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