class EventManager

EventManagerTest.php in drupal/core/vendor/doctrine/common/tests/Doctrine/Tests/Common/EventManagerTest.php

class EventManager {

  /**
   * Map of registered listeners.
   * <event> => <listeners>
   *
   * @var array
   */
  private $_listeners = array();

  /**
   * 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 EventArgs $eventArgs The event arguments to pass to the event handlers/listeners.
   *                             If not supplied, the single empty EventArgs instance is used.
   * @return boolean
   */
  public function dispatchEvent($eventName, EventArgs $eventArgs = null) {
    if (isset($this->_listeners[$eventName])) {
      $eventArgs = $eventArgs === null ? EventArgs::getEmptyInstance() : $eventArgs;
      foreach ($this->_listeners[$eventName] as $listener) {
        $listener
          ->{$eventName}($eventArgs);
      }
    }
  }

  /**
   * Gets the listeners of a specific event or all listeners.
   *
   * @param string $event The name of the event.
   * @return array The event listeners for the specified event, or all event listeners.
   */
  public function getListeners($event = null) {
    return $event ? $this->_listeners[$event] : $this->_listeners;
  }

  /**
   * Checks whether an event has any registered listeners.
   *
   * @param string $event
   * @return boolean TRUE if the specified event has any listeners, FALSE otherwise.
   */
  public function hasListeners($event) {
    return isset($this->_listeners[$event]) && $this->_listeners[$event];
  }

  /**
   * Adds an event listener that listens on the specified events.
   *
   * @param string|array $events The event(s) to listen on.
   * @param object $listener The listener object.
   */
  public function addEventListener($events, $listener) {

    // Picks the hash code related to that listener
    $hash = spl_object_hash($listener);
    foreach ((array) $events as $event) {

      // Overrides listener if a previous one was associated already
      // Prevents duplicate listeners on same event (same instance only)
      $this->_listeners[$event][$hash] = $listener;
    }
  }

  /**
   * Removes an event listener from the specified events.
   *
   * @param string|array $events
   * @param object $listener
   */
  public function removeEventListener($events, $listener) {

    // Picks the hash code related to that listener
    $hash = spl_object_hash($listener);
    foreach ((array) $events as $event) {

      // Check if actually have this listener associated
      if (isset($this->_listeners[$event][$hash])) {
        unset($this->_listeners[$event][$hash]);
      }
    }
  }

  /**
   * Adds an EventSubscriber. The subscriber is asked for all the events he is
   * interested in and added as a listener for these events.
   *
   * @param \Doctrine\Common\EventSubscriber $subscriber The subscriber.
   */
  public function addEventSubscriber(EventSubscriber $subscriber) {
    $this
      ->addEventListener($subscriber
      ->getSubscribedEvents(), $subscriber);
  }

  /**
   * Removes an EventSubscriber. The subscriber is asked for all the events it is
   * interested in and removed as a listener for these events.
   *
   * @param \Doctrine\Common\EventSubscriber $subscriber The subscriber.
   */
  public function removeEventSubscriber(EventSubscriber $subscriber) {
    $this
      ->removeEventListener($subscriber
      ->getSubscribedEvents(), $subscriber);
  }

}