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 
16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17 #  pragma GCC system_header
18 #endif
19 
20 _LIBCPP_BEGIN_NAMESPACE_STD
21 
22 #if _LIBCPP_STD_VER >= 20
23 
24 // [concept.invocable]
25 
26 template <class _Fn, class... _Args>
27 concept invocable = requires(_Fn&& __fn, _Args&&... __args) {
28   std::invoke(std::forward<_Fn>(__fn), std::forward<_Args>(__args)...); // not required to be equality preserving
29 };
30 
31 // [concept.regular.invocable]
32 
33 template <class _Fn, class... _Args>
34 concept regular_invocable = invocable<_Fn, _Args...>;
35 
36 #endif // _LIBCPP_STD_VER >= 20
37 
38 _LIBCPP_END_NAMESPACE_STD
39 
40 #endif // _LIBCPP___CONCEPTS_INVOCABLE_H
41