First contact: got Daffodil connected to VS Code debugger via DAP

[arosien]

I've got a super-basic "step debug a parse using VS Code via DAP" working (see attached animated gif). It relays the current schema--no "stack" yet--and data position. Stepping works, but I haven't implemented "continue" + "pause" yet.

[arosien]

I've added more daffodil state to the "Variables" pane and now correctly handle looking at the state of the "schema stack" trace.

[arosien]

Also pushed a working Pause/Continue in #12. If you have a small data file you need to press it quick!

[arosien]

I've got setting and updating breakpoints working:

[arosien]

Trying current data region as DAP "output event", whacha think?

[arosien]

Oh, I didn't commit this! I can if that works for folks.

[jw3]

I think it provides a great entrypoint to talking about the custom views that are needed. "We have this data on the backend and can send it over, need to build displays for it..." There are of course other implementation details we have to work through related to how it is sent, but showing the potential now is nice.

On the frontend a view that sets its text rather than appending might be a simple first custom view impl. Tying that view into an event that delivers this text would make for a good first take on this.

[arosien]

I'm happy that it didn't take much code to add this feature. Roughly:

+++ b/src/main/scala/ddb/debugger/dapodil/DAPodil.scala
@@ -353,6 +353,7 @@ object DAPodil extends IOApp {
   trait Debugee {
     def data(): Signal[IO, Data]
     def state(): Stream[IO, Debugee.State]
+    def outputs(): Stream[IO, Events.OutputEvent]
 
     def step(): IO[Unit]
     def continue(): IO[Unit]

[jw3]

Nicely done.

There are of course other implementation details we have to work through related to how it is sent

Was thinking like OutputEvent vs DaffodilInputStreamPositionEvent or variable, or whatever is best way to provide specific event for input stream position.

[arosien]

BTW the data view is just from some code I ripped out of the "legacy" InteractiveDebugger, I didn't make a hex view on my own :).

[arosien]

FYI, it's super-simple to replicate the InteractiveDebugger command-line experience, it's just an evaluate request/response in DAP. I jammed an infoset display in about 10 minutes: