$braces = qr/(?<braces>\{ ([^\{\}]++ | (?&braces))*+ \} )/x;
if ($h =~ s/class \s+ (?<class_name> \w+) \s* (\: (\s* \w*)? \s* (?<ancestor> \w+))? \s* $braces//x) {
   print "hi\n";
}