STL/stl/inc/utility

// utility standard header (core)

// Copyright (c) Microsoft Corporation.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#pragma once
#ifndef _UTILITY_
#define _UTILITY_
#include <yvals_core.h>
#if _STL_COMPILER_PREPROCESSOR
#include <type_traits>
#include <xstddef>

#ifdef __cpp_lib_concepts
#include <concepts>
#endif // __cpp_lib_concepts

#if _HAS_CXX20
#include <compare>
#endif // _HAS_CXX20

#pragma pack(push, _CRT_PACKING)
#pragma warning(push, _STL_WARNING_LEVEL)
#pragma warning(disable : _STL_DISABLED_WARNINGS)
_STL_DISABLE_CLANG_WARNINGS
#pragma push_macro("new")
#undef new

_STD_BEGIN
// FUNCTION TEMPLATE max
template <class _Ty, class _Pr>
_NODISCARD constexpr const _Ty&(max)(const _Ty& _Left, const _Ty& _Right, _Pr _Pred) noexcept(
    noexcept(_Pred(_Left, _Right))) /* strengthened */ {
    // return larger of _Left and _Right using _Pred
    return _Pred(_Left, _Right) ? _Right : _Left;
}

#pragma warning(push)
#pragma warning(disable : 28285) // (syntax error in SAL annotation, occurs when _Ty is not an integral type)
template <class _Ty>
_NODISCARD _Post_equal_to_(_Left < _Right ? _Right : _Left) constexpr const _Ty&(max)(
    const _Ty& _Left, const _Ty& _Right) noexcept(noexcept(_Left < _Right)) /* strengthened */ {
    // return larger of _Left and _Right
    return _Left < _Right ? _Right : _Left;
}
#pragma warning(pop)

template <class _Ty, class _Pr>
_NODISCARD constexpr _Ty(max)(initializer_list<_Ty>, _Pr); // implemented in <algorithm>

template <class _Ty>
_NODISCARD constexpr _Ty(max)(initializer_list<_Ty>); // implemented in <algorithm>


// FUNCTION TEMPLATE min
template <class _Ty, class _Pr>
_NODISCARD constexpr const _Ty&(min)(const _Ty& _Left, const _Ty& _Right, _Pr _Pred) noexcept(
    noexcept(_Pred(_Right, _Left))) /* strengthened */ {
    // return smaller of _Left and _Right using _Pred
    return _Pred(_Right, _Left) ? _Right : _Left;
}

#pragma warning(push)
#pragma warning(disable : 28285) // (syntax error in SAL annotation, occurs when _Ty is not an integral type)
template <class _Ty>
_NODISCARD _Post_equal_to_(_Right < _Left ? _Right : _Left) constexpr const _Ty&(min)(
    const _Ty& _Left, const _Ty& _Right) noexcept(noexcept(_Right < _Left)) /* strengthened */ {
    // return smaller of _Left and _Right
    return _Right < _Left ? _Right : _Left;
}
#pragma warning(pop)

template <class _Ty, class _Pr>
_NODISCARD constexpr _Ty(min)(initializer_list<_Ty>, _Pr); // implemented in <algorithm>

template <class _Ty>
_NODISCARD constexpr _Ty(min)(initializer_list<_Ty>); // implemented in <algorithm>


// FUNCTION TEMPLATE iter_swap (from <algorithm>)
template <class _FwdIt1, class _FwdIt2>
_CONSTEXPR20 void iter_swap(_FwdIt1 _Left, _FwdIt2 _Right) { // swap *_Left and *_Right
    swap(*_Left, *_Right);
}

// FUNCTION TEMPLATE swap
template <class _Ty, size_t _Size, enable_if_t<_Is_swappable<_Ty>::value, int> _Enabled>
_CONSTEXPR20 void swap(_Ty (&_Left)[_Size], _Ty (&_Right)[_Size]) noexcept(_Is_nothrow_swappable<_Ty>::value) {
    if (&_Left != &_Right) {
        _Ty* _First1 = _Left;
        _Ty* _Last1  = _First1 + _Size;
        _Ty* _First2 = _Right;
        for (; _First1 != _Last1; ++_First1, ++_First2) {
            _STD iter_swap(_First1, _First2);
        }
    }
}

