<?php
/**
 * @package     Joomla.Platform
 * @subpackage  Registry
 *
 * @copyright   Copyright (C) 2005 - 2011 Open Source Matters, Inc. All rights reserved.
 * @license     GNU General Public License version 2 or later; see LICENSE
 */

defined('JPATH_PLATFORM') or die;

/**
 * Abstract Format for JRegistry
 *
 * @abstract
 * @package     Joomla.Platform
 * @subpackage  Registry
 * @since       11.1
 */
abstract class JRegistryFormat
{
    /**
     * Returns a reference to a Format object, only creating it
     * if it doesn't already exist.
     *
     * @param   string  The format to load
     * @return  object  Registry format handler
     * @throws  JException
     * @since   11.1
     */
    public static function getInstance($type)
    {
        // Initialize static variable.
        static $instances;
        if (!isset ($instances)) {
            $instances = array ();
        }

        // Sanitize format type.
        $type = strtolower(preg_replace('/[^A-Z0-9_]/i', '', $type));

        // Only instantiate the object if it doesn't already exist.
        if (!isset($instances[$type])) {
            // Only load the file the class does not exist.
            $class = 'JRegistryFormat'.$type;
            if (!class_exists($class)) {
                $path = dirname(__FILE__).'/format/'.$type.'.php';
                if (is_file($path)) {
                    require_once $path;
                } else {
                    throw new JException(JText::_('JLIB_REGISTRY_EXCEPTION_LOAD_FORMAT_CLASS'), 500, E_ERROR);
                }
            }

            $instances[$type] = new $class();
        }
        return $instances[$type];
    }

    /**
     * Converts an object into a formatted string.
     *
     * @param   object  Data Source Object.
     * @param   array   An array of options for the formatter.
     * @return  string  Formatted string.
     * @since   11.1
     */
    abstract public function objectToString($object, $options = null);

    /**
     * Converts a formatted string into an object.
     *
     * @param   string  Formatted string
     * @param   array   An array of options for the formatter.
     * @return  object  Data Object
     * @since   11.1
     */
    abstract public function stringToObject($data, $options = null);
}