add is_invocable_r

README.md

@@ -34,18 +34,26 @@
 
 ### `invoke_hpp::invoke(F&& f, Args&&... args)`
 
-Analog of [std::invoke](https://en.cppreference.com/w/cpp/utility/functional/invoke) from C++17
+Analog of [`std::invoke`](https://en.cppreference.com/w/cpp/utility/functional/invoke) from C++17
 
 ### `invoke_hpp::invoke_result<F, Args...>`
 
-Analog of [std::invoke_result](https://en.cppreference.com/w/cpp/types/result_of) from C++17
+Analog of [`std::invoke_result`](https://en.cppreference.com/w/cpp/types/result_of) from C++17
+
+### `invoke_hpp::invoke_result_t<F, Args...>`
+
+Analog of [`std::invoke_result_t`](https://en.cppreference.com/w/cpp/types/result_of) from C++17
 
 ### `invoke_hpp::is_invocable<F, Args...>`
 
-Analog of [std::is_invocable](https://en.cppreference.com/w/cpp/types/is_invocable) from C++17
+Analog of [`std::is_invocable`](https://en.cppreference.com/w/cpp/types/is_invocable) from C++17
+
+### `invoke_hpp::is_invocable_r<R, F, Args...>`
+
+Analog of [`std::is_invocable_r`](https://en.cppreference.com/w/cpp/types/is_invocable) from C++17
 
 ### `invoke_hpp::apply(F&& f, Tuple&& args)`
 
-Analog of [std::apply](https://en.cppreference.com/w/cpp/utility/apply) from C++17
+Analog of [`std::apply`](https://en.cppreference.com/w/cpp/utility/apply) from C++17
 
 ## [License (MIT)](./LICENSE.md)

invoke.hpp

@@ -191,20 +191,26 @@ namespace invoke_hpp
 {
     namespace impl
     {
-        struct is_invocable_impl_tag {};
+        struct is_invocable_r_impl_tag {};
 
-        template < typename Void, typename F, typename... Args >
+        template < typename Void, typename R, typename F, typename... Args >
-        struct is_invocable_impl
+        struct is_invocable_r_impl
         : std::false_type {};
 
-        template < typename F, typename... Args >
+        template < typename R, typename F, typename... Args >
-        struct is_invocable_impl<void_t<is_invocable_impl_tag, invoke_result_t<F, Args...>>, F, Args...>
+        struct is_invocable_r_impl<void_t<is_invocable_r_impl_tag, invoke_result_t<F, Args...>>, R, F, Args...>
-        : std::true_type {};
+        : std::conditional_t<
+            std::is_void<R>::value,
+            std::true_type,
+            std::is_convertible<invoke_result_t<F, Args...>, R>> {};
     }
 
+    template < typename R, typename F, typename... Args >
+    struct is_invocable_r
+    : impl::is_invocable_r_impl<void, R, F, Args...> {};
+
     template < typename F, typename... Args >
-    struct is_invocable
+    using is_invocable = is_invocable_r<void, F, Args...>;
-    : impl::is_invocable_impl<void, F, Args...> {};
 }
 
