2 //===------------------------------ variant -------------------------------===//
4 // The LLVM Compiler Infrastructure
6 // This file is dual licensed under the MIT and the University of Illinois Open
7 // Source Licenses. See LICENSE.TXT for details.
9 //===----------------------------------------------------------------------===//
11 #ifndef _LIBCPP_VARIANT
12 #define _LIBCPP_VARIANT
19 // 20.7.2, class template variant
20 template <class... Types>
24 // 20.7.2.1, constructors
25 constexpr variant() noexcept(see below);
26 variant(const variant&);
27 variant(variant&&) noexcept(see below);
29 template <class T> constexpr variant(T&&) noexcept(see below);
31 template <class T, class... Args>
32 constexpr explicit variant(in_place_type_t<T>, Args&&...);
34 template <class T, class U, class... Args>
35 constexpr explicit variant(
36 in_place_type_t<T>, initializer_list<U>, Args&&...);
38 template <size_t I, class... Args>
39 constexpr explicit variant(in_place_index_t<I>, Args&&...);
41 template <size_t I, class U, class... Args>
42 constexpr explicit variant(
43 in_place_index_t<I>, initializer_list<U>, Args&&...);
45 // 20.7.2.2, destructor
48 // 20.7.2.3, assignment
49 variant& operator=(const variant&);
50 variant& operator=(variant&&) noexcept(see below);
52 template <class T> variant& operator=(T&&) noexcept(see below);
54 // 20.7.2.4, modifiers
55 template <class T, class... Args>
56 void emplace(Args&&...);
58 template <class T, class U, class... Args>
59 void emplace(initializer_list<U>, Args&&...);
61 template <size_t I, class... Args>
62 void emplace(Args&&...);
64 template <size_t I, class U, class... Args>
65 void emplace(initializer_list<U>, Args&&...);
67 // 20.7.2.5, value status
68 constexpr bool valueless_by_exception() const noexcept;
69 constexpr size_t index() const noexcept;
72 void swap(variant&) noexcept(see below);
75 // 20.7.3, variant helper classes
76 template <class T> struct variant_size; // undefined
79 constexpr size_t variant_size_v = variant_size<T>::value;
81 template <class T> struct variant_size<const T>;
82 template <class T> struct variant_size<volatile T>;
83 template <class T> struct variant_size<const volatile T>;
85 template <class... Types>
86 struct variant_size<variant<Types...>>;
88 template <size_t I, class T> struct variant_alternative; // undefined
90 template <size_t I, class T>
91 using variant_alternative_t = typename variant_alternative<I, T>::type;
93 template <size_t I, class T> struct variant_alternative<I, const T>;
94 template <size_t I, class T> struct variant_alternative<I, volatile T>;
95 template <size_t I, class T> struct variant_alternative<I, const volatile T>;
97 template <size_t I, class... Types>
98 struct variant_alternative<I, variant<Types...>>;
100 constexpr size_t variant_npos = -1;
102 // 20.7.4, value access
103 template <class T, class... Types>
104 constexpr bool holds_alternative(const variant<Types...>&) noexcept;
106 template <size_t I, class... Types>
107 constexpr variant_alternative_t<I, variant<Types...>>&
108 get(variant<Types...>&);
110 template <size_t I, class... Types>
111 constexpr variant_alternative_t<I, variant<Types...>>&&
112 get(variant<Types...>&&);
114 template <size_t I, class... Types>
115 constexpr variant_alternative_t<I, variant<Types...>> const&
116 get(const variant<Types...>&);
118 template <size_t I, class... Types>
119 constexpr variant_alternative_t<I, variant<Types...>> const&&
120 get(const variant<Types...>&&);
122 template <class T, class... Types>
123 constexpr T& get(variant<Types...>&);
125 template <class T, class... Types>
126 constexpr T&& get(variant<Types...>&&);
128 template <class T, class... Types>
129 constexpr const T& get(const variant<Types...>&);
131 template <class T, class... Types>
132 constexpr const T&& get(const variant<Types...>&&);
134 template <size_t I, class... Types>
135 constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>>
136 get_if(variant<Types...>*) noexcept;
138 template <size_t I, class... Types>
139 constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>>
140 get_if(const variant<Types...>*) noexcept;
142 template <class T, class... Types>
143 constexpr add_pointer_t<T>
144 get_if(variant<Types...>*) noexcept;
146 template <class T, class... Types>
147 constexpr add_pointer_t<const T>
148 get_if(const variant<Types...>*) noexcept;
150 // 20.7.5, relational operators
151 template <class... Types>
152 constexpr bool operator==(const variant<Types...>&, const variant<Types...>&);
154 template <class... Types>
155 constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&);
157 template <class... Types>
158 constexpr bool operator<(const variant<Types...>&, const variant<Types...>&);
160 template <class... Types>
161 constexpr bool operator>(const variant<Types...>&, const variant<Types...>&);
163 template <class... Types>
164 constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&);
166 template <class... Types>
167 constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&);
169 // 20.7.6, visitation
170 template <class Visitor, class... Variants>
171 constexpr see below visit(Visitor&&, Variants&&...);
173 // 20.7.7, class monostate
176 // 20.7.8, monostate relational operators
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 constexpr bool operator!=(monostate, monostate) noexcept;
184 // 20.7.9, specialized algorithms
185 template <class... Types>
186 void swap(variant<Types...>&, variant<Types...>&) noexcept(see below);
188 // 20.7.10, class bad_variant_access
189 class bad_variant_access;
191 // 20.7.11, hash support
192 template <class T> struct hash;
193 template <class... Types> struct hash<variant<Types...>>;
194 template <> struct hash<monostate>;
204 #include <functional>
205 #include <initializer_list>
208 #include <type_traits>
211 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
212 #pragma GCC system_header
215 namespace std { // explicitly not using versioning namespace
217 class _LIBCPP_EXCEPTION_ABI bad_variant_access : public exception {
219 virtual const char* what() const _NOEXCEPT;
224 _LIBCPP_BEGIN_NAMESPACE_STD
