EventDispatcherInterface.php

<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */
namespace Symfony\Component\EventDispatcher;


/**
 * The EventDispatcherInterface is the central point of Symfony's event listener system.
 * Listeners are registered on the manager and events are dispatched through the
 * manager.
 *
 * @author Bernhard Schussek <bschussek@gmail.com>
 *
 * @api
 */
interface EventDispatcherInterface {

  /**
   * Dispatches an event to all registered listeners.
   *
   * @param string $eventName The name of the event to dispatch. The name of
   *                          the event is the name of the method that is
   *                          invoked on listeners.
   * @param Event $event The event to pass to the event handlers/listeners.
   *                          If not supplied, an empty Event instance is created.
   *
   * @return Event
   *
   * @api
   */
  public function dispatch($eventName, Event $event = null);

  /**
   * Adds an event listener that listens on the specified events.
   *
   * @param string   $eventName The event to listen on
   * @param callable $listener  The listener
   * @param integer  $priority  The higher this value, the earlier an event
   *                            listener will be triggered in the chain (defaults to 0)
   *
   * @api
   */
  public function addListener($eventName, $listener, $priority = 0);

  /**
   * Adds an event subscriber.
   *
   * The subscriber is asked for all the events he is
   * interested in and added as a listener for these events.
   *
   * @param EventSubscriberInterface $subscriber The subscriber.
   *
   * @api
   */
  public function addSubscriber(EventSubscriberInterface $subscriber);

  /**
   * Removes an event listener from the specified events.
   *
   * @param string|array $eventName The event(s) to remove a listener from
   * @param callable     $listener  The listener to remove
   */
  public function removeListener($eventName, $listener);

  /**
   * Removes an event subscriber.
   *
   * @param EventSubscriberInterface $subscriber The subscriber
   */
  public function removeSubscriber(EventSubscriberInterface $subscriber);

  /**
   * Gets the listeners of a specific event or all listeners.
   *
   * @param string $eventName The name of the event
   *
   * @return array The event listeners for the specified event, or all event listeners by event name
   */
  public function getListeners($eventName = null);

  /**
   * Checks whether an event has any registered listeners.
   *
   * @param string $eventName The name of the event
   *
   * @return Boolean true if the specified event has any listeners, false otherwise
   */
  public function hasListeners($eventName = null);

}