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<?php
/**
* @package Joomla.Platform
* @subpackage Event
*
* @copyright Copyright (C) 2005 - 2012 Open Source Matters, Inc. All rights reserved.
* @license GNU General Public License version 2 or later; see LICENSE
*/
defined('JPATH_PLATFORM') or die;
/**
* Class to handle dispatching of events.
*
* This is the Observable part of the Observer design pattern
* for the event architecture.
*
* @package Joomla.Platform
* @subpackage Event
* @link http://docs.joomla.org/Tutorial:Plugins Plugin tutorials
* @see JPlugin
* @since 12.1
*/
class JEventDispatcher extends JObject
{
/**
* An array of Observer objects to notify
*
* @var array
* @since 11.3
*/
protected $_observers = array();
/**
* The state of the observable object
*
* @var mixed
* @since 11.3
*/
protected $_state = null;
/**
* A multi dimensional array of [function][] = key for observers
*
* @var array
* @since 11.3
*/
protected $_methods = array();
/**
* Stores the singleton instance of the dispatcher.
*
* @var JEventDispatcher
* @since 11.3
*/
protected static $instance = null;
/**
* Returns the global Event Dispatcher object, only creating it
* if it doesn't already exist.
*
* @return JEventDispatcher The EventDispatcher object.
*
* @since 11.1
*/
public static function getInstance()
{
if (self::$instance === null)
{
self::$instance = new static;
}
return self::$instance;
}
/**
* Get the state of the JEventDispatcher object
*
* @return mixed The state of the object.
*
* @since 11.3
*/
public function getState()
{
return $this->_state;
}
/**
* Registers an event handler to the event dispatcher
*
* @param string $event Name of the event to register handler for
* @param string $handler Name of the event handler
*
* @return void
*
* @since 11.1
* @throws InvalidArgumentException
*/
public function register($event, $handler)
{
// Are we dealing with a class or callback type handler?
if (is_callable($handler))
{
// Ok, function type event handler... let's attach it.
$method = array('event' => $event, 'handler' => $handler);
$this->attach($method);
}
elseif (class_exists($handler))
{
// Ok, class type event handler... let's instantiate and attach it.
$this->attach(new $handler($this));
}
else
{
throw new InvalidArgumentException('Invalid event handler.');
}
}
/**
* Triggers an event by dispatching arguments to all observers that handle
* the event and returning their return values.
*
* @param string $event The event to trigger.
* @param array $args An array of arguments.
*
* @return array An array of results from each function call.
*
* @since 11.1
*/
public function trigger($event, $args = array())
{
$result = array();
/*
* If no arguments were passed, we still need to pass an empty array to
* the call_user_func_array function.
*/
$args = (array) $args;
$event = strtolower($event);
// Check if any plugins are attached to the event.
if (!isset($this->_methods[$event]) || empty($this->_methods[$event]))
{
// No Plugins Associated To Event!
return $result;
}
// Loop through all plugins having a method matching our event
foreach ($this->_methods[$event] as $key)
{
// Check if the plugin is present.
if (!isset($this->_observers[$key]))
{
continue;
}
// Fire the event for an object based observer.
if (is_object($this->_observers[$key]))
{
$args['event'] = $event;
$value = $this->_observers[$key]->update($args);
}
// Fire the event for a function based observer.
elseif (is_array($this->_observers[$key]))
{
$value = call_user_func_array($this->_observers[$key]['handler'], $args);
}
if (isset($value))
{
$result[] = $value;
}
}
return $result;
}
/**
* Attach an observer object
*
* @param object $observer An observer object to attach
*
* @return void
*
* @since 11.3
*/
public function attach($observer)
{
if (is_array($observer))
{
if (!isset($observer['handler']) || !isset($observer['event']) || !is_callable($observer['handler']))
{
return;
}
// Make sure we haven't already attached this array as an observer
foreach ($this->_observers as $check)
{
if (is_array($check) && $check['event'] == $observer['event'] && $check['handler'] == $observer['handler'])
{
return;
}
}
$this->_observers[] = $observer;
end($this->_observers);
$methods = array($observer['event']);
}
else
{
if (!($observer instanceof JEvent))
{
return;
}
// Make sure we haven't already attached this object as an observer
$class = get_class($observer);
foreach ($this->_observers as $check)
{
if ($check instanceof $class)
{
return;
}
}
$this->_observers[] = $observer;
$methods = array_diff(get_class_methods($observer), get_class_methods('JPlugin'));
}
$key = key($this->_observers);
foreach ($methods as $method)
{
$method = strtolower($method);
if (!isset($this->_methods[$method]))
{
$this->_methods[$method] = array();
}
$this->_methods[$method][] = $key;
}
}
/**
* Detach an observer object
*
* @param object $observer An observer object to detach.
*
* @return boolean True if the observer object was detached.
*
* @since 11.3
*/
public function detach($observer)
{
$retval = false;
$key = array_search($observer, $this->_observers);
if ($key !== false)
{
unset($this->_observers[$key]);
$retval = true;
foreach ($this->_methods as &$method)
{
$k = array_search($key, $method);
if ($k !== false)
{
unset($method[$k]);
}
}
}
return $retval;
}
}
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