// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP_VARIANT
#define _LIBCPP_VARIANT
/*
variant synopsis
namespace std {
// 20.7.2, class template variant
template <class... Types>
class variant {
public:
// 20.7.2.1, constructors
constexpr variant() noexcept(see below);
constexpr variant(const variant&);
constexpr variant(variant&&) noexcept(see below);
template <class T> constexpr variant(T&&) noexcept(see below);
template <class T, class... Args>
constexpr explicit variant(in_place_type_t<T>, Args&&...);
template <class T, class U, class... Args>
constexpr explicit variant(
in_place_type_t<T>, initializer_list<U>, Args&&...);
template <size_t I, class... Args>
constexpr explicit variant(in_place_index_t<I>, Args&&...);
template <size_t I, class U, class... Args>
constexpr explicit variant(
in_place_index_t<I>, initializer_list<U>, Args&&...);
// 20.7.2.2, destructor
constexpr ~variant(); // constexpr since c++20
// 20.7.2.3, assignment
constexpr variant& operator=(const variant&);
constexpr variant& operator=(variant&&) noexcept(see below);
template <class T>
constexpr variant& operator=(T&&) noexcept(see below); // constexpr since c++20
// 20.7.2.4, modifiers
template <class T, class... Args>
constexpr T& emplace(Args&&...); // constexpr since c++20
template <class T, class U, class... Args>
constexpr T& emplace(initializer_list<U>, Args&&...); // constexpr since c++20
template <size_t I, class... Args>
constexpr variant_alternative_t<I, variant>& emplace(Args&&...); // constexpr since c++20
template <size_t I, class U, class... Args>
constexpr variant_alternative_t<I, variant>&
emplace(initializer_list<U>, Args&&...); // constexpr since c++20
// 20.7.2.5, value status
constexpr bool valueless_by_exception() const noexcept;
constexpr size_t index() const noexcept;
// 20.7.2.6, swap
void swap(variant&) noexcept(see below);
// [variant.visit], visitation
template<class Self, class Visitor>
constexpr decltype(auto) visit(this Self&&, Visitor&&); // Since C++26
template<class R, class Self, class Visitor>
constexpr R visit(this Self&&, Visitor&&); // Since C++26
};
// 20.7.3, variant helper classes
template <class T> struct variant_size; // undefined
template <class T>
inline constexpr size_t variant_size_v = variant_size<T>::value;
template <class T> struct variant_size<const T>;
template <class T> struct variant_size<volatile T>;
template <class T> struct variant_size<const volatile T>;
template <class... Types>
struct variant_size<variant<Types...>>;
template <size_t I, class T> struct variant_alternative; // undefined
template <size_t I, class T>
using variant_alternative_t = typename variant_alternative<I, T>::type;
template <size_t I, class T> struct variant_alternative<I, const T>;
template <size_t I, class T> struct variant_alternative<I, volatile T>;
template <size_t I, class T> struct variant_alternative<I, const volatile T>;
template <size_t I, class... Types>
struct variant_alternative<I, variant<Types...>>;
inline constexpr size_t variant_npos = -1;
// 20.7.4, value access
template <class T, class... Types>
constexpr bool holds_alternative(const variant<Types...>&) noexcept;
template <size_t I, class... Types>
constexpr variant_alternative_t<I, variant<Types...>>&
get(variant<Types...>&);
template <size_t I, class... Types>
constexpr variant_alternative_t<I, variant<Types...>>&&
get(variant<Types...>&&);
template <size_t I, class... Types>
constexpr variant_alternative_t<I, variant<Types...>> const&
get(const variant<Types...>&);
template <size_t I, class... Types>
constexpr variant_alternative_t<I, variant<Types...>> const&&
get(const variant<Types...>&&);
template <class T, class... Types>
constexpr T& get(variant<Types...>&);
template <class T, class... Types>
constexpr T&& get(variant<Types...>&&);
template <class T, class... Types>
constexpr const T& get(const variant<Types...>&);
template <class T, class... Types>
constexpr const T&& get(const variant<Types...>&&);
template <size_t I, class... Types>
constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>>
get_if(variant<Types...>*) noexcept;
template <size_t I, class... Types>
constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>>
get_if(const variant<Types...>*) noexcept;
template <class T, class... Types>
constexpr add_pointer_t<T>
get_if(variant<Types...>*) noexcept;
template <class T, class... Types>
constexpr add_pointer_t<const T>
get_if(const variant<Types...>*) noexcept;
// 20.7.5, relational operators
template <class... Types>
constexpr bool operator==(const variant<Types...>&, const variant<Types...>&);
template <class... Types>
constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&);
template <class... Types>
constexpr bool operator<(const variant<Types...>&, const variant<Types...>&);
template <class... Types>
constexpr bool operator>(const variant<Types...>&, const variant<Types...>&);
template <class... Types>
constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&);
template <class... Types>
constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&);
template <class... Types> requires (three_way_comparable<Types> && ...)
constexpr common_comparison_category_t<compare_three_way_result_t<Types>...>
operator<=>(const variant<Types...>&, const variant<Types...>&); // since C++20
// 20.7.6, visitation
template <class Visitor, class... Variants>
constexpr see below visit(Visitor&&, Variants&&...);
template <class R, class Visitor, class... Variants>
constexpr R visit(Visitor&&, Variants&&...); // since C++20
// 20.7.7, class monostate
struct monostate;
// 20.7.8, monostate relational operators
constexpr bool operator==(monostate, monostate) noexcept;
constexpr bool operator!=(monostate, monostate) noexcept; // until C++20
constexpr bool operator<(monostate, monostate) noexcept; // until C++20
constexpr bool operator>(monostate, monostate) noexcept; // until C++20
constexpr bool operator<=(monostate, monostate) noexcept; // until C++20
constexpr bool operator>=(monostate, monostate) noexcept; // until C++20
constexpr strong_ordering operator<=>(monostate, monostate) noexcept; // since C++20
// 20.7.9, specialized algorithms
template <class... Types>
void swap(variant<Types...>&, variant<Types...>&) noexcept(see below);
// 20.7.10, class bad_variant_access
class bad_variant_access;
// 20.7.11, hash support
template <class T> struct hash;
template <class... Types> struct hash<variant<Types...>>;
template <> struct hash<monostate>;
} // namespace std
*/
#include <__compare/common_comparison_category.h>
#include <__compare/compare_three_way_result.h>
#include <__compare/ordering.h>
#include <__compare/three_way_comparable.h>
#include <__config>
#include <__exception/exception.h>
#include <__functional/hash.h>
#include <__functional/operations.h>
#include <__functional/unary_function.h>
#include <__fwd/variant.h>
#include <__memory/addressof.h>
#include <__memory/construct_at.h>
#include <__tuple/find_index.h>
#include <__tuple/sfinae_helpers.h>
#include <__type_traits/add_const.h>
#include <__type_traits/add_cv.h>
#include <__type_traits/add_pointer.h>
#include <__type_traits/add_volatile.h>
#include <__type_traits/common_type.h>
#include <__type_traits/conditional.h>
#include <__type_traits/conjunction.h>
#include <__type_traits/decay.h>
#include <__type_traits/dependent_type.h>
#include <__type_traits/enable_if.h>
#include <__type_traits/invoke.h>
#include <__type_traits/is_array.h>
#include <__type_traits/is_assignable.h>
#include <__type_traits/is_constructible.h>
#include <__type_traits/is_convertible.h>
#include <__type_traits/is_destructible.h>
#include <__type_traits/is_nothrow_assignable.h>
#include <__type_traits/is_nothrow_constructible.h>
#include <__type_traits/is_reference.h>
#include <__type_traits/is_swappable.h>
#include <__type_traits/is_trivially_assignable.h>
#include <__type_traits/is_trivially_constructible.h>
#include <__type_traits/is_trivially_destructible.h>
#include <__type_traits/is_trivially_relocatable.h>
#include <__type_traits/is_void.h>
#include <__type_traits/remove_const.h>
#include <__type_traits/remove_cvref.h>
#include <__type_traits/remove_reference.h>
#include <__type_traits/type_identity.h>
#include <__type_traits/void_t.h>
#include <__utility/declval.h>
#include <__utility/forward.h>
#include <__utility/forward_like.h>
#include <__utility/in_place.h>
#include <__utility/integer_sequence.h>
#include <__utility/move.h>
#include <__utility/swap.h>
#include <__variant/monostate.h>
#include <__verbose_abort>
#include <initializer_list>
#include <limits>
#include <new>
#include <version>
// standard-mandated includes
// [variant.syn]
#include <compare>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
namespace std { // explicitly not using versioning namespace
class _LIBCPP_EXPORTED_FROM_ABI _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS bad_variant_access : public exception {
public:
const char* what() const _NOEXCEPT override;
};
} // namespace std
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER >= 17
// Light N-dimensional array of function pointers. Used in place of std::array to avoid
// adding a dependency.
template <class _Tp, size_t _Size>
struct __farray {
static_assert(_Size > 0, "N-dimensional array should never be empty in std::visit");
_Tp __buf_[_Size] = {};
_LIBCPP_HIDE_FROM_ABI constexpr const _Tp& operator[](size_t __n) const noexcept { return __buf_[__n]; }
};
[[noreturn]] inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS void
__throw_bad_variant_access() {
# ifndef _LIBCPP_HAS_NO_EXCEPTIONS
throw bad_variant_access();
# else
_LIBCPP_VERBOSE_ABORT("bad_variant_access was thrown in -fno-exceptions mode");
# endif
}
// variant_size
template <class _Tp>
struct _LIBCPP_TEMPLATE_VIS variant_size<const _Tp> : variant_size<_Tp> {};
template <class _Tp>
struct _LIBCPP_TEMPLATE_VIS variant_size<volatile _Tp> : variant_size<_Tp> {};
template <class _Tp>
struct _LIBCPP_TEMPLATE_VIS variant_size<const volatile _Tp> : variant_size<_Tp> {};
template <class... _Types>
struct _LIBCPP_TEMPLATE_VIS variant_size<variant<_Types...>> : integral_constant<size_t, sizeof...(_Types)> {};
// variant_alternative
template <size_t _Ip, class _Tp>
struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const _Tp> : add_const<variant_alternative_t<_Ip, _Tp>> {};
template <size_t _Ip, class _Tp>
struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, volatile _Tp> : add_volatile<variant_alternative_t<_Ip, _Tp>> {};
template <size_t _Ip, class _Tp>
struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const volatile _Tp> : add_cv<variant_alternative_t<_Ip, _Tp>> {};
template <size_t _Ip, class... _Types>
struct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, variant<_Types...>> {
static_assert(_Ip < sizeof...(_Types), "Index out of bounds in std::variant_alternative<>");
using type = __type_pack_element<_Ip, _Types...>;
};
template <size_t _NumAlternatives>
_LIBCPP_HIDE_FROM_ABI constexpr auto __choose_index_type() {
# ifdef _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION
if constexpr (_NumAlternatives < numeric_limits<unsigned char>::max())
return static_cast<unsigned char>(0);
else if constexpr (_NumAlternatives < numeric_limits<unsigned short>::max())
return static_cast<unsigned short>(0);
else
# endif // _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION
return static_cast<unsigned int>(0);
}
template <size_t _NumAlts>
using __variant_index_t = decltype(std::__choose_index_type<_NumAlts>());
template <class _IndexType>
constexpr _IndexType __variant_npos = static_cast<_IndexType>(-1);
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr variant<_Types...>& __as_variant(variant<_Types...>& __vs) noexcept {
return __vs;
}
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr const variant<_Types...>& __as_variant(const variant<_Types...>& __vs) noexcept {
return __vs;
}
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr variant<_Types...>&& __as_variant(variant<_Types...>&& __vs) noexcept {
return std::move(__vs);
}
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr const variant<_Types...>&& __as_variant(const variant<_Types...>&& __vs) noexcept {
return std::move(__vs);
}
namespace __find_detail {
template <class _Tp, class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr size_t __find_index() {
constexpr bool __matches[] = {is_same_v<_Tp, _Types>...};
size_t __result = __not_found;
for (size_t __i = 0; __i < sizeof...(_Types); ++__i) {
if (__matches[__i]) {
if (__result != __not_found) {
return __ambiguous;
}
__result = __i;
}
}
return __result;
}
template <size_t _Index>
struct __find_unambiguous_index_sfinae_impl : integral_constant<size_t, _Index> {};
template <>
struct __find_unambiguous_index_sfinae_impl<__not_found> {};
template <>
struct __find_unambiguous_index_sfinae_impl<__ambiguous> {};
template <class _Tp, class... _Types>
struct __find_unambiguous_index_sfinae : __find_unambiguous_index_sfinae_impl<__find_index<_Tp, _Types...>()> {};
} // namespace __find_detail
namespace __variant_detail {
struct __valueless_t {};
enum class _Trait { _TriviallyAvailable, _Available, _Unavailable };
template <typename _Tp, template <typename> class _IsTriviallyAvailable, template <typename> class _IsAvailable>
constexpr _Trait __trait =
_IsTriviallyAvailable<_Tp>::value ? _Trait::_TriviallyAvailable
: _IsAvailable<_Tp>::value
? _Trait::_Available
: _Trait::_Unavailable;
_LIBCPP_HIDE_FROM_ABI constexpr _Trait __common_trait(initializer_list<_Trait> __traits) {
_Trait __result = _Trait::_TriviallyAvailable;
for (_Trait __t : __traits) {
if (static_cast<int>(__t) > static_cast<int>(__result)) {
__result = __t;
}
}
return __result;
}
template <typename... _Types>
struct __traits {
static constexpr _Trait __copy_constructible_trait =
__variant_detail::__common_trait({__trait<_Types, is_trivially_copy_constructible, is_copy_constructible>...});
static constexpr _Trait __move_constructible_trait =
__variant_detail::__common_trait({__trait<_Types, is_trivially_move_constructible, is_move_constructible>...});
static constexpr _Trait __copy_assignable_trait = __variant_detail::__common_trait(
{__copy_constructible_trait, __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...});
static constexpr _Trait __move_assignable_trait = __variant_detail::__common_trait(
{__move_constructible_trait, __trait<_Types, is_trivially_move_assignable, is_move_assignable>...});
static constexpr _Trait __destructible_trait =
__variant_detail::__common_trait({__trait<_Types, is_trivially_destructible, is_destructible>...});
};
namespace __access {
struct __union {
template <class _Vp>
_LIBCPP_HIDE_FROM_ABI static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) {
return std::forward<_Vp>(__v).__head;
}
template <class _Vp, size_t _Ip>
_LIBCPP_HIDE_FROM_ABI static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) {
return __get_alt(std::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>);
}
};
struct __base {
template <size_t _Ip, class _Vp>
_LIBCPP_HIDE_FROM_ABI static constexpr auto&& __get_alt(_Vp&& __v) {
return __union::__get_alt(std::forward<_Vp>(__v).__data, in_place_index<_Ip>);
}
};
struct __variant {
template <size_t _Ip, class _Vp>
_LIBCPP_HIDE_FROM_ABI static constexpr auto&& __get_alt(_Vp&& __v) {
return __base::__get_alt<_Ip>(std::forward<_Vp>(__v).__impl_);
}
};
} // namespace __access
namespace __visitation {
struct __base {
template <class _Visitor, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto)
__visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
constexpr auto __fdiagonal = __make_fdiagonal<_Visitor&&, decltype(std::forward<_Vs>(__vs).__as_base())...>();
return __fdiagonal[__index](std::forward<_Visitor>(__visitor), std::forward<_Vs>(__vs).__as_base()...);
}
template <class _Visitor, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, _Vs&&... __vs) {
constexpr auto __fmatrix = __make_fmatrix<_Visitor&&, decltype(std::forward<_Vs>(__vs).__as_base())...>();
return __at(__fmatrix, __vs.index()...)(std::forward<_Visitor>(__visitor), std::forward<_Vs>(__vs).__as_base()...);
}
private:
template <class _Tp>
_LIBCPP_HIDE_FROM_ABI static constexpr const _Tp& __at(const _Tp& __elem) {
return __elem;
}
template <class _Tp, size_t _Np, typename... _Indices>
_LIBCPP_HIDE_FROM_ABI static constexpr auto&&
__at(const __farray<_Tp, _Np>& __elems, size_t __index, _Indices... __indices) {
return __at(__elems[__index], __indices...);
}
template <class _Fp, class... _Fs>
static _LIBCPP_HIDE_FROM_ABI constexpr void __std_visit_visitor_return_type_check() {
static_assert(
__all<is_same_v<_Fp, _Fs>...>::value, "`std::visit` requires the visitor to have a single return type.");
}
template <class... _Fs>
_LIBCPP_HIDE_FROM_ABI static constexpr auto __make_farray(_Fs&&... __fs) {
__std_visit_visitor_return_type_check<__remove_cvref_t<_Fs>...>();
using __result = __farray<common_type_t<__remove_cvref_t<_Fs>...>, sizeof...(_Fs)>;
return __result{{std::forward<_Fs>(__fs)...}};
}
template <size_t... _Is>
struct __dispatcher {
template <class _Fp, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) {
return std::__invoke(static_cast<_Fp>(__f), __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...);
}
};
template <class _Fp, class... _Vs, size_t... _Is>
_LIBCPP_HIDE_FROM_ABI static constexpr auto __make_dispatch(index_sequence<_Is...>) {
return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>;
}
template <size_t _Ip, class _Fp, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr auto __make_fdiagonal_impl() {
return __make_dispatch<_Fp, _Vs...>(index_sequence<((void)__type_identity<_Vs>{}, _Ip)...>{});
}
template <class _Fp, class... _Vs, size_t... _Is>
_LIBCPP_HIDE_FROM_ABI static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) {
return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...);
}
template <class _Fp, class _Vp, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr auto __make_fdiagonal() {
constexpr size_t __np = __remove_cvref_t<_Vp>::__size();
static_assert(__all<(__np == __remove_cvref_t<_Vs>::__size())...>::value);
return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<__np>{});
}
template <class _Fp, class... _Vs, size_t... _Is>
_LIBCPP_HIDE_FROM_ABI static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) {
return __make_dispatch<_Fp, _Vs...>(__is);
}
template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls>
_LIBCPP_HIDE_FROM_ABI static constexpr auto
__make_fmatrix_impl(index_sequence<_Is...>, index_sequence<_Js...>, _Ls... __ls) {
return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>(index_sequence<_Is..., _Js>{}, __ls...)...);
}
template <class _Fp, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr auto __make_fmatrix() {
return __make_fmatrix_impl<_Fp, _Vs...>(
index_sequence<>{}, make_index_sequence<__remove_cvref_t<_Vs>::__size()>{}...);
}
};
struct __variant {
template <class _Visitor, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto)
__visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
return __base::__visit_alt_at(__index, std::forward<_Visitor>(__visitor), std::forward<_Vs>(__vs).__impl_...);
}
template <class _Visitor, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor, _Vs&&... __vs) {
return __base::__visit_alt(
std::forward<_Visitor>(__visitor), std::__as_variant(std::forward<_Vs>(__vs)).__impl_...);
}
template <class _Visitor, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto)
__visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
return __visit_alt_at(__index, __make_value_visitor(std::forward<_Visitor>(__visitor)), std::forward<_Vs>(__vs)...);
}
template <class _Visitor, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr decltype(auto) __visit_value(_Visitor&& __visitor, _Vs&&... __vs) {
return __visit_alt(__make_value_visitor(std::forward<_Visitor>(__visitor)), std::forward<_Vs>(__vs)...);
}
# if _LIBCPP_STD_VER >= 20
template <class _Rp, class _Visitor, class... _Vs>
_LIBCPP_HIDE_FROM_ABI static constexpr _Rp __visit_value(_Visitor&& __visitor, _Vs&&... __vs) {
return __visit_alt(__make_value_visitor<_Rp>(std::forward<_Visitor>(__visitor)), std::forward<_Vs>(__vs)...);
}
# endif
private:
template <class _Visitor, class... _Values>
static _LIBCPP_HIDE_FROM_ABI constexpr void __std_visit_exhaustive_visitor_check() {
static_assert(is_invocable_v<_Visitor, _Values...>, "`std::visit` requires the visitor to be exhaustive.");
}
template <class _Visitor>
struct __value_visitor {
template <class... _Alts>
_LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator()(_Alts&&... __alts) const {
__std_visit_exhaustive_visitor_check< _Visitor, decltype((std::forward<_Alts>(__alts).__value))...>();
return std::__invoke(std::forward<_Visitor>(__visitor), std::forward<_Alts>(__alts).__value...);
}
_Visitor&& __visitor;
};
# if _LIBCPP_STD_VER >= 20
template <class _Rp, class _Visitor>
struct __value_visitor_return_type {
template <class... _Alts>
_LIBCPP_HIDE_FROM_ABI constexpr _Rp operator()(_Alts&&... __alts) const {
__std_visit_exhaustive_visitor_check< _Visitor, decltype((std::forward<_Alts>(__alts).__value))...>();
if constexpr (is_void_v<_Rp>) {
std::__invoke(std::forward<_Visitor>(__visitor), std::forward<_Alts>(__alts).__value...);
} else {
return std::__invoke(std::forward<_Visitor>(__visitor), std::forward<_Alts>(__alts).__value...);
}
}
_Visitor&& __visitor;
};
# endif
template <class _Visitor>
_LIBCPP_HIDE_FROM_ABI static constexpr auto __make_value_visitor(_Visitor&& __visitor) {
return __value_visitor<_Visitor>{std::forward<_Visitor>(__visitor)};
}
# if _LIBCPP_STD_VER >= 20
template <class _Rp, class _Visitor>
_LIBCPP_HIDE_FROM_ABI static constexpr auto __make_value_visitor(_Visitor&& __visitor) {
return __value_visitor_return_type<_Rp, _Visitor>{std::forward<_Visitor>(__visitor)};
}
# endif
};
} // namespace __visitation
// Adding semi-colons in macro expansions helps clang-format to do a better job.
// This macro is used to avoid compilation errors due to "stray" semi-colons.
# define _LIBCPP_EAT_SEMICOLON static_assert(true, "")
template <size_t _Index, class _Tp>
struct _LIBCPP_TEMPLATE_VIS __alt {
using __value_type = _Tp;
static constexpr size_t __index = _Index;
template <class... _Args>
_LIBCPP_HIDE_FROM_ABI explicit constexpr __alt(in_place_t, _Args&&... __args)
: __value(std::forward<_Args>(__args)...) {}
__value_type __value;
};
template <_Trait _DestructibleTrait, size_t _Index, class... _Types>
union _LIBCPP_TEMPLATE_VIS __union;
template <_Trait _DestructibleTrait, size_t _Index>
union _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {};
# define _LIBCPP_VARIANT_UNION(destructible_trait, destructor_definition) \
template <size_t _Index, class _Tp, class... _Types> \
union _LIBCPP_TEMPLATE_VIS __union<destructible_trait, _Index, _Tp, _Types...> { \
public: \
_LIBCPP_HIDE_FROM_ABI explicit constexpr __union(__valueless_t) noexcept : __dummy{} {} \
\
template <class... _Args> \
_LIBCPP_HIDE_FROM_ABI explicit constexpr __union(in_place_index_t<0>, _Args&&... __args) \
: __head(in_place, std::forward<_Args>(__args)...) {} \
\
template <size_t _Ip, class... _Args> \
_LIBCPP_HIDE_FROM_ABI explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args) \
: __tail(in_place_index<_Ip - 1>, std::forward<_Args>(__args)...) {} \
\
_LIBCPP_HIDE_FROM_ABI __union(const __union&) = default; \
_LIBCPP_HIDE_FROM_ABI __union(__union&&) = default; \
_LIBCPP_HIDE_FROM_ABI __union& operator=(const __union&) = default; \
_LIBCPP_HIDE_FROM_ABI __union& operator=(__union&&) = default; \
destructor_definition; \
\
private: \
char __dummy; \
__alt<_Index, _Tp> __head; \
__union<destructible_trait, _Index + 1, _Types...> __tail; \
\
friend struct __access::__union; \
}
_LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__union() = default);
_LIBCPP_VARIANT_UNION(
_Trait::_Available, _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__union() {} _LIBCPP_EAT_SEMICOLON);
_LIBCPP_VARIANT_UNION(_Trait::_Unavailable, _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__union() = delete);
# undef _LIBCPP_VARIANT_UNION
template <_Trait _DestructibleTrait, class... _Types>
class _LIBCPP_TEMPLATE_VIS __base {
public:
using __index_t = __variant_index_t<sizeof...(_Types)>;
_LIBCPP_HIDE_FROM_ABI explicit constexpr __base(__valueless_t __tag) noexcept
: __data(__tag), __index(__variant_npos<__index_t>) {}
template <size_t _Ip, class... _Args>
_LIBCPP_HIDE_FROM_ABI explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args)
: __data(in_place_index<_Ip>, std::forward<_Args>(__args)...), __index(_Ip) {}
_LIBCPP_HIDE_FROM_ABI constexpr bool valueless_by_exception() const noexcept { return index() == variant_npos; }
_LIBCPP_HIDE_FROM_ABI constexpr size_t index() const noexcept {
return __index == __variant_npos<__index_t> ? variant_npos : __index;
}
protected:
_LIBCPP_HIDE_FROM_ABI constexpr auto&& __as_base() & { return *this; }
_LIBCPP_HIDE_FROM_ABI constexpr auto&& __as_base() && { return std::move(*this); }
_LIBCPP_HIDE_FROM_ABI constexpr auto&& __as_base() const& { return *this; }
_LIBCPP_HIDE_FROM_ABI constexpr auto&& __as_base() const&& { return std::move(*this); }
_LIBCPP_HIDE_FROM_ABI static constexpr size_t __size() { return sizeof...(_Types); }
__union<_DestructibleTrait, 0, _Types...> __data;
__index_t __index;
friend struct __access::__base;
friend struct __visitation::__base;
};
template <class _Traits, _Trait = _Traits::__destructible_trait>
class _LIBCPP_TEMPLATE_VIS __dtor;
# define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor_definition, destroy) \
template <class... _Types> \
class _LIBCPP_TEMPLATE_VIS __dtor<__traits<_Types...>, destructible_trait> \
: public __base<destructible_trait, _Types...> { \
using __base_type = __base<destructible_trait, _Types...>; \
using __index_t = typename __base_type::__index_t; \
\
public: \
using __base_type::__base_type; \
using __base_type::operator=; \
_LIBCPP_HIDE_FROM_ABI __dtor(const __dtor&) = default; \
_LIBCPP_HIDE_FROM_ABI __dtor(__dtor&&) = default; \
_LIBCPP_HIDE_FROM_ABI __dtor& operator=(const __dtor&) = default; \
_LIBCPP_HIDE_FROM_ABI __dtor& operator=(__dtor&&) = default; \
destructor_definition; \
\
protected: \
destroy; \
}
_LIBCPP_VARIANT_DESTRUCTOR(
_Trait::_TriviallyAvailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__dtor() = default,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy() noexcept {
this->__index = __variant_npos<__index_t>;
} _LIBCPP_EAT_SEMICOLON);
_LIBCPP_VARIANT_DESTRUCTOR(
_Trait::_Available,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__dtor() { __destroy(); } _LIBCPP_EAT_SEMICOLON,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy() noexcept {
if (!this->valueless_by_exception()) {
__visitation::__base::__visit_alt(
[](auto& __alt) noexcept {
using __alt_type = __remove_cvref_t<decltype(__alt)>;
__alt.~__alt_type();
},
*this);
}
this->__index = __variant_npos<__index_t>;
} _LIBCPP_EAT_SEMICOLON);
_LIBCPP_VARIANT_DESTRUCTOR(_Trait::_Unavailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__dtor() = delete,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __destroy() noexcept = delete);
# undef _LIBCPP_VARIANT_DESTRUCTOR
template <class _Traits>
class _LIBCPP_TEMPLATE_VIS __ctor : public __dtor<_Traits> {
using __base_type = __dtor<_Traits>;
public:
using __base_type::__base_type;
using __base_type::operator=;
protected:
template <class _Rhs>
_LIBCPP_HIDE_FROM_ABI static _LIBCPP_CONSTEXPR_SINCE_CXX20 void __generic_construct(__ctor& __lhs, _Rhs&& __rhs) {
__lhs.__destroy();
if (!__rhs.valueless_by_exception()) {
auto __rhs_index = __rhs.index();
__visitation::__base::__visit_alt_at(
__rhs_index,
[&__lhs](auto&& __rhs_alt) {
std::__construct_at(std::addressof(__lhs.__data),
in_place_index<__decay_t<decltype(__rhs_alt)>::__index>,
std::forward<decltype(__rhs_alt)>(__rhs_alt).__value);
},
std::forward<_Rhs>(__rhs));
__lhs.__index = __rhs_index;
}
}
};
template <class _Traits, _Trait = _Traits::__move_constructible_trait>
class _LIBCPP_TEMPLATE_VIS __move_constructor;
# define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait, move_constructor_definition) \
template <class... _Types> \
class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>, move_constructible_trait> \
: public __ctor<__traits<_Types...>> { \
using __base_type = __ctor<__traits<_Types...>>; \
\
public: \
using __base_type::__base_type; \
using __base_type::operator=; \
\
_LIBCPP_HIDE_FROM_ABI __move_constructor(const __move_constructor&) = default; \
_LIBCPP_HIDE_FROM_ABI ~__move_constructor() = default; \
_LIBCPP_HIDE_FROM_ABI __move_constructor& operator=(const __move_constructor&) = default; \
_LIBCPP_HIDE_FROM_ABI __move_constructor& operator=(__move_constructor&&) = default; \
move_constructor_definition; \
}
_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
_Trait::_TriviallyAvailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_constructor(__move_constructor&& __that) = default);
_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
_Trait::_Available,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_constructor(__move_constructor&& __that) noexcept(
__all<is_nothrow_move_constructible_v<_Types>...>::value)
: __move_constructor(__valueless_t{}) {
this->__generic_construct(*this, std::move(__that));
} _LIBCPP_EAT_SEMICOLON);
_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
_Trait::_Unavailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_constructor(__move_constructor&&) = delete);
# undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR
template <class _Traits, _Trait = _Traits::__copy_constructible_trait>
class _LIBCPP_TEMPLATE_VIS __copy_constructor;
# define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait, copy_constructor_definition) \
template <class... _Types> \
class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>, copy_constructible_trait> \
: public __move_constructor<__traits<_Types...>> { \
using __base_type = __move_constructor<__traits<_Types...>>; \
\
public: \
using __base_type::__base_type; \
using __base_type::operator=; \
\
_LIBCPP_HIDE_FROM_ABI __copy_constructor(__copy_constructor&&) = default; \
_LIBCPP_HIDE_FROM_ABI ~__copy_constructor() = default; \
_LIBCPP_HIDE_FROM_ABI __copy_constructor& operator=(const __copy_constructor&) = default; \
_LIBCPP_HIDE_FROM_ABI __copy_constructor& operator=(__copy_constructor&&) = default; \
copy_constructor_definition; \
}
_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
_Trait::_TriviallyAvailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_constructor(const __copy_constructor& __that) = default);
_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
_Trait::_Available,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_constructor(const __copy_constructor& __that)
: __copy_constructor(__valueless_t{}) { this->__generic_construct(*this, __that); } _LIBCPP_EAT_SEMICOLON);
_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
_Trait::_Unavailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_constructor(const __copy_constructor&) = delete);
# undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR
template <class _Traits>
class _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> {
using __base_type = __copy_constructor<_Traits>;
public:
using __base_type::__base_type;
using __base_type::operator=;
template <size_t _Ip, class... _Args>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 auto& __emplace(_Args&&... __args) {
this->__destroy();
std::__construct_at(std::addressof(this->__data), in_place_index<_Ip>, std::forward<_Args>(__args)...);
this->__index = _Ip;
return __access::__base::__get_alt<_Ip>(*this).__value;
}
protected:
template <size_t _Ip, class _Tp, class _Arg>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) {
if (this->index() == _Ip) {
__a.__value = std::forward<_Arg>(__arg);
} else {
struct {
_LIBCPP_HIDDEN _LIBCPP_CONSTEXPR_SINCE_CXX20 void operator()(true_type) const {
__this->__emplace<_Ip>(std::forward<_Arg>(__arg));
}
_LIBCPP_HIDDEN _LIBCPP_CONSTEXPR_SINCE_CXX20 void operator()(false_type) const {
__this->__emplace<_Ip>(_Tp(std::forward<_Arg>(__arg)));
}
__assignment* __this;
_Arg&& __arg;
} __impl{this, std::forward<_Arg>(__arg)};
__impl(bool_constant < is_nothrow_constructible_v<_Tp, _Arg> || !is_nothrow_move_constructible_v < _Tp >> {});
}
}
template <class _That>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __generic_assign(_That&& __that) {
if (this->valueless_by_exception() && __that.valueless_by_exception()) {
// do nothing.
} else if (__that.valueless_by_exception()) {
this->__destroy();
} else {
__visitation::__base::__visit_alt_at(
__that.index(),
[this](auto& __this_alt, auto&& __that_alt) {
this->__assign_alt(__this_alt, std::forward<decltype(__that_alt)>(__that_alt).__value);
},
*this,
std::forward<_That>(__that));
}
}
};
template <class _Traits, _Trait = _Traits::__move_assignable_trait>
class _LIBCPP_TEMPLATE_VIS __move_assignment;
# define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait, move_assignment_definition) \
template <class... _Types> \
class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>, move_assignable_trait> \
: public __assignment<__traits<_Types...>> { \
using __base_type = __assignment<__traits<_Types...>>; \
\
public: \
using __base_type::__base_type; \
using __base_type::operator=; \
\
_LIBCPP_HIDE_FROM_ABI __move_assignment(const __move_assignment&) = default; \
_LIBCPP_HIDE_FROM_ABI __move_assignment(__move_assignment&&) = default; \
_LIBCPP_HIDE_FROM_ABI ~__move_assignment() = default; \
_LIBCPP_HIDE_FROM_ABI __move_assignment& operator=(const __move_assignment&) = default; \
move_assignment_definition; \
}
_LIBCPP_VARIANT_MOVE_ASSIGNMENT(_Trait::_TriviallyAvailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_assignment& operator=(
__move_assignment&& __that) = default);
_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
_Trait::_Available,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_assignment&
operator=(__move_assignment&& __that) noexcept(
__all<(is_nothrow_move_constructible_v<_Types> && is_nothrow_move_assignable_v<_Types>)...>::value) {
this->__generic_assign(std::move(__that));
return *this;
} _LIBCPP_EAT_SEMICOLON);
_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
_Trait::_Unavailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __move_assignment& operator=(__move_assignment&&) = delete);
# undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT
template <class _Traits, _Trait = _Traits::__copy_assignable_trait>
class _LIBCPP_TEMPLATE_VIS __copy_assignment;
# define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait, copy_assignment_definition) \
template <class... _Types> \
class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>, copy_assignable_trait> \
: public __move_assignment<__traits<_Types...>> { \
using __base_type = __move_assignment<__traits<_Types...>>; \
\
public: \
using __base_type::__base_type; \
using __base_type::operator=; \
\
_LIBCPP_HIDE_FROM_ABI __copy_assignment(const __copy_assignment&) = default; \
_LIBCPP_HIDE_FROM_ABI __copy_assignment(__copy_assignment&&) = default; \
_LIBCPP_HIDE_FROM_ABI ~__copy_assignment() = default; \
_LIBCPP_HIDE_FROM_ABI __copy_assignment& operator=(__copy_assignment&&) = default; \
copy_assignment_definition; \
}
_LIBCPP_VARIANT_COPY_ASSIGNMENT(_Trait::_TriviallyAvailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_assignment& operator=(
const __copy_assignment& __that) = default);
_LIBCPP_VARIANT_COPY_ASSIGNMENT(
_Trait::_Available,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_assignment&
operator=(const __copy_assignment& __that) {
this->__generic_assign(__that);
return *this;
} _LIBCPP_EAT_SEMICOLON);
_LIBCPP_VARIANT_COPY_ASSIGNMENT(_Trait::_Unavailable,
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __copy_assignment& operator=(
const __copy_assignment&) = delete);
# undef _LIBCPP_VARIANT_COPY_ASSIGNMENT
template <class... _Types>
class _LIBCPP_TEMPLATE_VIS __impl : public __copy_assignment<__traits<_Types...>> {
using __base_type = __copy_assignment<__traits<_Types...>>;
public:
using __base_type::__base_type; // get in_place_index_t constructor & friends
_LIBCPP_HIDE_FROM_ABI __impl(__impl const&) = default;
_LIBCPP_HIDE_FROM_ABI __impl(__impl&&) = default;
_LIBCPP_HIDE_FROM_ABI __impl& operator=(__impl const&) = default;
_LIBCPP_HIDE_FROM_ABI __impl& operator=(__impl&&) = default;
template <size_t _Ip, class _Arg>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __assign(_Arg&& __arg) {
this->__assign_alt(__access::__base::__get_alt<_Ip>(*this), std::forward<_Arg>(__arg));
}
inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void __swap(__impl& __that) {
if (this->valueless_by_exception() && __that.valueless_by_exception()) {
// do nothing.
} else if (this->index() == __that.index()) {
__visitation::__base::__visit_alt_at(
this->index(),
[](auto& __this_alt, auto& __that_alt) {
using std::swap;
swap(__this_alt.__value, __that_alt.__value);
},
*this,
__that);
} else {
__impl* __lhs = this;
__impl* __rhs = std::addressof(__that);
if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) {
std::swap(__lhs, __rhs);
}
__impl __tmp(std::move(*__rhs));
# ifndef _LIBCPP_HAS_NO_EXCEPTIONS
if constexpr (__all<is_nothrow_move_constructible_v<_Types>...>::value) {
this->__generic_construct(*__rhs, std::move(*__lhs));
} else {
// EXTENSION: When the move construction of `__lhs` into `__rhs` throws
// and `__tmp` is nothrow move constructible then we move `__tmp` back
// into `__rhs` and provide the strong exception safety guarantee.
try {
this->__generic_construct(*__rhs, std::move(*__lhs));
} catch (...) {
if (__tmp.__move_nothrow()) {
this->__generic_construct(*__rhs, std::move(__tmp));
}
throw;
}
}
# else
// this isn't consolidated with the `if constexpr` branch above due to
// `throw` being ill-formed with exceptions disabled even when discarded.
this->__generic_construct(*__rhs, std::move(*__lhs));
# endif
this->__generic_construct(*__lhs, std::move(__tmp));
}
}
private:
constexpr inline _LIBCPP_HIDE_FROM_ABI bool __move_nothrow() const {
constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...};
return this->valueless_by_exception() || __results[this->index()];
}
};
struct __no_narrowing_check {
template <class _Dest, class _Source>
using _Apply = __type_identity<_Dest>;
};
struct __narrowing_check {
template <class _Dest>
static auto __test_impl(_Dest (&&)[1]) -> __type_identity<_Dest>;
template <class _Dest, class _Source>
using _Apply _LIBCPP_NODEBUG = decltype(__test_impl<_Dest>({std::declval<_Source>()}));
};
template <class _Dest, class _Source>
using __check_for_narrowing _LIBCPP_NODEBUG =
typename _If< is_arithmetic<_Dest>::value, __narrowing_check, __no_narrowing_check >::template _Apply<_Dest,
_Source>;
template <class _Tp, size_t _Idx>
struct __overload {
template <class _Up>
auto operator()(_Tp, _Up&&) const -> __check_for_narrowing<_Tp, _Up>;
};
template <class... _Bases>
struct __all_overloads : _Bases... {
void operator()() const;
using _Bases::operator()...;
};
template <class _IdxSeq>
struct __make_overloads_imp;
template <size_t... _Idx>
struct __make_overloads_imp<__tuple_indices<_Idx...> > {
template <class... _Types>
using _Apply _LIBCPP_NODEBUG = __all_overloads<__overload<_Types, _Idx>...>;
};
template <class... _Types>
using _MakeOverloads _LIBCPP_NODEBUG =
typename __make_overloads_imp< __make_indices_imp<sizeof...(_Types), 0> >::template _Apply<_Types...>;
template <class _Tp, class... _Types>
using __best_match_t = typename invoke_result_t<_MakeOverloads<_Types...>, _Tp, _Tp>::type;
} // namespace __variant_detail
template <class _Visitor, class... _Vs, typename = void_t<decltype(std::__as_variant(std::declval<_Vs>()))...>>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr decltype(auto)
visit(_Visitor&& __visitor, _Vs&&... __vs);
# if _LIBCPP_STD_VER >= 20
template <class _Rp,
class _Visitor,
class... _Vs,
typename = void_t<decltype(std::__as_variant(std::declval<_Vs>()))...>>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr _Rp
visit(_Visitor&& __visitor, _Vs&&... __vs);
# endif
template <class... _Types>
class _LIBCPP_TEMPLATE_VIS _LIBCPP_DECLSPEC_EMPTY_BASES variant
: private __sfinae_ctor_base< __all<is_copy_constructible_v<_Types>...>::value,
__all<is_move_constructible_v<_Types>...>::value>,
private __sfinae_assign_base<
__all<(is_copy_constructible_v<_Types> && is_copy_assignable_v<_Types>)...>::value,
__all<(is_move_constructible_v<_Types> && is_move_assignable_v<_Types>)...>::value> {
static_assert(0 < sizeof...(_Types), "variant must consist of at least one alternative.");
static_assert(__all<!is_array_v<_Types>...>::value, "variant can not have an array type as an alternative.");
static_assert(__all<!is_reference_v<_Types>...>::value, "variant can not have a reference type as an alternative.");
static_assert(__all<!is_void_v<_Types>...>::value, "variant can not have a void type as an alternative.");
using __first_type = variant_alternative_t<0, variant>;
public:
using __trivially_relocatable =
conditional_t<_And<__libcpp_is_trivially_relocatable<_Types>...>::value, variant, void>;
template <bool _Dummy = true,
enable_if_t<__dependent_type<is_default_constructible<__first_type>, _Dummy>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>)
: __impl_(in_place_index<0>) {}
_LIBCPP_HIDE_FROM_ABI constexpr variant(const variant&) = default;
_LIBCPP_HIDE_FROM_ABI constexpr variant(variant&&) = default;
template < class _Arg,
enable_if_t<!is_same_v<__remove_cvref_t<_Arg>, variant>, int> = 0,
enable_if_t<!__is_inplace_type<__remove_cvref_t<_Arg>>::value, int> = 0,
enable_if_t<!__is_inplace_index<__remove_cvref_t<_Arg>>::value, int> = 0,
class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0>
_LIBCPP_HIDE_FROM_ABI constexpr variant(_Arg&& __arg) noexcept(is_nothrow_constructible_v<_Tp, _Arg>)
: __impl_(in_place_index<_Ip>, std::forward<_Arg>(__arg)) {}
template <size_t _Ip,
class... _Args,
class = enable_if_t<(_Ip < sizeof...(_Types)), int>,
class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
_LIBCPP_HIDE_FROM_ABI explicit constexpr variant(in_place_index_t<_Ip>, _Args&&... __args) noexcept(
is_nothrow_constructible_v<_Tp, _Args...>)
: __impl_(in_place_index<_Ip>, std::forward<_Args>(__args)...) {}
template < size_t _Ip,
class _Up,
class... _Args,
enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, int> = 0>
_LIBCPP_HIDE_FROM_ABI explicit constexpr variant(
in_place_index_t<_Ip>,
initializer_list<_Up> __il,
_Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>)
: __impl_(in_place_index<_Ip>, __il, std::forward<_Args>(__args)...) {}
template < class _Tp,
class... _Args,
size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
_LIBCPP_HIDE_FROM_ABI explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept(
is_nothrow_constructible_v<_Tp, _Args...>)
: __impl_(in_place_index<_Ip>, std::forward<_Args>(__args)...) {}
template < class _Tp,
class _Up,
class... _Args,
size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, int> = 0>
_LIBCPP_HIDE_FROM_ABI explicit constexpr variant(
in_place_type_t<_Tp>,
initializer_list<_Up> __il,
_Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>)
: __impl_(in_place_index<_Ip>, __il, std::forward<_Args>(__args)...) {}
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~variant() = default;
_LIBCPP_HIDE_FROM_ABI constexpr variant& operator=(const variant&) = default;
_LIBCPP_HIDE_FROM_ABI constexpr variant& operator=(variant&&) = default;
template < class _Arg,
enable_if_t<!is_same_v<__remove_cvref_t<_Arg>, variant>, int> = 0,
class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 variant&
operator=(_Arg&& __arg) noexcept(is_nothrow_assignable_v<_Tp&, _Arg> && is_nothrow_constructible_v<_Tp, _Arg>) {
__impl_.template __assign<_Ip>(std::forward<_Arg>(__arg));
return *this;
}
template < size_t _Ip,
class... _Args,
enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& emplace(_Args&&... __args) {
return __impl_.template __emplace<_Ip>(std::forward<_Args>(__args)...);
}
template < size_t _Ip,
class _Up,
class... _Args,
enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
return __impl_.template __emplace<_Ip>(__il, std::forward<_Args>(__args)...);
}
template < class _Tp,
