public static function url($url){

		$url = static::_nullValue($url);
		if(!$url){

			return $url;
		}

		$query = parse_url($url, PHP_URL_QUERY);
		if(!$query){

			return $url;
		}

		parse_str($query, $query_parts);

		// First urldecode to be sure that we do not re-encode the query parts.
		$query_parts = array_map('static::_nested_urldecode', $query_parts);

		// http_build_query will take care of the urlencode.
		return strtok($url, '?') . '?' . http_build_query($query_parts);
	}