...>::value) { 1072 this->__generic_assign(_VSTD::move(__that)); 1073 return *this; 1074 }); 1075 1076_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 1077 _Trait::_Unavailable, 1078 __move_assignment& operator=(__move_assignment&&) = delete;); 1079 1080#undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT 1081 1082template <class _Traits, _Trait = _Traits::__copy_assignable_trait> 1083class _LIBCPP_TEMPLATE_VIS __copy_assignment; 1084 1085#define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, \ 1086 copy_assignment) \ 1087 template <class... _Types> \ 1088 class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \ 1089 copy_assignable_trait> \ 1090 : public __move_assignment<__traits<_Types...>> { \ 1091 using __base_type = __move_assignment<__traits<_Types...>>; \ 1092 \ 1093 public: \ 1094 using __base_type::__base_type; \ 1095 using __base_type::operator=; \ 1096 \ 1097 __copy_assignment(const __copy_assignment&) = default; \ 1098 __copy_assignment(__copy_assignment&&) = default; \ 1099 ~__copy_assignment() = default; \ 1100 copy_assignment \ 1101 __copy_assignment& operator=(__copy_assignment&&) = default; \ 1102 } 1103 1104_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1105 _Trait::_TriviallyAvailable, 1106 __copy_assignment& operator=(const __copy_assignment& __that) = default;); 1107 1108_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1109 _Trait::_Available, 1110 __copy_assignment& operator=(const __copy_assignment& __that) { 1111 this->__generic_assign(__that); 1112 return *this; 1113 }); 1114 1115_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1116 _Trait::_Unavailable, 1117 __copy_assignment& operator=(const __copy_assignment&) = delete;); 1118 1119#undef _LIBCPP_VARIANT_COPY_ASSIGNMENT 1120 1121template <class... _Types> 1122class _LIBCPP_TEMPLATE_VIS __impl 1123 : public __copy_assignment<__traits<_Types...>> { 1124 using __base_type = __copy_assignment<__traits<_Types...>>; 1125 1126public: 1127 using __base_type::__base_type; 1128 using __base_type::operator=; 1129 1130 template <size_t _Ip, class _Arg> 1131 inline _LIBCPP_INLINE_VISIBILITY 1132 void __assign(_Arg&& __arg) { 1133 this->__assign_alt(__access::__base::__get_alt<_Ip>(*this), 1134 _VSTD::forward<_Arg>(__arg)); 1135 } 1136 1137 inline _LIBCPP_INLINE_VISIBILITY 1138 void __swap(__impl& __that) { 1139 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 1140 // do nothing. 1141 } else if (this->index() == __that.index()) { 1142 __visitation::__base::__visit_alt_at( 1143 this->index(), 1144 [](auto& __this_alt, auto& __that_alt) { 1145 using _VSTD::swap; 1146 swap(__this_alt.__value, __that_alt.__value); 1147 }, 1148 *this, 1149 __that); 1150 } else { 1151 __impl* __lhs = this; 1152 __impl* __rhs = _VSTD::addressof(__that); 1153 if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) { 1154 _VSTD::swap(__lhs, __rhs); 1155 } 1156 __impl __tmp(_VSTD::move(*__rhs)); 1157#ifndef _LIBCPP_NO_EXCEPTIONS 1158 if constexpr (__all<is_nothrow_move_constructible_v<_Types>...>::value) { 1159 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1160 } else { 1161 // EXTENSION: When the move construction of `__lhs` into `__rhs` throws 1162 // and `__tmp` is nothrow move constructible then we move `__tmp` back 1163 // into `__rhs` and provide the strong exception safety guarantee. 1164 try { 1165 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1166 } catch (...) { 1167 if (__tmp.__move_nothrow()) { 1168 this->__generic_construct(*__rhs, _VSTD::move(__tmp)); 1169 } 1170 throw; 1171 } 1172 } 1173#else 1174 // this isn't consolidated with the `if constexpr` branch above due to 1175 // `throw` being ill-formed with exceptions disabled even when discarded. 