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 T& emplace(Args&&...);
58 template <class T, class U, class... Args>
59 T& emplace(initializer_list<U>, Args&&...);
61 template <size_t I, class... Args>
62 variant_alternative_t<I, variant>& emplace(Args&&...);
64 template <size_t I, class U, class... Args>
65 variant_alternative_t<I, variant>& 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), "Index out of bounds in std::variant_alternative<>");
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 __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...});
363 static constexpr _Trait __move_assignable_trait = __common_trait(
364 {__move_constructible_trait,
365 __trait<_Types, is_trivially_move_assignable, is_move_assignable>...});
367 static constexpr _Trait __destructible_trait = __common_trait(
368 {__trait<_Types, is_trivially_destructible, is_destructible>...});
375 inline _LIBCPP_INLINE_VISIBILITY
376 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) {
377 return _VSTD::forward<_Vp>(__v).__head;
380 template <class _Vp, size_t _Ip>
381 inline _LIBCPP_INLINE_VISIBILITY
382 static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) {
383 return __get_alt(_VSTD::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>);
388 template <size_t _Ip, class _Vp>
389 inline _LIBCPP_INLINE_VISIBILITY
390 static constexpr auto&& __get_alt(_Vp&& __v) {
391 return __union::__get_alt(_VSTD::forward<_Vp>(__v).__data,
392 in_place_index<_Ip>);
397 template <size_t _Ip, class _Vp>
398 inline _LIBCPP_INLINE_VISIBILITY
399 static constexpr auto&& __get_alt(_Vp&& __v) {
400 return __base::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v).__impl);
404 } // namespace __access
406 namespace __visitation {
409 template <class _Visitor, class... _Vs>
410 inline _LIBCPP_INLINE_VISIBILITY
411 static constexpr decltype(auto)
412 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
413 constexpr auto __fdiagonal =
414 __make_fdiagonal<_Visitor&&,
415 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
416 return __fdiagonal[__index](_VSTD::forward<_Visitor>(__visitor),
417 _VSTD::forward<_Vs>(__vs).__as_base()...);
420 template <class _Visitor, class... _Vs>
421 inline _LIBCPP_INLINE_VISIBILITY
422 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
424 constexpr auto __fmatrix =
425 __make_fmatrix<_Visitor&&,
426 decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
427 return __at(__fmatrix, __vs.index()...)(
428 _VSTD::forward<_Visitor>(__visitor),
429 _VSTD::forward<_Vs>(__vs).__as_base()...);
434 inline _LIBCPP_INLINE_VISIBILITY
435 static constexpr const _Tp& __at(const _Tp& __elem) { return __elem; }
437 template <class _Tp, size_t _Np, typename... _Indices>
438 inline _LIBCPP_INLINE_VISIBILITY
439 static constexpr auto&& __at(const array<_Tp, _Np>& __elems,
440 size_t __index, _Indices... __indices) {
441 return __at(__elems[__index], __indices...);
444 template <class _Fp, class... _Fs>
445 static constexpr void __std_visit_visitor_return_type_check() {
447 __all<is_same_v<_Fp, _Fs>...>::value,
448 "`std::visit` requires the visitor to have a single return type.");
451 template <class... _Fs>
452 inline _LIBCPP_INLINE_VISIBILITY
453 static constexpr auto __make_farray(_Fs&&... __fs) {
454 __std_visit_visitor_return_type_check<decay_t<_Fs>...>();
455 using __result = array<common_type_t<decay_t<_Fs>...>, sizeof...(_Fs)>;
456 return __result{{_VSTD::forward<_Fs>(__fs)...}};
459 template <std::size_t... _Is>
460 struct __dispatcher {
461 template <class _Fp, class... _Vs>
462 inline _LIBCPP_INLINE_VISIBILITY
463 static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) {
464 return __invoke_constexpr(
465 static_cast<_Fp>(__f),
466 __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...);
470 template <class _Fp, class... _Vs, size_t... _Is>
471 inline _LIBCPP_INLINE_VISIBILITY
472 static constexpr auto __make_dispatch(index_sequence<_Is...>) {
473 return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>;
476 template <size_t _Ip, class _Fp, class... _Vs>
477 inline _LIBCPP_INLINE_VISIBILITY
478 static constexpr auto __make_fdiagonal_impl() {
479 return __make_dispatch<_Fp, _Vs...>(
480 index_sequence<(__identity<_Vs>{}, _Ip)...>{});
483 template <class _Fp, class... _Vs, size_t... _Is>
484 inline _LIBCPP_INLINE_VISIBILITY
485 static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) {
486 return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...);
489 template <class _Fp, class _Vp, class... _Vs>
490 inline _LIBCPP_INLINE_VISIBILITY
491 static constexpr auto __make_fdiagonal() {
492 constexpr size_t _Np = decay_t<_Vp>::__size();
493 static_assert(__all<(_Np == decay_t<_Vs>::__size())...>::value);
494 return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<_Np>{});
497 template <class _Fp, class... _Vs, size_t... _Is>
498 inline _LIBCPP_INLINE_VISIBILITY
499 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) {
500 return __make_dispatch<_Fp, _Vs...>(__is);
503 template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls>
504 inline _LIBCPP_INLINE_VISIBILITY
505 static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>,
506 index_sequence<_Js...>,
508 return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>(
509 index_sequence<_Is..., _Js>{}, __ls...)...);
512 template <class _Fp, class... _Vs>
513 inline _LIBCPP_INLINE_VISIBILITY
514 static constexpr auto __make_fmatrix() {
515 return __make_fmatrix_impl<_Fp, _Vs...>(
516 index_sequence<>{}, make_index_sequence<decay_t<_Vs>::__size()>{}...);
521 template <class _Visitor, class... _Vs>
522 inline _LIBCPP_INLINE_VISIBILITY
523 static constexpr decltype(auto)
524 __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
525 return __base::__visit_alt_at(__index,
526 _VSTD::forward<_Visitor>(__visitor),
527 _VSTD::forward<_Vs>(__vs).__impl...);
530 template <class _Visitor, class... _Vs>
531 inline _LIBCPP_INLINE_VISIBILITY
532 static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
534 return __base::__visit_alt(_VSTD::forward<_Visitor>(__visitor),
535 _VSTD::forward<_Vs>(__vs).__impl...);
538 template <class _Visitor, class... _Vs>
539 inline _LIBCPP_INLINE_VISIBILITY
540 static constexpr decltype(auto)
541 __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
542 return __visit_alt_at(
544 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
545 _VSTD::forward<_Vs>(__vs)...);
548 template <class _Visitor, class... _Vs>
549 inline _LIBCPP_INLINE_VISIBILITY
550 static constexpr decltype(auto) __visit_value(_Visitor&& __visitor,
553 __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
554 _VSTD::forward<_Vs>(__vs)...);
558 template <class _Visitor, class... _Values>
559 static constexpr void __std_visit_exhaustive_visitor_check() {
560 static_assert(is_callable_v<_Visitor(_Values...)>,
561 "`std::visit` requires the visitor to be exhaustive.");
564 template <class _Visitor>
565 struct __value_visitor {
566 template <class... _Alts>
567 inline _LIBCPP_INLINE_VISIBILITY
568 constexpr decltype(auto) operator()(_Alts&&... __alts) const {
569 __std_visit_exhaustive_visitor_check<
571 decltype((_VSTD::forward<_Alts>(__alts).__value))...>();
572 return __invoke_constexpr(_VSTD::forward<_Visitor>(__visitor),
573 _VSTD::forward<_Alts>(__alts).__value...);
575 _Visitor&& __visitor;
578 template <class _Visitor>
579 inline _LIBCPP_INLINE_VISIBILITY
580 static constexpr auto __make_value_visitor(_Visitor&& __visitor) {
581 return __value_visitor<_Visitor>{_VSTD::forward<_Visitor>(__visitor)};
585 } // namespace __visitation
587 template <size_t _Index, class _Tp>
588 struct _LIBCPP_TEMPLATE_VIS __alt {
589 using __value_type = _Tp;
591 template <class... _Args>
592 inline _LIBCPP_INLINE_VISIBILITY
593 explicit constexpr __alt(in_place_t, _Args&&... __args)
594 : __value(_VSTD::forward<_Args>(__args)...) {}
596 __value_type __value;
599 template <_Trait _DestructibleTrait, size_t _Index, class... _Types>
600 union _LIBCPP_TEMPLATE_VIS __union;
602 template <_Trait _DestructibleTrait, size_t _Index>
603 union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {};
605 #define _LIBCPP_VARIANT_UNION(destructible_trait, destructor) \
606 template <size_t _Index, class _Tp, class... _Types> \
607 union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, \
612 inline _LIBCPP_INLINE_VISIBILITY \
613 explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \
615 template <class... _Args> \
616 inline _LIBCPP_INLINE_VISIBILITY \
617 explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \
618 : __head(in_place, _VSTD::forward<_Args>(__args)...) {} \
620 template <size_t _Ip, class... _Args> \
621 inline _LIBCPP_INLINE_VISIBILITY \
622 explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \
623 : __tail(in_place_index<_Ip - 1>, _VSTD::forward<_Args>(__args)...) {} \
625 __union(const __union&) = default; \
626 __union(__union&&) = default; \
630 __union& operator=(const __union&) = default; \
631 __union& operator=(__union&&) = default; \
635 __alt<_Index, _Tp> __head; \
636 __union<destructible_trait, _Index + 1, _Types...> __tail; \
638 friend struct __access::__union; \
641 _LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;);
642 _LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {});
643 _LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;);
645 #undef _LIBCPP_VARIANT_UNION
647 template <_Trait _DestructibleTrait, class... _Types>
648 class _LIBCPP_TEMPLATE_VIS __base {
650 inline _LIBCPP_INLINE_VISIBILITY
651 explicit constexpr __base(__valueless_t tag) noexcept
652 : __data(tag), __index(__variant_npos) {}
654 template <size_t _Ip, class... _Args>
655 inline _LIBCPP_INLINE_VISIBILITY
656 explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args)
658 __data(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...),
661 inline _LIBCPP_INLINE_VISIBILITY
662 constexpr bool valueless_by_exception() const noexcept {
663 return index() == variant_npos;
666 inline _LIBCPP_INLINE_VISIBILITY
667 constexpr size_t index() const noexcept {
668 return __index == __variant_npos ? variant_npos : __index;
672 inline _LIBCPP_INLINE_VISIBILITY
673 constexpr auto&& __as_base() & { return *this; }
675 inline _LIBCPP_INLINE_VISIBILITY
676 constexpr auto&& __as_base() && { return _VSTD::move(*this); }
678 inline _LIBCPP_INLINE_VISIBILITY
679 constexpr auto&& __as_base() const & { return *this; }
681 inline _LIBCPP_INLINE_VISIBILITY
682 constexpr auto&& __as_base() const && { return _VSTD::move(*this); }
684 inline _LIBCPP_INLINE_VISIBILITY
685 static constexpr size_t __size() { return sizeof...(_Types); }
687 __union<_DestructibleTrait, 0, _Types...> __data;
688 unsigned int __index;
690 friend struct __access::__base;
691 friend struct __visitation::__base;
694 template <class _Traits, _Trait = _Traits::__destructible_trait>
695 class _LIBCPP_TEMPLATE_VIS __destructor;
697 #define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy) \
698 template <class... _Types> \
699 class _LIBCPP_TEMPLATE_VIS __destructor<__traits<_Types...>, \
700 destructible_trait> \
701 : public __base<destructible_trait, _Types...> { \
702 using __base_type = __base<destructible_trait, _Types...>; \
705 using __base_type::__base_type; \
706 using __base_type::operator=; \
708 __destructor(const __destructor&) = default; \
709 __destructor(__destructor&&) = default; \
711 __destructor& operator=(const __destructor&) = default; \
712 __destructor& operator=(__destructor&&) = default; \
715 inline _LIBCPP_INLINE_VISIBILITY \
719 _LIBCPP_VARIANT_DESTRUCTOR(
720 _Trait::_TriviallyAvailable,
721 ~__destructor() = default;,
722 void __destroy() noexcept { this->__index = __variant_npos; });
724 _LIBCPP_VARIANT_DESTRUCTOR(
726 ~__destructor() { __destroy(); },
727 void __destroy() noexcept {
728 if (!this->valueless_by_exception()) {
729 __visitation::__base::__visit_alt(
730 [](auto& __alt) noexcept {
731 using __alt_type = decay_t<decltype(__alt)>;
736 this->__index = __variant_npos;
739 _LIBCPP_VARIANT_DESTRUCTOR(
740 _Trait::_Unavailable,
741 ~__destructor() = delete;,
742 void __destroy() noexcept = delete;);
744 #undef _LIBCPP_VARIANT_DESTRUCTOR
746 template <class _Traits>
747 class _LIBCPP_TEMPLATE_VIS __constructor : public __destructor<_Traits> {
748 using __base_type = __destructor<_Traits>;
751 using __base_type::__base_type;
752 using __base_type::operator=;
755 template <size_t _Ip, class _Tp, class... _Args>
756 inline _LIBCPP_INLINE_VISIBILITY
757 static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) {
758 ::new ((void*)_VSTD::addressof(__a))
759 __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...);
763 template <class _Rhs>
764 inline _LIBCPP_INLINE_VISIBILITY
765 static void __generic_construct(__constructor& __lhs, _Rhs&& __rhs) {
767 if (!__rhs.valueless_by_exception()) {
768 __visitation::__base::__visit_alt_at(
770 [](auto& __lhs_alt, auto&& __rhs_alt) {
773 _VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value);
775 __lhs, _VSTD::forward<_Rhs>(__rhs));
776 __lhs.__index = __rhs.index();
781 template <class _Traits, _Trait = _Traits::__move_constructible_trait>
782 class _LIBCPP_TEMPLATE_VIS __move_constructor;
784 #define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, \
786 template <class... _Types> \
787 class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>, \
788 move_constructible_trait> \
789 : public __constructor<__traits<_Types...>> { \
790 using __base_type = __constructor<__traits<_Types...>>; \
793 using __base_type::__base_type; \
794 using __base_type::operator=; \
796 __move_constructor(const __move_constructor&) = default; \
798 ~__move_constructor() = default; \
799 __move_constructor& operator=(const __move_constructor&) = default; \
800 __move_constructor& operator=(__move_constructor&&) = default; \
803 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
804 _Trait::_TriviallyAvailable,
805 __move_constructor(__move_constructor&& __that) = default;);
807 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
809 __move_constructor(__move_constructor&& __that) noexcept(
810 __all<is_nothrow_move_constructible_v<_Types>...>::value)
811 : __move_constructor(__valueless_t{}) {
812 this->__generic_construct(*this, _VSTD::move(__that));
815 _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
816 _Trait::_Unavailable,
817 __move_constructor(__move_constructor&&) = delete;);
819 #undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR
821 template <class _Traits, _Trait = _Traits::__copy_constructible_trait>
822 class _LIBCPP_TEMPLATE_VIS __copy_constructor;
824 #define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, \
826 template <class... _Types> \
827 class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, \
828 copy_constructible_trait> \
829 : public __move_constructor<__traits<_Types...>> { \
830 using __base_type = __move_constructor<__traits<_Types...>>; \
833 using __base_type::__base_type; \
834 using __base_type::operator=; \
837 __copy_constructor(__copy_constructor&&) = default; \
838 ~__copy_constructor() = default; \
839 __copy_constructor& operator=(const __copy_constructor&) = default; \
840 __copy_constructor& operator=(__copy_constructor&&) = default; \
843 _LIBCPP_VARIANT_COPY_CONSTRUCTOR(
844 _Trait::_TriviallyAvailable,
845 __copy_constructor(const __copy_constructor& __that) = default;);
847 _LIBCPP_VARIANT_COPY_CONSTRUCTOR(
849 __copy_constructor(const __copy_constructor& __that)
850 : __copy_constructor(__valueless_t{}) {
851 this->__generic_construct(*this, __that);
854 _LIBCPP_VARIANT_COPY_CONSTRUCTOR(
855 _Trait::_Unavailable,
856 __copy_constructor(const __copy_constructor&) = delete;);
858 #undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR
860 template <class _Traits>
861 class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> {
862 using __base_type = __copy_constructor<_Traits>;
865 using __base_type::__base_type;
866 using __base_type::operator=;
868 template <size_t _Ip, class... _Args>
869 inline _LIBCPP_INLINE_VISIBILITY
870 auto& __emplace(_Args&&... __args) {
872 auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this),
873 _VSTD::forward<_Args>(__args)...);
879 template <size_t _Ip, class _Tp, class _Arg>
880 inline _LIBCPP_INLINE_VISIBILITY
881 void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) {
882 if (this->index() == _Ip) {
883 __a.__value = _VSTD::forward<_Arg>(__arg);
886 void operator()(true_type) const {
887 __this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg));
889 void operator()(false_type) const {
890 __this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg)));
892 __assignment* __this;
894 } __impl{this, _VSTD::forward<_Arg>(__arg)};
895 __impl(bool_constant<is_nothrow_constructible_v<_Tp, _Arg> ||
896 !is_nothrow_move_constructible_v<_Tp>>{});
900 template <class _That>
901 inline _LIBCPP_INLINE_VISIBILITY
902 void __generic_assign(_That&& __that) {
903 if (this->valueless_by_exception() && __that.valueless_by_exception()) {
905 } else if (__that.valueless_by_exception()) {
908 __visitation::__base::__visit_alt_at(
910 [this](auto& __this_alt, auto&& __that_alt) {
913 _VSTD::forward<decltype(__that_alt)>(__that_alt).__value);
915 *this, _VSTD::forward<_That>(__that));
920 template <class _Traits, _Trait = _Traits::__move_assignable_trait>
921 class _LIBCPP_TEMPLATE_VIS __move_assignment;
923 #define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, \
925 template <class... _Types> \
926 class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, \
927 move_assignable_trait> \
928 : public __assignment<__traits<_Types...>> { \
929 using __base_type = __assignment<__traits<_Types...>>; \
932 using __base_type::__base_type; \
933 using __base_type::operator=; \
935 __move_assignment(const __move_assignment&) = default; \
936 __move_assignment(__move_assignment&&) = default; \
937 ~__move_assignment() = default; \
938 __move_assignment& operator=(const __move_assignment&) = default; \
942 _LIBCPP_VARIANT_MOVE_ASSIGNMENT(
943 _Trait::_TriviallyAvailable,
944 __move_assignment& operator=(__move_assignment&& __that) = default;);
946 _LIBCPP_VARIANT_MOVE_ASSIGNMENT(
948 __move_assignment& operator=(__move_assignment&& __that) noexcept(
949 __all<(is_nothrow_move_constructible_v<_Types> &&
950 is_nothrow_move_assignable_v<_Types>)...>::value) {
951 this->__generic_assign(_VSTD::move(__that));
955 _LIBCPP_VARIANT_MOVE_ASSIGNMENT(
956 _Trait::_Unavailable,
957 __move_assignment& operator=(__move_assignment&&) = delete;);
959 #undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT
961 template <class _Traits, _Trait = _Traits::__copy_assignable_trait>
962 class _LIBCPP_TEMPLATE_VIS __copy_assignment;
964 #define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, \
966 template <class... _Types> \
967 class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, \
968 copy_assignable_trait> \
969 : public __move_assignment<__traits<_Types...>> { \
970 using __base_type = __move_assignment<__traits<_Types...>>; \
973 using __base_type::__base_type; \
974 using __base_type::operator=; \
976 __copy_assignment(const __copy_assignment&) = default; \
977 __copy_assignment(__copy_assignment&&) = default; \
978 ~__copy_assignment() = default; \
980 __copy_assignment& operator=(__copy_assignment&&) = default; \
983 _LIBCPP_VARIANT_COPY_ASSIGNMENT(
984 _Trait::_TriviallyAvailable,
985 __copy_assignment& operator=(const __copy_assignment& __that) = default;);
987 _LIBCPP_VARIANT_COPY_ASSIGNMENT(
989 __copy_assignment& operator=(const __copy_assignment& __that) {
990 this->__generic_assign(__that);
994 _LIBCPP_VARIANT_COPY_ASSIGNMENT(
995 _Trait::_Unavailable,
996 __copy_assignment& operator=(const __copy_assignment&) = delete;);
998 #undef _LIBCPP_VARIANT_COPY_ASSIGNMENT
1000 template <class... _Types>
1001 class _LIBCPP_TEMPLATE_VIS __impl
1002 : public __copy_assignment<__traits<_Types...>> {
1003 using __base_type = __copy_assignment<__traits<_Types...>>;
1006 using __base_type::__base_type;
1007 using __base_type::operator=;
1009 template <size_t _Ip, class _Arg>
1010 inline _LIBCPP_INLINE_VISIBILITY
1011 void __assign(_Arg&& __arg) {
1012 this->__assign_alt(__access::__base::__get_alt<_Ip>(*this),
1013 _VSTD::forward<_Arg>(__arg));
1016 inline _LIBCPP_INLINE_VISIBILITY
1017 void __swap(__impl& __that) {
1018 if (this->valueless_by_exception() && __that.valueless_by_exception()) {
1020 } else if (this->index() == __that.index()) {
1021 __visitation::__base::__visit_alt_at(
1023 [](auto& __this_alt, auto& __that_alt) {
1025 swap(__this_alt.__value, __that_alt.__value);
1030 __impl* __lhs = this;
1031 __impl* __rhs = _VSTD::addressof(__that);
1032 if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) {
1033 _VSTD::swap(__lhs, __rhs);
1035 __impl __tmp(_VSTD::move(*__rhs));
1036 #ifndef _LIBCPP_NO_EXCEPTIONS
1037 // EXTENSION: When the move construction of `__lhs` into `__rhs` throws
1038 // and `__tmp` is nothrow move constructible then we move `__tmp` back
1039 // into `__rhs` and provide the strong exception safety guarentee.
1041 this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
1043 if (__tmp.__move_nothrow()) {
1044 this->__generic_construct(*__rhs, _VSTD::move(__tmp));
1049 this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
1051 this->__generic_construct(*__lhs, _VSTD::move(__tmp));
1056 inline _LIBCPP_INLINE_VISIBILITY
1057 bool __move_nothrow() const {
1058 constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...};
1059 return this->valueless_by_exception() || __results[this->index()];
1063 template <class... _Types>
1067 struct __overload<> { void operator()() const; };
1069 template <class _Tp, class... _Types>
1070 struct __overload<_Tp, _Types...> : __overload<_Types...> {
1071 using __overload<_Types...>::operator();
1072 __identity<_Tp> operator()(_Tp) const;
1075 template <class _Tp, class... _Types>
1076 using __best_match_t = typename result_of_t<__overload<_Types...>(_Tp&&)>::type;
1078 } // __variant_detail
1080 template <class... _Types>
1081 class _LIBCPP_TEMPLATE_VIS variant
1082 : private __sfinae_ctor_base<
1083 __all<is_copy_constructible_v<_Types>...>::value,
1084 __all<is_move_constructible_v<_Types>...>::value>,
1085 private __sfinae_assign_base<
1086 __all<(is_copy_constructible_v<_Types> &&
1087 is_copy_assignable_v<_Types>)...>::value,
1088 __all<(is_move_constructible_v<_Types> &&
1089 is_move_assignable_v<_Types>)...>::value> {
1090 static_assert(0 < sizeof...(_Types),
1091 "variant must consist of at least one alternative.");
1093 static_assert(__all<!is_array_v<_Types>...>::value,
1094 "variant can not have an array type as an alternative.");
1096 static_assert(__all<!is_reference_v<_Types>...>::value,
1097 "variant can not have a reference type as an alternative.");
1099 static_assert(__all<!is_void_v<_Types>...>::value,
1100 "variant can not have a void type as an alternative.");
1102 using __first_type = variant_alternative_t<0, variant>;
1105 template <bool _Dummy = true,
1106 enable_if_t<__dependent_type<is_default_constructible<__first_type>,
1109 inline _LIBCPP_INLINE_VISIBILITY
1110 constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>)
1111 : __impl(in_place_index<0>) {}
1113 variant(const variant&) = default;
1114 variant(variant&&) = default;
1118 enable_if_t<!is_same_v<decay_t<_Arg>, variant>, int> = 0,
1119 enable_if_t<!__is_inplace_type<decay_t<_Arg>>::value, int> = 0,
1120 enable_if_t<!__is_inplace_index<decay_t<_Arg>>::value, int> = 0,
1121 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
1123 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1124 enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0>
1125 inline _LIBCPP_INLINE_VISIBILITY
1126 constexpr variant(_Arg&& __arg) noexcept(
1127 is_nothrow_constructible_v<_Tp, _Arg>)
1128 : __impl(in_place_index<_Ip>, _VSTD::forward<_Arg>(__arg)) {}
1130 template <size_t _Ip, class... _Args,
1131 class = enable_if_t<(_Ip < sizeof...(_Types)), int>,
1132 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1133 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1134 inline _LIBCPP_INLINE_VISIBILITY
1135 explicit constexpr variant(
1136 in_place_index_t<_Ip>,
1137 _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>)
1138 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {}
1144 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
1145 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1146 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1148 inline _LIBCPP_INLINE_VISIBILITY
1149 explicit constexpr variant(
1150 in_place_index_t<_Ip>,
1151 initializer_list<_Up> __il,
1152 _Args&&... __args) noexcept(
1153 is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>)
1154 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {}
1160 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1161 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1162 inline _LIBCPP_INLINE_VISIBILITY
1163 explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept(
1164 is_nothrow_constructible_v<_Tp, _Args...>)
1165 : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {}
1172 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1173 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1175 inline _LIBCPP_INLINE_VISIBILITY
1176 explicit constexpr variant(
1177 in_place_type_t<_Tp>,
1178 initializer_list<_Up> __il,
1179 _Args&&... __args) noexcept(
1180 is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>)
1181 : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {}
1183 ~variant() = default;
1185 variant& operator=(const variant&) = default;
1186 variant& operator=(variant&&) = default;
1190 enable_if_t<!is_same_v<decay_t<_Arg>, variant>, int> = 0,
1191 class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
1193 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1194 enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>,
1196 inline _LIBCPP_INLINE_VISIBILITY
1197 variant& operator=(_Arg&& __arg) noexcept(
1198 is_nothrow_assignable_v<_Tp&, _Arg> &&
1199 is_nothrow_constructible_v<_Tp, _Arg>) {
1200 __impl.template __assign<_Ip>(_VSTD::forward<_Arg>(__arg));
1207 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
1208 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1209 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1210 inline _LIBCPP_INLINE_VISIBILITY
1211 _Tp& emplace(_Args&&... __args) {
1212 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...);
1219 enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
1220 class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
1221 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1223 inline _LIBCPP_INLINE_VISIBILITY
1224 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
1225 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...);
1232 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1233 enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
1234 inline _LIBCPP_INLINE_VISIBILITY
1235 _Tp& emplace(_Args&&... __args) {
1236 return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...);
1244 __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
1245 enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
1247 inline _LIBCPP_INLINE_VISIBILITY
1248 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
1249 return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...);
1252 inline _LIBCPP_INLINE_VISIBILITY
1253 constexpr bool valueless_by_exception() const noexcept {
1254 return __impl.valueless_by_exception();
1257 inline _LIBCPP_INLINE_VISIBILITY
1258 constexpr size_t index() const noexcept { return __impl.index(); }
1264 __dependent_type<is_move_constructible<_Types>, _Dummy>::value &&
1265 __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value,
1267 inline _LIBCPP_INLINE_VISIBILITY
1268 void swap(variant& __that) noexcept(
1269 __all<(is_nothrow_move_constructible_v<_Types> &&
1270 is_nothrow_swappable_v<_Types>)...>::value) {
1271 __impl.__swap(__that.__impl);
1275 __variant_detail::__impl<_Types...> __impl;
1277 friend struct __variant_detail::__access::__variant;
1278 friend struct __variant_detail::__visitation::__variant;
1281 template <size_t _Ip, class... _Types>
1282 inline _LIBCPP_INLINE_VISIBILITY
1283 constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept {
1284 return __v.index() == _Ip;
1287 template <class _Tp, class... _Types>
1288 inline _LIBCPP_INLINE_VISIBILITY
1289 constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept {
1290 return __holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1293 template <size_t _Ip, class _Vp>
1294 inline _LIBCPP_INLINE_VISIBILITY
1295 static constexpr auto&& __generic_get(_Vp&& __v) {
1296 using __variant_detail::__access::__variant;
1297 if (!__holds_alternative<_Ip>(__v)) {
1298 __throw_bad_variant_access();
1300 return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value;
1303 template <size_t _Ip, class... _Types>
1304 inline _LIBCPP_INLINE_VISIBILITY
1305 constexpr variant_alternative_t<_Ip, variant<_Types...>>& get(
1306 variant<_Types...>& __v) {
1307 static_assert(_Ip < sizeof...(_Types));
1308 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1309 return __generic_get<_Ip>(__v);
1312 template <size_t _Ip, class... _Types>
1313 inline _LIBCPP_INLINE_VISIBILITY
1314 constexpr variant_alternative_t<_Ip, variant<_Types...>>&& get(
1315 variant<_Types...>&& __v) {
1316 static_assert(_Ip < sizeof...(_Types));
1317 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1318 return __generic_get<_Ip>(_VSTD::move(__v));
1321 template <size_t _Ip, class... _Types>
1322 inline _LIBCPP_INLINE_VISIBILITY
1323 constexpr const variant_alternative_t<_Ip, variant<_Types...>>& get(
1324 const variant<_Types...>& __v) {
1325 static_assert(_Ip < sizeof...(_Types));
1326 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1327 return __generic_get<_Ip>(__v);
1330 template <size_t _Ip, class... _Types>
1331 inline _LIBCPP_INLINE_VISIBILITY
1332 constexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get(
1333 const variant<_Types...>&& __v) {
1334 static_assert(_Ip < sizeof...(_Types));
1335 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1336 return __generic_get<_Ip>(_VSTD::move(__v));
1339 template <class _Tp, class... _Types>
1340 inline _LIBCPP_INLINE_VISIBILITY
1341 constexpr _Tp& get(variant<_Types...>& __v) {
1342 static_assert(!is_void_v<_Tp>);
1343 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1346 template <class _Tp, class... _Types>
1347 inline _LIBCPP_INLINE_VISIBILITY
1348 constexpr _Tp&& get(variant<_Types...>&& __v) {
1349 static_assert(!is_void_v<_Tp>);
1350 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(
1354 template <class _Tp, class... _Types>
1355 inline _LIBCPP_INLINE_VISIBILITY
1356 constexpr const _Tp& get(const variant<_Types...>& __v) {
1357 static_assert(!is_void_v<_Tp>);
1358 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1361 template <class _Tp, class... _Types>
1362 inline _LIBCPP_INLINE_VISIBILITY
1363 constexpr const _Tp&& get(const variant<_Types...>&& __v) {
1364 static_assert(!is_void_v<_Tp>);
1365 return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(
1369 template <size_t _Ip, class _Vp>
1370 inline _LIBCPP_INLINE_VISIBILITY
1371 constexpr auto* __generic_get_if(_Vp* __v) noexcept {
1372 using __variant_detail::__access::__variant;
1373 return __v && __holds_alternative<_Ip>(*__v)
1374 ? _VSTD::addressof(__variant::__get_alt<_Ip>(*__v).__value)
1378 template <size_t _Ip, class... _Types>
1379 inline _LIBCPP_INLINE_VISIBILITY
1380 constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>>
1381 get_if(variant<_Types...>* __v) noexcept {
1382 static_assert(_Ip < sizeof...(_Types));
1383 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1384 return __generic_get_if<_Ip>(__v);
1387 template <size_t _Ip, class... _Types>
1388 inline _LIBCPP_INLINE_VISIBILITY
1389 constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>>
1390 get_if(const variant<_Types...>* __v) noexcept {
1391 static_assert(_Ip < sizeof...(_Types));
1392 static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
1393 return __generic_get_if<_Ip>(__v);
1396 template <class _Tp, class... _Types>
1397 inline _LIBCPP_INLINE_VISIBILITY
1398 constexpr add_pointer_t<_Tp>
1399 get_if(variant<_Types...>* __v) noexcept {
1400 static_assert(!is_void_v<_Tp>);
1401 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1404 template <class _Tp, class... _Types>
1405 inline _LIBCPP_INLINE_VISIBILITY
1406 constexpr add_pointer_t<const _Tp>
1407 get_if(const variant<_Types...>* __v) noexcept {
1408 static_assert(!is_void_v<_Tp>);
1409 return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1412 template <class... _Types>
1413 inline _LIBCPP_INLINE_VISIBILITY
1414 constexpr bool operator==(const variant<_Types...>& __lhs,
1415 const variant<_Types...>& __rhs) {
1416 using __variant_detail::__visitation::__variant;
1417 if (__lhs.index() != __rhs.index()) return false;
1418 if (__lhs.valueless_by_exception()) return true;
1419 return __variant::__visit_value_at(__lhs.index(), equal_to<>{}, __lhs, __rhs);
1422 template <class... _Types>
1423 inline _LIBCPP_INLINE_VISIBILITY
1424 constexpr bool operator!=(const variant<_Types...>& __lhs,
1425 const variant<_Types...>& __rhs) {
1426 using __variant_detail::__visitation::__variant;
