memory

// memory standard header

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

#pragma once
#ifndef _MEMORY_
#define _MEMORY_
#include <yvals_core.h>
#if _STL_COMPILER_PREPROCESSOR
#include <exception>
#include <iosfwd>
#include <type_traits>
#include <typeinfo>
#include <xmemory>

#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 uninitialized_copy_n
#if _HAS_IF_CONSTEXPR
template <class _InIt, class _Diff, class _NoThrowFwdIt>
_NoThrowFwdIt uninitialized_copy_n(const _InIt _First, const _Diff _Count_raw, _NoThrowFwdIt _Dest) {
    // copy [_First, _First + _Count) to [_Dest, ...)
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        auto _UFirst = _Get_unwrapped_n(_First, _Count);
        auto _UDest  = _Get_unwrapped_n(_Dest, _Count);
        if constexpr (_Ptr_copy_cat<decltype(_UFirst), decltype(_UDest)>::_Really_trivial) {
            _UDest = _Copy_memmove(_UFirst, _UFirst + _Count, _UDest);
        } else {
            _Uninitialized_backout<decltype(_UDest)> _Backout{_UDest};
            for (; 0 < _Count; --_Count, (void) ++_UFirst) {
                _Backout._Emplace_back(*_UFirst);
            }

            _UDest = _Backout._Release();
        }

        _Seek_wrapped(_Dest, _UDest);
    }

    return _Dest;
}
#else // ^^^ _HAS_IF_CONSTEXPR / !_HAS_IF_CONSTEXPR vvv
template <class _InIt, class _Diff, class _NoThrowFwdIt>
_NoThrowFwdIt _Uninitialized_copy_n_unchecked2(_InIt _First, _Diff _Count, const _NoThrowFwdIt _Dest,
    false_type) { // copy [_First, _First + _Count) to [_Dest, ...), no special optimization
    _Uninitialized_backout<_NoThrowFwdIt> _Backout{_Dest};
    for (; 0 < _Count; --_Count, (void) ++_First) {
        _Backout._Emplace_back(*_First);
    }

    return _Backout._Release();
}

template <class _InIt, class _Diff, class _NoThrowFwdIt>
_NoThrowFwdIt _Uninitialized_copy_n_unchecked2(const _InIt _First, const _Diff _Count, const _NoThrowFwdIt _Dest,
    true_type) { // copy [_First, _First + _Count) to [_Dest, ...), memmove optimization
    return _Copy_memmove(_First, _First + _Count, _Dest);
}

template <class _InIt, class _Diff, class _NoThrowFwdIt>
_NoThrowFwdIt uninitialized_copy_n(const _InIt _First, const _Diff _Count_raw, _NoThrowFwdIt _Dest) {
    // copy [_First, _First + _Count) to [_Dest, ...)]
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        auto _UFirst = _Get_unwrapped_n(_First, _Count);
        auto _UDest  = _Get_unwrapped_n(_Dest, _Count);
        _Seek_wrapped(_Dest, _Uninitialized_copy_n_unchecked2(_UFirst, _Count, _UDest,
                                 bool_constant<_Ptr_copy_cat<decltype(_UFirst), decltype(_UDest)>::_Really_trivial>{}));
    }

    return _Dest;
}
#endif // _HAS_IF_CONSTEXPR

#if _ITERATOR_DEBUG_ARRAY_OVERLOADS
template <class _InTy, size_t _InSize, class _Diff, class _NoThrowFwdIt>
_NoThrowFwdIt uninitialized_copy_n(_InTy (&_First)[_InSize], const _Diff _Count_raw, _NoThrowFwdIt _Dest) {
    // copy [_First, _First + _Count) to [_Dest, ...), array input
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        _STL_VERIFY_ARRAY_SIZE(_First, _Count);
        return _STD uninitialized_copy_n(static_cast<_InTy*>(_First), _Count, _Dest);
    }

    return _Dest;
}

template <class _InIt, class _Diff, class _OutTy, size_t _OutSize>
_OutTy* uninitialized_copy_n(const _InIt _First, const _Diff _Count_raw, _OutTy (&_Dest)[_OutSize]) {
    // copy [_First, _First + _Count) to [_Dest, ...), array dest
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        _STL_VERIFY_ARRAY_SIZE(_Dest, _Count);
        return _STD uninitialized_copy_n(_Get_unwrapped_n(_First, _Count), _Count, static_cast<_OutTy*>(_Dest));
    }

    return _Dest;
}

template <class _InTy, size_t _InSize, class _Diff, class _OutTy, size_t _OutSize>
_OutTy* uninitialized_copy_n(_InTy (&_First)[_InSize], const _Diff _Count_raw, _OutTy (&_Dest)[_OutSize]) {
    // copy [_First, _First + _Count) to [_Dest, ...), array input/dest
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        _STL_VERIFY_ARRAY_SIZE(_First, _Count);
        _STL_VERIFY_ARRAY_SIZE(_Dest, _Count);
        return _STD uninitialized_copy_n(static_cast<_InTy*>(_First), _Count, static_cast<_OutTy*>(_Dest));
    }

    return _Dest;
}
#endif // _ITERATOR_DEBUG_ARRAY_OVERLOADS

#if _HAS_CXX17
// FUNCTION TEMPLATE uninitialized_move
template <class _InIt, class _NoThrowFwdIt>
_NoThrowFwdIt uninitialized_move(const _InIt _First, const _InIt _Last, _NoThrowFwdIt _Dest) {
    // move [_First, _Last) to raw [_Dest, ...)
    _Adl_verify_range(_First, _Last);
    const auto _UFirst = _Get_unwrapped(_First);
    const auto _ULast  = _Get_unwrapped(_Last);
    const auto _UDest  = _Get_unwrapped_n(_Dest, _Idl_distance<_InIt>(_UFirst, _ULast));
    _Seek_wrapped(_Dest, _Uninitialized_move_unchecked(_UFirst, _ULast, _UDest));
    return _Dest;
}

#if _ITERATOR_DEBUG_ARRAY_OVERLOADS
template <class _InIt, class _OutTy, size_t _OutSize>
_OutTy* uninitialized_move(const _InIt _First, const _InIt _Last, _OutTy (&_Dest)[_OutSize]) {
    // move [_First, _Last) to raw [_Dest, ...)
    return _STD uninitialized_move(_First, _Last, _Array_iterator<_OutTy, _OutSize>(_Dest))._Unwrapped();
}
#endif // _ITERATOR_DEBUG_ARRAY_OVERLOADS

// FUNCTION TEMPLATE uninitialized_move_n
#if _HAS_IF_CONSTEXPR
template <class _InIt, class _Diff, class _NoThrowFwdIt>
pair<_InIt, _NoThrowFwdIt> uninitialized_move_n(_InIt _First, const _Diff _Count_raw, _NoThrowFwdIt _Dest) {
    // move [_First, _First + _Count) to [_Dest, ...)
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        auto _UFirst = _Get_unwrapped_n(_First, _Count);
        auto _UDest  = _Get_unwrapped_n(_Dest, _Count);
        if constexpr (_Ptr_move_cat<decltype(_UFirst), decltype(_UDest)>::_Really_trivial) {
            _UDest = _Copy_memmove(_UFirst, _UFirst + _Count, _UDest);
            _UFirst += _Count;
        } else {
            _Uninitialized_backout<decltype(_UDest)> _Backout{_UDest};
            for (; 0 < _Count; --_Count, (void) ++_UFirst) {
                _Backout._Emplace_back(_STD move(*_UFirst));
            }

            _UDest = _Backout._Release();
        }

        _Seek_wrapped(_Dest, _UDest);
        _Seek_wrapped(_First, _UFirst);
    }

    return {_First, _Dest};
}
#else // ^^^ _HAS_IF_CONSTEXPR / !_HAS_IF_CONSTEXPR vvv
template <class _InIt, class _Diff, class _NoThrowFwdIt>
pair<_InIt, _NoThrowFwdIt> _Uninitialized_move_n_unchecked1(_InIt _First, _Diff _Count, const _NoThrowFwdIt _Dest,
    false_type) { // move [_First, _First + _Count) to [_Dest, ...), no special optimization
    _Uninitialized_backout<_NoThrowFwdIt> _Backout{_Dest};
    for (; 0 < _Count; --_Count, (void) ++_First) {
        _Backout._Emplace_back(_STD move(*_First));
    }

    return pair<_InIt, _NoThrowFwdIt>(_First, _Backout._Release());
}

template <class _InIt, class _Diff, class _NoThrowFwdIt>
pair<_InIt, _NoThrowFwdIt> _Uninitialized_move_n_unchecked1(_InIt _First, _Diff _Count, _NoThrowFwdIt _Dest,
    true_type) { // move [_First, _First + _Count) to [_Dest, ...), memmove optimization
    if (0 < _Count) {
        _Dest = _Copy_memmove(_First, _First + _Count, _Dest);
        _First += _Count;
    }

    return pair<_InIt, _NoThrowFwdIt>(_First, _Dest);
}

template <class _InIt, class _Diff, class _NoThrowFwdIt>
pair<_InIt, _NoThrowFwdIt> uninitialized_move_n(_InIt _First, const _Diff _Count_raw, _NoThrowFwdIt _Dest) {
    // move [_First, _First + _Count) to [_Dest, ...)
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        auto _UFirst       = _Get_unwrapped_n(_First, _Count);
        auto _UDest        = _Get_unwrapped_n(_Dest, _Count);
        const auto _Result = _Uninitialized_move_n_unchecked1(_UFirst, _Count, _UDest,
            bool_constant<_Ptr_move_cat<decltype(_UFirst), decltype(_UDest)>::_Really_trivial>{});
        _Seek_wrapped(_Dest, _Result.second);
        _Seek_wrapped(_First, _Result.first);
    }

    return {_First, _Dest};
}
#endif // _HAS_IF_CONSTEXPR

#if _ITERATOR_DEBUG_ARRAY_OVERLOADS
template <class _InTy, size_t _InSize, class _Diff, class _NoThrowFwdIt>
pair<_InTy*, _NoThrowFwdIt> uninitialized_move_n(_InTy (&_First)[_InSize], const _Diff _Count_raw,
    _NoThrowFwdIt _Dest) { // move [_First, _First + _Count) to [_Dest, ...), array input
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        _STL_VERIFY_ARRAY_SIZE(_First, _Count);
        return _STD uninitialized_move_n(static_cast<_InTy*>(_First), _Count, _Dest);
    }

    return {_First, _Dest};
}

template <class _InIt, class _Diff, class _OutTy, size_t _OutSize>
pair<_InIt, _OutTy*> uninitialized_move_n(_InIt _First, const _Diff _Count_raw, _OutTy (&_Dest)[_OutSize]) {
    // move [_First, _First + _Count) to [_Dest, ...), array dest
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        _STL_VERIFY_ARRAY_SIZE(_Dest, _Count);
        return _STD uninitialized_move_n(_First, _Count, static_cast<_OutTy*>(_Dest));
    }

    return {_First, _Dest};
}

template <class _InTy, size_t _InSize, class _Diff, class _OutTy, size_t _OutSize>
pair<_InTy*, _OutTy*> uninitialized_move_n(_InTy (&_First)[_InSize], const _Diff _Count_raw,
    _OutTy (&_Dest)[_OutSize]) { // move [_First, _First + _Count) to [_Dest, ...), array input/dest
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        _STL_VERIFY_ARRAY_SIZE(_First, _Count);
        _STL_VERIFY_ARRAY_SIZE(_Dest, _Count);
        return _STD uninitialized_move_n(static_cast<_InTy*>(_First), _Count, static_cast<_OutTy*>(_Dest));
    }

    return {_First, _Dest};
}
#endif // _ITERATOR_DEBUG_ARRAY_OVERLOADS

#endif // _HAS_CXX17

// FUNCTION TEMPLATE uninitialized_fill_n
#if _HAS_IF_CONSTEXPR
template <class _NoThrowFwdIt, class _Diff, class _Tval>
_NoThrowFwdIt uninitialized_fill_n(_NoThrowFwdIt _First, const _Diff _Count_raw, const _Tval& _Val) {
    // copy _Count copies of _Val to raw _First
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        auto _UFirst = _Get_unwrapped_n(_First, _Count);
        if constexpr (_Fill_memset_is_safe<_Unwrapped_n_t<_NoThrowFwdIt>, _Tval>) {
            _CSTD memset(_UFirst, static_cast<unsigned char>(_Val), _Count);
            _UFirst += _Count;
        } else {
            _Uninitialized_backout<_Unwrapped_n_t<_NoThrowFwdIt>> _Backout{_UFirst};
            for (; 0 < _Count; --_Count) {
                _Backout._Emplace_back(_Val);
            }

