llvm-project/libcxx/include/__memory/allocator_arg_t.h

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C++

// -*- 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___FUNCTIONAL_ALLOCATOR_ARG_T_H
#define _LIBCPP___FUNCTIONAL_ALLOCATOR_ARG_T_H
#include <__config>
#include <__memory/uses_allocator.h>
#include <__utility/forward.h>
#include <type_traits>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
# pragma GCC system_header
#endif
_LIBCPP_BEGIN_NAMESPACE_STD
struct _LIBCPP_TEMPLATE_VIS allocator_arg_t { explicit allocator_arg_t() = default; };
#if defined(_LIBCPP_CXX03_LANG) || defined(_LIBCPP_BUILDING_LIBRARY)
extern _LIBCPP_EXPORTED_FROM_ABI const allocator_arg_t allocator_arg;
#else
/* inline */ constexpr allocator_arg_t allocator_arg = allocator_arg_t();
#endif
#ifndef _LIBCPP_CXX03_LANG
// allocator construction
template <class _Tp, class _Alloc, class ..._Args>
struct __uses_alloc_ctor_imp
{
typedef _LIBCPP_NODEBUG __uncvref_t<_Alloc> _RawAlloc;
static const bool __ua = uses_allocator<_Tp, _RawAlloc>::value;
static const bool __ic =
is_constructible<_Tp, allocator_arg_t, _Alloc, _Args...>::value;
static const int value = __ua ? 2 - __ic : 0;
};
template <class _Tp, class _Alloc, class ..._Args>
struct __uses_alloc_ctor
: integral_constant<int, __uses_alloc_ctor_imp<_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);
}
#endif // _LIBCPP_CXX03_LANG
_LIBCPP_END_NAMESPACE_STD
#endif // _LIBCPP___FUNCTIONAL_ALLOCATOR_ARG_T_H