设计模式C++实现十四：备忘录模式

备忘录模式（Memento）：在不破坏封装性的前提下，捕获一个对象的内部状态，并在该对象之外保存这个状态，这样以后就可以将该对象恢复到之前保存的状态。

备忘录模式比较适用于功能较复杂的，但需要维护和记录属性历史的类，或者需要保存的属性只是众多属性中的一小部分。如果某个系统中使用命令模式时，需要实现命令的撤销功能，那么备忘录模式可以存储可撤销操作的状态。

#ifndef MEMENTO_H
#define MEMENTO_H
#include<iostream>
#include<string>
using namespace std;
class RoleStateMemento;
class GameRole
{
friend class RoleStateMemento;
int vit;
int atk;
int dfs;
public:
GameRole():vit(100),atk(100),dfs(100){}
//void Initial();
void Fight1();
void Fight2();
void RecoveryState(RoleStateMemento m);
RoleStateMemento SaveState();
void StateDisplay();
};

class RoleStateMemento
{
friend class GameRole;
int vit;
int atk;
int dfs;
public:
RoleStateMemento(){}
RoleStateMemento(GameRole role);

};

class RoleStateDirector
{
RoleStateMemento memento;
public:
RoleStateDirector(GameRole role);
RoleStateDirector(RoleStateMemento role);
RoleStateMemento ReturnMemento();
};

void GameRole::Fight1()
{
vit = 80;
atk = 60;
dfs = 50;
}
void GameRole::Fight2()
{
vit = 30;
atk = 40;
dfs = 40;
}
void GameRole::RecoveryState(RoleStateMemento m)
{
vit = m.vit;
atk = m.atk;
dfs = m.dfs;
}
RoleStateMemento GameRole::SaveState()
{
return RoleStateMemento(*this);
}
void GameRole::StateDisplay()
{
cout << "Vitality: " << vit << endl;
cout << "Attack: " << atk << endl;
cout << "Defense: " << dfs << endl;
}

RoleStateMemento::RoleStateMemento(GameRole role)
{
vit = role.vit;
atk = role.atk;
dfs = role.dfs;
}
RoleStateDirector::RoleStateDirector(GameRole role):memento(role){}
RoleStateDirector::RoleStateDirector(RoleStateMemento role) : memento(role){}
RoleStateMemento RoleStateDirector::ReturnMemento()
{
return memento;
}
#endif

#include"Memento.h"
int main()
{
GameRole Xie;
Xie.StateDisplay();

Xie.Fight1();
Xie.StateDisplay();

RoleStateDirector Dir(Xie.SaveState());

Xie.Fight2();
Xie.StateDisplay();

Xie.RecoveryState(Dir.ReturnMemento());
Xie.StateDisplay();
return 0;
}