xref: /freebsd/contrib/llvm-project/libcxx/include/variant (revision 349cc55c9796c4596a5b9904cd3281af295f878f)
10b57cec5SDimitry Andric// -*- C++ -*-
2*349cc55cSDimitry Andric//===----------------------------------------------------------------------===//
30b57cec5SDimitry Andric//
40b57cec5SDimitry Andric// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
50b57cec5SDimitry Andric// See https://llvm.org/LICENSE.txt for license information.
60b57cec5SDimitry Andric// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
70b57cec5SDimitry Andric//
80b57cec5SDimitry Andric//===----------------------------------------------------------------------===//
90b57cec5SDimitry Andric
100b57cec5SDimitry Andric#ifndef _LIBCPP_VARIANT
110b57cec5SDimitry Andric#define _LIBCPP_VARIANT
120b57cec5SDimitry Andric
130b57cec5SDimitry Andric/*
140b57cec5SDimitry Andric   variant synopsis
150b57cec5SDimitry Andric
160b57cec5SDimitry Andricnamespace std {
170b57cec5SDimitry Andric
180b57cec5SDimitry Andric  // 20.7.2, class template variant
190b57cec5SDimitry Andric  template <class... Types>
200b57cec5SDimitry Andric  class variant {
210b57cec5SDimitry Andric  public:
220b57cec5SDimitry Andric
230b57cec5SDimitry Andric    // 20.7.2.1, constructors
240b57cec5SDimitry Andric    constexpr variant() noexcept(see below);
250b57cec5SDimitry Andric    variant(const variant&);                // constexpr in C++20
260b57cec5SDimitry Andric    variant(variant&&) noexcept(see below); // constexpr in C++20
270b57cec5SDimitry Andric
280b57cec5SDimitry Andric    template <class T> constexpr variant(T&&) noexcept(see below);
290b57cec5SDimitry Andric
300b57cec5SDimitry Andric    template <class T, class... Args>
310b57cec5SDimitry Andric    constexpr explicit variant(in_place_type_t<T>, Args&&...);
320b57cec5SDimitry Andric
330b57cec5SDimitry Andric    template <class T, class U, class... Args>
340b57cec5SDimitry Andric    constexpr explicit variant(
350b57cec5SDimitry Andric        in_place_type_t<T>, initializer_list<U>, Args&&...);
360b57cec5SDimitry Andric
370b57cec5SDimitry Andric    template <size_t I, class... Args>
380b57cec5SDimitry Andric    constexpr explicit variant(in_place_index_t<I>, Args&&...);
390b57cec5SDimitry Andric
400b57cec5SDimitry Andric    template <size_t I, class U, class... Args>
410b57cec5SDimitry Andric    constexpr explicit variant(
420b57cec5SDimitry Andric        in_place_index_t<I>, initializer_list<U>, Args&&...);
430b57cec5SDimitry Andric
440b57cec5SDimitry Andric    // 20.7.2.2, destructor
450b57cec5SDimitry Andric    ~variant();
460b57cec5SDimitry Andric
470b57cec5SDimitry Andric    // 20.7.2.3, assignment
480b57cec5SDimitry Andric    variant& operator=(const variant&);                // constexpr in C++20
490b57cec5SDimitry Andric    variant& operator=(variant&&) noexcept(see below); // constexpr in C++20
500b57cec5SDimitry Andric
510b57cec5SDimitry Andric    template <class T> variant& operator=(T&&) noexcept(see below);
520b57cec5SDimitry Andric
530b57cec5SDimitry Andric    // 20.7.2.4, modifiers
540b57cec5SDimitry Andric    template <class T, class... Args>
550b57cec5SDimitry Andric    T& emplace(Args&&...);
560b57cec5SDimitry Andric
570b57cec5SDimitry Andric    template <class T, class U, class... Args>
580b57cec5SDimitry Andric    T& emplace(initializer_list<U>, Args&&...);
590b57cec5SDimitry Andric
600b57cec5SDimitry Andric    template <size_t I, class... Args>
610b57cec5SDimitry Andric    variant_alternative_t<I, variant>& emplace(Args&&...);
620b57cec5SDimitry Andric
630b57cec5SDimitry Andric    template <size_t I, class U, class...  Args>
640b57cec5SDimitry Andric    variant_alternative_t<I, variant>& emplace(initializer_list<U>, Args&&...);
650b57cec5SDimitry Andric
660b57cec5SDimitry Andric    // 20.7.2.5, value status
670b57cec5SDimitry Andric    constexpr bool valueless_by_exception() const noexcept;
680b57cec5SDimitry Andric    constexpr size_t index() const noexcept;
690b57cec5SDimitry Andric
700b57cec5SDimitry Andric    // 20.7.2.6, swap
710b57cec5SDimitry Andric    void swap(variant&) noexcept(see below);
720b57cec5SDimitry Andric  };
730b57cec5SDimitry Andric
740b57cec5SDimitry Andric  // 20.7.3, variant helper classes
750b57cec5SDimitry Andric  template <class T> struct variant_size; // undefined
760b57cec5SDimitry Andric
770b57cec5SDimitry Andric  template <class T>
780b57cec5SDimitry Andric  inline constexpr size_t variant_size_v = variant_size<T>::value;
790b57cec5SDimitry Andric
800b57cec5SDimitry Andric  template <class T> struct variant_size<const T>;
810b57cec5SDimitry Andric  template <class T> struct variant_size<volatile T>;
820b57cec5SDimitry Andric  template <class T> struct variant_size<const volatile T>;
830b57cec5SDimitry Andric
840b57cec5SDimitry Andric  template <class... Types>
850b57cec5SDimitry Andric  struct variant_size<variant<Types...>>;
860b57cec5SDimitry Andric
870b57cec5SDimitry Andric  template <size_t I, class T> struct variant_alternative; // undefined
880b57cec5SDimitry Andric
890b57cec5SDimitry Andric  template <size_t I, class T>
900b57cec5SDimitry Andric  using variant_alternative_t = typename variant_alternative<I, T>::type;
910b57cec5SDimitry Andric
920b57cec5SDimitry Andric  template <size_t I, class T> struct variant_alternative<I, const T>;
930b57cec5SDimitry Andric  template <size_t I, class T> struct variant_alternative<I, volatile T>;
940b57cec5SDimitry Andric  template <size_t I, class T> struct variant_alternative<I, const volatile T>;
950b57cec5SDimitry Andric
960b57cec5SDimitry Andric  template <size_t I, class... Types>
970b57cec5SDimitry Andric  struct variant_alternative<I, variant<Types...>>;
980b57cec5SDimitry Andric
990b57cec5SDimitry Andric  inline constexpr size_t variant_npos = -1;
1000b57cec5SDimitry Andric
1010b57cec5SDimitry Andric  // 20.7.4, value access
1020b57cec5SDimitry Andric  template <class T, class... Types>
1030b57cec5SDimitry Andric  constexpr bool holds_alternative(const variant<Types...>&) noexcept;
1040b57cec5SDimitry Andric
1050b57cec5SDimitry Andric  template <size_t I, class... Types>
1060b57cec5SDimitry Andric  constexpr variant_alternative_t<I, variant<Types...>>&
1070b57cec5SDimitry Andric  get(variant<Types...>&);
1080b57cec5SDimitry Andric
1090b57cec5SDimitry Andric  template <size_t I, class... Types>
1100b57cec5SDimitry Andric  constexpr variant_alternative_t<I, variant<Types...>>&&
1110b57cec5SDimitry Andric  get(variant<Types...>&&);
1120b57cec5SDimitry Andric
1130b57cec5SDimitry Andric  template <size_t I, class... Types>
1140b57cec5SDimitry Andric  constexpr variant_alternative_t<I, variant<Types...>> const&
1150b57cec5SDimitry Andric  get(const variant<Types...>&);
1160b57cec5SDimitry Andric
1170b57cec5SDimitry Andric  template <size_t I, class... Types>
1180b57cec5SDimitry Andric  constexpr variant_alternative_t<I, variant<Types...>> const&&
1190b57cec5SDimitry Andric  get(const variant<Types...>&&);
1200b57cec5SDimitry Andric
1210b57cec5SDimitry Andric  template <class T, class...  Types>
1220b57cec5SDimitry Andric  constexpr T& get(variant<Types...>&);
1230b57cec5SDimitry Andric
1240b57cec5SDimitry Andric  template <class T, class... Types>
1250b57cec5SDimitry Andric  constexpr T&& get(variant<Types...>&&);
1260b57cec5SDimitry Andric
1270b57cec5SDimitry Andric  template <class T, class... Types>
1280b57cec5SDimitry Andric  constexpr const T& get(const variant<Types...>&);
1290b57cec5SDimitry Andric
1300b57cec5SDimitry Andric  template <class T, class... Types>
1310b57cec5SDimitry Andric  constexpr const T&& get(const variant<Types...>&&);
1320b57cec5SDimitry Andric
1330b57cec5SDimitry Andric  template <size_t I, class... Types>
1340b57cec5SDimitry Andric  constexpr add_pointer_t<variant_alternative_t<I, variant<Types...>>>
1350b57cec5SDimitry Andric  get_if(variant<Types...>*) noexcept;
1360b57cec5SDimitry Andric
1370b57cec5SDimitry Andric  template <size_t I, class... Types>
1380b57cec5SDimitry Andric  constexpr add_pointer_t<const variant_alternative_t<I, variant<Types...>>>
1390b57cec5SDimitry Andric  get_if(const variant<Types...>*) noexcept;
1400b57cec5SDimitry Andric
1410b57cec5SDimitry Andric  template <class T, class... Types>
1420b57cec5SDimitry Andric  constexpr add_pointer_t<T>
1430b57cec5SDimitry Andric  get_if(variant<Types...>*) noexcept;
1440b57cec5SDimitry Andric
1450b57cec5SDimitry Andric  template <class T, class... Types>
1460b57cec5SDimitry Andric  constexpr add_pointer_t<const T>
1470b57cec5SDimitry Andric  get_if(const variant<Types...>*) noexcept;
1480b57cec5SDimitry Andric
1490b57cec5SDimitry Andric  // 20.7.5, relational operators
1500b57cec5SDimitry Andric  template <class... Types>
1510b57cec5SDimitry Andric  constexpr bool operator==(const variant<Types...>&, const variant<Types...>&);
1520b57cec5SDimitry Andric
1530b57cec5SDimitry Andric  template <class... Types>
1540b57cec5SDimitry Andric  constexpr bool operator!=(const variant<Types...>&, const variant<Types...>&);
1550b57cec5SDimitry Andric
1560b57cec5SDimitry Andric  template <class... Types>
1570b57cec5SDimitry Andric  constexpr bool operator<(const variant<Types...>&, const variant<Types...>&);
1580b57cec5SDimitry Andric
1590b57cec5SDimitry Andric  template <class... Types>
1600b57cec5SDimitry Andric  constexpr bool operator>(const variant<Types...>&, const variant<Types...>&);
1610b57cec5SDimitry Andric
1620b57cec5SDimitry Andric  template <class... Types>
1630b57cec5SDimitry Andric  constexpr bool operator<=(const variant<Types...>&, const variant<Types...>&);
1640b57cec5SDimitry Andric
1650b57cec5SDimitry Andric  template <class... Types>
1660b57cec5SDimitry Andric  constexpr bool operator>=(const variant<Types...>&, const variant<Types...>&);
1670b57cec5SDimitry Andric
1680b57cec5SDimitry Andric  // 20.7.6, visitation
1690b57cec5SDimitry Andric  template <class Visitor, class... Variants>
1700b57cec5SDimitry Andric  constexpr see below visit(Visitor&&, Variants&&...);
1710b57cec5SDimitry Andric
172e8d8bef9SDimitry Andric  template <class R, class Visitor, class... Variants>
173e8d8bef9SDimitry Andric  constexpr R visit(Visitor&&, Variants&&...); // since C++20
174e8d8bef9SDimitry Andric
1750b57cec5SDimitry Andric  // 20.7.7, class monostate
1760b57cec5SDimitry Andric  struct monostate;
1770b57cec5SDimitry Andric
1780b57cec5SDimitry Andric  // 20.7.8, monostate relational operators
1790b57cec5SDimitry Andric  constexpr bool operator<(monostate, monostate) noexcept;
1800b57cec5SDimitry Andric  constexpr bool operator>(monostate, monostate) noexcept;
1810b57cec5SDimitry Andric  constexpr bool operator<=(monostate, monostate) noexcept;
1820b57cec5SDimitry Andric  constexpr bool operator>=(monostate, monostate) noexcept;
1830b57cec5SDimitry Andric  constexpr bool operator==(monostate, monostate) noexcept;
1840b57cec5SDimitry Andric  constexpr bool operator!=(monostate, monostate) noexcept;
1850b57cec5SDimitry Andric
1860b57cec5SDimitry Andric  // 20.7.9, specialized algorithms
1870b57cec5SDimitry Andric  template <class... Types>
1880b57cec5SDimitry Andric  void swap(variant<Types...>&, variant<Types...>&) noexcept(see below);
1890b57cec5SDimitry Andric
1900b57cec5SDimitry Andric  // 20.7.10, class bad_variant_access
1910b57cec5SDimitry Andric  class bad_variant_access;
1920b57cec5SDimitry Andric
1930b57cec5SDimitry Andric  // 20.7.11, hash support
1940b57cec5SDimitry Andric  template <class T> struct hash;
1950b57cec5SDimitry Andric  template <class... Types> struct hash<variant<Types...>>;
1960b57cec5SDimitry Andric  template <> struct hash<monostate>;
1970b57cec5SDimitry Andric
1980b57cec5SDimitry Andric} // namespace std
1990b57cec5SDimitry Andric
2000b57cec5SDimitry Andric*/
2010b57cec5SDimitry Andric
202e8d8bef9SDimitry Andric#include <__availability>
203fe6060f1SDimitry Andric#include <__config>
204fe6060f1SDimitry Andric#include <__functional/hash.h>
2050b57cec5SDimitry Andric#include <__tuple>
206fe6060f1SDimitry Andric#include <__utility/forward.h>
207fe6060f1SDimitry Andric#include <__variant/monostate.h>
208fe6060f1SDimitry Andric#include <compare>
2090b57cec5SDimitry Andric#include <exception>
2100b57cec5SDimitry Andric#include <initializer_list>
211fe6060f1SDimitry Andric#include <limits>
2120b57cec5SDimitry Andric#include <new>
2130b57cec5SDimitry Andric#include <tuple>
2140b57cec5SDimitry Andric#include <type_traits>
2150b57cec5SDimitry Andric#include <utility>
2160b57cec5SDimitry Andric#include <version>
2170b57cec5SDimitry Andric
2180b57cec5SDimitry Andric#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
2190b57cec5SDimitry Andric#pragma GCC system_header
2200b57cec5SDimitry Andric#endif
2210b57cec5SDimitry Andric
2220b57cec5SDimitry Andric_LIBCPP_PUSH_MACROS
2230b57cec5SDimitry Andric#include <__undef_macros>
2240b57cec5SDimitry Andric
2250b57cec5SDimitry Andricnamespace std { // explicitly not using versioning namespace
2260b57cec5SDimitry Andric
2270b57cec5SDimitry Andricclass _LIBCPP_EXCEPTION_ABI _LIBCPP_AVAILABILITY_BAD_VARIANT_ACCESS bad_variant_access : public exception {
2280b57cec5SDimitry Andricpublic:
2290b57cec5SDimitry Andric  virtual const char* what() const _NOEXCEPT;
2300b57cec5SDimitry Andric};
2310b57cec5SDimitry Andric
2320b57cec5SDimitry Andric} // namespace std
2330b57cec5SDimitry Andric
2340b57cec5SDimitry Andric_LIBCPP_BEGIN_NAMESPACE_STD
2350b57cec5SDimitry Andric
236*349cc55cSDimitry Andric#if _LIBCPP_STD_VER > 14
2370b57cec5SDimitry Andric
238fe6060f1SDimitry Andric// Light N-dimensional array of function pointers. Used in place of std::array to avoid
239fe6060f1SDimitry Andric// adding a dependency.
