gnu-social/src/Core/Event.php

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<?php
declare(strict_types = 1);
// {{{ License
// This file is part of GNU social - https://www.gnu.org/software/social
//
// GNU social is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// GNU social is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with GNU social. If not, see <http://www.gnu.org/licenses/>.
// }}}
/**
* GNU social's event handler wrapper around Symfony's,
* keeping our old interface, which is more convenient and just as powerful
*
* @package GNUsocial
* @category Event
*
* @author Hugo Sales <hugo@hsal.es>
* @copyright 2020-2021 Free Software Foundation, Inc http://www.fsf.org
* @license https://www.gnu.org/licenses/agpl.html GNU AGPL v3 or later
*/
namespace App\Core;
use ReflectionFunction;
use Symfony\Component\EventDispatcher\EventDispatcherInterface;
use Symfony\Component\EventDispatcher\GenericEvent;
abstract class Event
{
/**
* Constants to be returned from event handlers, for increased clarity
*
* bool stop - Stop other handlers from processing the event
* bool next - Allow the other handlers to process the event
*/
public const stop = false;
public const next = true;
private static EventDispatcherInterface $dispatcher;
public static function setDispatcher(EventDispatcherInterface $dis): void
{
self::$dispatcher = $dis;
}
/**
* Add an event handler
*
* To run some code at a particular point in GNU social processing.
* Named events include receiving an XMPP message, adding a new notice,
* or showing part of an HTML page.
*
* The arguments to the handler vary by the event. Handlers can return
* two possible values: false means that the event has been replaced by
* the handler completely, and no default processing should be done.
* Non-false means successful handling, and that the default processing
* should succeed. (Note that this only makes sense for some events.)
*
* Handlers can also abort processing by throwing an exception; these will
* be caught by the closest code and displayed as errors.
*
* @param string $name Name of the event
* @param callable $handler Code to run
* @param int $priority Higher runs first
*/
public static function addHandler(
string $name,
callable $handler,
int $priority = 0,
string $ns = 'GNUsocial.',
): void {
self::$dispatcher->addListener(
$ns . $name,
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function ($event, $event_name, $dispatcher) use ($handler, $name) {
// Old style of events (preferred)
if ($event instanceof GenericEvent) {
if ($handler(...$event->getArguments()) === self::stop) {
$event->stopPropagation();
}
return $event;
}
// @codeCoverageIgnoreStart
// Symfony style of events
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Log::warning("Event::addHandler for {$name} doesn't Conform to GNU social guidelines. Use of this style of event is discouraged.");
$handler($event, $event_name, $dispatcher);
// @codeCoverageIgnoreEnd
},
$priority,
);
}
/**
* Handle an event
*
* Events are any point in the code that we want to expose for admins
* or third-party developers to use.
*
* We pass in an array of arguments (including references, for stuff
* that can be changed), and each assigned handler gets run with those
* arguments. Exceptions can be thrown to indicate an error.
*
* @param string $name Name of the event that's happening
* @param array $args Arguments for handlers
* @param string $ns Namspace for the event
*
* @return bool flag saying whether to continue processing, based
* on results of handlers
*/
public static function handle(string $name, array $args = [], string $ns = 'GNUsocial.'): bool
{
return !(self::$dispatcher->dispatch(new GenericEvent($name, $args), $ns . $name)->isPropagationStopped());
}
/**
* Check to see if an event handler exists
*
* Look to see if there's any handler for a given event, or narrow
* by providing the name of a specific plugin class.
*
* @param string $name Name of the event to look for
* @param string $plugin Optional name of the plugin class to look for
*
* @return bool flag saying whether such a handler exists
*/
public static function hasHandler(string $name, ?string $plugin = null, string $ns = 'GNUsocial.'): bool
{
$listeners = self::$dispatcher->getListeners($ns . $name);
if (isset($plugin)) {
foreach ($listeners as $event_handler) {
$class = (new ReflectionFunction((new ReflectionFunction($event_handler))->getStaticVariables()['handler']))->getClosureScopeClass()->getName();
if ($class === $plugin) {
return true;
}
}
} else {
return !empty($listeners);
}
return false;
}
/**
* Get the array of handlers for $name
*
* @param string $name Name of event
*/
public static function getHandlers(string $name, string $ns = 'GNUsocial.'): array
{
return self::$dispatcher->getListeners($ns . $name);
}
}