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___TYPE_TRAITS_UNWRAP_REF_H 10 #define _LIBCPP___TYPE_TRAITS_UNWRAP_REF_H 11 12 #include <__config> 13 #include <__type_traits/decay.h> 14 15 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 16 # pragma GCC system_header 17 #endif 18 19 _LIBCPP_BEGIN_NAMESPACE_STD 20 21 template <class _Tp> 22 struct __unwrap_reference { 23 typedef _LIBCPP_NODEBUG _Tp type; 24 }; 25 26 template <class _Tp> 27 class reference_wrapper; 28 29 template <class _Tp> 30 struct __unwrap_reference<reference_wrapper<_Tp> > { 31 typedef _LIBCPP_NODEBUG _Tp& type; 32 }; 33 34 template <class _Tp> 35 struct decay; 36 37 #if _LIBCPP_STD_VER >= 20 38 template <class _Tp> 39 struct unwrap_reference : __unwrap_reference<_Tp> {}; 40 41 template <class _Tp> 42 using unwrap_reference_t = typename unwrap_reference<_Tp>::type; 43 44 template <class _Tp> 45 struct unwrap_ref_decay : unwrap_reference<__decay_t<_Tp> > {}; 46 47 template <class _Tp> 48 using unwrap_ref_decay_t = typename unwrap_ref_decay<_Tp>::type; 49 #endif // _LIBCPP_STD_VER >= 20 50 51 template <class _Tp> 52 struct __unwrap_ref_decay 53 #if _LIBCPP_STD_VER >= 20 54 : unwrap_ref_decay<_Tp> 55 #else 56 : __unwrap_reference<__decay_t<_Tp> > 57 #endif 58 { 59 }; 60 61 _LIBCPP_END_NAMESPACE_STD 62 63 #endif // _LIBCPP___TYPE_TRAITS_UNWRAP_REF_H 64