    public function handleText(&$token) {
        if (!$this->allowsElement('a')) return;

        if (strpos($token->data, '://') === false) {
            // our really quick heuristic failed, abort
            // this may not work so well if we want to match things like
            // "google.com", but then again, most people don't
            return;
        }

        // there is/are URL(s). Let's split the string:
        // Note: this regex is extremely permissive
        $bits = preg_split('#((?:https?|ftp)://[^\s\'"<>()]+)#S', $token->data, -1, PREG_SPLIT_DELIM_CAPTURE);

        $token = array();

        // $i = index
        // $c = count
        // $l = is link
        for ($i = 0, $c = count($bits), $l = false; $i < $c; $i++, $l = !$l) {
            if (!$l) {
                if ($bits[$i] === '') continue;
                $token[] = new HTMLPurifier_Token_Text($bits[$i]);
            } else {
                $token[] = new HTMLPurifier_Token_Start('a', array('href' => $bits[$i]));
                $token[] = new HTMLPurifier_Token_Text($bits[$i]);
                $token[] = new HTMLPurifier_Token_End('a');
            }
        }

    }
The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.