public function buildValidator()
    {
        if ($this->validator_built) {
            return $this->validator;
        }

        foreach ($this->rows as $name => $row) {
            foreach ($row->getRules() as $rule) {
                $this->validator->addRule($name, $rule);
            }
            $row->disableRules();
        }
        $this->validator_built = true;

        return $this->validator;
    }