$re = '/(?<LanguageTag>(?<langtag>(?<language>(?:[a-z]{2,3}(?<extlang>(?:\-[a-z]{3}){0,3}))|[a-z]{4}|(?<subtag>[a-z]{5,8}))(?:\-(?<script>[a-z]{4}))?(?:\-(?<region>[a-z]{2}|[0-9]{3}))?(?:\-(?<variant>[0-9a-z]{5,8}|[0-9][0-9a-z]{3}))*(?:\-(?<extension>(?<singleton>[a-wy-z0-9])(?:\-[0-9a-z]{2,8})+))*)|(?<privateuse>[xX](?:\-[0-9a-z]{1,8})+)|(?<grandfathered>[a-z]{1,3}(?:\-[0-9a-z]{2,8}){1,2}))/mi';
$str = '';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php