reduce usage of perl = TRUE in regex, where possible

[strengejacke]

Currently, we use perl = TRUE in several instances where we have regular expression. However, this is very slow. If possible, we should remove it. Can anyone help judging the patterns and see if perl = TRUE is really needed?

https://github.com/easystats/insight/search?q=%22perl+%3D+TRUE%22

@IndrajeetPatil @bwiernik @vincentarelbundock

[vincentarelbundock]

Are any of these calls executed thousands of times? Otherwise, even if a micro benchmark shows that perl regexes are an order of magnitude slower, noone will ever notice.

I'm super into performance improvement and think there are probably lots of low-hanging fruits in easystats, but it's usually best to start with profiling to avoid premature optimization, and loss of functionality.

[strengejacke]

Yeah, probably you're right. I think the find_*() functions are called multiple times. And I have already replaced a lot of instances, e.g. also using startsWith() / endsWith() or adding fixed = TRUE. Maybe in total, this might give a noticeable difference?

[strengejacke]

In general, I'm curious if patterns like this one "^(?!sd_|cor_)(.*)" works w/o perl = TRUE?

[vincentarelbundock]

In general, I'm curious if patterns like this one "^(?!sd_|cor_)(.*)" works w/o perl = TRUE?

Ya, I'm pretty sure that look-ahead and look-behinds do not work with the base R regexes, so we need perl=TRUE in those cases.

[strengejacke]

Ok. But maybe here:

.grep_non_smoothers <- function(x) {
  grepl("^(?!(s\\())", x, perl = TRUE) &
    # this one captures smoothers in zi- or mv-models from gam
    grepl("^(?!(s\\.\\d\\())", x, perl = TRUE) &
    grepl("^(?!(ti\\())", x, perl = TRUE) &
    grepl("^(?!(te\\())", x, perl = TRUE) &
    grepl("^(?!(t2\\())", x, perl = TRUE) &
    grepl("^(?!(gam::s\\())", x, perl = TRUE) &
    grepl("^(?!(gam::s\\.\\d\\())", x, perl = TRUE) &
    grepl("^(?!(VGAM::s\\())", x, perl = TRUE) &
    grepl("^(?!(mgcv::s\\())", x, perl = TRUE) &
    grepl("^(?!(mgcv::s\\.\\d\\())", x, perl = TRUE) &
    grepl("^(?!(mgcv::ti\\())", x, perl = TRUE) &
    grepl("^(?!(mgcv::te\\())", x, perl = TRUE) &
    grepl("^(?!(brms::s\\())", x, perl = TRUE) &
    grepl("^(?!(brms::t2\\())", x, perl = TRUE) &
    grepl("^(?!(smooth_sd\\[))", x, perl = TRUE)
}

we could instead use !startsWith()? (at least for some of those expressions)