class... _Args,
size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& emplace(_Args&&... __args) {
return __impl_.template __emplace<_Ip>(std::forward<_Args>(__args)...);
}
template < class _Tp,
class _Up,
class... _Args,
size_t _Ip = __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>, int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
return __impl_.template __emplace<_Ip>(__il, std::forward<_Args>(__args)...);
}
_LIBCPP_HIDE_FROM_ABI constexpr bool valueless_by_exception() const noexcept {
return __impl_.valueless_by_exception();
}
_LIBCPP_HIDE_FROM_ABI constexpr size_t index() const noexcept { return __impl_.index(); }
template < bool _Dummy = true,
enable_if_t< __all<(__dependent_type<is_move_constructible<_Types>, _Dummy>::value &&
__dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value,
int> = 0>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(variant& __that) noexcept(
__all<(is_nothrow_move_constructible_v<_Types> && is_nothrow_swappable_v<_Types>)...>::value) {
__impl_.__swap(__that.__impl_);
}
# if _LIBCPP_STD_VER >= 26 && defined(_LIBCPP_HAS_EXPLICIT_THIS_PARAMETER)
// Helper class to implement [variant.visit]/10
// Constraints: The call to visit does not use an explicit template-argument-list
// that begins with a type template-argument.
struct __variant_visit_barrier_tag {
_LIBCPP_HIDE_FROM_ABI explicit __variant_visit_barrier_tag() = default;
};
template <__variant_visit_barrier_tag = __variant_visit_barrier_tag{}, class _Self, class _Visitor>
_LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) visit(this _Self&& __self, _Visitor&& __visitor) {
using _VariantT = _OverrideRef<_Self&&, _CopyConst<remove_reference_t<_Self>, variant>>;
return std::visit(std::forward<_Visitor>(__visitor), (_VariantT)__self);
}
template <class _Rp, class _Self, class _Visitor>
_LIBCPP_HIDE_FROM_ABI constexpr _Rp visit(this _Self&& __self, _Visitor&& __visitor) {
using _VariantT = _OverrideRef<_Self&&, _CopyConst<remove_reference_t<_Self>, variant>>;
return std::visit<_Rp>(std::forward<_Visitor>(__visitor), (_VariantT)__self);
}
# endif
private:
__variant_detail::__impl<_Types...> __impl_;
friend struct __variant_detail::__access::__variant;
friend struct __variant_detail::__visitation::__variant;
};
template <size_t _Ip, class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept {
return __v.index() == _Ip;
}
template <class _Tp, class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr bool holds_alternative(const variant<_Types...>& __v) noexcept {
return std::__holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
}
template <size_t _Ip, class _Vp>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr auto&& __generic_get(_Vp&& __v) {
using __variant_detail::__access::__variant;
if (!std::__holds_alternative<_Ip>(__v)) {
__throw_bad_variant_access();
}
return __variant::__get_alt<_Ip>(std::forward<_Vp>(__v)).__value;
}
template <size_t _Ip, class... _Types>
_LIBCPP_HIDE_FROM_ABI
_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr variant_alternative_t<_Ip, variant<_Types...>>&
get(variant<_Types...>& __v) {
static_assert(_Ip < sizeof...(_Types));
static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
return std::__generic_get<_Ip>(__v);
}
template <size_t _Ip, class... _Types>
_LIBCPP_HIDE_FROM_ABI
_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr variant_alternative_t<_Ip, variant<_Types...>>&&
get(variant<_Types...>&& __v) {
static_assert(_Ip < sizeof...(_Types));
static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
return std::__generic_get<_Ip>(std::move(__v));
}
template <size_t _Ip, class... _Types>
_LIBCPP_HIDE_FROM_ABI
_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr const variant_alternative_t<_Ip, variant<_Types...>>&
get(const variant<_Types...>& __v) {
static_assert(_Ip < sizeof...(_Types));
static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
return std::__generic_get<_Ip>(__v);
}
template <size_t _Ip, class... _Types>
_LIBCPP_HIDE_FROM_ABI
_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr const variant_alternative_t<_Ip, variant<_Types...>>&&
get(const variant<_Types...>&& __v) {
static_assert(_Ip < sizeof...(_Types));
static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
return std::__generic_get<_Ip>(std::move(__v));
}
template <class _Tp, class... _Types>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr _Tp& get(variant<_Types...>& __v) {
static_assert(!is_void_v<_Tp>);
return std::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
}
template <class _Tp, class... _Types>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr _Tp&& get(variant<_Types...>&& __v) {
static_assert(!is_void_v<_Tp>);
return std::get<__find_exactly_one_t<_Tp, _Types...>::value>(std::move(__v));
}
template <class _Tp, class... _Types>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr const _Tp&
get(const variant<_Types...>& __v) {
static_assert(!is_void_v<_Tp>);
return std::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
}
template <class _Tp, class... _Types>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr const _Tp&&
get(const variant<_Types...>&& __v) {
static_assert(!is_void_v<_Tp>);
return std::get<__find_exactly_one_t<_Tp, _Types...>::value>(std::move(__v));
}
template <size_t _Ip, class _Vp>
_LIBCPP_HIDE_FROM_ABI constexpr auto* __generic_get_if(_Vp* __v) noexcept {
using __variant_detail::__access::__variant;
return __v && std::__holds_alternative<_Ip>(*__v) ? std::addressof(__variant::__get_alt<_Ip>(*__v).__value) : nullptr;
}
template <size_t _Ip, class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>>
get_if(variant<_Types...>* __v) noexcept {
static_assert(_Ip < sizeof...(_Types));
static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
return std::__generic_get_if<_Ip>(__v);
}
template <size_t _Ip, class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>>
get_if(const variant<_Types...>* __v) noexcept {
static_assert(_Ip < sizeof...(_Types));
static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
return std::__generic_get_if<_Ip>(__v);
}
template <class _Tp, class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<_Tp> get_if(variant<_Types...>* __v) noexcept {
static_assert(!is_void_v<_Tp>);
return std::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
}
template <class _Tp, class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr add_pointer_t<const _Tp> get_if(const variant<_Types...>* __v) noexcept {
static_assert(!is_void_v<_Tp>);
return std::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
}
template <class _Operator>
struct __convert_to_bool {
template <class _T1, class _T2>
_LIBCPP_HIDE_FROM_ABI constexpr bool operator()(_T1&& __t1, _T2&& __t2) const {
static_assert(is_convertible<decltype(_Operator{}(std::forward<_T1>(__t1), std::forward<_T2>(__t2))), bool>::value,
"the relational operator does not return a type which is implicitly convertible to bool");
return _Operator{}(std::forward<_T1>(__t1), std::forward<_T2>(__t2));
}
};
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr bool operator==(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) {
using __variant_detail::__visitation::__variant;
if (__lhs.index() != __rhs.index())
return false;
if (__lhs.valueless_by_exception())
return true;
return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<equal_to<>>{}, __lhs, __rhs);
}
# if _LIBCPP_STD_VER >= 20
template <class... _Types>
requires(three_way_comparable<_Types> && ...)
