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Diffstat (limited to 'lib/classes/NotificationCenter.php')
| -rw-r--r-- | lib/classes/NotificationCenter.php | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/lib/classes/NotificationCenter.php b/lib/classes/NotificationCenter.php new file mode 100644 index 0000000..178fd62 --- /dev/null +++ b/lib/classes/NotificationCenter.php @@ -0,0 +1,174 @@ +<?php +# Lifter010: TODO +/* + * NotificationCenter.php - NotificationCenter class + * + * Copyright (c) 2009 Elmar Ludwig + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + */ + +// ######################################################################## +// MODULE DEFINITION +/** @defgroup notifications Notifications */ + +/** + * Special Exception that can be thrown to veto an announced change. + * Only some types of events support this (see documentation). + */ +class NotificationVetoException extends Exception +{ +} + +/** + * The NotificationCenter class is the central event dispatcher + * for Stud.IP. Objects interested in receiving notifications for + * particular events need to register with the NotificationCenter: + * + * NotificationCenter::addObserver($this, 'update', 'shutdown'); + * + * Event notifications are sent via the postNotification() method: + * + * NotificationCenter::postNotification('shutdown', $sender); + */ +class NotificationCenter +{ + /** + * array of registered notification observers + */ + private static $observers = []; + + /** + * Register an object to be notified. The same object may be + * registered several times (e.g. for different notifications). + * The event name may contain shell-style wildcards (like '*'). + * + * @param object $observer object to be notified + * @param string $method method that will be called + * @param string $event name of event (may be NULL) + * @param mixed $object subject to observe (may be NULL) + */ + public static function addObserver($observer, $method, $event, $object = NULL) + { + if ($event === NULL) { + $event = ''; + } + + $predicate = null; + + if ($object) { + $predicate = is_callable($object) + ? $object + : function ($other) use ($object) { + return $object === $other; + }; + } + + self::$observers[$event][] = [ + 'predicate' => $predicate, + 'observer' => [$observer, $method] + ]; + } + + /** + * Remove an object registered with the NotificationCenter. + * Trying to remove an observer that was not registered is + * allowed and has no effect. + * + * @param object $observer object to be removed + * @param string $event name of event (may be NULL) + * @param mixed $object subject to observe (may be NULL) + */ + public static function removeObserver($observer, $event = NULL, $object = NULL) + { + if ($event === NULL) { + $events = array_keys(self::$observers); + } else if (isset(self::$observers[$event])) { + $events = [$event]; + } else { + return; + } + + foreach ($events as $event) { + foreach (self::$observers[$event] as $index => $list) { + if ($object === NULL + || $list['predicate'] && $list['predicate']($object)) { + + if ($list['observer'][0] === $observer) { + unset(self::$observers[$event][$index]); + } + } + } + } + } + + /** + * Post an event notification to all registered observers. + * Only observers registered for this event type and subject + * are notified. + * + * @param string $event name of this notification + * @param mixed $object subject of this notification + * @param mixed $user_data additional information (optional) + * + * @throws NotificationVetoException on observer veto + */ + public static function postNotification($event, $object, $user_data = null) + { + $current_observers = []; + foreach (self::$observers as $e => $l) { + if ($e === '' || fnmatch($e, $event, FNM_NOESCAPE)) { + $current_observers = array_merge($current_observers, $l); + } + } + + foreach ($current_observers as $list) { + if (!$list['predicate'] || $list['predicate']($object)) { + call_user_func($list['observer'], $event, $object, $user_data); + } + } + } + + /** + * Convenience method that uses a jQuery like structure for event + * registration by closures. + * + * @param string $event + * @param Callable $callback + * @param mixed $object + * @since Stud.IP 4.2 + */ + public static function on($event, Callable $callback, $object = null) + { + if ($callback instanceof Closure || is_object($callback)) { + static::addObserver($callback, '__invoke', $event, $object); + } elseif (is_array($callback)) { + static::addObserver($callback[0], $callback[1], $event, $object); + } elseif (is_string($callback)) { + throw new Exception('Strings as callable may not be passed to ' . __METHOD__); + } + } + + /** + * Convenience method that uses a jQuery like structure for event + * unregistration by closures. + * + * @param string $event + * @param Callable $callback + * @param mixed $object + * @since Stud.IP 4.2 + */ + public static function off($event, Callable $callback, $object = null) + { + if ($callback instanceof Closure || is_object($callback)) { + static::removeObserver($callback, $event, $object); + } elseif (is_array($callback)) { + static::removeObserver($callback[0], $event, $object); + } elseif (is_string($callback)) { + throw new Exception('Strings as callable may not be passed to ' . __METHOD__); + } + } +} |