xref: /freebsd/contrib/llvm-project/libcxx/include/__type_traits/unwrap_ref.h (revision 0fca6ea1d4eea4c934cfff25ac9ee8ad6fe95583)
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 <__fwd/functional.h>
14 #include <__type_traits/decay.h>
15 
16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17 #  pragma GCC system_header
18 #endif
19 
20 _LIBCPP_BEGIN_NAMESPACE_STD
21 
22 template <class _Tp>
23 struct __unwrap_reference {
24   typedef _LIBCPP_NODEBUG _Tp type;
25 };
26 
27 template <class _Tp>
28 struct __unwrap_reference<reference_wrapper<_Tp> > {
29   typedef _LIBCPP_NODEBUG _Tp& type;
30 };
31 
32 #if _LIBCPP_STD_VER >= 20
33 template <class _Tp>
34 struct unwrap_reference : __unwrap_reference<_Tp> {};
35 
36 template <class _Tp>
37 using unwrap_reference_t = typename unwrap_reference<_Tp>::type;
38 
39 template <class _Tp>
40 struct unwrap_ref_decay : unwrap_reference<__decay_t<_Tp> > {};
41 
42 template <class _Tp>
43 using unwrap_ref_decay_t = typename unwrap_ref_decay<_Tp>::type;
44 #endif // _LIBCPP_STD_VER >= 20
45 
46 template <class _Tp>
47 struct __unwrap_ref_decay
48 #if _LIBCPP_STD_VER >= 20
49     : unwrap_ref_decay<_Tp>
50 #else
51     : __unwrap_reference<__decay_t<_Tp> >
52 #endif
53 {
54 };
55 
56 _LIBCPP_END_NAMESPACE_STD
57 
58 #endif // _LIBCPP___TYPE_TRAITS_UNWRAP_REF_H
59