Updated the code style of Service/XDatabase/Core/Database.php
    protected function getDriver() {
        if ( null === $this->driver ) {
            $this->driver = $this->getDriverByConfig();
        }
        return $this->driver;
    }
    From:
    protected function getDriver() {
        return $this->driver = ( is_null($this->driver) )
        ? $this->getDriverByConfig()
        : $this->driver;
    }