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<?php |
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/** |
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* @author Marwan Al-Soltany <[email protected]> |
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* @copyright Marwan Al-Soltany 2021 |
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* For the full copyright and license information, please view |
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* the LICENSE file that was distributed with this source code. |
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*/ |
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declare(strict_types=1); |
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namespace MAKS\Velox\Backend; |
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/** |
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* A class that offers simple events handling functionality (dispatching and listening). |
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* |
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* Example: |
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* ``` |
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* // listening on an event |
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* Event::listen('some.event', function ($arg1, $arg2) { |
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* // do some stuff ... |
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* }); |
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* |
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* // dispatching an event |
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* Event::dispatch('some.event', [$arg1, $arg2]); |
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* |
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* // check if an event has listeners |
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* Event::hasListener('some.event'); |
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* |
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* // check if an event is dispatched |
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* Event::isDispatch('some.event'); |
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* |
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* // get a registered or a new event object |
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* Event::get('some.event'); |
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* |
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* // get a all registered events |
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* Event::getRegisteredEvents(); |
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* ``` |
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* |
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* @package Velox\Backend |
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* @since 1.2.0 |
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* @api |
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*/ |
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class Event |
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{ |
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/** |
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* Here live all bindings. |
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*/ |
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protected static array $events = []; |
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/** |
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* Dispatches the passed event by executing all attached listeners and passes them the passed arguments. |
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* |
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* @param string $event Event name. |
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* @param array $arguments [optional] Arguments array. |
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* Note that the arguments will be spread (`...$args`) on the callback and an additional argument of the event name will be appended to the arguments. |
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* @param object|null $callbackThis [optional] The object the callback should be bound to. |
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* |
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* @return void |
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*/ |
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public static function dispatch(string $event, ?array $arguments = null, ?object $callbackThis = null): void |
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{ |
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if (static::hasListener($event) === false) { |
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static::get($event)->dispatched = true; |
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return; |
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} |
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$callbacks = &static::get($event)->listeners; |
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foreach ($callbacks as $callback) { |
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$parameters = array_merge(array_values($arguments ?? []), [$event]); |
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if ($callbackThis) { |
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$callback->call($callbackThis, ...$parameters); |
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continue; |
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} |
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$callback(...$parameters); |
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} |
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if (static::isDispatched($event) === false) { |
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static::get($event)->dispatched = true; |
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} |
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} |
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/** |
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* Listens on the passed event and attaches the passed callback to it. |
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* |
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* @param string $event Event name. |
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* @param callable $callback A callback to process the event. |
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* |
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* @return void |
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*/ |
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public static function listen(string $event, callable $callback): void |
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{ |
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static::get($event)->listeners[] = \Closure::fromCallable($callback); |
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} |
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/** |
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* Checks whether an event has already been dispatched or not. |
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* |
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* @param string $event Event name. |
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* |
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* @return bool |
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* |
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* @since 1.5.0 |
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*/ |
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public static function isDispatched(string $event): bool |
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{ |
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return static::get($event)->dispatched === true; |
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} |
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/** |
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* Checks whether an event has any listeners or not. |
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* |
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* @param string $event Event name. |
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* |
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* @return bool |
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* |
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* @since 1.5.0 |
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*/ |
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public static function hasListener(string $event): bool |
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{ |
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return empty(static::get($event)->listeners) === false; |
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} |
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/** |
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* Returns an event object by its name or creates it if it does not exist. |
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* The event object consists of the following properties: |
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* - `name`: The event name. |
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* - `dispatched`: A boolean flag indicating whether the event has been dispatched or not. |
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* - `listeners`: An array of callbacks. |
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* |
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* @param string $event Event name. |
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* |
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* @return object |
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* |
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* @since 1.5.0 |
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*/ |
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public static function get(string $event): object |
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{ |
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return static::$events[$event] ?? static::create($event); |
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} |
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/** |
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* Returns array of all registered events as an array `['event.name' => $eventObject, ...]`. |
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* |
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* @return object[] |
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*/ |
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public static function getRegisteredEvents(): array |
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{ |
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return static::$events; |
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} |
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/** |
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* Creates an event object and adds it to the registered events. |
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* |
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* @param string $event Event name. |
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* |
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* @return object |
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* |
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* @since 1.5.0 |
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*/ |
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protected static function create(string $event): object |
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{ |
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return static::$events[$event] = (object)[ |
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'name' => $event, |
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'dispatched' => false, |
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'listeners' => [], |
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]; |
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} |
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} |
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