<?php namespace Sabre\Event; /** * Event Emitter Interface * * Anything that accepts listeners and emits events should implement this * interface. * * @copyright Copyright (C) 2013-2015 fruux GmbH (https://fruux.com/). * @author Evert Pot (http://evertpot.com/) * @license http://sabre.io/license/ Modified BSD License */ interface EventEmitterInterface { /** * Subscribe to an event. * * @param string $eventName * @param callable $callBack * @param int $priority * @return void */ function on($eventName, callable $callBack, $priority = 100); /** * Subscribe to an event exactly once. * * @param string $eventName * @param callable $callBack * @param int $priority * @return void */ function once($eventName, callable $callBack, $priority = 100); /** * Emits an event. * * This method will return true if 0 or more listeners were succesfully * handled. false is returned if one of the events broke the event chain. * * If the continueCallBack is specified, this callback will be called every * time before the next event handler is called. * * If the continueCallback returns false, event propagation stops. This * allows you to use the eventEmitter as a means for listeners to implement * functionality in your application, and break the event loop as soon as * some condition is fulfilled. * * Note that returning false from an event subscriber breaks propagation * and returns false, but if the continue-callback stops propagation, this * is still considered a 'successful' operation and returns true. * * Lastly, if there are 5 event handlers for an event. The continueCallback * will be called at most 4 times. * * @param string $eventName * @param array $arguments * @param callback $continueCallBack * @return bool */ function emit($eventName, array $arguments = [], callable $continueCallBack = null); /** * Returns the list of listeners for an event. * * The list is returned as an array, and the list of events are sorted by * their priority. * * @param string $eventName * @return callable[] */ function listeners($eventName); /** * Removes a specific listener from an event. * * If the listener could not be found, this method will return false. If it * was removed it will return true. * * @param string $eventName * @param callable $listener * @return bool */ function removeListener($eventName, callable $listener); /** * Removes all listeners. * * If the eventName argument is specified, all listeners for that event are * removed. If it is not specified, every listener for every event is * removed. * * @param string $eventName * @return void */ function removeAllListeners($eventName = null); }