226 #if _LIBCPP_STD_VER > 14
229 inline _LIBCPP_INLINE_VISIBILITY
230 void __throw_bad_variant_access() {
231 #ifndef _LIBCPP_NO_EXCEPTIONS
232 throw bad_variant_access();
238 template <class... _Types>
239 class _LIBCPP_TEMPLATE_VIS variant;
242 struct _LIBCPP_TEMPLATE_VIS variant_size;
245 constexpr size_t variant_size_v = variant_size<_Tp>::value;
248 struct _LIBCPP_TEMPLATE_VIS variant_size<const _Tp> : variant_size<_Tp> {};
251 struct _LIBCPP_TEMPLATE_VIS variant_size<volatile _Tp> : variant_size<_Tp> {};
254 struct _LIBCPP_TEMPLATE_VIS variant_size<const volatile _Tp>
255 : variant_size<_Tp> {};
257 template <class... _Types>
258 struct _LIBCPP_TEMPLATE_VIS variant_size<variant<_Types...>>
259 : integral_constant<size_t, sizeof...(_Types)> {};
261 template <size_t _Ip, class _Tp>
262 struct _LIBCPP_TEMPLATE_VIS variant_alternative;
264 template <size_t _Ip, class _Tp>
265 using variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type;
267 template <size_t _Ip, class _Tp>
268 struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const _Tp>
269 : add_const<variant_alternative_t<_Ip, _Tp>> {};
271 template <size_t _Ip, class _Tp>
272 struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, volatile _Tp>
273 : add_volatile<variant_alternative_t<_Ip, _Tp>> {};
275 template <size_t _Ip, class _Tp>
276 struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const volatile _Tp>
277 : add_cv<variant_alternative_t<_Ip, _Tp>> {};
279 template <size_t _Ip, class... _Types>
280 struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, variant<_Types...>> {
281 static_assert(_Ip < sizeof...(_Types));
282 using type = __type_pack_element<_Ip, _Types...>;
285 constexpr size_t variant_npos = static_cast<size_t>(-1);
286 constexpr unsigned int __variant_npos = static_cast<unsigned int>(-1);
288 namespace __find_detail {
290 template <class _Tp, class... _Types>
291 inline _LIBCPP_INLINE_VISIBILITY
292 constexpr size_t __find_index() {
293 constexpr bool __matches[] = {is_same_v<_Tp, _Types>...};
294 size_t __result = __not_found;
295 for (size_t __i = 0; __i < sizeof...(_Types); ++__i) {
296 if (__matches[__i]) {
297 if (__result != __not_found) {
306 template <size_t _Index>
307 struct __find_unambiguous_index_sfinae_impl
308 : integral_constant<size_t, _Index> {};
311 struct __find_unambiguous_index_sfinae_impl<__not_found> {};
314 struct __find_unambiguous_index_sfinae_impl<__ambiguous> {};
316 template <class _Tp, class... _Types>
317 struct __find_unambiguous_index_sfinae
318 : __find_unambiguous_index_sfinae_impl<__find_index<_Tp, _Types...>()> {};
320 } // namespace __find_detail
322 namespace __variant_detail {
324 struct __valueless_t {};
326 enum class _Trait { _TriviallyAvailable, _Available, _Unavailable };
328 template <typename _Tp,
329 template <typename> class _IsTriviallyAvailable,
330 template <typename> class _IsAvailable>
331 constexpr _Trait __trait =
332 _IsTriviallyAvailable<_Tp>::value
333 ? _Trait::_TriviallyAvailable
334 : _IsAvailable<_Tp>::value ? _Trait::_Available : _Trait::_Unavailable;
336 inline _LIBCPP_INLINE_VISIBILITY
337 constexpr _Trait __common_trait(initializer_list<_Trait> __traits) {
338 _Trait __result = _Trait::_TriviallyAvailable;
339 for (_Trait __t : __traits) {
340 if (static_cast<int>(__t) > static_cast<int>(__result)) {
347 template <typename... _Types>
349 static constexpr _Trait __copy_constructible_trait =
350 __common_trait({__trait<_Types,
351 is_trivially_copy_constructible,
352 is_copy_constructible>...});
354 static constexpr _Trait __move_constructible_trait =
355 __common_trait({__trait<_Types,
356 is_trivially_move_constructible,
357 is_move_constructible>...});
359 static constexpr _Trait __copy_assignable_trait = __common_trait(
360 {__copy_constructible_trait,
361 __move_constructible_trait,
362 __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...});
364 static constexpr _Trait __move_assignable_trait = __common_trait(
365 {__move_constructible_trait,
366 __trait<_Types, is_trivially_move_assignable, is_move_assignable>...});
368 static constexpr _Trait __destructible_trait = __common_trait(
369 {__trait<_Types, is_trivially_destructible, is_destructible>...});
376 inline _LIBCPP_INLINE_VISIBILITY
377 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) {
378 return _VSTD::forward<_Vp>(__v).__head;
381 template <class _Vp, size_t _Ip>
382 inline _LIBCPP_INLINE_VISIBILITY
383 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) {
384 return __get_alt(_VSTD::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>);
389 template <size_t _Ip, class _Vp>
390 inline _LIBCPP_INLINE_VISIBILITY
391 static constexpr auto&& __get_alt(_Vp&& __v) {
392 return __union::__get_alt(_VSTD::forward<_Vp>(__v).__data,
393 in_place_index<_Ip>);
398 template <size_t _Ip, class _Vp>
399 inline _LIBCPP_INLINE_VISIBILITY
400 static constexpr auto&& __get_alt(_Vp&& __v) {
401 return __base::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v).__impl);
405 } // namespace __access
407 namespace __visitation {
410 template <class _Visitor, class... _Vs>
411 inline _LIBCPP_INLINE_VISIBILITY
412 static constexpr decltype(auto)
413 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
414 constexpr auto __fdiagonal =
415 __make_fdiagonal<_Visitor&&,
416 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
417 return __fdiagonal[__index](_VSTD::forward<_Visitor>(__visitor),
418 _VSTD::forward<_Vs>(__vs).__as_base()...);
421 template <class _Visitor, class... _Vs>
422 inline _LIBCPP_INLINE_VISIBILITY
423 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
425 constexpr auto __fmatrix =
426 __make_fmatrix<_Visitor&&,
427 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
428 const size_t __indices[] = {__vs.index()...};
429 return __at(__fmatrix, __indices)(_VSTD::forward<_Visitor>(__visitor),
430 _VSTD::forward<_Vs>(__vs).__as_base()...);
435 inline _LIBCPP_INLINE_VISIBILITY
436 static constexpr const _Tp& __at_impl(const _Tp& __elem, const size_t*) {
440 template <class _Tp, size_t _Np>
441 inline _LIBCPP_INLINE_VISIBILITY