240fe6060f1SDimitry Andrictemplate<class _Tp, size_t _Size>
241fe6060f1SDimitry Andricstruct __farray {
242fe6060f1SDimitry Andric  static_assert(_Size > 0, "N-dimensional array should never be empty in std::visit");
243fe6060f1SDimitry Andric  _Tp __buf_[_Size] = {};
244fe6060f1SDimitry Andric
245fe6060f1SDimitry Andric  _LIBCPP_INLINE_VISIBILITY constexpr
246fe6060f1SDimitry Andric  const _Tp &operator[](size_t __n) const noexcept {
247fe6060f1SDimitry Andric      return __buf_[__n];
248fe6060f1SDimitry Andric  }
249fe6060f1SDimitry Andric};
250fe6060f1SDimitry Andric
2510b57cec5SDimitry Andric_LIBCPP_NORETURN
2520b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
2530b57cec5SDimitry Andric_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
2540b57cec5SDimitry Andricvoid __throw_bad_variant_access() {
2550b57cec5SDimitry Andric#ifndef _LIBCPP_NO_EXCEPTIONS
2560b57cec5SDimitry Andric        throw bad_variant_access();
2570b57cec5SDimitry Andric#else
2580b57cec5SDimitry Andric        _VSTD::abort();
2590b57cec5SDimitry Andric#endif
2600b57cec5SDimitry Andric}
2610b57cec5SDimitry Andric
2620b57cec5SDimitry Andrictemplate <class... _Types>
2630b57cec5SDimitry Andricclass _LIBCPP_TEMPLATE_VIS variant;
2640b57cec5SDimitry Andric
2650b57cec5SDimitry Andrictemplate <class _Tp>
2660b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS variant_size;
2670b57cec5SDimitry Andric
2680b57cec5SDimitry Andrictemplate <class _Tp>
269*349cc55cSDimitry Andricinline constexpr size_t variant_size_v = variant_size<_Tp>::value;
2700b57cec5SDimitry Andric
2710b57cec5SDimitry Andrictemplate <class _Tp>
2720b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS variant_size<const _Tp> : variant_size<_Tp> {};
2730b57cec5SDimitry Andric
2740b57cec5SDimitry Andrictemplate <class _Tp>
2750b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS variant_size<volatile _Tp> : variant_size<_Tp> {};
2760b57cec5SDimitry Andric
2770b57cec5SDimitry Andrictemplate <class _Tp>
2780b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS variant_size<const volatile _Tp>
2790b57cec5SDimitry Andric    : variant_size<_Tp> {};
2800b57cec5SDimitry Andric
2810b57cec5SDimitry Andrictemplate <class... _Types>
2820b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS variant_size<variant<_Types...>>
2830b57cec5SDimitry Andric    : integral_constant<size_t, sizeof...(_Types)> {};
2840b57cec5SDimitry Andric
2850b57cec5SDimitry Andrictemplate <size_t _Ip, class _Tp>
2860b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS variant_alternative;
2870b57cec5SDimitry Andric
2880b57cec5SDimitry Andrictemplate <size_t _Ip, class _Tp>
2890b57cec5SDimitry Andricusing variant_alternative_t = typename variant_alternative<_Ip, _Tp>::type;
2900b57cec5SDimitry Andric
2910b57cec5SDimitry Andrictemplate <size_t _Ip, class _Tp>
2920b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const _Tp>
2930b57cec5SDimitry Andric    : add_const<variant_alternative_t<_Ip, _Tp>> {};
2940b57cec5SDimitry Andric
2950b57cec5SDimitry Andrictemplate <size_t _Ip, class _Tp>
2960b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, volatile _Tp>
2970b57cec5SDimitry Andric    : add_volatile<variant_alternative_t<_Ip, _Tp>> {};
2980b57cec5SDimitry Andric
2990b57cec5SDimitry Andrictemplate <size_t _Ip, class _Tp>
3000b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, const volatile _Tp>
3010b57cec5SDimitry Andric    : add_cv<variant_alternative_t<_Ip, _Tp>> {};
3020b57cec5SDimitry Andric
3030b57cec5SDimitry Andrictemplate <size_t _Ip, class... _Types>
3040b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS variant_alternative<_Ip, variant<_Types...>> {
3050b57cec5SDimitry Andric  static_assert(_Ip < sizeof...(_Types), "Index out of bounds in std::variant_alternative<>");
3060b57cec5SDimitry Andric  using type = __type_pack_element<_Ip, _Types...>;
3070b57cec5SDimitry Andric};
3080b57cec5SDimitry Andric
309*349cc55cSDimitry Andricinline constexpr size_t variant_npos = static_cast<size_t>(-1);
3100b57cec5SDimitry Andric
3110b57cec5SDimitry Andricconstexpr int __choose_index_type(unsigned int __num_elem) {
312e8d8bef9SDimitry Andric  if (__num_elem < numeric_limits<unsigned char>::max())
3130b57cec5SDimitry Andric    return 0;
314e8d8bef9SDimitry Andric  if (__num_elem < numeric_limits<unsigned short>::max())
3150b57cec5SDimitry Andric    return 1;
3160b57cec5SDimitry Andric  return 2;
3170b57cec5SDimitry Andric}
3180b57cec5SDimitry Andric
3190b57cec5SDimitry Andrictemplate <size_t _NumAlts>
3200b57cec5SDimitry Andricusing __variant_index_t =
3210b57cec5SDimitry Andric#ifndef _LIBCPP_ABI_VARIANT_INDEX_TYPE_OPTIMIZATION
3220b57cec5SDimitry Andric  unsigned int;
3230b57cec5SDimitry Andric#else
3240b57cec5SDimitry Andric  std::tuple_element_t<
3250b57cec5SDimitry Andric      __choose_index_type(_NumAlts),
3260b57cec5SDimitry Andric      std::tuple<unsigned char, unsigned short, unsigned int>
3270b57cec5SDimitry Andric  >;
3280b57cec5SDimitry Andric#endif
3290b57cec5SDimitry Andric
3300b57cec5SDimitry Andrictemplate <class _IndexType>
3310b57cec5SDimitry Andricconstexpr _IndexType __variant_npos = static_cast<_IndexType>(-1);
3320b57cec5SDimitry Andric
333fe6060f1SDimitry Andrictemplate <class... _Types>
334fe6060f1SDimitry Andricclass _LIBCPP_TEMPLATE_VIS variant;
335fe6060f1SDimitry Andric
336fe6060f1SDimitry Andrictemplate <class... _Types>
337fe6060f1SDimitry Andric_LIBCPP_INLINE_VISIBILITY constexpr variant<_Types...>&
338fe6060f1SDimitry Andric__as_variant(variant<_Types...>& __vs) noexcept {
339fe6060f1SDimitry Andric  return __vs;
340fe6060f1SDimitry Andric}
341fe6060f1SDimitry Andric
342fe6060f1SDimitry Andrictemplate <class... _Types>
343fe6060f1SDimitry Andric_LIBCPP_INLINE_VISIBILITY constexpr const variant<_Types...>&
344fe6060f1SDimitry Andric__as_variant(const variant<_Types...>& __vs) noexcept {
345fe6060f1SDimitry Andric  return __vs;
346fe6060f1SDimitry Andric}
347fe6060f1SDimitry Andric
348fe6060f1SDimitry Andrictemplate <class... _Types>
349fe6060f1SDimitry Andric_LIBCPP_INLINE_VISIBILITY constexpr variant<_Types...>&&
350fe6060f1SDimitry Andric__as_variant(variant<_Types...>&& __vs) noexcept {
351fe6060f1SDimitry Andric  return _VSTD::move(__vs);
352fe6060f1SDimitry Andric}
353fe6060f1SDimitry Andric
354fe6060f1SDimitry Andrictemplate <class... _Types>
355fe6060f1SDimitry Andric_LIBCPP_INLINE_VISIBILITY constexpr const variant<_Types...>&&
356fe6060f1SDimitry Andric__as_variant(const variant<_Types...>&& __vs) noexcept {
357fe6060f1SDimitry Andric  return _VSTD::move(__vs);
358fe6060f1SDimitry Andric}
359fe6060f1SDimitry Andric
3600b57cec5SDimitry Andricnamespace __find_detail {
3610b57cec5SDimitry Andric
3620b57cec5SDimitry Andrictemplate <class _Tp, class... _Types>
3630b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
3640b57cec5SDimitry Andricconstexpr size_t __find_index() {
3650b57cec5SDimitry Andric  constexpr bool __matches[] = {is_same_v<_Tp, _Types>...};
3660b57cec5SDimitry Andric  size_t __result = __not_found;
3670b57cec5SDimitry Andric  for (size_t __i = 0; __i < sizeof...(_Types); ++__i) {
3680b57cec5SDimitry Andric    if (__matches[__i]) {
3690b57cec5SDimitry Andric      if (__result != __not_found) {
3700b57cec5SDimitry Andric        return __ambiguous;
3710b57cec5SDimitry Andric      }
3720b57cec5SDimitry Andric      __result = __i;
3730b57cec5SDimitry Andric    }
3740b57cec5SDimitry Andric  }
3750b57cec5SDimitry Andric  return __result;
3760b57cec5SDimitry Andric}
3770b57cec5SDimitry Andric
3780b57cec5SDimitry Andrictemplate <size_t _Index>
3790b57cec5SDimitry Andricstruct __find_unambiguous_index_sfinae_impl
3800b57cec5SDimitry Andric    : integral_constant<size_t, _Index> {};
3810b57cec5SDimitry Andric
3820b57cec5SDimitry Andrictemplate <>
3830b57cec5SDimitry Andricstruct __find_unambiguous_index_sfinae_impl<__not_found> {};
3840b57cec5SDimitry Andric
3850b57cec5SDimitry Andrictemplate <>
3860b57cec5SDimitry Andricstruct __find_unambiguous_index_sfinae_impl<__ambiguous> {};
3870b57cec5SDimitry Andric
3880b57cec5SDimitry Andrictemplate <class _Tp, class... _Types>
3890b57cec5SDimitry Andricstruct __find_unambiguous_index_sfinae
3900b57cec5SDimitry Andric    : __find_unambiguous_index_sfinae_impl<__find_index<_Tp, _Types...>()> {};
3910b57cec5SDimitry Andric
3920b57cec5SDimitry Andric} // namespace __find_detail
3930b57cec5SDimitry Andric
3940b57cec5SDimitry Andricnamespace __variant_detail {
3950b57cec5SDimitry Andric
3960b57cec5SDimitry Andricstruct __valueless_t {};
3970b57cec5SDimitry Andric
3980b57cec5SDimitry Andricenum class _Trait { _TriviallyAvailable, _Available, _Unavailable };
3990b57cec5SDimitry Andric
4000b57cec5SDimitry Andrictemplate <typename _Tp,
4010b57cec5SDimitry Andric          template <typename> class _IsTriviallyAvailable,
4020b57cec5SDimitry Andric          template <typename> class _IsAvailable>
4030b57cec5SDimitry Andricconstexpr _Trait __trait =
4040b57cec5SDimitry Andric    _IsTriviallyAvailable<_Tp>::value
4050b57cec5SDimitry Andric        ? _Trait::_TriviallyAvailable
4060b57cec5SDimitry Andric        : _IsAvailable<_Tp>::value ? _Trait::_Available : _Trait::_Unavailable;
4070b57cec5SDimitry Andric
4080b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
4090b57cec5SDimitry Andricconstexpr _Trait __common_trait(initializer_list<_Trait> __traits) {
4100b57cec5SDimitry Andric  _Trait __result = _Trait::_TriviallyAvailable;
4110b57cec5SDimitry Andric  for (_Trait __t : __traits) {
4120b57cec5SDimitry Andric    if (static_cast<int>(__t) > static_cast<int>(__result)) {
4130b57cec5SDimitry Andric      __result = __t;
4140b57cec5SDimitry Andric    }
4150b57cec5SDimitry Andric  }
4160b57cec5SDimitry Andric  return __result;
4170b57cec5SDimitry Andric}
4180b57cec5SDimitry Andric
4190b57cec5SDimitry Andrictemplate <typename... _Types>
4200b57cec5SDimitry Andricstruct __traits {
4210b57cec5SDimitry Andric  static constexpr _Trait __copy_constructible_trait =
4220b57cec5SDimitry Andric      __common_trait({__trait<_Types,
4230b57cec5SDimitry Andric                              is_trivially_copy_constructible,
4240b57cec5SDimitry Andric                              is_copy_constructible>...});
4250b57cec5SDimitry Andric
4260b57cec5SDimitry Andric  static constexpr _Trait __move_constructible_trait =
4270b57cec5SDimitry Andric      __common_trait({__trait<_Types,
4280b57cec5SDimitry Andric                              is_trivially_move_constructible,
4290b57cec5SDimitry Andric                              is_move_constructible>...});
4300b57cec5SDimitry Andric
4310b57cec5SDimitry Andric  static constexpr _Trait __copy_assignable_trait = __common_trait(
4320b57cec5SDimitry Andric      {__copy_constructible_trait,
4330b57cec5SDimitry Andric       __trait<_Types, is_trivially_copy_assignable, is_copy_assignable>...});
4340b57cec5SDimitry Andric
4350b57cec5SDimitry Andric  static constexpr _Trait __move_assignable_trait = __common_trait(
4360b57cec5SDimitry Andric      {__move_constructible_trait,
4370b57cec5SDimitry Andric       __trait<_Types, is_trivially_move_assignable, is_move_assignable>...});
4380b57cec5SDimitry Andric
4390b57cec5SDimitry Andric  static constexpr _Trait __destructible_trait = __common_trait(
4400b57cec5SDimitry Andric      {__trait<_Types, is_trivially_destructible, is_destructible>...});
4410b57cec5SDimitry Andric};
4420b57cec5SDimitry Andric
4430b57cec5SDimitry Andricnamespace __access {
4440b57cec5SDimitry Andric
4450b57cec5SDimitry Andricstruct __union {
4460b57cec5SDimitry Andric  template <class _Vp>
4470b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
4480b57cec5SDimitry Andric  static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<0>) {
4490b57cec5SDimitry Andric    return _VSTD::forward<_Vp>(__v).__head;
4500b57cec5SDimitry Andric  }
4510b57cec5SDimitry Andric
4520b57cec5SDimitry Andric  template <class _Vp, size_t _Ip>
4530b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
4540b57cec5SDimitry Andric  static constexpr auto&& __get_alt(_Vp&& __v, in_place_index_t<_Ip>) {
4550b57cec5SDimitry Andric    return __get_alt(_VSTD::forward<_Vp>(__v).__tail, in_place_index<_Ip - 1>);
4560b57cec5SDimitry Andric  }
4570b57cec5SDimitry Andric};
4580b57cec5SDimitry Andric
4590b57cec5SDimitry Andricstruct __base {
4600b57cec5SDimitry Andric  template <size_t _Ip, class _Vp>
4610b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
4620b57cec5SDimitry Andric  static constexpr auto&& __get_alt(_Vp&& __v) {
4630b57cec5SDimitry Andric    return __union::__get_alt(_VSTD::forward<_Vp>(__v).__data,
4640b57cec5SDimitry Andric                              in_place_index<_Ip>);
4650b57cec5SDimitry Andric  }
4660b57cec5SDimitry Andric};
4670b57cec5SDimitry Andric
4680b57cec5SDimitry Andricstruct __variant {
4690b57cec5SDimitry Andric  template <size_t _Ip, class _Vp>
4700b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
4710b57cec5SDimitry Andric  static constexpr auto&& __get_alt(_Vp&& __v) {
4720b57cec5SDimitry Andric    return __base::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v).__impl);
4730b57cec5SDimitry Andric  }
4740b57cec5SDimitry Andric};
4750b57cec5SDimitry Andric
4760b57cec5SDimitry Andric} // namespace __access
4770b57cec5SDimitry Andric
4780b57cec5SDimitry Andricnamespace __visitation {
4790b57cec5SDimitry Andric
4800b57cec5SDimitry Andricstruct __base {
4810b57cec5SDimitry Andric  template <class _Visitor, class... _Vs>
4820b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
4830b57cec5SDimitry Andric  static constexpr decltype(auto)
4840b57cec5SDimitry Andric  __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
4850b57cec5SDimitry Andric    constexpr auto __fdiagonal =
4860b57cec5SDimitry Andric        __make_fdiagonal<_Visitor&&,
4870b57cec5SDimitry Andric                         decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
4880b57cec5SDimitry Andric    return __fdiagonal[__index](_VSTD::forward<_Visitor>(__visitor),
4890b57cec5SDimitry Andric                                _VSTD::forward<_Vs>(__vs).__as_base()...);
4900b57cec5SDimitry Andric  }
4910b57cec5SDimitry Andric
4920b57cec5SDimitry Andric  template <class _Visitor, class... _Vs>
4930b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
4940b57cec5SDimitry Andric  static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
4950b57cec5SDimitry Andric                                              _Vs&&... __vs) {
4960b57cec5SDimitry Andric    constexpr auto __fmatrix =
4970b57cec5SDimitry Andric        __make_fmatrix<_Visitor&&,