1427 if (__lhs.index() != __rhs.index()) return true;
1428 if (__lhs.valueless_by_exception()) return false;
1429 return __variant::__visit_value_at(
1430 __lhs.index(), not_equal_to<>{}, __lhs, __rhs);
1433 template <class... _Types>
1434 inline _LIBCPP_INLINE_VISIBILITY
1435 constexpr bool operator<(const variant<_Types...>& __lhs,
1436 const variant<_Types...>& __rhs) {
1437 using __variant_detail::__visitation::__variant;
1438 if (__rhs.valueless_by_exception()) return false;
1439 if (__lhs.valueless_by_exception()) return true;
1440 if (__lhs.index() < __rhs.index()) return true;
1441 if (__lhs.index() > __rhs.index()) return false;
1442 return __variant::__visit_value_at(__lhs.index(), less<>{}, __lhs, __rhs);
1445 template <class... _Types>
1446 inline _LIBCPP_INLINE_VISIBILITY
1447 constexpr bool operator>(const variant<_Types...>& __lhs,
1448 const variant<_Types...>& __rhs) {
1449 using __variant_detail::__visitation::__variant;
1450 if (__lhs.valueless_by_exception()) return false;
1451 if (__rhs.valueless_by_exception()) return true;
1452 if (__lhs.index() > __rhs.index()) return true;
1453 if (__lhs.index() < __rhs.index()) return false;
1454 return __variant::__visit_value_at(__lhs.index(), greater<>{}, __lhs, __rhs);
1457 template <class... _Types>
1458 inline _LIBCPP_INLINE_VISIBILITY
1459 constexpr bool operator<=(const variant<_Types...>& __lhs,
1460 const variant<_Types...>& __rhs) {
1461 using __variant_detail::__visitation::__variant;
1462 if (__lhs.valueless_by_exception()) return true;
1463 if (__rhs.valueless_by_exception()) return false;
1464 if (__lhs.index() < __rhs.index()) return true;
1465 if (__lhs.index() > __rhs.index()) return false;
1466 return __variant::__visit_value_at(
1467 __lhs.index(), less_equal<>{}, __lhs, __rhs);
1470 template <class... _Types>
1471 inline _LIBCPP_INLINE_VISIBILITY
1472 constexpr bool operator>=(const variant<_Types...>& __lhs,
1473 const variant<_Types...>& __rhs) {
1474 using __variant_detail::__visitation::__variant;
1475 if (__rhs.valueless_by_exception()) return true;
1476 if (__lhs.valueless_by_exception()) return false;
1477 if (__lhs.index() > __rhs.index()) return true;
1478 if (__lhs.index() < __rhs.index()) return false;
1479 return __variant::__visit_value_at(
1480 __lhs.index(), greater_equal<>{}, __lhs, __rhs);
1483 template <class _Visitor, class... _Vs>
1484 inline _LIBCPP_INLINE_VISIBILITY
1485 constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) {
1486 using __variant_detail::__visitation::__variant;
1487 bool __results[] = {__vs.valueless_by_exception()...};
1488 for (bool __result : __results) {
1490 __throw_bad_variant_access();
1493 return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor),
1494 _VSTD::forward<_Vs>(__vs)...);
1497 struct _LIBCPP_TEMPLATE_VIS monostate {};
1499 inline _LIBCPP_INLINE_VISIBILITY
1500 constexpr bool operator<(monostate, monostate) noexcept { return false; }
1502 inline _LIBCPP_INLINE_VISIBILITY
1503 constexpr bool operator>(monostate, monostate) noexcept { return false; }
1505 inline _LIBCPP_INLINE_VISIBILITY
1506 constexpr bool operator<=(monostate, monostate) noexcept { return true; }
1508 inline _LIBCPP_INLINE_VISIBILITY
1509 constexpr bool operator>=(monostate, monostate) noexcept { return true; }
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 false; }
1517 template <class... _Types>
1518 inline _LIBCPP_INLINE_VISIBILITY
1519 auto swap(variant<_Types...>& __lhs,
1520 variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs)))
1521 -> decltype(__lhs.swap(__rhs)) {
1525 template <class... _Types>
1526 struct _LIBCPP_TEMPLATE_VIS hash<
1527 __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> {
1528 using argument_type = variant<_Types...>;
1529 using result_type = size_t;
1531 inline _LIBCPP_INLINE_VISIBILITY
1532 result_type operator()(const argument_type& __v) const {
1533 using __variant_detail::__visitation::__variant;
1535 __v.valueless_by_exception()
1536 ? 299792458 // Random value chosen by the universe upon creation
1537 : __variant::__visit_alt(
1538 [](const auto& __alt) {
1539 using __alt_type = decay_t<decltype(__alt)>;
1540 using __value_type = remove_const_t<
1541 typename __alt_type::__value_type>;
1542 return hash<__value_type>{}(__alt.__value);
1545 return __hash_combine(__res, hash<size_t>{}(__v.index()));
1550 struct _LIBCPP_TEMPLATE_VIS hash<monostate> {
1551 using argument_type = monostate;
1552 using result_type = size_t;
1554 inline _LIBCPP_INLINE_VISIBILITY
1555 result_type operator()(const argument_type&) const _NOEXCEPT {
1556 return 66740831; // return a fundamentally attractive random value.
1560 #endif // _LIBCPP_STD_VER > 14
1562 _LIBCPP_END_NAMESPACE_STD
1564 #endif // _LIBCPP_VARIANT