            _UFirst = _Backout._Release();
        }

        _Seek_wrapped(_First, _UFirst);
    }

    return _First;
}
#else // ^^^ _HAS_IF_CONSTEXPR // !_HAS_IF_CONSTEXPR vvv
template <class _NoThrowFwdIt, class _Diff, class _Tval>
_NoThrowFwdIt _Uninitialized_fill_n_unchecked1(
    const _NoThrowFwdIt _First, _Diff _Count, const _Tval& _Val, false_type) {
    // copy _Count copies of _Val to raw _First, no special optimization
    _Uninitialized_backout<_NoThrowFwdIt> _Backout{_First};
    for (; 0 < _Count; --_Count) {
        _Backout._Emplace_back(_Val);
    }

    return _Backout._Release();
}

template <class _NoThrowFwdIt, class _Diff, class _Tval>
_NoThrowFwdIt _Uninitialized_fill_n_unchecked1(
    const _NoThrowFwdIt _First, const _Diff _Count, const _Tval& _Val, true_type) {
    // copy _Count copies of _Val to raw _First, memset optimization
    _CSTD memset(_First, static_cast<unsigned char>(_Val), _Count);
    return _First + _Count;
}

template <class _NoThrowFwdIt, class _Diff, class _Tval>
_NoThrowFwdIt uninitialized_fill_n(_NoThrowFwdIt _First, const _Diff _Count_raw, const _Tval& _Val) {
    // copy _Count copies of _Val to raw _First
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        const auto _UFirst = _Get_unwrapped_n(_First, _Count);
        _Seek_wrapped(_First, _Uninitialized_fill_n_unchecked1(_UFirst, _Count, _Val,
                                  bool_constant<_Fill_memset_is_safe<_Unwrapped_t<_NoThrowFwdIt>, _Tval>>{}));
    }

    return _First;
}
#endif // _HAS_IF_CONSTEXPR

#if _HAS_CXX17
// FUNCTION TEMPLATE destroy_at
template <class _Ty>
void destroy_at(_Ty* const _Location) { // destroy _Ty at memory address _Location
    _Location->~_Ty();
}

// FUNCTION TEMPLATE destroy
template <class _NoThrowFwdIt>
void destroy(const _NoThrowFwdIt _First, const _NoThrowFwdIt _Last) { // destroy all elements in [_First, _Last)
    _Adl_verify_range(_First, _Last);
    _Destroy_range(_Get_unwrapped(_First), _Get_unwrapped(_Last));
}

// FUNCTION TEMPLATE destroy_n
template <class _NoThrowFwdIt, class _Diff>
_NoThrowFwdIt destroy_n(_NoThrowFwdIt _First, const _Diff _Count_raw) {
    // destroy all elements in [_First, _First + _Count)
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        auto _UFirst = _Get_unwrapped_n(_First, _Count);
        if constexpr (is_trivially_destructible_v<_Iter_value_t<_NoThrowFwdIt>>) {
            _STD advance(_UFirst, _Count);
        } else {
            do {
                _Destroy_in_place(*_UFirst);
                ++_UFirst;
                --_Count;
            } while (0 < _Count);
        }

        _Seek_wrapped(_First, _UFirst);
    }

    return _First;
}

// FUNCTION TEMPLATE uninitialized_default_construct
template <class _NoThrowFwdIt>
void uninitialized_default_construct(const _NoThrowFwdIt _First, const _NoThrowFwdIt _Last) {
    // default-initialize all elements in [_First, _Last)
    using _Ty = _Iter_value_t<_NoThrowFwdIt>;
    _Adl_verify_range(_First, _Last);
    if constexpr (!is_trivially_default_constructible_v<_Ty>) {
        const auto _ULast = _Get_unwrapped(_Last);
        _Uninitialized_backout _Backout{_Get_unwrapped(_First)};
        for (; _Backout._Last != _ULast; ++_Backout._Last) {
            ::new (static_cast<void*>(_Unfancy(_Backout._Last))) _Ty;
        }

        _Backout._Release();
    }
}

// FUNCTION TEMPLATE uninitialized_default_construct_n
template <class _NoThrowFwdIt, class _Diff>
_NoThrowFwdIt uninitialized_default_construct_n(_NoThrowFwdIt _First, const _Diff _Count_raw) {
    // default-initialize all elements in [_First, _First + _Count_raw)
    using _Ty                      = _Iter_value_t<_NoThrowFwdIt>;
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        if constexpr (is_trivially_default_constructible_v<_Ty>) {
            _STD advance(_First, _Count);
        } else {
            _Uninitialized_backout _Backout{_Get_unwrapped_n(_First, _Count)};
            for (; 0 < _Count; ++_Backout._Last, (void) --_Count) {
                ::new (static_cast<void*>(_Unfancy(_Backout._Last))) _Ty;
            }

            _Seek_wrapped(_First, _Backout._Release());
        }
    }

    return _First;
}

// FUNCTION TEMPLATE uninitialized_value_construct
template <class _NoThrowFwdIt>
void uninitialized_value_construct(const _NoThrowFwdIt _First, const _NoThrowFwdIt _Last) {
    // value-initialize all elements in [_First, _Last)
    _Adl_verify_range(_First, _Last);
    const auto _UFirst = _Get_unwrapped(_First);
    const auto _ULast  = _Get_unwrapped(_Last);
    if constexpr (_Use_memset_value_construct_v<_Unwrapped_t<_NoThrowFwdIt>>) {
        _Zero_range(_UFirst, _ULast);
    } else {
        _Uninitialized_backout _Backout{_UFirst};
        while (_Backout._Last != _ULast) {
            _Backout._Emplace_back();
        }

        _Backout._Release();
    }
}

// FUNCTION TEMPLATE uninitialized_value_construct_n
template <class _NoThrowFwdIt, class _Diff>
_NoThrowFwdIt uninitialized_value_construct_n(_NoThrowFwdIt _First, const _Diff _Count_raw) {
    // value-initialize all elements in [_First, _First + _Count_raw)
    _Algorithm_int_t<_Diff> _Count = _Count_raw;
    if (0 < _Count) {
        _Seek_wrapped(_First, _Uninitialized_value_construct_n_unchecked1(_Get_unwrapped_n(_First, _Count), _Count));
    }

    return _First;
}

#endif // _HAS_CXX17


// CLASS TEMPLATE raw_storage_iterator
template <class _OutIt, class _Ty>
class _CXX17_DEPRECATE_RAW_STORAGE_ITERATOR raw_storage_iterator { // wrap stores to raw buffer as output iterator
public:
    using iterator_category = output_iterator_tag;
    using value_type        = void;
    using difference_type   = void;
    using pointer           = void;
    using reference         = void;

    explicit raw_storage_iterator(_OutIt _First) : _Next(_First) {}

    _NODISCARD raw_storage_iterator& operator*() { // pretend to return designated value
        return *this;
    }

    raw_storage_iterator& operator=(const _Ty& _Val) { // construct value designated by stored iterator
        _Construct_in_place(*_Next, _Val);
        return *this;
    }

    raw_storage_iterator& operator=(_Ty&& _Val) { // construct value designated by stored iterator
        _Construct_in_place(*_Next, _STD move(_Val));
        return *this;
    }

    raw_storage_iterator& operator++() {
        ++_Next;
        return *this;
    }

    raw_storage_iterator operator++(int) {
        raw_storage_iterator _Ans = *this;
        ++_Next;
        return _Ans;
    }

    _NODISCARD _OutIt base() const {
        return _Next;
    }

private:
    _OutIt _Next;
};


#if _HAS_AUTO_PTR_ETC
// CLASS TEMPLATE auto_ptr
template <class _Ty>
class auto_ptr;

template <class _Ty>
struct auto_ptr_ref { // proxy reference for auto_ptr copying
    explicit auto_ptr_ref(_Ty* _Right) : _Ref(_Right) {}

    _Ty* _Ref; // generic pointer to auto_ptr ptr
};

template <class _Ty>
class auto_ptr { // wrap an object pointer to ensure destruction
public:
    using element_type = _Ty;

    explicit auto_ptr(_Ty* _Ptr = nullptr) noexcept : _Myptr(_Ptr) {}

    auto_ptr(auto_ptr& _Right) noexcept : _Myptr(_Right.release()) {}

    auto_ptr(auto_ptr_ref<_Ty> _Right) noexcept {
        _Ty* _Ptr   = _Right._Ref;
        _Right._Ref = nullptr; // release old
        _Myptr      = _Ptr; // reset this
    }

    template <class _Other>
    operator auto_ptr<_Other>() noexcept { // convert to compatible auto_ptr
        return auto_ptr<_Other>(*this);
    }

    template <class _Other>
    operator auto_ptr_ref<_Other>() noexcept { // convert to compatible auto_ptr_ref
        _Other* _Cvtptr = _Myptr; // test implicit conversion
        auto_ptr_ref<_Other> _Ans(_Cvtptr);
        _Myptr = nullptr; // pass ownership to auto_ptr_ref
        return _Ans;
    }

    template <class _Other>
    auto_ptr& operator=(auto_ptr<_Other>& _Right) noexcept {
        reset(_Right.release());
        return *this;
    }

    template <class _Other>
    auto_ptr(auto_ptr<_Other>& _Right) noexcept : _Myptr(_Right.release()) {}

    auto_ptr& operator=(auto_ptr& _Right) noexcept {
        reset(_Right.release());
        return *this;
    }

    auto_ptr& operator=(auto_ptr_ref<_Ty> _Right) noexcept {
        _Ty* _Ptr   = _Right._Ref;
        _Right._Ref = 0; // release old
        reset(_Ptr); // set new
        return *this;
    }

    ~auto_ptr() noexcept {
        delete _Myptr;
    }

    _NODISCARD _Ty& operator*() const noexcept {
#if _ITERATOR_DEBUG_LEVEL == 2
        _STL_VERIFY(_Myptr, "auto_ptr not dereferenceable");
#endif // _ITERATOR_DEBUG_LEVEL == 2

        return *get();
    }

    _NODISCARD _Ty* operator->() const noexcept {
#if _ITERATOR_DEBUG_LEVEL == 2
        _STL_VERIFY(_Myptr, "auto_ptr not dereferenceable");
#endif // _ITERATOR_DEBUG_LEVEL == 2

        return get();
    }

    _NODISCARD _Ty* get() const noexcept {
        return _Myptr;
    }

    _Ty* release() noexcept {
        _Ty* _Tmp = _Myptr;
        _Myptr    = nullptr;
        return _Tmp;
    }

    void reset(_Ty* _Ptr = nullptr) noexcept { // destroy designated object and store new pointer
        if (_Ptr != _Myptr) {
            delete _Myptr;
        }

        _Myptr = _Ptr;
    }

private:
    _Ty* _Myptr; // the wrapped object pointer
};

template <>
class auto_ptr<void> {
public:
    using element_type = void;
};
#endif // _HAS_AUTO_PTR_ETC


// CLASS bad_weak_ptr
class bad_weak_ptr : public exception { // exception type for invalid use of expired weak_ptr object
public:
    bad_weak_ptr() noexcept {}

    _NODISCARD virtual const char* __CLR_OR_THIS_CALL what() const noexcept override {
        // return pointer to message string
        return "bad_weak_ptr";
    }
};

[[noreturn]] inline void _Throw_bad_weak_ptr() {
    _THROW(bad_weak_ptr{});
}

// CLASS _Ref_count_base
class __declspec(novtable) _Ref_count_base { // common code for reference counting
private:
#ifdef _M_CEE_PURE
    // permanent workaround to avoid mentioning _purecall in msvcurt.lib, ptrustu.lib, or other support libs
    virtual void _Destroy() noexcept {
        _STD terminate();
    }

    virtual void _Delete_this() noexcept {
        _STD terminate();
    }
#else // ^^^ _M_CEE_PURE / !_M_CEE_PURE vvv
    virtual void _Destroy() noexcept     = 0; // destroy managed resource
    virtual void _Delete_this() noexcept = 0; // destroy self
#endif // _M_CEE_PURE

    _Atomic_counter_t _Uses  = 1;
    _Atomic_counter_t _Weaks = 1;

protected:
    constexpr _Ref_count_base() noexcept = default; // non-atomic initializations

public:
    _Ref_count_base(const _Ref_count_base&) = delete;
    _Ref_count_base& operator=(const _Ref_count_base&) = delete;

    virtual ~_Ref_count_base() noexcept {} // TRANSITION, should be non-virtual

    bool _Incref_nz() noexcept { // increment use count if not zero, return true if successful
        auto& _Volatile_uses = reinterpret_cast<volatile long&>(_Uses);
        long _Count          = _ISO_VOLATILE_LOAD32(_Volatile_uses);

        while (_Count != 0) {
            const long _Old_value = _INTRIN_RELAXED(_InterlockedCompareExchange)(&_Volatile_uses, _Count + 1, _Count);
            if (_Old_value == _Count) {
                return true;
            }

