YAML parser implementations

[ntrp]

Initial port, I just copied the old code and fixed compilation issues, will refine it since the base API changed since we implemented it.

My Scala knowledge sucks so if you have any suggestions they are welcome since currently I have the feeling I am using the Scala APIs totally wrong.

The test is failing (and it's poorly written), will refactor and fix in the next days.

[simplesteph]

Thanks for this first draft, some early comments

I would need some more documentation on how the format works, as well as edits to CHANGELOG.md and README.md (in the bottom).

[ntrp]

So I managed to find some time and armed with some Haskell concepts I aquired in the meantime I am now finally integrating the changes..

I have to fix all the tests because I needed to refactor how the correct parser is selected. There are still some open points like:

• is this implementation satisfiying (I know is a little Java biased)
• Should we add some additional flexibility like forcing the use of only one source?
• Do you have any implementation preference (not being a Scala developer I write Java biased code)

[ntrp]

I will edit the README, CHANGELOG, and others when the PR is ready for review

[ntrp]

@simplesteph whenever you have a moment, have a look on it and give me some feedback so I can complete the PR and finally merge

[simplesteph]

Looks great! Can you merge the changes from master please?

[ntrp]

Ok I have rebased against master and now I am fixing the tests

[mbaechler]

Hi,
Your contribution looks nice.
I have some minor comments if you don't mind looking at them.

[mbaechler]

In Scala, we usually build an ADT (you can find a lot of documentation on the web) to express different status.
Here, I would write:

sealed trait SourceAclResult
case class Success(result) extends SourceAclResult
case class Failure(errors: List[ParserException]) extends SourceAclResult

you can keep the monoid, of course, but it will be much easier to read

[ntrp]

I used this pattern to make it possible to easily use combineAll to merge the list of ACLs, can that be done with that approach?

If yes could you suggest how?

[mbaechler]

maybe something like that would work:

implicit val monoid: Monoid[SourceAclResult] = new Monoid[SourceAclResult] {
    override def empty: Success = Success.empty
    override def combine(
        x: SourceAclResult,
        y: SourceAclResult
    ): SourceAclResult = (x, y) match {
      case (Success(_), Failure(errors)) =>
        Failure(errors)
      case (Failure(errors), Success(_)) =>
        Failure(errors)
      case (Failure(errors1), Failure(errors2)) =>
        Failure(errors1 ++ errors2)
      case (Success(result1), Success(result2)) =>
        Success(result1 ++ result2)
  }

[ntrp]

I tried various options with ADTs but that approach was making the whole thing more complicated in some cases because I don't want to pattern match always. For example in tests I would had to use asInstanceOf I guess. I also tried a leaner approach by defining SourceAclResult as a Either[ParsingExceptions, KsmAcls] but that broke my monoid extension and I did not know how to fix it (error where not combined anymore).

In the end I simply refactored the monoid implementation to be a little more readable and I think it looks pleasant now.

[simplesteph]

Thanks a lot for this PR !

[ntrp]

Next on the list I will try to merge back directory support as soon as I have some time