442 static constexpr auto&& __at_impl(const array<_Tp, _Np>& __elems,
443 const size_t* __index) {
444 return __at_impl(__elems[*__index], __index + 1);
447 template <class _Tp, size_t _Np, size_t _Ip>
448 inline _LIBCPP_INLINE_VISIBILITY
449 static constexpr auto&& __at(const array<_Tp, _Np>& __elems,
450 const size_t (&__indices)[_Ip]) {
451 return __at_impl(__elems, begin(__indices));
454 template <class _Fp, class... _Fs>
455 static constexpr void __std_visit_visitor_return_type_check() {
457 __all<is_same_v<_Fp, _Fs>...>::value,
458 "`std::visit` requires the visitor to have a single return type.");
461 template <class... _Fs>
462 inline _LIBCPP_INLINE_VISIBILITY
463 static constexpr auto __make_farray(_Fs&&... __fs) {
464 __std_visit_visitor_return_type_check<decay_t<_Fs>...>();
465 using __result = array<common_type_t<decay_t<_Fs>...>, sizeof...(_Fs)>;
466 return __result{{_VSTD::forward<_Fs>(__fs)...}};
469 template <class _Fp, class... _Vs, size_t... _Is>
470 inline _LIBCPP_INLINE_VISIBILITY
471 static constexpr auto __make_dispatch(index_sequence<_Is...>) {
472 struct __dispatcher {
473 static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) {
474 return __invoke_constexpr(
475 static_cast<_Fp>(__f),
476 __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...);
479 return _VSTD::addressof(__dispatcher::__dispatch);
482 template <size_t _Ip, class _Fp, class... _Vs>
483 inline _LIBCPP_INLINE_VISIBILITY
484 static constexpr auto __make_fdiagonal_impl() {
485 return __make_dispatch<_Fp, _Vs...>(
486 index_sequence<(__identity<_Vs>{}, _Ip)...>{});
489 template <class _Fp, class... _Vs, size_t... _Is>
490 inline _LIBCPP_INLINE_VISIBILITY
491 static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) {
492 return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...);
495 template <class _Fp, class _Vp, class... _Vs>
496 inline _LIBCPP_INLINE_VISIBILITY
497 static constexpr auto __make_fdiagonal() {
498 constexpr size_t _Np = decay_t<_Vp>::__size();
499 static_assert(__all<(_Np == decay_t<_Vs>::__size())...>::value);
500 return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<_Np>{});
503 template <class _Fp, class... _Vs, size_t... _Is>
504 inline _LIBCPP_INLINE_VISIBILITY
505 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) {
506 return __make_dispatch<_Fp, _Vs...>(__is);
509 template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls>
510 inline _LIBCPP_INLINE_VISIBILITY
511 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>,
512 index_sequence<_Js...>,
514 return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>(
515 index_sequence<_Is..., _Js>{}, __ls...)...);
518 template <class _Fp, class... _Vs>
519 inline _LIBCPP_INLINE_VISIBILITY
520 static constexpr auto __make_fmatrix() {
521 return __make_fmatrix_impl<_Fp, _Vs...>(
522 index_sequence<>{}, make_index_sequence<decay_t<_Vs>::__size()>{}...);
527 template <class _Visitor, class... _Vs>
528 inline _LIBCPP_INLINE_VISIBILITY
529 static constexpr decltype(auto)
530 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
531 return __base::__visit_alt_at(__index,
532 _VSTD::forward<_Visitor>(__visitor),
533 _VSTD::forward<_Vs>(__vs).__impl...);
536 template <class _Visitor, class... _Vs>
537 inline _LIBCPP_INLINE_VISIBILITY
538 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
540 return __base::__visit_alt(_VSTD::forward<_Visitor>(__visitor),
541 _VSTD::forward<_Vs>(__vs).__impl...);
544 template <class _Visitor, class... _Vs>
545 inline _LIBCPP_INLINE_VISIBILITY
546 static constexpr decltype(auto)
547 __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
548 return __visit_alt_at(
550 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
551 _VSTD::forward<_Vs>(__vs)...);
554 template <class _Visitor, class... _Vs>
555 inline _LIBCPP_INLINE_VISIBILITY
556 static constexpr decltype(auto) __visit_value(_Visitor&& __visitor,
559 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
560 _VSTD::forward<_Vs>(__vs)...);
564 template <class _Visitor, class... _Values>
565 static constexpr void __std_visit_exhaustive_visitor_check() {
566 static_assert(is_callable_v<_Visitor(_Values...)>,
567 "`std::visit` requires the visitor to be exhaustive.");
570 template <class _Visitor>
571 struct __value_visitor {
572 template <class... _Alts>
573 inline _LIBCPP_INLINE_VISIBILITY
574 constexpr decltype(auto) operator()(_Alts&&... __alts) const {
575 __std_visit_exhaustive_visitor_check<
577 decltype((_VSTD::forward<_Alts>(__alts).__value))...>();
578 return __invoke_constexpr(_VSTD::forward<_Visitor>(__visitor),
579 _VSTD::forward<_Alts>(__alts).__value...);
581 _Visitor&& __visitor;
584 template <class _Visitor>
585 inline _LIBCPP_INLINE_VISIBILITY
586 static constexpr auto __make_value_visitor(_Visitor&& __visitor) {
587 return __value_visitor<_Visitor>{_VSTD::forward<_Visitor>(__visitor)};
591 } // namespace __visitation
593 template <size_t _Index, class _Tp>
594 struct _LIBCPP_TEMPLATE_VIS __alt {
595 using __value_type = _Tp;
597 template <class... _Args>
598 inline _LIBCPP_INLINE_VISIBILITY
599 explicit constexpr __alt(in_place_t, _Args&&... __args)
600 : __value(_VSTD::forward<_Args>(__args)...) {}
602 __value_type __value;
605 template <_Trait _DestructibleTrait, size_t _Index, class... _Types>
606 union _LIBCPP_TEMPLATE_VIS __union;
608 template <_Trait _DestructibleTrait, size_t _Index>
609 union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {};
611 #define _LIBCPP_VARIANT_UNION(destructible_trait, destructor) \
612 template <size_t _Index, class _Tp, class... _Types> \
613 union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \
618 inline _LIBCPP_INLINE_VISIBILITY \
619 explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \
621 template <class... _Args> \
622 inline _LIBCPP_INLINE_VISIBILITY \
623 explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \
624 : __head(in_place, _VSTD::forward<_Args>(__args)...) {} \
626 template <size_t _Ip, class... _Args> \
627 inline _LIBCPP_INLINE_VISIBILITY \
628 explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \
629 : __tail(in_place_index<_Ip - 1>, _VSTD::forward<_Args>(__args)...) {} \
