Feat(parser): improved comment parsing

[mpf82]

improved comment parsing for INSERT, UPDATE, and DELETE

added tests with and w/o CTEs

[mpf82]

The build process is complaining about this line:

comments = comments if comments else None

sqlglot/parser.py:1718: error: Incompatible types in assignment (expression has type "list[Any] | None", variable has type "list[Any]") [assignment]

I am trying to make sure comments either has elements or - if the list is empty - is set to None.

I do not know how to make mypy happy, help is appreciated.

[georgesittas]

LGTM, thanks! Maybe we should also test the SQL generation for these comments?

I am trying to make sure comments either has elements or - if the list is empty - is set to None. I do not know how to make mypy happy, help is appreciated.

You can also just inline it in the self.expression call:

        return self.expression(
            exp.Insert,
            comments=comments,
            ...

You don't need to set comments to None if it's an empty list, the expression method doesn't care if it's None or [].

[mpf82]

Maybe we should also test the SQL generation for these comments?

Sadly, in all cases, the comments are moved to the end, instead of at the beginning.

I am not even sure, how select_sql achieves comments in front in the generator.

[georgesittas]

Maybe we should also test the SQL generation for these comments?

Sadly, in all cases, the comments are moved to the end, instead of at the beginning.

I am not even sure, how select_sql achieves comments in front in the generator.

There's a flag in the generator that controls this, it's called WITH_SEPARATED_COMMENTS. You should be able to fix this by updating it to contain exp.Insert etc.