Comment handling

[maxcountryman]

I've been working on a SQL formatter that leverages this library extensively. One problem with using sqlparser-rs right now is that comments are treated like whitespace and removed from the AST. I'm curious if there would be any interest in bringing comments into the AST? Perhaps this could be optional, since I imagine it's not terribly useful for most cases.

[nickolay]

I mentioned before that I am interested in experimenting with an alternative design, in which the parser's output can be concatenated back together to form exactly the input string. I should probably share the prototype I have, despite it being very incomplete as I seldom work on it...

I don't see another way for the comments to be retained.

[maxcountryman]

@nickolay I'd be very curious to see your prototype--if there's any way I can contribute, I'd be happy to. 🙂

[mullr]

This is /exactly/ the use case I had in mind for #161.

[nickolay]

Sorry for the delay, I posted the prototype in #189

[olalonde]

I also would like to access comments in the AST :( Any progress on this?