            _Count = _Old_value;
        }

        return false;
    }

    void _Incref() noexcept { // increment use count
        _MT_INCR(_Uses);
    }

    void _Incwref() noexcept { // increment weak reference count
        _MT_INCR(_Weaks);
    }

    void _Decref() noexcept { // decrement use count
        if (_MT_DECR(_Uses) == 0) {
            _Destroy();
            _Decwref();
        }
    }

    void _Decwref() noexcept { // decrement weak reference count
        if (_MT_DECR(_Weaks) == 0) {
            _Delete_this();
        }
    }

    long _Use_count() const noexcept {
        return static_cast<long>(_Uses);
    }

    virtual void* _Get_deleter(const type_info&) const noexcept {
        return nullptr;
    }
};

// CLASS TEMPLATE _Ref_count
template <class _Ty>
class _Ref_count : public _Ref_count_base { // handle reference counting for pointer without deleter
public:
    explicit _Ref_count(_Ty* _Px) : _Ref_count_base(), _Ptr(_Px) {}

private:
    virtual void _Destroy() noexcept override { // destroy managed resource
        delete _Ptr;
    }

    virtual void _Delete_this() noexcept override { // destroy self
        delete this;
    }

    _Ty* _Ptr;
};

// CLASS TEMPLATE _Ref_count_resource
template <class _Resource, class _Dx>
class _Ref_count_resource : public _Ref_count_base { // handle reference counting for object with deleter
public:
    _Ref_count_resource(_Resource _Px, _Dx _Dt)
        : _Ref_count_base(), _Mypair(_One_then_variadic_args_t(), _STD move(_Dt), _Px) {}

    virtual void* _Get_deleter(const type_info& _Typeid) const noexcept override {
#if _HAS_STATIC_RTTI
        if (_Typeid == typeid(_Dx)) {
            return const_cast<_Dx*>(_STD addressof(_Mypair._Get_first()));
        }
#else // _HAS_STATIC_RTTI
        (void) _Typeid;
#endif // _HAS_STATIC_RTTI

        return nullptr;
    }

private:
    virtual void _Destroy() noexcept override { // destroy managed resource
        _Mypair._Get_first()(_Mypair._Myval2);
    }

    virtual void _Delete_this() noexcept override { // destroy self
        delete this;
    }

    _Compressed_pair<_Dx, _Resource> _Mypair;
};

// CLASS TEMPLATE _Ref_count_resource_alloc
template <class _Resource, class _Dx, class _Alloc>
class _Ref_count_resource_alloc : public _Ref_count_base {
    // handle reference counting for object with deleter and allocator
public:
    _Ref_count_resource_alloc(_Resource _Px, _Dx _Dt, const _Alloc& _Ax)
        : _Ref_count_base(),
          _Mypair(_One_then_variadic_args_t(), _STD move(_Dt), _One_then_variadic_args_t(), _Ax, _Px) {}

    virtual void* _Get_deleter(const type_info& _Typeid) const noexcept override {
#if _HAS_STATIC_RTTI
        if (_Typeid == typeid(_Dx)) {
            return const_cast<_Dx*>(_STD addressof(_Mypair._Get_first()));
        }
#else // _HAS_STATIC_RTTI
        (void) _Typeid;
#endif // _HAS_STATIC_RTTI

        return nullptr;
    }

private:
    using _Myalty = _Rebind_alloc_t<_Alloc, _Ref_count_resource_alloc>;

    virtual void _Destroy() noexcept override { // destroy managed resource
        _Mypair._Get_first()(_Mypair._Myval2._Myval2);
    }

    virtual void _Delete_this() noexcept override { // destroy self
        _Myalty _Al = _Mypair._Myval2._Get_first();
        this->~_Ref_count_resource_alloc();
        _Deallocate_plain(_Al, this);
    }

    _Compressed_pair<_Dx, _Compressed_pair<_Myalty, _Resource>> _Mypair;
};

// DECLARATIONS
template <class _Ty>
struct default_delete;

template <class _Ty, class _Dx = default_delete<_Ty>>
class unique_ptr;

template <class _Ty>
class shared_ptr;

template <class _Ty>
class weak_ptr;

template <class _Yty, class = void>
struct _Can_enable_shared : false_type {}; // detect unambiguous and accessible inheritance from enable_shared_from_this

template <class _Yty>
struct _Can_enable_shared<_Yty, void_t<typename _Yty::_Esft_type>>
    : is_convertible<remove_cv_t<_Yty>*, typename _Yty::_Esft_type*>::type {
    // is_convertible is necessary to verify unambiguous inheritance
};

#if !_HAS_IF_CONSTEXPR
template <class _Other, class _Yty>
void _Enable_shared_from_this1(const shared_ptr<_Other>& _This, _Yty* _Ptr, true_type) noexcept {
    // enable shared_from_this
    if (_Ptr && _Ptr->_Wptr.expired()) {
        _Ptr->_Wptr = shared_ptr<remove_cv_t<_Yty>>(_This, const_cast<remove_cv_t<_Yty>*>(_Ptr));
    }
}

template <class _Other, class _Yty>
void _Enable_shared_from_this1(const shared_ptr<_Other>&, _Yty*, false_type) noexcept {
    // don't enable shared_from_this
}
#endif // !_HAS_IF_CONSTEXPR

// CLASS TEMPLATE _Ptr_base
struct _Exception_ptr_access;

template <class _Ty>
class _Ptr_base { // base class for shared_ptr and weak_ptr
public:
    using element_type = remove_extent_t<_Ty>;

    _NODISCARD long use_count() const noexcept {
        return _Rep ? _Rep->_Use_count() : 0;
    }

    template <class _Ty2>
    _NODISCARD bool owner_before(const _Ptr_base<_Ty2>& _Right) const noexcept { // compare addresses of manager objects
        return _Rep < _Right._Rep;
    }

    _Ptr_base(const _Ptr_base&) = delete;
    _Ptr_base& operator=(const _Ptr_base&) = delete;

protected:
    _NODISCARD element_type* get() const noexcept {
        return _Ptr;
    }

    constexpr _Ptr_base() noexcept = default;

    ~_Ptr_base() = default;

    template <class _Ty2>
    void _Move_construct_from(_Ptr_base<_Ty2>&& _Right) noexcept {
        // implement shared_ptr's (converting) move ctor and weak_ptr's move ctor
        _Ptr = _Right._Ptr;
        _Rep = _Right._Rep;

        _Right._Ptr = nullptr;
        _Right._Rep = nullptr;
    }

    template <class _Ty2>
    void _Copy_construct_from(const shared_ptr<_Ty2>& _Other) noexcept {
        // implement shared_ptr's (converting) copy ctor
        if (_Other._Rep) {
            _Other._Rep->_Incref();
        }

        _Ptr = _Other._Ptr;
        _Rep = _Other._Rep;
    }

    template <class _Ty2>
    void _Alias_construct_from(const shared_ptr<_Ty2>& _Other, element_type* _Px) noexcept {
        // implement shared_ptr's aliasing ctor
        if (_Other._Rep) {
            _Other._Rep->_Incref();
        }

        _Ptr = _Px;
        _Rep = _Other._Rep;
    }

    template <class _Ty2>
    void _Alias_move_construct_from(shared_ptr<_Ty2>&& _Other, element_type* _Px) noexcept {
        // implement shared_ptr's aliasing move ctor
        _Ptr = _Px;
        _Rep = _Other._Rep;

        _Other._Ptr = nullptr;
        _Other._Rep = nullptr;
    }

    template <class _Ty0>
    friend class weak_ptr; // specifically, weak_ptr::lock()

    template <class _Ty2>
    bool _Construct_from_weak(const weak_ptr<_Ty2>& _Other) noexcept {
        // implement shared_ptr's ctor from weak_ptr, and weak_ptr::lock()
        if (_Other._Rep && _Other._Rep->_Incref_nz()) {
            _Ptr = _Other._Ptr;
            _Rep = _Other._Rep;
            return true;
        }

        return false;
    }

    void _Decref() noexcept { // decrement reference count
        if (_Rep) {
            _Rep->_Decref();
        }
    }

    void _Swap(_Ptr_base& _Right) noexcept { // swap pointers
        _STD swap(_Ptr, _Right._Ptr);
        _STD swap(_Rep, _Right._Rep);
    }

    template <class _Ty2>
    void _Weakly_construct_from(const _Ptr_base<_Ty2>& _Other) noexcept { // implement weak_ptr's ctors
        if (_Other._Rep) {
            _Ptr = _Other._Ptr;
            _Rep = _Other._Rep;
            _Rep->_Incwref();
        } else {
            _STL_INTERNAL_CHECK(!_Ptr && !_Rep);
        }
    }

    void _Decwref() noexcept { // decrement weak reference count
        if (_Rep) {
            _Rep->_Decwref();
        }
    }

private:
    element_type* _Ptr{nullptr};
    _Ref_count_base* _Rep{nullptr};

    template <class _Ty0>
    friend class _Ptr_base;

    friend shared_ptr<_Ty>;

    friend _Exception_ptr_access;

#if _HAS_STATIC_RTTI
    template <class _Dx, class _Ty0>
    friend _Dx* get_deleter(const shared_ptr<_Ty0>& _Sx) noexcept;
#endif // _HAS_STATIC_RTTI
};

// TYPE TRAIT _Can_scalar_delete
template <class _Yty, class = void>
struct _Can_scalar_delete : false_type {};
template <class _Yty>
struct _Can_scalar_delete<_Yty, void_t<decltype(delete _STD declval<_Yty*>())>> : true_type {};

// TYPE TRAIT _Can_array_delete
template <class _Yty, class = void>
struct _Can_array_delete : false_type {};
template <class _Yty>
struct _Can_array_delete<_Yty, void_t<decltype(delete[] _STD declval<_Yty*>())>> : true_type {};

// TYPE TRAIT _Can_call_function_object
template <class _Fx, class _Arg, class = void>
struct _Can_call_function_object : false_type {};
template <class _Fx, class _Arg>
struct _Can_call_function_object<_Fx, _Arg, void_t<decltype(_STD declval<_Fx>()(_STD declval<_Arg>()))>> : true_type {};

// TYPE TRAIT _SP_convertible
template <class _Yty, class _Ty>
struct _SP_convertible : is_convertible<_Yty*, _Ty*>::type {};
template <class _Yty, class _Uty>
struct _SP_convertible<_Yty, _Uty[]> : is_convertible<_Yty (*)[], _Uty (*)[]>::type {};
template <class _Yty, class _Uty, size_t _Ext>
struct _SP_convertible<_Yty, _Uty[_Ext]> : is_convertible<_Yty (*)[_Ext], _Uty (*)[_Ext]>::type {};

// TYPE TRAIT _SP_pointer_compatible
template <class _Yty, class _Ty>
struct _SP_pointer_compatible : is_convertible<_Yty*, _Ty*>::type {
    // N4659 [util.smartptr.shared]/5 "a pointer type Y* is said to be compatible
    // with a pointer type T* " "when either Y* is convertible to T* ..."
};
template <class _Uty, size_t _Ext>
struct _SP_pointer_compatible<_Uty[_Ext], _Uty[]> : true_type {
    // N4659 [util.smartptr.shared]/5 "... or Y is U[N] and T is cv U[]."
};
template <class _Uty, size_t _Ext>
struct _SP_pointer_compatible<_Uty[_Ext], const _Uty[]> : true_type {
    // N4659 [util.smartptr.shared]/5 "... or Y is U[N] and T is cv U[]."
};
template <class _Uty, size_t _Ext>
struct _SP_pointer_compatible<_Uty[_Ext], volatile _Uty[]> : true_type {
    // N4659 [util.smartptr.shared]/5 "... or Y is U[N] and T is cv U[]."
};
template <class _Uty, size_t _Ext>
struct _SP_pointer_compatible<_Uty[_Ext], const volatile _Uty[]> : true_type {
    // N4659 [util.smartptr.shared]/5 "... or Y is U[N] and T is cv U[]."
};