4980b57cec5SDimitry Andric                       decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
4990b57cec5SDimitry Andric    return __at(__fmatrix, __vs.index()...)(
5000b57cec5SDimitry Andric        _VSTD::forward<_Visitor>(__visitor),
5010b57cec5SDimitry Andric        _VSTD::forward<_Vs>(__vs).__as_base()...);
5020b57cec5SDimitry Andric  }
5030b57cec5SDimitry Andric
5040b57cec5SDimitry Andricprivate:
5050b57cec5SDimitry Andric  template <class _Tp>
5060b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
5070b57cec5SDimitry Andric  static constexpr const _Tp& __at(const _Tp& __elem) { return __elem; }
5080b57cec5SDimitry Andric
5090b57cec5SDimitry Andric  template <class _Tp, size_t _Np, typename... _Indices>
5100b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
511fe6060f1SDimitry Andric  static constexpr auto&& __at(const __farray<_Tp, _Np>& __elems,
5120b57cec5SDimitry Andric                               size_t __index, _Indices... __indices) {
5130b57cec5SDimitry Andric    return __at(__elems[__index], __indices...);
5140b57cec5SDimitry Andric  }
5150b57cec5SDimitry Andric
5160b57cec5SDimitry Andric  template <class _Fp, class... _Fs>
5170b57cec5SDimitry Andric  static constexpr void __std_visit_visitor_return_type_check() {
5180b57cec5SDimitry Andric    static_assert(
5190b57cec5SDimitry Andric        __all<is_same_v<_Fp, _Fs>...>::value,
5200b57cec5SDimitry Andric        "`std::visit` requires the visitor to have a single return type.");
5210b57cec5SDimitry Andric  }
5220b57cec5SDimitry Andric
5230b57cec5SDimitry Andric  template <class... _Fs>
5240b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
5250b57cec5SDimitry Andric  static constexpr auto __make_farray(_Fs&&... __fs) {
5260b57cec5SDimitry Andric    __std_visit_visitor_return_type_check<__uncvref_t<_Fs>...>();
527fe6060f1SDimitry Andric    using __result = __farray<common_type_t<__uncvref_t<_Fs>...>, sizeof...(_Fs)>;
5280b57cec5SDimitry Andric    return __result{{_VSTD::forward<_Fs>(__fs)...}};
5290b57cec5SDimitry Andric  }
5300b57cec5SDimitry Andric
531e8d8bef9SDimitry Andric  template <size_t... _Is>
5320b57cec5SDimitry Andric  struct __dispatcher {
5330b57cec5SDimitry Andric    template <class _Fp, class... _Vs>
5340b57cec5SDimitry Andric    inline _LIBCPP_INLINE_VISIBILITY
5350b57cec5SDimitry Andric    static constexpr decltype(auto) __dispatch(_Fp __f, _Vs... __vs) {
536e8d8bef9SDimitry Andric        return _VSTD::__invoke_constexpr(
5370b57cec5SDimitry Andric            static_cast<_Fp>(__f),
5380b57cec5SDimitry Andric            __access::__base::__get_alt<_Is>(static_cast<_Vs>(__vs))...);
5390b57cec5SDimitry Andric    }
5400b57cec5SDimitry Andric  };
5410b57cec5SDimitry Andric
5420b57cec5SDimitry Andric  template <class _Fp, class... _Vs, size_t... _Is>
5430b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
5440b57cec5SDimitry Andric  static constexpr auto __make_dispatch(index_sequence<_Is...>) {
5450b57cec5SDimitry Andric    return __dispatcher<_Is...>::template __dispatch<_Fp, _Vs...>;
5460b57cec5SDimitry Andric  }
5470b57cec5SDimitry Andric
5480b57cec5SDimitry Andric  template <size_t _Ip, class _Fp, class... _Vs>
5490b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
5500b57cec5SDimitry Andric  static constexpr auto __make_fdiagonal_impl() {
5510b57cec5SDimitry Andric    return __make_dispatch<_Fp, _Vs...>(
552*349cc55cSDimitry Andric        index_sequence<((void)__identity<_Vs>{}, _Ip)...>{});
5530b57cec5SDimitry Andric  }
5540b57cec5SDimitry Andric
5550b57cec5SDimitry Andric  template <class _Fp, class... _Vs, size_t... _Is>
5560b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
5570b57cec5SDimitry Andric  static constexpr auto __make_fdiagonal_impl(index_sequence<_Is...>) {
5580b57cec5SDimitry Andric    return __base::__make_farray(__make_fdiagonal_impl<_Is, _Fp, _Vs...>()...);
5590b57cec5SDimitry Andric  }
5600b57cec5SDimitry Andric
5610b57cec5SDimitry Andric  template <class _Fp, class _Vp, class... _Vs>
5620b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
5630b57cec5SDimitry Andric  static constexpr auto __make_fdiagonal() {
5640b57cec5SDimitry Andric    constexpr size_t _Np = __uncvref_t<_Vp>::__size();
5650b57cec5SDimitry Andric    static_assert(__all<(_Np == __uncvref_t<_Vs>::__size())...>::value);
5660b57cec5SDimitry Andric    return __make_fdiagonal_impl<_Fp, _Vp, _Vs...>(make_index_sequence<_Np>{});
5670b57cec5SDimitry Andric  }
5680b57cec5SDimitry Andric
5690b57cec5SDimitry Andric  template <class _Fp, class... _Vs, size_t... _Is>
5700b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
5710b57cec5SDimitry Andric  static constexpr auto __make_fmatrix_impl(index_sequence<_Is...> __is) {
5720b57cec5SDimitry Andric    return __make_dispatch<_Fp, _Vs...>(__is);
5730b57cec5SDimitry Andric  }
5740b57cec5SDimitry Andric
5750b57cec5SDimitry Andric  template <class _Fp, class... _Vs, size_t... _Is, size_t... _Js, class... _Ls>
5760b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
5770b57cec5SDimitry Andric  static constexpr auto __make_fmatrix_impl(index_sequence<_Is...>,
5780b57cec5SDimitry Andric                                            index_sequence<_Js...>,
5790b57cec5SDimitry Andric                                            _Ls... __ls) {
5800b57cec5SDimitry Andric    return __base::__make_farray(__make_fmatrix_impl<_Fp, _Vs...>(
5810b57cec5SDimitry Andric        index_sequence<_Is..., _Js>{}, __ls...)...);
5820b57cec5SDimitry Andric  }
5830b57cec5SDimitry Andric
5840b57cec5SDimitry Andric  template <class _Fp, class... _Vs>
5850b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
5860b57cec5SDimitry Andric  static constexpr auto __make_fmatrix() {
5870b57cec5SDimitry Andric    return __make_fmatrix_impl<_Fp, _Vs...>(
5880b57cec5SDimitry Andric        index_sequence<>{}, make_index_sequence<__uncvref_t<_Vs>::__size()>{}...);
5890b57cec5SDimitry Andric  }
5900b57cec5SDimitry Andric};
5910b57cec5SDimitry Andric
5920b57cec5SDimitry Andricstruct __variant {
5930b57cec5SDimitry Andric  template <class _Visitor, class... _Vs>
5940b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
5950b57cec5SDimitry Andric  static constexpr decltype(auto)
5960b57cec5SDimitry Andric  __visit_alt_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
5970b57cec5SDimitry Andric    return __base::__visit_alt_at(__index,
5980b57cec5SDimitry Andric                                  _VSTD::forward<_Visitor>(__visitor),
5990b57cec5SDimitry Andric                                  _VSTD::forward<_Vs>(__vs).__impl...);
6000b57cec5SDimitry Andric  }
6010b57cec5SDimitry Andric
6020b57cec5SDimitry Andric  template <class _Visitor, class... _Vs>
6030b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
6040b57cec5SDimitry Andric  static constexpr decltype(auto) __visit_alt(_Visitor&& __visitor,
6050b57cec5SDimitry Andric                                              _Vs&&... __vs) {
606fe6060f1SDimitry Andric    return __base::__visit_alt(
607fe6060f1SDimitry Andric        _VSTD::forward<_Visitor>(__visitor),
608fe6060f1SDimitry Andric        _VSTD::__as_variant(_VSTD::forward<_Vs>(__vs)).__impl...);
6090b57cec5SDimitry Andric  }
6100b57cec5SDimitry Andric
6110b57cec5SDimitry Andric  template <class _Visitor, class... _Vs>
6120b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
6130b57cec5SDimitry Andric  static constexpr decltype(auto)
6140b57cec5SDimitry Andric  __visit_value_at(size_t __index, _Visitor&& __visitor, _Vs&&... __vs) {
6150b57cec5SDimitry Andric    return __visit_alt_at(
6160b57cec5SDimitry Andric        __index,
6170b57cec5SDimitry Andric        __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
6180b57cec5SDimitry Andric        _VSTD::forward<_Vs>(__vs)...);
6190b57cec5SDimitry Andric  }
6200b57cec5SDimitry Andric
6210b57cec5SDimitry Andric  template <class _Visitor, class... _Vs>
6220b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
6230b57cec5SDimitry Andric  static constexpr decltype(auto) __visit_value(_Visitor&& __visitor,
6240b57cec5SDimitry Andric                                                _Vs&&... __vs) {
6250b57cec5SDimitry Andric    return __visit_alt(
6260b57cec5SDimitry Andric        __make_value_visitor(_VSTD::forward<_Visitor>(__visitor)),
6270b57cec5SDimitry Andric        _VSTD::forward<_Vs>(__vs)...);
6280b57cec5SDimitry Andric  }
629fe6060f1SDimitry Andric
630e8d8bef9SDimitry Andric#if _LIBCPP_STD_VER > 17
631e8d8bef9SDimitry Andric  template <class _Rp, class _Visitor, class... _Vs>
632e8d8bef9SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
633e8d8bef9SDimitry Andric  static constexpr _Rp __visit_value(_Visitor&& __visitor,
634e8d8bef9SDimitry Andric                                     _Vs&&... __vs) {
635e8d8bef9SDimitry Andric    return __visit_alt(
636e8d8bef9SDimitry Andric        __make_value_visitor<_Rp>(_VSTD::forward<_Visitor>(__visitor)),
637e8d8bef9SDimitry Andric        _VSTD::forward<_Vs>(__vs)...);
638e8d8bef9SDimitry Andric  }
639e8d8bef9SDimitry Andric#endif
6400b57cec5SDimitry Andric
6410b57cec5SDimitry Andricprivate:
6420b57cec5SDimitry Andric  template <class _Visitor, class... _Values>
6430b57cec5SDimitry Andric  static constexpr void __std_visit_exhaustive_visitor_check() {
6440b57cec5SDimitry Andric    static_assert(is_invocable_v<_Visitor, _Values...>,
6450b57cec5SDimitry Andric                  "`std::visit` requires the visitor to be exhaustive.");
6460b57cec5SDimitry Andric  }
6470b57cec5SDimitry Andric
6480b57cec5SDimitry Andric  template <class _Visitor>
6490b57cec5SDimitry Andric  struct __value_visitor {
6500b57cec5SDimitry Andric    template <class... _Alts>
6510b57cec5SDimitry Andric    inline _LIBCPP_INLINE_VISIBILITY
6520b57cec5SDimitry Andric    constexpr decltype(auto) operator()(_Alts&&... __alts) const {
6530b57cec5SDimitry Andric      __std_visit_exhaustive_visitor_check<
6540b57cec5SDimitry Andric          _Visitor,
6550b57cec5SDimitry Andric          decltype((_VSTD::forward<_Alts>(__alts).__value))...>();
656e8d8bef9SDimitry Andric      return _VSTD::__invoke_constexpr(_VSTD::forward<_Visitor>(__visitor),
6570b57cec5SDimitry Andric                                _VSTD::forward<_Alts>(__alts).__value...);
6580b57cec5SDimitry Andric    }
6590b57cec5SDimitry Andric    _Visitor&& __visitor;
6600b57cec5SDimitry Andric  };
6610b57cec5SDimitry Andric
662e8d8bef9SDimitry Andric#if _LIBCPP_STD_VER > 17
663e8d8bef9SDimitry Andric  template <class _Rp, class _Visitor>
664e8d8bef9SDimitry Andric  struct __value_visitor_return_type {
665e8d8bef9SDimitry Andric    template <class... _Alts>
666e8d8bef9SDimitry Andric    inline _LIBCPP_INLINE_VISIBILITY
667e8d8bef9SDimitry Andric    constexpr _Rp operator()(_Alts&&... __alts) const {
668e8d8bef9SDimitry Andric      __std_visit_exhaustive_visitor_check<
669e8d8bef9SDimitry Andric          _Visitor,
670e8d8bef9SDimitry Andric          decltype((_VSTD::forward<_Alts>(__alts).__value))...>();
671e8d8bef9SDimitry Andric      if constexpr (is_void_v<_Rp>) {
672e8d8bef9SDimitry Andric        _VSTD::__invoke_constexpr(_VSTD::forward<_Visitor>(__visitor),
673e8d8bef9SDimitry Andric                                  _VSTD::forward<_Alts>(__alts).__value...);
674e8d8bef9SDimitry Andric      }
675e8d8bef9SDimitry Andric      else {
676e8d8bef9SDimitry Andric        return _VSTD::__invoke_constexpr(_VSTD::forward<_Visitor>(__visitor),
677e8d8bef9SDimitry Andric                                         _VSTD::forward<_Alts>(__alts).__value...);
678e8d8bef9SDimitry Andric      }
679e8d8bef9SDimitry Andric    }
680e8d8bef9SDimitry Andric
681e8d8bef9SDimitry Andric    _Visitor&& __visitor;
682e8d8bef9SDimitry Andric  };
683e8d8bef9SDimitry Andric#endif
684e8d8bef9SDimitry Andric
6850b57cec5SDimitry Andric  template <class _Visitor>
6860b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
6870b57cec5SDimitry Andric  static constexpr auto __make_value_visitor(_Visitor&& __visitor) {
6880b57cec5SDimitry Andric    return __value_visitor<_Visitor>{_VSTD::forward<_Visitor>(__visitor)};
6890b57cec5SDimitry Andric  }
690e8d8bef9SDimitry Andric
691e8d8bef9SDimitry Andric#if _LIBCPP_STD_VER > 17
692e8d8bef9SDimitry Andric  template <class _Rp, class _Visitor>
693e8d8bef9SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
694e8d8bef9SDimitry Andric  static constexpr auto __make_value_visitor(_Visitor&& __visitor) {
695e8d8bef9SDimitry Andric    return __value_visitor_return_type<_Rp, _Visitor>{_VSTD::forward<_Visitor>(__visitor)};
696e8d8bef9SDimitry Andric  }
697e8d8bef9SDimitry Andric#endif
6980b57cec5SDimitry Andric};
6990b57cec5SDimitry Andric
7000b57cec5SDimitry Andric} // namespace __visitation
7010b57cec5SDimitry Andric
7020b57cec5SDimitry Andrictemplate <size_t _Index, class _Tp>
7030b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS __alt {
7040b57cec5SDimitry Andric  using __value_type = _Tp;
7050b57cec5SDimitry Andric
7060b57cec5SDimitry Andric  template <class... _Args>
7070b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
7080b57cec5SDimitry Andric  explicit constexpr __alt(in_place_t, _Args&&... __args)
7090b57cec5SDimitry Andric      : __value(_VSTD::forward<_Args>(__args)...) {}
7100b57cec5SDimitry Andric
7110b57cec5SDimitry Andric  __value_type __value;
7120b57cec5SDimitry Andric};
7130b57cec5SDimitry Andric
7140b57cec5SDimitry Andrictemplate <_Trait _DestructibleTrait, size_t _Index, class... _Types>
7150b57cec5SDimitry Andricunion _LIBCPP_TEMPLATE_VIS __union;
7160b57cec5SDimitry Andric
7170b57cec5SDimitry Andrictemplate <_Trait _DestructibleTrait, size_t _Index>
7180b57cec5SDimitry Andricunion _LIBCPP_TEMPLATE_VIS __union<_DestructibleTrait, _Index> {};
7190b57cec5SDimitry Andric
7200b57cec5SDimitry Andric#define _LIBCPP_VARIANT_UNION(destructible_trait, destructor)                  \
7210b57cec5SDimitry Andric  template <size_t _Index, class _Tp, class... _Types>                         \
7220b57cec5SDimitry Andric  union _LIBCPP_TEMPLATE_VIS __union<destructible_trait,                      \
7230b57cec5SDimitry Andric                                      _Index,                                  \
7240b57cec5SDimitry Andric                                      _Tp,                                     \
7250b57cec5SDimitry Andric                                      _Types...> {                             \
7260b57cec5SDimitry Andric  public:                                                                      \
7270b57cec5SDimitry Andric    inline _LIBCPP_INLINE_VISIBILITY                                           \
7280b57cec5SDimitry Andric    explicit constexpr __union(__valueless_t) noexcept : __dummy{} {}          \
