Add file dependencies to the the output

[johnynek]

closes #60

This is for suggestions and discussions on how to improve.

There are no new tests that parsing works (and I don't think it does). I will add those after we agree on the basic direction. The current Integration tests also fail since they are not expecting the file output.

Thanks for taking the time to review.

cc @SethTisue

[johnynek]

@SethTisue any feedback on this approach?

[SethTisue]

@johnynek I'm sorry I haven't managed to reply to you about this yet :-(

it's very near the top of my queue, I'm just a little overwhelmed right now with Scala 2.13.0-M5 related stuff.

[SethTisue]

what do you think about a different approach where instead of adding new edges, we just change

case class Entity(name: String, kind: EntityKind)

to

case class Entity(name: String, kind: EntityKind, path: java.io.File)

then in Entity#forSymbol we'd change

    Entity(sym.nameString, kind)

to

    Entity(sym.nameString, kind, sym.associatedFile.canonicalPath)

that said, the design in this PR seems plausible to me also. so I'm just throwing this other possibility out there, but I'd consider the change mergeable regardless of which path you decide to go down.

[johnynek]

Hey @SethTisue I had a bit of energy so I was going to look at this again. Your suggestion breaks all the existing tests because now all entities have to have a path encoded. If anyone serialized any output, they would all be broken unless paths are optional, which makes additional complexity.

The next issue is that the graph of using probably shouldn't have the file information on each entity. Like sym: foo in filex "uses" sym: y in filez seems redundant since you can join the symbol information to see which file declared the symbol.

You probably have a lot more opinions about how to get this information out, maybe the easiest thing for me in the short run is just to use my patch and you can decide if/how you want to expose this information?

[SethTisue]

(I'll have to think about this in early January.)

[SethTisue]

@johnynek yeah, I like your way, I'm convinced. happy to merge this if you can get CI to sign off.