#if _HAS_CXX17
template <class _Ty, enable_if_t<is_move_constructible_v<_Ty> && is_move_assignable_v<_Ty>, int> _Enabled>
#else // ^^^ _HAS_CXX17 / !_HAS_CXX17 vvv
template <class _Ty, int _Enabled>
#endif // _HAS_CXX17
_CONSTEXPR20 void swap(_Ty& _Left, _Ty& _Right) noexcept(
    is_nothrow_move_constructible_v<_Ty>&& is_nothrow_move_assignable_v<_Ty>) {
    _Ty _Tmp = _STD move(_Left);
    _Left    = _STD move(_Right);
    _Right   = _STD move(_Tmp);
}

// FUNCTION TEMPLATE _Swap_adl
template <class _Ty>
_CONSTEXPR20 void _Swap_adl(_Ty& _Left, _Ty& _Right) noexcept(_Is_nothrow_swappable<_Ty>::value) {
    swap(_Left, _Right);
}

// STRUCT piecewise_construct_t
struct piecewise_construct_t { // tag type for pair tuple arguments
    explicit piecewise_construct_t() = default;
};

_INLINE_VAR constexpr piecewise_construct_t piecewise_construct{};

// STRUCT TEMPLATE pair
template <class...>
class tuple;

template <class _Ty1, class _Ty2>
struct pair { // store a pair of values
    using first_type  = _Ty1;
    using second_type = _Ty2;

#if _HAS_CONDITIONAL_EXPLICIT
    template <class _Uty1 = _Ty1, class _Uty2 = _Ty2,
        enable_if_t<conjunction_v<is_default_constructible<_Uty1>, is_default_constructible<_Uty2>>, int> = 0>
    constexpr explicit(
        !_Is_implicitly_default_constructible<_Uty1>::value || !_Is_implicitly_default_constructible<_Uty2>::value)
        pair() noexcept(
            is_nothrow_default_constructible_v<_Uty1>&& is_nothrow_default_constructible_v<_Uty2>) // strengthened
        : first(), second() {}
#else // ^^^ _HAS_CONDITIONAL_EXPLICIT ^^^ / vvv !_HAS_CONDITIONAL_EXPLICIT vvv
    template <class _Uty1 = _Ty1, class _Uty2 = _Ty2,
        enable_if_t<conjunction_v<is_default_constructible<_Uty1>, is_default_constructible<_Uty2>,
                        _Is_implicitly_default_constructible<_Uty1>, _Is_implicitly_default_constructible<_Uty2>>,
            int> = 0>
    constexpr pair() noexcept(
        is_nothrow_default_constructible_v<_Uty1>&& is_nothrow_default_constructible_v<_Uty2>) // strengthened
        : first(), second() {}

    template <class _Uty1 = _Ty1, class _Uty2 = _Ty2,
        enable_if_t<conjunction_v<is_default_constructible<_Uty1>, is_default_constructible<_Uty2>,
                        negation<conjunction<_Is_implicitly_default_constructible<_Uty1>,
                            _Is_implicitly_default_constructible<_Uty2>>>>,
            int> = 0>
    constexpr explicit pair() noexcept(
        is_nothrow_default_constructible_v<_Uty1>&& is_nothrow_default_constructible_v<_Uty2>) // strengthened
        : first(), second() {}
#endif // ^^^ !_HAS_CONDITIONAL_EXPLICIT ^^^

#if _HAS_CONDITIONAL_EXPLICIT
    template <class _Uty1 = _Ty1, class _Uty2 = _Ty2,
        enable_if_t<conjunction_v<is_copy_constructible<_Uty1>, is_copy_constructible<_Uty2>>, int> = 0>
    constexpr explicit(!is_convertible_v<const _Uty1&, _Uty1> || !is_convertible_v<const _Uty2&, _Uty2>)
        pair(const _Ty1& _Val1, const _Ty2& _Val2) noexcept(
            is_nothrow_copy_constructible_v<_Uty1>&& is_nothrow_copy_constructible_v<_Uty2>) // strengthened
        : first(_Val1), second(_Val2) {}
#else // ^^^ _HAS_CONDITIONAL_EXPLICIT ^^^ / vvv !_HAS_CONDITIONAL_EXPLICIT vvv
    template <class _Uty1 = _Ty1, class _Uty2 = _Ty2,
        enable_if_t<conjunction_v<is_copy_constructible<_Uty1>, is_copy_constructible<_Uty2>,
                        is_convertible<const _Uty1&, _Uty1>, is_convertible<const _Uty2&, _Uty2>>,
            int> = 0>
    constexpr pair(const _Ty1& _Val1, const _Ty2& _Val2) noexcept(
        is_nothrow_copy_constructible_v<_Uty1>&& is_nothrow_copy_constructible_v<_Uty2>) // strengthened
        : first(_Val1), second(_Val2) {}

