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zig/lib/libcxx/include/variant
Andrew Kelley 1eaf180dd0 update libcxx to llvm 16
2023-01-26 16:36:13 -07:00

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// -*- 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
~variant();
// 20.7.2.3, assignment
constexpr variant& operator=(const variant&);
constexpr variant& operator=(variant&&) noexcept(see below);
template <class T> variant& operator=(T&&) noexcept(see below);
// 20.7.2.4, modifiers
template <class T, class... Args>
T& emplace(Args&&...);
template <class T, class U, class... Args>
T& emplace(initializer_list<U>, Args&&...);
template <size_t I, class... Args>
variant_alternative_t<I, variant>& emplace(Args&&...);
template <size_t I, class U, class... Args>
variant_alternative_t<I, variant>& emplace(initializer_list<U>, Args&&...);
// 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);
};
// 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 <__assert> // all public C++ headers provide the assertion handler
#include <__availability>
#include <__compare/common_comparison_category.h>
#include <__compare/compare_three_way_result.h>
#include <__compare/three_way_comparable.h>
#include <__config>
#include <__functional/hash.h>
#include <__functional/invoke.h>
#include <__functional/operations.h>
#include <__functional/unary_function.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/dependent_type.h>
#include <__type_traits/is_array.h>
#include <__type_traits/is_destructible.h>
#include <__type_traits/is_nothrow_move_constructible.h>
#include <__type_traits/is_trivially_copy_assignable.h>
#include <__type_traits/is_trivially_copy_constructible.h>
#include <__type_traits/is_trivially_destructible.h>
#include <__type_traits/is_trivially_move_assignable.h>
#include <__type_traits/is_trivially_move_constructible.h>
#include <__type_traits/is_void.h>
#include <__type_traits/remove_const.h>
#include <__type_traits/type_identity.h>
#include <__type_traits/void_t.h>
#include <__utility/forward.h>
#include <__utility/in_place.h>
#include <__utility/move.h>
#include <__utility/swap.h>
#include <__variant/monostate.h>
#include <exception>
#include <initializer_list>
#include <limits>
#include <new>
#include <tuple>
#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_EXCEPTION_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 > 14
// 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_INLINE_VISIBILITY constexpr
const _Tp &operator[](size_t __n) const noexcept {
return __buf_[__n];
}
};
_LIBCPP_NORETURN
inline _LIBCPP_HIDE_FROM_ABI
_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
void __throw_bad_variant_access() {
#ifndef _LIBCPP_NO_EXCEPTIONS
throw bad_variant_access();
#else
_VSTD::abort();
#endif
}
template <class... _Types>
class _LIBCPP_TEMPLATE_VIS variant;
template <class _Tp>
struct _LIBCPP_TEMPLATE_VIS variant_size;
template <class _Tp>
inline constexpr size_t variant_size_v = variant_size<_Tp>::value;
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)> {};
template <size_t _Ip, class _Tp>
struct _LIBCPP_TEMPLATE_VIS variant_alternative;
template <size_t _Ip, class _Tp>
using variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type;
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...>;
};
inline constexpr size_t variant_npos = static_cast<size_t>(-1);
_LIBCPP_HIDE_FROM_ABI constexpr int __choose_index_type(unsigned int __num_elem) {
if (__num_elem < numeric_limits<unsigned char>::max())
return 0;
if (__num_elem < numeric_limits<unsigned short>::max())
return 1;
return 2;
}
template <size_t _NumAlts>
using __variant_index_t =
#ifndef _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION
unsigned int;
#else
std::tuple_element_t<
__choose_index_type(_NumAlts),
std::tuple<unsigned char, unsigned short, unsigned int>
>;
#endif
template <class _IndexType>
constexpr _IndexType __variant_npos = static_cast<_IndexType>(-1);
template <class... _Types>
class _LIBCPP_TEMPLATE_VIS variant;
template <class... _Types>
_LIBCPP_INLINE_VISIBILITY constexpr variant<_Types...>&
__as_variant(variant<_Types...>& __vs) noexcept {
return __vs;
}
template <class... _Types>
_LIBCPP_INLINE_VISIBILITY constexpr const variant<_Types...>&
__as_variant(const variant<_Types...>& __vs) noexcept {
return __vs;
}
template <class... _Types>
_LIBCPP_INLINE_VISIBILITY constexpr variant<_Types...>&&
__as_variant(variant<_Types...>&& __vs) noexcept {
return _VSTD::move(__vs);
}
template <class... _Types>
_LIBCPP_INLINE_VISIBILITY constexpr const variant<_Types...>&&
__as_variant(const variant<_Types...>&& __vs) noexcept {
return _VSTD::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 _VSTD::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(_VSTD::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(_VSTD::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>(_VSTD::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(_VSTD::forward<_Vs>(__vs).__as_base())...>();
return __fdiagonal[__index](_VSTD::forward<_Visitor>(__visitor),
