PHP中迭代器的简单实现及Yii框架中的迭代器实现方法示例

/**
* Iterator模式的简单实现类
*/
class sample implements Iterator {
  private $_items ;
 
  public function __construct(&$data) {
    $this- _items = $data;
  }
  public function current() {
    return current($this- _items);
  }
 
  public function next() {
    next($this- _items);  
  }
 
  public function key() {
    return key($this- _items);
  }
 
  public function rewind() {
    reset($this- _items);
  }
 
  public function valid() {
    return ($this- current() !== FALSE);
  }
}
 
/** DEMO */
$data = array(1, 2, 3, 4, 5);
$sa = new sample($data);
foreach ($sa AS $key =  $row) {
  echo $key, ' ', $row, '<br / ';
}

abstract public void Iterator::next ( void )

$data = array('0' =  11, "" =  22, 's3' =  33, 0, 0, "", false, 0, 1);

class CMapIterator implements Iterator {
/**
* @var array the data to be iterated through
*/
  private $_d;
/**
* @var array list of keys in the map
*/
  private $_keys;
/**
* @var mixed current key
*/
  private $_key;
 
/**
* Constructor.
* @param array the data to be iterated through
*/
  public function __construct(&$data) {
    $this- _d=&$data;
    $this- _keys=array_keys($data);
  }
 
/**
* Rewinds internal array pointer.
* This method is required by the interface Iterator.
*/
  public function rewind() {                                         
    $this- _key=reset($this- _keys);
  }
 
/**
* Returns the key of the current array element.
* This method is required by the interface Iterator.
* @return mixed the key of the current array element
*/
  public function key() {
    return $this- _key;
  }
 
/**
* Returns the current array element.
* This method is required by the interface Iterator.
* @return mixed the current array element
*/
  public function current() {
    return $this- _d[$this- _key];
  }
 
/**
* Moves the internal pointer to the next array element.
* This method is required by the interface Iterator.
*/
  public function next() {
    $this- _key=next($this- _keys);
  }
 
/**
* Returns whether there is an element at current position.
* This method is required by the interface Iterator.
* @return boolean
*/
  public function valid() {
    return $this- _key!==false;
  }
}
 
$data = array('s1' =  11, 's2' =  22, 's3' =  33);
$it = new CMapIterator($data);
foreach ($it as $row) {
  echo $row, '<br / ';
}