    template <class _Uty1 = _Ty1, class _Uty2 = _Ty2,
        enable_if_t<
            conjunction_v<is_copy_constructible<_Uty1>, is_copy_constructible<_Uty2>,
                negation<conjunction<is_convertible<const _Uty1&, _Uty1>, is_convertible<const _Uty2&, _Uty2>>>>,
            int> = 0>
    constexpr explicit pair(const _Ty1& _Val1, const _Ty2& _Val2) noexcept(
        is_nothrow_copy_constructible_v<_Uty1>&& is_nothrow_copy_constructible_v<_Uty2>) // strengthened
        : first(_Val1), second(_Val2) {}
#endif // ^^^ !_HAS_CONDITIONAL_EXPLICIT ^^^

#if _HAS_CONDITIONAL_EXPLICIT
    template <class _Other1, class _Other2,
        enable_if_t<conjunction_v<is_constructible<_Ty1, _Other1>, is_constructible<_Ty2, _Other2>>, int> = 0>
    constexpr explicit(!is_convertible_v<_Other1, _Ty1> || !is_convertible_v<_Other2, _Ty2>)
        pair(_Other1&& _Val1, _Other2&& _Val2) noexcept(
            is_nothrow_constructible_v<_Ty1, _Other1>&& is_nothrow_constructible_v<_Ty2, _Other2>) // strengthened
        : first(_STD forward<_Other1>(_Val1)), second(_STD forward<_Other2>(_Val2)) {}
#else // ^^^ _HAS_CONDITIONAL_EXPLICIT ^^^ / vvv !_HAS_CONDITIONAL_EXPLICIT vvv
    template <class _Other1, class _Other2,
        enable_if_t<conjunction_v<is_constructible<_Ty1, _Other1>, is_constructible<_Ty2, _Other2>,
                        is_convertible<_Other1, _Ty1>, is_convertible<_Other2, _Ty2>>,
            int> = 0>
    constexpr pair(_Other1&& _Val1, _Other2&& _Val2) noexcept(
        is_nothrow_constructible_v<_Ty1, _Other1>&& is_nothrow_constructible_v<_Ty2, _Other2>) // strengthened
        : first(_STD forward<_Other1>(_Val1)), second(_STD forward<_Other2>(_Val2)) {}

    template <class _Other1, class _Other2,
        enable_if_t<conjunction_v<is_constructible<_Ty1, _Other1>, is_constructible<_Ty2, _Other2>,
                        negation<conjunction<is_convertible<_Other1, _Ty1>, is_convertible<_Other2, _Ty2>>>>,
            int> = 0>
    constexpr explicit pair(_Other1&& _Val1, _Other2&& _Val2) noexcept(
        is_nothrow_constructible_v<_Ty1, _Other1>&& is_nothrow_constructible_v<_Ty2, _Other2>) // strengthened
        : first(_STD forward<_Other1>(_Val1)), second(_STD forward<_Other2>(_Val2)) {}
#endif // ^^^ !_HAS_CONDITIONAL_EXPLICIT ^^^

    pair(const pair&) = default;
    pair(pair&&)      = default;

#if _HAS_CONDITIONAL_EXPLICIT
    template <class _Other1, class _Other2,
        enable_if_t<conjunction_v<is_constructible<_Ty1, const _Other1&>, is_constructible<_Ty2, const _Other2&>>,
            int> = 0>
    constexpr explicit(!is_convertible_v<const _Other1&, _Ty1> || !is_convertible_v<const _Other2&, _Ty2>)
        pair(const pair<_Other1, _Other2>& _Right) noexcept(is_nothrow_constructible_v<_Ty1, const _Other1&>&&
                is_nothrow_constructible_v<_Ty2, const _Other2&>) // strengthened
        : first(_Right.first), second(_Right.second) {}
#else // ^^^ _HAS_CONDITIONAL_EXPLICIT ^^^ / vvv !_HAS_CONDITIONAL_EXPLICIT vvv
    template <class _Other1, class _Other2,
        enable_if_t<conjunction_v<is_constructible<_Ty1, const _Other1&>, is_constructible<_Ty2, const _Other2&>,
                        is_convertible<const _Other1&, _Ty1>, is_convertible<const _Other2&, _Ty2>>,
            int> = 0>
    constexpr pair(const pair<_Other1, _Other2>& _Right) noexcept(is_nothrow_constructible_v<_Ty1, const _Other1&>&&
            is_nothrow_constructible_v<_Ty2, const _Other2&>) // strengthened
        : first(_Right.first), second(_Right.second) {}

