✨ add is_function trait

include/zll/meta/traits/is_function.hpp

@@ -0,0 +1,26 @@
+#ifndef ZLL_META_TRAITS_ISFUNCTION_HPP
+#define ZLL_META_TRAITS_ISFUNCTION_HPP
+
+#include "zll/meta/integral_constant.hpp"
+#include "zll/meta/traits/is_const.hpp"
+#include "zll/meta/traits/is_reference.hpp"
+
+namespace zll {
+namespace meta {
+
+namespace detail {
+
+template <typename T>
+struct is_function_helper {
+    static const bool value = !(zll::meta::is_const<const T>::value) && !(zll::meta::is_reference<T>::value);
+};
+
+}  // namespace detail
+
+template <typename T>
+struct is_function : zll::meta::bool_constant<detail::is_function_helper<T>::value> {};
+
+}  // namespace meta
+}  // namespace zll
+
+#endif  //  ZLL_META_TRAITS_ISFUNCTION_HPP

tests/unit_tests/meson.build

@@ -12,6 +12,7 @@ unit_tests_srcs = [
     'meta/traits/is_const_tests.cpp',
     'meta/traits/is_enum_tests.cpp',
     'meta/traits/is_floating_point_tests.cpp',
+    'meta/traits/is_function_tests.cpp',
     'meta/traits/is_integral_tests.cpp',
     'meta/traits/is_member_pointer_tests.cpp',
     'meta/traits/is_object_tests.cpp',

tests/unit_tests/meta/traits/is_function_tests.cpp

@@ -0,0 +1,31 @@
+#include <zll/meta/traits/is_function.hpp>
+#include <zll/utils/typeof_macro.hpp>
+
+#include <utest.h>
+
+struct test_struct {
+    int fun() const;
+};
+
+int test_function();
+
+template <typename T>
+struct test_trait {};
+template <typename T, typename U>
+struct test_trait<U T::*> {
+    typedef U member_type;
+};
+
+UTEST(meta_traits_is_function, is_function) {
+    ASSERT_TRUE((zll::meta::is_function<int(int)>::value));
+    ASSERT_TRUE((zll::meta::is_function<ZLL_TYPE_OF(test_function)>::value));
+
+    typedef test_trait<ZLL_TYPE_OF(&test_struct::fun)>::member_type fun_type;
+    ASSERT_TRUE((zll::meta::is_function<fun_type>::value));
+}
+
+UTEST(meta_traits_is_function, is_not_function) {
+    ASSERT_FALSE((zll::meta::is_function<int>::value));
+    ASSERT_FALSE((zll::meta::is_function<test_struct>::value));
+}
+