class RouteProcessorManager

class RouteProcessorManager implements OutboundRouteProcessorInterface {
    
    /**
     * Holds the array of outbound processors to cycle through.
     *
     * @var array
     *   An array whose keys are priorities and whose values are arrays of path
     *   processor objects.
     */
    protected $outboundProcessors = [];
    
    /**
     * Holds the array of outbound processors, sorted by priority.
     *
     * @var array
     *   An array of path processor objects.
     */
    protected $sortedOutbound = [];
    
    /**
     * Adds an outbound processor object to the $outboundProcessors property.
     *
     * @param \Drupal\Core\RouteProcessor\OutboundRouteProcessorInterface $processor
     *   The processor object to add.
     * @param int $priority
     *   The priority of the processor being added.
     */
    public function addOutbound(OutboundRouteProcessorInterface $processor, $priority = 0) {
        $this->outboundProcessors[$priority][] = $processor;
        $this->sortedOutbound = [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function processOutbound($route_name, Route $route, array &$parameters, BubbleableMetadata $bubbleable_metadata = NULL) {
        $processors = $this->getOutbound();
        foreach ($processors as $processor) {
            $processor->processOutbound($route_name, $route, $parameters, $bubbleable_metadata);
        }
    }
    
    /**
     * Returns the sorted array of outbound processors.
     *
     * @return array
     *   An array of processor objects.
     */
    protected function getOutbound() {
        if (empty($this->sortedOutbound)) {
            $this->sortedOutbound = $this->sortProcessors();
        }
        return $this->sortedOutbound;
    }
    
    /**
     * Sorts the processors according to priority.
     */
    protected function sortProcessors() {
        $sorted = [];
        krsort($this->outboundProcessors);
        foreach ($this->outboundProcessors as $processors) {
            $sorted = array_merge($sorted, $processors);
        }
        return $sorted;
    }

}