// CLASS TEMPLATE shared_ptr
template <class _Ux>
struct _Temporary_owner {
    _Ux* _Ptr;

    explicit _Temporary_owner(_Ux* const _Ptr_) noexcept : _Ptr(_Ptr_) {}
    _Temporary_owner(const _Temporary_owner&) = delete;
    _Temporary_owner& operator=(const _Temporary_owner&) = delete;
    ~_Temporary_owner() {
        delete _Ptr;
    }
};

template <class _UxptrOrNullptr, class _Dx>
struct _Temporary_owner_del {
    _UxptrOrNullptr _Ptr;
    _Dx& _Dt;
    bool _Call_deleter = true;

    explicit _Temporary_owner_del(const _UxptrOrNullptr _Ptr_, _Dx& _Dt_) noexcept : _Ptr(_Ptr_), _Dt(_Dt_) {}
    _Temporary_owner_del(const _Temporary_owner_del&) = delete;
    _Temporary_owner_del& operator=(const _Temporary_owner_del&) = delete;
    ~_Temporary_owner_del() {
        if (_Call_deleter) {
            _Dt(_Ptr);
        }
    }
};

template <class _Ty>
class shared_ptr : public _Ptr_base<_Ty> { // class for reference counted resource management
private:
    using _Mybase = _Ptr_base<_Ty>;

public:
    using typename _Mybase::element_type;

#if _HAS_CXX17
    using weak_type = weak_ptr<_Ty>;
#endif // _HAS_CXX17

    constexpr shared_ptr() noexcept {} // construct empty shared_ptr

    constexpr shared_ptr(nullptr_t) noexcept {} // construct empty shared_ptr

    template <class _Ux,
        enable_if_t<conjunction_v<conditional_t<is_array_v<_Ty>, _Can_array_delete<_Ux>, _Can_scalar_delete<_Ux>>,
                        _SP_convertible<_Ux, _Ty>>,
            int> = 0>
    explicit shared_ptr(_Ux* _Px) { // construct shared_ptr object that owns _Px
#if _HAS_IF_CONSTEXPR
        if constexpr (is_array_v<_Ty>) {
            _Setpd(_Px, default_delete<_Ux[]>{});
        } else {
            _Temporary_owner<_Ux> _Owner(_Px);
            _Set_ptr_rep_and_enable_shared(_Owner._Ptr, new _Ref_count<_Ux>(_Owner._Ptr));
            _Owner._Ptr = nullptr;
        }
#else // ^^^ _HAS_IF_CONSTEXPR // !_HAS_IF_CONSTEXPR vvv
        _Setp(_Px, is_array<_Ty>{});
#endif // _HAS_IF_CONSTEXPR
    }

    template <class _Ux, class _Dx,
        enable_if_t<conjunction_v<is_move_constructible<_Dx>, _Can_call_function_object<_Dx&, _Ux*&>,
                        _SP_convertible<_Ux, _Ty>>,
            int> = 0>
    shared_ptr(_Ux* _Px, _Dx _Dt) { // construct with _Px, deleter
        _Setpd(_Px, _STD move(_Dt));
    }

    template <class _Ux, class _Dx, class _Alloc,
        enable_if_t<conjunction_v<is_move_constructible<_Dx>, _Can_call_function_object<_Dx&, _Ux*&>,
                        _SP_convertible<_Ux, _Ty>>,
            int> = 0>
    shared_ptr(_Ux* _Px, _Dx _Dt, _Alloc _Ax) { // construct with _Px, deleter, allocator
        _Setpda(_Px, _STD move(_Dt), _Ax);
    }

    template <class _Dx,
        enable_if_t<conjunction_v<is_move_constructible<_Dx>, _Can_call_function_object<_Dx&, nullptr_t&>>, int> = 0>
    shared_ptr(nullptr_t, _Dx _Dt) { // construct with nullptr, deleter
        _Setpd(nullptr, _STD move(_Dt));
    }

    template <class _Dx, class _Alloc,
        enable_if_t<conjunction_v<is_move_constructible<_Dx>, _Can_call_function_object<_Dx&, nullptr_t&>>, int> = 0>
    shared_ptr(nullptr_t, _Dx _Dt, _Alloc _Ax) { // construct with nullptr, deleter, allocator
        _Setpda(nullptr, _STD move(_Dt), _Ax);
    }

    template <class _Ty2>
    shared_ptr(const shared_ptr<_Ty2>& _Right, element_type* _Px) noexcept {
        // construct shared_ptr object that aliases _Right
        this->_Alias_construct_from(_Right, _Px);
    }

    template <class _Ty2>
    shared_ptr(shared_ptr<_Ty2>&& _Right, element_type* _Px) noexcept {
        // move construct shared_ptr object that aliases _Right
        this->_Alias_move_construct_from(_STD move(_Right), _Px);
    }

    shared_ptr(const shared_ptr& _Other) noexcept { // construct shared_ptr object that owns same resource as _Other
        this->_Copy_construct_from(_Other);
    }

    template <class _Ty2, enable_if_t<_SP_pointer_compatible<_Ty2, _Ty>::value, int> = 0>
    shared_ptr(const shared_ptr<_Ty2>& _Other) noexcept {
        // construct shared_ptr object that owns same resource as _Other
        this->_Copy_construct_from(_Other);
    }

    shared_ptr(shared_ptr&& _Right) noexcept { // construct shared_ptr object that takes resource from _Right
        this->_Move_construct_from(_STD move(_Right));
    }

    template <class _Ty2, enable_if_t<_SP_pointer_compatible<_Ty2, _Ty>::value, int> = 0>
    shared_ptr(shared_ptr<_Ty2>&& _Right) noexcept { // construct shared_ptr object that takes resource from _Right
        this->_Move_construct_from(_STD move(_Right));
    }

    template <class _Ty2, enable_if_t<_SP_pointer_compatible<_Ty2, _Ty>::value, int> = 0>
    explicit shared_ptr(const weak_ptr<_Ty2>& _Other) { // construct shared_ptr object that owns resource *_Other
        if (!this->_Construct_from_weak(_Other)) {
            _Throw_bad_weak_ptr();
        }
    }

#if _HAS_AUTO_PTR_ETC
    template <class _Ty2, enable_if_t<is_convertible_v<_Ty2*, _Ty*>, int> = 0>
    shared_ptr(auto_ptr<_Ty2>&& _Other) { // construct shared_ptr object that owns *_Other.get()
        _Ty2* _Px = _Other.get();
        _Set_ptr_rep_and_enable_shared(_Px, new _Ref_count<_Ty2>(_Px));
        _Other.release();
    }
#endif // _HAS_AUTO_PTR_ETC

    template <class _Ux, class _Dx,
        enable_if_t<conjunction_v<_SP_pointer_compatible<_Ux, _Ty>,
                        is_convertible<typename unique_ptr<_Ux, _Dx>::pointer, element_type*>>,
            int> = 0>
    shared_ptr(unique_ptr<_Ux, _Dx>&& _Other) {
        using _Fancy_t   = typename unique_ptr<_Ux, _Dx>::pointer;
        using _Raw_t     = typename unique_ptr<_Ux, _Dx>::element_type*;
        using _Deleter_t = conditional_t<is_reference_v<_Dx>, decltype(_STD ref(_Other.get_deleter())), _Dx>;

        const _Fancy_t _Fancy = _Other.get();

        if (_Fancy) {
            const _Raw_t _Raw = _Fancy;
            const auto _Rx    = new _Ref_count_resource<_Fancy_t, _Deleter_t>(_Fancy, _Other.get_deleter());
            _Set_ptr_rep_and_enable_shared(_Raw, _Rx);
            _Other.release();
        }
    }

    ~shared_ptr() noexcept { // release resource
        this->_Decref();
    }

    shared_ptr& operator=(const shared_ptr& _Right) noexcept {
        shared_ptr(_Right).swap(*this);
        return *this;
    }

    template <class _Ty2>
    shared_ptr& operator=(const shared_ptr<_Ty2>& _Right) noexcept {
        shared_ptr(_Right).swap(*this);
        return *this;
    }

    shared_ptr& operator=(shared_ptr&& _Right) noexcept { // take resource from _Right
        shared_ptr(_STD move(_Right)).swap(*this);
        return *this;
    }

    template <class _Ty2>
    shared_ptr& operator=(shared_ptr<_Ty2>&& _Right) noexcept { // take resource from _Right
        shared_ptr(_STD move(_Right)).swap(*this);
        return *this;
    }

#if _HAS_AUTO_PTR_ETC
    template <class _Ty2>
    shared_ptr& operator=(auto_ptr<_Ty2>&& _Right) {
        shared_ptr(_STD move(_Right)).swap(*this);
        return *this;
    }
#endif // _HAS_AUTO_PTR_ETC

    template <class _Ux, class _Dx>
    shared_ptr& operator=(unique_ptr<_Ux, _Dx>&& _Right) { // move from unique_ptr
        shared_ptr(_STD move(_Right)).swap(*this);
        return *this;
    }

    void swap(shared_ptr& _Other) noexcept {
        this->_Swap(_Other);
    }

    void reset() noexcept { // release resource and convert to empty shared_ptr object
        shared_ptr().swap(*this);
    }

    template <class _Ux>
    void reset(_Ux* _Px) { // release, take ownership of _Px
        shared_ptr(_Px).swap(*this);
    }

    template <class _Ux, class _Dx>
    void reset(_Ux* _Px, _Dx _Dt) { // release, take ownership of _Px, with deleter _Dt
        shared_ptr(_Px, _Dt).swap(*this);
    }

    template <class _Ux, class _Dx, class _Alloc>
    void reset(_Ux* _Px, _Dx _Dt, _Alloc _Ax) { // release, take ownership of _Px, with deleter _Dt, allocator _Ax
        shared_ptr(_Px, _Dt, _Ax).swap(*this);
    }

    using _Mybase::get;

    template <class _Ty2 = _Ty, enable_if_t<!disjunction_v<is_array<_Ty2>, is_void<_Ty2>>, int> = 0>
    _NODISCARD _Ty2& operator*() const noexcept {
        return *get();
    }

    template <class _Ty2 = _Ty, enable_if_t<!is_array_v<_Ty2>, int> = 0>
    _NODISCARD _Ty2* operator->() const noexcept {
        return get();
    }

    template <class _Ty2 = _Ty, class _Elem = element_type, enable_if_t<is_array_v<_Ty2>, int> = 0>
    _NODISCARD _Elem& operator[](ptrdiff_t _Idx) const noexcept /* strengthened */ {
        return get()[_Idx];
    }

    _NODISCARD _CXX17_DEPRECATE_SHARED_PTR_UNIQUE bool unique() const noexcept {
        // return true if no other shared_ptr object owns this resource
        return this->use_count() == 1;
    }

    explicit operator bool() const noexcept {
        return get() != nullptr;
    }

private:
#if !_HAS_IF_CONSTEXPR
    template <class _Ux>
    void _Setp(_Ux* _Px, true_type) { // take ownership of _Px
        _Setpd(_Px, default_delete<_Ux[]>{});
    }

    template <class _Ux>
    void _Setp(_Ux* const _Px, false_type) { // take ownership of _Px
        _Temporary_owner<_Ux> _Owner(_Px);
        _Set_ptr_rep_and_enable_shared(_Owner._Ptr, new _Ref_count<_Ux>(_Owner._Ptr));
        _Owner._Ptr = nullptr;
    }
#endif // !_HAS_IF_CONSTEXPR

    template <class _UxptrOrNullptr, class _Dx>
    void _Setpd(const _UxptrOrNullptr _Px, _Dx _Dt) { // take ownership of _Px, deleter _Dt
        _Temporary_owner_del<_UxptrOrNullptr, _Dx> _Owner(_Px, _Dt);
        _Set_ptr_rep_and_enable_shared(
            _Owner._Ptr, new _Ref_count_resource<_UxptrOrNullptr, _Dx>(_Owner._Ptr, _STD move(_Dt)));
        _Owner._Call_deleter = false;
    }

    template <class _UxptrOrNullptr, class _Dx, class _Alloc>
    void _Setpda(const _UxptrOrNullptr _Px, _Dx _Dt, _Alloc _Ax) { // take ownership of _Px, deleter _Dt, allocator _Ax
        using _Alref_alloc = _Rebind_alloc_t<_Alloc, _Ref_count_resource_alloc<_UxptrOrNullptr, _Dx, _Alloc>>;

