From 38ab48b1882f36ed7eb7e50c4fb46ce5d376fbc3 Mon Sep 17 00:00:00 2001
From: Steven Le Rouzic <steven.lerouzic@gmail.com>
Date: Wed, 26 Feb 2025 20:01:45 +0100
Subject: Fix some deducing-this & functional stuff, add invocable concept

---
 asl/base/defer.hpp            |  6 ++----
 asl/base/functional.hpp       | 19 ++++++++++++++++---
 asl/base/functional_tests.cpp | 24 +++++++++++++++++++-----
 3 files changed, 37 insertions(+), 12 deletions(-)

(limited to 'asl/base')

diff --git a/asl/base/defer.hpp b/asl/base/defer.hpp
index b6d52af..e881d8a 100644
--- a/asl/base/defer.hpp
+++ b/asl/base/defer.hpp
@@ -6,8 +6,7 @@
 namespace asl
 {
 
-// @Todo Add invokable check
-template<typename Callback>
+template<invocable Callback>
 class DeferCallback
 {
     Callback m_callback;
@@ -36,8 +35,7 @@ public:
 
 struct DeferFactory
 {
-    // @Todo Add invokable check
-    template<typename Callback>
+    template<invocable Callback>
     DeferCallback<Callback> operator<<(Callback&& callback) const
     {
         return DeferCallback<Callback>(ASL_FWD(callback));
diff --git a/asl/base/functional.hpp b/asl/base/functional.hpp
index d820bce..b4b5312 100644
--- a/asl/base/functional.hpp
+++ b/asl/base/functional.hpp
@@ -7,6 +7,7 @@ namespace asl {
 
 template<typename... Args, typename C>
 constexpr auto invoke(is_func auto C::* f, auto&& self, Args&&... args)
+    -> decltype((self.*f)(ASL_FWD(args)...))
     requires requires {
         (self.*f)(ASL_FWD(args)...);
     }
@@ -16,6 +17,7 @@ constexpr auto invoke(is_func auto C::* f, auto&& self, Args&&... args)
 
 template<typename... Args, typename C>
 constexpr auto invoke(is_func auto C::* f, auto* self, Args&&... args)
+    -> decltype((self->*f)(ASL_FWD(args)...))
     requires requires {
         (self->*f)(ASL_FWD(args)...);
     }
@@ -25,6 +27,7 @@ constexpr auto invoke(is_func auto C::* f, auto* self, Args&&... args)
 
 template<typename... Args, typename C>
 constexpr auto invoke(is_object auto C::* m, auto&& self, Args&&...)
+    -> decltype(self.*m)
     requires (
         sizeof...(Args) == 0 &&
         requires { self.*m; }
@@ -35,6 +38,7 @@ constexpr auto invoke(is_object auto C::* m, auto&& self, Args&&...)
 
 template<typename... Args, typename C>
 constexpr auto invoke(is_object auto C::* m, auto* self, Args&&...)
+    -> decltype(self->*m)
     requires (
         sizeof...(Args) == 0 &&
         requires { self->*m; }
@@ -45,6 +49,7 @@ constexpr auto invoke(is_object auto C::* m, auto* self, Args&&...)
 
 template<typename... Args>
 constexpr auto invoke(auto&& f, Args&&... args)
+    -> decltype(f(ASL_FWD(args)...))
     requires requires {
         f(ASL_FWD(args)...);
     }
@@ -52,14 +57,22 @@ constexpr auto invoke(auto&& f, Args&&... args)
     return ASL_FWD(f)(ASL_FWD(args)...);
 }
 
-template<typename F> struct _result_of_helper;
+template<typename Void, typename F, typename... Args>
+struct _invoke_result_helper;
 
 template<typename R, typename... Args>
-struct _result_of_helper<R(Args...)>
+struct _invoke_result_helper<void, R, Args...>
 {
     using type = decltype(invoke(declval<R>(), declval<Args>()...));
 };
 
-template<typename F> using result_of_t = _result_of_helper<F>::type;
+template<typename F, typename... Args>
+using invoke_result_t = _invoke_result_helper<void, F, Args...>::type;
+
+template<typename F, typename... Args>
+concept invocable = requires (F&& f, Args&&... args)
+{
+    invoke(ASL_FWD(f), ASL_FWD(args)...);
+};
 
 } // namespace asl
diff --git a/asl/base/functional_tests.cpp b/asl/base/functional_tests.cpp
index 92c5c7b..991c3c1 100644
--- a/asl/base/functional_tests.cpp
+++ b/asl/base/functional_tests.cpp
@@ -24,11 +24,25 @@ static int some_func1(int x) { return x + 1; }
 [[maybe_unused]] static float some_func1(float x) { return x + 1; }
 static int some_func2(int x, int b) { return x + b; }
 
-static_assert(asl::same_as<asl::result_of_t<Functor()>, int64_t>);
-static_assert(asl::same_as<asl::result_of_t<Functor(int)>, int>);
-static_assert(asl::same_as<asl::result_of_t<decltype(static_cast<float(*)(float)>(some_func1))(float)>, float>);
-static_assert(asl::same_as<asl::result_of_t<decltype(&HasFunction::do_something)(HasFunction, int, float)>, void>);
-static_assert(asl::same_as<asl::result_of_t<decltype(&HasMember::member)(HasMember)>, int>);
+static_assert(asl::same_as<asl::invoke_result_t<int()>, int>);
+static_assert(asl::same_as<asl::invoke_result_t<int(float), float>, int>);
+static_assert(asl::same_as<asl::invoke_result_t<Functor>, int64_t>);
+static_assert(asl::same_as<asl::invoke_result_t<Functor, int>, int>);
+static_assert(asl::same_as<asl::invoke_result_t<decltype(static_cast<float(*)(float)>(some_func1)), float>, float>);
+static_assert(asl::same_as<asl::invoke_result_t<decltype(&HasFunction::do_something), HasFunction, int, float>, void>);
+static_assert(asl::same_as<asl::invoke_result_t<decltype(&HasMember::member), const HasMember>, const int&>);
+
+static_assert(asl::invocable<int()>);
+static_assert(!asl::invocable<int(), int>);
+static_assert(asl::invocable<int(float), float>);
+static_assert(!asl::invocable<int(float), int*>);
+static_assert(asl::invocable<Functor>);
+static_assert(asl::invocable<Functor, int>);
+static_assert(!asl::invocable<Functor, void*>);
+static_assert(asl::invocable<decltype(static_cast<float(*)(float)>(some_func1)), float>);
+static_assert(asl::invocable<decltype(&HasFunction::do_something), HasFunction, int, float>);
+static_assert(!asl::invocable<decltype(&HasFunction::do_something), HasFunction, int, int*>);
+static_assert(asl::invocable<decltype(&HasMember::member), const HasMember>);
 
 ASL_TEST(invoke_member_function)
 {
-- 
cgit