<?php
/**
* Registry class
*
* $Id: Registry.php 157 2011-02-10 06:06:24Z indy $
*
* $LastChangedBy: indy $
*
* $LastChangedDate: 2011-02-10 08:06:24 +0200 (Thu, 10 Feb 2011) $
*
* $Rev: 157 $
*
* @author Indiana Jones <hide@address.com>
* @version 1.0
* @copyright 2010 PhpIndex
* @package PhpIndex
*/

/**
 * Generic storage class helps to manage global data.
 */
class PhpIndex_Registry extends ArrayObject
{
    /**
     * Registry object provides storage for shared objects.
     *
     * @var PhpIndex_Registry
     */
    protected static $_registry = null;

    /**
     * Constructs a parent ArrayObject with default
     * ARRAY_AS_PROPS to allow acces as an object
     *
     * @param array $array data array
     */
    public function __construct($array = array())
    {
        parent::__construct($array, parent::ARRAY_AS_PROPS);
    }

    /**
     * Retrieves the default registry instance.
     *
     * @return PhpIndex_Registry
     */
    public static function getInstance()
    {
        if (is_null(self::$_registry)) {
            self::_init();
        }

        return self::$_registry;
    }

    /**
     * Set the default registry instance to a specified instance.
     *
     * @param PhpIndex_Registry $registry An object instance of type PhpIndex_Registry,
     *   or a subclass.
     * @return void
     * @throws Exception if registry is already initialized.
     */
    public static function setInstance(PhpIndex_Registry $registry)
    {
        if (!is_null(self::$_registry)) {
            throw new Exception('Registry is already initialized');
        }

        self::$_registry = $registry;
    }

    /**
     * getter method, basically same as offsetGet().
     *
     * This method can be called from an object of type PhpIndex_Registry, or it
     * can be called statically.  In the latter case, it uses the default
     * static instance stored in the class.
     *
     * @param string $index - get the value associated with $index
     * @return mixed
     * @throws Exception if no entry is registerd for $index.
     */
    public static function get($index)
    {
        $instance = self::getInstance();

        if (!$instance->offsetExists($index)) {
            throw new Exception("No entry is registered for key '" . $index . "'");
        }

        return $instance->offsetGet($index);
    }

    /**
     * setter method, basically same as offsetSet().
     *
     * This method can be called from an object of type PhpIndex_Registry, or it
     * can be called statically.  In the latter case, it uses the default
     * static instance stored in the class.
     *
     * @param string $index The location in the ArrayObject in which to store
     *   the value.
     * @param mixed $value The object to store in the ArrayObject.
     * @return void
     */
    public static function set($index, $value)
    {
        $instance = self::getInstance();
        $instance->offsetSet($index, $value);
    }

    /**
     * Returns TRUE if the $index is a named value in the registry,
     * or FALSE if $index was not found in the registry.
     *
     * @param  string $index
     * @return boolean
     */
    public static function isRegistered($index)
    {
        if (self::$_registry === null) {
            return false;
        }
        return self::$_registry->offsetExists($index);
    }

    /**
     * Check if an offset exists
     *
     * @param string $index
     * @returns mixed
     */
    public function offsetExists($index)
    {
        return array_key_exists($index, $this);
    }

    /**
     * Initialize the default registry instance.
     *
     * @return void
     */
    protected static function _init()
    {
        self::setInstance(new PhpIndex_Registry());
    }
}

/* EOF */