631 __union(const __union&) = default; \
632 __union(__union&&) = default; \
636 __union& operator=(const __union&) = default; \
637 __union& operator=(__union&&) = default; \
641 __alt<_Index, _Tp> __head; \
642 __union<destructible_trait, _Index + 1, _Types...> __tail; \
644 friend struct __access::__union; \
647 _LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;);
648 _LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {});
649 _LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;);
651 #undef _LIBCPP_VARIANT_UNION
653 template <_Trait _DestructibleTrait, class... _Types>
654 class _LIBCPP_TEMPLATE_VIS __base {
656 inline _LIBCPP_INLINE_VISIBILITY
657 explicit constexpr __base(__valueless_t tag) noexcept
658 : __data(tag), __index(__variant_npos) {}
660 template <size_t _Ip, class... _Args>
661 inline _LIBCPP_INLINE_VISIBILITY
662 explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args)
664 __data(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...),
667 inline _LIBCPP_INLINE_VISIBILITY
668 constexpr bool valueless_by_exception() const noexcept {
669 return index() == variant_npos;
672 inline _LIBCPP_INLINE_VISIBILITY
673 constexpr size_t index() const noexcept {
674 return __index == __variant_npos ? variant_npos : __index;
678 inline _LIBCPP_INLINE_VISIBILITY
679 constexpr auto&& __as_base() & { return *this; }
681 inline _LIBCPP_INLINE_VISIBILITY
682 constexpr auto&& __as_base() && { return _VSTD::move(*this); }
684 inline _LIBCPP_INLINE_VISIBILITY
685 constexpr auto&& __as_base() const & { return *this; }
687 inline _LIBCPP_INLINE_VISIBILITY
688 constexpr auto&& __as_base() const && { return _VSTD::move(*this); }
690 inline _LIBCPP_INLINE_VISIBILITY
691 static constexpr size_t __size() { return sizeof...(_Types); }
693 __union<_DestructibleTrait, 0, _Types...> __data;
694 unsigned int __index;
696 friend struct __access::__base;
697 friend struct __visitation::__base;
700 template <class _Traits, _Trait = _Traits::__destructible_trait>
701 class _LIBCPP_TEMPLATE_VIS __destructor;
703 #define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy) \
704 template <class... _Types> \
705 class _LIBCPP_TEMPLATE_VIS __destructor<__traits<_Types...>, \
706 destructible_trait> \
707 : public __base<destructible_trait, _Types...> { \
708 using __base_type = __base<destructible_trait, _Types...>; \
711 using __base_type::__base_type; \
712 using __base_type::operator=; \
714 __destructor(const __destructor&) = default; \
715 __destructor(__destructor&&) = default; \
717 __destructor& operator=(const __destructor&) = default; \
718 __destructor& operator=(__destructor&&) = default; \
721 inline _LIBCPP_INLINE_VISIBILITY \
725 _LIBCPP_VARIANT_DESTRUCTOR(
726 _Trait::_TriviallyAvailable,
727 ~__destructor() = default;,
728 void __destroy() noexcept { this->__index = __variant_npos; });
730 _LIBCPP_VARIANT_DESTRUCTOR(
732 ~__destructor() { __destroy(); },
733 void __destroy() noexcept {
734 if (!this->valueless_by_exception()) {
735 __visitation::__base::__visit_alt(
736 [](auto& __alt) noexcept {
737 using __alt_type = decay_t<decltype(__alt)>;
742 this->__index = __variant_npos;
745 _LIBCPP_VARIANT_DESTRUCTOR(
746 _Trait::_Unavailable,
747 ~__destructor() = delete;,
748 void __destroy() noexcept = delete;);
750 #undef _LIBCPP_VARIANT_DESTRUCTOR
752 template <class _Traits>
753 class _LIBCPP_TEMPLATE_VIS __constructor : public __destructor<_Traits> {
754 using __base_type = __destructor<_Traits>;
757 using __base_type::__base_type;
758 using __base_type::operator=;
761 template <size_t _Ip, class _Tp, class... _Args>
762 inline _LIBCPP_INLINE_VISIBILITY
763 static void __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) {
764 ::new (_VSTD::addressof(__a))
765 __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...);
768 template <class _Rhs>
769 inline _LIBCPP_INLINE_VISIBILITY
770 static void __generic_construct(__constructor& __lhs, _Rhs&& __rhs) {
772 if (!__rhs.valueless_by_exception()) {
773 __visitation::__base::__visit_alt_at(
775 [](auto& __lhs_alt, auto&& __rhs_alt) {
778 _VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value);
780 __lhs, _VSTD::forward<_Rhs>(__rhs));
781 __lhs.__index = __rhs.index();
786 template <class _Traits, _Trait = _Traits::__move_constructible_trait>
787 class _LIBCPP_TEMPLATE_VIS __move_constructor;
789 #define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, \
791 template <class... _Types> \
792 class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>, \
793 move_constructible_trait> \
794 : public __constructor<__traits<_Types...>> { \
795 using __base_type = __constructor<__traits<_Types...>>; \
798 using __base_type::__base_type; \
799 using __base_type::operator=; \
801 __move_constructor(const __move_constructor&) = default; \
803 ~__move_constructor() = default; \
804 __move_constructor& operator=(const __move_constructor&) = default; \
805 __move_constructor& operator=(__move_constructor&&) = default; \
808 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
809 _Trait::_TriviallyAvailable,
810 __move_constructor(__move_constructor&& __that) = default;);
812 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
814 __move_constructor(__move_constructor&& __that) noexcept(
815 __all<is_nothrow_move_constructible_v<_Types>...>::value)
816 : __move_constructor(__valueless_t{}) {
817 this->__generic_construct(*this, _VSTD::move(__that));
820 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
821 _Trait::_Unavailable,
822 __move_constructor(__move_constructor&&) = delete;);
824 #undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR
826 template <class _Traits, _Trait = _Traits::__copy_constructible_trait>
827 class _LIBCPP_TEMPLATE_VIS __copy_constructor;
829 #define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, \
831 template <class... _Types> \
832 class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \
833 copy_constructible_trait> \
834 : public __move_constructor<__traits<_Types...>> { \
835 using __base_type = __move_constructor<__traits<_Types...>>; \
