1<?php
2
3namespace Doctrine\Common;
4
5use function spl_object_hash;
6
7/**
8 * The EventManager is the central point of Doctrine's event listener system.
9 * Listeners are registered on the manager and events are dispatched through the
10 * manager.
11 */
12class EventManager
13{
14    /**
15     * Map of registered listeners.
16     * <event> => <listeners>
17     *
18     * @var object[][]
19     */
20    private $_listeners = [];
21
22    /**
23     * Dispatches an event to all registered listeners.
24     *
25     * @param string         $eventName The name of the event to dispatch. The name of the event is
26     *                                  the name of the method that is invoked on listeners.
27     * @param EventArgs|null $eventArgs The event arguments to pass to the event handlers/listeners.
28     *                                  If not supplied, the single empty EventArgs instance is used.
29     *
30     * @return void
31     */
32    public function dispatchEvent($eventName, ?EventArgs $eventArgs = null)
33    {
34        if (! isset($this->_listeners[$eventName])) {
35            return;
36        }
37
38        $eventArgs = $eventArgs ?? EventArgs::getEmptyInstance();
39
40        foreach ($this->_listeners[$eventName] as $listener) {
41            $listener->$eventName($eventArgs);
42        }
43    }
44
45    /**
46     * Gets the listeners of a specific event or all listeners.
47     *
48     * @param string|null $event The name of the event.
49     *
50     * @return object[]|object[][] The event listeners for the specified event, or all event listeners.
51     */
52    public function getListeners($event = null)
53    {
54        return $event ? $this->_listeners[$event] : $this->_listeners;
55    }
56
57    /**
58     * Checks whether an event has any registered listeners.
59     *
60     * @param string $event
61     *
62     * @return bool TRUE if the specified event has any listeners, FALSE otherwise.
63     */
64    public function hasListeners($event)
65    {
66        return ! empty($this->_listeners[$event]);
67    }
68
69    /**
70     * Adds an event listener that listens on the specified events.
71     *
72     * @param string|string[] $events   The event(s) to listen on.
73     * @param object          $listener The listener object.
74     *
75     * @return void
76     */
77    public function addEventListener($events, $listener)
78    {
79        // Picks the hash code related to that listener
80        $hash = spl_object_hash($listener);
81
82        foreach ((array) $events as $event) {
83            // Overrides listener if a previous one was associated already
84            // Prevents duplicate listeners on same event (same instance only)
85            $this->_listeners[$event][$hash] = $listener;
86        }
87    }
88
89    /**
90     * Removes an event listener from the specified events.
91     *
92     * @param string|string[] $events
93     * @param object          $listener
94     *
95     * @return void
96     */
97    public function removeEventListener($events, $listener)
98    {
99        // Picks the hash code related to that listener
100        $hash = spl_object_hash($listener);
101
102        foreach ((array) $events as $event) {
103            unset($this->_listeners[$event][$hash]);
104        }
105    }
106
107    /**
108     * Adds an EventSubscriber. The subscriber is asked for all the events it is
109     * interested in and added as a listener for these events.
110     *
111     * @param EventSubscriber $subscriber The subscriber.
112     *
113     * @return void
114     */
115    public function addEventSubscriber(EventSubscriber $subscriber)
116    {
117        $this->addEventListener($subscriber->getSubscribedEvents(), $subscriber);
118    }
119
120    /**
121     * Removes an EventSubscriber. The subscriber is asked for all the events it is
122     * interested in and removed as a listener for these events.
123     *
124     * @param EventSubscriber $subscriber The subscriber.
125     *
126     * @return void
127     */
128    public function removeEventSubscriber(EventSubscriber $subscriber)
129    {
130        $this->removeEventListener($subscriber->getSubscribedEvents(), $subscriber);
131    }
132}
133