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 
24 template <class _Tp, class _Alloc>
25 struct __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 {
32     _Tp __v;
33   };
34 #endif
35   _Alloc& __a;
36 
__addr__temp_value37   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp* __addr() {
38 #ifdef _LIBCPP_CXX03_LANG
39     return reinterpret_cast<_Tp*>(std::addressof(__v));
40 #else
41     return std::addressof(__v);
42 #endif
43   }
44 
get__temp_value45   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& get() { return *__addr(); }
46 
47   template <class... _Args>
__temp_value__temp_value48   _LIBCPP_HIDE_FROM_ABI _LIBCPP_NO_CFI _LIBCPP_CONSTEXPR_SINCE_CXX20 __temp_value(_Alloc& __alloc, _Args&&... __args)
49       : __a(__alloc) {
50     _Traits::construct(__a, __addr(), std::forward<_Args>(__args)...);
51   }
52 
~__temp_value__temp_value53   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 ~__temp_value() { _Traits::destroy(__a, __addr()); }
54 };
55 
56 _LIBCPP_END_NAMESPACE_STD
57 
58 #endif // _LIBCPP___MEMORY_TEMP_VALUE_H
59