7290b57cec5SDimitry Andric                                                                               \
7300b57cec5SDimitry Andric    template <class... _Args>                                                  \
7310b57cec5SDimitry Andric    inline _LIBCPP_INLINE_VISIBILITY                                           \
7320b57cec5SDimitry Andric    explicit constexpr __union(in_place_index_t<0>, _Args&&... __args)         \
7330b57cec5SDimitry Andric        : __head(in_place, _VSTD::forward<_Args>(__args)...) {}                \
7340b57cec5SDimitry Andric                                                                               \
7350b57cec5SDimitry Andric    template <size_t _Ip, class... _Args>                                      \
7360b57cec5SDimitry Andric    inline _LIBCPP_INLINE_VISIBILITY                                           \
7370b57cec5SDimitry Andric    explicit constexpr __union(in_place_index_t<_Ip>, _Args&&... __args)       \
7380b57cec5SDimitry Andric        : __tail(in_place_index<_Ip - 1>, _VSTD::forward<_Args>(__args)...) {} \
7390b57cec5SDimitry Andric                                                                               \
7400b57cec5SDimitry Andric    __union(const __union&) = default;                                         \
7410b57cec5SDimitry Andric    __union(__union&&) = default;                                              \
7420b57cec5SDimitry Andric                                                                               \
7430b57cec5SDimitry Andric    destructor                                                                 \
7440b57cec5SDimitry Andric                                                                               \
7450b57cec5SDimitry Andric    __union& operator=(const __union&) = default;                              \
7460b57cec5SDimitry Andric    __union& operator=(__union&&) = default;                                   \
7470b57cec5SDimitry Andric                                                                               \
7480b57cec5SDimitry Andric  private:                                                                     \
7490b57cec5SDimitry Andric    char __dummy;                                                              \
7500b57cec5SDimitry Andric    __alt<_Index, _Tp> __head;                                                 \
7510b57cec5SDimitry Andric    __union<destructible_trait, _Index + 1, _Types...> __tail;                 \
7520b57cec5SDimitry Andric                                                                               \
7530b57cec5SDimitry Andric    friend struct __access::__union;                                           \
7540b57cec5SDimitry Andric  }
7550b57cec5SDimitry Andric
7560b57cec5SDimitry Andric_LIBCPP_VARIANT_UNION(_Trait::_TriviallyAvailable, ~__union() = default;);
7570b57cec5SDimitry Andric_LIBCPP_VARIANT_UNION(_Trait::_Available, ~__union() {});
7580b57cec5SDimitry Andric_LIBCPP_VARIANT_UNION(_Trait::_Unavailable, ~__union() = delete;);
7590b57cec5SDimitry Andric
7600b57cec5SDimitry Andric#undef _LIBCPP_VARIANT_UNION
7610b57cec5SDimitry Andric
7620b57cec5SDimitry Andrictemplate <_Trait _DestructibleTrait, class... _Types>
7630b57cec5SDimitry Andricclass _LIBCPP_TEMPLATE_VIS __base {
7640b57cec5SDimitry Andricpublic:
7650b57cec5SDimitry Andric  using __index_t = __variant_index_t<sizeof...(_Types)>;
7660b57cec5SDimitry Andric
7670b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
7680b57cec5SDimitry Andric  explicit constexpr __base(__valueless_t tag) noexcept
7690b57cec5SDimitry Andric      : __data(tag), __index(__variant_npos<__index_t>) {}
7700b57cec5SDimitry Andric
7710b57cec5SDimitry Andric  template <size_t _Ip, class... _Args>
7720b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
7730b57cec5SDimitry Andric  explicit constexpr __base(in_place_index_t<_Ip>, _Args&&... __args)
7740b57cec5SDimitry Andric      :
7750b57cec5SDimitry Andric        __data(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...),
7760b57cec5SDimitry Andric        __index(_Ip) {}
7770b57cec5SDimitry Andric
7780b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
7790b57cec5SDimitry Andric  constexpr bool valueless_by_exception() const noexcept {
7800b57cec5SDimitry Andric    return index() == variant_npos;
7810b57cec5SDimitry Andric  }
7820b57cec5SDimitry Andric
7830b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
7840b57cec5SDimitry Andric  constexpr size_t index() const noexcept {
7850b57cec5SDimitry Andric    return __index == __variant_npos<__index_t> ? variant_npos : __index;
7860b57cec5SDimitry Andric  }
7870b57cec5SDimitry Andric
7880b57cec5SDimitry Andricprotected:
7890b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
7900b57cec5SDimitry Andric  constexpr auto&& __as_base() & { return *this; }
7910b57cec5SDimitry Andric
7920b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
7930b57cec5SDimitry Andric  constexpr auto&& __as_base() && { return _VSTD::move(*this); }
7940b57cec5SDimitry Andric
7950b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
7960b57cec5SDimitry Andric  constexpr auto&& __as_base() const & { return *this; }
7970b57cec5SDimitry Andric
7980b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
7990b57cec5SDimitry Andric  constexpr auto&& __as_base() const && { return _VSTD::move(*this); }
8000b57cec5SDimitry Andric
8010b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
8020b57cec5SDimitry Andric  static constexpr size_t __size() { return sizeof...(_Types); }
8030b57cec5SDimitry Andric
8040b57cec5SDimitry Andric  __union<_DestructibleTrait, 0, _Types...> __data;
8050b57cec5SDimitry Andric  __index_t __index;
8060b57cec5SDimitry Andric
8070b57cec5SDimitry Andric  friend struct __access::__base;
8080b57cec5SDimitry Andric  friend struct __visitation::__base;
8090b57cec5SDimitry Andric};
8100b57cec5SDimitry Andric
8110b57cec5SDimitry Andrictemplate <class _Traits, _Trait = _Traits::__destructible_trait>
812e8d8bef9SDimitry Andricclass _LIBCPP_TEMPLATE_VIS __dtor;
8130b57cec5SDimitry Andric
8140b57cec5SDimitry Andric#define _LIBCPP_VARIANT_DESTRUCTOR(destructible_trait, destructor, destroy)    \
8150b57cec5SDimitry Andric  template <class... _Types>                                                   \
816e8d8bef9SDimitry Andric  class _LIBCPP_TEMPLATE_VIS __dtor<__traits<_Types...>,                       \
8170b57cec5SDimitry Andric                                    destructible_trait>                        \
8180b57cec5SDimitry Andric      : public __base<destructible_trait, _Types...> {                         \
8190b57cec5SDimitry Andric    using __base_type = __base<destructible_trait, _Types...>;                 \
8200b57cec5SDimitry Andric    using __index_t = typename __base_type::__index_t;                         \
8210b57cec5SDimitry Andric                                                                               \
8220b57cec5SDimitry Andric  public:                                                                      \
8230b57cec5SDimitry Andric    using __base_type::__base_type;                                            \
8240b57cec5SDimitry Andric    using __base_type::operator=;                                              \
8250b57cec5SDimitry Andric                                                                               \
826e8d8bef9SDimitry Andric    __dtor(const __dtor&) = default;                                           \
827e8d8bef9SDimitry Andric    __dtor(__dtor&&) = default;                                                \
8280b57cec5SDimitry Andric    destructor                                                                 \
829e8d8bef9SDimitry Andric    __dtor& operator=(const __dtor&) = default;                                \
830e8d8bef9SDimitry Andric    __dtor& operator=(__dtor&&) = default;                                     \
8310b57cec5SDimitry Andric                                                                               \
8320b57cec5SDimitry Andric  protected:                                                                   \
8330b57cec5SDimitry Andric    inline _LIBCPP_INLINE_VISIBILITY                                           \
8340b57cec5SDimitry Andric    destroy                                                                    \
8350b57cec5SDimitry Andric  }
8360b57cec5SDimitry Andric
8370b57cec5SDimitry Andric_LIBCPP_VARIANT_DESTRUCTOR(
8380b57cec5SDimitry Andric    _Trait::_TriviallyAvailable,
839e8d8bef9SDimitry Andric    ~__dtor() = default;,
8400b57cec5SDimitry Andric    void __destroy() noexcept { this->__index = __variant_npos<__index_t>; });
8410b57cec5SDimitry Andric
8420b57cec5SDimitry Andric_LIBCPP_VARIANT_DESTRUCTOR(
8430b57cec5SDimitry Andric    _Trait::_Available,
844e8d8bef9SDimitry Andric    ~__dtor() { __destroy(); },
8450b57cec5SDimitry Andric    void __destroy() noexcept {
8460b57cec5SDimitry Andric      if (!this->valueless_by_exception()) {
8470b57cec5SDimitry Andric        __visitation::__base::__visit_alt(
8480b57cec5SDimitry Andric            [](auto& __alt) noexcept {
8490b57cec5SDimitry Andric              using __alt_type = __uncvref_t<decltype(__alt)>;
8500b57cec5SDimitry Andric              __alt.~__alt_type();
8510b57cec5SDimitry Andric            },
8520b57cec5SDimitry Andric            *this);
8530b57cec5SDimitry Andric      }
8540b57cec5SDimitry Andric      this->__index = __variant_npos<__index_t>;
8550b57cec5SDimitry Andric    });
8560b57cec5SDimitry Andric
8570b57cec5SDimitry Andric_LIBCPP_VARIANT_DESTRUCTOR(
8580b57cec5SDimitry Andric    _Trait::_Unavailable,
859e8d8bef9SDimitry Andric    ~__dtor() = delete;,
8600b57cec5SDimitry Andric    void __destroy() noexcept = delete;);
8610b57cec5SDimitry Andric
8620b57cec5SDimitry Andric#undef _LIBCPP_VARIANT_DESTRUCTOR
8630b57cec5SDimitry Andric
8640b57cec5SDimitry Andrictemplate <class _Traits>
865e8d8bef9SDimitry Andricclass _LIBCPP_TEMPLATE_VIS __ctor : public __dtor<_Traits> {
866e8d8bef9SDimitry Andric  using __base_type = __dtor<_Traits>;
8670b57cec5SDimitry Andric
8680b57cec5SDimitry Andricpublic:
8690b57cec5SDimitry Andric  using __base_type::__base_type;
8700b57cec5SDimitry Andric  using __base_type::operator=;
8710b57cec5SDimitry Andric
8720b57cec5SDimitry Andricprotected:
8730b57cec5SDimitry Andric  template <size_t _Ip, class _Tp, class... _Args>
8740b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
8750b57cec5SDimitry Andric  static _Tp& __construct_alt(__alt<_Ip, _Tp>& __a, _Args&&... __args) {
8760b57cec5SDimitry Andric    ::new ((void*)_VSTD::addressof(__a))
8770b57cec5SDimitry Andric        __alt<_Ip, _Tp>(in_place, _VSTD::forward<_Args>(__args)...);
8780b57cec5SDimitry Andric    return __a.__value;
8790b57cec5SDimitry Andric  }
8800b57cec5SDimitry Andric
8810b57cec5SDimitry Andric  template <class _Rhs>
8820b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
883e8d8bef9SDimitry Andric  static void __generic_construct(__ctor& __lhs, _Rhs&& __rhs) {
8840b57cec5SDimitry Andric    __lhs.__destroy();
8850b57cec5SDimitry Andric    if (!__rhs.valueless_by_exception()) {
8860b57cec5SDimitry Andric      __visitation::__base::__visit_alt_at(
8870b57cec5SDimitry Andric          __rhs.index(),
8880b57cec5SDimitry Andric          [](auto& __lhs_alt, auto&& __rhs_alt) {
8890b57cec5SDimitry Andric            __construct_alt(
8900b57cec5SDimitry Andric                __lhs_alt,
8910b57cec5SDimitry Andric                _VSTD::forward<decltype(__rhs_alt)>(__rhs_alt).__value);
8920b57cec5SDimitry Andric          },
8930b57cec5SDimitry Andric          __lhs, _VSTD::forward<_Rhs>(__rhs));
8940b57cec5SDimitry Andric      __lhs.__index = __rhs.index();
8950b57cec5SDimitry Andric    }
8960b57cec5SDimitry Andric  }
8970b57cec5SDimitry Andric};
8980b57cec5SDimitry Andric
8990b57cec5SDimitry Andrictemplate <class _Traits, _Trait = _Traits::__move_constructible_trait>
9000b57cec5SDimitry Andricclass _LIBCPP_TEMPLATE_VIS __move_constructor;
9010b57cec5SDimitry Andric
9020b57cec5SDimitry Andric#define _LIBCPP_VARIANT_MOVE_CONSTRUCTOR(move_constructible_trait,             \
9030b57cec5SDimitry Andric                                         move_constructor)                     \
9040b57cec5SDimitry Andric  template <class... _Types>                                                   \
9050b57cec5SDimitry Andric  class _LIBCPP_TEMPLATE_VIS __move_constructor<__traits<_Types...>,           \
9060b57cec5SDimitry Andric                                                move_constructible_trait>      \
907e8d8bef9SDimitry Andric      : public __ctor<__traits<_Types...>> {                                   \
908e8d8bef9SDimitry Andric    using __base_type = __ctor<__traits<_Types...>>;                           \
9090b57cec5SDimitry Andric                                                                               \
9100b57cec5SDimitry Andric  public:                                                                      \
9110b57cec5SDimitry Andric    using __base_type::__base_type;                                            \
9120b57cec5SDimitry Andric    using __base_type::operator=;                                              \
9130b57cec5SDimitry Andric                                                                               \
9140b57cec5SDimitry Andric    __move_constructor(const __move_constructor&) = default;                   \
9150b57cec5SDimitry Andric    move_constructor                                                           \
9160b57cec5SDimitry Andric    ~__move_constructor() = default;                                           \
9170b57cec5SDimitry Andric    __move_constructor& operator=(const __move_constructor&) = default;        \
9180b57cec5SDimitry Andric    __move_constructor& operator=(__move_constructor&&) = default;             \
9190b57cec5SDimitry Andric  }
9200b57cec5SDimitry Andric
9210b57cec5SDimitry Andric_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
9220b57cec5SDimitry Andric    _Trait::_TriviallyAvailable,
9230b57cec5SDimitry Andric    __move_constructor(__move_constructor&& __that) = default;);
9240b57cec5SDimitry Andric
9250b57cec5SDimitry Andric_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
9260b57cec5SDimitry Andric    _Trait::_Available,
9270b57cec5SDimitry Andric    __move_constructor(__move_constructor&& __that) noexcept(
9280b57cec5SDimitry Andric        __all<is_nothrow_move_constructible_v<_Types>...>::value)
9290b57cec5SDimitry Andric        : __move_constructor(__valueless_t{}) {