        _Temporary_owner_del<_UxptrOrNullptr, _Dx> _Owner(_Px, _Dt);
        _Alref_alloc _Alref(_Ax);
        _Alloc_construct_ptr<_Alref_alloc> _Constructor(_Alref);
        _Constructor._Allocate();
        _Construct_in_place(*_Constructor._Ptr, _Owner._Ptr, _STD move(_Dt), _Ax);
        _Set_ptr_rep_and_enable_shared(_Owner._Ptr, _Unfancy(_Constructor._Ptr));
        _Constructor._Ptr    = nullptr;
        _Owner._Call_deleter = false;
    }

    template <class _Ty0, class... _Types>
    friend shared_ptr<_Ty0> make_shared(_Types&&... _Args);

    template <class _Ty0, class _Alloc, class... _Types>
    friend shared_ptr<_Ty0> allocate_shared(const _Alloc& _Al_arg, _Types&&... _Args);

    template <class _Ux>
    void _Set_ptr_rep_and_enable_shared(_Ux* const _Px, _Ref_count_base* const _Rx) noexcept { // take ownership of _Px
        this->_Ptr = _Px;
        this->_Rep = _Rx;
#if _HAS_IF_CONSTEXPR
        if constexpr (conjunction_v<negation<is_array<_Ty>>, negation<is_volatile<_Ux>>, _Can_enable_shared<_Ux>>) {
            if (_Px && _Px->_Wptr.expired()) {
                _Px->_Wptr = shared_ptr<remove_cv_t<_Ux>>(*this, const_cast<remove_cv_t<_Ux>*>(_Px));
            }
        }
#else // ^^^ _HAS_IF_CONSTEXPR // !_HAS_IF_CONSTEXPR vvv
        _Enable_shared_from_this1(*this, _Px,
            bool_constant<
                conjunction_v<negation<is_array<_Ty>>, negation<is_volatile<_Ux>>, _Can_enable_shared<_Ux>>>{});
#endif // _HAS_IF_CONSTEXPR
    }

    void _Set_ptr_rep_and_enable_shared(nullptr_t, _Ref_count_base* const _Rx) noexcept { // take ownership of nullptr
        this->_Ptr = nullptr;
        this->_Rep = _Rx;
    }
};

#if _HAS_CXX17
template <class _Ty>
shared_ptr(weak_ptr<_Ty>)->shared_ptr<_Ty>;

template <class _Ty, class _Dx>
shared_ptr(unique_ptr<_Ty, _Dx>)->shared_ptr<_Ty>;
#endif // _HAS_CXX17

template <class _Ty1, class _Ty2>
_NODISCARD bool operator==(const shared_ptr<_Ty1>& _Left, const shared_ptr<_Ty2>& _Right) noexcept {
    return _Left.get() == _Right.get();
}

template <class _Ty1, class _Ty2>
_NODISCARD bool operator!=(const shared_ptr<_Ty1>& _Left, const shared_ptr<_Ty2>& _Right) noexcept {
    return _Left.get() != _Right.get();
}

template <class _Ty1, class _Ty2>
_NODISCARD bool operator<(const shared_ptr<_Ty1>& _Left, const shared_ptr<_Ty2>& _Right) noexcept {
    return _Left.get() < _Right.get();
}

template <class _Ty1, class _Ty2>
_NODISCARD bool operator>=(const shared_ptr<_Ty1>& _Left, const shared_ptr<_Ty2>& _Right) noexcept {
    return _Left.get() >= _Right.get();
}

template <class _Ty1, class _Ty2>
_NODISCARD bool operator>(const shared_ptr<_Ty1>& _Left, const shared_ptr<_Ty2>& _Right) noexcept {
    return _Left.get() > _Right.get();
}

template <class _Ty1, class _Ty2>
_NODISCARD bool operator<=(const shared_ptr<_Ty1>& _Left, const shared_ptr<_Ty2>& _Right) noexcept {
    return _Left.get() <= _Right.get();
}

template <class _Ty>
_NODISCARD bool operator==(const shared_ptr<_Ty>& _Left, nullptr_t) noexcept {
    return _Left.get() == nullptr;
}

template <class _Ty>
_NODISCARD bool operator==(nullptr_t, const shared_ptr<_Ty>& _Right) noexcept {
    return nullptr == _Right.get();
}

template <class _Ty>
_NODISCARD bool operator!=(const shared_ptr<_Ty>& _Left, nullptr_t) noexcept {
    return _Left.get() != nullptr;
}

template <class _Ty>
_NODISCARD bool operator!=(nullptr_t, const shared_ptr<_Ty>& _Right) noexcept {
    return nullptr != _Right.get();
}

template <class _Ty>
_NODISCARD bool operator<(const shared_ptr<_Ty>& _Left, nullptr_t) noexcept {
    return _Left.get() < static_cast<typename shared_ptr<_Ty>::element_type*>(nullptr);
}

template <class _Ty>
_NODISCARD bool operator<(nullptr_t, const shared_ptr<_Ty>& _Right) noexcept {
    return static_cast<typename shared_ptr<_Ty>::element_type*>(nullptr) < _Right.get();
}

template <class _Ty>
_NODISCARD bool operator>=(const shared_ptr<_Ty>& _Left, nullptr_t) noexcept {
    return _Left.get() >= static_cast<typename shared_ptr<_Ty>::element_type*>(nullptr);
}

template <class _Ty>
_NODISCARD bool operator>=(nullptr_t, const shared_ptr<_Ty>& _Right) noexcept {
    return static_cast<typename shared_ptr<_Ty>::element_type*>(nullptr) >= _Right.get();
}

template <class _Ty>
_NODISCARD bool operator>(const shared_ptr<_Ty>& _Left, nullptr_t) noexcept {
    return _Left.get() > static_cast<typename shared_ptr<_Ty>::element_type*>(nullptr);
}

template <class _Ty>
_NODISCARD bool operator>(nullptr_t, const shared_ptr<_Ty>& _Right) noexcept {
    return static_cast<typename shared_ptr<_Ty>::element_type*>(nullptr) > _Right.get();
}

template <class _Ty>
_NODISCARD bool operator<=(const shared_ptr<_Ty>& _Left, nullptr_t) noexcept {
    return _Left.get() <= static_cast<typename shared_ptr<_Ty>::element_type*>(nullptr);
}

template <class _Ty>
_NODISCARD bool operator<=(nullptr_t, const shared_ptr<_Ty>& _Right) noexcept {
    return static_cast<typename shared_ptr<_Ty>::element_type*>(nullptr) <= _Right.get();
}

template <class _Elem, class _Traits, class _Ty>
basic_ostream<_Elem, _Traits>& operator<<(basic_ostream<_Elem, _Traits>& _Out, const shared_ptr<_Ty>& _Px) {
    // write contained pointer to stream
    return _Out << _Px.get();
}

template <class _Ty>
void swap(shared_ptr<_Ty>& _Left, shared_ptr<_Ty>& _Right) noexcept {
    _Left.swap(_Right);
}

template <class _Ty1, class _Ty2>
_NODISCARD shared_ptr<_Ty1> static_pointer_cast(const shared_ptr<_Ty2>& _Other) noexcept {
    // static_cast for shared_ptr that properly respects the reference count control block
    const auto _Ptr = static_cast<typename shared_ptr<_Ty1>::element_type*>(_Other.get());
    return shared_ptr<_Ty1>(_Other, _Ptr);
}

template <class _Ty1, class _Ty2>
_NODISCARD shared_ptr<_Ty1> static_pointer_cast(shared_ptr<_Ty2>&& _Other) noexcept {
    // static_cast for shared_ptr that properly respects the reference count control block
    const auto _Ptr = static_cast<typename shared_ptr<_Ty1>::element_type*>(_Other.get());
    return shared_ptr<_Ty1>(_STD move(_Other), _Ptr);
}

template <class _Ty1, class _Ty2>
_NODISCARD shared_ptr<_Ty1> const_pointer_cast(const shared_ptr<_Ty2>& _Other) noexcept {
    // const_cast for shared_ptr that properly respects the reference count control block
    const auto _Ptr = const_cast<typename shared_ptr<_Ty1>::element_type*>(_Other.get());
    return shared_ptr<_Ty1>(_Other, _Ptr);
}

template <class _Ty1, class _Ty2>
_NODISCARD shared_ptr<_Ty1> const_pointer_cast(shared_ptr<_Ty2>&& _Other) noexcept {
    // const_cast for shared_ptr that properly respects the reference count control block
    const auto _Ptr = const_cast<typename shared_ptr<_Ty1>::element_type*>(_Other.get());
    return shared_ptr<_Ty1>(_STD move(_Other), _Ptr);
}

template <class _Ty1, class _Ty2>
_NODISCARD shared_ptr<_Ty1> reinterpret_pointer_cast(const shared_ptr<_Ty2>& _Other) noexcept {
    // reinterpret_cast for shared_ptr that properly respects the reference count control block
    const auto _Ptr = reinterpret_cast<typename shared_ptr<_Ty1>::element_type*>(_Other.get());
    return shared_ptr<_Ty1>(_Other, _Ptr);
}

template <class _Ty1, class _Ty2>
_NODISCARD shared_ptr<_Ty1> reinterpret_pointer_cast(shared_ptr<_Ty2>&& _Other) noexcept {
    // reinterpret_cast for shared_ptr that properly respects the reference count control block
    const auto _Ptr = reinterpret_cast<typename shared_ptr<_Ty1>::element_type*>(_Other.get());
    return shared_ptr<_Ty1>(_STD move(_Other), _Ptr);
}

#ifdef _CPPRTTI
template <class _Ty1, class _Ty2>
_NODISCARD shared_ptr<_Ty1> dynamic_pointer_cast(const shared_ptr<_Ty2>& _Other) noexcept {
    // dynamic_cast for shared_ptr that properly respects the reference count control block
    const auto _Ptr = dynamic_cast<typename shared_ptr<_Ty1>::element_type*>(_Other.get());

    if (_Ptr) {
        return shared_ptr<_Ty1>(_Other, _Ptr);
    }

    return shared_ptr<_Ty1>();
}

template <class _Ty1, class _Ty2>
_NODISCARD shared_ptr<_Ty1> dynamic_pointer_cast(shared_ptr<_Ty2>&& _Other) noexcept {
    // dynamic_cast for shared_ptr that properly respects the reference count control block
    const auto _Ptr = dynamic_cast<typename shared_ptr<_Ty1>::element_type*>(_Other.get());

    if (_Ptr) {
        return shared_ptr<_Ty1>(_STD move(_Other), _Ptr);
    }

    return shared_ptr<_Ty1>();
}
#else // _CPPRTTI
template <class _Ty1, class _Ty2>
shared_ptr<_Ty1> dynamic_pointer_cast(const shared_ptr<_Ty2>&) noexcept = delete; // requires /GR option
template <class _Ty1, class _Ty2>
shared_ptr<_Ty1> dynamic_pointer_cast(shared_ptr<_Ty2>&&) noexcept = delete; // requires /GR option
#endif // _CPPRTTI

#if _HAS_STATIC_RTTI
template <class _Dx, class _Ty>
_NODISCARD _Dx* get_deleter(const shared_ptr<_Ty>& _Sx) noexcept {
    // return pointer to shared_ptr's deleter object if its type is _Dx
    if (_Sx._Rep) {
        return static_cast<_Dx*>(_Sx._Rep->_Get_deleter(typeid(_Dx)));
    }

    return nullptr;
}
#else // _HAS_STATIC_RTTI
template <class _Dx, class _Ty>
_Dx* get_deleter(const shared_ptr<_Ty>&) noexcept = delete; // requires static RTTI
#endif // _HAS_STATIC_RTTI

// CLASS TEMPLATE _Ref_count_obj2
template <class _Ty>
class _Ref_count_obj2 : public _Ref_count_base { // handle reference counting for object in control block, no allocator
public:
    template <class... _Types>
    explicit _Ref_count_obj2(_Types&&... _Args) : _Ref_count_base() {
        _Construct_in_place(_Storage._Value, _STD forward<_Types>(_Args)...);
    }

    ~_Ref_count_obj2() {
        // nothing to do, _Storage._Value was already destroyed in _Destroy
    }

    union {
        _Wrap<_Ty> _Storage;
    };

private:
    virtual void _Destroy() noexcept override { // destroy managed resource
        _Destroy_in_place(_Storage._Value);
    }

    virtual void _Delete_this() noexcept override { // destroy self
        delete this;
    }
};

// CLASS TEMPLATE _Ebco_base
template <class _Ty,
    bool = is_empty_v<_Ty> && !is_final_v<_Ty>>
class _Ebco_base : private _Ty { // Empty Base Class Optimization, active
private:
    using _Mybase = _Ty; // for visualization

protected:
    template <class _Other, enable_if_t<!is_same_v<_Remove_cvref_t<_Other>, _Ebco_base>, int> = 0>
    explicit _Ebco_base(_Other&& _Val) noexcept(is_nothrow_constructible_v<_Ty, _Other>)
        : _Ty(_STD forward<_Other>(_Val)) {}

    _Ty& _Get_val() noexcept {
        return *this;
    }

    const _Ty& _Get_val() const noexcept {
        return *this;
    }
};

template <class _Ty>
class _Ebco_base<_Ty, false> { // Empty Base Class Optimization, inactive
private:
    _Ty _Myval;

protected:
    template <class _Other, enable_if_t<!is_same_v<_Remove_cvref_t<_Other>, _Ebco_base>, int> = 0>
    explicit _Ebco_base(_Other&& _Val) noexcept(is_nothrow_constructible_v<_Ty, _Other>)
        : _Myval(_STD forward<_Other>(_Val)) {}

