Unable to use regex expression

[TheFern2]

I have search the webz and I think maybe the problem is string escaping but I am not 100% sure since is working in python3.10 just fine. I have read some posts about another RE library for micropython but I was unable to figure out how to install it with mip (re-pcre) maybe it doesn't exists anymore. https://forum.micropython.org/viewtopic.php?t=5398

I have strings like this where it should match square brackets:

BaseBOOLArray[2]
MyTag[0].UDTMember[4]

array_pattern = re.compile('\[([\d]|[,]|[\s])*\]')
index = array_pattern.search(tag).group(0)

Can anyone point me into what I am doing wrong. Running micropython v1.19 latest on main branch unix port.

[scruss]

MicroPython's [u]re module is very small. The re-pcre module is old and is no longer in micropython-lib. MicroPython is a subset of an older Python than 3.10.

What are you looking for? \[.+\] will match square bracket groups (or \[[^\]]+\] if you're cautious). I don't think we have PCRE's pipe matching at all.

[git-n-pissed]

Btw what is a good way to search for libraries available for mpy, pypy site?

The lib directory of the MicroPython project has all the libraries that have been officially ported over. You can add them to your project by including/requiring them in your manifest. See https://docs.micropython.org/en/latest/reference/manifest.html

For non-official libraries, I don't know if there is a better way to find them than doing a search on Google, GitHub (starting in these discussions), or the old MicroPython forum. Maybe a good idea for someone to start keeping an organized list though, there are quite a few!

[TheFern2]

Ah ok thanks @git-n-pissed I am brand new to the micropython world, and just trying to see what's out there I am a collaborator on a python lib and I am working on the port for micropython at the moment.

[mattytrentini]

A couple us also maintain the Standard Library Coverage wiki page. It attempts to indicate the status of all the Python libraries implemented for MicroPython.

(Happy to have more contributors too!)

[mattytrentini]

I'm also confused as to why your regex didn't work - it could be simplified but I believe all the match tokens you've used are valid for MicroPython. \d and | should work, but maybe the structure of that particular regex is causing grief..?

I'll try and dig into it a little further - mostly because I'd like to understand and document if there's a difference here - but I'm glad you have a workaround.

[TheFern2]

Yes, our library pylogix had that specific regex for ages, now that I'm making sure it works in micropython I found that \d wasn't working, someone in our discord suggested to use 0-9 and to my surprise it worked. Strange indeed. Lemme know if you find different results.

[peterhinch]

For users seeking unofficial libraries see awesome micropython.

[jimmo]

@TheFern2 Sorry about the delay responding...

The issue here is that Python supports using named character classes (e.g. \d) inside character classes (e.g. [0-9]). I guess the idea is that you can write [x\d] to support "x or digit" as a shorthand for [x0-9].

You've used [\d] but for MicroPython you need to just write \d (and it would behave equivalently in Python).

[jimmo]

I just realised this is a known issue (with a PR to implement it) -- see #7922 and #7920

[TheFern2]

Thanks for the response. As it turned out one of our discord community members was a regex expert and he contributed to the regex we ended up using which is compatible with python and mpy.