    template <class _Other1, class _Other2,
        enable_if_t<
            conjunction_v<is_constructible<_Ty1, const _Other1&>, is_constructible<_Ty2, const _Other2&>,
                negation<conjunction<is_convertible<const _Other1&, _Ty1>, is_convertible<const _Other2&, _Ty2>>>>,
            int> = 0>
    constexpr explicit pair(const pair<_Other1, _Other2>& _Right) noexcept(
        is_nothrow_constructible_v<_Ty1, const _Other1&>&&
            is_nothrow_constructible_v<_Ty2, const _Other2&>) // strengthened
        : first(_Right.first), second(_Right.second) {}
#endif // ^^^ !_HAS_CONDITIONAL_EXPLICIT ^^^

#if _HAS_CONDITIONAL_EXPLICIT
    template <class _Other1, class _Other2,
        enable_if_t<conjunction_v<is_constructible<_Ty1, _Other1>, is_constructible<_Ty2, _Other2>>, int> = 0>
    constexpr explicit(!is_convertible_v<_Other1, _Ty1> || !is_convertible_v<_Other2, _Ty2>)
        pair(pair<_Other1, _Other2>&& _Right) noexcept(
            is_nothrow_constructible_v<_Ty1, _Other1>&& is_nothrow_constructible_v<_Ty2, _Other2>) // strengthened
        : first(_STD forward<_Other1>(_Right.first)), second(_STD forward<_Other2>(_Right.second)) {}
#else // ^^^ _HAS_CONDITIONAL_EXPLICIT ^^^ / vvv !_HAS_CONDITIONAL_EXPLICIT vvv
    template <class _Other1, class _Other2,
        enable_if_t<conjunction_v<is_constructible<_Ty1, _Other1>, is_constructible<_Ty2, _Other2>,
                        is_convertible<_Other1, _Ty1>, is_convertible<_Other2, _Ty2>>,
            int> = 0>
    constexpr pair(pair<_Other1, _Other2>&& _Right) noexcept(
        is_nothrow_constructible_v<_Ty1, _Other1>&& is_nothrow_constructible_v<_Ty2, _Other2>) // strengthened
        : first(_STD forward<_Other1>(_Right.first)), second(_STD forward<_Other2>(_Right.second)) {}

    template <class _Other1, class _Other2,
        enable_if_t<conjunction_v<is_constructible<_Ty1, _Other1>, is_constructible<_Ty2, _Other2>,
                        negation<conjunction<is_convertible<_Other1, _Ty1>, is_convertible<_Other2, _Ty2>>>>,
            int> = 0>
    constexpr explicit pair(pair<_Other1, _Other2>&& _Right) noexcept(
        is_nothrow_constructible_v<_Ty1, _Other1>&& is_nothrow_constructible_v<_Ty2, _Other2>) // strengthened
        : first(_STD forward<_Other1>(_Right.first)), second(_STD forward<_Other2>(_Right.second)) {}
#endif // ^^^ !_HAS_CONDITIONAL_EXPLICIT ^^^

    template <class _Tuple1, class _Tuple2, size_t... _Indexes1, size_t... _Indexes2>
    pair(_Tuple1& _Val1, _Tuple2& _Val2, index_sequence<_Indexes1...>, index_sequence<_Indexes2...>);

    template <class... _Types1, class... _Types2>
    pair(piecewise_construct_t, tuple<_Types1...> _Val1, tuple<_Types2...> _Val2);

    pair& operator=(const volatile pair&) = delete;

    template <class _Myself = pair,
        enable_if_t<conjunction_v<_Is_copy_assignable_no_precondition_check<typename _Myself::first_type>,
                        _Is_copy_assignable_no_precondition_check<typename _Myself::second_type>>,
            int>            = 0>
    pair& operator=(_Identity_t<const _Myself&> _Right) noexcept(
        conjunction_v<is_nothrow_copy_assignable<_Ty1>, is_nothrow_copy_assignable<_Ty2>>) /* strengthened */ {