 //

tests.cpp

@@ -298,6 +298,166 @@ TEST_CASE("is_invocable"){
     }
 }
 
+TEST_CASE("is_invocable_r"){
+    SECTION("is_invocable_r_functions"){
+        static_assert(
+            inv::is_invocable_r<void, decltype(simple_static_function)>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<int, decltype(simple_static_function_r)>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<void, decltype(simple_static_function_r)>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<const int&, decltype(simple_static_function_r_with_arg), const int&>::value,
+            "unit test fail");
+    }
+    SECTION("is_not_invocable_r_functions"){
+        static_assert(
+            !inv::is_invocable_r<void, decltype(simple_static_function), int>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<int, decltype(simple_static_function_r), obj_t>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<const int&, decltype(simple_static_function_r_with_arg), const obj2_t&>::value,
+            "unit test fail");
+
+        static_assert(
+            !inv::is_invocable_r<int, decltype(simple_static_function)>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<int*, decltype(simple_static_function_r)>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<obj_t, decltype(simple_static_function_r_with_arg), const int&>::value,
+            "unit test fail");
+    }
+    SECTION("is_invocable_r_members"){
+        static_assert(
+            inv::is_invocable_r<void, decltype(&obj_t::member), obj_t>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<void, decltype(&obj_t::member), obj_t*>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<void, decltype(&obj_t::member), std::reference_wrapper<obj_t>>::value,
+            "unit test fail");
+
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::member_r), obj_t>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::member_r), obj_t*>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::member_r), std::reference_wrapper<obj_t>>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<void, decltype(&obj_t::member_r), std::reference_wrapper<obj_t>>::value,
+            "unit test fail");
+
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::member_r_with_arg), obj_t, int>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::member_r_with_arg), obj_t*, int>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::member_r_with_arg), std::reference_wrapper<obj_t>, int>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<void, decltype(&obj_t::member_r_with_arg), std::reference_wrapper<obj_t>, int>::value,
+            "unit test fail");
+    }
+    SECTION("is_not_invocable_r_members"){
+        static_assert(
+            !inv::is_invocable_r<int, decltype(&obj_t::member), obj_t>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<int*, decltype(&obj_t::member), obj_t*>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<obj_t, decltype(&obj_t::member), std::reference_wrapper<obj_t>>::value,
+            "unit test fail");
+
+        static_assert(
+            !inv::is_invocable_r<obj_t, decltype(&obj_t::member_r), obj_t>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<int*, decltype(&obj_t::member_r), obj_t*>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<int, decltype(&obj_t::member_r), std::reference_wrapper<obj2_t>>::value,
+            "unit test fail");
+
+        static_assert(
+            !inv::is_invocable_r<obj_t, decltype(&obj_t::member_r_with_arg), obj_t, int>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<int*, decltype(&obj_t::member_r_with_arg), obj_t*, int>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<int, decltype(&obj_t::member_r_with_arg), std::reference_wrapper<obj_t>, obj2_t>::value,
+            "unit test fail");
+    }
+    SECTION("is_invocable_r_objects"){
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::value), obj_t>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::value), obj_t*>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::value), std::reference_wrapper<obj_t>>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<void, decltype(&obj_t::value), std::reference_wrapper<obj_t>>::value,
+            "unit test fail");
+
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::value_c), obj_t>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::value_c), obj_t*>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<int, decltype(&obj_t::value_c), std::reference_wrapper<obj_t>>::value,
+            "unit test fail");
+        static_assert(
+            inv::is_invocable_r<void, decltype(&obj_t::value_c), std::reference_wrapper<obj_t>>::value,
+            "unit test fail");
+    }
+    SECTION("is_not_invocable_r_objects"){
+        static_assert(
+            !inv::is_invocable_r<obj_t, decltype(&obj_t::value), obj_t>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<int*, decltype(&obj_t::value), obj_t*>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<int, decltype(&obj_t::value), std::reference_wrapper<obj_t>, obj2_t>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<void, decltype(&obj_t::value), std::reference_wrapper<obj_t>, obj2_t>::value,
+            "unit test fail");
+
+        static_assert(
+            !inv::is_invocable_r<obj_t, decltype(&obj_t::value_c), obj_t>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<int*, decltype(&obj_t::value_c), obj_t*>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<obj2_t, decltype(&obj_t::value_c), std::reference_wrapper<obj_t>>::value,
+            "unit test fail");
+        static_assert(
+            !inv::is_invocable_r<void, decltype(&obj_t::value_c), std::reference_wrapper<obj_t**>>::value,
+            "unit test fail");
+    }
+}
+
 TEST_CASE("apply"){
     SECTION("apply_functions"){
         inv::apply(simple_static_function, std::make_tuple());