protected function currentUrl()
    {
        if (isset(static::$static[__FUNCTION__])) {
            return static::$static[__FUNCTION__];
        }
        $url = $this->currentUrlScheme().'://';
        $url .= $this->currentUrlHost();
        $url .= $this->currentUrlUri();

        return static::$static[__FUNCTION__] = $url;
    }