        first  = _Right.first;
        second = _Right.second;
        return *this;
    }

    template <class _Myself = pair,
        enable_if_t<conjunction_v<_Is_move_assignable_no_precondition_check<typename _Myself::first_type>,
                        _Is_move_assignable_no_precondition_check<typename _Myself::second_type>>,
            int>            = 0>
    pair& operator=(_Identity_t<_Myself&&> _Right) noexcept(
        conjunction_v<is_nothrow_move_assignable<_Ty1>, is_nothrow_move_assignable<_Ty2>>) /* strengthened */ {

        first  = _STD forward<_Ty1>(_Right.first);
        second = _STD forward<_Ty2>(_Right.second);
        return *this;
    }

    template <class _Other1, class _Other2,
        enable_if_t<conjunction_v<negation<is_same<pair, pair<_Other1, _Other2>>>, is_assignable<_Ty1&, const _Other1&>,
                        is_assignable<_Ty2&, const _Other2&>>,
            int> = 0>
    pair& operator=(const pair<_Other1, _Other2>& _Right) noexcept(is_nothrow_assignable_v<_Ty1&, const _Other1&>&&
            is_nothrow_assignable_v<_Ty2&, const _Other2&>) /* strengthened */ {

        first  = _Right.first;
        second = _Right.second;
        return *this;
    }

    template <class _Other1, class _Other2,
        enable_if_t<conjunction_v<negation<is_same<pair, pair<_Other1, _Other2>>>, is_assignable<_Ty1&, _Other1>,
                        is_assignable<_Ty2&, _Other2>>,
            int> = 0>
    pair& operator=(pair<_Other1, _Other2>&& _Right) noexcept(
        is_nothrow_assignable_v<_Ty1&, _Other1>&& is_nothrow_assignable_v<_Ty2&, _Other2>) /* strengthened */ {

        first  = _STD forward<_Other1>(_Right.first);
        second = _STD forward<_Other2>(_Right.second);
        return *this;
    }

    void swap(pair& _Right) noexcept(_Is_nothrow_swappable<_Ty1>::value&& _Is_nothrow_swappable<_Ty2>::value) {
        if (this != _STD addressof(_Right)) {
            _Swap_adl(first, _Right.first);
            _Swap_adl(second, _Right.second);
        }
    }

    _Ty1 first; // the first stored value
    _Ty2 second; // the second stored value
};

#if _HAS_CXX17
template <class _Ty1, class _Ty2>
pair(_Ty1, _Ty2) -> pair<_Ty1, _Ty2>;
#endif // _HAS_CXX17

template <class _Ty1, class _Ty2, enable_if_t<_Is_swappable<_Ty1>::value && _Is_swappable<_Ty2>::value, int> = 0>
void swap(pair<_Ty1, _Ty2>& _Left, pair<_Ty1, _Ty2>& _Right) noexcept(noexcept(_Left.swap(_Right))) {
    _Left.swap(_Right);
}

template <class _Ty1, class _Ty2>
_NODISCARD constexpr bool operator==(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
    return _Left.first == _Right.first && _Left.second == _Right.second;
}

template <class _Ty1, class _Ty2>
_NODISCARD constexpr bool operator!=(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
    return !(_Left == _Right);
}

template <class _Ty1, class _Ty2>
_NODISCARD constexpr bool operator<(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
    return _Left.first < _Right.first || (!(_Right.first < _Left.first) && _Left.second < _Right.second);
}

template <class _Ty1, class _Ty2>
_NODISCARD constexpr bool operator>(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
    return _Right < _Left;
}

template <class _Ty1, class _Ty2>
_NODISCARD constexpr bool operator<=(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
    return !(_Right < _Left);
}

template <class _Ty1, class _Ty2>
_NODISCARD constexpr bool operator>=(const pair<_Ty1, _Ty2>& _Left, const pair<_Ty1, _Ty2>& _Right) {
    return !(_Left < _Right);
}

// ALIAS TEMPLATE _Unrefwrap_t
template <class _Ty>
struct _Unrefwrap_helper { // leave unchanged if not a reference_wrapper
    using type = _Ty;
};

template <class _Ty>
struct _Unrefwrap_helper<reference_wrapper<_Ty>> { // make a reference from a reference_wrapper
    using type = _Ty&;
};

