// -*- C++ -*-

//===----------------------------------------------------------------------===//

//

// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.

// See https://llvm.org/LICENSE.txt for license information.

// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

//

//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_TUPLE

#define _LIBCPP_TUPLE

// clang-format off

/*

    tuple synopsis

namespace std

{

template <class... T>

class tuple {

public:

    explicit(see-below) constexpr tuple();

    explicit(see-below) tuple(const T&...);  // constexpr in C++14

    template <class... U>

        explicit(see-below) tuple(U&&...);  // constexpr in C++14

    tuple(const tuple&) = default;

    tuple(tuple&&) = default;

    template<class... UTypes>

        constexpr explicit(see-below) tuple(tuple<UTypes...>&);  // C++23

    template <class... U>

        explicit(see-below) tuple(const tuple<U...>&);  // constexpr in C++14

    template <class... U>

        explicit(see-below) tuple(tuple<U...>&&);  // constexpr in C++14

    template<class... UTypes>

        constexpr explicit(see-below) tuple(const tuple<UTypes...>&&); // C++23

    template<class U1, class U2>

        constexpr explicit(see-below) tuple(pair<U1, U2>&);  // iff sizeof...(Types) == 2 // C++23

    template <class U1, class U2>

        explicit(see-below) tuple(const pair<U1, U2>&); // iff sizeof...(T) == 2 // constexpr in C++14

    template <class U1, class U2>

        explicit(see-below) tuple(pair<U1, U2>&&); // iff sizeof...(T) == 2  // constexpr in C++14

    template<class U1, class U2>

        constexpr explicit(see-below) tuple(const pair<U1, U2>&&);  // iff sizeof...(Types) == 2 // C++23

    // allocator-extended constructors

    template <class Alloc>

        tuple(allocator_arg_t, const Alloc& a);

    template <class Alloc>

        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const T&...);          // constexpr in C++20

    template <class Alloc, class... U>

        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, U&&...);               // constexpr in C++20

    template <class Alloc>

        tuple(allocator_arg_t, const Alloc& a, const tuple&);                             // constexpr in C++20

    template <class Alloc>

        tuple(allocator_arg_t, const Alloc& a, tuple&&);                                  // constexpr in C++20

    template<class Alloc, class... UTypes>

        constexpr explicit(see-below)

          tuple(allocator_arg_t, const Alloc& a, tuple<UTypes...>&);                      // C++23

    template <class Alloc, class... U>

        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const tuple<U...>&);   // constexpr in C++20

    template <class Alloc, class... U>

        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, tuple<U...>&&);        // constexpr in C++20

    template<class Alloc, class... UTypes>

        constexpr explicit(see-below)

          tuple(allocator_arg_t, const Alloc& a, const tuple<UTypes...>&&);               // C++23

    template<class Alloc, class U1, class U2>

        constexpr explicit(see-below)

          tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&);                          // C++23

    template <class Alloc, class U1, class U2>

        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&);  // constexpr in C++20

    template <class Alloc, class U1, class U2>

        explicit(see-below) tuple(allocator_arg_t, const Alloc& a, pair<U1, U2>&&);       // constexpr in C++20

    template<class Alloc, class U1, class U2>

        constexpr explicit(see-below)

          tuple(allocator_arg_t, const Alloc& a, const pair<U1, U2>&&);                   // C++23

    tuple& operator=(const tuple&);                                                       // constexpr in C++20

    constexpr const tuple& operator=(const tuple&) const;                                 // C++23

    tuple& operator=(tuple&&) noexcept(is_nothrow_move_assignable_v<T> && ...);           // constexpr in C++20

    constexpr const tuple& operator=(tuple&&) const;                                      // C++23

    template <class... U>

        tuple& operator=(const tuple<U...>&);                                             // constexpr in C++20

    template<class... UTypes>

        constexpr const tuple& operator=(const tuple<UTypes...>&) const;                  // C++23

    template <class... U>

        tuple& operator=(tuple<U...>&&);                                                  // constexpr in C++20

    template<class... UTypes>

        constexpr const tuple& operator=(tuple<UTypes...>&&) const;                       // C++23

    template <class U1, class U2>

        tuple& operator=(const pair<U1, U2>&); // iff sizeof...(T) == 2                   // constexpr in C++20

    template<class U1, class U2>

        constexpr const tuple& operator=(const pair<U1, U2>&) const;   // iff sizeof...(Types) == 2 // C++23

    template <class U1, class U2>

        tuple& operator=(pair<U1, U2>&&); // iff sizeof...(T) == 2                        // constexpr in C++20

    template<class U1, class U2>

        constexpr const tuple& operator=(pair<U1, U2>&&) const;  // iff sizeof...(Types) == 2 // C++23

    template<class U, size_t N>

        tuple& operator=(array<U, N> const&) // iff sizeof...(T) == N, EXTENSION

    template<class U, size_t N>

        tuple& operator=(array<U, N>&&) // iff sizeof...(T) == N, EXTENSION

    void swap(tuple&) noexcept(AND(swap(declval<T&>(), declval<T&>())...));               // constexpr in C++20

    constexpr void swap(const tuple&) const noexcept(see-below);                          // C++23

};

template<class... TTypes, class... UTypes, template<class> class TQual, template<class> class UQual> // since C++23

  requires requires { typename tuple<common_reference_t<TQual<TTypes>, UQual<UTypes>>...>; }

struct basic_common_reference<tuple<TTypes...>, tuple<UTypes...>, TQual, UQual> {

  using type = tuple<common_reference_t<TQual<TTypes>, UQual<UTypes>>...>;

};

template<class... TTypes, class... UTypes>                                // since C++23

  requires requires { typename tuple<common_type_t<TTypes, UTypes>...>; }

struct common_type<tuple<TTypes...>, tuple<UTypes...>> {

  using type = tuple<common_type_t<TTypes, UTypes>...>;

};

template <class ...T>

tuple(T...) -> tuple<T...>;                                         // since C++17

template <class T1, class T2>

tuple(pair<T1, T2>) -> tuple<T1, T2>;                               // since C++17

template <class Alloc, class ...T>

tuple(allocator_arg_t, Alloc, T...) -> tuple<T...>;                 // since C++17

template <class Alloc, class T1, class T2>

tuple(allocator_arg_t, Alloc, pair<T1, T2>) -> tuple<T1, T2>;       // since C++17

template <class Alloc, class ...T>

tuple(allocator_arg_t, Alloc, tuple<T...>) -> tuple<T...>;          // since C++17

inline constexpr unspecified ignore;

template <class... T> tuple<V...>  make_tuple(T&&...); // constexpr in C++14

template <class... T> tuple<ATypes...> forward_as_tuple(T&&...) noexcept; // constexpr in C++14

template <class... T> tuple<T&...> tie(T&...) noexcept; // constexpr in C++14

template <class... Tuples> tuple<CTypes...> tuple_cat(Tuples&&... tpls); // constexpr in C++14