    _Ty& _Get_val() noexcept {
        return _Myval;
    }

    const _Ty& _Get_val() const noexcept {
        return _Myval;
    }
};

// CLASS TEMPLATE _Ref_count_obj_alloc2
template <class _Ty, class _Alloc>
class __declspec(empty_bases) _Ref_count_obj_alloc2 : public _Ebco_base<_Alloc>, public _Ref_count_base {
    // handle reference counting for object in control block, allocator
public:
    template <class... _Types>
    explicit _Ref_count_obj_alloc2(const _Alloc& _Al_arg, _Types&&... _Args)
        : _Ebco_base<_Alloc>(_Al_arg), _Ref_count_base() {
        _Maybe_rebind_alloc_t<_Alloc, _Ty> _Alty(this->_Get_val());
        allocator_traits<_Rebind_alloc_t<_Alloc, _Ty>>::construct(
            _Alty, _STD addressof(_Storage._Value), _STD forward<_Types>(_Args)...);
    }

    union {
        _Wrap<_Ty> _Storage;
    };

private:
    ~_Ref_count_obj_alloc2() {
        // nothing to do; _Storage._Value already destroyed by _Destroy()
    }

    virtual void _Destroy() noexcept override { // destroy managed resource
        _Maybe_rebind_alloc_t<_Alloc, _Ty> _Alty(this->_Get_val());
        allocator_traits<_Rebind_alloc_t<_Alloc, _Ty>>::destroy(_Alty, _STD addressof(_Storage._Value));
    }

    virtual void _Delete_this() noexcept override { // destroy self
        _Rebind_alloc_t<_Alloc, _Ref_count_obj_alloc2> _Al(this->_Get_val());
        this->~_Ref_count_obj_alloc2();
        _Deallocate_plain(_Al, this);
    }
};

// FUNCTION TEMPLATE make_shared
template <class _Ty, class... _Types>
_NODISCARD shared_ptr<_Ty> make_shared(_Types&&... _Args) { // make a shared_ptr
    const auto _Rx = new _Ref_count_obj2<_Ty>(_STD forward<_Types>(_Args)...);
    shared_ptr<_Ty> _Ret;
    _Ret._Set_ptr_rep_and_enable_shared(_STD addressof(_Rx->_Storage._Value), _Rx);
    return _Ret;
}

// FUNCTION TEMPLATE allocate_shared
template <class _Ty, class _Alloc, class... _Types>
_NODISCARD shared_ptr<_Ty> allocate_shared(const _Alloc& _Al, _Types&&... _Args) { // make a shared_ptr
    // Note: As of 2019-05-28, this implements the proposed resolution of LWG-3210 (which controls whether
    // allocator::construct sees T or const T when _Ty is const qualified)
    using _Refoa   = _Ref_count_obj_alloc2<remove_cv_t<_Ty>, _Alloc>;
    using _Alblock = _Rebind_alloc_t<_Alloc, _Refoa>;
    _Alblock _Rebound(_Al);
    _Alloc_construct_ptr<_Alblock> _Constructor{_Rebound};
    _Constructor._Allocate();
    _Construct_in_place(*_Constructor._Ptr, _Al, _STD forward<_Types>(_Args)...);
    shared_ptr<_Ty> _Ret;
    const auto _Ptr = reinterpret_cast<_Ty*>(_STD addressof(_Constructor._Ptr->_Storage._Value));
    _Ret._Set_ptr_rep_and_enable_shared(_Ptr, _Unfancy(_Constructor._Release()));
    return _Ret;
}

// CLASS TEMPLATE weak_ptr
template <class _Ty>
class weak_ptr : public _Ptr_base<_Ty> { // class for pointer to reference counted resource
public:
    constexpr weak_ptr() noexcept {} // construct empty weak_ptr object

    weak_ptr(const weak_ptr& _Other) noexcept { // construct weak_ptr object for resource pointed to by _Other
        this->_Weakly_construct_from(_Other);
    }

    template <class _Ty2, enable_if_t<_SP_pointer_compatible<_Ty2, _Ty>::value, int> = 0>
    weak_ptr(const shared_ptr<_Ty2>& _Other) noexcept { // construct weak_ptr object for resource owned by _Other
        this->_Weakly_construct_from(_Other);
    }

    template <class _Ty2, enable_if_t<_SP_pointer_compatible<_Ty2, _Ty>::value, int> = 0>
    weak_ptr(const weak_ptr<_Ty2>& _Other) noexcept { // construct weak_ptr object for resource pointed to by _Other
        this->_Weakly_construct_from(_Other.lock());
    }

    weak_ptr(weak_ptr&& _Other) noexcept { // move construct from _Other
        this->_Move_construct_from(_STD move(_Other));
    }

    template <class _Ty2, enable_if_t<_SP_pointer_compatible<_Ty2, _Ty>::value, int> = 0>
    weak_ptr(weak_ptr<_Ty2>&& _Other) noexcept { // move construct from _Other
        this->_Weakly_construct_from(_Other.lock());
        _Other.reset();
    }

    ~weak_ptr() noexcept {
        this->_Decwref();
    }

    weak_ptr& operator=(const weak_ptr& _Right) noexcept {
        weak_ptr(_Right).swap(*this);
        return *this;
    }

    template <class _Ty2>
    weak_ptr& operator=(const weak_ptr<_Ty2>& _Right) noexcept {
        weak_ptr(_Right).swap(*this);
        return *this;
    }

    weak_ptr& operator=(weak_ptr&& _Right) noexcept {
        weak_ptr(_STD move(_Right)).swap(*this);
        return *this;
    }

    template <class _Ty2>
    weak_ptr& operator=(weak_ptr<_Ty2>&& _Right) noexcept {
        weak_ptr(_STD move(_Right)).swap(*this);
        return *this;
    }

    template <class _Ty2>
    weak_ptr& operator=(const shared_ptr<_Ty2>& _Right) noexcept {
        weak_ptr(_Right).swap(*this);
        return *this;
    }

    void reset() noexcept { // release resource, convert to null weak_ptr object
        weak_ptr().swap(*this);
    }

    void swap(weak_ptr& _Other) noexcept {
        this->_Swap(_Other);
    }

    _NODISCARD bool expired() const noexcept {
        return this->use_count() == 0;
    }

    _NODISCARD shared_ptr<_Ty> lock() const noexcept { // convert to shared_ptr
        shared_ptr<_Ty> _Ret;
        (void) _Ret._Construct_from_weak(*this);
        return _Ret;
    }
};

#if _HAS_CXX17
template <class _Ty>
weak_ptr(shared_ptr<_Ty>)->weak_ptr<_Ty>;
#endif // _HAS_CXX17

template <class _Ty>
void swap(weak_ptr<_Ty>& _Left, weak_ptr<_Ty>& _Right) noexcept {
    _Left.swap(_Right);
}

// CLASS TEMPLATE enable_shared_from_this
template <class _Ty>
class enable_shared_from_this { // provide member functions that create shared_ptr to this
public:
    using _Esft_type = enable_shared_from_this;

    _NODISCARD shared_ptr<_Ty> shared_from_this() {
        return shared_ptr<_Ty>(_Wptr);
    }

    _NODISCARD shared_ptr<const _Ty> shared_from_this() const {
        return shared_ptr<const _Ty>(_Wptr);
    }

    _NODISCARD weak_ptr<_Ty> weak_from_this() noexcept {
        return _Wptr;
    }

    _NODISCARD weak_ptr<const _Ty> weak_from_this() const noexcept {
        return _Wptr;
    }

protected:
    constexpr enable_shared_from_this() noexcept : _Wptr() {}

    enable_shared_from_this(const enable_shared_from_this&) noexcept : _Wptr() {
        // construct (must value-initialize _Wptr)
    }

    enable_shared_from_this& operator=(const enable_shared_from_this&) noexcept { // assign (must not change _Wptr)
        return *this;
    }

    ~enable_shared_from_this() = default;

private:
#if _HAS_IF_CONSTEXPR
    template <class _Yty>
    friend class shared_ptr;
#else // ^^^ _HAS_IF_CONSTEXPR // !_HAS_IF_CONSTEXPR vvv
    template <class _Other, class _Yty>
    friend void _Enable_shared_from_this1(const shared_ptr<_Other>& _This, _Yty* _Ptr, true_type) noexcept;
#endif // _HAS_IF_CONSTEXPR

    mutable weak_ptr<_Ty> _Wptr;
};


// CLASS TEMPLATE unique_ptr AND HELPERS

// STRUCT TEMPLATE default_delete
template <class _Ty>
struct default_delete { // default deleter for unique_ptr
    constexpr default_delete() noexcept = default;

    template <class _Ty2, enable_if_t<is_convertible_v<_Ty2*, _Ty*>, int> = 0>
    default_delete(const default_delete<_Ty2>&) noexcept {}

    void operator()(_Ty* _Ptr) const noexcept /* strengthened */ { // delete a pointer
        static_assert(0 < sizeof(_Ty), "can't delete an incomplete type");
        delete _Ptr;
    }
};

template <class _Ty>
struct default_delete<_Ty[]> { // default deleter for unique_ptr to array of unknown size
    constexpr default_delete() noexcept = default;

    template <class _Uty, enable_if_t<is_convertible_v<_Uty (*)[], _Ty (*)[]>, int> = 0>
    default_delete(const default_delete<_Uty[]>&) noexcept {}

    template <class _Uty, enable_if_t<is_convertible_v<_Uty (*)[], _Ty (*)[]>, int> = 0>
    void operator()(_Uty* _Ptr) const noexcept /* strengthened */ { // delete a pointer
        static_assert(0 < sizeof(_Uty), "can't delete an incomplete type");
        delete[] _Ptr;
    }
};

// STRUCT TEMPLATE _Get_deleter_pointer_type
template <class _Ty, class _Dx_noref, class = void>
struct _Get_deleter_pointer_type { // provide fallback
    using type = _Ty*;
};

template <class _Ty, class _Dx_noref>
struct _Get_deleter_pointer_type<_Ty, _Dx_noref, void_t<typename _Dx_noref::pointer>> { // get _Dx_noref::pointer
    using type = typename _Dx_noref::pointer;
};

template <class _Dx2>
using _Unique_ptr_enable_default_t =
    enable_if_t<conjunction_v<negation<is_pointer<_Dx2>>, is_default_constructible<_Dx2>>, int>;

// CLASS TEMPLATE unique_ptr SCALAR
template <class _Ty, class _Dx /* = default_delete<_Ty> */>
class unique_ptr { // non-copyable pointer to an object
public:
    using pointer      = typename _Get_deleter_pointer_type<_Ty, remove_reference_t<_Dx>>::type;
    using element_type = _Ty;
    using deleter_type = _Dx;

    template <class _Dx2 = _Dx, _Unique_ptr_enable_default_t<_Dx2> = 0>
    constexpr unique_ptr() noexcept : _Mypair(_Zero_then_variadic_args_t()) {}

    template <class _Dx2 = _Dx, _Unique_ptr_enable_default_t<_Dx2> = 0>
    constexpr unique_ptr(nullptr_t) noexcept : _Mypair(_Zero_then_variadic_args_t()) {}

    unique_ptr& operator=(nullptr_t) noexcept {
        reset();
        return *this;
    }

    template <class _Dx2 = _Dx, _Unique_ptr_enable_default_t<_Dx2> = 0>
    explicit unique_ptr(pointer _Ptr) noexcept : _Mypair(_Zero_then_variadic_args_t(), _Ptr) {}

    template <class _Dx2 = _Dx, enable_if_t<is_constructible_v<_Dx2, const _Dx2&>, int> = 0>
    unique_ptr(pointer _Ptr, const _Dx& _Dt) noexcept : _Mypair(_One_then_variadic_args_t(), _Dt, _Ptr) {}

    template <class _Dx2                                                                            = _Dx,
        enable_if_t<conjunction_v<negation<is_reference<_Dx2>>, is_constructible<_Dx2, _Dx2>>, int> = 0>
    unique_ptr(pointer _Ptr, _Dx&& _Dt) noexcept : _Mypair(_One_then_variadic_args_t(), _STD move(_Dt), _Ptr) {}

    template <class _Dx2                                                                                      = _Dx,
        enable_if_t<conjunction_v<is_reference<_Dx2>, is_constructible<_Dx2, remove_reference_t<_Dx2>>>, int> = 0>
    unique_ptr(pointer, remove_reference_t<_Dx>&&) = delete;