838 using __base_type::__base_type; \
839 using __base_type::operator=; \
842 __copy_constructor(__copy_constructor&&) = default; \
843 ~__copy_constructor() = default; \
844 __copy_constructor& operator=(const __copy_constructor&) = default; \
845 __copy_constructor& operator=(__copy_constructor&&) = default; \
848 _LIBCPP_VARIANT_COPY_CONSTRUCTOR(
849 _Trait::_TriviallyAvailable,
850 __copy_constructor(const __copy_constructor& __that) = default;);
852 _LIBCPP_VARIANT_COPY_CONSTRUCTOR(
854 __copy_constructor(const __copy_constructor& __that)
855 : __copy_constructor(__valueless_t{}) {
856 this->__generic_construct(*this, __that);
859 _LIBCPP_VARIANT_COPY_CONSTRUCTOR(
860 _Trait::_Unavailable,
861 __copy_constructor(const __copy_constructor&) = delete;);
863 #undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR
865 template <class _Traits>
866 class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> {
867 using __base_type = __copy_constructor<_Traits>;
870 using __base_type::__base_type;
871 using __base_type::operator=;
873 template <size_t _Ip, class... _Args>
874 inline _LIBCPP_INLINE_VISIBILITY
875 void __emplace(_Args&&... __args) {
877 this->__construct_alt(__access::__base::__get_alt<_Ip>(*this),
878 _VSTD::forward<_Args>(__args)...);
883 template <bool _CopyAssign, size_t _Ip, class _Tp, class _Arg>
884 inline _LIBCPP_INLINE_VISIBILITY
885 void __assign_alt(__alt<_Ip, _Tp>& __a,
887 bool_constant<_CopyAssign> __tag) {
888 if (this->index() == _Ip) {
889 __a.__value = _VSTD::forward<_Arg>(__arg);
892 void operator()(true_type) const {
893 __this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg)));
895 void operator()(false_type) const {
896 __this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg));
898 __assignment* __this;
900 } __impl{this, _VSTD::forward<_Arg>(__arg)};
905 template <class _That>
906 inline _LIBCPP_INLINE_VISIBILITY
907 void __generic_assign(_That&& __that) {
908 if (this->valueless_by_exception() && __that.valueless_by_exception()) {
910 } else if (__that.valueless_by_exception()) {
913 __visitation::__base::__visit_alt_at(
915 [this](auto& __this_alt, auto&& __that_alt) {
918 _VSTD::forward<decltype(__that_alt)>(__that_alt).__value,
919 is_lvalue_reference<_That>{});
921 *this, _VSTD::forward<_That>(__that));
926 template <class _Traits, _Trait = _Traits::__move_assignable_trait>
927 class _LIBCPP_TEMPLATE_VIS __move_assignment;
929 #define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, \
931 template <class... _Types> \
932 class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \
933 move_assignable_trait> \
934 : public __assignment<__traits<_Types...>> { \
935 using __base_type = __assignment<__traits<_Types...>>; \
938 using __base_type::__base_type; \
939 using __base_type::operator=; \
941 __move_assignment(const __move_assignment&) = default; \
942 __move_assignment(__move_assignment&&) = default; \
943 ~__move_assignment() = default; \
944 __move_assignment& operator=(const __move_assignment&) = default; \
948 _LIBCPP_VARIANT_MOVE_ASSIGNMENT(
949 _Trait::_TriviallyAvailable,
950 __move_assignment& operator=(__move_assignment&& __that) = default;);
952 _LIBCPP_VARIANT_MOVE_ASSIGNMENT(
954 __move_assignment& operator=(__move_assignment&& __that) noexcept(
955 __all<(is_nothrow_move_constructible_v<_Types> &&
956 is_nothrow_move_assignable_v<_Types>)...>::value) {
957 this->__generic_assign(_VSTD::move(__that));
961 _LIBCPP_VARIANT_MOVE_ASSIGNMENT(
962 _Trait::_Unavailable,
963 __move_assignment& operator=(__move_assignment&&) = delete;);
965 #undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT
967 template <class _Traits, _Trait = _Traits::__copy_assignable_trait>
968 class _LIBCPP_TEMPLATE_VIS __copy_assignment;
970 #define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, \
972 template <class... _Types> \
973 class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \
974 copy_assignable_trait> \
975 : public __move_assignment<__traits<_Types...>> { \
976 using __base_type = __move_assignment<__traits<_Types...>>; \
979 using __base_type::__base_type; \
980 using __base_type::operator=; \
982 __copy_assignment(const __copy_assignment&) = default; \
983 __copy_assignment(__copy_assignment&&) = default; \
984 ~__copy_assignment() = default; \
986 __copy_assignment& operator=(__copy_assignment&&) = default; \
989 _LIBCPP_VARIANT_COPY_ASSIGNMENT(
990 _Trait::_TriviallyAvailable,
991 __copy_assignment& operator=(const __copy_assignment& __that) = default;);
993 _LIBCPP_VARIANT_COPY_ASSIGNMENT(
995 __copy_assignment& operator=(const __copy_assignment& __that) {
996 this->__generic_assign(__that);
1000 _LIBCPP_VARIANT_COPY_ASSIGNMENT(
1001 _Trait::_Unavailable,
1002 __copy_assignment& operator=(const __copy_assignment&) = delete;);
1004 #undef _LIBCPP_VARIANT_COPY_ASSIGNMENT
1006 template <class... _Types>
1007 class _LIBCPP_TEMPLATE_VIS __impl
1008 : public __copy_assignment<__traits<_Types...>> {
1009 using __base_type = __copy_assignment<__traits<_Types...>>;
1012 using __base_type::__base_type;
1013 using __base_type::operator=;
1015 template <size_t _Ip, class _Arg>
1016 inline _LIBCPP_INLINE_VISIBILITY
1017 void __assign(_Arg&& __arg) {
1018 this->__assign_alt(__access::__base::__get_alt<_Ip>(*this),
1019 _VSTD::forward<_Arg>(__arg),
1023 inline _LIBCPP_INLINE_VISIBILITY
1024 void __swap(__impl& __that) {
1025 if (this->valueless_by_exception() && __that.valueless_by_exception()) {
1027 } else if (this->index() == __that.index()) {
1028 __visitation::__base::__visit_alt_at(
1030 [](auto& __this_alt, auto& __that_alt) {
1032 swap(__this_alt.__value, __that_alt.__value);
1037 __impl* __lhs = this;
1038 __impl* __rhs = _VSTD::addressof(__that);
1039 if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) {
1040 _VSTD::swap(__lhs, __rhs);
1042 __impl __tmp(_VSTD::move(*__rhs));
1043 #ifndef _LIBCPP_NO_EXCEPTIONS
1044 // EXTENSION: When the move construction of `__lhs` into `__rhs` throws
1045 // and `__tmp` is nothrow move constructible then we move `__tmp` back
1046 // into `__rhs` and provide the strong exception safety guarentee.
