Illuminate\Routing\UrlGenerator::addQueryString PHP Method

    protected function addQueryString($uri, array $parameters)
    {
        // If the URI has a fragment we will move it to the end of this URI since it will
        // need to come after any query string that may be added to the URL else it is
        // not going to be available. We will remove it then append it back on here.
        if (!is_null($fragment = parse_url($uri, PHP_URL_FRAGMENT))) {
            $uri = preg_replace('/#.*/', '', $uri);
        }
        $uri .= $this->getRouteQueryString($parameters);
        return is_null($fragment) ? $uri : $uri . "#{$fragment}";
    }