+$url = parse_url($src_url);
+if (FALSE === $url || empty($url["host"]))
+ die("Invalid url\n");
+
+$stylesheets = array(
+ "twitter.com" => "twitter_user_timeline2rss.xsl",
+);
+
+if (FALSE === array_key_exists($url["host"], $stylesheets))
+ die("Unsupported host\n");
+
+$stylesheet = $stylesheets[$url["host"]];