// [tuple.apply], calling a function with a tuple of arguments:

template <class F, class Tuple>

  constexpr decltype(auto) apply(F&& f, Tuple&& t) noexcept(see below);  // C++17 noexcept since C++23

template <class T, class Tuple>

  constexpr T make_from_tuple(Tuple&& t); // C++17

// 20.4.1.4, tuple helper classes:

template <class T> struct tuple_size; // undefined

template <class... T> struct tuple_size<tuple<T...>>;

template <class T>

 inline constexpr size_t tuple_size_v = tuple_size<T>::value; // C++17

template <size_t I, class T> struct tuple_element; // undefined

template <size_t I, class... T> struct tuple_element<I, tuple<T...>>;

template <size_t I, class T>

  using tuple_element_t = typename tuple_element <I, T>::type; // C++14

// 20.4.1.5, element access:

template <size_t I, class... T>

    typename tuple_element<I, tuple<T...>>::type&

    get(tuple<T...>&) noexcept; // constexpr in C++14

template <size_t I, class... T>

    const typename tuple_element<I, tuple<T...>>::type&

    get(const tuple<T...>&) noexcept; // constexpr in C++14

template <size_t I, class... T>

    typename tuple_element<I, tuple<T...>>::type&&

    get(tuple<T...>&&) noexcept; // constexpr in C++14

template <size_t I, class... T>

    const typename tuple_element<I, tuple<T...>>::type&&

    get(const tuple<T...>&&) noexcept; // constexpr in C++14

template <class T1, class... T>

    constexpr T1& get(tuple<T...>&) noexcept;  // C++14

template <class T1, class... T>

    constexpr const T1& get(const tuple<T...>&) noexcept;   // C++14

template <class T1, class... T>

    constexpr T1&& get(tuple<T...>&&) noexcept;   // C++14

template <class T1, class... T>

    constexpr const T1&& get(const tuple<T...>&&) noexcept;   // C++14

// 20.4.1.6, relational operators:

template<class... T, class... U> bool operator==(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14

template<class... T, class... U> bool operator<(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14, removed in C++20

template<class... T, class... U> bool operator!=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20

template<class... T, class... U> bool operator>(const tuple<T...>&, const tuple<U...>&);  // constexpr in C++14, removed in C++20

template<class... T, class... U> bool operator<=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20

template<class... T, class... U> bool operator>=(const tuple<T...>&, const tuple<U...>&); // constexpr in C++14, removed in C++20

template<class... T, class... U>

  constexpr common_comparison_category_t<synth-three-way-result<T, U>...>

    operator<=>(const tuple<T...>&, const tuple<U...>&);                                  // since C++20

template <class... Types, class Alloc>

  struct uses_allocator<tuple<Types...>, Alloc>;

template <class... Types>

  void

  swap(tuple<Types...>& x, tuple<Types...>& y) noexcept(noexcept(x.swap(y)));

template <class... Types>

  constexpr void swap(const tuple<Types...>& x, const tuple<Types...>& y) noexcept(see-below);   // C++23

}  // std

*/

// clang-format on

#include <__assert> // all public C++ headers provide the assertion handler

#include <__compare/common_comparison_category.h>

#include <__compare/synth_three_way.h>

#include <__config>

#include <__functional/invoke.h>

#include <__fwd/array.h>

#include <__fwd/get.h>

#include <__fwd/tuple.h>

#include <__memory/allocator_arg_t.h>

#include <__memory/uses_allocator.h>

#include <__tuple/make_tuple_types.h>

#include <__tuple/sfinae_helpers.h>

#include <__tuple/tuple_element.h>

#include <__tuple/tuple_indices.h>

#include <__tuple/tuple_like_ext.h>

#include <__tuple/tuple_size.h>

#include <__tuple/tuple_types.h>

#include <__type_traits/apply_cv.h>

#include <__type_traits/common_reference.h>

#include <__type_traits/common_type.h>

#include <__type_traits/conditional.h>

#include <__type_traits/conjunction.h>

#include <__type_traits/copy_cvref.h>

#include <__type_traits/disjunction.h>

#include <__type_traits/is_arithmetic.h>

#include <__type_traits/is_assignable.h>

#include <__type_traits/is_constructible.h>

#include <__type_traits/is_convertible.h>

#include <__type_traits/is_copy_assignable.h>

#include <__type_traits/is_copy_constructible.h>

#include <__type_traits/is_default_constructible.h>

#include <__type_traits/is_empty.h>

#include <__type_traits/is_final.h>

#include <__type_traits/is_implicitly_default_constructible.h>

#include <__type_traits/is_move_assignable.h>

#include <__type_traits/is_move_constructible.h>

#include <__type_traits/is_nothrow_assignable.h>

#include <__type_traits/is_nothrow_constructible.h>

#include <__type_traits/is_nothrow_copy_assignable.h>

#include <__type_traits/is_nothrow_copy_constructible.h>

#include <__type_traits/is_nothrow_default_constructible.h>

#include <__type_traits/is_nothrow_move_assignable.h>

#include <__type_traits/is_reference.h>

#include <__type_traits/is_same.h>

#include <__type_traits/is_swappable.h>

#include <__type_traits/lazy.h>

#include <__type_traits/maybe_const.h>

#include <__type_traits/nat.h>

#include <__type_traits/negation.h>

#include <__type_traits/remove_cvref.h>

#include <__type_traits/remove_reference.h>

#include <__type_traits/unwrap_ref.h>

#include <__utility/forward.h>

#include <__utility/integer_sequence.h>

#include <__utility/move.h>

#include <__utility/pair.h>

#include <__utility/piecewise_construct.h>

#include <__utility/swap.h>

#include <cstddef>

#include <version>

// standard-mandated includes

// [tuple.syn]

#include <compare>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)

#  pragma GCC system_header

#endif

_LIBCPP_PUSH_MACROS

#include <__undef_macros>

_LIBCPP_BEGIN_NAMESPACE_STD

#ifndef _LIBCPP_CXX03_LANG

// __tuple_leaf

template <size_t _Ip, class _Hp, bool = is_empty<_Hp>::value && !__libcpp_is_final<_Hp>::value >

class __tuple_leaf;

template <size_t _Ip, class _Hp, bool _Ep>

inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void

swap(__tuple_leaf<_Ip, _Hp, _Ep>& __x, __tuple_leaf<_Ip, _Hp, _Ep>& __y)

    _NOEXCEPT_(__is_nothrow_swappable<_Hp>::value) {

  swap(__x.get(), __y.get());

