private function getIndexForObject($object)
    {
        $reflClass = new ReflectionClass($object);

        $annotation = $this->reader->getClassAnnotation($reflClass, '\Keratine\Lucene\Mapping\Annotation\Indexable');

        if (!$annotation) {
            // throw new \Exception(sprintf('%s must define annotation @%s', get_class($object), '\Keratine\Lucene\Mapping\Annotation\Indexable'));
            return;
        }

        if (empty($annotation->index)) {
            AnnotationException::requiredError('index', '\Keratine\Lucene\Mapping\Annotation\Indexable', $object, 'string');
        }

        if(false === isset($this->indices[$annotation->index])) {
            throw new \Exception(sprintf('Unknown index "%s".', $annotation->index));
        }

        if (false === $this->indices[$annotation->index] instanceof SearchIndexInterface) {
            throw new \Exception(
                sprintf('Index "%s" must be an instance of "ZendSearch\Lucene\SearchIndexInterface". "%s" given.',
                    $annotation->index,
                    is_object($this->indices[$annotation->index]) ? get_class($this->indices[$annotation->index]) : $this->indices[$annotation->index]
                )
            );
        }

        return $this->indices[$annotation->index];
    }