1176 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1177#endif 1178 this->__generic_construct(*__lhs, _VSTD::move(__tmp)); 1179 } 1180 } 1181 1182private: 1183 inline _LIBCPP_INLINE_VISIBILITY 1184 bool __move_nothrow() const { 1185 constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...}; 1186 return this->valueless_by_exception() || __results[this->index()]; 1187 } 1188}; 1189 1190struct __no_narrowing_check { 1191 template <class _Dest, class _Source> 1192 using _Apply = __identity<_Dest>; 1193}; 1194 1195struct __narrowing_check { 1196 template <class _Dest> 1197 static auto __test_impl(_Dest (&&)[1]) -> __identity<_Dest>; 1198 template <class _Dest, class _Source> 1199 using _Apply _LIBCPP_NODEBUG_TYPE = decltype(__test_impl<_Dest>({declval<_Source>()})); 1200}; 1201 1202template <class _Dest, class _Source> 1203using __check_for_narrowing _LIBCPP_NODEBUG_TYPE = 1204 typename _If< 1205#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT 1206 false && 1207#endif 1208 is_arithmetic<_Dest>::value, 1209 __narrowing_check, 1210 __no_narrowing_check 1211 >::template _Apply<_Dest, _Source>; 1212 1213template <class _Tp, size_t _Idx> 1214struct __overload { 1215 template <class _Up> 1216 auto operator()(_Tp, _Up&&) const -> __check_for_narrowing<_Tp, _Up>; 1217}; 1218 1219template <class _Tp, size_t> 1220struct __overload_bool { 1221 template <class _Up, class _Ap = __uncvref_t<_Up>> 1222 auto operator()(bool, _Up&&) const 1223 -> enable_if_t<is_same_v<_Ap, bool>, __identity<_Tp>>; 1224}; 1225 1226template <size_t _Idx> 1227struct __overload<bool, _Idx> : __overload_bool<bool, _Idx> {}; 1228template <size_t _Idx> 1229struct __overload<bool const, _Idx> : __overload_bool<bool const, _Idx> {}; 1230template <size_t _Idx> 1231struct __overload<bool volatile, _Idx> : __overload_bool<bool volatile, _Idx> {}; 1232template <size_t _Idx> 1233struct __overload<bool const volatile, _Idx> : __overload_bool<bool const volatile, _Idx> {}; 1234 1235template <class ..._Bases> 1236struct __all_overloads : _Bases... { 1237 void operator()() const; 1238 using _Bases::operator()...; 1239}; 1240 1241template <class IdxSeq> 1242struct __make_overloads_imp; 1243 1244template <size_t ..._Idx> 1245struct __make_overloads_imp<__tuple_indices<_Idx...> > { 1246 template <class ..._Types> 1247 using _Apply _LIBCPP_NODEBUG_TYPE = __all_overloads<__overload<_Types, _Idx>...>; 1248}; 1249 1250template <class ..._Types> 1251using _MakeOverloads _LIBCPP_NODEBUG_TYPE = typename __make_overloads_imp< 1252 __make_indices_imp<sizeof...(_Types), 0> >::template _Apply<_Types...>; 1253 1254template <class _Tp, class... _Types> 1255using __best_match_t = 1256 typename invoke_result_t<_MakeOverloads<_Types...>, _Tp, _Tp>::type; 1257 1258} // __variant_detail 1259 1260template <class... _Types> 1261class _LIBCPP_TEMPLATE_VIS variant 1262 : private __sfinae_ctor_base< 1263 __all<is_copy_constructible_v<_Types>...>::value, 1264 __all<is_move_constructible_v<_Types>...>::value>, 1265 private __sfinae_assign_base< 1266 __all<(is_copy_constructible_v<_Types> && 1267 is_copy_assignable_v<_Types>)...>::value, 1268 __all<(is_move_constructible_v<_Types> && 1269 is_move_assignable_v<_Types>)...>::value> { 1270 static_assert(0 < sizeof...(_Types), 1271 "variant must consist of at least one alternative."); 1272 1273 static_assert(__all<!is_array_v<_Types>...>::value, 1274 "variant can not have an array type as an alternative."); 1275 1276 static_assert(__all<!is_reference_v<_Types>...>::value, 1277 "variant can not have a reference type as an alternative."); 1278 1279 static_assert(__all<!is_void_v<_Types>...