}

template <size_t _Ip, class _Hp, bool _Ep>

_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void

swap(const __tuple_leaf<_Ip, _Hp, _Ep>& __x, const __tuple_leaf<_Ip, _Hp, _Ep>& __y)

    _NOEXCEPT_(__is_nothrow_swappable<const _Hp>::value) {

  swap(__x.get(), __y.get());

}

template <size_t _Ip, class _Hp, bool>

class __tuple_leaf {

  _Hp __value_;

  template <class _Tp>

  static _LIBCPP_HIDE_FROM_ABI constexpr bool __can_bind_reference() {

#  if __has_keyword(__reference_binds_to_temporary)

    return !__reference_binds_to_temporary(_Hp, _Tp);

#  else

    return true;

#  endif

  }

  _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_leaf& operator=(const __tuple_leaf&);

public:

  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf() _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) : __value_() {

    static_assert(!is_reference<_Hp>::value, "Attempted to default construct a reference element in a tuple");

  }

  template <class _Alloc>

  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 0>, const _Alloc&) : __value_() {

    static_assert(!is_reference<_Hp>::value, "Attempted to default construct a reference element in a tuple");

  }

  template <class _Alloc>

  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)

      : __value_(allocator_arg_t(), __a) {

    static_assert(!is_reference<_Hp>::value, "Attempted to default construct a reference element in a tuple");

  }

  template <class _Alloc>

  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a) : __value_(__a) {

    static_assert(!is_reference<_Hp>::value, "Attempted to default construct a reference element in a tuple");

  }

  template <class _Tp,

            class = __enable_if_t<

                _And< _IsNotSame<__remove_cvref_t<_Tp>, __tuple_leaf>, is_constructible<_Hp, _Tp> >::value > >

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_leaf(_Tp&& __t)

      _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))

      : __value_(std::forward<_Tp>(__t)) {

    static_assert(__can_bind_reference<_Tp&&>(),

                  "Attempted construction of reference element binds to a temporary whose lifetime has ended");

  }

  template <class _Tp, class _Alloc>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_leaf(

      integral_constant<int, 0>, const _Alloc&, _Tp&& __t)

      : __value_(std::forward<_Tp>(__t)) {

    static_assert(__can_bind_reference<_Tp&&>(),

                  "Attempted construction of reference element binds to a temporary whose lifetime has ended");

  }

  template <class _Tp, class _Alloc>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_leaf(

      integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)

      : __value_(allocator_arg_t(), __a, std::forward<_Tp>(__t)) {

    static_assert(!is_reference<_Hp>::value, "Attempted to uses-allocator construct a reference element in a tuple");

  }

  template <class _Tp, class _Alloc>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_leaf(

      integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)

      : __value_(std::forward<_Tp>(__t), __a) {

    static_assert(!is_reference<_Hp>::value, "Attempted to uses-allocator construct a reference element in a tuple");

  }

  _LIBCPP_HIDE_FROM_ABI __tuple_leaf(const __tuple_leaf& __t) = default;

  _LIBCPP_HIDE_FROM_ABI __tuple_leaf(__tuple_leaf&& __t)      = default;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 int swap(__tuple_leaf& __t)

      _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value) {

    std::swap(*this, __t);

    return 0;

  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 int swap(const __tuple_leaf& __t) const

      _NOEXCEPT_(__is_nothrow_swappable<const __tuple_leaf>::value) {

    std::swap(*this, __t);

    return 0;

  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Hp& get() _NOEXCEPT { return __value_; }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Hp& get() const _NOEXCEPT { return __value_; }

};

template <size_t _Ip, class _Hp>

class __tuple_leaf<_Ip, _Hp, true> : private _Hp {

  _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_leaf& operator=(const __tuple_leaf&);

public:

  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf() _NOEXCEPT_(is_nothrow_default_constructible<_Hp>::value) {}

  template <class _Alloc>

  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 0>, const _Alloc&) {}

  template <class _Alloc>

  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a)

      : _Hp(allocator_arg_t(), __a) {}

  template <class _Alloc>

  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a) : _Hp(__a) {}

  template <class _Tp,

            class = __enable_if_t<

                _And< _IsNotSame<__remove_cvref_t<_Tp>, __tuple_leaf>, is_constructible<_Hp, _Tp> >::value > >

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_leaf(_Tp&& __t)

      _NOEXCEPT_((is_nothrow_constructible<_Hp, _Tp>::value))

      : _Hp(std::forward<_Tp>(__t)) {}

  template <class _Tp, class _Alloc>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit __tuple_leaf(integral_constant<int, 0>, const _Alloc&, _Tp&& __t)

      : _Hp(std::forward<_Tp>(__t)) {}

  template <class _Tp, class _Alloc>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit __tuple_leaf(integral_constant<int, 1>, const _Alloc& __a, _Tp&& __t)

      : _Hp(allocator_arg_t(), __a, std::forward<_Tp>(__t)) {}

  template <class _Tp, class _Alloc>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit __tuple_leaf(integral_constant<int, 2>, const _Alloc& __a, _Tp&& __t)

      : _Hp(std::forward<_Tp>(__t), __a) {}

  __tuple_leaf(__tuple_leaf const&) = default;

  __tuple_leaf(__tuple_leaf&&)      = default;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 int swap(__tuple_leaf& __t)

      _NOEXCEPT_(__is_nothrow_swappable<__tuple_leaf>::value) {

    std::swap(*this, __t);

    return 0;

  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 int swap(const __tuple_leaf& __rhs) const

      _NOEXCEPT_(__is_nothrow_swappable<const __tuple_leaf>::value) {

    std::swap(*this, __rhs);

    return 0;

  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 _Hp& get() _NOEXCEPT { return static_cast<_Hp&>(*this); }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const _Hp& get() const _NOEXCEPT {

    return static_cast<const _Hp&>(*this);

  }

};

template <class... _Tp>

_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void __swallow(_Tp&&...) _NOEXCEPT {}

template <class _Tp>

struct __all_default_constructible;

template <class... _Tp>

struct __all_default_constructible<__tuple_types<_Tp...>> : __all<is_default_constructible<_Tp>::value...> {};

// __tuple_impl

template <class _Indx, class... _Tp>

struct __tuple_impl;

template <size_t... _Indx, class... _Tp>

struct _LIBCPP_DECLSPEC_EMPTY_BASES __tuple_impl<__tuple_indices<_Indx...>, _Tp...>

    : public __tuple_leaf<_Indx, _Tp>... {

  _LIBCPP_HIDE_FROM_ABI constexpr __tuple_impl()

      _NOEXCEPT_(__all<is_nothrow_default_constructible<_Tp>::value...>::value) {}

  template <size_t... _Uf, class... _Tf, size_t... _Ul, class... _Tl, class... _Up>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_impl(