1048 this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
1050 if (__tmp.__move_nothrow()) {
1051 this->__generic_construct(*__rhs, _VSTD::move(__tmp));
1056 this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
1058 this->__generic_construct(*__lhs, _VSTD::move(__tmp));
1063 inline _LIBCPP_INLINE_VISIBILITY
1064 bool __move_nothrow() const {
1065 constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...};
1066 return this->valueless_by_exception() || __results[this->index()];
1070 template <class... _Types>
1074 struct __overload<> { void operator()() const; };
1076 template <class _Tp, class... _Types>
1077 struct __overload<_Tp, _Types...> : __overload<_Types...> {
1078 using __overload<_Types...>::operator();
1079 __identity<_Tp> operator()(_Tp) const;
1082 template <class _Tp, class... _Types>
1083 using __best_match_t = typename result_of_t<__overload<_Types...>(_Tp&&)>::type;
1085 } // __variant_detail
1087 template <class... _Types>
1088 class _LIBCPP_TEMPLATE_VIS variant
1089 : private __sfinae_ctor_base<
1090 __all<is_copy_constructible_v<_Types>...>::value,
1091 __all<is_move_constructible_v<_Types>...>::value>,
1092 private __sfinae_assign_base<
1093 __all<(is_copy_constructible_v<_Types> &&
1094 is_move_constructible_v<_Types> &&
1095 is_copy_assignable_v<_Types>)...>::value,
1096 __all<(is_move_constructible_v<_Types> &&
1097 is_move_assignable_v<_Types>)...>::value> {
1098 static_assert(0 < sizeof...(_Types),
1099 "variant must consist of at least one alternative.");
1101 static_assert(__all<!is_array_v<_Types>...>::value,
1102 "variant can not have an array type as an alternative.");
1104 static_assert(__all<!is_reference_v<_Types>...>::value,
1105 "variant can not have a reference type as an alternative.");
1107 static_assert(__all<!is_void_v<_Types>...>::value,
1108 "variant can not have a void type as an alternative.");
1110 using __first_type = variant_alternative_t<0, variant>;
1113 template <bool _Dummy = true,
1114 enable_if_t<__dependent_type<is_default_constructible<__first_type>,
1117 inline _LIBCPP_INLINE_VISIBILITY
1118 constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>)
1119 : __impl(in_place_index<0>) {}
1121 variant(const variant&) = default;
1122 variant(variant&&) = default;
1126 enable_if_t<!is_same_v<decay_t<_Arg>, variant>, int> = 0,
1127 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
1129 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1130 enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0>
1131 inline _LIBCPP_INLINE_VISIBILITY
1132 constexpr variant(_Arg&& __arg) noexcept(
1133 is_nothrow_constructible_v<_Tp, _Arg>)
1134 : __impl(in_place_index<_Ip>, _VSTD::forward<_Arg>(__arg)) {}
1136 template <size_t _Ip, class... _Args,
1137 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
1138 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1139 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1140 inline _LIBCPP_INLINE_VISIBILITY
1141 explicit constexpr variant(
1142 in_place_index_t<_Ip>,
1143 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>)
1144 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {}
1150 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
1151 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1152 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1154 inline _LIBCPP_INLINE_VISIBILITY
1155 explicit constexpr variant(
1156 in_place_index_t<_Ip>,
1157 initializer_list<_Up> __il,
1158 _Args&&... __args) noexcept(
1159 is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>)
1160 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {}
1166 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1167 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1168 inline _LIBCPP_INLINE_VISIBILITY
1169 explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept(
1170 is_nothrow_constructible_v<_Tp, _Args...>)
1171 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {}
1178 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1179 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1181 inline _LIBCPP_INLINE_VISIBILITY
1182 explicit constexpr variant(
1183 in_place_type_t<_Tp>,
1184 initializer_list<_Up> __il,
1185 _Args&&... __args) noexcept(
1186 is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>)
1187 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {}
1189 ~variant() = default;
1191 variant& operator=(const variant&) = default;
1192 variant& operator=(variant&&) = default;
1196 enable_if_t<!is_same_v<decay_t<_Arg>, variant>, int> = 0,
1197 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
1199 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1200 enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>,
1202 inline _LIBCPP_INLINE_VISIBILITY
1203 variant& operator=(_Arg&& __arg) noexcept(
1204 is_nothrow_assignable_v<_Tp&, _Arg> &&
1205 is_nothrow_constructible_v<_Tp, _Arg>) {
1206 __impl.template __assign<_Ip>(_VSTD::forward<_Arg>(__arg));
1213 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
1214 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1215 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1216 inline _LIBCPP_INLINE_VISIBILITY
1217 void emplace(_Args&&... __args) {
1218 __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...);
1225 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
1226 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1227 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1229 inline _LIBCPP_INLINE_VISIBILITY
1230 void emplace(initializer_list<_Up> __il, _Args&&... __args) {
1231 __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...);
