<?php

/**

 * PHPExcel

 *

 * Copyright (c) 2006 - 2010 PHPExcel

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 *

 * @category   PHPExcel

 * @package    PHPExcel_CachedObjectStorage

 * @copyright  Copyright (c) 2006 - 2010 PHPExcel (http://www.codeplex.com/PHPExcel)

 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt	LGPL

 * @version    1.7.3c, 2010-06-01

 */





/**

 * PHPExcel_CachedObjectStorage_DiscISAM

 *

 * @category   PHPExcel

 * @package    PHPExcel_CachedObjectStorage

 * @copyright  Copyright (c) 2006 - 2010 PHPExcel (http://www.codeplex.com/PHPExcel)

 */

class PHPExcel_CachedObjectStorage_DiscISAM extends PHPExcel_CachedObjectStorage_CacheBase implements PHPExcel_CachedObjectStorage_ICache {



	private $_fileName = null;

	private $_fileHandle = null;





	private function _storeData() {

		$this->_currentObject->detach();



		fseek($this->_fileHandle,0,SEEK_END);

		$offset = ftell($this->_fileHandle);

		fwrite($this->_fileHandle, serialize($this->_currentObject));

		$this->_cellCache[$this->_currentObjectID]	= array('ptr' => $offset,

															'sz'  => ftell($this->_fileHandle) - $offset

														   );

		$this->_currentObjectID = $this->_currentObject = null;

	}	//	function _storeData()





    /**

     *	Add or Update a cell in cache identified by coordinate address

     *

     *	@param	string			$pCoord		Coordinate address of the cell to update

     *	@param	PHPExcel_Cell	$cell		Cell to update

	 *	@return	void

     *	@throws	Exception

     */

	public function addCacheData($pCoord, PHPExcel_Cell $cell) {

		if (($pCoord !== $this->_currentObjectID) && ($this->_currentObjectID !== null)) {

			$this->_storeData();

		}



		$this->_currentObjectID = $pCoord;

		$this->_currentObject = $cell;



		return $cell;

	}	//	function addCacheData()





    /**

     * Get cell at a specific coordinate

     *

     * @param 	string 			$pCoord		Coordinate of the cell

     * @throws 	Exception

     * @return 	PHPExcel_Cell 	Cell that was found, or null if not found

     */

	public function getCacheData($pCoord) {

		if ($pCoord === $this->_currentObjectID) {

			return $this->_currentObject;

		}

		$this->_storeData();



		//	Check if the entry that has been requested actually exists

		if (!isset($this->_cellCache[$pCoord])) {

			//	Return null if requested entry doesn't exist in cache

			return null;

		}



		//	Set current entry to the requested entry

		$this->_currentObjectID = $pCoord;

		fseek($this->_fileHandle,$this->_cellCache[$pCoord]['ptr']);

		$this->_currentObject = unserialize(fread($this->_fileHandle,$this->_cellCache[$pCoord]['sz']));

		//	Re-attach the parent worksheet

		$this->_currentObject->attach($this->_parent);



		//	Return requested entry

		return $this->_currentObject;

	}	//	function getCacheData()





	public function unsetWorksheetCells() {

		if(!is_null($this->_currentObject)) {

			$this->_currentObject->detach();

			$this->_currentObject = $this->_currentObjectID = null;

		}

		$this->_cellCache = array();



		//	detach ourself from the worksheet, so that it can then delete this object successfully

		$this->_parent = null;



		//	Close down the temporary cache file

		$this->__destruct();

	}	//	function unsetWorksheetCells()





	public function __construct(PHPExcel_Worksheet $parent) {

		parent::__construct($parent);

		if (is_null($this->_fileHandle)) {

			if (function_exists('posix_getpid')) {

				$baseUnique = posix_getpid();

			} else {

				$baseUnique = mt_rand();

			}

			$this->_fileName = sys_get_temp_dir().'/PHPExcel.'.uniqid($baseUnique,true).'.cache';

			$this->_fileHandle = fopen($this->_fileName,'a+');

		}

	}	//	function __construct()





	public function __destruct() {

		if (!is_null($this->_fileHandle)) {

			fclose($this->_fileHandle);

			unlink($this->_fileName);

		}

		$this->_fileHandle = null;

	}	//	function __destruct()



}