Apple's regular expression parser is based on the ICU parser. It uses flags to control alphabetic case in the match sequence.

If you're using the Regular Expression statement you can force the entire expression to be case insensitive as an option in the statement itself.

If you're using a regexp anywhere else in Yate you can use the flags: (?i) to enable case insensitivity and (?-i) to disable it. You can get at the flags from an action field's context menu.

As far as I know, there is no way to force case transformations via the replace template. You have to do it post extraction. You can extract ranges of everything matched and build up a new result doing case transformations on a range of the result. It's not pretty. 🙁

BTW: As ICU does not use \L, Yate repurposes it to mean ignore regexp sequences in everything that follows.

This one annoyed me as it seems as if is a useful feature. I've investigated and found that I can extend the Apple regexp functionality and implement it with a slightly different syntax.

I can allow case transformations in the replace template within a capture group. $L1 would mean insert capture group 1 all in lower case. $U3 would mean insert capture group 3 all in upper case. $2 would be a typical insert capture group 2 without any case conversion.

Would this work for you?

Thanks for letting me know. It will also work with named capture groups. $L(?<name> ...)

It'll be in v8.2.3

Released in v8.2.3 today