// decay, then unwrap a reference_wrapper
template <class _Ty>
using _Unrefwrap_t = typename _Unrefwrap_helper<decay_t<_Ty>>::type;

// FUNCTION TEMPLATE make_pair
template <class _Ty1, class _Ty2>
_NODISCARD constexpr pair<_Unrefwrap_t<_Ty1>, _Unrefwrap_t<_Ty2>> make_pair(_Ty1&& _Val1, _Ty2&& _Val2) noexcept(
    is_nothrow_constructible_v<_Unrefwrap_t<_Ty1>, _Ty1>&&
        is_nothrow_constructible_v<_Unrefwrap_t<_Ty2>, _Ty2>) /* strengthened */ {
    // return pair composed from arguments
    using _Mypair = pair<_Unrefwrap_t<_Ty1>, _Unrefwrap_t<_Ty2>>;
    return _Mypair(_STD forward<_Ty1>(_Val1), _STD forward<_Ty2>(_Val2));
}

namespace _CXX20_DEPRECATE_REL_OPS rel_ops {
    template <class _Ty>
    _CXX20_DEPRECATE_REL_OPS _NODISCARD bool operator!=(const _Ty& _Left, const _Ty& _Right) {
        return !(_Left == _Right);
    }

    template <class _Ty>
    _CXX20_DEPRECATE_REL_OPS _NODISCARD bool operator>(const _Ty& _Left, const _Ty& _Right) {
        return _Right < _Left;
    }

    template <class _Ty>
    _CXX20_DEPRECATE_REL_OPS _NODISCARD bool operator<=(const _Ty& _Left, const _Ty& _Right) {
        return !(_Right < _Left);
    }

    template <class _Ty>
    _CXX20_DEPRECATE_REL_OPS _NODISCARD bool operator>=(const _Ty& _Left, const _Ty& _Right) {
        return !(_Left < _Right);
    }
} // namespace rel_ops

// STRUCTS FOR STRUCTURED BINDINGS tuple_size AND tuple_element
template <class _Tuple>
struct tuple_size;

template <class _Tuple, class = void>
struct _Tuple_size_sfinae { // selected when tuple_size<_Tuple>::value isn't well-formed
};

template <class _Tuple>
struct _Tuple_size_sfinae<_Tuple, void_t<decltype(tuple_size<_Tuple>::value)>>
    : integral_constant<size_t, tuple_size<_Tuple>::value> { // selected when tuple_size<_Tuple>::value is well-formed
};

template <class _Tuple>
struct tuple_size<const _Tuple> : _Tuple_size_sfinae<_Tuple> { // size of const tuple
};

template <class _Tuple>
struct tuple_size<volatile _Tuple> : _Tuple_size_sfinae<_Tuple> { // size of volatile tuple
};

template <class _Tuple>
struct tuple_size<const volatile _Tuple> : _Tuple_size_sfinae<_Tuple> { // size of const volatile tuple
};

template <class _Ty>
_INLINE_VAR constexpr size_t tuple_size_v = tuple_size<_Ty>::value;

template <size_t _Index, class _Tuple>
struct tuple_element;

template <size_t _Index, class _Tuple>
struct _MSVC_KNOWN_SEMANTICS tuple_element<_Index, const _Tuple> : tuple_element<_Index, _Tuple> {
    using _Mybase = tuple_element<_Index, _Tuple>;
    using type    = add_const_t<typename _Mybase::type>;
};

template <size_t _Index, class _Tuple>
struct _MSVC_KNOWN_SEMANTICS tuple_element<_Index, volatile _Tuple> : tuple_element<_Index, _Tuple> {
    using _Mybase = tuple_element<_Index, _Tuple>;
    using type    = add_volatile_t<typename _Mybase::type>;
};

template <size_t _Index, class _Tuple>
struct _MSVC_KNOWN_SEMANTICS tuple_element<_Index, const volatile _Tuple> : tuple_element<_Index, _Tuple> {
    using _Mybase = tuple_element<_Index, _Tuple>;
    using type    = add_cv_t<typename _Mybase::type>;
};

template <size_t _Index, class _Tuple>
using tuple_element_t = typename tuple_element<_Index, _Tuple>::type;

