gh-129117: Expose _PyUnicode_IsXidContinue/Start in unicodedata

[StanFromIreland]

• Issue: unicodedata module needs way of accurately determining XID_START and XID_CONTINUE properties. #129117

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📚 Documentation preview 📚: https://cpython-previews--140269.org.readthedocs.build/

[vstinner]

@StanFromIreland StanFromIreland requested a review from vstinner

I don't know these Unicode properties. The PR documentation doesn't help me:

Return True if the character has the XID_Start property

What does it mean XID_Start?

[StanFromIreland]

Ah no worries then. You can find their documentation in this report, I can add a link to it in the docs.

[vstinner]

In short, these functions check if a character is an identifier start or an identifier character according to Unicode TR31?

[StanFromIreland]

Yes.

[malemburg]

LGTM now

[StanFromIreland]

I have made the requested changes; please review again

[bedevere-app]

Thanks for making the requested changes!

@malemburg: please review the changes made to this pull request.

[malemburg]

Thanks, @StanFromIreland
This looks pretty complete now.

[StanFromIreland]

Thanks for the reviews!

[vstinner]

The change is correct, but I'm not convinced that we have to expose this feature in Python. It seems to be an Unicode feature which rarely used.

[malemburg]

Have a look at https://peps.python.org/pep-3131/ for why these are important to have.

[vstinner]

About function names, the Unicode annex has also ID_Start and ID_Continue. The XID is a variant. Maybe we should keep x in the function names?

[StanFromIreland]

About function names, the Unicode annex has also ID_Start and ID_Continue.

Note that they explicitly recommend the "X" variants.

[malemburg]

Maybe we should keep x in the function names?

You have a point there. Let's keep the "x" in "xid" for the functions to not cause confusion.

[vstinner]

LGTM

[StanFromIreland]

Thanks for merging!