>::value, 1280 "variant can not have a void type as an alternative."); 1281 1282 using __first_type = variant_alternative_t<0, variant>; 1283 1284public: 1285 template <bool _Dummy = true, 1286 enable_if_t<__dependent_type<is_default_constructible<__first_type>, 1287 _Dummy>::value, 1288 int> = 0> 1289 inline _LIBCPP_INLINE_VISIBILITY 1290 constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>) 1291 : __impl(in_place_index<0>) {} 1292 1293 variant(const variant&) = default; 1294 variant(variant&&) = default; 1295 1296 template < 1297 class _Arg, 1298 enable_if_t<!is_same_v<__uncvref_t<_Arg>, variant>, int> = 0, 1299 enable_if_t<!__is_inplace_type<__uncvref_t<_Arg>>::value, int> = 0, 1300 enable_if_t<!__is_inplace_index<__uncvref_t<_Arg>>::value, int> = 0, 1301 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1302 size_t _Ip = 1303 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1304 enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0> 1305 inline _LIBCPP_INLINE_VISIBILITY 1306 constexpr variant(_Arg&& __arg) noexcept( 1307 is_nothrow_constructible_v<_Tp, _Arg>) 1308 : __impl(in_place_index<_Ip>, _VSTD::forward<_Arg>(__arg)) {} 1309 1310 template <size_t _Ip, class... _Args, 1311 class = enable_if_t<(_Ip < sizeof...(_Types)), int>, 1312 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1313 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1314 inline _LIBCPP_INLINE_VISIBILITY 1315 explicit constexpr variant( 1316 in_place_index_t<_Ip>, 1317 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>) 1318 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {} 1319 1320 template < 1321 size_t _Ip, 1322 class _Up, 1323 class... _Args, 1324 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1325 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1326 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1327 int> = 0> 1328 inline _LIBCPP_INLINE_VISIBILITY 1329 explicit constexpr variant( 1330 in_place_index_t<_Ip>, 1331 initializer_list<_Up> __il, 1332 _Args&&... __args) noexcept( 1333 is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) 1334 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {} 1335 1336 template < 1337 class _Tp, 1338 class... _Args, 1339 size_t _Ip = 1340 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1341 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1342 inline _LIBCPP_INLINE_VISIBILITY 1343 explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept( 1344 is_nothrow_constructible_v<_Tp, _Args...>) 1345 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {} 1346 1347 template < 1348 class _Tp, 1349 class _Up, 1350 class... _Args, 1351 size_t _Ip = 1352 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1353 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1354 int> = 0> 1355 inline _LIBCPP_INLINE_VISIBILITY 1356 explicit constexpr variant( 1357 in_place_type_t<_Tp>, 1358 initializer_list<_Up> __il, 1359 _Args&&... __args) noexcept( 1360 is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>) 1361 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {} 1362 1363 ~variant() = default; 1364 1365 variant& operator=(const variant&) = default; 1366 variant& operator=(variant&&) = default; 1367 1368 template < 1369 class _Arg, 1370 enable_if_t<!is_same_v<__uncvref_t<_Arg>, variant>, int> = 0, 1371 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1372 size_t _Ip = 1373 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1374 enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>, 1375 int> = 0> 1376 inline _LIBCPP_INLINE_VISIBILITY 1377 variant& operator=(_Arg&& __arg) noexcept( 1378 is_nothrow_assignable_v<_Tp&, _Arg> && 1379 is_nothrow_constructible_v<_Tp, _Arg>) { 1380 __impl.template __assign<_Ip>(_VSTD::forward<_Arg>(__arg)); 1381 return *this; 1382 } 