__cxx03/__concepts/invocable.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___CXX03___CONCEPTS_INVOCABLE_H
0010 #define _LIBCPP___CXX03___CONCEPTS_INVOCABLE_H
0011
0012 #include <__cxx03/__config>
0013 #include <__cxx03/__functional/invoke.h>
0014 #include <__cxx03/__utility/forward.h>
0015
0016 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0017 #  pragma GCC system_header
0018 #endif
0019
0020 _LIBCPP_BEGIN_NAMESPACE_STD
0021
0022 #if _LIBCPP_STD_VER >= 20
0023
0024 // [concept.invocable]
0025
0026 template <class _Fn, class... _Args>
0027 concept invocable = requires(_Fn&& __fn, _Args&&... __args) {
0028   std::invoke(std::forward<_Fn>(__fn), std::forward<_Args>(__args)...); // not required to be equality preserving
0029 };
0030
0031 // [concept.regular.invocable]
0032
0033 template <class _Fn, class... _Args>
0034 concept regular_invocable = invocable<_Fn, _Args...>;
0035
0036 #endif // _LIBCPP_STD_VER >= 20
0037
0038 _LIBCPP_END_NAMESPACE_STD
0039
0040 #endif // _LIBCPP___CXX03___CONCEPTS_INVOCABLE_H