#include <iostream>
#include <functional>
#include <vector>
#include <map>
#include <set>
#include <type_traits>
#include <utility>

/////////////////////////////////////////
//
// Listener and Notifier classes:
//
/////////////////////////////////////////

class Listener;
class NotifierBase {
public:
	virtual void disconnect(Listener* object) {}
};

class Listener {
public:
	virtual ~Listener()
	{
		for (auto signal = signals.begin(); signal != signals.end(); ++signal) {
			(*signal)->disconnect(this);
		}
	}

	void registerNotifier(NotifierBase* signal)
	{
		signals.insert(signal);
	}

	void unregisterNotifier(NotifierBase* signal)
	{
		signals.erase(signal);
	}

	std::set<NotifierBase*> signals;
};

template<typename T, typename... Args>
class Notifier : public NotifierBase {
public:
	Notifier() {}
	~Notifier()
	{
		for (auto slot = slots.begin(); slot != slots.end(); ++slot) {
			(*slot).first->unregisterNotifier(this);
		}
	}

	void connect(Listener* object, std::function<void(T, Args...)> slot)
	{
		slots[object] = slot;
		if(object) {
			object->registerNotifier(this);
		}
	}

	void disconnect(Listener* object)
	{
		slots.erase(object);
	}

	void notify(T t, Args...args)
	{
		for (auto slot = slots.begin(); slot != slots.end(); ++slot) {
			(*slot).second(t, args...);
		}
	}

	std::map<Listener*, std::function<void(T, Args...)>> slots;
};

/////////////////////////////////////////
//
// Code which I don't understand but does something clever and produces a compile warning:
//
/////////////////////////////////////////

template<unsigned... Is> struct seq{};
template<unsigned I, unsigned... Is>
struct gen_seq : gen_seq<I-1, I-1, Is...>{};
template<unsigned... Is>
struct gen_seq<0, Is...> : seq<Is...>{};

template<unsigned I> struct placeholder{};

namespace std{
template<unsigned I>
struct is_placeholder< ::placeholder<I> > : integral_constant<int, I>{};
} // std::

namespace aux{
template<unsigned... Is, class F, class... Ts>
auto easy_bind(seq<Is...>, F&& f, Ts&&... vs)
	-> decltype(std::bind(std::forward<F>(f), std::forward<Ts>(vs)..., ::placeholder<1 + Is>()...))
{
    return std::bind(std::forward<F>(f), std::forward<Ts>(vs)..., ::placeholder<1 + Is>()...);
}
} // aux::

template<class R, class C, class... FArgs, class... Args>
auto mem_bind(R (C::*ptmf)(FArgs...), Args&&... vs)
	-> decltype(aux::easy_bind(gen_seq<(sizeof...(FArgs) + 1) - sizeof...(Args)>(), ptmf, std::forward<Args>(vs)...))
{
    // the +1s for 'this' argument
    static_assert(sizeof...(Args) <= sizeof...(FArgs) + 1, "too many arguments to mem_bind");
    return aux::easy_bind(gen_seq<(sizeof...(FArgs) + 1) - sizeof...(Args)>(), ptmf, std::forward<Args>(vs)...);
}

template<class T, class C, class... Args>
auto mem_bind(T C::*ptmd, Args&&... vs)
	-> decltype(aux::easy_bind(gen_seq<1 - sizeof...(Args)>(), ptmd, std::forward<Args>(vs)...))
{
    // just 'this' argument
    static_assert(sizeof...(Args) <= 1, "too many arguments to mem_bind");
    return aux::easy_bind(gen_seq<1 - sizeof...(Args)>(), ptmd, std::forward<Args>(vs)...);
}



/////////////////////////////////////////
//
//  Example:
//
/////////////////////////////////////////

class MyObject : public Listener {
public:
	void onMouseMoved(int x, int y)
	{
		std::cout << __PRETTY_FUNCTION__ << std::endl;
		std::cout << "Mouse moved: " << x << "," << y << std::endl;
	}
};

class MyObject2 : public Listener {
public:
	void mouseMoved(int x, int y)
	{
		std::cout << __PRETTY_FUNCTION__ << std::endl;
		std::cout << "Mouse moved: " << x << "," << y << std::endl;
	}
};

class Button {
public:
	Notifier<int, int> mouseMove; // arguments: (int x, int y)

	void emulateMouseMove(int x, int y)
	{
		mouseMove.notify(x, y);
	}
};


#define CONN(O, M) &O, mem_bind(&decltype(O)::M, O)
#define obj_connect(SRC, SIG, TAR, SLO) SRC.SIG.connect(&TAR, mem_bind(&decltype(TAR)::SLO, TAR))
#define fun_connect(SRC, SIG, SLO) SRC.SIG.connect(nullptr, SLO)

int main()
{
	Button btn;

	MyObject object;
	//btn.mouseMove.connect(&object, std::bind(&MyObject::onMouseMoved, std::ref(object), _1, _2 )); // 'Vanilla' interface
	//btn.mouseMove.connect(&object, std::bind(&decltype::onMouseMoved, std::ref(object), _1, _2 )); // Use decltype
	//btn.mouseMove.connect(&object, mem_bind(&decltype(object)::onMouseMoved, object)); // Use clever mem_bind construct
	btn.mouseMove.connect(CONN(object, onMouseMoved)); // Use convenience macro

	obj_connect(btn, mouseMove, object, onMouseMoved);
	fun_connect(btn, mouseMove, [](int x, int y) {
			std::cout << __PRETTY_FUNCTION__ << std::endl;
			std::cout << x << " x " << y << std::endl;
		} );

