Riscrivere dinamicamente un url

[k.b]

$str = 'http://example.it/index.php?option=valore&view=idpagina&altravar=altrovalore';

$query_string = parse_url($str, PHP_URL_QUERY);
parse_str($query_string, $segments);

$url = 'http://example.com/'.implode('/', $segments);
echo $url;