#ifndef _M_CEE // TRANSITION, VSO-1006185
    template <class _Dx2 = _Dx, enable_if_t<is_move_constructible_v<_Dx2>, int> = 0>
#endif // _M_CEE
    unique_ptr(unique_ptr&& _Right) noexcept
        : _Mypair(_One_then_variadic_args_t(), _STD forward<_Dx>(_Right.get_deleter()), _Right.release()) {
    }

    template <class _Ty2, class _Dx2,
        enable_if_t<
            conjunction_v<negation<is_array<_Ty2>>, is_convertible<typename unique_ptr<_Ty2, _Dx2>::pointer, pointer>,
                conditional_t<is_reference_v<_Dx>, is_same<_Dx2, _Dx>, is_convertible<_Dx2, _Dx>>>,
            int> = 0>
    unique_ptr(unique_ptr<_Ty2, _Dx2>&& _Right) noexcept
        : _Mypair(_One_then_variadic_args_t(), _STD forward<_Dx2>(_Right.get_deleter()), _Right.release()) {}

#if _HAS_AUTO_PTR_ETC
    template <class _Ty2,
        enable_if_t<conjunction_v<is_convertible<_Ty2*, _Ty*>, is_same<_Dx, default_delete<_Ty>>>, int> = 0>
    unique_ptr(auto_ptr<_Ty2>&& _Right) noexcept : _Mypair(_Zero_then_variadic_args_t(), _Right.release()) {}
#endif // _HAS_AUTO_PTR_ETC

    template <class _Ty2, class _Dx2,
        enable_if_t<conjunction_v<negation<is_array<_Ty2>>, is_assignable<_Dx&, _Dx2>,
                        is_convertible<typename unique_ptr<_Ty2, _Dx2>::pointer, pointer>>,
            int> = 0>
    unique_ptr& operator=(unique_ptr<_Ty2, _Dx2>&& _Right) noexcept {
        reset(_Right.release());
        _Mypair._Get_first() = _STD forward<_Dx2>(_Right._Mypair._Get_first());
        return *this;
    }

#ifndef _M_CEE // TRANSITION, VSO-1006185
    template <class _Dx2 = _Dx, enable_if_t<is_move_assignable_v<_Dx2>, int> = 0>
#endif // _M_CEE
    unique_ptr& operator=(unique_ptr&& _Right) noexcept {
        if (this != _STD addressof(_Right)) {
            reset(_Right.release());
            _Mypair._Get_first() = _STD forward<_Dx>(_Right._Mypair._Get_first());
        }
        return *this;
    }

    void swap(unique_ptr& _Right) noexcept {
        _Swap_adl(_Mypair._Myval2, _Right._Mypair._Myval2);
        _Swap_adl(_Mypair._Get_first(), _Right._Mypair._Get_first());
    }

    ~unique_ptr() noexcept {
        if (_Mypair._Myval2) {
            _Mypair._Get_first()(_Mypair._Myval2);
        }
    }

    _NODISCARD _Dx& get_deleter() noexcept {
        return _Mypair._Get_first();
    }

    _NODISCARD const _Dx& get_deleter() const noexcept {
        return _Mypair._Get_first();
    }

    _NODISCARD add_lvalue_reference_t<_Ty> operator*() const noexcept /* strengthened */ {
        return *_Mypair._Myval2;
    }

    _NODISCARD pointer operator->() const noexcept {
        return _Mypair._Myval2;
    }

    _NODISCARD pointer get() const noexcept {
        return _Mypair._Myval2;
    }

    explicit operator bool() const noexcept {
        return static_cast<bool>(_Mypair._Myval2);
    }

    pointer release() noexcept {
        return _STD exchange(_Mypair._Myval2, pointer());
    }

    void reset(pointer _Ptr = pointer()) noexcept {
        pointer _Old = _STD exchange(_Mypair._Myval2, _Ptr);
        if (_Old) {
            _Mypair._Get_first()(_Old);
        }
    }

    unique_ptr(const unique_ptr&) = delete;
    unique_ptr& operator=(const unique_ptr&) = delete;

private:
    template <class, class>
    friend class unique_ptr;

    _Compressed_pair<_Dx, pointer> _Mypair;
};

// CLASS TEMPLATE unique_ptr ARRAY
template <class _Ty, class _Dx>
class unique_ptr<_Ty[], _Dx> { // non-copyable pointer to an array object
public:
    using pointer      = typename _Get_deleter_pointer_type<_Ty, remove_reference_t<_Dx>>::type;
    using element_type = _Ty;
    using deleter_type = _Dx;

    template <class _Dx2 = _Dx, _Unique_ptr_enable_default_t<_Dx2> = 0>
    constexpr unique_ptr() noexcept : _Mypair(_Zero_then_variadic_args_t()) {}

    template <class _Uty, class _Is_nullptr = is_same<_Uty, nullptr_t>>
    using _Enable_ctor_reset = enable_if_t<is_same_v<_Uty, pointer> //
                                           || _Is_nullptr::value //
                                           || (is_same_v<pointer, element_type*> //
                                               && is_pointer_v<_Uty> //
                                               && is_convertible_v<remove_pointer_t<_Uty> (*)[], element_type (*)[]>)>;

    template <class _Uty, class _Dx2 = _Dx, _Unique_ptr_enable_default_t<_Dx2> = 0, class = _Enable_ctor_reset<_Uty>>
    explicit unique_ptr(_Uty _Ptr) noexcept : _Mypair(_Zero_then_variadic_args_t(), _Ptr) {}

    template <class _Uty, class _Dx2 = _Dx, enable_if_t<is_constructible_v<_Dx2, const _Dx2&>, int> = 0,
        class = _Enable_ctor_reset<_Uty>>
    unique_ptr(_Uty _Ptr, const _Dx& _Dt) noexcept : _Mypair(_One_then_variadic_args_t(), _Dt, _Ptr) {}

    template <class _Uty, class _Dx2 = _Dx,
        enable_if_t<conjunction_v<negation<is_reference<_Dx2>>, is_constructible<_Dx2, _Dx2>>, int> = 0,
        class = _Enable_ctor_reset<_Uty>>
    unique_ptr(_Uty _Ptr, _Dx&& _Dt) noexcept : _Mypair(_One_then_variadic_args_t(), _STD move(_Dt), _Ptr) {}

    template <class _Uty, class _Dx2 = _Dx,
        enable_if_t<conjunction_v<is_reference<_Dx2>, is_constructible<_Dx2, remove_reference_t<_Dx2>>>, int> = 0>
    unique_ptr(_Uty, remove_reference_t<_Dx>&&) = delete;

#ifndef _M_CEE // TRANSITION, VSO-1006185
    template <class _Dx2 = _Dx, enable_if_t<is_move_constructible_v<_Dx2>, int> = 0>
#endif // _M_CEE
    unique_ptr(unique_ptr&& _Right) noexcept
        : _Mypair(_One_then_variadic_args_t(), _STD forward<_Dx>(_Right.get_deleter()), _Right.release()) {
    }

#ifndef _M_CEE // TRANSITION, VSO-1006185
    template <class _Dx2 = _Dx, enable_if_t<is_move_assignable_v<_Dx2>, int> = 0>
#endif // _M_CEE
    unique_ptr& operator=(unique_ptr&& _Right) noexcept {
        if (this != _STD addressof(_Right)) {
            reset(_Right.release());
            _Mypair._Get_first() = _STD move(_Right._Mypair._Get_first());
        }

        return *this;
    }

    template <class _Uty, class _Ex, class _More, class _UP_pointer = typename unique_ptr<_Uty, _Ex>::pointer,
        class _UP_element_type = typename unique_ptr<_Uty, _Ex>::element_type>
    using _Enable_conversion = enable_if_t<conjunction_v<is_array<_Uty>, is_same<pointer, element_type*>,
        is_same<_UP_pointer, _UP_element_type*>, is_convertible<_UP_element_type (*)[], element_type (*)[]>, _More>>;

    template <class _Uty, class _Ex,
        class = _Enable_conversion<_Uty, _Ex,
            conditional_t<is_reference_v<_Dx>, is_same<_Ex, _Dx>, is_convertible<_Ex, _Dx>>>>
    unique_ptr(unique_ptr<_Uty, _Ex>&& _Right) noexcept
        : _Mypair(_One_then_variadic_args_t(), _STD forward<_Ex>(_Right.get_deleter()), _Right.release()) {}

    template <class _Uty, class _Ex, class = _Enable_conversion<_Uty, _Ex, is_assignable<_Dx&, _Ex>>>
    unique_ptr& operator=(unique_ptr<_Uty, _Ex>&& _Right) noexcept {
        reset(_Right.release());
        _Mypair._Get_first() = _STD forward<_Ex>(_Right._Mypair._Get_first());
        return *this;
    }

    template <class _Dx2 = _Dx, _Unique_ptr_enable_default_t<_Dx2> = 0>
    constexpr unique_ptr(nullptr_t) noexcept : _Mypair(_Zero_then_variadic_args_t()) {}

    unique_ptr& operator=(nullptr_t) noexcept {
        reset();
        return *this;
    }

    void reset(nullptr_t = nullptr) noexcept {
        reset(pointer());
    }

    void swap(unique_ptr& _Right) noexcept {
        _Swap_adl(_Mypair._Myval2, _Right._Mypair._Myval2);
        _Swap_adl(_Mypair._Get_first(), _Right._Mypair._Get_first());
    }

    ~unique_ptr() noexcept {
        if (_Mypair._Myval2) {
            _Mypair._Get_first()(_Mypair._Myval2);
        }
    }

    _NODISCARD _Dx& get_deleter() noexcept {
        return _Mypair._Get_first();
    }

    _NODISCARD const _Dx& get_deleter() const noexcept {
        return _Mypair._Get_first();
    }

    _NODISCARD _Ty& operator[](size_t _Idx) const noexcept /* strengthened */ {
        return _Mypair._Myval2[_Idx];
    }

    _NODISCARD pointer get() const noexcept {
        return _Mypair._Myval2;
    }

    explicit operator bool() const noexcept {
        return static_cast<bool>(_Mypair._Myval2);
    }

    pointer release() noexcept {
        return _STD exchange(_Mypair._Myval2, pointer());
    }

    template <class _Uty, class = _Enable_ctor_reset<_Uty, false_type>>
    void reset(_Uty _Ptr) noexcept {
        pointer _Old = _STD exchange(_Mypair._Myval2, _Ptr);
        if (_Old) {
            _Mypair._Get_first()(_Old);
        }
    }

    unique_ptr(const unique_ptr&) = delete;
    unique_ptr& operator=(const unique_ptr&) = delete;

private:
    template <class, class>
    friend class unique_ptr;

    _Compressed_pair<_Dx, pointer> _Mypair;
};


// FUNCTION TEMPLATE make_unique
template <class _Ty, class... _Types, enable_if_t<!is_array_v<_Ty>, int> = 0>
_NODISCARD unique_ptr<_Ty> make_unique(_Types&&... _Args) { // make a unique_ptr
    return unique_ptr<_Ty>(new _Ty(_STD forward<_Types>(_Args)...));
}

template <class _Ty, enable_if_t<is_array_v<_Ty> && extent_v<_Ty> == 0, int> = 0>
_NODISCARD unique_ptr<_Ty> make_unique(size_t _Size) { // make a unique_ptr
    using _Elem = remove_extent_t<_Ty>;
    return unique_ptr<_Ty>(new _Elem[_Size]());
}

template <class _Ty, class... _Types, enable_if_t<extent_v<_Ty> != 0, int> = 0>
void make_unique(_Types&&...) = delete;

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

template <class _Ty1, class _Dx1, class _Ty2, class _Dx2>
_NODISCARD bool operator==(const unique_ptr<_Ty1, _Dx1>& _Left, const unique_ptr<_Ty2, _Dx2>& _Right) {
    return _Left.get() == _Right.get();
}

template <class _Ty1, class _Dx1, class _Ty2, class _Dx2>
_NODISCARD bool operator!=(const unique_ptr<_Ty1, _Dx1>& _Left, const unique_ptr<_Ty2, _Dx2>& _Right) {
    return !(_Left == _Right);
}

template <class _Ty1, class _Dx1, class _Ty2, class _Dx2>
_NODISCARD bool operator<(const unique_ptr<_Ty1, _Dx1>& _Left, const unique_ptr<_Ty2, _Dx2>& _Right) {
    using _Ptr1   = typename unique_ptr<_Ty1, _Dx1>::pointer;
    using _Ptr2   = typename unique_ptr<_Ty2, _Dx2>::pointer;
    using _Common = common_type_t<_Ptr1, _Ptr2>;
    return less<_Common>()(_Left.get(), _Right.get());
}

template <class _Ty1, class _Dx1, class _Ty2, class _Dx2>
_NODISCARD bool operator>=(const unique_ptr<_Ty1, _Dx1>& _Left, const unique_ptr<_Ty2, _Dx2>& _Right) {
    return !(_Left < _Right);
}

template <class _Ty1, class _Dx1, class _Ty2, class _Dx2>
_NODISCARD bool operator>(const unique_ptr<_Ty1, _Dx1>& _Left, const unique_ptr<_Ty2, _Dx2>& _Right) {
    return _Right < _Left;
}

template <class _Ty1, class _Dx1, class _Ty2, class _Dx2>
_NODISCARD bool operator<=(const unique_ptr<_Ty1, _Dx1>& _Left, const unique_ptr<_Ty2, _Dx2>& _Right) {
    return !(_Right < _Left);
}

template <class _Ty, class _Dx>
_NODISCARD bool operator==(const unique_ptr<_Ty, _Dx>& _Left, nullptr_t) noexcept {
    return !_Left;
}

template <class _Ty, class _Dx>
_NODISCARD bool operator==(nullptr_t, const unique_ptr<_Ty, _Dx>& _Right) noexcept {
    return !_Right;
}

