repos/Callback_37/Callback_37/template_H.h

#pragma once

// https://gist.github.com/hlorenzi/8ce4184f8416665002a5


template <typename TReturn, typename... TArgs>
class Callback
{
public:
	template <typename TObject, TReturn(TObject::* member_function)(TArgs...)>
	static Callback<TReturn, TArgs...> make_member(TObject* user_data)
	{
		Callback<TReturn, TArgs...> callback;
		callback.user_data = (void*)user_data;
		callback.wrapped_call = wrapped_member_call<TObject, member_function>;
		return callback;
	}


	template <typename TObject, TReturn(*static_function)(TObject*, TArgs...)>
	static Callback<TReturn, TArgs...> make_userdata(TObject* user_data)
	{
		Callback<TReturn, TArgs...> callback;
		callback.user_data = (void*)user_data;
		callback.wrapped_call = wrapped_userdata_call<TObject, static_function>;
		return callback;
	}


	template <TReturn(*static_function)(TArgs...)>
	static Callback<TReturn, TArgs...> make_static()
	{
		Callback<TReturn, TArgs...> callback;
		callback.user_data = nullptr;
		callback.wrapped_call = wrapped_static_call<static_function>;
		return callback;
	}


	TReturn call(TArgs... args)
	{
		return this->wrapped_call(this->user_data, args...);
	}


protected:
	TReturn(*wrapped_call)(void*, TArgs...);
	void* user_data;


	template <typename TObject, TReturn(TObject::* member_function)(TArgs...)>
	static TReturn wrapped_member_call(void* user_data, TArgs... args)
	{
		return (((TObject*)user_data)->*member_function)(args...);
	}


	template <typename TObject, TReturn(*static_function)(TObject*, TArgs...)>
	static TReturn wrapped_userdata_call(void* user_data, TArgs... args)
	{
		return static_function((TObject*)user_data, args...);
	}


	template <TReturn(*static_function)(TArgs...)>
	static TReturn wrapped_static_call(void* user_data, TArgs... args)
	{
		return static_function(args...);
	}
};