_VSTD::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(_VSTD::forward<_Vs>(__vs).__as_base())...>();
return __at(__fmatrix, __vs.index()...)(
_VSTD::forward<_Visitor>(__visitor),
_VSTD::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 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{{_VSTD::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 _VSTD::__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,
_VSTD::forward<_Visitor>(__visitor),
_VSTD::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(
_VSTD::forward<_Visitor>(__visitor),
_VSTD::__as_variant(_VSTD::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(_VSTD::forward<_Visitor>(__visitor)),
_VSTD::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(_VSTD::forward<_Visitor>(__visitor)),
_VSTD::forward<_Vs>(__vs)...);
}
#if _LIBCPP_STD_VER > 17
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>(_VSTD::forward<_Visitor>(__visitor)),
_VSTD::forward<_Vs>(__vs)...);
}
#endif
private:
template <class _Visitor, class... _Values>
static 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((_VSTD::forward<_Alts>(__alts).__value))...>();
return _VSTD::__invoke(_VSTD::forward<_Visitor>(__visitor),
_VSTD::forward<_Alts>(__alts).__value...);
}
_Visitor&& __visitor;
};
#if _LIBCPP_STD_VER > 17
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((_VSTD::forward<_Alts>(__alts).__value))...>();
if constexpr (is_void_v<_Rp>) {
_VSTD::__invoke(_VSTD::forward<_Visitor>(__visitor),
_VSTD::forward<_Alts>(__alts).__value...);
}
else {
return _VSTD::__invoke(_VSTD::forward<_Visitor>(__visitor),
_VSTD::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>{_VSTD::forward<_Visitor>(__visitor)};
}
#if _LIBCPP_STD_VER > 17
template <class _Rp, class _Visitor>
_LIBCPP_HIDE_FROM_ABI
static constexpr auto __make_value_visitor(_Visitor&& __visitor) {
return __value_visitor_return_type<_Rp, _Visitor>{_VSTD::forward<_Visitor>(__visitor)};
}
#endif
};
} // namespace __visitation
template <size_t _Index, class _Tp>
struct _LIBCPP_TEMPLATE_VIS __alt {
using __value_type = _Tp;
template <class... _Args>
_LIBCPP_HIDE_FROM_ABI
explicit constexpr __alt(in_place_t, _Args&&... __args)
: __value(_VSTD::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) \
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, _VSTD::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>, _VSTD::forward<_Args>(__args)...) {} \
\
__union(const __union&) = default; \
__union(__union&&) = default; \
\
destructor \
\
__union& operator=(const __union&) = default; \
__union& operator=(__union&&) = default; \
\
private: \
char __dummy; \
__alt<_Index, _Tp> __head; \
__union<destructible_trait, _Index + 1, _Types...> __tail; \
\
friend struct __access::__union; \
}
_LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;);
_LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {});
_LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__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>, _VSTD::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 _VSTD::move(*this); }
_LIBCPP_HIDE_FROM_ABI
constexpr auto&& __as_base() const & { return *this; }
_LIBCPP_HIDE_FROM_ABI
constexpr auto&& __as_base() const && { return _VSTD::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, 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=; \
\
__dtor(const __dtor&) = default; \
__dtor(__dtor&&) = default; \
destructor \
__dtor& operator=(const __dtor&) = default; \
__dtor& operator=(__dtor&&) = default; \
\
protected: \
inline _LIBCPP_HIDE_FROM_ABI \
destroy \
}
_LIBCPP_VARIANT_DESTRUCTOR(
_Trait::_TriviallyAvailable,
~__dtor() = default;,
void __destroy() noexcept { this->__index = __variant_npos<__index_t>; });
_LIBCPP_VARIANT_DESTRUCTOR(
_Trait::_Available,
~__dtor() { __destroy(); },
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_VARIANT_DESTRUCTOR(
_Trait::_Unavailable,
~__dtor() = delete;,
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 <size_t _Ip, class _Tp, class... _Args>
_LIBCPP_HIDE_FROM_ABI
static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) {
::new ((void*)_VSTD::addressof(__a))
__alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...);
return __a.__value;
}
template <class _Rhs>
_LIBCPP_HIDE_FROM_ABI
static void __generic_construct(__ctor& __lhs, _Rhs&& __rhs) {
__lhs.__destroy();
if (!__rhs.valueless_by_exception()) {
__visitation::__base::__visit_alt_at(
__rhs.index(),
[](auto& __lhs_alt, auto&& __rhs_alt) {
__construct_alt(
__lhs_alt,
_VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value);
},
__lhs, _VSTD::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) \
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=; \
\
__move_constructor(const __move_constructor&) = default; \
move_constructor \
~__move_constructor() = default; \
__move_constructor& operator=(const __move_constructor&) = default; \
__move_constructor& operator=(__move_constructor&&) = default; \
}
_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
_Trait::_TriviallyAvailable,