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

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

template <class _Ty, class _Dx>
_NODISCARD bool operator<(const unique_ptr<_Ty, _Dx>& _Left, nullptr_t _Right) {
    using _Ptr = typename unique_ptr<_Ty, _Dx>::pointer;
    return less<_Ptr>()(_Left.get(), _Right);
}

template <class _Ty, class _Dx>
_NODISCARD bool operator<(nullptr_t _Left, const unique_ptr<_Ty, _Dx>& _Right) {
    using _Ptr = typename unique_ptr<_Ty, _Dx>::pointer;
    return less<_Ptr>()(_Left, _Right.get());
}

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

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

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

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

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

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

template <class _OutTy, class _PxTy, class = void>
struct _Can_stream_unique_ptr : false_type {};
template <class _OutTy, class _PxTy>
struct _Can_stream_unique_ptr<_OutTy, _PxTy, void_t<decltype(_STD declval<_OutTy>() << _STD declval<_PxTy>().get())>>
    : true_type {};

template <class _Elem, class _Traits, class _Yty, class _Dx,
    enable_if_t<_Can_stream_unique_ptr<basic_ostream<_Elem, _Traits>&, const unique_ptr<_Yty, _Dx>&>::value, int> = 0>
basic_ostream<_Elem, _Traits>& operator<<(basic_ostream<_Elem, _Traits>& _Out, const unique_ptr<_Yty, _Dx>& _Px) {
    // write contained pointer to stream
    _Out << _Px.get();
    return _Out;
}

// GARBAGE COLLECTION
enum class pointer_safety { relaxed, preferred, strict };

inline void declare_reachable(void*) {}

template <class _Ty>
_Ty* undeclare_reachable(_Ty* _Ptr) {
    return _Ptr;
}

inline void declare_no_pointers(char*, size_t) {}

inline void undeclare_no_pointers(char*, size_t) {}

inline pointer_safety get_pointer_safety() noexcept {
    return pointer_safety::relaxed;
}

// STRUCT TEMPLATE owner_less
template <class _Ty = void>
struct owner_less; // not defined

template <class _Ty>
struct owner_less<shared_ptr<_Ty>> {
    _CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef shared_ptr<_Ty> first_argument_type;
    _CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef shared_ptr<_Ty> second_argument_type;
    _CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef bool result_type;

    _NODISCARD bool operator()(const shared_ptr<_Ty>& _Left, const shared_ptr<_Ty>& _Right) const noexcept {
        return _Left.owner_before(_Right);
    }

    _NODISCARD bool operator()(const shared_ptr<_Ty>& _Left, const weak_ptr<_Ty>& _Right) const noexcept {
        return _Left.owner_before(_Right);
    }

    _NODISCARD bool operator()(const weak_ptr<_Ty>& _Left, const shared_ptr<_Ty>& _Right) const noexcept {
        return _Left.owner_before(_Right);
    }
};

template <class _Ty>
struct owner_less<weak_ptr<_Ty>> {
    _CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef weak_ptr<_Ty> first_argument_type;
    _CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef weak_ptr<_Ty> second_argument_type;
    _CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef bool result_type;

    _NODISCARD bool operator()(const weak_ptr<_Ty>& _Left, const weak_ptr<_Ty>& _Right) const noexcept {
        return _Left.owner_before(_Right);
    }

    _NODISCARD bool operator()(const weak_ptr<_Ty>& _Left, const shared_ptr<_Ty>& _Right) const noexcept {
        return _Left.owner_before(_Right);
    }

    _NODISCARD bool operator()(const shared_ptr<_Ty>& _Left, const weak_ptr<_Ty>& _Right) const noexcept {
        return _Left.owner_before(_Right);
    }
};

template <>
struct owner_less<void> {
    using is_transparent = int;

    template <class _Ty, class _Uty>
    _NODISCARD bool operator()(const shared_ptr<_Ty>& _Left, const shared_ptr<_Uty>& _Right) const noexcept {
        return _Left.owner_before(_Right);
    }

    template <class _Ty, class _Uty>
    _NODISCARD bool operator()(const shared_ptr<_Ty>& _Left, const weak_ptr<_Uty>& _Right) const noexcept {
        return _Left.owner_before(_Right);
    }

    template <class _Ty, class _Uty>
    _NODISCARD bool operator()(const weak_ptr<_Ty>& _Left, const shared_ptr<_Uty>& _Right) const noexcept {
        return _Left.owner_before(_Right);
    }

    template <class _Ty, class _Uty>
    _NODISCARD bool operator()(const weak_ptr<_Ty>& _Left, const weak_ptr<_Uty>& _Right) const noexcept {
        return _Left.owner_before(_Right);
    }
};

// STRUCT TEMPLATE SPECIALIZATION hash
template <class _Ty, class _Dx>
struct hash<unique_ptr<_Ty, _Dx>> : _Conditionally_enabled_hash<unique_ptr<_Ty, _Dx>,
                                        is_default_constructible_v<hash<typename unique_ptr<_Ty, _Dx>::pointer>>> {
    static size_t _Do_hash(const unique_ptr<_Ty, _Dx>& _Keyval) noexcept(
        _Is_nothrow_hashable<typename unique_ptr<_Ty, _Dx>::pointer>::value) {
        return hash<typename unique_ptr<_Ty, _Dx>::pointer>{}(_Keyval.get());
    }
};

template <class _Ty>
struct hash<shared_ptr<_Ty>> {
    _CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef shared_ptr<_Ty> argument_type;
    _CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef size_t result_type;

    _NODISCARD size_t operator()(const shared_ptr<_Ty>& _Keyval) const noexcept {
        return hash<typename shared_ptr<_Ty>::element_type*>()(_Keyval.get());
    }
};

// FUNCTION align
inline void* align(size_t _Bound, size_t _Size, void*& _Ptr, size_t& _Space) noexcept /* strengthened */ {
    // try to carve out _Size bytes on boundary _Bound
    size_t _Off = static_cast<size_t>(reinterpret_cast<uintptr_t>(_Ptr) & (_Bound - 1));
    if (_Off != 0) {
        _Off = _Bound - _Off; // number of bytes to skip
    }

    if (_Space < _Off || _Space - _Off < _Size) {
        return nullptr;
    }

    // enough room, update
    _Ptr = static_cast<char*>(_Ptr) + _Off;
    _Space -= _Off;
    return _Ptr;
}

#if _HAS_CXX20 && 0
template <size_t _N0, class _Ty>
_NODISCARD constexpr _Ty* assume_aligned(_Ty* _Ptr) noexcept /* strengthened */ {
    // this enforces the requirement that _N0 be a power of two
    __builtin_assume_aligned(_Ptr, _N0);

    return _Ptr;
}
#endif // _HAS_CXX20 && 0

// SPIN LOCKS
_EXTERN_C
_CRTIMP2_PURE void __cdecl _Lock_shared_ptr_spin_lock();
_CRTIMP2_PURE void __cdecl _Unlock_shared_ptr_spin_lock();
_END_EXTERN_C

// WRAP SPIN-LOCK
struct _Shared_ptr_spin_lock { // class to manage a spin lock for shared_ptr atomic operations
    _Shared_ptr_spin_lock() { // lock the spin lock
        _Lock_shared_ptr_spin_lock();
    }

    ~_Shared_ptr_spin_lock() noexcept { // unlock the spin lock
        _Unlock_shared_ptr_spin_lock();
    }
};

template <class _Ty>
_NODISCARD bool atomic_is_lock_free(const shared_ptr<_Ty>*) {
    // return true if atomic operations on shared_ptr<_Ty> are lock-free
    return false;
}

template <class _Ty>
_NODISCARD shared_ptr<_Ty> atomic_load_explicit(const shared_ptr<_Ty>* _Ptr, memory_order) {
    // load *_Ptr atomically
    _Shared_ptr_spin_lock _Lock;
    shared_ptr<_Ty> _Result = *_Ptr;
    return _Result;
}

template <class _Ty>
_NODISCARD shared_ptr<_Ty> atomic_load(const shared_ptr<_Ty>* _Ptr) { // load *_Ptr atomically
    return _STD atomic_load_explicit(_Ptr, memory_order_seq_cst);
}

template <class _Ty>
void atomic_store_explicit(shared_ptr<_Ty>* _Ptr, shared_ptr<_Ty> _Other, memory_order) {
    // store _Other to *_Ptr atomically
    _Shared_ptr_spin_lock _Lock;
    _Ptr->swap(_Other);
}

template <class _Ty>
void atomic_store(shared_ptr<_Ty>* _Ptr, shared_ptr<_Ty> _Other) { // store _Other to *_Ptr atomically
    _STD atomic_store_explicit(_Ptr, _STD move(_Other), memory_order_seq_cst);
}

template <class _Ty>
shared_ptr<_Ty> atomic_exchange_explicit(shared_ptr<_Ty>* _Ptr, shared_ptr<_Ty> _Other, memory_order) {
    // copy _Other to *_Ptr and return previous value of *_Ptr atomically
    _Shared_ptr_spin_lock _Lock;
    _Ptr->swap(_Other);
    return _Other;
}

template <class _Ty>
shared_ptr<_Ty> atomic_exchange(shared_ptr<_Ty>* _Ptr, shared_ptr<_Ty> _Other) {
    // copy _Other to *_Ptr and return previous value of *_Ptr atomically
    return _STD atomic_exchange_explicit(_Ptr, _STD move(_Other), memory_order_seq_cst);
}

template <class _Ty>
bool atomic_compare_exchange_weak_explicit(shared_ptr<_Ty>* _Ptr, shared_ptr<_Ty>* _Exp, shared_ptr<_Ty> _Value,
    memory_order, memory_order) { // atomically compare and exchange
    shared_ptr<_Ty> _Old_exp; // destroyed outside spin lock
    _Shared_ptr_spin_lock _Lock;
    bool _Success = _Ptr->get() == _Exp->get() && !_Ptr->owner_before(*_Exp) && !_Exp->owner_before(*_Ptr);
    if (_Success) {
        _Ptr->swap(_Value);
    } else { // match failed
        _Exp->swap(_Old_exp);
        *_Exp = *_Ptr;
    }
    return _Success;
}

template <class _Ty>
bool atomic_compare_exchange_weak(shared_ptr<_Ty>* _Ptr, shared_ptr<_Ty>* _Exp, shared_ptr<_Ty> _Value) {
    // atomically compare and exchange
    return _STD atomic_compare_exchange_weak_explicit(
        _Ptr, _Exp, _STD move(_Value), memory_order_seq_cst, memory_order_seq_cst);
}

template <class _Ty>
bool atomic_compare_exchange_strong_explicit(shared_ptr<_Ty>* _Ptr, shared_ptr<_Ty>* _Exp, shared_ptr<_Ty> _Value,
    memory_order, memory_order) { // atomically compare and exchange
    return _STD atomic_compare_exchange_weak_explicit(
        _Ptr, _Exp, _STD move(_Value), memory_order_seq_cst, memory_order_seq_cst);
}

template <class _Ty>
bool atomic_compare_exchange_strong(shared_ptr<_Ty>* _Ptr, shared_ptr<_Ty>* _Exp, shared_ptr<_Ty> _Value) {
    // atomically compare and exchange
    return _STD atomic_compare_exchange_strong_explicit(
        _Ptr, _Exp, _STD move(_Value), memory_order_seq_cst, memory_order_seq_cst);
}

#if _HAS_TR1_NAMESPACE
namespace _DEPRECATE_TR1_NAMESPACE tr1 {
    using _STD allocate_shared;
    using _STD bad_weak_ptr;
    using _STD const_pointer_cast;
    using _STD dynamic_pointer_cast;
    using _STD enable_shared_from_this;
    using _STD get_deleter;
    using _STD make_shared;
    using _STD shared_ptr;
    using _STD static_pointer_cast;
    using _STD swap;
    using _STD weak_ptr;
} // 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 // _MEMORY_