1383 1384 template < 1385 size_t _Ip, 1386 class... _Args, 1387 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1388 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1389 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1390 inline _LIBCPP_INLINE_VISIBILITY 1391 _Tp& emplace(_Args&&... __args) { 1392 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); 1393 } 1394 1395 template < 1396 size_t _Ip, 1397 class _Up, 1398 class... _Args, 1399 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1400 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1401 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1402 int> = 0> 1403 inline _LIBCPP_INLINE_VISIBILITY 1404 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1405 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); 1406 } 1407 1408 template < 1409 class _Tp, 1410 class... _Args, 1411 size_t _Ip = 1412 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1413 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1414 inline _LIBCPP_INLINE_VISIBILITY 1415 _Tp& emplace(_Args&&... __args) { 1416 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); 1417 } 1418 1419 template < 1420 class _Tp, 1421 class _Up, 1422 class... _Args, 1423 size_t _Ip = 1424 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1425 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1426 int> = 0> 1427 inline _LIBCPP_INLINE_VISIBILITY 1428 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1429 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); 1430 } 1431 1432 inline _LIBCPP_INLINE_VISIBILITY 1433 constexpr bool valueless_by_exception() const noexcept { 1434 return __impl.valueless_by_exception(); 1435 } 1436 1437 inline _LIBCPP_INLINE_VISIBILITY 1438 constexpr size_t index() const noexcept { return __impl.index(); } 1439 1440 template < 1441 bool _Dummy = true, 1442 enable_if_t< 1443 __all<( 1444 __dependent_type<is_move_constructible<_Types>, _Dummy>::value && 1445 __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value, 1446 int> = 0> 1447 inline _LIBCPP_INLINE_VISIBILITY 1448 void swap(variant& __that) noexcept( 1449 __all<(is_nothrow_move_constructible_v<_Types> && 1450 is_nothrow_swappable_v<_Types>)...>::value) { 1451 __impl.__swap(__that.__impl); 1452 } 1453 1454private: 1455 __variant_detail::__impl<_Types...> __impl; 1456 1457 friend struct __variant_detail::__access::__variant; 1458 friend struct __variant_detail::__visitation::__variant; 1459}; 1460 1461template <size_t _Ip, class... _Types> 1462inline _LIBCPP_INLINE_VISIBILITY 1463constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept { 1464 return __v.index() == _Ip; 1465} 1466 1467template <class _Tp, class... _Types> 1468inline _LIBCPP_INLINE_VISIBILITY 1469constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept { 1470 return __holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1471} 1472 1473template <size_t _Ip, class _Vp> 1474inline _LIBCPP_INLINE_VISIBILITY 1475_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1476constexpr auto&& __generic_get(_Vp&& __v) { 1477 using __variant_detail::__access::__variant; 1478 if (!__holds_alternative<_Ip>(__v)) { 1479 __throw_bad_variant_access(); 1480 } 1481 return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value; 1482} 1483 1484template <size_t _Ip, class... _Types> 1485inline _LIBCPP_INLINE_VISIBILITY 1486_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1487constexpr variant_alternative_t<_Ip, variant<_Types...>>& get( 1488 variant<_Types...>& __v) { 1489 static_assert(_Ip < sizeof...