On Aug 22 2007 11:21, Bodo Eggert wrote: > >> >> But. The above regex does not seem to handle >> >> >> >> if ((a = b)); >> >> oops; >> >> >> >> I have tried to come up with a superduper regex that handles multiple >> >> (), but my regex fu seems to stop above two pairs of (). >> > >> >This is because you can't do that using finite regular expressions. >> > >> >Regular expressions are Type-3 grammars, but you'd need a Type-2 >> >grammar to express the Dyck language (and you need to parse a Dyck >> >Language, ignoring the non-dyck-parts). >> >> So what about this then... >> >> $s = shift @ARGV; >> $r = qr/a(??{ $r })?b/; > >This is not a regular expression, because it can't be parsed by a >finite state machine (DFA/NFA) without a stack. >http://en.wikipedia.org/wiki/Deterministic_finite_state_machine > >Obviously perl does allow non-regular expressions.
Exactly, and which is why my idea was to use a (??{ }) block to match if((())); but for some reason, it did not fly, and I do not know either why. Jan -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/