llvm-project/libcxx/include/scoped_allocator

// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP_SCOPED_ALLOCATOR
#define _LIBCPP_SCOPED_ALLOCATOR

/*
    scoped_allocator synopsis

namespace std
{

template <class OuterAlloc, class... InnerAllocs>
class scoped_allocator_adaptor : public OuterAlloc
{
    typedef allocator_traits<OuterAlloc> OuterTraits; // exposition only
    scoped_allocator_adaptor<InnerAllocs...> inner;   // exposition only
public:

    typedef OuterAlloc outer_allocator_type;
    typedef see below inner_allocator_type;

    typedef typename OuterTraits::value_type value_type;
    typedef typename OuterTraits::size_type size_type;
    typedef typename OuterTraits::difference_type difference_type;
    typedef typename OuterTraits::pointer pointer;
    typedef typename OuterTraits::const_pointer const_pointer;
    typedef typename OuterTraits::void_pointer void_pointer;
    typedef typename OuterTraits::const_void_pointer const_void_pointer;

    typedef see below propagate_on_container_copy_assignment;
    typedef see below propagate_on_container_move_assignment;
    typedef see below propagate_on_container_swap;
    typedef see below is_always_equal;

    template <class Tp>
        struct rebind
        {
            typedef scoped_allocator_adaptor<
                OuterTraits::template rebind_alloc<Tp>, InnerAllocs...> other;
        };

    scoped_allocator_adaptor();
    template <class OuterA2>
        scoped_allocator_adaptor(OuterA2&& outerAlloc,
                                 const InnerAllocs&... innerAllocs) noexcept;
    scoped_allocator_adaptor(const scoped_allocator_adaptor& other) noexcept;
    scoped_allocator_adaptor(scoped_allocator_adaptor&& other) noexcept;
    template <class OuterA2>
        scoped_allocator_adaptor(const scoped_allocator_adaptor<OuterA2, InnerAllocs...>& other) noexcept;
    template <class OuterA2>
        scoped_allocator_adaptor(const scoped_allocator_adaptor<OuterA2, InnerAllocs...>&& other) noexcept;

    scoped_allocator_adaptor& operator=(const scoped_allocator_adaptor&) = default;
    scoped_allocator_adaptor& operator=(scoped_allocator_adaptor&&) = default;
    ~scoped_allocator_adaptor();

    inner_allocator_type& inner_allocator() noexcept;
    const inner_allocator_type& inner_allocator() const noexcept;

    outer_allocator_type& outer_allocator() noexcept;
    const outer_allocator_type& outer_allocator() const noexcept;

    pointer allocate(size_type n);                           // [[nodiscard]] in C++20
    pointer allocate(size_type n, const_void_pointer hint);  // [[nodiscard]] in C++20
    void deallocate(pointer p, size_type n) noexcept;

    size_type max_size() const;
    template <class T, class... Args> void construct(T* p, Args&& args);
    template <class T1, class T2, class... Args1, class... Args2>
        void construct(pair<T1, T2>* p, piecewise_construct t, tuple<Args1...> x,
                       tuple<Args2...> y);
    template <class T1, class T2>
        void construct(pair<T1, T2>* p);
    template <class T1, class T2, class U, class V>
        void construct(pair<T1, T2>* p, U&& x, V&& y);
    template <class T1, class T2, class U, class V>
        void construct(pair<T1, T2>* p, const pair<U, V>& x);
    template <class T1, class T2, class U, class V>
        void construct(pair<T1, T2>* p, pair<U, V>&& x);
    template <class T> void destroy(T* p);

    template <class T> void destroy(T* p) noexcept;

    scoped_allocator_adaptor select_on_container_copy_construction() const noexcept;
};

template<class OuterAlloc, class... InnerAllocs>
    scoped_allocator_adaptor(OuterAlloc, InnerAllocs...)
        -> scoped_allocator_adaptor<OuterAlloc, InnerAllocs...>;

template <class OuterA1, class OuterA2, class... InnerAllocs>
    bool
    operator==(const scoped_allocator_adaptor<OuterA1, InnerAllocs...>& a,
               const scoped_allocator_adaptor<OuterA2, InnerAllocs...>& b) noexcept;

template <class OuterA1, class OuterA2, class... InnerAllocs>
    bool
    operator!=(const scoped_allocator_adaptor<OuterA1, InnerAllocs...>& a,
               const scoped_allocator_adaptor<OuterA2, InnerAllocs...>& b) noexcept;

