PHP Closure Event Dispatcher

Event.php

<?php

class Event {
    private $events = [];
    
    public function on($event, $callback, $priority = 0) {
        // check if an event is not already created
        if (!isset($this->events[$event])) $this->events[$event] = new \SplPriorityQueue();
        // make $this available in closures
        if (is_object($callback) && $callback instanceof \Closure) {
            $callback = $callback->bindTo($this, $this);
        }
        // add the event to the priority queue
        $this->events[$event]->insert($callback, $priority);
    }
    
    public function trigger($event, $params=[]){
        if (!isset($this->events[$event])){
            return $this;
        }
        
        $queue = $this->events[$event];
        $queue->top();
        
        // process the queue
        while($queue->valid()){
            $action = $queue->current();
            if (is_callable($action)){
                if (call_user_func_array($action, $params) === false) {
                    break; // stop propagation on error
                }
            }
            $queue->next();
        }
        
        return $this;
    }
}