1: <?php
  2: /**
  3:  * CDataProviderIterator class file.
  4:  *
  5:  * @author Charles Pick <charles.pick@gmail.com>
  6:  * @link http://www.yiiframework.com/
  7:  * @copyright 2008-2013 Yii Software LLC
  8:  * @license http://www.yiiframework.com/license/
  9:  */
 10: 
 11: /**
 12:  * CDataProviderIterator allows iteration over large data sets without holding the entire set in memory.
 13:  *
 14:  * CDataProviderIterator iterates over the results of a data provider, starting at the first page
 15:  * of results and ending at the last page. It is usually only suited for use with {@link CActiveDataProvider}.
 16:  *
 17:  * For example, the following code will iterate over all registered users (active record class User) without
 18:  * running out of memory, even if there are millions of users in the database.
 19:  * <pre>
 20:  * $dataProvider = new CActiveDataProvider("User");
 21:  * $iterator = new CDataProviderIterator($dataProvider);
 22:  * foreach($iterator as $user) {
 23:  *   echo $user->name."\n";
 24:  * }
 25:  * </pre>
 26:  *
 27:  * @property CDataProvider $dataProvider the data provider to iterate over
 28:  * @property integer $totalItemCount the total number of items in the iterator
 29:  *
 30:  * @author Charles Pick <charles.pick@gmail.com>
 31:  * @author Carsten Brandt <mail@cebe.cc>
 32:  * @package system.web
 33:  * @since 1.1.13
 34:  */
 35: class CDataProviderIterator extends CComponent implements Iterator, Countable
 36: {
 37:     private $_dataProvider;
 38:     private $_currentIndex=-1;
 39:     private $_currentPage=0;
 40:     private $_totalItemCount=-1;
 41:     private $_items;
 42: 
 43:     /**
 44:      * Constructor.
 45:      * @param CDataProvider $dataProvider the data provider to iterate over
 46:      * @param integer $pageSize pageSize to use for iteration. This is the number of objects loaded into memory at the same time.
 47:      */
 48:     public function __construct(CDataProvider $dataProvider, $pageSize=null)
 49:     {
 50:         $this->_dataProvider=$dataProvider;
 51:         $this->_totalItemCount=$dataProvider->getTotalItemCount();
 52: 
 53:         if(($pagination=$this->_dataProvider->getPagination())===false)
 54:             $this->_dataProvider->setPagination($pagination=new CPagination());
 55: 
 56:         if($pageSize!==null)
 57:             $pagination->setPageSize($pageSize);
 58:     }
 59: 
 60:     /**
 61:      * Returns the data provider to iterate over
 62:      * @return CDataProvider the data provider to iterate over
 63:      */
 64:     public function getDataProvider()
 65:     {
 66:         return $this->_dataProvider;
 67:     }
 68: 
 69:     /**
 70:      * Gets the total number of items to iterate over
 71:      * @return integer the total number of items to iterate over
 72:      */
 73:     public function getTotalItemCount()
 74:     {
 75:         return $this->_totalItemCount;
 76:     }
 77: 
 78:     /**
 79:      * Loads a page of items
 80:      * @return array the items from the next page of results
 81:      */
 82:     protected function loadPage()
 83:     {
 84:         $this->_dataProvider->getPagination()->setCurrentPage($this->_currentPage);
 85:         return $this->_items=$this->dataProvider->getData(true);
 86:     }
 87: 
 88:     /**
 89:      * Gets the current item in the list.
 90:      * This method is required by the Iterator interface.
 91:      * @return mixed the current item in the list
 92:      */
 93:     public function current()
 94:     {
 95:         return $this->_items[$this->_currentIndex];
 96:     }
 97: 
 98:     /**
 99:      * Gets the key of the current item.
100:      * This method is required by the Iterator interface.
101:      * @return integer the key of the current item
102:      */
103:     public function key()
104:     {
105:         $pageSize=$this->_dataProvider->getPagination()->getPageSize();
106:         return $this->_currentPage*$pageSize+$this->_currentIndex;
107:     }
108: 
109:     /**
110:      * Moves the pointer to the next item in the list.
111:      * This method is required by the Iterator interface.
112:      */
113:     public function next()
114:     {
115:         $pageSize=$this->_dataProvider->getPagination()->getPageSize();
116:         $this->_currentIndex++;
117:         if($this->_currentIndex >= $pageSize)
118:         {
119:             $this->_currentPage++;
120:             $this->_currentIndex=0;
121:             $this->loadPage();
122:         }
123:     }
124: 
125:     /**
126:      * Rewinds the iterator to the start of the list.
127:      * This method is required by the Iterator interface.
128:      */
129:     public function rewind()
130:     {
131:         $this->_currentIndex=0;
132:         $this->_currentPage=0;
133:         $this->loadPage();
134:     }
135: 
136:     /**
137:      * Checks if the current position is valid or not.
138:      * This method is required by the Iterator interface.
139:      * @return boolean true if this index is valid
140:      */
141:     public function valid()
142:     {
143:         return $this->key() < $this->_totalItemCount;
144:     }
145: 
146:     /**
147:      * Gets the total number of items in the dataProvider.
148:      * This method is required by the Countable interface.
149:      * @return integer the total number of items
150:      */
151:     public function count()
152:     {
153:         return $this->_totalItemCount;
154:     }
155: }