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#if _LIBCPP_STD_VER > 14 231 232_LIBCPP_NORETURN 233inline _LIBCPP_INLINE_VISIBILITY 234_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 235void __throw_bad_variant_access() { 236#ifndef _LIBCPP_NO_EXCEPTIONS 237 throw bad_variant_access(); 238#else 239 _VSTD::abort(); 240#endif 241} 242 243template <class... _Types> 244class _LIBCPP_TEMPLATE_VIS variant; 245 246template <class _Tp> 247struct _LIBCPP_TEMPLATE_VIS variant_size; 248 249template <class _Tp> 250_LIBCPP_INLINE_VAR constexpr size_t variant_size_v = variant_size<_Tp>::value; 251 252template <class _Tp> 253struct _LIBCPP_TEMPLATE_VIS variant_size<const _Tp> : variant_size<_Tp> {}; 254 255template <class _Tp> 256struct _LIBCPP_TEMPLATE_VIS variant_size<volatile _Tp> : variant_size<_Tp> {}; 257 258template <class _Tp> 259struct _LIBCPP_TEMPLATE_VIS variant_size<const volatile _Tp> 260 : variant_size<_Tp> {}; 261 262template <class... _Types> 263struct _LIBCPP_TEMPLATE_VIS variant_size<variant<_Types...>> 264 : integral_constant<size_t, sizeof...(_Types)> {}; 265 266template <size_t _Ip, class _Tp> 267struct _LIBCPP_TEMPLATE_VIS variant_alternative; 268 269template <size_t _Ip, class _Tp> 270using variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type; 271 272template <size_t _Ip, class _Tp> 273struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const _Tp> 274 : add_const<variant_alternative_t<_Ip, _Tp>> {}; 275 276template <size_t _Ip, class _Tp> 277struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, volatile _Tp> 278 : add_volatile<variant_alternative_t<_Ip, _Tp>> {}; 279 280template <size_t _Ip, class _Tp> 281struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const volatile _Tp> 282 : add_cv<variant_alternative_t<_Ip, _Tp>> {}; 283 284template <size_t _Ip, class... _Types> 285struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, variant<_Types...>> { 286 static_assert(_Ip < sizeof...(_Types), "Index out of bounds in std::variant_alternative<>"); 287 using type = __type_pack_element<_Ip, _Types...>; 288}; 289 290_LIBCPP_INLINE_VAR constexpr size_t variant_npos = static_cast<size_t>(-1); 291 292constexpr int __choose_index_type(unsigned int __num_elem) { 293 if (__num_elem < std::numeric_limits<unsigned char>::max()) 294 return 0; 295 if (__num_elem < std::numeric_limits<unsigned short>::max()) 296 return 1; 297 return 2; 298} 299 300template <size_t _NumAlts> 301using __variant_index_t = 302#ifndef _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION 303 unsigned int; 304#else 305 std::tuple_element_t< 306 __choose_index_type(_NumAlts), 307 std::tuple<unsigned char, unsigned short, unsigned int> 308 >; 309#endif 310 311template <class _IndexType> 312constexpr _IndexType __variant_npos = static_cast<_IndexType>(-1); 313 314namespace __find_detail { 315 316template <class _Tp, class... _Types> 317inline _LIBCPP_INLINE_VISIBILITY 318constexpr size_t __find_index() { 319 constexpr bool __matches[] = {is_same_v<_Tp, _Types>...}; 320 size_t __result = __not_found; 321 for (size_t __i = 0; __i < sizeof...(_Types); ++__i) { 322 if (__matches[__i]) { 323 if (__result != __not_found) { 324 return __ambiguous; 325 } 326 __result = __i; 327 } 328 } 329 return __result; 330} 331 332template <size_t _Index> 333struct __find_unambiguous_index_sfinae_impl 334 : integral_constant<size_t, _Index> {}; 335 336template <> 337struct __find_unambiguous_index_sfinae_impl<__not_found> {}; 338 339template <> 340struct __find_unambiguous_index_sfinae_impl<__ambiguous> {}; 341 342template <class _Tp, class... _Types> 343struct __find_unambiguous_index_sfinae 344 : __find_unambiguous_index_sfinae_impl<__find_index<_Tp, _Types...>()> {}; 345 346} // namespace __find_detail 347 348namespace __variant_detail { 349 350struct __valueless_t {}; 351 352enum class _Trait { _TriviallyAvailable, _Available, _Unavailable }; 353 354template <typename _Tp, 355 template <typename> class _IsTriviallyAvailable, 356 template <typename> class _IsAvailable> 357constexpr _Trait __trait = 358 _IsTriviallyAvailable<_Tp>::value 359 ? _Trait::_TriviallyAvailable 360 : _IsAvailable<_Tp>::value ? _Trait::_Available : _Trait::_Unavailable; 361 362inline _LIBCPP_INLINE_VISIBILITY 363constexpr _Trait __common_trait(initializer_list<_Trait> __traits) { 364 _Trait __result = _Trait::_TriviallyAvailable; 365 for (_Trait __t : __traits) { 366 if (static_cast<int>(__t) > static_cast<int>(__result)) { 367 __result = __t; 368 } 369 } 370 return __result; 371} 372 373template <typename... _Types> 374struct __traits { 375 static constexpr _Trait __copy_constructible_trait = 376 __common_trait({__trait<_Types, 377 is_trivially_copy_constructible, 378 is_copy_constructible>...}); 379 380 static constexpr _Trait __move_constructible_trait = 381 __common_trait({__trait<_Types, 382 is_trivially_move_constructible, 383 is_move_constructible>...}); 384 385 static constexpr _Trait __copy_assignable_trait = __common_trait( 386 {__copy_constructible_trait, 387 __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...}); 388 389 static constexpr _Trait __move_assignable_trait = __common_trait( 390 {__move_constructible_trait, 391 __trait<_Types, is_trivially_move_assignable, is_move_assignable>...}); 392 393 static constexpr _Trait __destructible_trait = __common_trait( 394 {__trait<_Types, is_trivially_destructible, is_destructible>...}); 395}; 396 397namespace __access { 398 399struct __union { 400 template <class _Vp> 401 inline _LIBCPP_INLINE_VISIBILITY 402 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) { 403 return _VSTD::forward<_Vp>(__v).__head; 404 } 405 406 template <class _Vp, size_t _Ip> 407 inline _LIBCPP_INLINE_VISIBILITY 408 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) { 409 return __get_alt(_VSTD::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>); 410 } 411}; 412 413struct __base { 414 template <size_t _Ip, class _Vp> 415 inline _LIBCPP_INLINE_VISIBILITY 416 static constexpr auto&& __get_alt(_Vp&& __v) { 417 return __union::__get_alt(_VSTD::forward<_Vp>(__v).__data, 418 in_place_index<_Ip>); 419 } 420}; 421 422struct __variant { 423 template <size_t _Ip, class _Vp> 424 inline _LIBCPP_INLINE_VISIBILITY 425 static constexpr auto&& __get_alt(_Vp&& __v) { 426 return __base::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v).