C++ FSM implementation

FSM.h

#ifndef FSM_H
#define FSM_H

#include "Component.h"

ZCOMPONENT_INHERITS(FSM, Component)
public:
	class State
	{
		public:
			FSM* fsm;

		public:
			virtual void Update()      {}
			virtual void FixedUpdate() {}
			virtual void Exit()        {}
	};

	class State0Params : public State
	{
		public:
			virtual void Enter() {}
	};

	template< class T >
	class State1Param : public State
	{
		public:
			virtual void Enter(T p) = 0;
	};

	template< class T0, class T1 >
	class State2Params : public State
	{
		public:
			virtual void Enter(T0 p0, T1 p1) = 0;
	};

private:
	State* state;

public:
	ZEvent< void(State*, State*) > OnStatusChanged;

private:
	void SetStateCommon(State* state);

public:
	FSM();
	ZCOMPONENT_IMPLEMENTS_UPDATE
	ZCOMPONENT_IMPLEMENTS_FIXED_UPDATE

public:
	void SetState(State0Params* state);

	template< class T >
	void SetState(State1Param< T >* state, T p)
	{
		State* old_state = this->state;
		SetStateCommon(state);
		if(state)
			state->Enter(p);
		OnStatusChanged(old_state, state);
	}

	template< class T0, class T1 >
	void SetState(State2Params< T0, T1 >* state, T0 p0, T1 p1)
	{
		State* old_state = this->state;
		SetStateCommon(state);
		if(state)
			state->Enter(p0, p1);
		OnStatusChanged(old_state, state);
	}
};

#endif