9300b57cec5SDimitry Andric      this->__generic_construct(*this, _VSTD::move(__that));
9310b57cec5SDimitry Andric    });
9320b57cec5SDimitry Andric
9330b57cec5SDimitry Andric_LIBCPP_VARIANT_MOVE_CONSTRUCTOR(
9340b57cec5SDimitry Andric    _Trait::_Unavailable,
9350b57cec5SDimitry Andric    __move_constructor(__move_constructor&&) = delete;);
9360b57cec5SDimitry Andric
9370b57cec5SDimitry Andric#undef _LIBCPP_VARIANT_MOVE_CONSTRUCTOR
9380b57cec5SDimitry Andric
9390b57cec5SDimitry Andrictemplate <class _Traits, _Trait = _Traits::__copy_constructible_trait>
9400b57cec5SDimitry Andricclass _LIBCPP_TEMPLATE_VIS __copy_constructor;
9410b57cec5SDimitry Andric
9420b57cec5SDimitry Andric#define _LIBCPP_VARIANT_COPY_CONSTRUCTOR(copy_constructible_trait,             \
9430b57cec5SDimitry Andric                                         copy_constructor)                     \
9440b57cec5SDimitry Andric  template <class... _Types>                                                   \
9450b57cec5SDimitry Andric  class _LIBCPP_TEMPLATE_VIS __copy_constructor<__traits<_Types...>,          \
9460b57cec5SDimitry Andric                                                 copy_constructible_trait>     \
9470b57cec5SDimitry Andric      : public __move_constructor<__traits<_Types...>> {                       \
9480b57cec5SDimitry Andric    using __base_type = __move_constructor<__traits<_Types...>>;               \
9490b57cec5SDimitry Andric                                                                               \
9500b57cec5SDimitry Andric  public:                                                                      \
9510b57cec5SDimitry Andric    using __base_type::__base_type;                                            \
9520b57cec5SDimitry Andric    using __base_type::operator=;                                              \
9530b57cec5SDimitry Andric                                                                               \
9540b57cec5SDimitry Andric    copy_constructor                                                           \
9550b57cec5SDimitry Andric    __copy_constructor(__copy_constructor&&) = default;                        \
9560b57cec5SDimitry Andric    ~__copy_constructor() = default;                                           \
9570b57cec5SDimitry Andric    __copy_constructor& operator=(const __copy_constructor&) = default;        \
9580b57cec5SDimitry Andric    __copy_constructor& operator=(__copy_constructor&&) = default;             \
9590b57cec5SDimitry Andric  }
9600b57cec5SDimitry Andric
9610b57cec5SDimitry Andric_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
9620b57cec5SDimitry Andric    _Trait::_TriviallyAvailable,
9630b57cec5SDimitry Andric    __copy_constructor(const __copy_constructor& __that) = default;);
9640b57cec5SDimitry Andric
9650b57cec5SDimitry Andric_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
9660b57cec5SDimitry Andric    _Trait::_Available,
9670b57cec5SDimitry Andric    __copy_constructor(const __copy_constructor& __that)
9680b57cec5SDimitry Andric        : __copy_constructor(__valueless_t{}) {
9690b57cec5SDimitry Andric      this->__generic_construct(*this, __that);
9700b57cec5SDimitry Andric    });
9710b57cec5SDimitry Andric
9720b57cec5SDimitry Andric_LIBCPP_VARIANT_COPY_CONSTRUCTOR(
9730b57cec5SDimitry Andric    _Trait::_Unavailable,
9740b57cec5SDimitry Andric    __copy_constructor(const __copy_constructor&) = delete;);
9750b57cec5SDimitry Andric
9760b57cec5SDimitry Andric#undef _LIBCPP_VARIANT_COPY_CONSTRUCTOR
9770b57cec5SDimitry Andric
9780b57cec5SDimitry Andrictemplate <class _Traits>
9790b57cec5SDimitry Andricclass _LIBCPP_TEMPLATE_VIS __assignment : public __copy_constructor<_Traits> {
9800b57cec5SDimitry Andric  using __base_type = __copy_constructor<_Traits>;
9810b57cec5SDimitry Andric
9820b57cec5SDimitry Andricpublic:
9830b57cec5SDimitry Andric  using __base_type::__base_type;
9840b57cec5SDimitry Andric  using __base_type::operator=;
9850b57cec5SDimitry Andric
9860b57cec5SDimitry Andric  template <size_t _Ip, class... _Args>
9870b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
9880b57cec5SDimitry Andric  auto& __emplace(_Args&&... __args) {
9890b57cec5SDimitry Andric    this->__destroy();
9900b57cec5SDimitry Andric    auto& __res = this->__construct_alt(__access::__base::__get_alt<_Ip>(*this),
9910b57cec5SDimitry Andric                          _VSTD::forward<_Args>(__args)...);
9920b57cec5SDimitry Andric    this->__index = _Ip;
9930b57cec5SDimitry Andric    return __res;
9940b57cec5SDimitry Andric  }
9950b57cec5SDimitry Andric
9960b57cec5SDimitry Andricprotected:
9970b57cec5SDimitry Andric  template <size_t _Ip, class _Tp, class _Arg>
9980b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
9990b57cec5SDimitry Andric  void __assign_alt(__alt<_Ip, _Tp>& __a, _Arg&& __arg) {
10000b57cec5SDimitry Andric    if (this->index() == _Ip) {
10010b57cec5SDimitry Andric      __a.__value = _VSTD::forward<_Arg>(__arg);
10020b57cec5SDimitry Andric    } else {
10030b57cec5SDimitry Andric      struct {
10040b57cec5SDimitry Andric        void operator()(true_type) const {
10050b57cec5SDimitry Andric          __this->__emplace<_Ip>(_VSTD::forward<_Arg>(__arg));
10060b57cec5SDimitry Andric        }
10070b57cec5SDimitry Andric        void operator()(false_type) const {
10080b57cec5SDimitry Andric          __this->__emplace<_Ip>(_Tp(_VSTD::forward<_Arg>(__arg)));
10090b57cec5SDimitry Andric        }
10100b57cec5SDimitry Andric        __assignment* __this;
10110b57cec5SDimitry Andric        _Arg&& __arg;
10120b57cec5SDimitry Andric      } __impl{this, _VSTD::forward<_Arg>(__arg)};
10130b57cec5SDimitry Andric      __impl(bool_constant<is_nothrow_constructible_v<_Tp, _Arg> ||
10140b57cec5SDimitry Andric                           !is_nothrow_move_constructible_v<_Tp>>{});
10150b57cec5SDimitry Andric    }
10160b57cec5SDimitry Andric  }
10170b57cec5SDimitry Andric
10180b57cec5SDimitry Andric  template <class _That>
10190b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
10200b57cec5SDimitry Andric  void __generic_assign(_That&& __that) {
10210b57cec5SDimitry Andric    if (this->valueless_by_exception() && __that.valueless_by_exception()) {
10220b57cec5SDimitry Andric      // do nothing.
10230b57cec5SDimitry Andric    } else if (__that.valueless_by_exception()) {
10240b57cec5SDimitry Andric      this->__destroy();
10250b57cec5SDimitry Andric    } else {
10260b57cec5SDimitry Andric      __visitation::__base::__visit_alt_at(
10270b57cec5SDimitry Andric          __that.index(),
10280b57cec5SDimitry Andric          [this](auto& __this_alt, auto&& __that_alt) {
10290b57cec5SDimitry Andric            this->__assign_alt(
10300b57cec5SDimitry Andric                __this_alt,
10310b57cec5SDimitry Andric                _VSTD::forward<decltype(__that_alt)>(__that_alt).__value);
10320b57cec5SDimitry Andric          },
10330b57cec5SDimitry Andric          *this, _VSTD::forward<_That>(__that));
10340b57cec5SDimitry Andric    }
10350b57cec5SDimitry Andric  }
10360b57cec5SDimitry Andric};
10370b57cec5SDimitry Andric
10380b57cec5SDimitry Andrictemplate <class _Traits, _Trait = _Traits::__move_assignable_trait>
10390b57cec5SDimitry Andricclass _LIBCPP_TEMPLATE_VIS __move_assignment;
10400b57cec5SDimitry Andric
10410b57cec5SDimitry Andric#define _LIBCPP_VARIANT_MOVE_ASSIGNMENT(move_assignable_trait,                 \
10420b57cec5SDimitry Andric                                        move_assignment)                       \
10430b57cec5SDimitry Andric  template <class... _Types>                                                   \
10440b57cec5SDimitry Andric  class _LIBCPP_TEMPLATE_VIS __move_assignment<__traits<_Types...>,           \
10450b57cec5SDimitry Andric                                                move_assignable_trait>         \
10460b57cec5SDimitry Andric      : public __assignment<__traits<_Types...>> {                             \
10470b57cec5SDimitry Andric    using __base_type = __assignment<__traits<_Types...>>;                     \
10480b57cec5SDimitry Andric                                                                               \
10490b57cec5SDimitry Andric  public:                                                                      \
10500b57cec5SDimitry Andric    using __base_type::__base_type;                                            \
10510b57cec5SDimitry Andric    using __base_type::operator=;                                              \
10520b57cec5SDimitry Andric                                                                               \
10530b57cec5SDimitry Andric    __move_assignment(const __move_assignment&) = default;                     \
10540b57cec5SDimitry Andric    __move_assignment(__move_assignment&&) = default;                          \
10550b57cec5SDimitry Andric    ~__move_assignment() = default;                                            \
10560b57cec5SDimitry Andric    __move_assignment& operator=(const __move_assignment&) = default;          \
10570b57cec5SDimitry Andric    move_assignment                                                            \
10580b57cec5SDimitry Andric  }
10590b57cec5SDimitry Andric
10600b57cec5SDimitry Andric_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
10610b57cec5SDimitry Andric    _Trait::_TriviallyAvailable,
10620b57cec5SDimitry Andric    __move_assignment& operator=(__move_assignment&& __that) = default;);
10630b57cec5SDimitry Andric
10640b57cec5SDimitry Andric_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
10650b57cec5SDimitry Andric    _Trait::_Available,
10660b57cec5SDimitry Andric    __move_assignment& operator=(__move_assignment&& __that) noexcept(
10670b57cec5SDimitry Andric        __all<(is_nothrow_move_constructible_v<_Types> &&
10680b57cec5SDimitry Andric               is_nothrow_move_assignable_v<_Types>)...>::value) {
10690b57cec5SDimitry Andric      this->__generic_assign(_VSTD::move(__that));
10700b57cec5SDimitry Andric      return *this;
10710b57cec5SDimitry Andric    });
10720b57cec5SDimitry Andric
10730b57cec5SDimitry Andric_LIBCPP_VARIANT_MOVE_ASSIGNMENT(
10740b57cec5SDimitry Andric    _Trait::_Unavailable,
10750b57cec5SDimitry Andric    __move_assignment& operator=(__move_assignment&&) = delete;);
10760b57cec5SDimitry Andric
10770b57cec5SDimitry Andric#undef _LIBCPP_VARIANT_MOVE_ASSIGNMENT
10780b57cec5SDimitry Andric
10790b57cec5SDimitry Andrictemplate <class _Traits, _Trait = _Traits::__copy_assignable_trait>
10800b57cec5SDimitry Andricclass _LIBCPP_TEMPLATE_VIS __copy_assignment;
10810b57cec5SDimitry Andric
10820b57cec5SDimitry Andric#define _LIBCPP_VARIANT_COPY_ASSIGNMENT(copy_assignable_trait,                 \
10830b57cec5SDimitry Andric                                        copy_assignment)                       \
10840b57cec5SDimitry Andric  template <class... _Types>                                                   \
10850b57cec5SDimitry Andric  class _LIBCPP_TEMPLATE_VIS __copy_assignment<__traits<_Types...>,           \
10860b57cec5SDimitry Andric                                                copy_assignable_trait>         \
10870b57cec5SDimitry Andric      : public __move_assignment<__traits<_Types...>> {                        \
10880b57cec5SDimitry Andric    using __base_type = __move_assignment<__traits<_Types...>>;                \
10890b57cec5SDimitry Andric                                                                               \
10900b57cec5SDimitry Andric  public:                                                                      \
10910b57cec5SDimitry Andric    using __base_type::__base_type;                                            \
10920b57cec5SDimitry Andric    using __base_type::operator=;                                              \
10930b57cec5SDimitry Andric                                                                               \
10940b57cec5SDimitry Andric    __copy_assignment(const __copy_assignment&) = default;                     \
10950b57cec5SDimitry Andric    __copy_assignment(__copy_assignment&&) = default;                          \
10960b57cec5SDimitry Andric    ~__copy_assignment() = default;                                            \
10970b57cec5SDimitry Andric    copy_assignment                                                            \
10980b57cec5SDimitry Andric    __copy_assignment& operator=(__copy_assignment&&) = default;               \
10990b57cec5SDimitry Andric  }
11000b57cec5SDimitry Andric
11010b57cec5SDimitry Andric_LIBCPP_VARIANT_COPY_ASSIGNMENT(
11020b57cec5SDimitry Andric    _Trait::_TriviallyAvailable,
11030b57cec5SDimitry Andric    __copy_assignment& operator=(const __copy_assignment& __that) = default;);
11040b57cec5SDimitry Andric
11050b57cec5SDimitry Andric_LIBCPP_VARIANT_COPY_ASSIGNMENT(
11060b57cec5SDimitry Andric    _Trait::_Available,
11070b57cec5SDimitry Andric    __copy_assignment& operator=(const __copy_assignment& __that) {
11080b57cec5SDimitry Andric      this->__generic_assign(__that);
11090b57cec5SDimitry Andric      return *this;
11100b57cec5SDimitry Andric    });
11110b57cec5SDimitry Andric
11120b57cec5SDimitry Andric_LIBCPP_VARIANT_COPY_ASSIGNMENT(
11130b57cec5SDimitry Andric    _Trait::_Unavailable,
11140b57cec5SDimitry Andric    __copy_assignment& operator=(const __copy_assignment&) = delete;);
11150b57cec5SDimitry Andric
11160b57cec5SDimitry Andric#undef _LIBCPP_VARIANT_COPY_ASSIGNMENT
11170b57cec5SDimitry Andric
11180b57cec5SDimitry Andrictemplate <class... _Types>
11190b57cec5SDimitry Andricclass _LIBCPP_TEMPLATE_VIS __impl
11200b57cec5SDimitry Andric    : public __copy_assignment<__traits<_Types...>> {
11210b57cec5SDimitry Andric  using __base_type = __copy_assignment<__traits<_Types...>>;
11220b57cec5SDimitry Andric
11230b57cec5SDimitry Andricpublic:
11240b57cec5SDimitry Andric  using __base_type::__base_type;
11250b57cec5SDimitry Andric  using __base_type::operator=;
11260b57cec5SDimitry Andric
11270b57cec5SDimitry Andric  template <size_t _Ip, class _Arg>
11280b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
11290b57cec5SDimitry Andric  void __assign(_Arg&& __arg) {
11300b57cec5SDimitry Andric    this->__assign_alt(__access::__base::__get_alt<_Ip>(*this),
11310b57cec5SDimitry Andric                       _VSTD::forward<_Arg>(__arg));
11320b57cec5SDimitry Andric  }
11330b57cec5SDimitry Andric
11340b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
11350b57cec5SDimitry Andric  void __swap(__impl& __that)  {
11360b57cec5SDimitry Andric    if (this->valueless_by_exception() && __that.valueless_by_exception()) {
11370b57cec5SDimitry Andric      // do nothing.