}  // std

*/

#include <__config>
#include <__utility/forward.h>
#include <memory>
#include <version>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

#if !defined(_LIBCPP_CXX03_LANG)

// scoped_allocator_adaptor

template <class ..._Allocs>
class scoped_allocator_adaptor;

template <class ..._Allocs> struct __get_poc_copy_assignment;

template <class _A0>
struct __get_poc_copy_assignment<_A0>
{
    static const bool value = allocator_traits<_A0>::
                              propagate_on_container_copy_assignment::value;
};

template <class _A0, class ..._Allocs>
struct __get_poc_copy_assignment<_A0, _Allocs...>
{
    static const bool value =
        allocator_traits<_A0>::propagate_on_container_copy_assignment::value ||
        __get_poc_copy_assignment<_Allocs...>::value;
};

template <class ..._Allocs> struct __get_poc_move_assignment;

template <class _A0>
struct __get_poc_move_assignment<_A0>
{
    static const bool value = allocator_traits<_A0>::
                              propagate_on_container_move_assignment::value;
};

template <class _A0, class ..._Allocs>
struct __get_poc_move_assignment<_A0, _Allocs...>
{
    static const bool value =
        allocator_traits<_A0>::propagate_on_container_move_assignment::value ||
        __get_poc_move_assignment<_Allocs...>::value;
};

template <class ..._Allocs> struct __get_poc_swap;

template <class _A0>
struct __get_poc_swap<_A0>
{
    static const bool value = allocator_traits<_A0>::
                              propagate_on_container_swap::value;
};

template <class _A0, class ..._Allocs>
struct __get_poc_swap<_A0, _Allocs...>
{
    static const bool value =
        allocator_traits<_A0>::propagate_on_container_swap::value ||
        __get_poc_swap<_Allocs...>::value;
};

template <class ..._Allocs> struct __get_is_always_equal;

template <class _A0>
struct __get_is_always_equal<_A0>
{
    static const bool value = allocator_traits<_A0>::is_always_equal::value;
};

template <class _A0, class ..._Allocs>
struct __get_is_always_equal<_A0, _Allocs...>
{
    static const bool value =
        allocator_traits<_A0>::is_always_equal::value &&
        __get_is_always_equal<_Allocs...>::value;
};

template <class ..._Allocs>
class __scoped_allocator_storage;

template <class _OuterAlloc, class... _InnerAllocs>
class __scoped_allocator_storage<_OuterAlloc, _InnerAllocs...>
    : public _OuterAlloc
{
    typedef _OuterAlloc outer_allocator_type;
protected:
    typedef scoped_allocator_adaptor<_InnerAllocs...> inner_allocator_type;

private:
    inner_allocator_type __inner_;

protected:

    _LIBCPP_INLINE_VISIBILITY
    __scoped_allocator_storage() _NOEXCEPT {}

    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, _OuterA2>::value
                      >::type>
        _LIBCPP_INLINE_VISIBILITY
        __scoped_allocator_storage(_OuterA2&& __outerAlloc,
                                   const _InnerAllocs& ...__innerAllocs) _NOEXCEPT
            : outer_allocator_type(_VSTD::forward<_OuterA2>(__outerAlloc)),
              __inner_(__innerAllocs...) {}

    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, const _OuterA2&>::value
                      >::type>
        _LIBCPP_INLINE_VISIBILITY
        __scoped_allocator_storage(
            const __scoped_allocator_storage<_OuterA2, _InnerAllocs...>& __other) _NOEXCEPT
            : outer_allocator_type(__other.outer_allocator()),
              __inner_(__other.inner_allocator()) {}

    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, _OuterA2>::value
                      >::type>
        _LIBCPP_INLINE_VISIBILITY
        __scoped_allocator_storage(
            __scoped_allocator_storage<_OuterA2, _InnerAllocs...>&& __other) _NOEXCEPT
            : outer_allocator_type(_VSTD::move(__other.outer_allocator())),
              __inner_(_VSTD::move(__other.inner_allocator())) {}

    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, _OuterA2>::value
                      >::type>
        _LIBCPP_INLINE_VISIBILITY
        __scoped_allocator_storage(_OuterA2&& __o,
                                   const inner_allocator_type& __i) _NOEXCEPT
            : outer_allocator_type(_VSTD::forward<_OuterA2>(__o)),
              __inner_(__i)
        {
        }