__impl); 427 } 428}; 429 430} // namespace __access 431 432namespace __visitation { 433 434struct __base { 435 template <class _Visitor, class... _Vs> 436 inline _LIBCPP_INLINE_VISIBILITY 437 static constexpr decltype(auto) 438 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 439 constexpr auto __fdiagonal = 440 __make_fdiagonal<_Visitor&&, 441 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>(); 442 return __fdiagonal[__index](_VSTD::forward<_Visitor>(__visitor), 443 _VSTD::forward<_Vs>(__vs).__as_base()...); 444 } 445 446 template <class _Visitor, class... _Vs> 447 inline _LIBCPP_INLINE_VISIBILITY 448 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, 449 _Vs&&... __vs) { 450 constexpr auto __fmatrix = 451 __make_fmatrix<_Visitor&&, 452 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>(); 453 return __at(__fmatrix, __vs.index()...)( 454 _VSTD::forward<_Visitor>(__visitor), 455 _VSTD::forward<_Vs>(__vs).__as_base()...); 456 } 457 458private: 459 template <class _Tp> 460 inline _LIBCPP_INLINE_VISIBILITY 461 static constexpr const _Tp& __at(const _Tp& __elem) { return __elem; } 462 463 template <class _Tp, size_t _Np, typename... _Indices> 464 inline _LIBCPP_INLINE_VISIBILITY 465 static constexpr auto&& __at(const array<_Tp, _Np>& __elems, 466 size_t __index, _Indices... __indices) { 467 return __at(__elems[__index], __indices...); 468 } 469 470 template <class _Fp, class... _Fs> 471 static constexpr void __std_visit_visitor_return_type_check() { 472 static_assert( 473 __all<is_same_v<_Fp, _Fs>...>::value, 474 "`std::visit` requires the visitor to have a single return type."); 475 } 476 477 template <class... _Fs> 478 inline _LIBCPP_INLINE_VISIBILITY 479 static constexpr auto __make_farray(_Fs&&... __fs) { 480 __std_visit_visitor_return_type_check<__uncvref_t<_Fs>...>(); 481 using __result = array<common_type_t<__uncvref_t<_Fs>...>, sizeof...(_Fs)>; 482 return __result{{_VSTD::forward<_Fs>(__fs)...}}; 483 } 484 485 template <std::size_t... _Is> 486 struct __dispatcher { 487 template <class _Fp, class... _Vs> 488 inline _LIBCPP_INLINE_VISIBILITY 489 static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) { 490 return __invoke_constexpr( 491 static_cast<_Fp>(__f), 492 __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...); 493 } 494 }; 495 496 template <class _Fp, class... _Vs, size_t... _Is> 497 inline _LIBCPP_INLINE_VISIBILITY 498 static constexpr auto __make_dispatch(index_sequence<_Is...>) { 499 return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>; 500 } 501 502 template <size_t _Ip, class _Fp, class... _Vs> 503 inline _LIBCPP_INLINE_VISIBILITY 504 static constexpr auto __make_fdiagonal_impl() { 505 return __make_dispatch<_Fp, _Vs...>( 506 index_sequence<(__identity<_Vs>{}, _Ip)...>{}); 507 } 508 509 template <class _Fp, class... _Vs, size_t... _Is> 510 inline _LIBCPP_INLINE_VISIBILITY 511 static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) { 512 return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...); 513 } 514 515 template <class _Fp, class _Vp, class... _Vs> 516 inline _LIBCPP_INLINE_VISIBILITY 517 static constexpr auto __make_fdiagonal() { 518 constexpr size_t _Np = __uncvref_t<_Vp>::__size(); 519 static_assert(__all<(_Np == __uncvref_t<_Vs>::__size())...>::value); 520 return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<_Np>{}); 521 } 522 523 template <class _Fp, class... _Vs, size_t... _Is> 524 inline _LIBCPP_INLINE_VISIBILITY 525 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) { 526 return __make_dispatch<_Fp, _Vs...>(__is); 527 } 528 529 template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls> 530 inline _LIBCPP_INLINE_VISIBILITY 531 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>, 532 index_sequence<_Js...>, 533 _Ls... __ls) { 534 return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>( 535 index_sequence<_Is..., _Js>{}, __ls...)...); 536 } 537 538 template <class _Fp, class... _Vs> 539 inline _LIBCPP_INLINE_VISIBILITY 540 static constexpr auto __make_fmatrix() { 541 return __make_fmatrix_impl<_Fp, _Vs...>( 542 index_sequence<>{}, make_index_sequence<__uncvref_t<_Vs>::__size()>{}...); 543 } 544}; 545 546struct __variant { 547 template <class _Visitor, class... _Vs> 548 inline _LIBCPP_INLINE_VISIBILITY 549 static constexpr decltype(auto) 550 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 551 return __base::__visit_alt_at(__index, 552 _VSTD::forward<_Visitor>(__visitor), 553 _VSTD::forward<_Vs>(__vs).__impl...); 554 } 555 556 template <class _Visitor, class... _Vs> 557 inline _LIBCPP_INLINE_VISIBILITY 558 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, 559 _Vs&&... __vs) { 560 return __base::__visit_alt(_VSTD::forward<_Visitor>(__visitor), 561 _VSTD::forward<_Vs>(__vs).__impl...); 562 } 563 564 template <class _Visitor, class... _Vs> 565 inline _LIBCPP_INLINE_VISIBILITY 566 static constexpr decltype(auto) 567 __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) { 568 return __visit_alt_at( 569 __index, 570 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)), 571 _VSTD::forward<_Vs>(__vs)...); 572 } 573 574 template <class _Visitor, class... _Vs> 575 inline _LIBCPP_INLINE_VISIBILITY 576 static constexpr decltype(auto) __visit_value(_Visitor&& __visitor, 577 _Vs&&... __vs) { 578 return __visit_alt( 579 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)), 580 _VSTD::forward<_Vs>(__vs)...); 581 } 582 583private: 584 template <class _Visitor, class... _Values> 585 static constexpr void __std_visit_exhaustive_visitor_check() { 586 static_assert(is_invocable_v<_Visitor, _Values...>, 587 "`std::visit` requires the visitor to be exhaustive."); 588 } 589 590 template <class _Visitor> 591 struct __value_visitor { 592 template <class... _Alts> 593 inline _LIBCPP_INLINE_VISIBILITY 594 constexpr decltype(auto) operator()(_Alts&&... __alts) const { 595 __std_visit_exhaustive_visitor_check< 596 _Visitor, 597 decltype((_VSTD::forward<_Alts>(__alts).__value))...>(); 598 return __invoke_constexpr(_VSTD::forward<_Visitor>(__visitor), 599 _VSTD::forward<_Alts>(__alts).