<?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 LGPL. For more information, see

 * <http://www.doctrine-project.org>.

 */

namespace Doctrine\Common;

use Doctrine\Common\Events\Event;

/**

 * 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);

    }

}