      __tuple_indices<_Uf...>, __tuple_types<_Tf...>, __tuple_indices<_Ul...>, __tuple_types<_Tl...>, _Up&&... __u)

      _NOEXCEPT_((__all<is_nothrow_constructible<_Tf, _Up>::value...>::value &&

                  __all<is_nothrow_default_constructible<_Tl>::value...>::value))

      : __tuple_leaf<_Uf, _Tf>(std::forward<_Up>(__u))..., __tuple_leaf<_Ul, _Tl>()... {}

  template <class _Alloc, size_t... _Uf, class... _Tf, size_t... _Ul, class... _Tl, class... _Up>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit __tuple_impl(

      allocator_arg_t,

      const _Alloc& __a,

      __tuple_indices<_Uf...>,

      __tuple_types<_Tf...>,

      __tuple_indices<_Ul...>,

      __tuple_types<_Tl...>,

      _Up&&... __u)

      : __tuple_leaf<_Uf, _Tf>(__uses_alloc_ctor<_Tf, _Alloc, _Up>(), __a, std::forward<_Up>(__u))...,

        __tuple_leaf<_Ul, _Tl>(__uses_alloc_ctor<_Tl, _Alloc>(), __a)... {}

  template <class _Tuple, class = __enable_if_t<__tuple_constructible<_Tuple, tuple<_Tp...> >::value> >

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_impl(_Tuple&& __t) _NOEXCEPT_(

      (__all<is_nothrow_constructible<

           _Tp,

           typename tuple_element<_Indx, typename __make_tuple_types<_Tuple>::type>::type>::value...>::value))

      : __tuple_leaf<_Indx, _Tp>(

            std::forward<typename tuple_element<_Indx, typename __make_tuple_types<_Tuple>::type>::type>(

                std::get<_Indx>(__t)))... {}

  template <class _Alloc, class _Tuple, class = __enable_if_t<__tuple_constructible<_Tuple, tuple<_Tp...> >::value> >

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 __tuple_impl(allocator_arg_t, const _Alloc& __a, _Tuple&& __t)

      : __tuple_leaf<_Indx, _Tp>(

            __uses_alloc_ctor<_Tp,

                              _Alloc,

                              typename tuple_element<_Indx, typename __make_tuple_types<_Tuple>::type>::type>(),

            __a,

            std::forward<typename tuple_element<_Indx, typename __make_tuple_types<_Tuple>::type>::type>(

                std::get<_Indx>(__t)))... {}

  __tuple_impl(const __tuple_impl&) = default;

  __tuple_impl(__tuple_impl&&)      = default;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void swap(__tuple_impl& __t)

      _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value) {

    std::__swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<__tuple_leaf<_Indx, _Tp>&>(__t))...);

  }

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void swap(const __tuple_impl& __t) const

      _NOEXCEPT_(__all<__is_nothrow_swappable<const _Tp>::value...>::value) {

    std::__swallow(__tuple_leaf<_Indx, _Tp>::swap(static_cast<const __tuple_leaf<_Indx, _Tp>&>(__t))...);

  }

};

template <class _Dest, class _Source, size_t... _Np>

_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void

__memberwise_copy_assign(_Dest& __dest, _Source const& __source, __tuple_indices<_Np...>) {

  std::__swallow(((std::get<_Np>(__dest) = std::get<_Np>(__source)), void(), 0)...);

}

template <class _Dest, class _Source, class... _Up, size_t... _Np>

_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 void

__memberwise_forward_assign(_Dest& __dest, _Source&& __source, __tuple_types<_Up...>, __tuple_indices<_Np...>) {

  std::__swallow(((std::get<_Np>(__dest) = std::forward<_Up>(std::get<_Np>(__source))), void(), 0)...);

}

template <class... _Tp>

class _LIBCPP_TEMPLATE_VIS tuple {

  typedef __tuple_impl<typename __make_tuple_indices<sizeof...(_Tp)>::type, _Tp...> _BaseT;

  _BaseT __base_;

  template <size_t _Jp, class... _Up>

  friend _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Jp, tuple<_Up...> >::type& get(tuple<_Up...>&) _NOEXCEPT;

  template <size_t _Jp, class... _Up>

  friend _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Jp, tuple<_Up...> >::type&

  get(const tuple<_Up...>&) _NOEXCEPT;

  template <size_t _Jp, class... _Up>

  friend _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Jp, tuple<_Up...> >::type&&

  get(tuple<_Up...>&&) _NOEXCEPT;

  template <size_t _Jp, class... _Up>

  friend _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Jp, tuple<_Up...> >::type&&

  get(const tuple<_Up...>&&) _NOEXCEPT;

public:

  // [tuple.cnstr]

  _LIBCPP_DIAGNOSTIC_PUSH

  _LIBCPP_CLANG_DIAGNOSTIC_IGNORED("-Wc++20-extensions")

  _LIBCPP_GCC_DIAGNOSTIC_IGNORED("-Wc++20-extensions")

  // tuple() constructors (including allocator_arg_t variants)

  template <template <class...> class _IsImpDefault                = __is_implicitly_default_constructible,

            template <class...> class _IsDefault                   = is_default_constructible,

            __enable_if_t< _And< _IsDefault<_Tp>... >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit(_Not<_Lazy<_And, _IsImpDefault<_Tp>...> >::value) tuple()

      _NOEXCEPT_(_And<is_nothrow_default_constructible<_Tp>...>::value) {}

  template <class _Alloc,

            template <class...> class _IsImpDefault                = __is_implicitly_default_constructible,

            template <class...> class _IsDefault                   = is_default_constructible,

            __enable_if_t< _And< _IsDefault<_Tp>... >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(_Not<_Lazy<_And, _IsImpDefault<_Tp>...> >::value)

      tuple(allocator_arg_t, _Alloc const& __a)

      : __base_(allocator_arg_t(),

                __a,

                __tuple_indices<>(),

                __tuple_types<>(),

                typename __make_tuple_indices<sizeof...(_Tp), 0>::type(),

                __tuple_types<_Tp...>()) {}

  // tuple(const T&...) constructors (including allocator_arg_t variants)

  template <template <class...> class _And = _And,

            __enable_if_t< _And< _BoolConstant<sizeof...(_Tp) >= 1>, is_copy_constructible<_Tp>... >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(

      _Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> >::value) tuple(const _Tp&... __t)

      _NOEXCEPT_(_And<is_nothrow_copy_constructible<_Tp>...>::value)

      : __base_(typename __make_tuple_indices<sizeof...(_Tp)>::type(),

                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),

                typename __make_tuple_indices<0>::type(),

                typename __make_tuple_types<tuple, 0>::type(),

                __t...) {}

  template <class _Alloc,

            template <class...> class _And = _And,

            __enable_if_t< _And< _BoolConstant<sizeof...(_Tp) >= 1>, is_copy_constructible<_Tp>... >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(

