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<?php defined('SYSPATH') or die('No direct script access.');
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/**
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* Process queuing/execution class. Allows an unlimited number of callbacks
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* to be added to 'events'. Events can be run multiple times, and can also
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* process event-specific data. By default, Kohana has several system events.
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*
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* $Id: Event.php 1932 2008-02-05 22:57:19Z Shadowhand $
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*
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* @package Core
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* @author Kohana Team
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* @copyright (c) 2007 Kohana Team
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* @license http://kohanaphp.com/license.html
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* @link http://doc.kohanaphp.com/core/event
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*/
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final class Event {
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// Event callbacks
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private static $events = array();
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// Cache of events that have been run
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private static $has_run = array();
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// Data that can be processed during events
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public static $data;
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/**
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* Add a callback to an event queue.
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*
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* @param string event name
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* @param array http://php.net/callback
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* @return boolean
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*/
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public static function add($name, $callback)
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{
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if (empty($name) OR empty($callback))
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return FALSE;
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if ( ! isset(self::$events[$name]))
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{
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// Create an empty event if it is not yet defined
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self::$events[$name] = array();
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}
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if ( ! in_array($callback, self::$events[$name], TRUE))
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{
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// Add the event if it does not already exist in the queue
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self::$events[$name][] = $callback;
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}
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return TRUE;
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}
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/**
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* Add a callback to an event queue, before a given event.
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*
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* @param string event name
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* @param array existing event callback
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* @param array event callback
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* @return boolean
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*/
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public static function add_before($name, $existing, $callback)
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{
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if (empty($name) OR empty($existing) OR empty($callback))
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return FALSE;
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if (empty(self::$events[$name]) OR ($key = array_search($existing, self::$events[$name])) === FALSE)
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{
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// Just add the event if there are no events
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self::add($name, $callback);
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}
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else
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{
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// Insert the event immediately before the existing event
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self::insert_event($name, $key, $callback);
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}
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return TRUE;
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}
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/**
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* Add a callback to an event queue, after a given event.
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*
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* @param string event name
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* @param array existing event callback
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* @param array event callback
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* @return boolean
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*/
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public static function add_after($name, $existing, $callback)
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{
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if (empty($name) OR empty($existing) OR empty($callback))
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return FALSE;
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if (empty(self::$events[$name]) OR ($key = array_search($existing, self::$events[$name])) === FALSE)
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{
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// Just add the event if there are no events
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self::add($name, $callback);
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}
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else
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{
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// Insert the event immediately after the existing event
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self::insert_event($name, $key + 1, $callback);
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}
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return TRUE;
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}
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/**
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* Inserts a new event at a specfic key location.
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*
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* @param string event name
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* @param integer key to insert new event at
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* @param array event callback
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* @return void
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*/
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private static function insert_event($name, $key, $callback)
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{
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// Add the new event at the given key location
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self::$events[$name] = array_merge
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(
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// Events before the key
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array_slice(self::$events[$name], 0, $key),
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// New event callback
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array($callback),
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// Events after the key
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array_slice(self::$events[$name], $key)
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);
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}
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/**
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* Replaces an event with another event.
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*
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* @param string event name
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* @param array event to replace
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* @param array new callback
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* @return boolean
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*/
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public static function replace($name, $existing, $callback)
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{
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if (empty($name) OR empty($existing) OR empty($callback) OR empty(self::$events[$name]))
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return FALSE;
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if (($key = array_search($existing, self::$events[$name], TRUE)) === FALSE)
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return FALSE;
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if ( ! in_array($callback, self::$events[$name], TRUE))
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{
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// Replace the exisiting event with the new event
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self::$events[$name][$key] = $callback;
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}
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else
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{
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// Remove the existing event from the queue
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unset(self::$events[$name][$key]);
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// Reset the array so the keys are ordered properly
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self::$events[$name] = array_values(self::$events[$name]);
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}
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return TRUE;
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}
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/**
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* Get all callbacks for an event.
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*
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* @param string event name
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* @return array
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*/
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public static function get($name)
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{
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return empty(self::$events[$name]) ? array() : self::$events[$name];
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}
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/**
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* Clear some or all callbacks from an event.
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*
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* @param string event name
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* @param array specific callback to remove, FALSE for all callbacks
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* @return void
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*/
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public static function clear($name, $callback = FALSE)
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{
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if ($callback == FALSE)
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{
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self::$events[$name] = array();
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}
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elseif (isset(self::$events[$name]))
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{
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// Loop through each of the event callbacks and compare it to the
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// callback requested for removal. The callback is removed if it
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// matches.
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foreach(self::$events[$name] as $i => $event_callback)
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{
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if ($callback === $event_callback)
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{
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unset(self::$events[$name][$i]);
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}
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}
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}
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}
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/**
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* Execute all of the callbacks attached to an event.
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*
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* @param string event name
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* @param array data can be processed as Event::$data by the callbacks
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* @return void
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*/
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public static function run($name, & $data = NULL)
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{
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if ( ! empty(self::$events[$name]))
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{
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// So callbacks can access Event::$data
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self::$data =& $data;
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foreach(self::get($name) as $callback)
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{
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call_user_func($callback);
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}
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// Do this to prevent data from getting 'stuck'
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$clear_data = '';
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self::$data =& $clear_data;
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// The event has been run!
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self::$has_run[$name] = $name;
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}
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}
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/**
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* Check if a given event has been run.
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*
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* @param string event name
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* @return boolean
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*/
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public static function has_run($name)
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{
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return isset(self::$has_run[$name]);
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}
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} // End Event
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