auto-alt-text / src / App / Events / SimpleEventDispatcher.php

SimpleEventDispatcher.php in Auto Alt Text 2.7.0, at src/App/Events/SimpleEventDispatcher.php

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1	<?php
2
3	namespace AATXT\App\Events;
4
5	/**
6	* Simple implementation of the EventDispatcher interface.
7	*
8	* This dispatcher maintains an array of listeners indexed by event class
9	* and calls them in order when events are dispatched.
10	*
11	* Example usage:
12	* ```php
13	* $dispatcher = new SimpleEventDispatcher();
14	*
15	* // Register a listener
16	* $dispatcher->listen(UserCreatedEvent::class, function($event) {
17	* echo "User {$event->getUserId()} was created";
18	* });
19	*
20	* // Dispatch an event
21	* $dispatcher->dispatch(new UserCreatedEvent($userId));
22	* ```
23	*
24	* @package AATXT\App\Events
25	*/
26	final class SimpleEventDispatcher implements EventDispatcherInterface
27	{
28	/**
29	* Registered listeners indexed by event class.
30	*
31	* @var array<string, array<callable>>
32	*/
33	private $listeners = [];
34
35	/**
36	* Dispatch an event to all registered listeners.
37	*
38	* Listeners are called in the order they were registered.
39	* Each listener receives the event object as its argument.
40	*
41	* @param object $event The event to dispatch
42	* @return object The dispatched event (may be modified by listeners)
43	*/
44	public function dispatch(object $event): object
45	{
46	$eventClass = get_class($event);
47
48	// Call listeners registered for the exact class
49	if (isset($this->listeners[$eventClass])) {
50	foreach ($this->listeners[$eventClass] as $listener) {
51	$listener($event);
52	}
53	}
54
55	// Also call listeners registered for parent classes/interfaces
56	foreach ($this->listeners as $registeredClass => $listeners) {
57	if ($registeredClass !== $eventClass && $event instanceof $registeredClass) {
58	foreach ($listeners as $listener) {
59	$listener($event);
60	}
61	}
62	}
63
64	return $event;
65	}
66
67	/**
68	* Register a listener for a specific event class.
69	*
70	* @param string $eventClass The event class to listen for
71	* @param callable $listener The listener callback
72	* @return void
73	*/
74	public function listen(string $eventClass, callable $listener): void
75	{
76	if (!isset($this->listeners[$eventClass])) {
77	$this->listeners[$eventClass] = [];
78	}
79
80	$this->listeners[$eventClass][] = $listener;
81	}
82
83	/**
84	* Remove a listener for a specific event class.
85	*
86	* Note: This only works for listeners that can be compared with ===.
87	* Anonymous functions are only equal if they are the same instance.
88	*
89	* @param string $eventClass The event class
90	* @param callable $listener The listener to remove
91	* @return bool True if the listener was found and removed
92	*/
93	public function removeListener(string $eventClass, callable $listener): bool
94	{
95	if (!isset($this->listeners[$eventClass])) {
96	return false;
97	}
98
99	$key = array_search($listener, $this->listeners[$eventClass], true);
100
101	if ($key === false) {
102	return false;
103	}
104
105	unset($this->listeners[$eventClass][$key]);
106	$this->listeners[$eventClass] = array_values($this->listeners[$eventClass]);
107
108	return true;
109	}
110
111	/**
112	* Get all listeners for a specific event class.
113	*
114	* @param string $eventClass The event class
115	* @return array<callable> Array of registered listeners
116	*/
117	public function getListeners(string $eventClass): array
118	{
119	return $this->listeners[$eventClass] ?? [];
120	}
121
122	/**
123	* Check if there are any listeners for a specific event class.
124	*
125	* @param string $eventClass The event class
126	* @return bool True if there are registered listeners
127	*/
128	public function hasListeners(string $eventClass): bool
129	{
130	return !empty($this->listeners[$eventClass]);
131	}
132
133	/**
134	* Remove all listeners for a specific event class.
135	*
136	* @param string $eventClass The event class
137	* @return int The number of listeners removed
138	*/
139	public function clearListeners(string $eventClass): int
140	{
141	if (!isset($this->listeners[$eventClass])) {
142	return 0;
143	}
144
145	$count = count($this->listeners[$eventClass]);
146	unset($this->listeners[$eventClass]);
147
148	return $count;
149	}
150
151	/**
152	* Remove all listeners for all event classes.
153	*
154	* @return void
155	*/
156	public function clearAllListeners(): void
157	{
158	$this->listeners = [];
159	}
160
161	/**
162	* Get the count of listeners for a specific event class.
163	*
164	* @param string $eventClass The event class
165	* @return int Number of registered listeners
166	*/
167	public function getListenerCount(string $eventClass): int
168	{
169	return count($this->listeners[$eventClass] ?? []);
170	}
171	}
172