File Toolkit/Core/EventDispatcher.php

1:	<?php declare(strict_types=1);
2:
3:	namespace Salient\Core;
4:
5:	use Psr\EventDispatcher\EventDispatcherInterface;
6:	use Psr\EventDispatcher\ListenerProviderInterface;
7:	use Psr\EventDispatcher\StoppableEventInterface;
8:	use Salient\Contract\Core\HasName;
9:	use Salient\Utility\Reflect;
10:	use Salient\Utility\Str;
11:	use LogicException;
12:
13:	/**
14:	* Dispatches events to listeners
15:	*
16:	* Implements PSR-14 (Event Dispatcher) interfaces.
17:	*
18:	* @api
19:	*/
20:	final class EventDispatcher implements EventDispatcherInterface, ListenerProviderInterface
21:	{
22:	/**
23:	* Listener ID => list of events
24:	*
25:	* @var array<int,string[]>
26:	*/
27:	private array $Listeners = [];
28:
29:	/**
30:	* Event => [ listener ID => listener ]
31:	*
32:	* @var array<string,array<int,callable>>
33:	*/
34:	private array $EventListeners = [];
35:
36:	private int $NextListenerId = 0;
37:	private ListenerProviderInterface $ListenerProvider;
38:
39:	/**
40:	* Creates a new EventDispatcher object
41:	*
42:	* If a listener provider is given, calls to methods other than
43:	* {@see EventDispatcher::dispatch()} will fail with a
44:	* {@see LogicException}.
45:	*/
46:	public function __construct(?ListenerProviderInterface $listenerProvider = null)
47:	{
48:	$this->ListenerProvider = $listenerProvider ?? $this;
49:	}
50:
51:	/**
52:	* Register an event listener with the dispatcher
53:	*
54:	* Returns a listener ID that can be passed to
55:	* {@see EventDispatcher::removeListener()}.
56:	*
57:	* @template TEvent of object
58:	*
59:	* @param callable(TEvent): mixed $listener
60:	* @param string[]\|string\|null $event An event or array of events. If
61:	* `null`, the listener is registered to receive events accepted by its
62:	* first parameter.
63:	*/
64:	public function listen(callable $listener, $event = null): int
65:	{
66:	$this->assertIsListenerProvider();
67:
68:	if ($event === null) {
69:	$event = [];
70:	foreach (Reflect::getAcceptedTypes($listener, true) as $name) {
71:	if (is_string($name)) {
72:	$event[] = $name;
73:	}
74:	}
75:	}
76:
77:	if ($event === []) {
78:	throw new LogicException('At least one event must be given');
79:	}
80:
81:	$id = $this->NextListenerId++;
82:	foreach ((array) $event as $event) {
83:	$event = Str::lower($event);
84:	$this->Listeners[$id][] = $event;
85:	$this->EventListeners[$event][$id] = $listener;
86:	}
87:
88:	return $id;
89:	}
90:
91:	/**
92:	* Dispatch an event to listeners registered to receive it
93:	*
94:	* @template TEvent of object
95:	*
96:	* @param TEvent $event
97:	* @return TEvent
98:	*/
99:	public function dispatch(object $event): object
100:	{
101:	$listeners = $this->ListenerProvider->getListenersForEvent($event);
102:
103:	foreach ($listeners as $listener) {
104:	if (
105:	$event instanceof StoppableEventInterface
106:	&& $event->isPropagationStopped()
107:	) {
108:	break;
109:	}
110:
111:	$listener($event);
112:	}
113:
114:	return $event;
115:	}
116:
117:	/**
118:	* @template TEvent of object
119:	*
120:	* @param TEvent $event
121:	* @return array<callable(TEvent): mixed>
122:	*/
123:	public function getListenersForEvent(object $event): array
124:	{
125:	$this->assertIsListenerProvider();
126:
127:	$events = array_merge(
128:	[get_class($event)],
129:	class_parents($event),
130:	class_implements($event),
131:	);
132:
133:	if ($event instanceof HasName) {
134:	$eventName = $event->getName();
135:	// If the event returns a name we already have, do nothing
136:	if (!is_a($event, $eventName)) {
137:	$events[] = $eventName;
138:	}
139:	}
140:
141:	$listenersByEvent = array_intersect_key(
142:	$this->EventListeners,
143:	array_change_key_case(array_fill_keys($events, null)),
144:	);
145:
146:	$listeners = [];
147:	foreach ($listenersByEvent as $eventListeners) {
148:	$listeners += $eventListeners;
149:	}
150:
151:	return array_values($listeners);
152:	}
153:
154:	/**
155:	* Remove an event listener from the dispatcher
156:	*
157:	* @param int $id A listener ID returned by
158:	* {@see EventDispatcher::listen()}.
159:	*/
160:	public function removeListener(int $id): void
161:	{
162:	$this->assertIsListenerProvider();
163:
164:	if (!array_key_exists($id, $this->Listeners)) {
165:	throw new LogicException('No listener with that ID');
166:	}
167:
168:	foreach ($this->Listeners[$id] as $event) {
169:	unset($this->EventListeners[$event][$id]);
170:	if (!$this->EventListeners[$event]) {
171:	unset($this->EventListeners[$event]);
172:	}
173:	}
174:
175:	unset($this->Listeners[$id]);
176:	}
177:
178:	private function assertIsListenerProvider(): void
179:	{
180:	if ($this->ListenerProvider !== $this) {
181:	throw new LogicException('Not a listener provider');
182:	}
183:	}
184:	}
185:

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