// -*- 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_EXPERIMENTAL___MEMORY
#define _LIBCPP_EXPERIMENTAL___MEMORY

#include <__memory/allocator_arg_t.h>
#include <__memory/uses_allocator.h>
#include <experimental/__config>
#include <experimental/utility> // for erased_type
#include <type_traits>

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

_LIBCPP_BEGIN_NAMESPACE_LFTS

template <
    class _Tp, class _Alloc
  , bool = uses_allocator<_Tp, _Alloc>::value
  , bool = __has_allocator_type<_Tp>::value
  >
struct __lfts_uses_allocator : public false_type {};

template <class _Tp, class _Alloc>
struct __lfts_uses_allocator<_Tp, _Alloc, false, false> : public false_type {};

template <class _Tp, class _Alloc, bool HasAlloc>
struct __lfts_uses_allocator<_Tp, _Alloc, true, HasAlloc> : public true_type {};

template <class _Tp, class _Alloc>
struct __lfts_uses_allocator<_Tp, _Alloc, false, true>
  : public integral_constant<bool
    , is_convertible<_Alloc, typename _Tp::allocator_type>::value
      || is_same<erased_type, typename _Tp::allocator_type>::value
    >
{};

template <bool _UsesAlloc, class _Tp, class _Alloc, class ..._Args>
struct __lfts_uses_alloc_ctor_imp
{
    static const int value = 0;
};

template <class _Tp, class _Alloc, class ..._Args>
struct __lfts_uses_alloc_ctor_imp<true, _Tp, _Alloc, _Args...>
{
    static const bool __ic_first
        = is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value;

    static const bool __ic_second =
        __conditional_t<
            __ic_first,
            false_type,
            is_constructible<_Tp, _Args..., _Alloc>
        >::value;

    static_assert(__ic_first || __ic_second,
                  "Request for uses allocator construction is ill-formed");

    static const int value = __ic_first ? 1 : 2;
};

template <class _Tp, class _Alloc, class ..._Args>
struct __lfts_uses_alloc_ctor
  : integral_constant<int,
        __lfts_uses_alloc_ctor_imp<
            __lfts_uses_allocator<_Tp, _Alloc>::value
          , _Tp, _Alloc, _Args...
        >::value
    >
{};

template <class _Tp, class _Allocator, class... _Args>
inline _LIBCPP_INLINE_VISIBILITY
void __user_alloc_construct_impl (integral_constant<int, 0>, _Tp *__storage, const _Allocator &, _Args &&... __args )
{
    new (__storage) _Tp (_VSTD::forward<_Args>(__args)...);
}

// FIXME: This should have a version which takes a non-const alloc.
template <class _Tp, class _Allocator, class... _Args>
inline _LIBCPP_INLINE_VISIBILITY
void __user_alloc_construct_impl (integral_constant<int, 1>, _Tp *__storage, const _Allocator &__a, _Args &&... __args )
{
    new (__storage) _Tp (allocator_arg, __a, _VSTD::forward<_Args>(__args)...);
}

// FIXME: This should have a version which takes a non-const alloc.
template <class _Tp, class _Allocator, class... _Args>
inline _LIBCPP_INLINE_VISIBILITY
void __user_alloc_construct_impl (integral_constant<int, 2>, _Tp *__storage, const _Allocator &__a, _Args &&... __args )
{
    new (__storage) _Tp (_VSTD::forward<_Args>(__args)..., __a);
}

template <class _Tp, class _Alloc, class ..._Args>
inline _LIBCPP_INLINE_VISIBILITY
void __lfts_user_alloc_construct(
    _Tp * __store, const _Alloc & __a, _Args &&... __args)
{
    ::std::experimental::fundamentals_v1::__user_alloc_construct_impl(
        typename __lfts_uses_alloc_ctor<_Tp, _Alloc, _Args...>::type()
       , __store, __a, _VSTD::forward<_Args>(__args)...
       );
}

_LIBCPP_END_NAMESPACE_LFTS

#endif /* _LIBCPP_EXPERIMENTAL___MEMORY */
