ControllerResolver.php

<?php

namespace Drupal\Core\Controller;

use Drupal\Core\Utility\CallableResolver;
use Symfony\Component\HttpFoundation\Request;

/**
 * ControllerResolver to enhance controllers beyond Symfony's basic handling.
 *
 * It adds one behavior:
 *
 *  - By default, a controller name follows the class::method notation. This
 *    class adds the possibility to use a service from the container as a
 *    controller by using a service:method notation (Symfony uses the same
 *    convention).
 */
class ControllerResolver implements ControllerResolverInterface {
    
    /**
     * Constructs a new ControllerResolver.
     *
     * @param \Drupal\Core\Utility\CallableResolver $callableResolver
     *   The callable resolver.
     */
    public function __construct(CallableResolver $callableResolver) {
    }
    
    /**
     * {@inheritdoc}
     */
    public function getControllerFromDefinition($controller, $path = '') {
        try {
            $callable = $this->callableResolver
                ->getCallableFromDefinition($controller);
        } catch (\InvalidArgumentException $e) {
            throw new \InvalidArgumentException(sprintf('The controller for URI "%s" is not callable.', $path), 0, $e);
        }
        return $callable;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getController(Request $request) : callable|false {
        if (!($controller = $request->attributes
            ->get('_controller'))) {
            return FALSE;
        }
        return $this->getControllerFromDefinition($controller, $request->getPathInfo());
    }

}