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<?php
declare(strict_types=1);
namespace Sabre\Event;
/**
* Wildcard Emitter Trait.
*
* This trait provides the implementation for WildCardEmitter
* Refer to that class for the full documentation about this
* trait.
*
* Normally you can just instantiate that class, but if you want to add
* emitter functionality to existing classes, using the trait might be a
* better way to do this.
*
* @copyright Copyright (C) fruux GmbH (https://fruux.com/)
* @author Evert Pot (http://evertpot.com/)
* @license http://sabre.io/license/ Modified BSD License
*/
trait WildcardEmitterTrait
{
/**
* Subscribe to an event.
*/
public function on(string $eventName, callable $callBack, int $priority = 100)
{
// If it ends with a wildcard, we use the wildcardListeners array
if ('*' === $eventName[\strlen($eventName) - 1]) {
$eventName = \substr($eventName, 0, -1);
$listeners = &$this->wildcardListeners;
} else {
$listeners = &$this->listeners;
}
// Always fully reset the listener index. This is fairly sane for most
// applications, because there's a clear "event registering" and "event
// emitting" phase, but can be slow if there's a lot adding and removing
// of listeners during emitting of events.
$this->listenerIndex = [];
if (!isset($listeners[$eventName])) {
$listeners[$eventName] = [];
}
$listeners[$eventName][] = [$priority, $callBack];
}
/**
* Subscribe to an event exactly once.
*/
public function once(string $eventName, callable $callBack, int $priority = 100)
{
$wrapper = null;
$wrapper = function () use ($eventName, $callBack, &$wrapper) {
$this->removeListener($eventName, $wrapper);
return \call_user_func_array($callBack, \func_get_args());
};
$this->on($eventName, $wrapper, $priority);
}
/**
* Emits an event.
*
* This method will return true if 0 or more listeners were successfully
* handled. false is returned if one of the events broke the event chain.
*
* If the continueCallBack is specified, this callback will be called every
* time before the next event handler is called.
*
* If the continueCallback returns false, event propagation stops. This
* allows you to use the eventEmitter as a means for listeners to implement
* functionality in your application, and break the event loop as soon as
* some condition is fulfilled.
*
* Note that returning false from an event subscriber breaks propagation
* and returns false, but if the continue-callback stops propagation, this
* is still considered a 'successful' operation and returns true.
*
* Lastly, if there are 5 event handlers for an event. The continueCallback
* will be called at most 4 times.
*/
public function emit(string $eventName, array $arguments = [], callable $continueCallBack = null): bool
{
if (\is_null($continueCallBack)) {
foreach ($this->listeners($eventName) as $listener) {
$result = \call_user_func_array($listener, $arguments);
if (false === $result) {
return false;
}
}
} else {
$listeners = $this->listeners($eventName);
$counter = \count($listeners);
foreach ($listeners as $listener) {
--$counter;
$result = \call_user_func_array($listener, $arguments);
if (false === $result) {
return false;
}
if ($counter > 0) {
if (!$continueCallBack()) {
break;
}
}
}
}
return true;
}
/**
* Returns the list of listeners for an event.
*
* The list is returned as an array, and the list of events are sorted by
* their priority.
*
* @return callable[]
*/
public function listeners(string $eventName): array
{
if (!\array_key_exists($eventName, $this->listenerIndex)) {
// Create a new index.
$listeners = [];
$listenersPriority = [];
if (isset($this->listeners[$eventName])) {
foreach ($this->listeners[$eventName] as $listener) {
$listenersPriority[] = $listener[0];
$listeners[] = $listener[1];
}
}
foreach ($this->wildcardListeners as $wcEvent => $wcListeners) {
// Wildcard match
if (\substr($eventName, 0, \strlen($wcEvent)) === $wcEvent) {
foreach ($wcListeners as $listener) {
$listenersPriority[] = $listener[0];
$listeners[] = $listener[1];
}
}
}
// Sorting by priority
\array_multisort($listenersPriority, SORT_NUMERIC, $listeners);
// Creating index
$this->listenerIndex[$eventName] = $listeners;
}
return $this->listenerIndex[$eventName];
}
/**
* Removes a specific listener from an event.
*
* If the listener could not be found, this method will return false. If it
* was removed it will return true.
*/
public function removeListener(string $eventName, callable $listener): bool
{
// If it ends with a wildcard, we use the wildcardListeners array
if ('*' === $eventName[\strlen($eventName) - 1]) {
$eventName = \substr($eventName, 0, -1);
$listeners = &$this->wildcardListeners;
} else {
$listeners = &$this->listeners;
}
if (!isset($listeners[$eventName])) {
return false;
}
foreach ($listeners[$eventName] as $index => $check) {
if ($check[1] === $listener) {
// Remove listener
unset($listeners[$eventName][$index]);
// Reset index
$this->listenerIndex = [];
return true;
}
}
return false;
}
/**
* Removes all listeners.
*
* If the eventName argument is specified, all listeners for that event are
* removed. If it is not specified, every listener for every event is
* removed.
*/
public function removeAllListeners(string $eventName = null)
{
if (\is_null($eventName)) {
$this->listeners = [];
$this->wildcardListeners = [];
} else {
if ('*' === $eventName[\strlen($eventName) - 1]) {
// Wildcard event
unset($this->wildcardListeners[\substr($eventName, 0, -1)]);
} else {
unset($this->listeners[$eventName]);
}
}
// Reset index
$this->listenerIndex = [];
}
/**
* The list of listeners.
*/
protected $listeners = [];
/**
* The list of "wildcard listeners".
*/
protected $wildcardListeners = [];
/**
* An index of listeners for a specific event name. This helps speeding
* up emitting events after all listeners have been set.
*
* If the list of listeners changes though, the index clears.
*/
protected $listenerIndex = [];
}
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