__value...); 600 } 601 _Visitor&& __visitor; 602 }; 603 604 template <class _Visitor> 605 inline _LIBCPP_INLINE_VISIBILITY 606 static constexpr auto __make_value_visitor(_Visitor&& __visitor) { 607 return __value_visitor<_Visitor>{_VSTD::forward<_Visitor>(__visitor)}; 608 } 609}; 610 611} // namespace __visitation 612 613template <size_t _Index, class _Tp> 614struct _LIBCPP_TEMPLATE_VIS __alt { 615 using __value_type = _Tp; 616 617 template <class... _Args> 618 inline _LIBCPP_INLINE_VISIBILITY 619 explicit constexpr __alt(in_place_t, _Args&&... __args) 620 : __value(_VSTD::forward<_Args>(__args)...) {} 621 622 __value_type __value; 623}; 624 625template <_Trait _DestructibleTrait, size_t _Index, class... _Types> 626union _LIBCPP_TEMPLATE_VIS __union; 627 628template <_Trait _DestructibleTrait, size_t _Index> 629union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {}; 630 631#define _LIBCPP_VARIANT_UNION(destructible_trait, destructor) \ 632 template <size_t _Index, class _Tp, class... _Types> \ 633 union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \ 634 _Index, \ 635 _Tp, \ 636 _Types...> { \ 637 public: \ 638 inline _LIBCPP_INLINE_VISIBILITY \ 639 explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \ 640 \ 641 template <class... _Args> \ 642 inline _LIBCPP_INLINE_VISIBILITY \ 643 explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \ 644 : __head(in_place, _VSTD::forward<_Args>(__args)...) {} \ 645 \ 646 template <size_t _Ip, class... _Args> \ 647 inline _LIBCPP_INLINE_VISIBILITY \ 648 explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \ 649 : __tail(in_place_index<_Ip - 1>, _VSTD::forward<_Args>(__args)...) {} \ 650 \ 651 __union(const __union&) = default; \ 652 __union(__union&&) = default; \ 653 \ 654 destructor \ 655 \ 656 __union& operator=(const __union&) = default; \ 657 __union& operator=(__union&&) = default; \ 658 \ 659 private: \ 660 char __dummy; \ 661 __alt<_Index, _Tp> __head; \ 662 __union<destructible_trait, _Index + 1, _Types...> __tail; \ 663 \ 664 friend struct __access::__union; \ 665 } 666 667_LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;); 668_LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {}); 669_LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;); 670 671#undef _LIBCPP_VARIANT_UNION 672 673template <_Trait _DestructibleTrait, class... _Types> 674class _LIBCPP_TEMPLATE_VIS __base { 675public: 676 using __index_t = __variant_index_t<sizeof...(_Types)>; 677 678 inline _LIBCPP_INLINE_VISIBILITY 679 explicit constexpr __base(__valueless_t tag) noexcept 680 : __data(tag), __index(__variant_npos<__index_t>) {} 681 682 template <size_t _Ip, class... _Args> 683 inline _LIBCPP_INLINE_VISIBILITY 684 explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args) 685 : 686 __data(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...), 687 __index(_Ip) {} 688 689 inline _LIBCPP_INLINE_VISIBILITY 690 constexpr bool valueless_by_exception() const noexcept { 691 return index() == variant_npos; 692 } 693 694 inline _LIBCPP_INLINE_VISIBILITY 695 constexpr size_t index() const noexcept { 696 return __index == __variant_npos<__index_t> ? variant_npos : __index; 697 } 698 699protected: 700 inline _LIBCPP_INLINE_VISIBILITY 701 constexpr auto&& __as_base() & { return *this; } 702 703 inline _LIBCPP_INLINE_VISIBILITY 704 constexpr auto&& __as_base() && { return _VSTD::move(*this); } 705 706 inline _LIBCPP_INLINE_VISIBILITY 707 constexpr auto&& __as_base() const & { return *this; } 708 709 inline _LIBCPP_INLINE_VISIBILITY 710 constexpr auto&& __as_base() const && { return _VSTD::move(*this); } 711 712 inline _LIBCPP_INLINE_VISIBILITY 713 static constexpr size_t __size() { return sizeof...(_Types); } 714 715 __union<_DestructibleTrait, 0, _Types...> __data; 716 __index_t __index; 717 718 friend struct __access::__base; 719 friend struct __visitation::__base; 720}; 721 722template <class _Traits, _Trait = _Traits::__destructible_trait> 723class _LIBCPP_TEMPLATE_VIS __destructor; 724 725#define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy) \ 726 template <class... _Types> \ 727 class _LIBCPP_TEMPLATE_VIS __destructor<__traits<_Types...>, \ 728 destructible_trait> \ 729 : public __base<destructible_trait, _Types...> { \ 730 using __base_type = __base<destructible_trait, _Types...>; \ 731 using __index_t = typename __base_type::__index_t; \ 732 \ 733 public: \ 734 using __base_type::__base_type; \ 735 using __base_type::operator=; \ 736 \ 737 __destructor(const __destructor&) = default; \ 738 __destructor(__destructor&&) = default; \ 739 destructor \ 740 __destructor& operator=(const __destructor&) = default; \ 741 __destructor& operator=(__destructor&&) = default; \ 742 \ 743 protected: \ 744 inline _LIBCPP_INLINE_VISIBILITY \ 745 destroy \ 746 } 747 748_LIBCPP_VARIANT_DESTRUCTOR( 749 _Trait::_TriviallyAvailable, 750 ~__destructor() = default;, 751 void __destroy() noexcept { this->__index = __variant_npos<__index_t>; }); 752 753_LIBCPP_VARIANT_DESTRUCTOR( 754 _Trait::_Available, 755 ~__destructor() { __destroy(); }, 756 void __destroy() noexcept { 757 if (!this->valueless_by_exception()) { 758 __visitation::__base::__visit_alt( 759 [](auto& __alt) noexcept { 760 using __alt_type = __uncvref_t<decltype(__alt)>; 761 __alt.~__alt_type(); 762 }, 763 *this); 764 } 765 this->__index = __variant_npos<__index_t>; 766 }); 767 768_LIBCPP_VARIANT_DESTRUCTOR( 769 _Trait::_Unavailable, 770 ~__destructor() = delete;, 771 void __destroy() noexcept = delete;); 772 773#undef _LIBCPP_VARIANT_DESTRUCTOR 774 775template <class _Traits> 776class _LIBCPP_TEMPLATE_VIS __constructor : public __destructor<_Traits> { 777 using __base_type = __destructor<_Traits>; 778 779public: 780 using __base_type::__base_type; 781 using __base_type::operator=; 782 783protected: 784 template <size_t _Ip, class _Tp, class... _Args> 785 inline _LIBCPP_INLINE_VISIBILITY 786 static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) { 787 ::new ((void*)_VSTD::addressof(__a)) 788 __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...); 789 return __a.__value; 790 } 791 792 template <class _Rhs> 793 inline _LIBCPP_INLINE_VISIBILITY 794 static void __generic_construct(__constructor& __lhs, _Rhs&& __rhs) { 795 __lhs.__destroy(); 796 if (!__rhs.valueless_by_exception()) { 797 __visitation::__base::__visit_alt_at( 798 __rhs.index(), 799 [](auto& __lhs_alt, auto&& __rhs_alt) { 800 __construct_alt( 801 __lhs_alt, 802 _VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value); 803 }, 804 __lhs, _VSTD::forward<_Rhs>(__rhs)); 805 __lhs.