// TUPLE INTERFACE TO array
template <class _Ty, size_t _Size>
class array;

template <class _Ty, size_t _Size>
struct tuple_size<array<_Ty, _Size>>
    : integral_constant<size_t, _Size> { // struct to determine number of elements in array
};

template <size_t _Idx, class _Ty, size_t _Size>
struct _MSVC_KNOWN_SEMANTICS tuple_element<_Idx, array<_Ty, _Size>> {
    static_assert(_Idx < _Size, "array index out of bounds");

    using type = _Ty;
};


// TUPLE INTERFACE TO tuple
template <class... _Types>
struct tuple_size<tuple<_Types...>> : integral_constant<size_t, sizeof...(_Types)> { // size of tuple
};

template <size_t _Index>
struct _MSVC_KNOWN_SEMANTICS tuple_element<_Index, tuple<>> { // enforce bounds checking
    static_assert(_Always_false<integral_constant<size_t, _Index>>, "tuple index out of bounds");
};

template <class _This, class... _Rest>
struct _MSVC_KNOWN_SEMANTICS tuple_element<0, tuple<_This, _Rest...>> { // select first element
    using type = _This;
    // MSVC assumes the meaning of _Ttype; remove or rename, but do not change semantics
    using _Ttype = tuple<_This, _Rest...>;
};

template <size_t _Index, class _This, class... _Rest>
struct _MSVC_KNOWN_SEMANTICS tuple_element<_Index, tuple<_This, _Rest...>>
    : tuple_element<_Index - 1, tuple<_Rest...>> { // recursive tuple_element definition
};

// TUPLE INTERFACE TO pair
template <class _Ty1, class _Ty2>
struct tuple_size<pair<_Ty1, _Ty2>> : integral_constant<size_t, 2> { // size of pair
};

template <size_t _Idx, class _Ty1, class _Ty2>
struct _MSVC_KNOWN_SEMANTICS tuple_element<_Idx, pair<_Ty1, _Ty2>> {
    static_assert(_Idx < 2, "pair index out of bounds");

    using type = conditional_t<_Idx == 0, _Ty1, _Ty2>;
};

template <class _Ret, class _Pair>
constexpr _Ret _Pair_get(_Pair& _Pr, integral_constant<size_t, 0>) noexcept { // get reference to element 0 in pair _Pr
    return _Pr.first;
}

template <class _Ret, class _Pair>
constexpr _Ret _Pair_get(_Pair& _Pr, integral_constant<size_t, 1>) noexcept { // get reference to element 1 in pair _Pr
    return _Pr.second;
}

template <size_t _Idx, class _Ty1, class _Ty2>
_NODISCARD constexpr tuple_element_t<_Idx, pair<_Ty1, _Ty2>>& get(
    pair<_Ty1, _Ty2>& _Pr) noexcept { // get reference to element at _Idx in pair _Pr
    using _Rtype = tuple_element_t<_Idx, pair<_Ty1, _Ty2>>&;
    return _Pair_get<_Rtype>(_Pr, integral_constant<size_t, _Idx>());
}

template <class _Ty1, class _Ty2>
_NODISCARD constexpr _Ty1& get(pair<_Ty1, _Ty2>& _Pr) noexcept { // get reference to element _Ty1 in pair _Pr
    return _STD get<0>(_Pr);
}

template <class _Ty2, class _Ty1>
_NODISCARD constexpr _Ty2& get(pair<_Ty1, _Ty2>& _Pr) noexcept { // get reference to element _Ty2 in pair _Pr
    return _STD get<1>(_Pr);
}

template <size_t _Idx, class _Ty1, class _Ty2>
_NODISCARD constexpr const tuple_element_t<_Idx, pair<_Ty1, _Ty2>>& get(
    const pair<_Ty1, _Ty2>& _Pr) noexcept { // get const reference to element at _Idx in pair _Pr
    using _Ctype = const tuple_element_t<_Idx, pair<_Ty1, _Ty2>>&;
    return _Pair_get<_Ctype>(_Pr, integral_constant<size_t, _Idx>());
}

template <class _Ty1, class _Ty2>
_NODISCARD constexpr const _Ty1& get(
    const pair<_Ty1, _Ty2>& _Pr) noexcept { // get const reference to element _Ty1 in pair _Pr
    return _STD get<0>(_Pr);
}

