source: sourcecode/system/libraries/Cache/Cache.php @ 1

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 4.3.2 or newer
 *
 * @package             CodeIgniter
 * @author              ExpressionEngine Dev Team
 * @copyright   Copyright (c) 2006 - 2012 EllisLab, Inc.
 * @license             http://codeigniter.com/user_guide/license.html
 * @link                http://codeigniter.com
 * @since               Version 2.0
 * @filesource  
 */

// ------------------------------------------------------------------------

/**
 * CodeIgniter Caching Class 
 *
 * @package             CodeIgniter
 * @subpackage  Libraries
 * @category    Core
 * @author              ExpressionEngine Dev Team
 * @link                
 */
class CI_Cache extends CI_Driver_Library {
        
        protected $valid_drivers        = array(
                'cache_apc', 'cache_file', 'cache_memcached', 'cache_dummy'
        );

        protected $_cache_path          = NULL;         // Path of cache files (if file-based cache)
        protected $_adapter                     = 'dummy';
        protected $_backup_driver;
        
        // ------------------------------------------------------------------------

        /**
         * Constructor
         *
         * @param array
         */
        public function __construct($config = array())
        {
                if ( ! empty($config))
                {
                        $this->_initialize($config);
                }
        }

        // ------------------------------------------------------------------------

        /**
         * Get 
         *
         * Look for a value in the cache.  If it exists, return the data 
         * if not, return FALSE
         *
         * @param       string  
         * @return      mixed           value that is stored/FALSE on failure
         */
        public function get($id)
        {       
                return $this->{$this->_adapter}->get($id);
        }

        // ------------------------------------------------------------------------

        /**
         * Cache Save
         *
         * @param       string          Unique Key
         * @param       mixed           Data to store
         * @param       int                     Length of time (in seconds) to cache the data
         *
         * @return      boolean         true on success/false on failure
         */
        public function save($id, $data, $ttl = 60)
        {
                return $this->{$this->_adapter}->save($id, $data, $ttl);
        }

        // ------------------------------------------------------------------------

        /**
         * Delete from Cache
         *
         * @param       mixed           unique identifier of the item in the cache
         * @return      boolean         true on success/false on failure
         */
        public function delete($id)
        {
                return $this->{$this->_adapter}->delete($id);
        }

        // ------------------------------------------------------------------------

        /**
         * Clean the cache
         *
         * @return      boolean         false on failure/true on success
         */
        public function clean()
        {
                return $this->{$this->_adapter}->clean();
        }

        // ------------------------------------------------------------------------

        /**
         * Cache Info
         *
         * @param       string          user/filehits
         * @return      mixed           array on success, false on failure      
         */
        public function cache_info($type = 'user')
        {
                return $this->{$this->_adapter}->cache_info($type);
        }

        // ------------------------------------------------------------------------
        
        /**
         * Get Cache Metadata
         *
         * @param       mixed           key to get cache metadata on
         * @return      mixed           return value from child method
         */
        public function get_metadata($id)
        {
                return $this->{$this->_adapter}->get_metadata($id);
        }
        
        // ------------------------------------------------------------------------

        /**
         * Initialize
         *
         * Initialize class properties based on the configuration array.
         *
         * @param       array   
         * @return      void
         */
        private function _initialize($config)
        {        
                $default_config = array(
                                'adapter',
                                'memcached'
                        );

                foreach ($default_config as $key)
                {
                        if (isset($config[$key]))
                        {
                                $param = '_'.$key;

                                $this->{$param} = $config[$key];
                        }
                }

                if (isset($config['backup']))
                {
                        if (in_array('cache_'.$config['backup'], $this->valid_drivers))
                        {
                                $this->_backup_driver = $config['backup'];
                        }
                }
        }

        // ------------------------------------------------------------------------

        /**
         * Is the requested driver supported in this environment?
         *
         * @param       string  The driver to test.
         * @return      array
         */
        public function is_supported($driver)
        {
                static $support = array();

                if ( ! isset($support[$driver]))
                {
                        $support[$driver] = $this->{$driver}->is_supported();
                }

                return $support[$driver];
        }

        // ------------------------------------------------------------------------

        /**
         * __get()
         *
         * @param       child
         * @return      object
         */
        public function __get($child)
        {
                $obj = parent::__get($child);

                if ( ! $this->is_supported($child))
                {
                        $this->_adapter = $this->_backup_driver;
                }

                return $obj;
        }
        
        // ------------------------------------------------------------------------
}
// End Class

/* End of file Cache.php */
/* Location: ./system/libraries/Cache/Cache.php */