protected function getDefaultSchemaGrammar()
    {
        $driver = $this->ci->db->dbdriver;
        switch ($driver) {
            case 'mysql':
            case 'mysqli':
                return $this->withTablePrefix(new \Illuminate\Database\Schema\Grammars\MySqlGrammar);
        }

        throw new \InvalidArgumentException("Unsupported CodeIgniter database driver '$driver'");
    }