设计模式(16)iterator模式

abstract class IIterator  
{  
    public abstract function First();  
    public abstract function Next();  
    public abstract function IsDone();  
    public abstract function CurrentItem();  
}  
  
//具体迭代器  
class ConcreteIterator extends IIterator  
{  
    private $aggre;  
    private $current = 0;  
    public function __construct($obj)  
    {  
        $this->aggre = $obj->list;  
    }  
    //返回第一个  
    public function First()  
    {  
        return $this->aggre[0];  
    }  
  
    //返回下一个  
    public function  Next()  
    {  
        $this->current++;  
        if($this->current<count($this->aggre))  
        {  
            return $this->aggre[$this->current];  
        }  
        return false;  
    }  
  
    //返回是否IsDone  
    public function IsDone()  
    {  
        return $this->current>=count($this->aggre)?true:false;  
    }  
  
    //返回当前聚集对象  
    public function CurrentItem()  
    {  
        return $this->aggre[$this->current];  
    }  
}  

interface Aggregate {  
    public function add($obj);  
    public function remove($obj);  
    public function iterator();  
}  
class ConcreteAggregate implements Aggregate {  
    public $list;
    public function __construct(){
      $this->list = [];
    }
    public function add($item) {  
      $this->list[] = $item;
    }  
  
    public function iterator() {  
        return new ConcreteIterator($this);  
    }  
  
    public function remove($item) {  
      unset($this->list[array_search($this->list,$item)]);
    }  
}  

//测试代码
$aggregate = new ConcreteAggregate();
$aggregate->add(1);
$aggregate->add(10);
$iterator = $aggregate->iterator($aggregate);
echo $iterator->First();
echo $iterator->Next();