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 37 _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 45 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp& get() { return *__addr(); } 46 47 template <class... _Args> 48 _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 53 _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