EventManager.php

<?php

/*
 *  $Id$
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the MIT license. For more information, see
 * <http://www.doctrine-project.org>.
 */
namespace Doctrine\Common;


/**
 * The EventManager is the central point of Doctrine's event listener system.
 * Listeners are registered on the manager and events are dispatched through the
 * manager.
 *
 * @license http://www.opensource.org/licenses/lgpl-license.php LGPL
 * @link    www.doctrine-project.org
 * @since   2.0
 * @version $Revision: 3938 $
 * @author  Guilherme Blanco <guilhermeblanco@hotmail.com>
 * @author  Jonathan Wage <jonwage@gmail.com>
 * @author  Roman Borschel <roman@code-factory.org>
 */
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);
  }

}