1238 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1239 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1240 inline _LIBCPP_INLINE_VISIBILITY
1241 void emplace(_Args&&... __args) {
1242 __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...);
1250 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1251 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1253 inline _LIBCPP_INLINE_VISIBILITY
1254 void emplace(initializer_list<_Up> __il, _Args&&... __args) {
1255 __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...);
1258 inline _LIBCPP_INLINE_VISIBILITY
1259 constexpr bool valueless_by_exception() const noexcept {
1260 return __impl.valueless_by_exception();
1263 inline _LIBCPP_INLINE_VISIBILITY
1264 constexpr size_t index() const noexcept { return __impl.index(); }
1270 __dependent_type<is_move_constructible<_Types>, _Dummy>::value &&
1271 __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value,
1273 inline _LIBCPP_INLINE_VISIBILITY
1274 void swap(variant& __that) noexcept(
1275 __all<(is_nothrow_move_constructible_v<_Types> &&
1276 is_nothrow_swappable_v<_Types>)...>::value) {
1277 __impl.__swap(__that.__impl);
1281 __variant_detail::__impl<_Types...> __impl;
1283 friend struct __variant_detail::__access::__variant;
1284 friend struct __variant_detail::__visitation::__variant;
1287 template <size_t _Ip, class... _Types>
1288 inline _LIBCPP_INLINE_VISIBILITY
1289 constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept {
1290 return __v.index() == _Ip;
1293 template <class _Tp, class... _Types>
1294 inline _LIBCPP_INLINE_VISIBILITY
1295 constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept {
1296 return __holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1299 template <size_t _Ip, class _Vp>
1300 inline _LIBCPP_INLINE_VISIBILITY
1301 static constexpr auto&& __generic_get(_Vp&& __v) {
1302 using __variant_detail::__access::__variant;
1303 if (!__holds_alternative<_Ip>(__v)) {
1304 __throw_bad_variant_access();
1306 return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value;
1309 template <size_t _Ip, class... _Types>
1310 inline _LIBCPP_INLINE_VISIBILITY
1311 constexpr variant_alternative_t<_Ip, variant<_Types...>>& get(
1312 variant<_Types...>& __v) {
1313 static_assert(_Ip < sizeof...(_Types));
1314 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1315 return __generic_get<_Ip>(__v);
1318 template <size_t _Ip, class... _Types>
1319 inline _LIBCPP_INLINE_VISIBILITY
1320 constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get(
1321 variant<_Types...>&& __v) {
1322 static_assert(_Ip < sizeof...(_Types));
1323 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1324 return __generic_get<_Ip>(_VSTD::move(__v));
1327 template <size_t _Ip, class... _Types>
1328 inline _LIBCPP_INLINE_VISIBILITY
1329 constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get(
1330 const variant<_Types...>& __v) {
1331 static_assert(_Ip < sizeof...(_Types));
1332 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1333 return __generic_get<_Ip>(__v);
1336 template <size_t _Ip, class... _Types>
1337 inline _LIBCPP_INLINE_VISIBILITY
1338 constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get(
1339 const variant<_Types...>&& __v) {
1340 static_assert(_Ip < sizeof...(_Types));
1341 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1342 return __generic_get<_Ip>(_VSTD::move(__v));
1345 template <class _Tp, class... _Types>
1346 inline _LIBCPP_INLINE_VISIBILITY
1347 constexpr _Tp& get(variant<_Types...>& __v) {
1348 static_assert(!is_void_v<_Tp>);
1349 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1352 template <class _Tp, class... _Types>
1353 inline _LIBCPP_INLINE_VISIBILITY
1354 constexpr _Tp&& get(variant<_Types...>&& __v) {
1355 static_assert(!is_void_v<_Tp>);
1356 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(
1360 template <class _Tp, class... _Types>
1361 inline _LIBCPP_INLINE_VISIBILITY
1362 constexpr const _Tp& get(const variant<_Types...>& __v) {
1363 static_assert(!is_void_v<_Tp>);
1364 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1367 template <class _Tp, class... _Types>
1368 inline _LIBCPP_INLINE_VISIBILITY
1369 constexpr const _Tp&& get(const variant<_Types...>&& __v) {
1370 static_assert(!is_void_v<_Tp>);
1371 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(
1375 template <size_t _Ip, class _Vp>
1376 inline _LIBCPP_INLINE_VISIBILITY
1377 constexpr auto* __generic_get_if(_Vp* __v) noexcept {
1378 using __variant_detail::__access::__variant;
1379 return __v && __holds_alternative<_Ip>(*__v)
1380 ? _VSTD::addressof(__variant::__get_alt<_Ip>(*__v).__value)
1384 template <size_t _Ip, class... _Types>
1385 inline _LIBCPP_INLINE_VISIBILITY
1386 constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>>
1387 get_if(variant<_Types...>* __v) noexcept {
1388 static_assert(_Ip < sizeof...(_Types));
1389 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1390 return __generic_get_if<_Ip>(__v);
1393 template <size_t _Ip, class... _Types>
1394 inline _LIBCPP_INLINE_VISIBILITY
1395 constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>>
1396 get_if(const variant<_Types...>* __v) noexcept {
1397 static_assert(_Ip < sizeof...(_Types));
1398 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1399 return __generic_get_if<_Ip>(__v);
1402 template <class _Tp, class... _Types>
1403 inline _LIBCPP_INLINE_VISIBILITY
1404 constexpr add_pointer_t<_Tp>
1405 get_if(variant<_Types...>* __v) noexcept {
1406 static_assert(!is_void_v<_Tp>);
1407 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1410 template <class _Tp, class... _Types>
1411 inline _LIBCPP_INLINE_VISIBILITY
1412 constexpr add_pointer_t<const _Tp>
