State Design pattern

State is behavioral design pattern. FSM with two states and two events.








----------------------------


class State
{
public:
        State(){};
        ~State(){};
        virtual void on(Machine *m) {};
        virtual void off(Machine *m) {} ;
};


class Machine
{
        class State *current;
public:
        Machine();
        ~Machine(){delete current;}
        void setCurrentState(State *s)
        {
                current = s;
        }
        void on();
        void off();
};
class ONN:public State
{
public:
        ONN(){cout<<"ON Ctr"<        ~ONN(){};
        void off(Machine *m);
};
class OFFF:public State
{
public:
        OFFF(){cout<<"OFF Ctr"<        ~OFFF(){};
        void on(Machine *m)
        {
                cout <<"OFF to ON"<
                m->setCurrentState(new ONN());
                delete this;
        }
};
Machine::Machine(){current = new OFFF();}
void ONN::off(Machine *m)
        {
                cout<<"ON to OFF"<                m->setCurrentState(new OFFF());
                delete this;
        }

void Machine::on(){ current->on(this);}
void Machine::off() {current->off(this);}
int main(int argc, char * argv[])
{
        typedef void (Machine::*ptr)();
        ptr ptr_arr[2];
        Machine fsm;
        ptr_arr[0] = &Machine::off;
        ptr_arr[1] = &Machine::on;
        int num;
        while(1)
        {
                cout<<"enter 0-->Off and 1-->On"<                cin>>num;
                (fsm.*ptr_arr[num])();
        }
}


Output:
enter 0-->Off and 1-->On
1
OFF to ON
ON Ctr
enter 0-->Off and 1-->On
1
ON
enter 0-->Off and 1-->On
0
ON to OFF