Add a plugin/event/hook system

lib/Resque/Event.php

@@ -0,0 +1,89 @@
+<?php
+/**
+ * Resque event/plugin system class
+ *
+ * @package		Resque/Event
+ * @author		Chris Boulton <chris.boulton@interspire.com>
+ * @copyright	(c) 2010 Chris Boulton
+ * @license		http://www.opensource.org/licenses/mit-license.php
+ */
+class Resque_Event
+{
+	/**
+	 * @var array Array containing all registered callbacks, indexked by event name.
+	 */
+	private static $events = array();
+
+	/**
+	 * Raise a given event with the supplied data.
+	 *
+	 * @param string $event Name of event to be raised.
+	 * @param mixed $data Optional, any data that should be passed to each callback.
+	 * @return true
+	 */
+	public static function trigger($event, $data = null)
+	{
+		if (!is_array($data)) {
+			$data = array($data);
+		}
+
+		if (empty(self::$events[$event])) {
+			return true;
+		}
+		
+		foreach (self::$events[$event] as $callback) {
+			if (!is_callable($callback)) {
+				continue;
+			}
+			call_user_func_array($callback, $data);
+		}
+		
+		return true;
+	}
+	
+	/**
+	 * Listen in on a given event to have a specified callback fired.
+	 *
+	 * @param string $event Name of event to listen on.
+	 * @param mixed $callback Any callback callable by call_user_func_array.
+	 * @return true
+	 */
+	public static function listen($event, $callback)
+	{
+		if (!isset(self::$events[$event])) {
+			self::$events[$event] = array();
+		}
+		
+		self::$events[$event][] = $callback;
+		return true;
+	}
+	
+	/**
+	 * Stop a given callback from listening on a specific event.
+	 *
+	 * @param string $event Name of event.
+	 * @param mixed $callback The callback as defined when listen() was called.
+	 * @return true
+	 */
+	public static function stopListening($event, $callback)
+	{
+		if (!isset(self::$events[$event])) {
+			return true;
+		}
+		
+		$key = array_search($callback, self::$events[$event]);
+		if ($key !== false) {
+			unset(self::$events[$key]);
+		}
+		
+		return true;
+	}
+	
+	/**
+	 * Call all registered listeners.
+	 */
+	public static function clearListeners()
+	{
+		self::$events = array();
+	}
+}