Regex negation in vim

Question

In vim I would like to use regex to highlight each line that ends with a letter, that is preceeded by neither // nor :. I tried the following

syn match systemverilogNoSemi "\(.*\(//\|:\).*\)\@!\&.*[a-zA-Z0-9_]$" oneline

This worked very good on comments, but did not work on lines containing colon. Any idea why?

Answer 1

Because with this regex vim can choose any point for starting match for your regular expression. Obviously it chooses the point where first concat matches (i.e. does not have // or :). These things are normally done by using either

\v^%(%(\/\/|\:)@!.)*\w$

(removed first concat and the branch itself, changed .* to %(%(\/\/|\:)@!.)*; replaced collection with equivalent \w; added anchor pointing to the start of line): if you need to match the whole line. Or negative look-behind if you need to match only the last character. You can also just add anchor to the first concat of your variant (you should remove trailing .* from the first concat as it is useless, and the branch symbol for the same reason).

Note: I have no idea why your regex worked for comments. It does not work with comments the way you need it in all cases I checked.

Answer 2

does this work for you?

^\(\(//\|:\)\@<!.\)*[a-zA-Z0-9_]$