      _Not<_Lazy<_And, is_convertible<const _Tp&, _Tp>...> >::value)

      tuple(allocator_arg_t, const _Alloc& __a, const _Tp&... __t)

      : __base_(allocator_arg_t(),

                __a,

                typename __make_tuple_indices<sizeof...(_Tp)>::type(),

                typename __make_tuple_types<tuple, sizeof...(_Tp)>::type(),

                typename __make_tuple_indices<0>::type(),

                typename __make_tuple_types<tuple, 0>::type(),

                __t...) {}

  // tuple(U&& ...) constructors (including allocator_arg_t variants)

  template <class... _Up>

  struct _IsThisTuple : false_type {};

  template <class _Up>

  struct _IsThisTuple<_Up> : is_same<__remove_cvref_t<_Up>, tuple> {};

  template <class... _Up>

  struct _EnableUTypesCtor

      : _And< _BoolConstant<sizeof...(_Tp) >= 1>,

              _Not<_IsThisTuple<_Up...> >, // extension to allow mis-behaved user constructors

              is_constructible<_Tp, _Up>... > {};

  template <class... _Up,

            __enable_if_t< _And< _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>, _EnableUTypesCtor<_Up...> >::value,

                           int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(_Not<_Lazy<_And, is_convertible<_Up, _Tp>...> >::value)

      tuple(_Up&&... __u) _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))

      : __base_(typename __make_tuple_indices<sizeof...(_Up)>::type(),

                typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),

                typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),

                typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),

                std::forward<_Up>(__u)...) {}

  template <class _Alloc,

            class... _Up,

            __enable_if_t< _And< _BoolConstant<sizeof...(_Up) == sizeof...(_Tp)>, _EnableUTypesCtor<_Up...> >::value,

                           int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(_Not<_Lazy<_And, is_convertible<_Up, _Tp>...> >::value)

      tuple(allocator_arg_t, const _Alloc& __a, _Up&&... __u)

      : __base_(allocator_arg_t(),

                __a,

                typename __make_tuple_indices<sizeof...(_Up)>::type(),

                typename __make_tuple_types<tuple, sizeof...(_Up)>::type(),

                typename __make_tuple_indices<sizeof...(_Tp), sizeof...(_Up)>::type(),

                typename __make_tuple_types<tuple, sizeof...(_Tp), sizeof...(_Up)>::type(),

                std::forward<_Up>(__u)...) {}

  // Copy and move constructors (including the allocator_arg_t variants)

  tuple(const tuple&) = default;

  tuple(tuple&&)      = default;

  template <class _Alloc,

            template <class...> class _And                                  = _And,

            __enable_if_t< _And<is_copy_constructible<_Tp>...>::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(allocator_arg_t, const _Alloc& __alloc, const tuple& __t)

      : __base_(allocator_arg_t(), __alloc, __t) {}

  template <class _Alloc,

            template <class...> class _And                                  = _And,

            __enable_if_t< _And<is_move_constructible<_Tp>...>::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(allocator_arg_t, const _Alloc& __alloc, tuple&& __t)

      : __base_(allocator_arg_t(), __alloc, std::move(__t)) {}

  // tuple(const tuple<U...>&) constructors (including allocator_arg_t variants)

  template <class _OtherTuple, class _DecayedOtherTuple = __remove_cvref_t<_OtherTuple>, class = void>

  struct _EnableCtorFromUTypesTuple : false_type {};

  template <class _OtherTuple, class... _Up>

  struct _EnableCtorFromUTypesTuple<

      _OtherTuple,

      tuple<_Up...>,

      // the length of the packs needs to checked first otherwise the 2 packs cannot be expanded simultaneously below

      __enable_if_t<sizeof...(_Up) == sizeof...(_Tp)>>

      : _And<

            // the two conditions below are not in spec. The purpose is to disable the UTypes Ctor when copy/move Ctor

            // can work. Otherwise, is_constructible can trigger hard error in those cases

            // https://godbolt.org/z/M94cGdKcE

            _Not<is_same<_OtherTuple, const tuple&> >,

            _Not<is_same<_OtherTuple, tuple&&> >,

            is_constructible<_Tp, __copy_cvref_t<_OtherTuple, _Up> >...,

            _Lazy<_Or,

                  _BoolConstant<sizeof...(_Tp) != 1>,

                  // _Tp and _Up are 1-element packs - the pack expansions look

                  // weird to avoid tripping up the type traits in degenerate cases

                  _Lazy<_And,

                        _Not<is_same<_Tp, _Up> >...,

                        _Not<is_convertible<_OtherTuple, _Tp> >...,

                        _Not<is_constructible<_Tp, _OtherTuple> >... > > > {};

  template <class... _Up, __enable_if_t< _And< _EnableCtorFromUTypesTuple<const tuple<_Up...>&> >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(

      _Not<_Lazy<_And, is_convertible<const _Up&, _Tp>...> >::value) tuple(const tuple<_Up...>& __t)

      _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, const _Up&>...>::value))

      : __base_(__t) {}

  template <class... _Up,

            class _Alloc,

            __enable_if_t< _And< _EnableCtorFromUTypesTuple<const tuple<_Up...>&> >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(

      _Not<_Lazy<_And, is_convertible<const _Up&, _Tp>...> >::value)

      tuple(allocator_arg_t, const _Alloc& __a, const tuple<_Up...>& __t)

      : __base_(allocator_arg_t(), __a, __t) {}

#  if _LIBCPP_STD_VER >= 23

  // tuple(tuple<U...>&) constructors (including allocator_arg_t variants)

  template <class... _Up, enable_if_t< _EnableCtorFromUTypesTuple<tuple<_Up...>&>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_Lazy<_And, is_convertible<_Up&, _Tp>...>::value) tuple(tuple<_Up...>& __t)

      : __base_(__t) {}

  template <class _Alloc, class... _Up, enable_if_t< _EnableCtorFromUTypesTuple<tuple<_Up...>&>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_Lazy<_And, is_convertible<_Up&, _Tp>...>::value)

      tuple(allocator_arg_t, const _Alloc& __alloc, tuple<_Up...>& __t)

      : __base_(allocator_arg_t(), __alloc, __t) {}

#  endif // _LIBCPP_STD_VER >= 23

  // tuple(tuple<U...>&&) constructors (including allocator_arg_t variants)

  template <class... _Up, __enable_if_t< _And< _EnableCtorFromUTypesTuple<tuple<_Up...>&&> >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(_Not<_Lazy<_And, is_convertible<_Up, _Tp>...> >::value)

      tuple(tuple<_Up...>&& __t) _NOEXCEPT_((_And<is_nothrow_constructible<_Tp, _Up>...>::value))

