CODEWITHSUNDEEP
regexpcre
3000
3000

Reputation: 187

Improve regex that works

I'm not a regex expert, so please be nice :-)

I created this regex to verify if a user submitted a day of the week (in italian language):

/((lun|mart|giov)e|mercol(e?)|vener)d(ì|i('?)|í)|sabato|domenica/

This regex perfectly works and it matches the following:

Now consider the first part of the regex and focus on venerdì: as you can see, I added an OR (|) just to manage the venerdì day, just because of the presence of that “r”.

Anything works just fine but I’m here to ask if is there any way to start the regex this way:

(lun|mar|giov|ven)e

and then manage that “r” some way.

I red about backrefences and conditionals but I’m not sure they can be of any help.

My idea is something like: “if the first group captured ‘ven’, than add “r” to the “e” right after the end of the group.

Is this possible?

Upvotes: 1

Views: 53

Answers (1)

tobias_k
tobias_k

Reputation: 82949

Don't "golf" your regex. If you want to improve it at all, make it more readable. While it it certainly worthwile to use different cases for the different "i" variants, everything else should IMHO be kept as simple as possible.

How about something like this?

(lune|marte|mercole?|giove|vener)d(ì|i'?|í)|sabato|domenica

Don't use backreferences and other advanced features if you don't need them, just to make your regex a few chars shorter. Even if you would still understand what it means, think about your fellow co-developers -- or just yourself two months from now.

I just removed a few redundant (...) and the "shared e" part. Note how (besides the (...)) it is the same length, whether you use (lun|mart|giov)e or lune|marte|giove, but the latter is arguably more readable. Similarly, a backreference or some conditional would likely make your regex longer instead of shorter -- and considerably more complicated.

Upvotes: 2

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