__index = __rhs.index(); 806 } 807 } 808}; 809 810template <class _Traits, _Trait = _Traits::__move_constructible_trait> 811class _LIBCPP_TEMPLATE_VIS __move_constructor; 812 813#define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, \ 814 move_constructor) \ 815 template <class... _Types> \ 816 class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>, \ 817 move_constructible_trait> \ 818 : public __constructor<__traits<_Types...>> { \ 819 using __base_type = __constructor<__traits<_Types...>>; \ 820 \ 821 public: \ 822 using __base_type::__base_type; \ 823 using __base_type::operator=; \ 824 \ 825 __move_constructor(const __move_constructor&) = default; \ 826 move_constructor \ 827 ~__move_constructor() = default; \ 828 __move_constructor& operator=(const __move_constructor&) = default; \ 829 __move_constructor& operator=(__move_constructor&&) = default; \ 830 } 831 832_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 833 _Trait::_TriviallyAvailable, 834 __move_constructor(__move_constructor&& __that) = default;); 835 836_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 837 _Trait::_Available, 838 __move_constructor(__move_constructor&& __that) noexcept( 839 __all<is_nothrow_move_constructible_v<_Types>...>::value) 840 : __move_constructor(__valueless_t{}) { 841 this->__generic_construct(*this, _VSTD::move(__that)); 842 }); 843 844_LIBCPP_VARIANT_MOVE_CONSTRUCTOR( 845 _Trait::_Unavailable, 846 __move_constructor(__move_constructor&&) = delete;); 847 848#undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR 849 850template <class _Traits, _Trait = _Traits::__copy_constructible_trait> 851class _LIBCPP_TEMPLATE_VIS __copy_constructor; 852 853#define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, \ 854 copy_constructor) \ 855 template <class... _Types> \ 856 class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \ 857 copy_constructible_trait> \ 858 : public __move_constructor<__traits<_Types...>> { \ 859 using __base_type = __move_constructor<__traits<_Types...>>; \ 860 \ 861 public: \ 862 using __base_type::__base_type; \ 863 using __base_type::operator=; \ 864 \ 865 copy_constructor \ 866 __copy_constructor(__copy_constructor&&) = default; \ 867 ~__copy_constructor() = default; \ 868 __copy_constructor& operator=(const __copy_constructor&) = default; \ 869 __copy_constructor& operator=(__copy_constructor&&) = default; \ 870 } 871 872_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 873 _Trait::_TriviallyAvailable, 874 __copy_constructor(const __copy_constructor& __that) = default;); 875 876_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 877 _Trait::_Available, 878 __copy_constructor(const __copy_constructor& __that) 879 : __copy_constructor(__valueless_t{}) { 880 this->__generic_construct(*this, __that); 881 }); 882 883_LIBCPP_VARIANT_COPY_CONSTRUCTOR( 884 _Trait::_Unavailable, 885 __copy_constructor(const __copy_constructor&) = delete;); 886 887#undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR 888 889template <class _Traits> 890class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> { 891 using __base_type = __copy_constructor<_Traits>; 892 893public: 894 using __base_type::__base_type; 895 using __base_type::operator=; 896 897 template <size_t _Ip, class... _Args> 898 inline _LIBCPP_INLINE_VISIBILITY 899 auto& __emplace(_Args&&... __args) { 900 this->__destroy(); 901 auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this), 902 _VSTD::forward<_Args>(__args)...); 903 this->__index = _Ip; 904 return __res; 905 } 906 907protected: 908 template <size_t _Ip, class _Tp, class _Arg> 909 inline _LIBCPP_INLINE_VISIBILITY 910 void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) { 911 if (this->index() == _Ip) { 912 __a.__value = _VSTD::forward<_Arg>(__arg); 913 } else { 914 struct { 915 void operator()(true_type) const { 916 __this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg)); 917 } 918 void operator()(false_type) const { 919 __this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg))); 920 } 921 __assignment* __this; 922 _Arg&& __arg; 923 } __impl{this, _VSTD::forward<_Arg>(__arg)}; 924 __impl(bool_constant<is_nothrow_constructible_v<_Tp, _Arg> || 925 !is_nothrow_move_constructible_v<_Tp>>{}); 926 } 927 } 928 929 template <class _That> 930 inline _LIBCPP_INLINE_VISIBILITY 931 void __generic_assign(_That&& __that) { 932 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 933 // do nothing. 934 } else if (__that.valueless_by_exception()) { 935 this->__destroy(); 936 } else { 937 __visitation::__base::__visit_alt_at( 938 __that.index(), 939 [this](auto& __this_alt, auto&& __that_alt) { 940 this->__assign_alt( 941 __this_alt, 942 _VSTD::forward<decltype(__that_alt)>(__that_alt).__value); 943 }, 944 *this, _VSTD::forward<_That>(__that)); 945 } 946 } 947}; 948 949template <class _Traits, _Trait = _Traits::__move_assignable_trait> 950class _LIBCPP_TEMPLATE_VIS __move_assignment; 951 952#define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, \ 953 move_assignment) \ 954 template <class... _Types> \ 955 class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \ 956 move_assignable_trait> \ 957 : public __assignment<__traits<_Types...>> { \ 958 using __base_type = __assignment<__traits<_Types...>>; \ 959 \ 960 public: \ 961 using __base_type::__base_type; \ 962 using __base_type::operator=; \ 963 \ 964 __move_assignment(const __move_assignment&) = default; \ 965 __move_assignment(__move_assignment&&) = default; \ 966 ~__move_assignment() = default; \ 967 __move_assignment& operator=(const __move_assignment&) = default; \ 968 move_assignment \ 969 } 970 971_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 972 _Trait::_TriviallyAvailable, 973 __move_assignment& operator=(__move_assignment&& __that) = default;); 974 975_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 976 _Trait::_Available, 977 __move_assignment& operator=(__move_assignment&& __that) noexcept( 978 __all<(is_nothrow_move_constructible_v<_Types> && 979 is_nothrow_move_assignable_v<_Types>)...