设计模式(18)memento模式

class originator
{
  private $state1;
  private $state2;
  public function setState($state1,$state2){
    $this->state1 = $state1;
    $this->state2 = $state2;
  }
  public function setMemento(Memento $m){ 
     $this->state1 = $m->getState1();
     $this->state2 = $m->getState2();
  }
  public function createMemento(){ 
     return new Memento($this->state1,$this->state2);
  }
  public function getState1(){
    return $this->state1;
  }
  public function getState2(){
    return $this->state2;
  }
}

class Memento
{
  
  private $state1;
  private $state2;
  public function __construct($state1,$state2){
    $this->state1 = $state1; 
    $this->state2 = $state2; 
  }
  public function getState1(){
    return $this->state1;
  }
  public function getState2(){
    return $this->state2;
  }
}
class Caretaker
{
  private $mementos;
  public function  add(Memento $m){
    $this->mementos[] = $m;
  }
  public function getLast(){  
    $len = count($this->mementos);  
    if($len < 1){  
      return;  
    }  

    $temp = $this->mementos[$len - 1];  
    unset($this->mementos[$len - 1]);
    return $temp;
  }
}
//测试代码块

$o = new originator();
$o->setState(1,2);
$caretaker = new Caretaker();
echo $o->getState1().','.$o->getState2()."\n";
//保存这个状态
$caretaker->add($o->createMemento());
$o->setState(4,6);
echo $o->getState1().','.$o->getState2()."\n";
$caretaker->add($o->createMemento());
//返回上个状态
$o->setMemento($caretaker->getLast());
echo $o->getState1().','.$o->getState2()."\n";
$o->setMemento($caretaker->getLast());
echo $o->getState1().','.$o->getState2()."\n";