(_Types)); 1490 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1491 return __generic_get<_Ip>(__v); 1492} 1493 1494template <size_t _Ip, class... _Types> 1495inline _LIBCPP_INLINE_VISIBILITY 1496_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1497constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get( 1498 variant<_Types...>&& __v) { 1499 static_assert(_Ip < sizeof...(_Types)); 1500 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1501 return __generic_get<_Ip>(_VSTD::move(__v)); 1502} 1503 1504template <size_t _Ip, class... _Types> 1505inline _LIBCPP_INLINE_VISIBILITY 1506_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1507constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get( 1508 const variant<_Types...>& __v) { 1509 static_assert(_Ip < sizeof...(_Types)); 1510 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1511 return __generic_get<_Ip>(__v); 1512} 1513 1514template <size_t _Ip, class... _Types> 1515inline _LIBCPP_INLINE_VISIBILITY 1516_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1517constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get( 1518 const variant<_Types...>&& __v) { 1519 static_assert(_Ip < sizeof...(_Types)); 1520 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1521 return __generic_get<_Ip>(_VSTD::move(__v)); 1522} 1523 1524template <class _Tp, class... _Types> 1525inline _LIBCPP_INLINE_VISIBILITY 1526_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1527constexpr _Tp& get(variant<_Types...>& __v) { 1528 static_assert(!is_void_v<_Tp>); 1529 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1530} 1531 1532template <class _Tp, class... _Types> 1533inline _LIBCPP_INLINE_VISIBILITY 1534_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1535constexpr _Tp&& get(variant<_Types...>&& __v) { 1536 static_assert(!is_void_v<_Tp>); 1537 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1538 _VSTD::move(__v)); 1539} 1540 1541template <class _Tp, class... _Types> 1542inline _LIBCPP_INLINE_VISIBILITY 1543_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1544constexpr const _Tp& get(const variant<_Types...>& __v) { 1545 static_assert(!is_void_v<_Tp>); 1546 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1547} 1548 1549template <class _Tp, class... _Types> 1550inline _LIBCPP_INLINE_VISIBILITY 1551_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1552constexpr const _Tp&& get(const variant<_Types...>&& __v) { 1553 static_assert(!is_void_v<_Tp>); 1554 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1555 _VSTD::move(__v)); 1556} 1557 1558template <size_t _Ip, class _Vp> 1559inline _LIBCPP_INLINE_VISIBILITY 1560constexpr auto* __generic_get_if(_Vp* __v) noexcept { 1561 using __variant_detail::__access::__variant; 1562 return __v && __holds_alternative<_Ip>(*__v) 1563 ? _VSTD::addressof(__variant::__get_alt<_Ip>(*__v).__value) 1564 : nullptr; 1565} 1566 1567template <size_t _Ip, class... _Types> 1568inline _LIBCPP_INLINE_VISIBILITY 1569constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>> 1570get_if(variant<_Types...>* __v) noexcept { 1571 static_assert(_Ip < sizeof...(_Types)); 1572 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1573 return __generic_get_if<_Ip>(__v); 1574} 1575 1576template <size_t _Ip, class... _Types> 1577inline _LIBCPP_INLINE_VISIBILITY 1578constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>> 1579get_if(const variant<_Types...>* __v) noexcept { 1580 static_assert(_Ip < sizeof...(_Types)); 1581 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1582 return __generic_get_if<_Ip>(__v); 1583} 1584 1585template <class _Tp, class... _Types> 1586inline _LIBCPP_INLINE_VISIBILITY 1587constexpr add_pointer_t<_Tp> 1588get_if(variant<_Types...>* __v) noexcept { 1589 static_assert(!is_void_v<_Tp>); 1590 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1591} 1592 1593template <class _Tp, class... _Types> 1594inline _LIBCPP_INLINE_VISIBILITY 1595constexpr add_pointer_t<const _Tp> 1596get_if(const variant<_Types...