<?php
/**
 * File containing the ezcCacheStackableStorage class.
 *
 * @package Cache
 * @version 1.4beta1
 * @copyright Copyright (C) 2005-2008 eZ systems as. All rights reserved.
 * @license http://ez.no/licenses/new_bsd New BSD License
 * @filesource
 */

/**
 * Interface for stackable storage classes.
 * 
 * This interface must be implemented by storages that can be combined into a
 * {@link ezcCacheStack}.
 *
 * @package Cache
 * @version 1.4beta1
 */
interface ezcCacheStackableStorage
{
    /**
     * Purge outdated data from the storage. 
     * 
     * This method purges outdated data from the cache. If $limit is given, a
     * maximum of $limit items is purged. Otherwise all outdated items are
     * purged. The method returns an array containing the IDs of all cache
     * items that have been purged.
     *
     * @param int $limit 
     * @return array(string)
     */
    public function purge( $limit = null );


    /**
     * Delete data from the cache.
     *
     * This method is already defined in {@link ezcCacheStorage::delete()}.
     * However, the basic definition does not define a return value. If this
     * interface is implemented, the method must return an array of item IDs
     * that have been deleted from the storage.
     *
     * @param string $id
     * @param array(string=>string)
     * @param bool $search
     *
     * @return array(string)
     */
    // @TODO: Does not work since this method is already declared abstract in
    // ezcCacheStorage. "Fatal error: Can't inherit abstract function..." in
    // 5.2.6RC3-dev
    // public function delete( $id = null, $attributes = array(), $search = false );

    /**
     * Reset the complete storage.
     *
     * This method resets the complete cache storage. All content (including
     * content stored with the {@link ezcCacheStackMetaDataStorage} interfacer) must
     * be deleted and the cache storage must appear as if it has just newly
     * been created.
     * 
     * @return void
     */
    public function reset();
}

?>