#pragma once

#ifndef MEMENTO_H 

#define MEMENTO_H 

#include <string> 

typedef std::string State; 

class Memento; 

class Originator 
{ 
public: 
  Originator(const State& rState); 
  Originator(); 
  ~Originator(); 
  Memento*  CreateMemento(); 
  void      SetMemento(Memento* pMemento); 
  State     GetState(); 
  void      SetState(const State& rState); 
  void      RestoreState(Memento* pMemento); 
  void      PrintState(); 

private: 
  State      m_State; 
}; 

// 把Memento 的接口函数都设置为私有的,而Originator 是它的友元, 
// 这样保证了只有Originator 可以对其访问 
class Memento 
{ 
private: 
  friend class Originator; 
  Memento(const State& rState); 
  void   SetState(const State& rState); 
  State  GetState(); 
  State  m_State; 
}; 

#endif

#include "StdAfx.h"
#include "memento_impl.h"

#include <iostream> 

Originator::Originator() 
{ 
} 

Originator::Originator(const State& rState) 
: m_State(rState) 
{ 
} 

Originator::~Originator() 
{ 
} 

State Originator::GetState() 
{ 
  return m_State; 
} 

void Originator::SetState(const State& rState) 
{ 
  m_State = rState; 
} 

Memento* Originator::CreateMemento() 
{ 
  return new Memento(m_State); 
} 

void Originator::RestoreState(Memento* pMemento) 
{ 
  if (NULL != pMemento) 
  { 
    m_State = pMemento->GetState(); 
  } 
} 

void Originator::PrintState() 
{ 
  std::cout << "State = " << m_State << std::endl; 
} 

Memento::Memento(const State& rState) 
: m_State(rState) 
{ 
} 

State Memento::GetState() 
{ 
  return m_State; 
} 

void Memento::SetState(const State& rState) 
{ 
  m_State = rState; 
}

// Memento.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"

#include "memento_impl.h"
#include <stdlib.h>
//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.这样以后就可将该对象恢复到原先保存的状态. 
int _tmain(int argc, _TCHAR* argv[])
{
  // 创建一个原发器 
  Originator* pOriginator = new Originator("old state"); 
  pOriginator->PrintState(); 

  // 创建一个备忘录存放这个原发器的状态 
  Memento *pMemento = pOriginator->CreateMemento(); 

  // 更改原发器的状态 
  pOriginator->SetState("new state"); 

  pOriginator->PrintState(); 
  // 通过备忘录把原发器的状态还原到之前的状态 
  pOriginator->RestoreState(pMemento); 

  pOriginator->PrintState(); 

  delete pOriginator; 
  delete pMemento;
  system("pause");

  return 0;
}