__move_constructor(__move_constructor&& __that) = default;);
_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
_Trait::_Available,
__move_constructor(__move_constructor&& __that) noexcept(
__all<is_nothrow_move_constructible_v<_Types>...>::value)
: __move_constructor(__valueless_t{}) {
this->__generic_construct(*this, _VSTD::move(__that));
});
_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
_Trait::_Unavailable,
__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) \
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=; \
\
copy_constructor \
__copy_constructor(__copy_constructor&&) = default; \
~__copy_constructor() = default; \
__copy_constructor& operator=(const __copy_constructor&) = default; \
__copy_constructor& operator=(__copy_constructor&&) = default; \
}
_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
_Trait::_TriviallyAvailable,
__copy_constructor(const __copy_constructor& __that) = default;);
_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
_Trait::_Available,
__copy_constructor(const __copy_constructor& __that)
: __copy_constructor(__valueless_t{}) {
this->__generic_construct(*this, __that);
});
_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
_Trait::_Unavailable,
__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
auto& __emplace(_Args&&... __args) {
this->__destroy();
auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this),
_VSTD::forward<_Args>(__args)...);
this->__index = _Ip;
return __res;
}
protected:
template <size_t _Ip, class _Tp, class _Arg>
_LIBCPP_HIDE_FROM_ABI
void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) {
if (this->index() == _Ip) {
__a.__value = _VSTD::forward<_Arg>(__arg);
} else {
struct {
void operator()(true_type) const {
__this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg));
}
void operator()(false_type) const {
__this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg)));
}
__assignment* __this;
_Arg&& __arg;
} __impl{this, _VSTD::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
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,
_VSTD::forward<decltype(__that_alt)>(__that_alt).__value);
},
*this, _VSTD::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) \
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=; \
\
__move_assignment(const __move_assignment&) = default; \
__move_assignment(__move_assignment&&) = default; \
~__move_assignment() = default; \
__move_assignment& operator=(const __move_assignment&) = default; \
move_assignment \
}
_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
_Trait::_TriviallyAvailable,
__move_assignment& operator=(__move_assignment&& __that) = default;);
_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
_Trait::_Available,
__move_assignment& operator=(__move_assignment&& __that) noexcept(
__all<(is_nothrow_move_constructible_v<_Types> &&
is_nothrow_move_assignable_v<_Types>)...>::value) {
this->__generic_assign(_VSTD::move(__that));
return *this;
});
_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
_Trait::_Unavailable,
__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) \
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=; \
\
__copy_assignment(const __copy_assignment&) = default; \
__copy_assignment(__copy_assignment&&) = default; \
~__copy_assignment() = default; \
copy_assignment \
__copy_assignment& operator=(__copy_assignment&&) = default; \
}
_LIBCPP_VARIANT_COPY_ASSIGNMENT(
_Trait::_TriviallyAvailable,
__copy_assignment& operator=(const __copy_assignment& __that) = default;);
_LIBCPP_VARIANT_COPY_ASSIGNMENT(
_Trait::_Available,
__copy_assignment& operator=(const __copy_assignment& __that) {
this->__generic_assign(__that);
return *this;
});
_LIBCPP_VARIANT_COPY_ASSIGNMENT(
_Trait::_Unavailable,
__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
__impl(__impl const&) = default;
__impl(__impl&&) = default;
__impl& operator=(__impl const&) = default;
__impl& operator=(__impl&&) = default;
template <size_t _Ip, class _Arg>
_LIBCPP_HIDE_FROM_ABI
void __assign(_Arg&& __arg) {
this->__assign_alt(__access::__base::__get_alt<_Ip>(*this),
_VSTD::forward<_Arg>(__arg));
}
inline _LIBCPP_HIDE_FROM_ABI
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 _VSTD::swap;
swap(__this_alt.__value, __that_alt.__value);
},
*this,
__that);
} else {
__impl* __lhs = this;
__impl* __rhs = _VSTD::addressof(__that);
if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) {
_VSTD::swap(__lhs, __rhs);
}
__impl __tmp(_VSTD::move(*__rhs));
#ifndef _LIBCPP_NO_EXCEPTIONS
if constexpr (__all<is_nothrow_move_constructible_v<_Types>...>::value) {
this->__generic_construct(*__rhs, _VSTD::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, _VSTD::move(*__lhs));
} catch (...) {
if (__tmp.__move_nothrow()) {
this->__generic_construct(*__rhs, _VSTD::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, _VSTD::move(*__lhs));
#endif
this->__generic_construct(*__lhs, _VSTD::move(__tmp));
}
}
private:
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<
#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
