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 */
21interface EventDispatcherInterface
22{
23    /**
24     * Dispatches an event to all registered listeners.
25     *
26     * @param string     $eventName The name of the event to dispatch. The name of
27     *                              the event is the name of the method that is
28     *                              invoked on listeners.
29     * @param Event|null $event     The event to pass to the event handlers/listeners
30     *                              If not supplied, an empty Event instance is created
31     *
32     * @return Event
33     */
34    public function dispatch($eventName, Event $event = null);
35
36    /**
37     * Adds an event listener that listens on the specified events.
38     *
39     * @param string   $eventName The event to listen on
40     * @param callable $listener  The listener
41     * @param int      $priority  The higher this value, the earlier an event
42     *                            listener will be triggered in the chain (defaults to 0)
43     */
44    public function addListener($eventName, $listener, $priority = 0);
45
46    /**
47     * Adds an event subscriber.
48     *
49     * The subscriber is asked for all the events it is
50     * interested in and added as a listener for these events.
51     */
52    public function addSubscriber(EventSubscriberInterface $subscriber);
53
54    /**
55     * Removes an event listener from the specified events.
56     *
57     * @param string   $eventName The event to remove a listener from
58     * @param callable $listener  The listener to remove
59     */
60    public function removeListener($eventName, $listener);
61
62    public function removeSubscriber(EventSubscriberInterface $subscriber);
63
64    /**
65     * Gets the listeners of a specific event or all listeners sorted by descending priority.
66     *
67     * @param string|null $eventName The name of the event
68     *
69     * @return array The event listeners for the specified event, or all event listeners by event name
70     */
71    public function getListeners($eventName = null);
72
73    /**
74     * Gets the listener priority for a specific event.
75     *
76     * Returns null if the event or the listener does not exist.
77     *
78     * @param string   $eventName The name of the event
79     * @param callable $listener  The listener
80     *
81     * @return int|null The event listener priority
82     */
83    public function getListenerPriority($eventName, $listener);
84
85    /**
86     * Checks whether an event has any registered listeners.
87     *
88     * @param string|null $eventName The name of the event
89     *
90     * @return bool true if the specified event has any listeners, false otherwise
91     */
92    public function hasListeners($eventName = null);
93}
94