>* __v) noexcept { 1597 static_assert(!is_void_v<_Tp>); 1598 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1599} 1600 1601template <class _Operator> 1602struct __convert_to_bool { 1603 template <class _T1, class _T2> 1604 _LIBCPP_INLINE_VISIBILITY constexpr bool operator()(_T1 && __t1, _T2&& __t2) const { 1605 static_assert(is_convertible<decltype(_Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2))), bool>::value, 1606 "the relational operator does not return a type which is implicitly convertible to bool"); 1607 return _Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2)); 1608 } 1609}; 1610 1611template <class... _Types> 1612inline _LIBCPP_INLINE_VISIBILITY 1613constexpr bool operator==(const variant<_Types...>& __lhs, 1614 const variant<_Types...>& __rhs) { 1615 using __variant_detail::__visitation::__variant; 1616 if (__lhs.index() != __rhs.index()) return false; 1617 if (__lhs.valueless_by_exception()) return true; 1618 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<equal_to<>>{}, __lhs, __rhs); 1619} 1620 1621template <class... _Types> 1622inline _LIBCPP_INLINE_VISIBILITY 1623constexpr bool operator!=(const variant<_Types...>& __lhs, 1624 const variant<_Types...>& __rhs) { 1625 using __variant_detail::__visitation::__variant; 1626 if (__lhs.index() != __rhs.index()) return true; 1627 if (__lhs.valueless_by_exception()) return false; 1628 return __variant::__visit_value_at( 1629 __lhs.index(), __convert_to_bool<not_equal_to<>>{}, __lhs, __rhs); 1630} 1631 1632template <class... _Types> 1633inline _LIBCPP_INLINE_VISIBILITY 1634constexpr bool operator<(const variant<_Types...>& __lhs, 1635 const variant<_Types...>& __rhs) { 1636 using __variant_detail::__visitation::__variant; 1637 if (__rhs.valueless_by_exception()) return false; 1638 if (__lhs.valueless_by_exception()) return true; 1639 if (__lhs.index() < __rhs.index()) return true; 1640 if (__lhs.index() > __rhs.index()) return false; 1641 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<less<>>{}, __lhs, __rhs); 1642} 1643 1644template <class... _Types> 1645inline _LIBCPP_INLINE_VISIBILITY 1646constexpr bool operator>(const variant<_Types...>& __lhs, 1647 const variant<_Types...>& __rhs) { 1648 using __variant_detail::__visitation::__variant; 1649 if (__lhs.valueless_by_exception()) return false; 1650 if (__rhs.valueless_by_exception()) return true; 1651 if (__lhs.index() > __rhs.index()) return true; 1652 if (__lhs.index() < __rhs.index()) return false; 1653 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<greater<>>{}, __lhs, __rhs); 1654} 1655 1656template <class... _Types> 1657inline _LIBCPP_INLINE_VISIBILITY 1658constexpr bool operator<=(const variant<_Types...>& __lhs, 1659 const variant<_Types...>& __rhs) { 1660 using __variant_detail::__visitation::__variant; 1661 if (__lhs.valueless_by_exception()) return true; 1662 if (__rhs.valueless_by_exception()) return false; 1663 if (__lhs.index() < __rhs.index()) return true; 1664 if (__lhs.index() > __rhs.index()) return false; 1665 return __variant::__visit_value_at( 1666 __lhs.index(), __convert_to_bool<less_equal<>>{}, __lhs, __rhs); 1667} 1668 1669template <class... _Types> 1670inline _LIBCPP_INLINE_VISIBILITY 1671constexpr bool operator>=(const variant<_Types...>& __lhs, 1672 const variant<_Types...