類實現迭代循環

Question

我有個問題與實現Iterator接口 下面是代碼：

class User_Model_Users implements Iterator, Countable 
{ 

    protected $_count; 
    protected $_gateway; 
    protected $_resultSet; 

    public function __construct($results, $gateway) 
    { 
     $this->setGateway($gateway); 
     $this->_resultSet = $results; 
    } 

    public function setGateway(User_Model_UserGateway $gateway) 
    { 
     $this->_gateway = $gateway; 
     return $this; 
    } 

    public function getGateway() 
    { 
     return $this->_gateway; 
    } 

    public function count() 
    { 
     if (null === $this->_count) { 
      $this->_count = count($this->_resultSet); 
     } 
     return $this->_count; 
    } 

    public function current() 
    { 
     if ($this->_resultSet instanceof Iterator) { 
      $key = $this->_resultSet->key(); 
     } else { 
      $key = key($this->_resultSet); 
     } 
     $result = $this->_resultSet [$key]; 
     if (!$result instanceof User_Model_User) { 
      $gateway = $this->getGateway(); 
      $result = $gateway->createUser($result); 
      $this->_resultSet [$key] = $result; 
     } 
     return $result; 
    } 

    public function key() 
    { 
     return key($this->_resultSet); 
    } 

    public function next() 
    { 
     return next($this->_resultSet); 
    } 

    public function rewind() 
    { 
     return reset($this->_resultSet); 
    } 

    public function valid() 
    { 
     return (bool) $this->current(); 
    } 

} 

其$結果我提供Zend_Db_Table_Rowset但它可以是也其他物體或陣列。 我該如何解決這個問題，以便我在foreach循環中工作？ 我沒有收到任何錯誤，因爲它是一個無限循環。

Answer 1

胡亂猜測（還沒有真正開始鑽研代碼）：

由於您實現有效的（）是

public function valid() 
{ 
    return (bool) $this->current(); 
} 

你應該確保電流（）時，有沒有返回false更多的元素

public function current() 
{ 
    if ($this->_resultSet instanceof Iterator) { 
     $key = $this->_resultSet->key(); 
    } else { 
     $key = key($this->_resultSet); 
    } 

    if (is_null($key) ) { // could also be is_null($key)||false===$key, not sure... 
     return false; 
    } 

    $result = $this->_resultSet[$key]; 
    if (!$result instanceof User_Model_User) { 
     $gateway = $this->getGateway(); 
     $result = $gateway->createUser($result); 
     $this->_resultSet[$key] = $result; 
    } 
    return $result; 
} 

，並順便說一句：您的功能鍵（）不執行instanceof Iterator情況類似電流（）一樣。

---

測試腳本：

<?php 
class User_Model_Users implements Iterator, Countable 
{ 
    protected $_count; 
    protected $_gateway; 
    protected $_resultSet; 

    public function __construct($results, $gateway) 
    { 
     $this->setGateway($gateway); 
     $this->_resultSet = $results; 
     $this->_count = null; 
    } 

    public function setGateway(User_Model_UserGateway $gateway) 
    { 
     $this->_gateway = $gateway; 
     return $this; 
    } 

    public function getGateway() 
    { 
     return $this->_gateway; 
    } 

    public function count() 
    { 
     if (is_null($this->_count)) { 
      $this->_count = count($this->_resultSet); 
     } 
     return $this->_count; 
    } 

    public function current() 
    { 
     if ($this->_resultSet instanceof Iterator) { 
      $key = $this->_resultSet->key(); 
     } else { 
      $key = key($this->_resultSet); 
     } 
     if (is_null($key)) { 
      return false; 
     } 

     $result = $this->_resultSet[$key]; 
     if (!$result instanceof User_Model_User) { 
      $gateway = $this->getGateway(); 
      $result = $gateway->createUser($result); 
      $this->_resultSet[$key] = $result; 
     } 
     return $result; 
    } 

    public function key() 
    { 
     return key($this->_resultSet); 
    } 

    public function next() 
    { 
     return next($this->_resultSet); 
    } 

    public function rewind() 
    { 
     return reset($this->_resultSet); 
    } 

    public function valid() 
    { 
     return (bool) $this->current(); 
    } 
} 

class User_Model_User { 
    protected $x, $y; 

    public function __construct($x, $y) { 
     $this->x = $x; 
     $this->y = $y; 
    } 
} 

class User_Model_UserGateway { 
    protected $id; 
    public function __construct() { 
     $this->id = time(); 
    } 

    public function createUser($x) { 
     echo "User_Model_UserGateway::createUser($x)\n"; 
     return new User_Model_User($x, $this->id); 
    } 
} 

$a = array('a', 'b', 'c', 'd'); 
$users = new User_Model_Users($a, new User_Model_UserGateway); 
foreach($users as $u) { 
    print_r($u); 
} 

打印

User_Model_UserGateway::createUser(a) 
User_Model_User Object 
(
    [x:protected] => a 
    [y:protected] => 1311167311 
) 
User_Model_UserGateway::createUser(b) 
User_Model_User Object 
(
    [x:protected] => b 
    [y:protected] => 1311167311 
) 
User_Model_UserGateway::createUser(c) 
User_Model_User Object 
(
    [x:protected] => c 
    [y:protected] => 1311167311 
) 
User_Model_UserGateway::createUser(d) 
User_Model_User Object 
(
    [x:protected] => d 
    [y:protected] => 1311167311 
)