    _LIBCPP_INLINE_VISIBILITY
    inner_allocator_type& inner_allocator() _NOEXCEPT             {return __inner_;}
    _LIBCPP_INLINE_VISIBILITY
    const inner_allocator_type& inner_allocator() const _NOEXCEPT {return __inner_;}

    _LIBCPP_INLINE_VISIBILITY
    outer_allocator_type& outer_allocator() _NOEXCEPT
        {return static_cast<outer_allocator_type&>(*this);}
    _LIBCPP_INLINE_VISIBILITY
    const outer_allocator_type& outer_allocator() const _NOEXCEPT
        {return static_cast<const outer_allocator_type&>(*this);}

    scoped_allocator_adaptor<outer_allocator_type, _InnerAllocs...>
    _LIBCPP_INLINE_VISIBILITY
    select_on_container_copy_construction() const _NOEXCEPT
        {
            return scoped_allocator_adaptor<outer_allocator_type, _InnerAllocs...>
            (
                allocator_traits<outer_allocator_type>::
                    select_on_container_copy_construction(outer_allocator()),
                allocator_traits<inner_allocator_type>::
                    select_on_container_copy_construction(inner_allocator())
            );
        }

    template <class...> friend class __scoped_allocator_storage;
};

template <class _OuterAlloc>
class __scoped_allocator_storage<_OuterAlloc>
    : public _OuterAlloc
{
    typedef _OuterAlloc outer_allocator_type;
protected:
    typedef scoped_allocator_adaptor<_OuterAlloc> inner_allocator_type;

    _LIBCPP_INLINE_VISIBILITY
    __scoped_allocator_storage() _NOEXCEPT {}

    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, _OuterA2>::value
                      >::type>
        _LIBCPP_INLINE_VISIBILITY
        __scoped_allocator_storage(_OuterA2&& __outerAlloc) _NOEXCEPT
            : outer_allocator_type(_VSTD::forward<_OuterA2>(__outerAlloc)) {}

    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, const _OuterA2&>::value
                      >::type>
        _LIBCPP_INLINE_VISIBILITY
        __scoped_allocator_storage(
            const __scoped_allocator_storage<_OuterA2>& __other) _NOEXCEPT
            : outer_allocator_type(__other.outer_allocator()) {}

    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, _OuterA2>::value
                      >::type>
        _LIBCPP_INLINE_VISIBILITY
        __scoped_allocator_storage(
            __scoped_allocator_storage<_OuterA2>&& __other) _NOEXCEPT
            : outer_allocator_type(_VSTD::move(__other.outer_allocator())) {}

    _LIBCPP_INLINE_VISIBILITY
    inner_allocator_type& inner_allocator() _NOEXCEPT
        {return static_cast<inner_allocator_type&>(*this);}
    _LIBCPP_INLINE_VISIBILITY
    const inner_allocator_type& inner_allocator() const _NOEXCEPT
        {return static_cast<const inner_allocator_type&>(*this);}

    _LIBCPP_INLINE_VISIBILITY
    outer_allocator_type& outer_allocator() _NOEXCEPT
        {return static_cast<outer_allocator_type&>(*this);}
    _LIBCPP_INLINE_VISIBILITY
    const outer_allocator_type& outer_allocator() const _NOEXCEPT
        {return static_cast<const outer_allocator_type&>(*this);}

    _LIBCPP_INLINE_VISIBILITY
    scoped_allocator_adaptor<outer_allocator_type>
    select_on_container_copy_construction() const _NOEXCEPT
        {return scoped_allocator_adaptor<outer_allocator_type>(
            allocator_traits<outer_allocator_type>::
                select_on_container_copy_construction(outer_allocator())
        );}

    __scoped_allocator_storage(const outer_allocator_type& __o,
                               const inner_allocator_type& __i) _NOEXCEPT;

    template <class...> friend class __scoped_allocator_storage;
};