      : __base_(std::move(__t)) {}

  template <class _Alloc,

            class... _Up,

            __enable_if_t< _And< _EnableCtorFromUTypesTuple<tuple<_Up...>&&> >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(_Not<_Lazy<_And, is_convertible<_Up, _Tp>...> >::value)

      tuple(allocator_arg_t, const _Alloc& __a, tuple<_Up...>&& __t)

      : __base_(allocator_arg_t(), __a, std::move(__t)) {}

#  if _LIBCPP_STD_VER >= 23

  // tuple(const tuple<U...>&&) constructors (including allocator_arg_t variants)

  template <class... _Up, enable_if_t< _EnableCtorFromUTypesTuple<const tuple<_Up...>&&>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_Lazy<_And, is_convertible<const _Up&&, _Tp>...>::value)

      tuple(const tuple<_Up...>&& __t)

      : __base_(std::move(__t)) {}

  template <class _Alloc,

            class... _Up,

            enable_if_t< _EnableCtorFromUTypesTuple<const tuple<_Up...>&&>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_Lazy<_And, is_convertible<const _Up&&, _Tp>...>::value)

      tuple(allocator_arg_t, const _Alloc& __alloc, const tuple<_Up...>&& __t)

      : __base_(allocator_arg_t(), __alloc, std::move(__t)) {}

#  endif // _LIBCPP_STD_VER >= 23

  // tuple(const pair<U1, U2>&) constructors (including allocator_arg_t variants)

  template <template <class...> class _Pred,

            class _Pair,

            class _DecayedPair = __remove_cvref_t<_Pair>,

            class _Tuple       = tuple>

  struct _CtorPredicateFromPair : false_type {};

  template <template <class...> class _Pred, class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>

  struct _CtorPredicateFromPair<_Pred, _Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> >

      : _And< _Pred<_Tp1, __copy_cvref_t<_Pair, _Up1> >, _Pred<_Tp2, __copy_cvref_t<_Pair, _Up2> > > {};

  template <class _Pair>

  struct _EnableCtorFromPair : _CtorPredicateFromPair<is_constructible, _Pair> {};

  template <class _Pair>

  struct _NothrowConstructibleFromPair : _CtorPredicateFromPair<is_nothrow_constructible, _Pair> {};

  template <class _Pair, class _DecayedPair = __remove_cvref_t<_Pair>, class _Tuple = tuple>

  struct _BothImplicitlyConvertible : false_type {};

  template <class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>

  struct _BothImplicitlyConvertible<_Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> >

      : _And< is_convertible<__copy_cvref_t<_Pair, _Up1>, _Tp1>, is_convertible<__copy_cvref_t<_Pair, _Up2>, _Tp2> > {};

  template <class _Up1,

            class _Up2,

            template <class...> class _And                                                   = _And,

            __enable_if_t< _And< _EnableCtorFromPair<const pair<_Up1, _Up2>&> >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(

      _Not<_BothImplicitlyConvertible<const pair<_Up1, _Up2>&> >::value) tuple(const pair<_Up1, _Up2>& __p)

      _NOEXCEPT_((_NothrowConstructibleFromPair<const pair<_Up1, _Up2>&>::value))

      : __base_(__p) {}

  template <class _Alloc,

            class _Up1,

            class _Up2,

            template <class...> class _And                                                   = _And,

            __enable_if_t< _And< _EnableCtorFromPair<const pair<_Up1, _Up2>&> >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(

      _Not<_BothImplicitlyConvertible<const pair<_Up1, _Up2>&> >::value)

      tuple(allocator_arg_t, const _Alloc& __a, const pair<_Up1, _Up2>& __p)

      : __base_(allocator_arg_t(), __a, __p) {}

#  if _LIBCPP_STD_VER >= 23

  // tuple(pair<U1, U2>&) constructors (including allocator_arg_t variants)

  template <class _U1, class _U2, enable_if_t< _EnableCtorFromPair<pair<_U1, _U2>&>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_BothImplicitlyConvertible<pair<_U1, _U2>&>::value)

      tuple(pair<_U1, _U2>& __p)

      : __base_(__p) {}

  template <class _Alloc,

            class _U1,

            class _U2,

            enable_if_t< _EnableCtorFromPair<std::pair<_U1, _U2>&>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_BothImplicitlyConvertible<pair<_U1, _U2>&>::value)

      tuple(allocator_arg_t, const _Alloc& __alloc, pair<_U1, _U2>& __p)

      : __base_(allocator_arg_t(), __alloc, __p) {}

#  endif

  // tuple(pair<U1, U2>&&) constructors (including allocator_arg_t variants)

  template <class _Up1,

            class _Up2,

            template <class...> class _And                                              = _And,

            __enable_if_t< _And< _EnableCtorFromPair<pair<_Up1, _Up2>&&> >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 explicit(

      _Not<_BothImplicitlyConvertible<pair<_Up1, _Up2>&&> >::value) tuple(pair<_Up1, _Up2>&& __p)

      _NOEXCEPT_((_NothrowConstructibleFromPair<pair<_Up1, _Up2>&&>::value))

      : __base_(std::move(__p)) {}

  template <class _Alloc,

            class _Up1,

            class _Up2,

            template <class...> class _And                                              = _And,

            __enable_if_t< _And< _EnableCtorFromPair<pair<_Up1, _Up2>&&> >::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit(

      _Not<_BothImplicitlyConvertible<pair<_Up1, _Up2>&&> >::value)

      tuple(allocator_arg_t, const _Alloc& __a, pair<_Up1, _Up2>&& __p)

      : __base_(allocator_arg_t(), __a, std::move(__p)) {}

#  if _LIBCPP_STD_VER >= 23

  // tuple(const pair<U1, U2>&&) constructors (including allocator_arg_t variants)

  template <class _U1, class _U2, enable_if_t< _EnableCtorFromPair<const pair<_U1, _U2>&&>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_BothImplicitlyConvertible<const pair<_U1, _U2>&&>::value)

      tuple(const pair<_U1, _U2>&& __p)

      : __base_(std::move(__p)) {}

  template <class _Alloc,

            class _U1,

            class _U2,

            enable_if_t< _EnableCtorFromPair<const pair<_U1, _U2>&&>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr explicit(!_BothImplicitlyConvertible<const pair<_U1, _U2>&&>::value)

      tuple(allocator_arg_t, const _Alloc& __alloc, const pair<_U1, _U2>&& __p)

      : __base_(allocator_arg_t(), __alloc, std::move(__p)) {}

#  endif // _LIBCPP_STD_VER >= 23

  _LIBCPP_DIAGNOSTIC_POP

  // [tuple.assign]

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple&

  operator=(_If<_And<is_copy_assignable<_Tp>...>::value, tuple, __nat> const& __tuple)

      _NOEXCEPT_((_And<is_nothrow_copy_assignable<_Tp>...>::value)) {

    std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());

    return *this;

