备忘录模式

#include <iostream>
#include <string>
using namespace std;

class Originator;

class Memento {
public:
    ~Memento() {}
private:
    friend class Originator;
    Memento() { m_state = "NULL"; }
    void setState(string state) { m_state = state; }
    string getState() { return m_state; }
private:
    string m_state;
};

class Originator {
public:
    Memento* createMemento() { return new Memento(); }
    void setMemento(Memento* memento) { m_state = memento->getState(); }
public:
    void setState(string state) { m_state = state; }
    string getState() { return m_state; }
private:
    string m_state;
};



class CareTaker {
public:
    Memento* getMemento() { return m_pMemento; }
    void setMemento(Memento* pMemento) { m_pMemento = pMemento; }
    ~CareTaker() { delete m_pMemento; }
private:
    Memento* m_pMemento;
};

int main() {
    Originator o;
    o.setState("ON");
    cout << "o state : " << o.getState() << endl;

    CareTaker c;
    c.setMemento(o.createMemento());

    o.setState("OFF");
    cout << "o state : " << o.getState() << endl;

    o.setMemento(c.getMemento());
    cout << "o state : " << o.getState() << endl;


    return 0;
}