(csv) Add a `CsvParser.Feature.SKIP_EMPTY_LINES` to allow skipping empty rows

[cowtowncoder]

Looks like a commonly supported option with CSV (family of formats) is to allow skipping of empty rows; that is, ones that only contain white-space.

[cowtowncoder]

note: Original had 5 thumbs-up, couple of +1s. So highly requested.

[kg29]

Is anyone working on this? I would be happy to pick it up.

[cowtowncoder]

@kg29 No one is workign on this as far as I know, so help would be highly valued!

[kunickiaj]

This is the only thing preventing us from switching from commons-csv.

[cowtowncoder]

@kunickiaj One thing that could help (I may have time to look into this after completing non-blocking json parser) would be a failing unit test that simply shows how you'd like this to work. That is, test that would pass after fix.

[kunickiaj]

Yeah, I may look into this once I get a free moment.

We did some benchmarks against jackson csv + guard clause on our side vs commons-csv and it pretty much wiped out any performance gains from moving to jackson.

Figure fixing it here should be a much better option.

[kunickiaj]

Here's a trivial test which would pass given the desired behavior.

https://github.com/kunickiaj/jackson-dataformats-text/commit/b34aa58b5cb0a6926485d70fc17d2bc296eac925

[cowtowncoder]

Excellent thank you; I'll have a look.

[cowtowncoder]

Quick note: I think this makes more sense as CsvParser.Feature than CsvSchema setting since it's not as much a property of document than handling (although I can see why someone might argue otherwise too). But I think this is more convenient from user perspective.