Cleroth · July 19, 2018 20:22 · Jul 19, 2018 · Jul 19, 2018 · Jul 19, 2018
diff --git a/CallbackFunctor → CallbackFunctor.h b/CallbackFunctor → CallbackFunctor.h
diff --git a/CallbackFunctor b/CallbackFunctor
@@ -0,0 +1,69 @@
+namespace detail
+{
+	template <typename Res = void, typename ... Args>
+	class Lambda {
+	public:
+		virtual Res operator()(Args ... args) = 0;
+		virtual ~Lambda() noexcept = default;
+	};
+
+	template <typename T, typename Res, typename ... Args>
+	class LambdaImpl : public Lambda<Res, Args...> {
+	public:
+		LambdaImpl(T t) : _t(t) {}
+		Res operator()(Args ... args) override
+		{
+			return _t(std::forward<Args>(args)...);
+		}
+
+	private:
+		T _t;
+	};
+};
+
+template <typename Res, typename ... Args, typename T>
+std::unique_ptr<detail::Lambda<Res, Args...>> MakeLambda(T t)
+{
+	return std::make_unique<detail::LambdaImpl<T, Res, Args...>>(t);
+}
+
+
+template <typename Res = void, typename ... Args>
+class CallbackFunctor {
+public:
+	CallbackFunctor() {}
+
+	template <typename T>
+	CallbackFunctor(T t)
+	{
+		_lambda = MakeLambda<Res, Args...>(t);
+	}
+
+	template <typename T>
+	void operator=(T t)
+	{
+		_lambda = MakeLambda<Res, Args...>(t);
+	}
+
+	void operator=(std::nullptr_t)
+	{
+		_lambda = nullptr;
+	}
+	template<typename ...Args>
+	auto operator()(Args &&... args) const
+	{
+		if(!_lambda)
+			return Res(0);
+		else
+			return (*_lambda)(std::forward<Args>(args)...);
+	}
+
+	operator bool() const
+	{
+		return (bool)_lambda;
+	}
+
+private:
+	using LambdaType = detail::Lambda<Res, Args...>;
+	std::unique_ptr<LambdaType> _lambda;
+};