>& __rhs) { 1673 using __variant_detail::__visitation::__variant; 1674 if (__rhs.valueless_by_exception()) return true; 1675 if (__lhs.valueless_by_exception()) return false; 1676 if (__lhs.index() > __rhs.index()) return true; 1677 if (__lhs.index() < __rhs.index()) return false; 1678 return __variant::__visit_value_at( 1679 __lhs.index(), __convert_to_bool<greater_equal<>>{}, __lhs, __rhs); 1680} 1681 1682template <class... _Vs> 1683inline _LIBCPP_INLINE_VISIBILITY 1684 _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr void 1685 __throw_if_valueless(_Vs&&... __vs) { 1686 const bool __valueless = 1687 (... || _VSTD::__as_variant(__vs).valueless_by_exception()); 1688 if (__valueless) { 1689 __throw_bad_variant_access(); 1690 } 1691} 1692 1693template < 1694 class _Visitor, class... _Vs, 1695 typename = void_t<decltype(_VSTD::__as_variant(declval<_Vs>()))...> > 1696inline _LIBCPP_INLINE_VISIBILITY 1697 _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr 1698 decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) { 1699 using __variant_detail::__visitation::__variant; 1700 _VSTD::__throw_if_valueless(_VSTD::forward<_Vs>(__vs)...); 1701 return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor), 1702 _VSTD::forward<_Vs>(__vs)...); 1703} 1704 1705#if _LIBCPP_STD_VER > 17 1706template < 1707 class _Rp, class _Visitor, class... _Vs, 1708 typename = void_t<decltype(_VSTD::__as_variant(declval<_Vs>()))...> > 1709inline _LIBCPP_INLINE_VISIBILITY 1710 _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr _Rp 1711 visit(_Visitor&& __visitor, _Vs&&... __vs) { 1712 using __variant_detail::__visitation::__variant; 1713 _VSTD::__throw_if_valueless(_VSTD::forward<_Vs>(__vs)...); 1714 return __variant::__visit_value<_Rp>(_VSTD::forward<_Visitor>(__visitor), 1715 _VSTD::forward<_Vs>(__vs)...); 1716} 1717#endif 1718 1719template <class... _Types> 1720inline _LIBCPP_INLINE_VISIBILITY 1721auto swap(variant<_Types...>& __lhs, 1722 variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs))) 1723 -> decltype(__lhs.swap(__rhs)) { 1724 __lhs.swap(__rhs); 1725} 1726 1727template <class... _Types> 1728struct _LIBCPP_TEMPLATE_VIS hash< 1729 __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> { 1730 using argument_type = variant<_Types...>; 1731 using result_type = size_t; 1732 1733 inline _LIBCPP_INLINE_VISIBILITY 1734 result_type operator()(const argument_type& __v) const { 1735 using __variant_detail::__visitation::__variant; 1736 size_t __res = 1737 __v.valueless_by_exception() 1738 ? 299792458 // Random value chosen by the universe upon creation 1739 : __variant::__visit_alt( 1740 [](const auto& __alt) { 1741 using __alt_type = __uncvref_t<decltype(__alt)>; 1742 using __value_type = remove_const_t< 1743 typename __alt_type::__value_type>; 1744 return hash<__value_type>{}(__alt.__value); 1745 }, 1746 __v); 1747 return __hash_combine(__res, hash<size_t>{}(__v.index())); 1748 } 1749}; 1750 1751// __unchecked_get is the same as std::get, except, it is UB to use it with the wrong 1752// type whereas std::get will throw or returning nullptr. This makes it faster than 1753// std::get. 1754template <size_t _Ip, class _Vp> 1755inline _LIBCPP_INLINE_VISIBILITY 1756constexpr auto&& __unchecked_get(_Vp&& __v) noexcept { 1757 using __variant_detail::__access::__variant; 1758 return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value; 1759} 1760 1761template <class _Tp, class... _Types> 1762inline _LIBCPP_INLINE_VISIBILITY 1763constexpr auto&& __unchecked_get(const variant<_Types...>& __v) noexcept { 1764 return __unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1765} 1766 1767template <class _Tp, class... _Types> 1768inline _LIBCPP_INLINE_VISIBILITY 1769constexpr auto&& __unchecked_get(variant<_Types...>& __v) noexcept { 1770 return __unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1771} 1772 1773#endif // _LIBCPP_STD_VER > 14 1774 1775_LIBCPP_END_NAMESPACE_STD 1776 1777_LIBCPP_POP_MACROS 1778 1779#endif // _LIBCPP_VARIANT 1780