Hi Josiah, Why not share a reprex / something we can copy and paste to directly reproduce the issue?
In any case, I suspect this depends on the underlying PCRE implementation, and so isn't really directly an R issue. You might have luck if you rewrite your regular expression from: (?<=(FeatureServer|MapServer)/)[0-9]+/?$ to something like (I didn't count parentheses below so assume I made a mistake) (?:(?<=FeatureServer)|(?<=MapServer)))/)[0-9]+/?$ Or, alternatively -- does this really need to be a lookbehind? Can you just match that text as-is and then capture whatever you happen to find in front of it? Best, Kevin On Tue, May 27, 2025 at 3:07 PM Josiah Parry <josiah.pa...@gmail.com> wrote: > > Hi all, > > I've encountered an issue where using `perl = TRUE` for regular expressions > with grepl() causes an error on ubuntu CI runners only. > > Is this a known limitation of perl = TRUE for grep and family in base R? Or > is there a suggested workaround? > > The issue is specifically with lookbehinds: > > PCRE pattern compilation error > 'lookbehind assertion is not fixed length' > at '(?<=(FeatureServer|MapServer)/)[0-9]+/?$' > > Any guidance would be very much appreciated! I'd like to avoid adding a > stringi dependency if possible. > > [[alternative HTML version deleted]] > > ______________________________________________ > R-package-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-package-devel ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel