xref: /freebsd/contrib/llvm-project/libcxx/include/__concepts/invocable.h (revision e6bfd18d21b225af6a0ed67ceeaf1293b7b9eba5)
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___CONCEPTS_INVOCABLE_H
10 #define _LIBCPP___CONCEPTS_INVOCABLE_H
11 
12 #include <__config>
13 #include <__functional/invoke.h>
14 #include <__utility/forward.h>
15 #include <type_traits>
16 
17 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
18 #  pragma GCC system_header
19 #endif
20 
21 _LIBCPP_BEGIN_NAMESPACE_STD
22 
23 #if _LIBCPP_STD_VER > 17
24 
25 // [concept.invocable]
26 
27 template<class _Fn, class... _Args>
28 concept invocable = requires(_Fn&& __fn, _Args&&... __args) {
29   _VSTD::invoke(_VSTD::forward<_Fn>(__fn), _VSTD::forward<_Args>(__args)...); // not required to be equality preserving
30 };
31 
32 // [concept.regular.invocable]
33 
34 template<class _Fn, class... _Args>
35 concept regular_invocable = invocable<_Fn, _Args...>;
36 
37 #endif // _LIBCPP_STD_VER > 17
38 
39 _LIBCPP_END_NAMESPACE_STD
40 
41 #endif // _LIBCPP___CONCEPTS_INVOCABLE_H
42