/**
  * @param OperatorInterface $operator
  * @return HandlerInterface
  * @throws \ABK\QueryBundle\Filter\Exceptions\InvalidArgumentException
  */
 public function getHandler(OperatorInterface $operator)
 {
     $name = $operator->getName();
     $type = $operator->getType();
     if (!isset($this->registeredHandlers[$type]) || !in_array($name, $this->registeredHandlers[$type])) {
         throw new InvalidArgumentException('The given operator "' . $name . '" does not have an implemented handler for type ' . $type . '.');
     }
     if ($operator instanceof ComparisonOperatorInterface) {
         return $this->getComparisonOperatorHandlerInstance($operator);
     }
     return null;
 }