using regex to split and replace text in a string

[jollyrancher12]

rust-pcre2/src/bytes.rs

Line 400 in 2f87eb9

/// Once compiled, it can be used repeatedly to search, split or replace

how can this regex be used to split / replace text in a string? i tried using the split function but is erroring with the message "required for Regex to implement Pattern<'_>". Not sure if I am misunderstanding how to use the regex to split strings or if this is a bug?

[BurntSushi]

The bug here is the docs. I likely copied them from elsewhere. I just never got around to actually implementing the split or replace routines. You can either implement them for your specific use case, or you or someone could submit a PR adding them to the API of this crate. (And if you do that, I'd suggest copying what is in the regex crate.)

In general this crate exposes PCRE2 stuff for my own purposes in ripgrep. If folks want additional stuff I'll do my best to merge patches. But I do not have time to do it myself.

[BurntSushi]

Also, I would strongly urge you to use the regex crate if you can. I realize PCRE2 has a bunch of fancy features, but if you're processing untrusted input from somewhere, it's very easily to fall victim to ReDoS.

If you do want to use the regex crate but don't know how to avoid using look-around or similar fancy features, I can try to help if you want to post a question to the regex repo: https://github.com/rust-lang/regex/discussions --- If you do, just please try to include a full minimal example of what you're trying to do: your inputs, what you've tried, the output you get and the output you want.

[jollyrancher12]

ah i see, yes unfortunately look arounds are necessary for our use case and are already pretty deeply embedded into our work flow.
if i can't get around the look-arounds, would you recommend using the fancy-regex crate over this pcre2 crate? i saw that fancy-regex was built on top of your rust regex crate and implements look arounds but did not see much info about its performance. (and thank you so much for your quick reply!!)

[BurntSushi]

I don't have much direct experience with fancy-regex to be honest. It isn't as mature as PCRE2, but if it works for your use case, it's worth a try. It won't save you from ReDoS though. ReDoS is a fundamental problem in pretty much any regex where you use look-around or other "fancy" non-regular features.

[priyankat99]

ended up adding split / replace functions if you could take a look at the PR whenever you have the time!
just ported over the logic from re_bytes.rs from the rust/regex library and tested the functions to verify they work

[zong-zhe]

Hi @priyankat99 , I would like to know what is wrong with this PR and when can I use this PR, #27, / replace functions is blocking my work.

[priyankat99]

hi @zong-zhe i dont think anything is wrong with the PR, it just never got reviewed. ive been using the replace and split functions for a while and its working just fine

feel free to use my branch of pcre2 for the replace functions by adding this to your Cargo.toml

pcre2 = { git = "https://github.com/priyankat99/rust-pcre2", tag = "0.0.3"}