迭代器模式 （Iterator），又叫做游标（Cursor）模式。提供一种方法访问一个容器（Container）对象中各个元素，而又不需暴露该对象的内部细节。
当你需要访问一个聚合对象，而且不管这些对象是什么都需要遍历的时候，就应该考虑使用迭代器模式。另外，当需要对聚集有多种方式遍历时，可以考虑去使用迭代器模式。迭代器模式为遍历不同的聚集结构提供如开始、下一个、是否结束、当前哪一项等统一的接口。
php标准库（SPL）中提供了迭代器接口 Iterator，要实现迭代器模式，实现该接口即可。
<?phpclass 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); ???}}// client$data = array(1, 2, 3, 4, 5);$sa = new sample($data);foreach ($sa AS $key => $row) { ???echo $key, ‘ ‘, $row, ‘<br />‘;}/* 输出：0 11 22 33 44 5 *///Yii FrameWork Democlass 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 />‘;}/* 输出：112233 */?>PHP设计模式 - 迭代器模式
原文地址：https://www.cnblogs.com/taozi32/p/9226824.html