public static function autodiscover_feed_url($url){
            $rss =  new moodle_simplepie();
            $rss->set_feed_url($url);
            $rss->set_autodiscovery_level(SIMPLEPIE_LOCATOR_ALL);
            // When autodiscovering an RSS feed, simplepie will try lots of
            // rss links on a page, so set the timeout high
            $rss->set_timeout(20);
            $rss->init();

            if($rss->error()){
                return $url;
            }

            // return URL without quoting..
            $discoveredurl = new moodle_url($rss->subscribe_url());
            return $discoveredurl->out(false);
    }
public static function autodiscover_feed_url($url){
            $rss =  new moodle_simplepie();
            $rss->set_feed_url($url);
            $rss->set_autodiscovery_level(SIMPLEPIE_LOCATOR_ALL);
            // When autodiscovering an RSS feed, simplepie will try lots of
            // rss links on a page, so set the timeout high
            $rss->set_timeout(20);
            $rss->init();

            if($rss->error()){
                return $url;
            }

            // return URL without quoting..
            $discoveredurl = new moodle_url($rss->subscribe_url());
            return $discoveredurl->out(false);
    }
public static function autodiscover_feed_url ( $ url ) { $ rss = new moodle_simplepie ( ) ; $ rss -> set_feed_url ( $ url ) ; $ rss -> set_autodiscovery_level ( SIMPLEPIE_LOCATOR_ALL ) ; // When autodiscovering an RSS feed, simplepie will try lots of // rss links on a page, so set the timeout high $ rss -> set_timeout ( 20 ) ; $ rss -> init ( ) ; if ( $ rss -> error ( ) ) { return $ url ; } // return URL without quoting.. $ discoveredurl = new moodle_url ( $ rss -> subscribe_url ( ) ) ; return $ discoveredurl -> out ( false ) ; }
Autodiscovers a feed url from a given url, to be used by the formslibs
filter function

Uses simplepie with autodiscovery set to maximum level to try and find
a feed to subscribe to.
See: http://simplepie.org/wiki/reference/simplepie/set_autodiscovery_level

@param string URL to autodiscover a url
@return string URL of feed or original url if none found
Autodiscovers a feed url from a given url to be used by the formslibs filter function