Minor request: \v for vertical spacing

[dchaplinsky]

Hi!

I'm using the regex lib to make a port of language tool libs (originally java) for sentence and word tokenization.
Those are relying on \v\h heavily. Some of those rules are shipped in the xml files full of regexes and I'm willing not to alter those to not to maintain a separate copy. I can kind of workaround it by replacing \v with VERTICAL_SPACE: str = "\u000a\u000b\u000c\u000d\u0085\u2028\u2029" but it's another tiny nightmare, as those regexes can come in different fashions: \v*, [\v\t]*, etc.

Please review the possibility to add the \v flag

[dchaplinsky]

I can see that code suggest \v pseudo, but I cannot understand why it doesn't work then:

In [3]: import regex as re

In [8]: re.search(r"\v", "\n") is None
Out[8]: True

In [9]: re.search(r"\v", "\n", flags=re.M | re.U | re.V1) is None
Out[9]: True

[mrabarnett]

\v already exists in Python as being short for \x0b (LINE TABULATION):

>>> '\v'
'\x0b'
>>> '\v' == '\N{LINE TABULATION}'
True

[dchaplinsky]

Thanks for the prompt reply!

Any ideas on the matching of vertical space?

[mrabarnett]

There are far fewer characters that need to match: [\x0A\x0B\x0C\x0D\x85\u2028\u2029] or [\x0A-x0D\x85\u2028\u2029].

Maybe it could be added as \V, although that would be inconsistent with \h, and there are pairs of lowercase/uppercase escape codes where the uppercase one is the negative of the lowercase one, e.g. \d and \D. On the other hand, those implementations that have \h and \v don't have \H and \V.

Also, I don't want to add something that the re module might do differently if it were added later.

That's why it hasn't been added already.

[dchaplinsky]

Okay, makes perfect sense (still sad for my downstream task).

…

On Tue, Aug 16, 2022 at 5:18 PM mrabarnett ***@***.***> wrote: There are far fewer characters that need to match: [\x0A\x0B\x0C\x0D\x85\u2028\u2029] or [\x0A-x0D\x85\u2028\u2029]. Maybe it could be added as \V, although that would be inconsistent with \h, and there are pairs of lowercase/uppercase escape codes where the uppercase one is the negative of the lowercase one, e.g. \d and \D. On the other hand, those implementations that have \h and \v don't have \H and \V. Also, I don't want to add something that the re module might do differently if it were added later. That's why it hasn't been added already. — Reply to this email directly, view it on GitHub <#477 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABAA4WMEYPZUNSUUHPGUF3VZOPMJANCNFSM56TVAIOQ> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[mrabarnett]

I've come across a mention of \H and \V, so using \V would be a bad idea.

[dchaplinsky]

Maybe something like a pseudo-character class, like [:blank:]?

…

On Tue, Aug 16, 2022 at 9:39 PM mrabarnett ***@***.***> wrote: I've come across a mention of \H and \V, so using \V would be a bad idea. — Reply to this email directly, view it on GitHub <#477 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABAA4UITGW7KYVBY4FVE7DVZPN43ANCNFSM56TVAIOQ> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[mrabarnett]

Now I'm thinking about \y and \Y, which look a little like \v and \V. ProgressSQL uses them instead of \b and \B, which every other implementation that I know of uses, possibly because \b normally represents \x08 outside regex, and does still within characters classes.

I want the regex module to remain compatible with the re module, and just in case they ever get added there in the future, I'm soliciting opinions on python-dev.

[mrabarnett]

I've added \p{HorizSpace} (\p{H}) and \p{VertSpace} (\p{V}) in regex 2022.8.17, which is currently being built on GitHub and should arrive on PyPI soon.

[dchaplinsky]

Wow, many thanks!

[dchaplinsky]

Well, you can probably add it to V1? It's already somewhat beyond the original re :)

…

On Tue, Aug 16, 2022 at 11:29 PM mrabarnett ***@***.***> wrote: Now I'm thinking about \y and \Y, which look a little like \v and \V. ProgressSQL uses them instead of \b and \B, which every other implementation that I know of uses, possibly because \b normally represents \x08 outside regex, and does still within characters classes. I want the regex module to remain compatible with the re module, and just in case they ever get added there in the future, I'm soliciting opinions on python-dev. — Reply to this email directly, view it on GitHub <#477 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABAA4VV4QEAN2LIUDUDSXTVZP2ZNANCNFSM56TVAIOQ> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[mrabarnett]

Given the feedback on python-dev, I won't be adding \y and \Y. What I've already added should suffice.

[dchaplinsky]

Totally works for me! Thanks a lot for looking into it again!

…

On Tue, Oct 11, 2022 at 8:14 PM mrabarnett ***@***.***> wrote: Given the feedback on python-dev, I won't be adding \y and \Y. What I've already added should suffice. — Reply to this email directly, view it on GitHub <#477 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AABAA4VDSYGNLFNU37PSGS3WCWN7JANCNFSM56TVAIOQ> . You are receiving this because you authored the thread.Message ID: ***@***.***>