  }

#  if _LIBCPP_STD_VER >= 23

  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(tuple const& __tuple) const

    requires(_And<is_copy_assignable<const _Tp>...>::value)

  {

    std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());

    return *this;

  }

  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(tuple&& __tuple) const

    requires(_And<is_assignable<const _Tp&, _Tp>...>::value)

  {

    std::__memberwise_forward_assign(

        *this, std::move(__tuple), __tuple_types<_Tp...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());

    return *this;

  }

#  endif // _LIBCPP_STD_VER >= 23

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple&

  operator=(_If<_And<is_move_assignable<_Tp>...>::value, tuple, __nat>&& __tuple)

      _NOEXCEPT_((_And<is_nothrow_move_assignable<_Tp>...>::value)) {

    std::__memberwise_forward_assign(

        *this, std::move(__tuple), __tuple_types<_Tp...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());

    return *this;

  }

  template <

      class... _Up,

      __enable_if_t< _And< _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>, is_assignable<_Tp&, _Up const&>... >::value,

                     int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(tuple<_Up...> const& __tuple)

      _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value)) {

    std::__memberwise_copy_assign(*this, __tuple, typename __make_tuple_indices<sizeof...(_Tp)>::type());

    return *this;

  }

  template <class... _Up,

            __enable_if_t< _And< _BoolConstant<sizeof...(_Tp) == sizeof...(_Up)>, is_assignable<_Tp&, _Up>... >::value,

                           int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(tuple<_Up...>&& __tuple)

      _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up>...>::value)) {

    std::__memberwise_forward_assign(

        *this, std::move(__tuple), __tuple_types<_Up...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());

    return *this;

  }

#  if _LIBCPP_STD_VER >= 23

  template <class... _UTypes,

            enable_if_t< _And<_BoolConstant<sizeof...(_Tp) == sizeof...(_UTypes)>,

                              is_assignable<const _Tp&, const _UTypes&>...>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(const tuple<_UTypes...>& __u) const {

    std::__memberwise_copy_assign(*this, __u, typename __make_tuple_indices<sizeof...(_Tp)>::type());

    return *this;

  }

  template <class... _UTypes,

            enable_if_t< _And<_BoolConstant<sizeof...(_Tp) == sizeof...(_UTypes)>,

                              is_assignable<const _Tp&, _UTypes>...>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(tuple<_UTypes...>&& __u) const {

    std::__memberwise_forward_assign(

        *this, __u, __tuple_types<_UTypes...>(), typename __make_tuple_indices<sizeof...(_Tp)>::type());

    return *this;

  }

#  endif // _LIBCPP_STD_VER >= 23

  template <template <class...> class _Pred,

            bool _Const,

            class _Pair,

            class _DecayedPair = __remove_cvref_t<_Pair>,

            class _Tuple       = tuple>

  struct _AssignPredicateFromPair : false_type {};

  template <template <class...> class _Pred, bool _Const, class _Pair, class _Up1, class _Up2, class _Tp1, class _Tp2>

  struct _AssignPredicateFromPair<_Pred, _Const, _Pair, pair<_Up1, _Up2>, tuple<_Tp1, _Tp2> >

      : _And<_Pred<__maybe_const<_Const, _Tp1>&, __copy_cvref_t<_Pair, _Up1> >,

             _Pred<__maybe_const<_Const, _Tp2>&, __copy_cvref_t<_Pair, _Up2> > > {};

  template <bool _Const, class _Pair>

  struct _EnableAssignFromPair : _AssignPredicateFromPair<is_assignable, _Const, _Pair> {};

  template <bool _Const, class _Pair>

  struct _NothrowAssignFromPair : _AssignPredicateFromPair<is_nothrow_assignable, _Const, _Pair> {};

#  if _LIBCPP_STD_VER >= 23

  template <class _U1, class _U2, enable_if_t< _EnableAssignFromPair<true, const pair<_U1, _U2>&>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(const pair<_U1, _U2>& __pair) const

      noexcept(_NothrowAssignFromPair<true, const pair<_U1, _U2>&>::value) {

    std::get<0>(*this) = __pair.first;

    std::get<1>(*this) = __pair.second;

    return *this;

  }

  template <class _U1, class _U2, enable_if_t< _EnableAssignFromPair<true, pair<_U1, _U2>&&>::value>* = nullptr>

  _LIBCPP_HIDE_FROM_ABI constexpr const tuple& operator=(pair<_U1, _U2>&& __pair) const

      noexcept(_NothrowAssignFromPair<true, pair<_U1, _U2>&&>::value) {

    std::get<0>(*this) = std::move(__pair.first);

    std::get<1>(*this) = std::move(__pair.second);

    return *this;

  }

#  endif // _LIBCPP_STD_VER >= 23

  template <class _Up1,

            class _Up2,

            __enable_if_t< _EnableAssignFromPair<false, pair<_Up1, _Up2> const&>::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(pair<_Up1, _Up2> const& __pair)

      _NOEXCEPT_((_NothrowAssignFromPair<false, pair<_Up1, _Up2> const&>::value)) {

    std::get<0>(*this) = __pair.first;

    std::get<1>(*this) = __pair.second;

    return *this;

  }

  template <class _Up1, class _Up2, __enable_if_t< _EnableAssignFromPair<false, pair<_Up1, _Up2>&&>::value, int> = 0>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(pair<_Up1, _Up2>&& __pair)

      _NOEXCEPT_((_NothrowAssignFromPair<false, pair<_Up1, _Up2>&&>::value)) {

    std::get<0>(*this) = std::forward<_Up1>(__pair.first);

    std::get<1>(*this) = std::forward<_Up2>(__pair.second);

    return *this;

  }

  // EXTENSION

  template <

      class _Up,

      size_t _Np,

      class = __enable_if_t< _And< _BoolConstant<_Np == sizeof...(_Tp)>, is_assignable<_Tp&, _Up const&>... >::value > >

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(array<_Up, _Np> const& __array)

      _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up const&>...>::value)) {

    std::__memberwise_copy_assign(*this, __array, typename __make_tuple_indices<sizeof...(_Tp)>::type());

    return *this;

  }

  // EXTENSION

  template <class _Up,

            size_t _Np,

            class = void,

            class = __enable_if_t< _And< _BoolConstant<_Np == sizeof...(_Tp)>, is_assignable<_Tp&, _Up>... >::value > >

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple& operator=(array<_Up, _Np>&& __array)

      _NOEXCEPT_((_And<is_nothrow_assignable<_Tp&, _Up>...>::value)) {

    std::__memberwise_forward_assign(

        *this,

        std::move(__array),

        __tuple_types<_If<true, _Up, _Tp>...>(),

        typename __make_tuple_indices<sizeof...(_Tp)>::type());

    return *this;