>::value) { 980 this->__generic_assign(_VSTD::move(__that)); 981 return *this; 982 }); 983 984_LIBCPP_VARIANT_MOVE_ASSIGNMENT( 985 _Trait::_Unavailable, 986 __move_assignment& operator=(__move_assignment&&) = delete;); 987 988#undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT 989 990template <class _Traits, _Trait = _Traits::__copy_assignable_trait> 991class _LIBCPP_TEMPLATE_VIS __copy_assignment; 992 993#define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, \ 994 copy_assignment) \ 995 template <class... _Types> \ 996 class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \ 997 copy_assignable_trait> \ 998 : public __move_assignment<__traits<_Types...>> { \ 999 using __base_type = __move_assignment<__traits<_Types...>>; \ 1000 \ 1001 public: \ 1002 using __base_type::__base_type; \ 1003 using __base_type::operator=; \ 1004 \ 1005 __copy_assignment(const __copy_assignment&) = default; \ 1006 __copy_assignment(__copy_assignment&&) = default; \ 1007 ~__copy_assignment() = default; \ 1008 copy_assignment \ 1009 __copy_assignment& operator=(__copy_assignment&&) = default; \ 1010 } 1011 1012_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1013 _Trait::_TriviallyAvailable, 1014 __copy_assignment& operator=(const __copy_assignment& __that) = default;); 1015 1016_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1017 _Trait::_Available, 1018 __copy_assignment& operator=(const __copy_assignment& __that) { 1019 this->__generic_assign(__that); 1020 return *this; 1021 }); 1022 1023_LIBCPP_VARIANT_COPY_ASSIGNMENT( 1024 _Trait::_Unavailable, 1025 __copy_assignment& operator=(const __copy_assignment&) = delete;); 1026 1027#undef _LIBCPP_VARIANT_COPY_ASSIGNMENT 1028 1029template <class... _Types> 1030class _LIBCPP_TEMPLATE_VIS __impl 1031 : public __copy_assignment<__traits<_Types...>> { 1032 using __base_type = __copy_assignment<__traits<_Types...>>; 1033 1034public: 1035 using __base_type::__base_type; 1036 using __base_type::operator=; 1037 1038 template <size_t _Ip, class _Arg> 1039 inline _LIBCPP_INLINE_VISIBILITY 1040 void __assign(_Arg&& __arg) { 1041 this->__assign_alt(__access::__base::__get_alt<_Ip>(*this), 1042 _VSTD::forward<_Arg>(__arg)); 1043 } 1044 1045 inline _LIBCPP_INLINE_VISIBILITY 1046 void __swap(__impl& __that) { 1047 if (this->valueless_by_exception() && __that.valueless_by_exception()) { 1048 // do nothing. 1049 } else if (this->index() == __that.index()) { 1050 __visitation::__base::__visit_alt_at( 1051 this->index(), 1052 [](auto& __this_alt, auto& __that_alt) { 1053 using _VSTD::swap; 1054 swap(__this_alt.__value, __that_alt.__value); 1055 }, 1056 *this, 1057 __that); 1058 } else { 1059 __impl* __lhs = this; 1060 __impl* __rhs = _VSTD::addressof(__that); 1061 if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) { 1062 _VSTD::swap(__lhs, __rhs); 1063 } 1064 __impl __tmp(_VSTD::move(*__rhs)); 1065#ifndef _LIBCPP_NO_EXCEPTIONS 1066 if constexpr (__all<is_nothrow_move_constructible_v<_Types>...>::value) { 1067 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1068 } else { 1069 // EXTENSION: When the move construction of `__lhs` into `__rhs` throws 1070 // and `__tmp` is nothrow move constructible then we move `__tmp` back 1071 // into `__rhs` and provide the strong exception safety guarantee. 1072 try { 1073 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1074 } catch (...) { 1075 if (__tmp.__move_nothrow()) { 1076 this->__generic_construct(*__rhs, _VSTD::move(__tmp)); 1077 } 1078 throw; 1079 } 1080 } 1081#else 1082 // this isn't consolidated with the `if constexpr` branch above due to 1083 // `throw` being ill-formed with exceptions disabled even when discarded. 1084 this->__generic_construct(*__rhs, _VSTD::move(*__lhs)); 1085#endif 1086 this->__generic_construct(*__lhs, _VSTD::move(__tmp)); 1087 } 1088 } 1089 1090private: 1091 inline _LIBCPP_INLINE_VISIBILITY 1092 bool __move_nothrow() const { 1093 constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...}; 1094 return this->valueless_by_exception() || __results[this->index()]; 1095 } 1096}; 1097 1098struct __no_narrowing_check { 1099 template <class _Dest, class _Source> 1100 using _Apply = __identity<_Dest>; 1101}; 1102 1103struct __narrowing_check { 1104 template <class _Dest> 1105 static auto __test_impl(_Dest (&&)[1]) -> __identity<_Dest>; 1106 template <class _Dest, class _Source> 1107 using _Apply _LIBCPP_NODEBUG_TYPE = decltype(__test_impl<_Dest>({std::declval<_Source>()})); 1108}; 1109 1110template <class _Dest, class _Source> 1111using __check_for_narrowing _LIBCPP_NODEBUG_TYPE = 1112 typename _If< 1113#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT 1114 false && 1115#endif 1116 is_arithmetic<_Dest>::value, 1117 __narrowing_check, 1118 __no_narrowing_check 1119 >::template _Apply<_Dest, _Source>; 1120 1121template <class _Tp, size_t _Idx> 1122struct __overload { 1123 template <class _Up> 1124 auto operator()(_Tp, _Up&&) const -> __check_for_narrowing<_Tp, _Up>; 1125}; 1126 1127template <class _Tp, size_t> 1128struct __overload_bool { 1129 template <class _Up, class _Ap = __uncvref_t<_Up>> 1130 auto operator()(bool, _Up&&) const 1131 -> enable_if_t<is_same_v<_Ap, bool>, __identity<_Tp>>; 1132}; 1133 1134template <size_t _Idx> 1135struct __overload<bool, _Idx> : __overload_bool<bool, _Idx> {}; 1136template <size_t _Idx> 1137struct __overload<bool const, _Idx> : __overload_bool<bool const, _Idx> {}; 1138template <size_t _Idx> 1139struct __overload<bool volatile, _Idx> : __overload_bool<bool volatile, _Idx> {}; 1140template <size_t _Idx> 1141struct __overload<bool const volatile, _Idx> : __overload_bool<bool const volatile, _Idx> {}; 1142 1143template <class ..._Bases> 1144struct __all_overloads : _Bases... { 1145 void operator()() const; 1146 using _Bases::operator()...; 1147}; 1148 1149template <class IdxSeq> 1150struct __make_overloads_imp; 1151 1152template <size_t ..._Idx> 1153struct __make_overloads_imp<__tuple_indices<_Idx...> > { 1154 template <class ..._Types> 1155 using _Apply _LIBCPP_NODEBUG_TYPE = __all_overloads<__overload<_Types, _Idx>...>; 1156}; 1157 1158template <class ..._Types> 1159using _MakeOverloads _LIBCPP_NODEBUG_TYPE = typename __make_overloads_imp< 1160 __make_indices_imp<sizeof...(_Types), 0> >::template _Apply<_Types...>; 1161 1162template <class _Tp, class... _Types> 1163using __best_match_t = 1164 typename invoke_result_t<_MakeOverloads<_Types...