source: sourcecode/application/libraries/PHPExcel/CachedObjectStorage/Memory.php @ 2

<?php
/**
 * PHPExcel
 *
 * Copyright (c) 2006 - 2014 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 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
 * @license    http://www.gnu.org/licenses/old-licenses/lgpl-2.1.txt    LGPL
 * @version    1.8.0, 2014-03-02
 */


/**
 * PHPExcel_CachedObjectStorage_Memory
 *
 * @category   PHPExcel
 * @package    PHPExcel_CachedObjectStorage
 * @copyright  Copyright (c) 2006 - 2014 PHPExcel (http://www.codeplex.com/PHPExcel)
 */
class PHPExcel_CachedObjectStorage_Memory extends PHPExcel_CachedObjectStorage_CacheBase implements PHPExcel_CachedObjectStorage_ICache {

    /**
     * Dummy method callable from CacheBase, but unused by Memory cache
     *
         * @return      void
     */
        protected function _storeData() {
        }       //      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   $cell           Cell to update
         * @return      PHPExcel_Cell
     * @throws  PHPExcel_Exception
     */
        public function addCacheData($pCoord, PHPExcel_Cell $cell) {
                $this->_cellCache[$pCoord] = $cell;

                //      Set current entry to the new/updated entry
                $this->_currentObjectID = $pCoord;

                return $cell;
        }       //      function addCacheData()


    /**
     * Get cell at a specific coordinate
     *
     * @param   string                  $pCoord         Coordinate of the cell
     * @throws  PHPExcel_Exception
     * @return  PHPExcel_Cell   Cell that was found, or null if not found
     */
        public function getCacheData($pCoord) {
                //      Check if the entry that has been requested actually exists
                if (!isset($this->_cellCache[$pCoord])) {
                        $this->_currentObjectID = NULL;
                        //      Return null if requested entry doesn't exist in cache
                        return null;
                }

                //      Set current entry to the requested entry
                $this->_currentObjectID = $pCoord;

                //      Return requested entry
                return $this->_cellCache[$pCoord];
        }       //      function getCacheData()


        /**
         * Clone the cell collection
         *
         * @param       PHPExcel_Worksheet      $parent         The new worksheet
         * @return      void
         */
        public function copyCellCollection(PHPExcel_Worksheet $parent) {
                parent::copyCellCollection($parent);

                $newCollection = array();
                foreach($this->_cellCache as $k => &$cell) {
                        $newCollection[$k] = clone $cell;
                        $newCollection[$k]->attach($this);
                }

                $this->_cellCache = $newCollection;
        }


        /**
         * Clear the cell collection and disconnect from our parent
         *
         * @return      void
         */
        public function unsetWorksheetCells() {
                //      Because cells are all stored as intact objects in memory, we need to detach each one from the parent
                foreach($this->_cellCache as $k => &$cell) {
                        $cell->detach();
                        $this->_cellCache[$k] = null;
                }
                unset($cell);

                $this->_cellCache = array();

                //      detach ourself from the worksheet, so that it can then delete this object successfully
                $this->_parent = null;
        }       //      function unsetWorksheetCells()

}