  }

  // [tuple.swap]

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(tuple& __t)

      _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value) {

    __base_.swap(__t.__base_);

  }

#  if _LIBCPP_STD_VER >= 23

  _LIBCPP_HIDE_FROM_ABI constexpr void swap(const tuple& __t) const

      noexcept(__all<is_nothrow_swappable_v<const _Tp&>...>::value) {

    __base_.swap(__t.__base_);

  }

#  endif // _LIBCPP_STD_VER >= 23

};

template <>

class _LIBCPP_TEMPLATE_VIS tuple<> {

public:

  constexpr tuple() _NOEXCEPT = default;

  template <class _Alloc>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(allocator_arg_t, const _Alloc&) _NOEXCEPT {}

  template <class _Alloc>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(allocator_arg_t, const _Alloc&, const tuple&) _NOEXCEPT {}

  template <class _Up>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(array<_Up, 0>) _NOEXCEPT {}

  template <class _Alloc, class _Up>

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 tuple(allocator_arg_t, const _Alloc&, array<_Up, 0>) _NOEXCEPT {}

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(tuple&) _NOEXCEPT {}

#  if _LIBCPP_STD_VER >= 23

  _LIBCPP_HIDE_FROM_ABI constexpr void swap(const tuple&) const noexcept {}

#  endif

};

#  if _LIBCPP_STD_VER >= 23

template <class... _TTypes, class... _UTypes, template <class> class _TQual, template <class> class _UQual>

  requires requires { typename tuple<common_reference_t<_TQual<_TTypes>, _UQual<_UTypes>>...>; }

struct basic_common_reference<tuple<_TTypes...>, tuple<_UTypes...>, _TQual, _UQual> {

  using type = tuple<common_reference_t<_TQual<_TTypes>, _UQual<_UTypes>>...>;

};

template <class... _TTypes, class... _UTypes>

  requires requires { typename tuple<common_type_t<_TTypes, _UTypes>...>; }

struct common_type<tuple<_TTypes...>, tuple<_UTypes...>> {

  using type = tuple<common_type_t<_TTypes, _UTypes>...>;

};

#  endif // _LIBCPP_STD_VER >= 23

#  if _LIBCPP_STD_VER >= 17

template <class... _Tp>

tuple(_Tp...) -> tuple<_Tp...>;

template <class _Tp1, class _Tp2>

tuple(pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;

template <class _Alloc, class... _Tp>

tuple(allocator_arg_t, _Alloc, _Tp...) -> tuple<_Tp...>;

template <class _Alloc, class _Tp1, class _Tp2>

tuple(allocator_arg_t, _Alloc, pair<_Tp1, _Tp2>) -> tuple<_Tp1, _Tp2>;

template <class _Alloc, class... _Tp>

tuple(allocator_arg_t, _Alloc, tuple<_Tp...>) -> tuple<_Tp...>;

#  endif

template <class... _Tp, __enable_if_t<__all<__is_swappable<_Tp>::value...>::value, int> = 0>

inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void swap(tuple<_Tp...>& __t, tuple<_Tp...>& __u)

    _NOEXCEPT_(__all<__is_nothrow_swappable<_Tp>::value...>::value) {

  __t.swap(__u);

}

#  if _LIBCPP_STD_VER >= 23

template <class... _Tp>

_LIBCPP_HIDE_FROM_ABI constexpr enable_if_t<__all<is_swappable_v<const _Tp>...>::value, void>

swap(const tuple<_Tp...>& __lhs,

     const tuple<_Tp...>& __rhs) noexcept(__all<is_nothrow_swappable_v<const _Tp>...>::value) {

  __lhs.swap(__rhs);

}

#  endif

// get

template <size_t _Ip, class... _Tp>

inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Ip, tuple<_Tp...> >::type&

get(tuple<_Tp...>& __t) _NOEXCEPT {

  typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;

  return static_cast<__tuple_leaf<_Ip, type>&>(__t.__base_).get();

}

template <size_t _Ip, class... _Tp>

inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Ip, tuple<_Tp...> >::type&

get(const tuple<_Tp...>& __t) _NOEXCEPT {

  typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;

  return static_cast<const __tuple_leaf<_Ip, type>&>(__t.__base_).get();

}

template <size_t _Ip, class... _Tp>

inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 typename tuple_element<_Ip, tuple<_Tp...> >::type&&

get(tuple<_Tp...>&& __t) _NOEXCEPT {

  typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;

  return static_cast<type&&>(static_cast<__tuple_leaf<_Ip, type>&&>(__t.__base_).get());

}

template <size_t _Ip, class... _Tp>

inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX14 const typename tuple_element<_Ip, tuple<_Tp...> >::type&&

get(const tuple<_Tp...>&& __t) _NOEXCEPT {

  typedef _LIBCPP_NODEBUG typename tuple_element<_Ip, tuple<_Tp...> >::type type;

  return static_cast<const type&&>(static_cast<const __tuple_leaf<_Ip, type>&&>(__t.__base_).get());

}

#  if _LIBCPP_STD_VER >= 14

namespace __find_detail {

static constexpr size_t __not_found = static_cast<size_t>(-1);

static constexpr size_t __ambiguous = __not_found - 1;

inline _LIBCPP_HIDE_FROM_ABI constexpr size_t __find_idx_return(size_t __curr_i, size_t __res, bool __matches) {

  return !__matches ? __res : (__res == __not_found ? __curr_i : __ambiguous);

}

template <size_t _Nx>

inline _LIBCPP_HIDE_FROM_ABI constexpr size_t __find_idx(size_t __i, const bool (&__matches)[_Nx]) {

  return __i == _Nx

           ? __not_found

           : __find_detail::__find_idx_return(__i, __find_detail::__find_idx(__i + 1, __matches), __matches[__i]);

}

template <class _T1, class... _Args>

struct __find_exactly_one_checked {

  static constexpr bool __matches[sizeof...(_Args)] = {is_same<_T1, _Args>::value...};

  static constexpr size_t value                     = __find_detail::__find_idx(0, __matches);

  static_assert(value != __not_found, "type not found in type list");

  static_assert(value != __ambiguous, "type occurs more than once in type list");

};

template <class _T1>

struct __find_exactly_one_checked<_T1> {

  static_assert(!is_same<_T1, _T1>::value, "type not in empty type list");

};

} // namespace __find_detail

template <typename _T1, typename... _Args>

struct __find_exactly_one_t : public __find_detail::__find_exactly_one_checked<_T1, _Args...> {};

template <class _T1, class... _Args>

inline _LIBCPP_HIDE_FROM_ABI constexpr _T1& get(tuple<_Args...>& __tup) noexcept {

  return std::get<__find_exactly_one_t<_T1, _Args...>::value>(__tup);

}