11380b57cec5SDimitry Andric    } else if (this->index() == __that.index()) {
11390b57cec5SDimitry Andric      __visitation::__base::__visit_alt_at(
11400b57cec5SDimitry Andric          this->index(),
11410b57cec5SDimitry Andric          [](auto& __this_alt, auto& __that_alt) {
11420b57cec5SDimitry Andric            using _VSTD::swap;
11430b57cec5SDimitry Andric            swap(__this_alt.__value, __that_alt.__value);
11440b57cec5SDimitry Andric          },
11450b57cec5SDimitry Andric          *this,
11460b57cec5SDimitry Andric          __that);
11470b57cec5SDimitry Andric    } else {
11480b57cec5SDimitry Andric      __impl* __lhs = this;
11490b57cec5SDimitry Andric      __impl* __rhs = _VSTD::addressof(__that);
11500b57cec5SDimitry Andric      if (__lhs->__move_nothrow() && !__rhs->__move_nothrow()) {
11510b57cec5SDimitry Andric        _VSTD::swap(__lhs, __rhs);
11520b57cec5SDimitry Andric      }
11530b57cec5SDimitry Andric      __impl __tmp(_VSTD::move(*__rhs));
11540b57cec5SDimitry Andric#ifndef _LIBCPP_NO_EXCEPTIONS
11555ffd83dbSDimitry Andric      if constexpr (__all<is_nothrow_move_constructible_v<_Types>...>::value) {
11565ffd83dbSDimitry Andric        this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
11575ffd83dbSDimitry Andric      } else {
11580b57cec5SDimitry Andric        // EXTENSION: When the move construction of `__lhs` into `__rhs` throws
11590b57cec5SDimitry Andric        // and `__tmp` is nothrow move constructible then we move `__tmp` back
11600b57cec5SDimitry Andric        // into `__rhs` and provide the strong exception safety guarantee.
11610b57cec5SDimitry Andric        try {
11620b57cec5SDimitry Andric          this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
11630b57cec5SDimitry Andric        } catch (...) {
11640b57cec5SDimitry Andric          if (__tmp.__move_nothrow()) {
11650b57cec5SDimitry Andric            this->__generic_construct(*__rhs, _VSTD::move(__tmp));
11660b57cec5SDimitry Andric          }
11670b57cec5SDimitry Andric          throw;
11680b57cec5SDimitry Andric        }
11695ffd83dbSDimitry Andric      }
11700b57cec5SDimitry Andric#else
11715ffd83dbSDimitry Andric      // this isn't consolidated with the `if constexpr` branch above due to
11725ffd83dbSDimitry Andric      // `throw` being ill-formed with exceptions disabled even when discarded.
11730b57cec5SDimitry Andric      this->__generic_construct(*__rhs, _VSTD::move(*__lhs));
11740b57cec5SDimitry Andric#endif
11750b57cec5SDimitry Andric      this->__generic_construct(*__lhs, _VSTD::move(__tmp));
11760b57cec5SDimitry Andric    }
11770b57cec5SDimitry Andric  }
11780b57cec5SDimitry Andric
11790b57cec5SDimitry Andricprivate:
11800b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
11810b57cec5SDimitry Andric  bool __move_nothrow() const {
11820b57cec5SDimitry Andric    constexpr bool __results[] = {is_nothrow_move_constructible_v<_Types>...};
11830b57cec5SDimitry Andric    return this->valueless_by_exception() || __results[this->index()];
11840b57cec5SDimitry Andric  }
11850b57cec5SDimitry Andric};
11860b57cec5SDimitry Andric
11870b57cec5SDimitry Andricstruct __no_narrowing_check {
11880b57cec5SDimitry Andric  template <class _Dest, class _Source>
11890b57cec5SDimitry Andric  using _Apply = __identity<_Dest>;
11900b57cec5SDimitry Andric};
11910b57cec5SDimitry Andric
11920b57cec5SDimitry Andricstruct __narrowing_check {
11930b57cec5SDimitry Andric  template <class _Dest>
11940b57cec5SDimitry Andric  static auto __test_impl(_Dest (&&)[1]) -> __identity<_Dest>;
11950b57cec5SDimitry Andric  template <class _Dest, class _Source>
1196*349cc55cSDimitry Andric  using _Apply _LIBCPP_NODEBUG = decltype(__test_impl<_Dest>({declval<_Source>()}));
11970b57cec5SDimitry Andric};
11980b57cec5SDimitry Andric
11990b57cec5SDimitry Andrictemplate <class _Dest, class _Source>
1200*349cc55cSDimitry Andricusing __check_for_narrowing _LIBCPP_NODEBUG =
12010b57cec5SDimitry Andric  typename _If<
12020b57cec5SDimitry Andric#ifdef _LIBCPP_ENABLE_NARROWING_CONVERSIONS_IN_VARIANT
12030b57cec5SDimitry Andric    false &&
12040b57cec5SDimitry Andric#endif
12050b57cec5SDimitry Andric    is_arithmetic<_Dest>::value,
12060b57cec5SDimitry Andric    __narrowing_check,
12070b57cec5SDimitry Andric    __no_narrowing_check
12080b57cec5SDimitry Andric  >::template _Apply<_Dest, _Source>;
12090b57cec5SDimitry Andric
12100b57cec5SDimitry Andrictemplate <class _Tp, size_t _Idx>
12110b57cec5SDimitry Andricstruct __overload {
12120b57cec5SDimitry Andric  template <class _Up>
12130b57cec5SDimitry Andric  auto operator()(_Tp, _Up&&) const -> __check_for_narrowing<_Tp, _Up>;
12140b57cec5SDimitry Andric};
12150b57cec5SDimitry Andric
12160b57cec5SDimitry Andrictemplate <class _Tp, size_t>
12170b57cec5SDimitry Andricstruct __overload_bool  {
12180b57cec5SDimitry Andric  template <class _Up, class _Ap = __uncvref_t<_Up>>
12190b57cec5SDimitry Andric  auto operator()(bool, _Up&&) const
12200b57cec5SDimitry Andric      -> enable_if_t<is_same_v<_Ap, bool>, __identity<_Tp>>;
12210b57cec5SDimitry Andric};
12220b57cec5SDimitry Andric
12230b57cec5SDimitry Andrictemplate <size_t _Idx>
12240b57cec5SDimitry Andricstruct __overload<bool, _Idx> : __overload_bool<bool, _Idx> {};
12250b57cec5SDimitry Andrictemplate <size_t _Idx>
12260b57cec5SDimitry Andricstruct __overload<bool const, _Idx> : __overload_bool<bool const, _Idx> {};
12270b57cec5SDimitry Andrictemplate <size_t _Idx>
12280b57cec5SDimitry Andricstruct __overload<bool volatile, _Idx> : __overload_bool<bool volatile, _Idx> {};
12290b57cec5SDimitry Andrictemplate <size_t _Idx>
12300b57cec5SDimitry Andricstruct __overload<bool const volatile, _Idx> : __overload_bool<bool const volatile, _Idx> {};
12310b57cec5SDimitry Andric
12320b57cec5SDimitry Andrictemplate <class ..._Bases>
12330b57cec5SDimitry Andricstruct __all_overloads : _Bases... {
12340b57cec5SDimitry Andric  void operator()() const;
12350b57cec5SDimitry Andric  using _Bases::operator()...;
12360b57cec5SDimitry Andric};
12370b57cec5SDimitry Andric
12380b57cec5SDimitry Andrictemplate <class IdxSeq>
12390b57cec5SDimitry Andricstruct __make_overloads_imp;
12400b57cec5SDimitry Andric
12410b57cec5SDimitry Andrictemplate <size_t ..._Idx>
12420b57cec5SDimitry Andricstruct __make_overloads_imp<__tuple_indices<_Idx...> > {
12430b57cec5SDimitry Andric  template <class ..._Types>
1244*349cc55cSDimitry Andric  using _Apply _LIBCPP_NODEBUG = __all_overloads<__overload<_Types, _Idx>...>;
12450b57cec5SDimitry Andric};
12460b57cec5SDimitry Andric
12470b57cec5SDimitry Andrictemplate <class ..._Types>
1248*349cc55cSDimitry Andricusing _MakeOverloads _LIBCPP_NODEBUG = typename __make_overloads_imp<
12490b57cec5SDimitry Andric    __make_indices_imp<sizeof...(_Types), 0> >::template _Apply<_Types...>;
12500b57cec5SDimitry Andric
12510b57cec5SDimitry Andrictemplate <class _Tp, class... _Types>
12520b57cec5SDimitry Andricusing __best_match_t =
12530b57cec5SDimitry Andric    typename invoke_result_t<_MakeOverloads<_Types...>, _Tp, _Tp>::type;
12540b57cec5SDimitry Andric
12550b57cec5SDimitry Andric} // __variant_detail
12560b57cec5SDimitry Andric
12570b57cec5SDimitry Andrictemplate <class... _Types>
12580b57cec5SDimitry Andricclass _LIBCPP_TEMPLATE_VIS variant
12590b57cec5SDimitry Andric    : private __sfinae_ctor_base<
12600b57cec5SDimitry Andric          __all<is_copy_constructible_v<_Types>...>::value,
12610b57cec5SDimitry Andric          __all<is_move_constructible_v<_Types>...>::value>,
12620b57cec5SDimitry Andric      private __sfinae_assign_base<
12630b57cec5SDimitry Andric          __all<(is_copy_constructible_v<_Types> &&
12640b57cec5SDimitry Andric                 is_copy_assignable_v<_Types>)...>::value,
12650b57cec5SDimitry Andric          __all<(is_move_constructible_v<_Types> &&
12660b57cec5SDimitry Andric                 is_move_assignable_v<_Types>)...>::value> {
12670b57cec5SDimitry Andric  static_assert(0 < sizeof...(_Types),
12680b57cec5SDimitry Andric                "variant must consist of at least one alternative.");
12690b57cec5SDimitry Andric
12700b57cec5SDimitry Andric  static_assert(__all<!is_array_v<_Types>...>::value,
12710b57cec5SDimitry Andric                "variant can not have an array type as an alternative.");
12720b57cec5SDimitry Andric
12730b57cec5SDimitry Andric  static_assert(__all<!is_reference_v<_Types>...>::value,
12740b57cec5SDimitry Andric                "variant can not have a reference type as an alternative.");
12750b57cec5SDimitry Andric
12760b57cec5SDimitry Andric  static_assert(__all<!is_void_v<_Types>...>::value,
12770b57cec5SDimitry Andric                "variant can not have a void type as an alternative.");
12780b57cec5SDimitry Andric
12790b57cec5SDimitry Andric  using __first_type = variant_alternative_t<0, variant>;
12800b57cec5SDimitry Andric
12810b57cec5SDimitry Andricpublic:
12820b57cec5SDimitry Andric  template <bool _Dummy = true,
12830b57cec5SDimitry Andric            enable_if_t<__dependent_type<is_default_constructible<__first_type>,
12840b57cec5SDimitry Andric                                         _Dummy>::value,
12850b57cec5SDimitry Andric                        int> = 0>
12860b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
12870b57cec5SDimitry Andric  constexpr variant() noexcept(is_nothrow_default_constructible_v<__first_type>)
12880b57cec5SDimitry Andric      : __impl(in_place_index<0>) {}
12890b57cec5SDimitry Andric
12900b57cec5SDimitry Andric  variant(const variant&) = default;
12910b57cec5SDimitry Andric  variant(variant&&) = default;
12920b57cec5SDimitry Andric
12930b57cec5SDimitry Andric  template <
12940b57cec5SDimitry Andric      class _Arg,
12950b57cec5SDimitry Andric      enable_if_t<!is_same_v<__uncvref_t<_Arg>, variant>, int> = 0,
12960b57cec5SDimitry Andric      enable_if_t<!__is_inplace_type<__uncvref_t<_Arg>>::value, int> = 0,
12970b57cec5SDimitry Andric      enable_if_t<!__is_inplace_index<__uncvref_t<_Arg>>::value, int> = 0,
12980b57cec5SDimitry Andric      class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
12990b57cec5SDimitry Andric      size_t _Ip =
13000b57cec5SDimitry Andric          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
13010b57cec5SDimitry Andric      enable_if_t<is_constructible_v<_Tp, _Arg>, int> = 0>
13020b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
13030b57cec5SDimitry Andric  constexpr variant(_Arg&& __arg) noexcept(
13040b57cec5SDimitry Andric      is_nothrow_constructible_v<_Tp, _Arg>)
13050b57cec5SDimitry Andric      : __impl(in_place_index<_Ip>, _VSTD::forward<_Arg>(__arg)) {}
13060b57cec5SDimitry Andric
13070b57cec5SDimitry Andric  template <size_t _Ip, class... _Args,
13080b57cec5SDimitry Andric            class = enable_if_t<(_Ip < sizeof...(_Types)), int>,
13090b57cec5SDimitry Andric            class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
13100b57cec5SDimitry Andric            enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
13110b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
13120b57cec5SDimitry Andric  explicit constexpr variant(
13130b57cec5SDimitry Andric      in_place_index_t<_Ip>,
13140b57cec5SDimitry Andric      _Args&&... __args) noexcept(is_nothrow_constructible_v<_Tp, _Args...>)
13150b57cec5SDimitry Andric      : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {}
13160b57cec5SDimitry Andric
13170b57cec5SDimitry Andric  template <
13180b57cec5SDimitry Andric      size_t _Ip,
13190b57cec5SDimitry Andric      class _Up,
13200b57cec5SDimitry Andric      class... _Args,
13210b57cec5SDimitry Andric      enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
13220b57cec5SDimitry Andric      class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
13230b57cec5SDimitry Andric      enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
13240b57cec5SDimitry Andric                  int> = 0>
13250b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
13260b57cec5SDimitry Andric  explicit constexpr variant(
13270b57cec5SDimitry Andric      in_place_index_t<_Ip>,
13280b57cec5SDimitry Andric      initializer_list<_Up> __il,
13290b57cec5SDimitry Andric      _Args&&... __args) noexcept(
13300b57cec5SDimitry Andric      is_nothrow_constructible_v<_Tp, initializer_list<_Up>&, _Args...>)
13310b57cec5SDimitry Andric      : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {}
13320b57cec5SDimitry Andric
13330b57cec5SDimitry Andric  template <
13340b57cec5SDimitry Andric      class _Tp,
13350b57cec5SDimitry Andric      class... _Args,
13360b57cec5SDimitry Andric      size_t _Ip =
13370b57cec5SDimitry Andric          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
13380b57cec5SDimitry Andric      enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
13390b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
13400b57cec5SDimitry Andric  explicit constexpr variant(in_place_type_t<_Tp>, _Args&&... __args) noexcept(
13410b57cec5SDimitry Andric      is_nothrow_constructible_v<_Tp, _Args...>)
13420b57cec5SDimitry Andric      : __impl(in_place_index<_Ip>, _VSTD::forward<_Args>(__args)...) {}
13430b57cec5SDimitry Andric
13440b57cec5SDimitry Andric  template <
13450b57cec5SDimitry Andric      class _Tp,
13460b57cec5SDimitry Andric      class _Up,
13470b57cec5SDimitry Andric      class... _Args,
13480b57cec5SDimitry Andric      size_t _Ip =
13490b57cec5SDimitry Andric          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
13500b57cec5SDimitry Andric      enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
13510b57cec5SDimitry Andric                  int> = 0>