	MyObject2 object2;
	btn.mouseMove.connect(CONN(object2, mouseMoved));

	MyObject2* pobject2 = new MyObject2();
	btn.mouseMove.connect(pobject2, mem_bind(&decltype(std::remove_reference(*pobject2))::mouseMoved, std::ref(*pobject2)));


	// Now trigger the notification
	btn.emulateMouseMove(10,10);
}












































































#if 0

#include <iostream>
#include <functional>
#include <vector>
#include <map>
#include <set>
#include <stdio.h>

template<typename T>
class SignalBase {
public:
	virtual T emit(T a) { return a; } 
	T slot(SignalBase* o, T a) { return o->emit(a); }
};

template<typename T>
class Signal : public SignalBase<T> {
public:
	typedef SignalBase<T>* signal_ptr_t;
		
	static T do_emit(signal_ptr_t o1, signal_ptr_t o2, T arg)
	{
		std::cout << __PRETTY_FUNCTION__ << "\n";
		//	printf("%p %p\n", (void*)o1, (void*)o2);
		return o1->slot(o2, arg);
	}

	using bound_emit_t =
		decltype(std::bind(do_emit, signal_ptr_t(), signal_ptr_t(), std::placeholders::_1));

	using mem_t = decltype()


	void connect(Signal<T>& o)
	{	
		connection_map[&o].emplace_back(do_emit, this, &o, std::placeholders::_1);

		if (o.connectee_objects.find(this) == o.connectee_objects.end()) {
			o.connectee_objects.insert(this);
		}
	}

	void disconnect(Signal<T>& o)
	{
		if (connection_map.find(&o) != connection_map.end()) {
			connection_map[&o].clear();
			connection_map.erase(&o);
		}

		if (o.connectee_objects.find(this) != o.connectee_objects.end()) {
			connectee_objects.erase(this);
		}
	}

	void send(T a)
	{
		std::cout << "send: " << a << std::endl;
		for (auto& slot : connection_map) {
			for (auto& conn : slot.second) {
				std::cout << conn(a) << std::endl;
			}
		}
	} 

	virtual ~Signal()
	{
		// Iterate all objects to which this is connected and disconnect from them:
		for (auto& c : connectee_objects) {
			c->disconnect(*this);
		}

		// Iterate all objects connected to this and disconnect them:
		for (auto& kv : connection_map) {
			disconnect(*kv.first);
		}
	}
	
	std::map<Signal<T>*, std::vector<bound_emit_t>> connection_map;
	std::set<Signal<T>*> connectee_objects; // Signals to which this is connected
};

/////////////////////////////////////////////////////////////////////////////////////

template<typename T>
class Signal2 : public Signal<T> {
public:
	Signal2(T t) : t(t) {}
	virtual T emit(T a) override { return a + t;} 
	T t;
};

int main()
{

	std::cout << std::endl << "First:" << std::endl;
	{
		Signal<int> o1;

		{
			Signal2<int> o2(1);
			Signal2<int> o3(1);
			
			o1.connect(o1);
			o1.connect(o2);
			o1.connect(o3);
			
			o1.send(4);
			
			o1.disconnect(o2);
			
			o1.send(5);
		} // implicit o1.disconnect(o3) in o3 destructor.
		
		o1.send(6);
	}

	std::cout << std::endl << "Second:" << std::endl;
	{
		Signal<float>* o = new Signal<float>();
		Signal<float>& o1 = *o;

		{
			Signal2<float> o2(1);
			Signal2<float> o3(1);
			
			o1.connect(o1);
			o1.connect(o2);
			o1.connect(o3);
			
			o1.send(4.1);
			
			delete o;
			std::cout << std::endl << " -- post delete:" << std::endl;

			o1.send(4.2);

		} // implicit o1.disconnect(o3) in o3 destructor.
	}

	std::cout << std::endl << "Third:" << std::endl;
	{
		Signal<std::string> o1;

		{
			Signal2<std::string> o2("a");
			Signal2<std::string> o3("b");
			
			o1.connect(o1);
			o1.connect(o2);
			o1.connect(o3);
			
			o1.send("hello");
			
			o1.disconnect(o2);
			
			o1.send("world");
		} // implicit o1.disconnect(o3) in o3 destructor.
		
		o1.send("nisse");
	}

	return 0;
}

#endif

/////////////////////////////////////////////////////////
// What I would like(tm)
/////////////////////////////////////////////////////////
/*

class Foo {
public:
	Signal<int, float, std::string> changeSignal;

	void worker()
	{
		somethingChangedSignal.emit(42, 1.234, "hello");
	}
};

class Bar {
public:
	Bar(Foo &foo)
	{
		foo.changeSignal.connect(this, &Bar::notifyCallback);
	}

	void notifyCallback(int a, float b, std::string c)
	{
		// ...
	}
};

class Bas {
public:
	void iWannaKnow(int a, float b, std::string c)
	{
		// ...
	}
};

int main()
{
	Foo foo;
	Bar bar(foo);
	Bas bas;
	foo.changeSignal.connect(&bas, &Bas::iWannaKnow);
	foo.worker();
}

*/