$re = '/^(.*?[._-]?)(?=[\W_])[._-]?(\()?([a-z]{2,3})(?(2)\)|)(?:[_\W]forced)?$/m';
$str = 'name.eng
name-eng
name(eng)
name(fri)_eng
name(fri)(eng)
name.eng.forced
name(eng).forced
name.(eng).forced
name.fri.eng.forced
name(fri).eng.forced
name.(fri).eng_forced
name-fri-eng.forced
name_(fri)_eng.forced
name(fri)_eng.forced
name(friday)_eng_forced
name(fri)(eng).forced
nameeng
nameeng.forced
name.eng).forced
name(fri)eng.forced
name(friday).engforced
name(fri)(eng)forced';
preg_match_all($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