PHP make it link class

makeItLink.php

class MakeItLink {
    protected function _link_www( $matches ) {
        $url = $matches[2];
        $url = MakeItLink::cleanURL( $url );
        if( empty( $url ) ) {
            return $matches[0];
        }

        return "{$matches[1]}<a href='{$url}'>{$url}</a>";
    }

    public function cleanURL( $url ) {
        if( $url == '' ) {
            return $url;
        }

        $url = preg_replace( "|[^a-z0-9-~+_.?#=!&;,/:%@$*'()x80-xff]|i", '', $url );
        $url = str_replace( array( "%0d", "%0a" ), '', $url );
        $url = str_replace( ";//", "://", $url );

        /* If the URL doesn't appear to contain a scheme, we
         * presume it needs http:// appended (unless a relative
         * link starting with / or a php file).
         */
        if(
            strpos( $url, ":" ) === false
            && substr( $url, 0, 1 ) != "/"
            && !preg_match( "|^[a-z0-9-]+?.php|i", $url )
        ) {
            $url = "http://{$url}";
        }

        // Replace ampersans and single quotes
        $url = preg_replace( "|&([^#])(?![a-z]{2,8};)|", "&#038;$1", $url );
        $url = str_replace( "'", "&#039;", $url );

        return $url;
    }

    public function transform( $text ) {
        $text = " {$text}";

        $text = preg_replace_callback(
            '#(?<=[\s>])(\()?([\w]+?://(?:[\w\\x80-\\xff\#$%&~/\-=?@\[\](+]|[.,;:](?![\s<])|(?(1)\)(?![\s<])|\)))*)#is',
            array( 'MakeItLink', '_link_www' ),
            $text
        );

        $text = preg_replace( '#(<a( [^>]+?>|>))<a [^>]+?>([^>]+?)</a></a>#i', "$1$3</a>", $text );
        $text = trim( $text );

        return $text;
    }
}