>, _Tp, _Tp>::type; 1165 1166} // __variant_detail 1167 1168template <class... _Types> 1169class _LIBCPP_TEMPLATE_VIS variant 1170 : private __sfinae_ctor_base< 1171 __all<is_copy_constructible_v<_Types>...>::value, 1172 __all<is_move_constructible_v<_Types>...>::value>, 1173 private __sfinae_assign_base< 1174 __all<(is_copy_constructible_v<_Types> && 1175 is_copy_assignable_v<_Types>)...>::value, 1176 __all<(is_move_constructible_v<_Types> && 1177 is_move_assignable_v<_Types>)...>::value> { 1178 static_assert(0 < sizeof...(_Types), 1179 "variant must consist of at least one alternative."); 1180 1181 static_assert(__all<!is_array_v<_Types>...>::value, 1182 "variant can not have an array type as an alternative."); 1183 1184 static_assert(__all<!is_reference_v<_Types>...>::value, 1185 "variant can not have a reference type as an alternative."); 1186 1187 static_assert(__all<!is_void_v<_Types>...>::value, 1188 "variant can not have a void type as an alternative."); 1189 1190 using __first_type = variant_alternative_t<0, variant>; 1191 1192public: 1193 template <bool _Dummy = true, 1194 enable_if_t<__dependent_type<is_default_constructible<__first_type>, 1195 _Dummy>::value, 1196 int> = 0> 1197 inline _LIBCPP_INLINE_VISIBILITY 1198 constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>) 1199 : __impl(in_place_index<0>) {} 1200 1201 variant(const variant&) = default; 1202 variant(variant&&) = default; 1203 1204 template < 1205 class _Arg, 1206 enable_if_t<!is_same_v<__uncvref_t<_Arg>, variant>, int> = 0, 1207 enable_if_t<!__is_inplace_type<__uncvref_t<_Arg>>::value, int> = 0, 1208 enable_if_t<!__is_inplace_index<__uncvref_t<_Arg>>::value, int> = 0, 1209 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1210 size_t _Ip = 1211 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1212 enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0> 1213 inline _LIBCPP_INLINE_VISIBILITY 1214 constexpr variant(_Arg&& __arg) noexcept( 1215 is_nothrow_constructible_v<_Tp, _Arg>) 1216 : __impl(in_place_index<_Ip>, _VSTD::forward<_Arg>(__arg)) {} 1217 1218 template <size_t _Ip, class... _Args, 1219 class = enable_if_t<(_Ip < sizeof...(_Types)), int>, 1220 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1221 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1222 inline _LIBCPP_INLINE_VISIBILITY 1223 explicit constexpr variant( 1224 in_place_index_t<_Ip>, 1225 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>) 1226 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {} 1227 1228 template < 1229 size_t _Ip, 1230 class _Up, 1231 class... _Args, 1232 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1233 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1234 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1235 int> = 0> 1236 inline _LIBCPP_INLINE_VISIBILITY 1237 explicit constexpr variant( 1238 in_place_index_t<_Ip>, 1239 initializer_list<_Up> __il, 1240 _Args&&... __args) noexcept( 1241 is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>) 1242 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {} 1243 1244 template < 1245 class _Tp, 1246 class... _Args, 1247 size_t _Ip = 1248 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1249 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1250 inline _LIBCPP_INLINE_VISIBILITY 1251 explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept( 1252 is_nothrow_constructible_v<_Tp, _Args...>) 1253 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {} 1254 1255 template < 1256 class _Tp, 1257 class _Up, 1258 class... _Args, 1259 size_t _Ip = 1260 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1261 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1262 int> = 0> 1263 inline _LIBCPP_INLINE_VISIBILITY 1264 explicit constexpr variant( 1265 in_place_type_t<_Tp>, 1266 initializer_list<_Up> __il, 1267 _Args&&... __args) noexcept( 1268 is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>) 1269 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {} 1270 1271 ~variant() = default; 1272 1273 variant& operator=(const variant&) = default; 1274 variant& operator=(variant&&) = default; 1275 1276 template < 1277 class _Arg, 1278 enable_if_t<!is_same_v<__uncvref_t<_Arg>, variant>, int> = 0, 1279 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>, 1280 size_t _Ip = 1281 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1282 enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>, 1283 int> = 0> 1284 inline _LIBCPP_INLINE_VISIBILITY 1285 variant& operator=(_Arg&& __arg) noexcept( 1286 is_nothrow_assignable_v<_Tp&, _Arg> && 1287 is_nothrow_constructible_v<_Tp, _Arg>) { 1288 __impl.template __assign<_Ip>(_VSTD::forward<_Arg>(__arg)); 1289 return *this; 1290 } 1291 1292 template < 1293 size_t _Ip, 1294 class... _Args, 1295 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1296 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1297 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1298 inline _LIBCPP_INLINE_VISIBILITY 1299 _Tp& emplace(_Args&&... __args) { 1300 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); 1301 } 1302 1303 template < 1304 size_t _Ip, 1305 class _Up, 1306 class... _Args, 1307 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0, 1308 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>, 1309 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1310 int> = 0> 1311 inline _LIBCPP_INLINE_VISIBILITY 1312 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1313 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); 1314 } 1315 1316 template < 1317 class _Tp, 1318 class... _Args, 1319 size_t _Ip = 1320 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1321 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0> 1322 inline _LIBCPP_INLINE_VISIBILITY 1323 _Tp& emplace(_Args&&... __args) { 1324 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...); 1325 } 1326 1327 template < 1328 class _Tp, 1329 class _Up, 1330 class... _Args, 1331 size_t _Ip = 1332 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value, 1333 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, 1334 int> = 0> 1335 inline _LIBCPP_INLINE_VISIBILITY 1336 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) { 1337 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...); 1338 } 1339 1340 inline _LIBCPP_INLINE_VISIBILITY 1341 constexpr bool valueless_by_exception() const noexcept { 1342 return __impl.valueless_by_exception(); 1343 } 1344 1345 inline _LIBCPP_INLINE_VISIBILITY 1346 constexpr size_t index() const noexcept { return __impl.index(); } 1347 1348 template < 1349 bool _Dummy = true, 1350 enable_if_t< 1351 __all<( 1352 __dependent_type<is_move_constructible<_Types>, _Dummy>::value && 1353 __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value, 1354 int> = 0> 1355 inline _LIBCPP_INLINE_VISIBILITY 1356 void swap(variant& __that) noexcept( 1357 __all<(is_nothrow_move_constructible_v<_Types> && 1358 is_nothrow_swappable_v<_Types>)...