// __outermost

template <class _Alloc>
decltype(declval<_Alloc>().outer_allocator(), true_type())
__has_outer_allocator_test(_Alloc&& __a);

template <class _Alloc>
false_type
__has_outer_allocator_test(const volatile _Alloc& __a);

template <class _Alloc>
struct __has_outer_allocator
    : public common_type
             <
                 decltype(__has_outer_allocator_test(declval<_Alloc&>()))
             >::type
{
};

template <class _Alloc, bool = __has_outer_allocator<_Alloc>::value>
struct __outermost
{
    typedef _Alloc type;
    _LIBCPP_INLINE_VISIBILITY
    type& operator()(type& __a) const _NOEXCEPT {return __a;}
};

template <class _Alloc>
struct __outermost<_Alloc, true>
{
    typedef typename remove_reference
                     <
                        decltype(declval<_Alloc>().outer_allocator())
                     >::type                                    _OuterAlloc;
    typedef typename __outermost<_OuterAlloc>::type             type;
    _LIBCPP_INLINE_VISIBILITY
    type& operator()(_Alloc& __a) const _NOEXCEPT
        {return __outermost<_OuterAlloc>()(__a.outer_allocator());}
};

template <class _OuterAlloc, class... _InnerAllocs>
class _LIBCPP_TEMPLATE_VIS scoped_allocator_adaptor<_OuterAlloc, _InnerAllocs...>
    : public __scoped_allocator_storage<_OuterAlloc, _InnerAllocs...>
{
    typedef __scoped_allocator_storage<_OuterAlloc, _InnerAllocs...> base;
    typedef allocator_traits<_OuterAlloc>             _OuterTraits;
public:
    typedef _OuterAlloc                               outer_allocator_type;
    typedef typename base::inner_allocator_type       inner_allocator_type;
    typedef typename _OuterTraits::size_type          size_type;
    typedef typename _OuterTraits::difference_type    difference_type;
    typedef typename _OuterTraits::pointer            pointer;
    typedef typename _OuterTraits::const_pointer      const_pointer;
    typedef typename _OuterTraits::void_pointer       void_pointer;
    typedef typename _OuterTraits::const_void_pointer const_void_pointer;

    typedef integral_constant
            <
                bool,
                __get_poc_copy_assignment<outer_allocator_type,
                                          _InnerAllocs...>::value
            > propagate_on_container_copy_assignment;
    typedef integral_constant
            <
                bool,
                __get_poc_move_assignment<outer_allocator_type,
                                          _InnerAllocs...>::value
            > propagate_on_container_move_assignment;
    typedef integral_constant
            <
                bool,
                __get_poc_swap<outer_allocator_type, _InnerAllocs...>::value
            > propagate_on_container_swap;
    typedef integral_constant
            <
                bool,
                __get_is_always_equal<outer_allocator_type, _InnerAllocs...>::value
            > is_always_equal;

    template <class _Tp>
    struct rebind
    {
        typedef scoped_allocator_adaptor
        <
            typename _OuterTraits::template rebind_alloc<_Tp>, _InnerAllocs...
        > other;
    };

    _LIBCPP_INLINE_VISIBILITY
    scoped_allocator_adaptor() _NOEXCEPT {}
    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, _OuterA2>::value
                      >::type>
        _LIBCPP_INLINE_VISIBILITY
        scoped_allocator_adaptor(_OuterA2&& __outerAlloc,
                                 const _InnerAllocs& ...__innerAllocs) _NOEXCEPT
            : base(_VSTD::forward<_OuterA2>(__outerAlloc), __innerAllocs...) {}
    // scoped_allocator_adaptor(const scoped_allocator_adaptor& __other) = default;
    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, const _OuterA2&>::value
                      >::type>
        _LIBCPP_INLINE_VISIBILITY
        scoped_allocator_adaptor(
            const scoped_allocator_adaptor<_OuterA2, _InnerAllocs...>& __other) _NOEXCEPT
                : base(__other) {}
    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, _OuterA2>::value
                      >::type>
        _LIBCPP_INLINE_VISIBILITY
        scoped_allocator_adaptor(
            scoped_allocator_adaptor<_OuterA2, _InnerAllocs...>&& __other) _NOEXCEPT
                : base(_VSTD::move(__other)) {}

    // scoped_allocator_adaptor& operator=(const scoped_allocator_adaptor&) = default;
    // scoped_allocator_adaptor& operator=(scoped_allocator_adaptor&&) = default;
    // ~scoped_allocator_adaptor() = default;

    _LIBCPP_INLINE_VISIBILITY
    inner_allocator_type& inner_allocator() _NOEXCEPT
        {return base::inner_allocator();}
    _LIBCPP_INLINE_VISIBILITY
    const inner_allocator_type& inner_allocator() const _NOEXCEPT
        {return base::inner_allocator();}

    _LIBCPP_INLINE_VISIBILITY
    outer_allocator_type& outer_allocator() _NOEXCEPT
        {return base::outer_allocator();}
    _LIBCPP_INLINE_VISIBILITY
    const outer_allocator_type& outer_allocator() const _NOEXCEPT
        {return base::outer_allocator();}

    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
    pointer allocate(size_type __n)
        {return allocator_traits<outer_allocator_type>::
            allocate(outer_allocator(), __n);}
    _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY
    pointer allocate(size_type __n, const_void_pointer __hint)
        {return allocator_traits<outer_allocator_type>::
            allocate(outer_allocator(), __n, __hint);}

    _LIBCPP_INLINE_VISIBILITY
    void deallocate(pointer __p, size_type __n) _NOEXCEPT
        {allocator_traits<outer_allocator_type>::
            deallocate(outer_allocator(), __p, __n);}

    _LIBCPP_INLINE_VISIBILITY
    size_type max_size() const
        {return allocator_traits<outer_allocator_type>::max_size(outer_allocator());}

    template <class _Tp, class... _Args>
        _LIBCPP_INLINE_VISIBILITY
        void construct(_Tp* __p, _Args&& ...__args)
            {__construct(__uses_alloc_ctor<_Tp, inner_allocator_type&, _Args...>(),
                         __p, _VSTD::forward<_Args>(__args)...);}

    template <class _T1, class _T2, class... _Args1, class... _Args2>
    void construct(pair<_T1, _T2>* __p, piecewise_construct_t,
                       tuple<_Args1...> __x, tuple<_Args2...> __y)
    {
        typedef __outermost<outer_allocator_type> _OM;
        allocator_traits<typename _OM::type>::construct(
            _OM()(outer_allocator()), __p, piecewise_construct
          , __transform_tuple(
              typename __uses_alloc_ctor<
                  _T1, inner_allocator_type&, _Args1...
              >::type()
            , _VSTD::move(__x)
            , typename __make_tuple_indices<sizeof...(_Args1)>::type{}
          )
          , __transform_tuple(
              typename __uses_alloc_ctor<
                  _T2, inner_allocator_type&, _Args2...
              >::type()
            , _VSTD::move(__y)
            , typename __make_tuple_indices<sizeof...(_Args2)>::type{}
          )
        );
    }

    template <class _T1, class _T2>
    void construct(pair<_T1, _T2>* __p)
    { construct(__p, piecewise_construct, tuple<>{}, tuple<>{}); }

    template <class _T1, class _T2, class _Up, class _Vp>
    void construct(pair<_T1, _T2>* __p, _Up&& __x, _Vp&& __y) {
        construct(__p, piecewise_construct,
                  _VSTD::forward_as_tuple(_VSTD::forward<_Up>(__x)),
                  _VSTD::forward_as_tuple(_VSTD::forward<_Vp>(__y)));
    }

    template <class _T1, class _T2, class _Up, class _Vp>
    void construct(pair<_T1, _T2>* __p, const pair<_Up, _Vp>& __x) {
        construct(__p, piecewise_construct,
                  _VSTD::forward_as_tuple(__x.first),
                  _VSTD::forward_as_tuple(__x.second));
    }

    template <class _T1, class _T2, class _Up, class _Vp>
    void construct(pair<_T1, _T2>* __p, pair<_Up, _Vp>&& __x) {
        construct(__p, piecewise_construct,
                  _VSTD::forward_as_tuple(_VSTD::forward<_Up>(__x.first)),
                  _VSTD::forward_as_tuple(_VSTD::forward<_Vp>(__x.second)));
    }

    template <class _Tp>
        _LIBCPP_INLINE_VISIBILITY
        void destroy(_Tp* __p)
            {
                typedef __outermost<outer_allocator_type> _OM;
                allocator_traits<typename _OM::type>::
                                         destroy(_OM()(outer_allocator()), __p);
            }

    _LIBCPP_INLINE_VISIBILITY
    scoped_allocator_adaptor select_on_container_copy_construction() const _NOEXCEPT
        {return base::select_on_container_copy_construction();}

private:


    template <class _OuterA2,
              class = typename enable_if<
                        is_constructible<outer_allocator_type, _OuterA2>::value
                      >::type>
    _LIBCPP_INLINE_VISIBILITY
    scoped_allocator_adaptor(_OuterA2&& __o,
                             const inner_allocator_type& __i) _NOEXCEPT
        : base(_VSTD::forward<_OuterA2>(__o), __i) {}

    template <class _Tp, class... _Args>
        _LIBCPP_INLINE_VISIBILITY
        void __construct(integral_constant<int, 0>, _Tp* __p, _Args&& ...__args)
            {
                typedef __outermost<outer_allocator_type> _OM;
                allocator_traits<typename _OM::type>::construct
                (
                    _OM()(outer_allocator()),
                    __p,
                    _VSTD::forward<_Args>(__args)...
                );
            }

    template <class _Tp, class... _Args>
        _LIBCPP_INLINE_VISIBILITY
        void __construct(integral_constant<int, 1>, _Tp* __p, _Args&& ...__args)
            {
                typedef __outermost<outer_allocator_type> _OM;
                allocator_traits<typename _OM::type>::construct
                (
                    _OM()(outer_allocator()),
                    __p, allocator_arg, inner_allocator(),
                    _VSTD::forward<_Args>(__args)...
                );
            }

    template <class _Tp, class... _Args>
        _LIBCPP_INLINE_VISIBILITY
        void __construct(integral_constant<int, 2>, _Tp* __p, _Args&& ...__args)
            {
                typedef __outermost<outer_allocator_type> _OM;
                allocator_traits<typename _OM::type>::construct
                (
                    _OM()(outer_allocator()),
                    __p,
                    _VSTD::forward<_Args>(__args)...,
                    inner_allocator()
                );
            }

    template <class ..._Args, size_t ..._Idx>
    _LIBCPP_INLINE_VISIBILITY
    tuple<_Args&&...>
    __transform_tuple(integral_constant<int, 0>, tuple<_Args...>&& __t,
                      __tuple_indices<_Idx...>)
    {
        return _VSTD::forward_as_tuple(_VSTD::get<_Idx>(_VSTD::move(__t))...);
    }

    template <class ..._Args, size_t ..._Idx>
    _LIBCPP_INLINE_VISIBILITY
    tuple<allocator_arg_t, inner_allocator_type&, _Args&&...>
    __transform_tuple(integral_constant<int, 1>, tuple<_Args...> && __t,
                      __tuple_indices<_Idx...>)
    {
        using _Tup = tuple<allocator_arg_t, inner_allocator_type&, _Args&&...>;
        return _Tup(allocator_arg, inner_allocator(),
                    _VSTD::get<_Idx>(_VSTD::move(__t))...);
    }

    template <class ..._Args, size_t ..._Idx>
    _LIBCPP_INLINE_VISIBILITY
    tuple<_Args&&..., inner_allocator_type&>
    __transform_tuple(integral_constant<int, 2>, tuple<_Args...> && __t,
                      __tuple_indices<_Idx...>)
    {
        using _Tup = tuple<_Args&&..., inner_allocator_type&>;
        return _Tup(_VSTD::get<_Idx>(_VSTD::move(__t))..., inner_allocator());
    }

    template <class...> friend class __scoped_allocator_storage;
};

#if _LIBCPP_STD_VER > 14
template<class _OuterAlloc, class... _InnerAllocs>
    scoped_allocator_adaptor(_OuterAlloc, _InnerAllocs...)
        -> scoped_allocator_adaptor<_OuterAlloc, _InnerAllocs...>;
#endif

template <class _OuterA1, class _OuterA2>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator==(const scoped_allocator_adaptor<_OuterA1>& __a,
           const scoped_allocator_adaptor<_OuterA2>& __b) _NOEXCEPT
{
    return __a.outer_allocator() == __b.outer_allocator();
}

template <class _OuterA1, class _OuterA2, class _InnerA0, class... _InnerAllocs>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator==(const scoped_allocator_adaptor<_OuterA1, _InnerA0, _InnerAllocs...>& __a,
           const scoped_allocator_adaptor<_OuterA2, _InnerA0, _InnerAllocs...>& __b) _NOEXCEPT
{
    return __a.outer_allocator() == __b.outer_allocator() &&
           __a.inner_allocator() == __b.inner_allocator();
}

template <class _OuterA1, class _OuterA2, class... _InnerAllocs>
inline _LIBCPP_INLINE_VISIBILITY
bool
operator!=(const scoped_allocator_adaptor<_OuterA1, _InnerAllocs...>& __a,
           const scoped_allocator_adaptor<_OuterA2, _InnerAllocs...>& __b) _NOEXCEPT
{
    return !(__a == __b);
}

#endif // !defined(_LIBCPP_CXX03_LANG)

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP_SCOPED_ALLOCATOR