1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#ifndef _LIBCPP___MEMORY_TEMP_VALUE_H
10#define _LIBCPP___MEMORY_TEMP_VALUE_H
11
12#include <__config>
13#include <__memory/addressof.h>
14#include <__memory/allocator_traits.h>
15#include <__type_traits/aligned_storage.h>
16#include <__utility/forward.h>
17
18#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19#  pragma GCC system_header
20#endif
21
22_LIBCPP_BEGIN_NAMESPACE_STD
23
24template <class _Tp, class _Alloc>
25struct __temp_value {
26    typedef allocator_traits<_Alloc> _Traits;
27
28#ifdef _LIBCPP_CXX03_LANG
29    typename aligned_storage<sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)>::type __v;
30#else
31    union { _Tp __v; };
32#endif
33    _Alloc &__a;
34
35    _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp *__addr() {
36#ifdef _LIBCPP_CXX03_LANG
37        return reinterpret_cast<_Tp*>(std::addressof(__v));
38#else
39        return std::addressof(__v);
40#endif
41    }
42
43    _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp &   get() { return *__addr(); }
44
45    template<class... _Args>
46    _LIBCPP_NO_CFI
47    _LIBCPP_CONSTEXPR_SINCE_CXX20 __temp_value(_Alloc &__alloc, _Args&& ... __args) : __a(__alloc) {
48      _Traits::construct(__a, __addr(), std::forward<_Args>(__args)...);
49    }
50
51    _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__temp_value() { _Traits::destroy(__a, __addr()); }
52};
53
54_LIBCPP_END_NAMESPACE_STD
55
56#endif // _LIBCPP___MEMORY_TEMP_VALUE_H
57