Re^2: Zero-width look-ahead regexp question

Replies are listed 'Best First'.
Re^3: Zero-width look-ahead regexp question by rovf (Priest) on Jul 01, 2008 at 12:10 UTC
The word boundary does not help, because for instance `'FOOBAR X'` and `'FOOBARX'` are both strings which should be accepted (because both `BAR X` and `BARX` are considered different from <BAR>), while `'FOOBAR'` should be rejected. Actually I meanwhile believe to having found a solution to my problem while having lunch (it is surprising how a glass of Italian Chardonnay can do good to the brain cells): `$name =~ /^FOO(?!(BAR\|BAZ)$)/` [download] so unless someone can find a flaw with this (the examples where I tried it, worked so far), I think I will stick with it. It is not a beautiful solution, though, because if I would like one day to pick up what is to the right of FOO, I can't do it. So I'm still interested in hearing alternative proposals. Maybe just to make it clear, here are concrete examples: The following strings should be accepted: `FOOABC FOO_BAR FOOBA FOOBAZZZZ FOOBAR BAZ` [download] while the following should be rejected: `FOOBAR FOOBAZ BARBAZ` [download] -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l] [select]
Re^4: Zero-width look-ahead regexp question by ww (Archbishop) on Jul 02, 2008 at 03:25 UTC
"it is surprising how a glass of Italian Chardonnay can do good to the brain cells" But it is far from surprising that providing a clear specification of what you seek will enhance the liklihood that the Monks will provide useful advice. I mention this because your original post. The first bit of code, `[/^(BAR\|BAZ)$/`, requires that `/BA[RZ]/` NOT be the last element of your string, while the second, the negative lookahead, `(?!(BAR\|BAZ)).$/`, allows anything NOT `/BA[RZ]/` followed by (your dot_deathstar, `.` any number of any characters INCLUDING `/BA[RZ]/`. Judging by other replies, I wasn't the only one confounded thereby. yet very shortly after your clarifying example (in this node's parent) you got a reasonably general answer from Anonymonk (and re that answer, I'm not sure I buy the advice to "avoid as the plague the use of capturing groups in the decomposed regexes..." but the thought process outlined in that node deserves a ++ ((and got same from me)).	[reply] [d/l] [select]
Re^5: Zero-width look-ahead regexp question by rovf (Priest) on Jul 02, 2008 at 07:02 UTC
while the second `[...]` allows anything NOT /BARZ/ followed by (your dot_deathstar, . any number of any characters INCLUDING /BARZ/* That's why I had added but of course this is not quite right, since it would also reject FOOBARX, but you are right that I should have been much more clear in my OP. I had included the (wrong) approach so that you don't believe I would just ask for help without at least trying to solve it on my own, but in the way I did it, it just caused a lot of confusion.... -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l]