MobileRead Forums - View Single Post - Small suggestion for the search regex documentation

calmeilles · 11-25-2017, 08:07 AM

I was trying to search with the regex "[A-Z][A-Z][A-Z]" — looking for 3 consecutive capital letters but the search operated case-insensitive so I was getting results ABC, AbC, abc etc which came as a considerable surprise.

I believe that this is because my install has LOCALE=en_GB and the collate order for that is case insensitive. I may be wrong, but it's my best guess and actually doesn't matter.*

The Regex documentation page includes how to make a case sensitive [which is what we'd normally expect] ignore case with the "(?i)" syntax but not how to do the reverse. It actually turned out quite a chore tracking down what was required and a note in the documentation I feel would be useful.

What I ended up with was

Code:

(?-i:[A-Z]{3})

It's the possibility of -i that's missing and was quite obscure even in the Python docs.

(*I am curious if this is true or something else caused it.
If my guess is right then also mentioning that LOCALE can serious affect your regexes would also be useful.)

11-25-2017, 08:07 AM	#1
calmeilles Junior Member Posts: 5 Karma: 10 Join Date: Nov 2017 Device: Kindle	Small suggestion for the search regex documentation I was trying to search with the regex "[A-Z][A-Z][A-Z]" — looking for 3 consecutive capital letters but the search operated case-insensitive so I was getting results ABC, AbC, abc etc which came as a considerable surprise. I believe that this is because my install has LOCALE=en_GB and the collate order for that is case insensitive. I may be wrong, but it's my best guess and actually doesn't matter.* The Regex documentation page includes how to make a case sensitive [which is what we'd normally expect] ignore case with the "(?i)" syntax but not how to do the reverse. It actually turned out quite a chore tracking down what was required and a note in the documentation I feel would be useful. What I ended up with was Code: (?-i:[A-Z]{3}) It's the possibility of -i that's missing and was quite obscure even in the Python docs. (*I am curious if this is true or something else caused it. If my guess is right then also mentioning that LOCALE can serious affect your regexes would also be useful.)