public function validate($string, $config, $context) {
$length = strlen($string);
+ // empty hostname is OK; it's usually semantically equivalent:
+ // the default host as defined by a URI scheme is used:
+ //
+ // If the URI scheme defines a default for host, then that
+ // default applies when the host subcomponent is undefined
+ // or when the registered name is empty (zero length).
if ($string === '') return '';
if ($length > 1 && $string[0] === '[' && $string[$length-1] === ']') {
//IPv6