Fix line positions

[JonasAlaif]

No description provided.

[JonasAlaif]

We should also add a CI test for this

[marcoeilers]

Looks good to me.
That was quick, nice!

[JonasAlaif]

@marcoeilers there is just one thing that I'm not sure about; there was a comment:

// As opposed to use Index ~ t ~ Index, this implementation is agnostic to white space specializations.

My solution is to pretty much use Index ~~ t ~~ Index (except that using exactly that didn't work for some reason) - do you know what @fabiopakk mean by this? Will we run into issues with this new version if we encounter "white space specializations" whatever that is?

[marcoeilers]

No, I don't really remember how the whitespace handling works at all. I guess you can have different parse rules being either whitespace agnostic or not, but I don't know who's specializing what where.

But I tested the code on an example that had all the whitespace-related cases I could think of and it always worked, so whatever it's doing it seems to be right.

[JonasAlaif]

The key difference is between ~ and ~~ which are used to join two parsers; for instance using the former "hello" ~ "world" would match any of "helloworld", "hello world", ..., whereas the latter "hello" ~~ "world" would only match "helloworld". I guess the concern was that with Index ~ t ~ Index the first Index could take the position at an arbitrary number of whitespaces before, not actually giving you the start of the t itself? In that case using Index ~~ t ~~ Index instead, as I do, would alleviate this concern.

[marcoeilers]

Yeah, makes sense.

[ArquintL]

@JonasAlaif Awesome, thanks a lot for the quick fix!