30      * @param string $eventName
35     function on($eventName, callable $callBack, $priority = 100) {  argument
37         if (!isset($this->listeners[$eventName])) {
38             $this->listeners[$eventName] = [
44             $this->listeners[$eventName][0] = false; // marked as unsorted
45             $this->listeners[$eventName][1][] = $priority;
46             $this->listeners[$eventName][2][] = $callBack;
54      * @param string $eventName
59     function once($eventName, callable $callBack, $priority = 100) {  argument
62         $wrapper = function() use ($eventName, $callBack, &$wrapper) {
64             $this->removeListener($eventName, $wrapper);
69         $this->on($eventName, $wrapper, $priority);
94      * @param string $eventName
99     function emit($eventName, array $arguments = [], callable $continueCallBack = null) {  argument
103             foreach ($this->listeners($eventName) as $listener) {
113             $listeners = $this->listeners($eventName);
142      * @param string $eventName
145     function listeners($eventName) {  argument
147         if (!isset($this->listeners[$eventName])) {
152         if (!$this->listeners[$eventName][0]) {
155 …   array_multisort($this->listeners[$eventName][1], SORT_NUMERIC, $this->listeners[$eventName][2]);
158             $this->listeners[$eventName][0] = true;
161         return $this->listeners[$eventName][2];
171      * @param string $eventName
175     function removeListener($eventName, callable $listener) {  argument
177         if (!isset($this->listeners[$eventName])) {
180         foreach ($this->listeners[$eventName][2] as $index => $check) {
182                 unset($this->listeners[$eventName][1][$index]);
183                 unset($this->listeners[$eventName][2][$index]);
198      * @param string $eventName
201     function removeAllListeners($eventName = null) {  argument
203         if (!is_null($eventName)) {
204             unset($this->listeners[$eventName]);