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<?php defined('SYSPATH') OR die('No direct access allowed.');
/**
* Process queuing/execution class. Allows an unlimited number of callbacks
* to be added to 'events'. Events can be run multiple times, and can also
* process event-specific data. By default, Kohana has several system events.
*
* $Id: Event.php 3993 2009-02-17 18:42:50Z jheathco $
*
* @package Core
* @author Kohana Team
* @copyright (c) 2007 Kohana Team
* @license http://kohanaphp.com/license.html
* @link http://docs.kohanaphp.com/general/events
*/
final class Event {
// Event callbacks
private static $events = array();
// Cache of events that have been run
private static $has_run = array();
// Data that can be processed during events
public static $data;
/**
* Add a callback to an event queue.
*
* @param string event name
* @param array http://php.net/callback
* @return boolean
*/
public static function add($name, $callback)
{
if ( ! isset(self::$events[$name]))
{
// Create an empty event if it is not yet defined
self::$events[$name] = array();
}
elseif (in_array($callback, self::$events[$name], TRUE))
{
// The event already exists
return FALSE;
}
// Add the event
self::$events[$name][] = $callback;
return TRUE;
}
/**
* Add a callback to an event queue, before a given event.
*
* @param string event name
* @param array existing event callback
* @param array event callback
* @return boolean
*/
public static function add_before($name, $existing, $callback)
{
if (empty(self::$events[$name]) OR ($key = array_search($existing, self::$events[$name])) === FALSE)
{
// Just add the event if there are no events
return self::add($name, $callback);
}
else
{
// Insert the event immediately before the existing event
return self::insert_event($name, $key, $callback);
}
}
/**
* Add a callback to an event queue, after a given event.
*
* @param string event name
* @param array existing event callback
* @param array event callback
* @return boolean
*/
public static function add_after($name, $existing, $callback)
{
if (empty(self::$events[$name]) OR ($key = array_search($existing, self::$events[$name])) === FALSE)
{
// Just add the event if there are no events
return self::add($name, $callback);
}
else
{
// Insert the event immediately after the existing event
return self::insert_event($name, $key + 1, $callback);
}
}
/**
* Inserts a new event at a specfic key location.
*
* @param string event name
* @param integer key to insert new event at
* @param array event callback
* @return void
*/
private static function insert_event($name, $key, $callback)
{
if (in_array($callback, self::$events[$name], TRUE))
return FALSE;
// Add the new event at the given key location
self::$events[$name] = array_merge
(
// Events before the key
array_slice(self::$events[$name], 0, $key),
// New event callback
array($callback),
// Events after the key
array_slice(self::$events[$name], $key)
);
return TRUE;
}
/**
* Replaces an event with another event.
*
* @param string event name
* @param array event to replace
* @param array new callback
* @return boolean
*/
public static function replace($name, $existing, $callback)
{
if (empty(self::$events[$name]) OR ($key = array_search($existing, self::$events[$name], TRUE)) === FALSE)
return FALSE;
if ( ! in_array($callback, self::$events[$name], TRUE))
{
// Replace the exisiting event with the new event
self::$events[$name][$key] = $callback;
}
else
{
// Remove the existing event from the queue
unset(self::$events[$name][$key]);
// Reset the array so the keys are ordered properly
self::$events[$name] = array_values(self::$events[$name]);
}
return TRUE;
}
/**
* Get all callbacks for an event.
*
* @param string event name
* @return array
*/
public static function get($name)
{
return empty(self::$events[$name]) ? array() : self::$events[$name];
}
/**
* Clear some or all callbacks from an event.
*
* @param string event name
* @param array specific callback to remove, FALSE for all callbacks
* @return void
*/
public static function clear($name, $callback = FALSE)
{
if ($callback === FALSE)
{
self::$events[$name] = array();
}
elseif (isset(self::$events[$name]))
{
// Loop through each of the event callbacks and compare it to the
// callback requested for removal. The callback is removed if it
// matches.
foreach (self::$events[$name] as $i => $event_callback)
{
if ($callback === $event_callback)
{
unset(self::$events[$name][$i]);
}
}
}
}
/**
* Execute all of the callbacks attached to an event.
*
* @param string event name
* @param array data can be processed as Event::$data by the callbacks
* @return void
*/
public static function run($name, & $data = NULL)
{
if ( ! empty(self::$events[$name]))
{
// So callbacks can access Event::$data
self::$data =& $data;
$callbacks = self::get($name);
foreach ($callbacks as $callback)
{
call_user_func($callback);
}
// Do this to prevent data from getting 'stuck'
$clear_data = '';
self::$data =& $clear_data;
}
// The event has been run!
self::$has_run[$name] = $name;
}
/**
* Check if a given event has been run.
*
* @param string event name
* @return boolean
*/
public static function has_run($name)
{
return isset(self::$has_run[$name]);
}
} // End Event
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