1<?php
2
3/*
4 * This file is part of the Symfony package.
5 *
6 * (c) Fabien Potencier <fabien@symfony.com>
7 *
8 * For the full copyright and license information, please view the LICENSE
9 * file that was distributed with this source code.
10 */
11
12namespace Symfony\Component\EventDispatcher;
13
14/**
15 * The EventDispatcherInterface is the central point of Symfony's event listener system.
16 * Listeners are registered on the manager and events are dispatched through the
17 * manager.
18 *
19 * @author Bernhard Schussek <bschussek@gmail.com>
20 *
21 * @api
22 */
23interface EventDispatcherInterface
24{
25    /**
26     * Dispatches an event to all registered listeners.
27     *
28     * @param string $eventName The name of the event to dispatch. The name of
29     *                          the event is the name of the method that is
30     *                          invoked on listeners.
31     * @param Event  $event     The event to pass to the event handlers/listeners.
32     *                          If not supplied, an empty Event instance is created.
33     *
34     * @return Event
35     *
36     * @api
37     */
38    public function dispatch($eventName, Event $event = null);
39
40    /**
41     * Adds an event listener that listens on the specified events.
42     *
43     * @param string   $eventName The event to listen on
44     * @param callable $listener  The listener
45     * @param int      $priority  The higher this value, the earlier an event
46     *                            listener will be triggered in the chain (defaults to 0)
47     *
48     * @api
49     */
50    public function addListener($eventName, $listener, $priority = 0);
51
52    /**
53     * Adds an event subscriber.
54     *
55     * The subscriber is asked for all the events he is
56     * interested in and added as a listener for these events.
57     *
58     * @param EventSubscriberInterface $subscriber The subscriber.
59     *
60     * @api
61     */
62    public function addSubscriber(EventSubscriberInterface $subscriber);
63
64    /**
65     * Removes an event listener from the specified events.
66     *
67     * @param string   $eventName The event to remove a listener from
68     * @param callable $listener  The listener to remove
69     */
70    public function removeListener($eventName, $listener);
71
72    /**
73     * Removes an event subscriber.
74     *
75     * @param EventSubscriberInterface $subscriber The subscriber
76     */
77    public function removeSubscriber(EventSubscriberInterface $subscriber);
78
79    /**
80     * Gets the listeners of a specific event or all listeners sorted by descending priority.
81     *
82     * @param string $eventName The name of the event
83     *
84     * @return array The event listeners for the specified event, or all event listeners by event name
85     */
86    public function getListeners($eventName = null);
87
88    /**
89     * Checks whether an event has any registered listeners.
90     *
91     * @param string $eventName The name of the event
92     *
93     * @return bool true if the specified event has any listeners, false otherwise
94     */
95    public function hasListeners($eventName = null);
96}
97