template <class _Ty2, class _Ty1>
_NODISCARD constexpr const _Ty2& get(
    const pair<_Ty1, _Ty2>& _Pr) noexcept { // get const reference to element _Ty2 in pair _Pr
    return _STD get<1>(_Pr);
}

template <size_t _Idx, class _Ty1, class _Ty2>
_NODISCARD constexpr tuple_element_t<_Idx, pair<_Ty1, _Ty2>>&& get(
    pair<_Ty1, _Ty2>&& _Pr) noexcept { // get rvalue reference to element at _Idx in pair _Pr
    using _RRtype = tuple_element_t<_Idx, pair<_Ty1, _Ty2>>&&;
    return _STD forward<_RRtype>(_STD get<_Idx>(_Pr));
}

template <class _Ty1, class _Ty2>
_NODISCARD constexpr _Ty1&& get(pair<_Ty1, _Ty2>&& _Pr) noexcept { // get rvalue reference to element _Ty1 in pair _Pr
    return _STD get<0>(_STD move(_Pr));
}

template <class _Ty2, class _Ty1>
_NODISCARD constexpr _Ty2&& get(pair<_Ty1, _Ty2>&& _Pr) noexcept { // get rvalue reference to element _Ty2 in pair _Pr
    return _STD get<1>(_STD move(_Pr));
}

template <size_t _Idx, class _Ty1, class _Ty2>
_NODISCARD constexpr const tuple_element_t<_Idx, pair<_Ty1, _Ty2>>&& get(
    const pair<_Ty1, _Ty2>&& _Pr) noexcept { // get const rvalue reference to element at _Idx in pair _Pr
    using _RRtype = const tuple_element_t<_Idx, pair<_Ty1, _Ty2>>&&;
    return _STD forward<_RRtype>(_STD get<_Idx>(_Pr));
}

template <class _Ty1, class _Ty2>
_NODISCARD constexpr const _Ty1&& get(
    const pair<_Ty1, _Ty2>&& _Pr) noexcept { // get const rvalue reference to element _Ty1 in pair _Pr
    return _STD get<0>(_STD move(_Pr));
}

template <class _Ty2, class _Ty1>
_NODISCARD constexpr const _Ty2&& get(
    const pair<_Ty1, _Ty2>&& _Pr) noexcept { // get const rvalue reference to element _Ty2 in pair _Pr
    return _STD get<1>(_STD move(_Pr));
}

// FUNCTION TEMPLATE exchange
template <class _Ty, class _Other = _Ty>
_CONSTEXPR20 _Ty exchange(_Ty& _Val, _Other&& _New_val) noexcept(
    conjunction_v<is_nothrow_move_constructible<_Ty>, is_nothrow_assignable<_Ty&, _Other>>) /* strengthened */ {
    // assign _New_val to _Val, return previous _Val
    _Ty _Old_val = static_cast<_Ty&&>(_Val);
    _Val         = static_cast<_Other&&>(_New_val);
    return _Old_val;
}

// FUNCTION TEMPLATE as_const
template <class _Ty>
_NODISCARD constexpr add_const_t<_Ty>& as_const(_Ty& _Val) noexcept { // view _Val through const lenses
    return _Val;
}

template <class _Ty>
void as_const(const _Ty&&) = delete;

#if _HAS_CXX17
// in_place TAG TYPE TEMPLATES
struct in_place_t { // tag used to select a constructor which initializes a contained object in place
    explicit in_place_t() = default;
};
inline constexpr in_place_t in_place{};

template <class>
struct in_place_type_t { // tag that selects a type to construct in place
    explicit in_place_type_t() = default;
};
template <class _Ty>
inline constexpr in_place_type_t<_Ty> in_place_type{};

template <size_t>
struct in_place_index_t { // tag that selects the index of a type to construct in place
    explicit in_place_index_t() = default;
};
template <size_t _Idx>
inline constexpr in_place_index_t<_Idx> in_place_index{};
#endif // _HAS_CXX17

#if _HAS_TR1_NAMESPACE
namespace _DEPRECATE_TR1_NAMESPACE tr1 {
    using _STD get;
    using _STD tuple_element;
    using _STD tuple_size;
} // namespace tr1
#endif // _HAS_TR1_NAMESPACE

_STD_END

#pragma pop_macro("new")
_STL_RESTORE_CLANG_WARNINGS
#pragma warning(pop)
#pragma pack(pop)
#endif // _STL_COMPILER_PREPROCESSOR
#endif // _UTILITY_