1<?php
2namespace Doctrine\Common;
3
4use function spl_object_hash;
5
6/**
7 * The EventManager is the central point of Doctrine's event listener system.
8 * Listeners are registered on the manager and events are dispatched through the
9 * manager.
10 */
11class EventManager
12{
13    /**
14     * Map of registered listeners.
15     * <event> => <listeners>
16     *
17     * @var object[][]
18     */
19    private $_listeners = [];
20
21    /**
22     * Dispatches an event to all registered listeners.
23     *
24     * @param string         $eventName The name of the event to dispatch. The name of the event is
25     *                                  the name of the method that is invoked on listeners.
26     * @param EventArgs|null $eventArgs The event arguments to pass to the event handlers/listeners.
27     *                                  If not supplied, the single empty EventArgs instance is used.
28     *
29     * @return void
30     */
31    public function dispatchEvent($eventName, ?EventArgs $eventArgs = null)
32    {
33        if (! isset($this->_listeners[$eventName])) {
34            return;
35        }
36
37        $eventArgs = $eventArgs ?? EventArgs::getEmptyInstance();
38
39        foreach ($this->_listeners[$eventName] as $listener) {
40            $listener->$eventName($eventArgs);
41        }
42    }
43
44    /**
45     * Gets the listeners of a specific event or all listeners.
46     *
47     * @param string|null $event The name of the event.
48     *
49     * @return object[]|object[][] The event listeners for the specified event, or all event listeners.
50     */
51    public function getListeners($event = null)
52    {
53        return $event ? $this->_listeners[$event] : $this->_listeners;
54    }
55
56    /**
57     * Checks whether an event has any registered listeners.
58     *
59     * @param string $event
60     *
61     * @return bool TRUE if the specified event has any listeners, FALSE otherwise.
62     */
63    public function hasListeners($event)
64    {
65        return ! empty($this->_listeners[$event]);
66    }
67
68    /**
69     * Adds an event listener that listens on the specified events.
70     *
71     * @param string|string[] $events   The event(s) to listen on.
72     * @param object          $listener The listener object.
73     *
74     * @return void
75     */
76    public function addEventListener($events, $listener)
77    {
78        // Picks the hash code related to that listener
79        $hash = spl_object_hash($listener);
80
81        foreach ((array) $events as $event) {
82            // Overrides listener if a previous one was associated already
83            // Prevents duplicate listeners on same event (same instance only)
84            $this->_listeners[$event][$hash] = $listener;
85        }
86    }
87
88    /**
89     * Removes an event listener from the specified events.
90     *
91     * @param string|string[] $events
92     * @param object          $listener
93     *
94     * @return void
95     */
96    public function removeEventListener($events, $listener)
97    {
98        // Picks the hash code related to that listener
99        $hash = spl_object_hash($listener);
100
101        foreach ((array) $events as $event) {
102            unset($this->_listeners[$event][$hash]);
103        }
104    }
105
106    /**
107     * Adds an EventSubscriber. The subscriber is asked for all the events it is
108     * interested in and added as a listener for these events.
109     *
110     * @param EventSubscriber $subscriber The subscriber.
111     *
112     * @return void
113     */
114    public function addEventSubscriber(EventSubscriber $subscriber)
115    {
116        $this->addEventListener($subscriber->getSubscribedEvents(), $subscriber);
117    }
118
119    /**
120     * Removes an EventSubscriber. The subscriber is asked for all the events it is
121     * interested in and removed as a listener for these events.
122     *
123     * @param EventSubscriber $subscriber The subscriber.
124     *
125     * @return void
126     */
127    public function removeEventSubscriber(EventSubscriber $subscriber)
128    {
129        $this->removeEventListener($subscriber->getSubscribedEvents(), $subscriber);
130    }
131}
132