1413 get_if(const variant<_Types...>* __v) noexcept {
1414 static_assert(!is_void_v<_Tp>);
1415 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1418 template <class... _Types>
1419 inline _LIBCPP_INLINE_VISIBILITY
1420 constexpr bool operator==(const variant<_Types...>& __lhs,
1421 const variant<_Types...>& __rhs) {
1422 using __variant_detail::__visitation::__variant;
1423 if (__lhs.index() != __rhs.index()) return false;
1424 if (__lhs.valueless_by_exception()) return true;
1425 return __variant::__visit_value_at(__lhs.index(), equal_to<>{}, __lhs, __rhs);
1428 template <class... _Types>
1429 inline _LIBCPP_INLINE_VISIBILITY
1430 constexpr bool operator!=(const variant<_Types...>& __lhs,
1431 const variant<_Types...>& __rhs) {
1432 using __variant_detail::__visitation::__variant;
1433 if (__lhs.index() != __rhs.index()) return true;
1434 if (__lhs.valueless_by_exception()) return false;
1435 return __variant::__visit_value_at(
1436 __lhs.index(), not_equal_to<>{}, __lhs, __rhs);
1439 template <class... _Types>
1440 inline _LIBCPP_INLINE_VISIBILITY
1441 constexpr bool operator<(const variant<_Types...>& __lhs,
1442 const variant<_Types...>& __rhs) {
1443 using __variant_detail::__visitation::__variant;
1444 if (__rhs.valueless_by_exception()) return false;
1445 if (__lhs.valueless_by_exception()) return true;
1446 if (__lhs.index() < __rhs.index()) return true;
1447 if (__lhs.index() > __rhs.index()) return false;
1448 return __variant::__visit_value_at(__lhs.index(), less<>{}, __lhs, __rhs);
1451 template <class... _Types>
1452 inline _LIBCPP_INLINE_VISIBILITY
1453 constexpr bool operator>(const variant<_Types...>& __lhs,
1454 const variant<_Types...>& __rhs) {
1455 using __variant_detail::__visitation::__variant;
1456 if (__lhs.valueless_by_exception()) return false;
1457 if (__rhs.valueless_by_exception()) return true;
1458 if (__lhs.index() > __rhs.index()) return true;
1459 if (__lhs.index() < __rhs.index()) return false;
1460 return __variant::__visit_value_at(__lhs.index(), greater<>{}, __lhs, __rhs);
1463 template <class... _Types>
1464 inline _LIBCPP_INLINE_VISIBILITY
1465 constexpr bool operator<=(const variant<_Types...>& __lhs,
1466 const variant<_Types...>& __rhs) {
1467 using __variant_detail::__visitation::__variant;
1468 if (__lhs.valueless_by_exception()) return true;
1469 if (__rhs.valueless_by_exception()) return false;
1470 if (__lhs.index() < __rhs.index()) return true;
1471 if (__lhs.index() > __rhs.index()) return false;
1472 return __variant::__visit_value_at(
1473 __lhs.index(), less_equal<>{}, __lhs, __rhs);
1476 template <class... _Types>
1477 inline _LIBCPP_INLINE_VISIBILITY
1478 constexpr bool operator>=(const variant<_Types...>& __lhs,
1479 const variant<_Types...>& __rhs) {
1480 using __variant_detail::__visitation::__variant;
1481 if (__rhs.valueless_by_exception()) return true;
1482 if (__lhs.valueless_by_exception()) return false;
1483 if (__lhs.index() > __rhs.index()) return true;
1484 if (__lhs.index() < __rhs.index()) return false;
1485 return __variant::__visit_value_at(
1486 __lhs.index(), greater_equal<>{}, __lhs, __rhs);
1489 template <class _Visitor, class... _Vs>
1490 inline _LIBCPP_INLINE_VISIBILITY
1491 constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) {
1492 using __variant_detail::__visitation::__variant;
1493 bool __results[] = {__vs.valueless_by_exception()...};
1494 for (bool __result : __results) {
1496 __throw_bad_variant_access();
1499 return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor),
1500 _VSTD::forward<_Vs>(__vs)...);
1503 struct _LIBCPP_TEMPLATE_VIS monostate {};
1505 inline _LIBCPP_INLINE_VISIBILITY
1506 constexpr bool operator<(monostate, monostate) noexcept { return false; }
1508 inline _LIBCPP_INLINE_VISIBILITY
1509 constexpr bool operator>(monostate, monostate) noexcept { return false; }
1511 inline _LIBCPP_INLINE_VISIBILITY
1512 constexpr bool operator<=(monostate, monostate) noexcept { return true; }
1514 inline _LIBCPP_INLINE_VISIBILITY
1515 constexpr bool operator>=(monostate, monostate) noexcept { return true; }
1517 inline _LIBCPP_INLINE_VISIBILITY
1518 constexpr bool operator==(monostate, monostate) noexcept { return true; }
1520 inline _LIBCPP_INLINE_VISIBILITY
1521 constexpr bool operator!=(monostate, monostate) noexcept { return false; }
1523 template <class... _Types>
1524 inline _LIBCPP_INLINE_VISIBILITY
1525 auto swap(variant<_Types...>& __lhs,
1526 variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs)))
1527 -> decltype(__lhs.swap(__rhs)) {
1531 template <class... _Types>
1532 struct _LIBCPP_TEMPLATE_VIS hash<variant<_Types...>> {
1533 using argument_type = variant<_Types...>;
1534 using result_type = size_t;
1536 inline _LIBCPP_INLINE_VISIBILITY
1537 result_type operator()(const argument_type& __v) const {
1538 using __variant_detail::__visitation::__variant;
1540 __v.valueless_by_exception()
1541 ? 299792458 // Random value chosen by the universe upon creation
1542 : __variant::__visit_alt(
1543 [](const auto& __alt) {
1544 using __alt_type = decay_t<decltype(__alt)>;
1545 using __value_type = typename __alt_type::__value_type;
1546 return hash<__value_type>{}(__alt.__value);
1549 return __hash_combine(__res, hash<size_t>{}(__v.index()));
1554 struct _LIBCPP_TEMPLATE_VIS hash<monostate> {
1555 using argument_type = monostate;
1556 using result_type = size_t;
1558 inline _LIBCPP_INLINE_VISIBILITY
1559 result_type operator()(const argument_type&) const {
1560 return 66740831; // return a fundamentally attractive random value.
1564 #endif // _LIBCPP_STD_VER > 14
1566 _LIBCPP_END_NAMESPACE_STD
1568 #endif // _LIBCPP_VARIANT