>::value) { 1359 __impl.__swap(__that.__impl); 1360 } 1361 1362private: 1363 __variant_detail::__impl<_Types...> __impl; 1364 1365 friend struct __variant_detail::__access::__variant; 1366 friend struct __variant_detail::__visitation::__variant; 1367}; 1368 1369template <size_t _Ip, class... _Types> 1370inline _LIBCPP_INLINE_VISIBILITY 1371constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept { 1372 return __v.index() == _Ip; 1373} 1374 1375template <class _Tp, class... _Types> 1376inline _LIBCPP_INLINE_VISIBILITY 1377constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept { 1378 return __holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1379} 1380 1381template <size_t _Ip, class _Vp> 1382inline _LIBCPP_INLINE_VISIBILITY 1383_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1384constexpr auto&& __generic_get(_Vp&& __v) { 1385 using __variant_detail::__access::__variant; 1386 if (!__holds_alternative<_Ip>(__v)) { 1387 __throw_bad_variant_access(); 1388 } 1389 return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value; 1390} 1391 1392template <size_t _Ip, class... _Types> 1393inline _LIBCPP_INLINE_VISIBILITY 1394_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1395constexpr variant_alternative_t<_Ip, variant<_Types...>>& get( 1396 variant<_Types...>& __v) { 1397 static_assert(_Ip < sizeof...(_Types)); 1398 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1399 return __generic_get<_Ip>(__v); 1400} 1401 1402template <size_t _Ip, class... _Types> 1403inline _LIBCPP_INLINE_VISIBILITY 1404_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1405constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get( 1406 variant<_Types...>&& __v) { 1407 static_assert(_Ip < sizeof...(_Types)); 1408 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1409 return __generic_get<_Ip>(_VSTD::move(__v)); 1410} 1411 1412template <size_t _Ip, class... _Types> 1413inline _LIBCPP_INLINE_VISIBILITY 1414_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1415constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get( 1416 const variant<_Types...>& __v) { 1417 static_assert(_Ip < sizeof...(_Types)); 1418 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1419 return __generic_get<_Ip>(__v); 1420} 1421 1422template <size_t _Ip, class... _Types> 1423inline _LIBCPP_INLINE_VISIBILITY 1424_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1425constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get( 1426 const variant<_Types...>&& __v) { 1427 static_assert(_Ip < sizeof...(_Types)); 1428 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1429 return __generic_get<_Ip>(_VSTD::move(__v)); 1430} 1431 1432template <class _Tp, class... _Types> 1433inline _LIBCPP_INLINE_VISIBILITY 1434_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1435constexpr _Tp& get(variant<_Types...>& __v) { 1436 static_assert(!is_void_v<_Tp>); 1437 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1438} 1439 1440template <class _Tp, class... _Types> 1441inline _LIBCPP_INLINE_VISIBILITY 1442_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1443constexpr _Tp&& get(variant<_Types...>&& __v) { 1444 static_assert(!is_void_v<_Tp>); 1445 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1446 _VSTD::move(__v)); 1447} 1448 1449template <class _Tp, class... _Types> 1450inline _LIBCPP_INLINE_VISIBILITY 1451_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1452constexpr const _Tp& get(const variant<_Types...>& __v) { 1453 static_assert(!is_void_v<_Tp>); 1454 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1455} 1456 1457template <class _Tp, class... _Types> 1458inline _LIBCPP_INLINE_VISIBILITY 1459_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1460constexpr const _Tp&& get(const variant<_Types...>&& __v) { 1461 static_assert(!is_void_v<_Tp>); 1462 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>( 1463 _VSTD::move(__v)); 1464} 1465 1466template <size_t _Ip, class _Vp> 1467inline _LIBCPP_INLINE_VISIBILITY 1468constexpr auto* __generic_get_if(_Vp* __v) noexcept { 1469 using __variant_detail::__access::__variant; 1470 return __v && __holds_alternative<_Ip>(*__v) 1471 ? _VSTD::addressof(__variant::__get_alt<_Ip>(*__v).__value) 1472 : nullptr; 1473} 1474 1475template <size_t _Ip, class... _Types> 1476inline _LIBCPP_INLINE_VISIBILITY 1477constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>> 1478get_if(variant<_Types...>* __v) noexcept { 1479 static_assert(_Ip < sizeof...(_Types)); 1480 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1481 return __generic_get_if<_Ip>(__v); 1482} 1483 1484template <size_t _Ip, class... _Types> 1485inline _LIBCPP_INLINE_VISIBILITY 1486constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>> 1487get_if(const variant<_Types...>* __v) noexcept { 1488 static_assert(_Ip < sizeof...(_Types)); 1489 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>); 1490 return __generic_get_if<_Ip>(__v); 1491} 1492 1493template <class _Tp, class... _Types> 1494inline _LIBCPP_INLINE_VISIBILITY 1495constexpr add_pointer_t<_Tp> 1496get_if(variant<_Types...>* __v) noexcept { 1497 static_assert(!is_void_v<_Tp>); 1498 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1499} 1500 1501template <class _Tp, class... _Types> 1502inline _LIBCPP_INLINE_VISIBILITY 1503constexpr add_pointer_t<const _Tp> 1504get_if(const variant<_Types...