false &&
#endif
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 _Tp, size_t>
struct __overload_bool {
template <class _Up, class _Ap = __remove_cvref_t<_Up>>
auto operator()(bool, _Up&&) const
-> enable_if_t<is_same_v<_Ap, bool>, __type_identity<_Tp>>;
};
template <size_t _Idx>
struct __overload<bool, _Idx> : __overload_bool<bool, _Idx> {};
template <size_t _Idx>
struct __overload<bool const, _Idx> : __overload_bool<bool const, _Idx> {};
template <size_t _Idx>
struct __overload<bool volatile, _Idx> : __overload_bool<bool volatile, _Idx> {};
template <size_t _Idx>
struct __overload<bool const volatile, _Idx> : __overload_bool<bool const volatile, _Idx> {};
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... _Types>
class _LIBCPP_TEMPLATE_VIS 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:
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>) {}
constexpr variant(const variant&) = default;
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>, _VSTD::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>, _VSTD::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, _VSTD::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>, _VSTD::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, _VSTD::forward<_Args>(__args)...) {}
~variant() = default;
constexpr variant& operator=(const variant&) = default;
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
variant& operator=(_Arg&& __arg) noexcept(
is_nothrow_assignable_v<_Tp&, _Arg> &&
is_nothrow_constructible_v<_Tp, _Arg>) {
__impl_.template __assign<_Ip>(_VSTD::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
_Tp& emplace(_Args&&... __args) {
return __impl_.template __emplace<_Ip>(_VSTD::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
_Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
return __impl_.template __emplace<_Ip>(__il, _VSTD::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
_Tp& emplace(_Args&&... __args) {
return __impl_.template __emplace<_Ip>(_VSTD::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
_Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
return __impl_.template __emplace<_Ip>(__il, _VSTD::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
void swap(variant& __that) noexcept(
__all<(is_nothrow_move_constructible_v<_Types> &&
is_nothrow_swappable_v<_Types>)...>::value) {
__impl_.__swap(__that.__impl_);
}
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>(_VSTD::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>(_VSTD::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>(_VSTD::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 _VSTD::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 _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(
_VSTD::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 _VSTD::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 _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(
_VSTD::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)
? _VSTD::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 _VSTD::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 _VSTD::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{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2))), bool>::value,
"the relational operator does not return a type which is implicitly convertible to bool");
return _Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::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 > 17
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 > 17
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 =
(... || _VSTD::__as_variant(__vs).valueless_by_exception());
if (__valueless) {
__throw_bad_variant_access();
}
}
template <
class _Visitor, class... _Vs,
typename = void_t<decltype(_VSTD::__as_variant(std::declval<_Vs>()))...> >
_LIBCPP_HIDE_FROM_ABI
_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
constexpr decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) {
using __variant_detail::__visitation::__variant;
_VSTD::__throw_if_valueless(_VSTD::forward<_Vs>(__vs)...);
return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor),
_VSTD::forward<_Vs>(__vs)...);
}
#if _LIBCPP_STD_VER > 17
template <
class _Rp, class _Visitor, class... _Vs,
typename = void_t<decltype(_VSTD::__as_variant(std::declval<_Vs>()))...> >
_LIBCPP_HIDE_FROM_ABI
_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
constexpr _Rp visit(_Visitor&& __visitor, _Vs&&... __vs) {
using __variant_detail::__visitation::__variant;
_VSTD::__throw_if_valueless(_VSTD::forward<_Vs>(__vs)...);
return __variant::__visit_value<_Rp>(_VSTD::forward<_Visitor>(__visitor),
_VSTD::forward<_Vs>(__vs)...);
}
#endif
template <class... _Types>
_LIBCPP_HIDE_FROM_ABI
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>(_VSTD::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 > 14
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
# include <type_traits>
# include <typeinfo>
# include <utility>
#endif
#endif // _LIBCPP_VARIANT
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