13520b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
13530b57cec5SDimitry Andric  explicit constexpr variant(
13540b57cec5SDimitry Andric      in_place_type_t<_Tp>,
13550b57cec5SDimitry Andric      initializer_list<_Up> __il,
13560b57cec5SDimitry Andric      _Args&&... __args) noexcept(
13570b57cec5SDimitry Andric      is_nothrow_constructible_v<_Tp, initializer_list< _Up>&, _Args...>)
13580b57cec5SDimitry Andric      : __impl(in_place_index<_Ip>, __il, _VSTD::forward<_Args>(__args)...) {}
13590b57cec5SDimitry Andric
13600b57cec5SDimitry Andric  ~variant() = default;
13610b57cec5SDimitry Andric
13620b57cec5SDimitry Andric  variant& operator=(const variant&) = default;
13630b57cec5SDimitry Andric  variant& operator=(variant&&) = default;
13640b57cec5SDimitry Andric
13650b57cec5SDimitry Andric  template <
13660b57cec5SDimitry Andric      class _Arg,
13670b57cec5SDimitry Andric      enable_if_t<!is_same_v<__uncvref_t<_Arg>, variant>, int> = 0,
13680b57cec5SDimitry Andric      class _Tp = __variant_detail::__best_match_t<_Arg, _Types...>,
13690b57cec5SDimitry Andric      size_t _Ip =
13700b57cec5SDimitry Andric          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
13710b57cec5SDimitry Andric      enable_if_t<is_assignable_v<_Tp&, _Arg> && is_constructible_v<_Tp, _Arg>,
13720b57cec5SDimitry Andric                  int> = 0>
13730b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
13740b57cec5SDimitry Andric  variant& operator=(_Arg&& __arg) noexcept(
13750b57cec5SDimitry Andric      is_nothrow_assignable_v<_Tp&, _Arg> &&
13760b57cec5SDimitry Andric      is_nothrow_constructible_v<_Tp, _Arg>) {
13770b57cec5SDimitry Andric    __impl.template __assign<_Ip>(_VSTD::forward<_Arg>(__arg));
13780b57cec5SDimitry Andric    return *this;
13790b57cec5SDimitry Andric  }
13800b57cec5SDimitry Andric
13810b57cec5SDimitry Andric  template <
13820b57cec5SDimitry Andric      size_t _Ip,
13830b57cec5SDimitry Andric      class... _Args,
13840b57cec5SDimitry Andric      enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
13850b57cec5SDimitry Andric      class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
13860b57cec5SDimitry Andric      enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
13870b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
13880b57cec5SDimitry Andric  _Tp& emplace(_Args&&... __args) {
13890b57cec5SDimitry Andric    return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...);
13900b57cec5SDimitry Andric  }
13910b57cec5SDimitry Andric
13920b57cec5SDimitry Andric  template <
13930b57cec5SDimitry Andric      size_t _Ip,
13940b57cec5SDimitry Andric      class _Up,
13950b57cec5SDimitry Andric      class... _Args,
13960b57cec5SDimitry Andric      enable_if_t<(_Ip < sizeof...(_Types)), int> = 0,
13970b57cec5SDimitry Andric      class _Tp = variant_alternative_t<_Ip, variant<_Types...>>,
13980b57cec5SDimitry Andric      enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
13990b57cec5SDimitry Andric                  int> = 0>
14000b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
14010b57cec5SDimitry Andric  _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
14020b57cec5SDimitry Andric    return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...);
14030b57cec5SDimitry Andric  }
14040b57cec5SDimitry Andric
14050b57cec5SDimitry Andric  template <
14060b57cec5SDimitry Andric      class _Tp,
14070b57cec5SDimitry Andric      class... _Args,
14080b57cec5SDimitry Andric      size_t _Ip =
14090b57cec5SDimitry Andric          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
14100b57cec5SDimitry Andric      enable_if_t<is_constructible_v<_Tp, _Args...>, int> = 0>
14110b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
14120b57cec5SDimitry Andric  _Tp& emplace(_Args&&... __args) {
14130b57cec5SDimitry Andric    return __impl.template __emplace<_Ip>(_VSTD::forward<_Args>(__args)...);
14140b57cec5SDimitry Andric  }
14150b57cec5SDimitry Andric
14160b57cec5SDimitry Andric  template <
14170b57cec5SDimitry Andric      class _Tp,
14180b57cec5SDimitry Andric      class _Up,
14190b57cec5SDimitry Andric      class... _Args,
14200b57cec5SDimitry Andric      size_t _Ip =
14210b57cec5SDimitry Andric          __find_detail::__find_unambiguous_index_sfinae<_Tp, _Types...>::value,
14220b57cec5SDimitry Andric      enable_if_t<is_constructible_v<_Tp, initializer_list<_Up>&, _Args...>,
14230b57cec5SDimitry Andric                  int> = 0>
14240b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
14250b57cec5SDimitry Andric  _Tp& emplace(initializer_list<_Up> __il, _Args&&... __args) {
14260b57cec5SDimitry Andric    return __impl.template __emplace<_Ip>(__il, _VSTD::forward<_Args>(__args)...);
14270b57cec5SDimitry Andric  }
14280b57cec5SDimitry Andric
14290b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
14300b57cec5SDimitry Andric  constexpr bool valueless_by_exception() const noexcept {
14310b57cec5SDimitry Andric    return __impl.valueless_by_exception();
14320b57cec5SDimitry Andric  }
14330b57cec5SDimitry Andric
14340b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
14350b57cec5SDimitry Andric  constexpr size_t index() const noexcept { return __impl.index(); }
14360b57cec5SDimitry Andric
14370b57cec5SDimitry Andric  template <
14380b57cec5SDimitry Andric      bool _Dummy = true,
14390b57cec5SDimitry Andric      enable_if_t<
14400b57cec5SDimitry Andric          __all<(
14410b57cec5SDimitry Andric              __dependent_type<is_move_constructible<_Types>, _Dummy>::value &&
14420b57cec5SDimitry Andric              __dependent_type<is_swappable<_Types>, _Dummy>::value)...>::value,
14430b57cec5SDimitry Andric          int> = 0>
14440b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
14450b57cec5SDimitry Andric  void swap(variant& __that) noexcept(
14460b57cec5SDimitry Andric      __all<(is_nothrow_move_constructible_v<_Types> &&
14470b57cec5SDimitry Andric             is_nothrow_swappable_v<_Types>)...>::value) {
14480b57cec5SDimitry Andric    __impl.__swap(__that.__impl);
14490b57cec5SDimitry Andric  }
14500b57cec5SDimitry Andric
14510b57cec5SDimitry Andricprivate:
14520b57cec5SDimitry Andric  __variant_detail::__impl<_Types...> __impl;
14530b57cec5SDimitry Andric
14540b57cec5SDimitry Andric  friend struct __variant_detail::__access::__variant;
14550b57cec5SDimitry Andric  friend struct __variant_detail::__visitation::__variant;
14560b57cec5SDimitry Andric};
14570b57cec5SDimitry Andric
14580b57cec5SDimitry Andrictemplate <size_t _Ip, class... _Types>
14590b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
14600b57cec5SDimitry Andricconstexpr bool __holds_alternative(const variant<_Types...>& __v) noexcept {
14610b57cec5SDimitry Andric  return __v.index() == _Ip;
14620b57cec5SDimitry Andric}
14630b57cec5SDimitry Andric
14640b57cec5SDimitry Andrictemplate <class _Tp, class... _Types>
14650b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
14660b57cec5SDimitry Andricconstexpr bool holds_alternative(const variant<_Types...>& __v) noexcept {
14670b57cec5SDimitry Andric  return __holds_alternative<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
14680b57cec5SDimitry Andric}
14690b57cec5SDimitry Andric
14700b57cec5SDimitry Andrictemplate <size_t _Ip, class _Vp>
14710b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
14720b57cec5SDimitry Andric_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
14730b57cec5SDimitry Andricconstexpr auto&& __generic_get(_Vp&& __v) {
14740b57cec5SDimitry Andric  using __variant_detail::__access::__variant;
14750b57cec5SDimitry Andric  if (!__holds_alternative<_Ip>(__v)) {
14760b57cec5SDimitry Andric    __throw_bad_variant_access();
14770b57cec5SDimitry Andric  }
14780b57cec5SDimitry Andric  return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value;
14790b57cec5SDimitry Andric}
14800b57cec5SDimitry Andric
14810b57cec5SDimitry Andrictemplate <size_t _Ip, class... _Types>
14820b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
14830b57cec5SDimitry Andric_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
14840b57cec5SDimitry Andricconstexpr variant_alternative_t<_Ip, variant<_Types...>>& get(
14850b57cec5SDimitry Andric    variant<_Types...>& __v) {
14860b57cec5SDimitry Andric  static_assert(_Ip < sizeof...(_Types));
14870b57cec5SDimitry Andric  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
14880b57cec5SDimitry Andric  return __generic_get<_Ip>(__v);
14890b57cec5SDimitry Andric}
14900b57cec5SDimitry Andric
14910b57cec5SDimitry Andrictemplate <size_t _Ip, class... _Types>
14920b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
14930b57cec5SDimitry Andric_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
14940b57cec5SDimitry Andricconstexpr variant_alternative_t<_Ip, variant<_Types...>>&& get(
14950b57cec5SDimitry Andric    variant<_Types...>&& __v) {
14960b57cec5SDimitry Andric  static_assert(_Ip < sizeof...(_Types));
14970b57cec5SDimitry Andric  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
14980b57cec5SDimitry Andric  return __generic_get<_Ip>(_VSTD::move(__v));
14990b57cec5SDimitry Andric}
15000b57cec5SDimitry Andric
15010b57cec5SDimitry Andrictemplate <size_t _Ip, class... _Types>
15020b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15030b57cec5SDimitry Andric_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
15040b57cec5SDimitry Andricconstexpr const variant_alternative_t<_Ip, variant<_Types...>>& get(
15050b57cec5SDimitry Andric    const variant<_Types...>& __v) {
15060b57cec5SDimitry Andric  static_assert(_Ip < sizeof...(_Types));
15070b57cec5SDimitry Andric  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
15080b57cec5SDimitry Andric  return __generic_get<_Ip>(__v);
15090b57cec5SDimitry Andric}
15100b57cec5SDimitry Andric
15110b57cec5SDimitry Andrictemplate <size_t _Ip, class... _Types>
15120b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15130b57cec5SDimitry Andric_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
15140b57cec5SDimitry Andricconstexpr const variant_alternative_t<_Ip, variant<_Types...>>&& get(
15150b57cec5SDimitry Andric    const variant<_Types...>&& __v) {
15160b57cec5SDimitry Andric  static_assert(_Ip < sizeof...(_Types));
15170b57cec5SDimitry Andric  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
15180b57cec5SDimitry Andric  return __generic_get<_Ip>(_VSTD::move(__v));
15190b57cec5SDimitry Andric}
15200b57cec5SDimitry Andric
15210b57cec5SDimitry Andrictemplate <class _Tp, class... _Types>
15220b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15230b57cec5SDimitry Andric_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
15240b57cec5SDimitry Andricconstexpr _Tp& get(variant<_Types...>& __v) {
15250b57cec5SDimitry Andric  static_assert(!is_void_v<_Tp>);
15260b57cec5SDimitry Andric  return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
15270b57cec5SDimitry Andric}
15280b57cec5SDimitry Andric
15290b57cec5SDimitry Andrictemplate <class _Tp, class... _Types>
15300b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15310b57cec5SDimitry Andric_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
15320b57cec5SDimitry Andricconstexpr _Tp&& get(variant<_Types...>&& __v) {
15330b57cec5SDimitry Andric  static_assert(!is_void_v<_Tp>);
15340b57cec5SDimitry Andric  return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(
15350b57cec5SDimitry Andric      _VSTD::move(__v));
15360b57cec5SDimitry Andric}
15370b57cec5SDimitry Andric
15380b57cec5SDimitry Andrictemplate <class _Tp, class... _Types>
15390b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15400b57cec5SDimitry Andric_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
15410b57cec5SDimitry Andricconstexpr const _Tp& get(const variant<_Types...>& __v) {
15420b57cec5SDimitry Andric  static_assert(!is_void_v<_Tp>);
15430b57cec5SDimitry Andric  return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
15440b57cec5SDimitry Andric}
15450b57cec5SDimitry Andric
15460b57cec5SDimitry Andrictemplate <class _Tp, class... _Types>
15470b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15480b57cec5SDimitry Andric_LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS
15490b57cec5SDimitry Andricconstexpr const _Tp&& get(const variant<_Types...>&& __v) {
15500b57cec5SDimitry Andric  static_assert(!is_void_v<_Tp>);
15510b57cec5SDimitry Andric  return _VSTD::get<__find_exactly_one_t<_Tp, _Types...>::value>(
15520b57cec5SDimitry Andric      _VSTD::move(__v));
15530b57cec5SDimitry Andric}
15540b57cec5SDimitry Andric
15550b57cec5SDimitry Andrictemplate <size_t _Ip, class _Vp>
15560b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15570b57cec5SDimitry Andricconstexpr auto* __generic_get_if(_Vp* __v) noexcept {
15580b57cec5SDimitry Andric  using __variant_detail::__access::__variant;
15590b57cec5SDimitry Andric  return __v && __holds_alternative<_Ip>(*__v)
15600b57cec5SDimitry Andric             ? _VSTD::addressof(__variant::__get_alt<_Ip>(*__v).__value)
15610b57cec5SDimitry Andric             : nullptr;
15620b57cec5SDimitry Andric}
15630b57cec5SDimitry Andric
15640b57cec5SDimitry Andrictemplate <size_t _Ip, class... _Types>
15650b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15660b57cec5SDimitry Andricconstexpr add_pointer_t<variant_alternative_t<_Ip, variant<_Types...>>>
15670b57cec5SDimitry Andricget_if(variant<_Types...>* __v) noexcept {
15680b57cec5SDimitry Andric  static_assert(_Ip < sizeof...(_Types));
15690b57cec5SDimitry Andric  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
15700b57cec5SDimitry Andric  return __generic_get_if<_Ip>(__v);
15710b57cec5SDimitry Andric}