_LIBCPP_HIDE_FROM_ABI constexpr common_comparison_category_t<compare_three_way_result_t<_Types>...>
operator<=>(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) {
using __variant_detail::__visitation::__variant;
using __result_t = common_comparison_category_t<compare_three_way_result_t<_Types>...>;
if (__lhs.valueless_by_exception() && __rhs.valueless_by_exception())
return strong_ordering::equal;
if (__lhs.valueless_by_exception())
return strong_ordering::less;
if (__rhs.valueless_by_exception())
return strong_ordering::greater;
if (auto __c = __lhs.index() <=> __rhs.index(); __c != 0)
return __c;
auto __three_way = []<class _Type>(const _Type& __v, const _Type& __w) -> __result_t { return __v <=> __w; };
return __variant::__visit_value_at(__lhs.index(), __three_way, __lhs, __rhs);
}
# endif // _LIBCPP_STD_VER >= 20
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr bool operator!=(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) {
using __variant_detail::__visitation::__variant;
if (__lhs.index() != __rhs.index())
return true;
if (__lhs.valueless_by_exception())
return false;
return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<not_equal_to<>>{}, __lhs, __rhs);
}
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr bool operator<(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) {
using __variant_detail::__visitation::__variant;
if (__rhs.valueless_by_exception())
return false;
if (__lhs.valueless_by_exception())
return true;
if (__lhs.index() < __rhs.index())
return true;
if (__lhs.index() > __rhs.index())
return false;
return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<less<>>{}, __lhs, __rhs);
}
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr bool operator>(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) {
using __variant_detail::__visitation::__variant;
if (__lhs.valueless_by_exception())
return false;
if (__rhs.valueless_by_exception())
return true;
if (__lhs.index() > __rhs.index())
return true;
if (__lhs.index() < __rhs.index())
return false;
return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<greater<>>{}, __lhs, __rhs);
}
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr bool operator<=(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) {
using __variant_detail::__visitation::__variant;
if (__lhs.valueless_by_exception())
return true;
if (__rhs.valueless_by_exception())
return false;
if (__lhs.index() < __rhs.index())
return true;
if (__lhs.index() > __rhs.index())
return false;
return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<less_equal<>>{}, __lhs, __rhs);
}
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr bool operator>=(const variant<_Types...>& __lhs, const variant<_Types...>& __rhs) {
using __variant_detail::__visitation::__variant;
if (__rhs.valueless_by_exception())
return true;
if (__lhs.valueless_by_exception())
return false;
if (__lhs.index() > __rhs.index())
return true;
if (__lhs.index() < __rhs.index())
return false;
return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<greater_equal<>>{}, __lhs, __rhs);
}
template <class... _Vs>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr void __throw_if_valueless(_Vs&&... __vs) {
const bool __valueless = (... || std::__as_variant(__vs).valueless_by_exception());
if (__valueless) {
__throw_bad_variant_access();
}
}
template < class _Visitor, class... _Vs, typename>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr decltype(auto)
visit(_Visitor&& __visitor, _Vs&&... __vs) {
using __variant_detail::__visitation::__variant;
std::__throw_if_valueless(std::forward<_Vs>(__vs)...);
return __variant::__visit_value(std::forward<_Visitor>(__visitor), std::forward<_Vs>(__vs)...);
}
# if _LIBCPP_STD_VER >= 20
template < class _Rp, class _Visitor, class... _Vs, typename>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr _Rp
visit(_Visitor&& __visitor, _Vs&&... __vs) {
using __variant_detail::__visitation::__variant;
std::__throw_if_valueless(std::forward<_Vs>(__vs)...);
return __variant::__visit_value<_Rp>(std::forward<_Visitor>(__visitor), std::forward<_Vs>(__vs)...);
}
# endif
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 auto
swap(variant<_Types...>& __lhs,
variant<_Types...>& __rhs) noexcept(noexcept(__lhs.swap(__rhs))) -> decltype(__lhs.swap(__rhs)) {
return __lhs.swap(__rhs);
}
template <class... _Types>
struct _LIBCPP_TEMPLATE_VIS hash< __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> {
using argument_type = variant<_Types...>;
using result_type = size_t;
_LIBCPP_HIDE_FROM_ABI result_type operator()(const argument_type& __v) const {
using __variant_detail::__visitation::__variant;
size_t __res =
__v.valueless_by_exception()
? 299792458 // Random value chosen by the universe upon creation
: __variant::__visit_alt(
[](const auto& __alt) {
using __alt_type = __remove_cvref_t<decltype(__alt)>;
using __value_type = remove_const_t< typename __alt_type::__value_type>;
return hash<__value_type>{}(__alt.__value);
},
__v);
return std::__hash_combine(__res, hash<size_t>{}(__v.index()));
}
};
// __unchecked_get is the same as std::get, except, it is UB to use it with the wrong
// type whereas std::get will throw or returning nullptr. This makes it faster than
// std::get.
template <size_t _Ip, class _Vp>
_LIBCPP_HIDE_FROM_ABI constexpr auto&& __unchecked_get(_Vp&& __v) noexcept {
using __variant_detail::__access::__variant;
return __variant::__get_alt<_Ip>(std::forward<_Vp>(__v)).__value;
}
template <class _Tp, class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr auto&& __unchecked_get(const variant<_Types...>& __v) noexcept {
return std::__unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
}
template <class _Tp, class... _Types>
_LIBCPP_HIDE_FROM_ABI constexpr auto&& __unchecked_get(variant<_Types...>& __v) noexcept {
return std::__unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
}
#endif // _LIBCPP_STD_VER >= 17
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
# include <exception>
# include <tuple>
# include <type_traits>
# include <typeinfo>
# include <utility>
#endif
#endif // _LIBCPP_VARIANT
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