>* __v) noexcept { 1505 static_assert(!is_void_v<_Tp>); 1506 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v); 1507} 1508 1509template <class _Operator> 1510struct __convert_to_bool { 1511 template <class _T1, class _T2> 1512 _LIBCPP_INLINE_VISIBILITY constexpr bool operator()(_T1 && __t1, _T2&& __t2) const { 1513 static_assert(std::is_convertible<decltype(_Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2))), bool>::value, 1514 "the relational operator does not return a type which is implicitly convertible to bool"); 1515 return _Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2)); 1516 } 1517}; 1518 1519template <class... _Types> 1520inline _LIBCPP_INLINE_VISIBILITY 1521constexpr bool operator==(const variant<_Types...>& __lhs, 1522 const variant<_Types...>& __rhs) { 1523 using __variant_detail::__visitation::__variant; 1524 if (__lhs.index() != __rhs.index()) return false; 1525 if (__lhs.valueless_by_exception()) return true; 1526 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<equal_to<>>{}, __lhs, __rhs); 1527} 1528 1529template <class... _Types> 1530inline _LIBCPP_INLINE_VISIBILITY 1531constexpr bool operator!=(const variant<_Types...>& __lhs, 1532 const variant<_Types...>& __rhs) { 1533 using __variant_detail::__visitation::__variant; 1534 if (__lhs.index() != __rhs.index()) return true; 1535 if (__lhs.valueless_by_exception()) return false; 1536 return __variant::__visit_value_at( 1537 __lhs.index(), __convert_to_bool<not_equal_to<>>{}, __lhs, __rhs); 1538} 1539 1540template <class... _Types> 1541inline _LIBCPP_INLINE_VISIBILITY 1542constexpr bool operator<(const variant<_Types...>& __lhs, 1543 const variant<_Types...>& __rhs) { 1544 using __variant_detail::__visitation::__variant; 1545 if (__rhs.valueless_by_exception()) return false; 1546 if (__lhs.valueless_by_exception()) return true; 1547 if (__lhs.index() < __rhs.index()) return true; 1548 if (__lhs.index() > __rhs.index()) return false; 1549 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<less<>>{}, __lhs, __rhs); 1550} 1551 1552template <class... _Types> 1553inline _LIBCPP_INLINE_VISIBILITY 1554constexpr bool operator>(const variant<_Types...>& __lhs, 1555 const variant<_Types...>& __rhs) { 1556 using __variant_detail::__visitation::__variant; 1557 if (__lhs.valueless_by_exception()) return false; 1558 if (__rhs.valueless_by_exception()) return true; 1559 if (__lhs.index() > __rhs.index()) return true; 1560 if (__lhs.index() < __rhs.index()) return false; 1561 return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<greater<>>{}, __lhs, __rhs); 1562} 1563 1564template <class... _Types> 1565inline _LIBCPP_INLINE_VISIBILITY 1566constexpr bool operator<=(const variant<_Types...>& __lhs, 1567 const variant<_Types...>& __rhs) { 1568 using __variant_detail::__visitation::__variant; 1569 if (__lhs.valueless_by_exception()) return true; 1570 if (__rhs.valueless_by_exception()) return false; 1571 if (__lhs.index() < __rhs.index()) return true; 1572 if (__lhs.index() > __rhs.index()) return false; 1573 return __variant::__visit_value_at( 1574 __lhs.index(), __convert_to_bool<less_equal<>>{}, __lhs, __rhs); 1575} 1576 1577template <class... _Types> 1578inline _LIBCPP_INLINE_VISIBILITY 1579constexpr bool operator>=(const variant<_Types...>& __lhs, 1580 const variant<_Types...>& __rhs) { 1581 using __variant_detail::__visitation::__variant; 1582 if (__rhs.valueless_by_exception()) return true; 1583 if (__lhs.valueless_by_exception()) return false; 1584 if (__lhs.index() > __rhs.index()) return true; 1585 if (__lhs.index() < __rhs.index()) return false; 1586 return __variant::__visit_value_at( 1587 __lhs.index(), __convert_to_bool<greater_equal<>>{}, __lhs, __rhs); 1588} 1589 1590template <class _Visitor, class... _Vs> 1591inline _LIBCPP_INLINE_VISIBILITY 1592_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS 1593constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) { 1594 using __variant_detail::__visitation::__variant; 1595 bool __results[] = {__vs.valueless_by_exception()...}; 1596 for (bool __result : __results) { 1597 if (__result) { 1598 __throw_bad_variant_access(); 1599 } 1600 } 1601 return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor), 1602 _VSTD::forward<_Vs>(__vs)...); 1603} 1604 1605struct _LIBCPP_TEMPLATE_VIS monostate {}; 1606 1607inline _LIBCPP_INLINE_VISIBILITY 1608constexpr bool operator<(monostate, monostate) noexcept { return false; } 1609 1610inline _LIBCPP_INLINE_VISIBILITY 1611constexpr bool operator>(monostate, monostate) noexcept { return false; } 1612 1613inline _LIBCPP_INLINE_VISIBILITY 1614constexpr bool operator<=(monostate, monostate) noexcept { return true; } 1615 1616inline _LIBCPP_INLINE_VISIBILITY 1617constexpr bool operator>=(monostate, monostate) noexcept { return true; } 1618 1619inline _LIBCPP_INLINE_VISIBILITY 1620constexpr bool operator==(monostate, monostate) noexcept { return true; } 1621 1622inline _LIBCPP_INLINE_VISIBILITY 1623constexpr bool operator!=(monostate, monostate) noexcept { return false; } 1624 1625template <class... _Types> 1626inline _LIBCPP_INLINE_VISIBILITY 1627auto swap(variant<_Types...>& __lhs, 1628 variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs))) 1629 -> decltype(__lhs.swap(__rhs)) { 1630 __lhs.swap(__rhs); 1631} 1632 1633template <class... _Types> 1634struct _LIBCPP_TEMPLATE_VIS hash< 1635 __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> { 1636 using argument_type = variant<_Types...>; 1637 using result_type = size_t; 1638 1639 inline _LIBCPP_INLINE_VISIBILITY 1640 result_type operator()(const argument_type& __v) const { 1641 using __variant_detail::__visitation::__variant; 1642 size_t __res = 1643 __v.valueless_by_exception() 1644 ? 299792458 // Random value chosen by the universe upon creation 1645 : __variant::__visit_alt( 1646 [](const auto& __alt) { 1647 using __alt_type = __uncvref_t<decltype(__alt)>; 1648 using __value_type = remove_const_t< 1649 typename __alt_type::__value_type>; 1650 return hash<__value_type>{}(__alt.__value); 1651 }, 1652 __v); 1653 return __hash_combine(__res, hash<size_t>{}(__v.index())); 1654 } 1655}; 1656 1657template <> 1658struct _LIBCPP_TEMPLATE_VIS hash<monostate> { 1659 using argument_type = monostate; 1660 using result_type = size_t; 1661 1662 inline _LIBCPP_INLINE_VISIBILITY 1663 result_type operator()(const argument_type&) const _NOEXCEPT { 1664 return 66740831; // return a fundamentally attractive random value. 1665 } 1666}; 1667 1668#endif // _LIBCPP_STD_VER > 14 1669 1670_LIBCPP_END_NAMESPACE_STD 1671 1672_LIBCPP_POP_MACROS 1673 1674#endif // _LIBCPP_VARIANT 1675