15720b57cec5SDimitry Andric
15730b57cec5SDimitry Andrictemplate <size_t _Ip, class... _Types>
15740b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15750b57cec5SDimitry Andricconstexpr add_pointer_t<const variant_alternative_t<_Ip, variant<_Types...>>>
15760b57cec5SDimitry Andricget_if(const variant<_Types...>* __v) noexcept {
15770b57cec5SDimitry Andric  static_assert(_Ip < sizeof...(_Types));
15780b57cec5SDimitry Andric  static_assert(!is_void_v<variant_alternative_t<_Ip, variant<_Types...>>>);
15790b57cec5SDimitry Andric  return __generic_get_if<_Ip>(__v);
15800b57cec5SDimitry Andric}
15810b57cec5SDimitry Andric
15820b57cec5SDimitry Andrictemplate <class _Tp, class... _Types>
15830b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15840b57cec5SDimitry Andricconstexpr add_pointer_t<_Tp>
15850b57cec5SDimitry Andricget_if(variant<_Types...>* __v) noexcept {
15860b57cec5SDimitry Andric  static_assert(!is_void_v<_Tp>);
15870b57cec5SDimitry Andric  return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
15880b57cec5SDimitry Andric}
15890b57cec5SDimitry Andric
15900b57cec5SDimitry Andrictemplate <class _Tp, class... _Types>
15910b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
15920b57cec5SDimitry Andricconstexpr add_pointer_t<const _Tp>
15930b57cec5SDimitry Andricget_if(const variant<_Types...>* __v) noexcept {
15940b57cec5SDimitry Andric  static_assert(!is_void_v<_Tp>);
15950b57cec5SDimitry Andric  return _VSTD::get_if<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
15960b57cec5SDimitry Andric}
15970b57cec5SDimitry Andric
15980b57cec5SDimitry Andrictemplate <class _Operator>
15990b57cec5SDimitry Andricstruct __convert_to_bool {
16000b57cec5SDimitry Andric  template <class _T1, class _T2>
16010b57cec5SDimitry Andric  _LIBCPP_INLINE_VISIBILITY constexpr bool operator()(_T1 && __t1, _T2&& __t2) const {
1602e8d8bef9SDimitry Andric    static_assert(is_convertible<decltype(_Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2))), bool>::value,
16030b57cec5SDimitry Andric        "the relational operator does not return a type which is implicitly convertible to bool");
16040b57cec5SDimitry Andric    return _Operator{}(_VSTD::forward<_T1>(__t1), _VSTD::forward<_T2>(__t2));
16050b57cec5SDimitry Andric  }
16060b57cec5SDimitry Andric};
16070b57cec5SDimitry Andric
16080b57cec5SDimitry Andrictemplate <class... _Types>
16090b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
16100b57cec5SDimitry Andricconstexpr bool operator==(const variant<_Types...>& __lhs,
16110b57cec5SDimitry Andric                          const variant<_Types...>& __rhs) {
16120b57cec5SDimitry Andric  using __variant_detail::__visitation::__variant;
16130b57cec5SDimitry Andric  if (__lhs.index() != __rhs.index()) return false;
16140b57cec5SDimitry Andric  if (__lhs.valueless_by_exception()) return true;
16150b57cec5SDimitry Andric  return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<equal_to<>>{}, __lhs, __rhs);
16160b57cec5SDimitry Andric}
16170b57cec5SDimitry Andric
16180b57cec5SDimitry Andrictemplate <class... _Types>
16190b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
16200b57cec5SDimitry Andricconstexpr bool operator!=(const variant<_Types...>& __lhs,
16210b57cec5SDimitry Andric                          const variant<_Types...>& __rhs) {
16220b57cec5SDimitry Andric  using __variant_detail::__visitation::__variant;
16230b57cec5SDimitry Andric  if (__lhs.index() != __rhs.index()) return true;
16240b57cec5SDimitry Andric  if (__lhs.valueless_by_exception()) return false;
16250b57cec5SDimitry Andric  return __variant::__visit_value_at(
16260b57cec5SDimitry Andric      __lhs.index(), __convert_to_bool<not_equal_to<>>{}, __lhs, __rhs);
16270b57cec5SDimitry Andric}
16280b57cec5SDimitry Andric
16290b57cec5SDimitry Andrictemplate <class... _Types>
16300b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
16310b57cec5SDimitry Andricconstexpr bool operator<(const variant<_Types...>& __lhs,
16320b57cec5SDimitry Andric                         const variant<_Types...>& __rhs) {
16330b57cec5SDimitry Andric  using __variant_detail::__visitation::__variant;
16340b57cec5SDimitry Andric  if (__rhs.valueless_by_exception()) return false;
16350b57cec5SDimitry Andric  if (__lhs.valueless_by_exception()) return true;
16360b57cec5SDimitry Andric  if (__lhs.index() < __rhs.index()) return true;
16370b57cec5SDimitry Andric  if (__lhs.index() > __rhs.index()) return false;
16380b57cec5SDimitry Andric  return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<less<>>{}, __lhs, __rhs);
16390b57cec5SDimitry Andric}
16400b57cec5SDimitry Andric
16410b57cec5SDimitry Andrictemplate <class... _Types>
16420b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
16430b57cec5SDimitry Andricconstexpr bool operator>(const variant<_Types...>& __lhs,
16440b57cec5SDimitry Andric                         const variant<_Types...>& __rhs) {
16450b57cec5SDimitry Andric  using __variant_detail::__visitation::__variant;
16460b57cec5SDimitry Andric  if (__lhs.valueless_by_exception()) return false;
16470b57cec5SDimitry Andric  if (__rhs.valueless_by_exception()) return true;
16480b57cec5SDimitry Andric  if (__lhs.index() > __rhs.index()) return true;
16490b57cec5SDimitry Andric  if (__lhs.index() < __rhs.index()) return false;
16500b57cec5SDimitry Andric  return __variant::__visit_value_at(__lhs.index(), __convert_to_bool<greater<>>{}, __lhs, __rhs);
16510b57cec5SDimitry Andric}
16520b57cec5SDimitry Andric
16530b57cec5SDimitry Andrictemplate <class... _Types>
16540b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
16550b57cec5SDimitry Andricconstexpr bool operator<=(const variant<_Types...>& __lhs,
16560b57cec5SDimitry Andric                          const variant<_Types...>& __rhs) {
16570b57cec5SDimitry Andric  using __variant_detail::__visitation::__variant;
16580b57cec5SDimitry Andric  if (__lhs.valueless_by_exception()) return true;
16590b57cec5SDimitry Andric  if (__rhs.valueless_by_exception()) return false;
16600b57cec5SDimitry Andric  if (__lhs.index() < __rhs.index()) return true;
16610b57cec5SDimitry Andric  if (__lhs.index() > __rhs.index()) return false;
16620b57cec5SDimitry Andric  return __variant::__visit_value_at(
16630b57cec5SDimitry Andric      __lhs.index(), __convert_to_bool<less_equal<>>{}, __lhs, __rhs);
16640b57cec5SDimitry Andric}
16650b57cec5SDimitry Andric
16660b57cec5SDimitry Andrictemplate <class... _Types>
16670b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
16680b57cec5SDimitry Andricconstexpr bool operator>=(const variant<_Types...>& __lhs,
16690b57cec5SDimitry Andric                          const variant<_Types...>& __rhs) {
16700b57cec5SDimitry Andric  using __variant_detail::__visitation::__variant;
16710b57cec5SDimitry Andric  if (__rhs.valueless_by_exception()) return true;
16720b57cec5SDimitry Andric  if (__lhs.valueless_by_exception()) return false;
16730b57cec5SDimitry Andric  if (__lhs.index() > __rhs.index()) return true;
16740b57cec5SDimitry Andric  if (__lhs.index() < __rhs.index()) return false;
16750b57cec5SDimitry Andric  return __variant::__visit_value_at(
16760b57cec5SDimitry Andric      __lhs.index(), __convert_to_bool<greater_equal<>>{}, __lhs, __rhs);
16770b57cec5SDimitry Andric}
16780b57cec5SDimitry Andric
1679e8d8bef9SDimitry Andrictemplate <class... _Vs>
1680e8d8bef9SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
1681fe6060f1SDimitry Andric    _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr void
1682fe6060f1SDimitry Andric    __throw_if_valueless(_Vs&&... __vs) {
1683fe6060f1SDimitry Andric  const bool __valueless =
1684fe6060f1SDimitry Andric      (... || _VSTD::__as_variant(__vs).valueless_by_exception());
1685e8d8bef9SDimitry Andric  if (__valueless) {
1686e8d8bef9SDimitry Andric    __throw_bad_variant_access();
1687e8d8bef9SDimitry Andric  }
1688e8d8bef9SDimitry Andric}
1689e8d8bef9SDimitry Andric
1690fe6060f1SDimitry Andrictemplate <
1691fe6060f1SDimitry Andric    class _Visitor, class... _Vs,
1692fe6060f1SDimitry Andric    typename = void_t<decltype(_VSTD::__as_variant(declval<_Vs>()))...> >
16930b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
1694fe6060f1SDimitry Andric    _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr
1695fe6060f1SDimitry Andric    decltype(auto) visit(_Visitor&& __visitor, _Vs&&... __vs) {
16960b57cec5SDimitry Andric  using __variant_detail::__visitation::__variant;
1697e8d8bef9SDimitry Andric  _VSTD::__throw_if_valueless(_VSTD::forward<_Vs>(__vs)...);
16980b57cec5SDimitry Andric  return __variant::__visit_value(_VSTD::forward<_Visitor>(__visitor),
16990b57cec5SDimitry Andric                                  _VSTD::forward<_Vs>(__vs)...);
17000b57cec5SDimitry Andric}
17010b57cec5SDimitry Andric
1702e8d8bef9SDimitry Andric#if _LIBCPP_STD_VER > 17
1703fe6060f1SDimitry Andrictemplate <
1704fe6060f1SDimitry Andric    class _Rp, class _Visitor, class... _Vs,
1705fe6060f1SDimitry Andric    typename = void_t<decltype(_VSTD::__as_variant(declval<_Vs>()))...> >
1706e8d8bef9SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
1707fe6060f1SDimitry Andric    _LIBCPP_AVAILABILITY_THROW_BAD_VARIANT_ACCESS constexpr _Rp
1708fe6060f1SDimitry Andric    visit(_Visitor&& __visitor, _Vs&&... __vs) {
1709e8d8bef9SDimitry Andric  using __variant_detail::__visitation::__variant;
1710e8d8bef9SDimitry Andric  _VSTD::__throw_if_valueless(_VSTD::forward<_Vs>(__vs)...);
1711e8d8bef9SDimitry Andric  return __variant::__visit_value<_Rp>(_VSTD::forward<_Visitor>(__visitor),
1712e8d8bef9SDimitry Andric                                       _VSTD::forward<_Vs>(__vs)...);
1713e8d8bef9SDimitry Andric}
1714e8d8bef9SDimitry Andric#endif
1715e8d8bef9SDimitry Andric
17160b57cec5SDimitry Andrictemplate <class... _Types>
17170b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
1718*349cc55cSDimitry Andricauto swap(variant<_Types...>& __lhs, variant<_Types...>& __rhs)
1719*349cc55cSDimitry Andric  noexcept(noexcept(__lhs.swap(__rhs)))
1720*349cc55cSDimitry Andric  -> decltype(      __lhs.swap(__rhs))
1721*349cc55cSDimitry Andric  { return          __lhs.swap(__rhs); }
17220b57cec5SDimitry Andric
17230b57cec5SDimitry Andrictemplate <class... _Types>
17240b57cec5SDimitry Andricstruct _LIBCPP_TEMPLATE_VIS hash<
17250b57cec5SDimitry Andric    __enable_hash_helper<variant<_Types...>, remove_const_t<_Types>...>> {
17260b57cec5SDimitry Andric  using argument_type = variant<_Types...>;
17270b57cec5SDimitry Andric  using result_type = size_t;
17280b57cec5SDimitry Andric
17290b57cec5SDimitry Andric  inline _LIBCPP_INLINE_VISIBILITY
17300b57cec5SDimitry Andric  result_type operator()(const argument_type& __v) const {
17310b57cec5SDimitry Andric    using __variant_detail::__visitation::__variant;
17320b57cec5SDimitry Andric    size_t __res =
17330b57cec5SDimitry Andric        __v.valueless_by_exception()
17340b57cec5SDimitry Andric               ? 299792458 // Random value chosen by the universe upon creation
17350b57cec5SDimitry Andric               : __variant::__visit_alt(
17360b57cec5SDimitry Andric                     [](const auto& __alt) {
17370b57cec5SDimitry Andric                       using __alt_type = __uncvref_t<decltype(__alt)>;
17380b57cec5SDimitry Andric                       using __value_type = remove_const_t<
17390b57cec5SDimitry Andric                         typename __alt_type::__value_type>;
17400b57cec5SDimitry Andric                       return hash<__value_type>{}(__alt.__value);
17410b57cec5SDimitry Andric                     },
17420b57cec5SDimitry Andric                     __v);
17430b57cec5SDimitry Andric    return __hash_combine(__res, hash<size_t>{}(__v.index()));
17440b57cec5SDimitry Andric  }
17450b57cec5SDimitry Andric};
17460b57cec5SDimitry Andric
1747fe6060f1SDimitry Andric// __unchecked_get is the same as std::get, except, it is UB to use it with the wrong
1748fe6060f1SDimitry Andric// type whereas std::get will throw or returning nullptr. This makes it faster than
1749fe6060f1SDimitry Andric// std::get.
1750fe6060f1SDimitry Andrictemplate <size_t _Ip, class _Vp>
17510b57cec5SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
1752fe6060f1SDimitry Andricconstexpr auto&& __unchecked_get(_Vp&& __v) noexcept {
1753fe6060f1SDimitry Andric  using __variant_detail::__access::__variant;
1754fe6060f1SDimitry Andric  return __variant::__get_alt<_Ip>(_VSTD::forward<_Vp>(__v)).__value;
17550b57cec5SDimitry Andric}
1756fe6060f1SDimitry Andric
1757fe6060f1SDimitry Andrictemplate <class _Tp, class... _Types>
1758fe6060f1SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
1759fe6060f1SDimitry Andricconstexpr auto&& __unchecked_get(const variant<_Types...>& __v) noexcept {
1760fe6060f1SDimitry Andric  return __unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1761fe6060f1SDimitry Andric}
1762fe6060f1SDimitry Andric
1763fe6060f1SDimitry Andrictemplate <class _Tp, class... _Types>
1764fe6060f1SDimitry Andricinline _LIBCPP_INLINE_VISIBILITY
1765fe6060f1SDimitry Andricconstexpr auto&& __unchecked_get(variant<_Types...>& __v) noexcept {
1766fe6060f1SDimitry Andric  return __unchecked_get<__find_exactly_one_t<_Tp, _Types...>::value>(__v);
1767fe6060f1SDimitry Andric}
17680b57cec5SDimitry Andric
17690b57cec5SDimitry Andric#endif // _LIBCPP_STD_VER > 14
17700b57cec5SDimitry Andric
17710b57cec5SDimitry Andric_LIBCPP_END_NAMESPACE_STD
17720b57cec5SDimitry Andric
17730b57cec5SDimitry Andric_LIBCPP_POP_MACROS
17740b57cec5SDimitry Andric
17750b57cec5SDimitry Andric#endif // _LIBCPP_VARIANT
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