commit 25c8ce6e2798b959e007ab0588aa39ba47d93d61
author Christopher Di Bella <cjdb@google.com> Mon Feb 08 05:08:25 2021 +0000
committer Copybara-Service <copybara-worker@google.com> Wed Feb 10 11:40:26 2021 -0800
tree 0b7314986c30af12278ae5004246b0361a5b0320
parent 2050d99d59b7c7cf09411a8638b0e00e7b01712d

[libcxx] adds concepts `std::invocable` and `std::regular_invocable`

Implements parts of:
    - P0898R3 Standard Library Concepts
    - P1754 Rename concepts to standard_case for C++20, while we still can

Differential Revision: https://reviews.llvm.org/D96235

GitOrigin-RevId: 17db24a7a8f23eb5adb24f36b9d51bb7cc5ae564

include/concepts

diff --git a/include/concepts b/include/concepts
index 7c42dc8..478b865 100644
--- a/include/concepts
+++ b/include/concepts
@@ -135,7 +135,9 @@
 */
 
 #include <__config>
+#include <functional>
 #include <type_traits>
+#include <utility>
 #include <version>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -216,6 +218,16 @@
   constructible_from<_Tp, const _Tp&> && convertible_to<const _Tp&, _Tp> &&
   constructible_from<_Tp, const _Tp> && convertible_to<const _Tp, _Tp>;
 
+// [concept.invocable]
+template<class _Fn, class... _Args>
+concept invocable = requires(_Fn&& __fn, _Args&&... __args) {
+  _VSTD::invoke(_VSTD::forward<_Fn>(__fn), _VSTD::forward<_Args>(__args)...); // not required to be equality preserving
+};
+
+// [concept.regular.invocable]
+template<class _Fn, class... _Args>
+concept regular_invocable = invocable<_Fn, _Args...>;
+
 #endif //_LIBCPP_STD_VER > 17 && defined(__cpp_concepts) && __cpp_concepts >= 201811L
 
 _LIBCPP_END_NAMESPACE_STD