How to migrate this call site of Completion.Completer from 3.4.2 to 3.5.0?

[lihaoyi]

This is coming up in the Ammonite Scala 3.5.0 upgrade com-lihaoyi/Ammonite#1548:

class DeepCompleter(
    mode: Completion.Mode,
    prefix: String,
    pos: SourcePosition
  ) extends Completion.Completer(mode, prefix, pos)

The new signature seems totally different: prefix is gone, and it takes a matches callback.

How what does the new signature mean, and how do I adapt the old use site to fit the new signature?

Thanks!

[lihaoyi]

Setting matches to _.startsWith(prefix) seems to make my tests pass, but is that the right thing to do? And what's this new untpdPath: List[untpd.Tree] parameter meant to be?

[tgodzik]

I think these changes were made so that we can do a fuzzy match instead of just prefix one. Doing _.startsWith should be equivalent to the previous behaviour.

The untpdPath might be needed for cases with extensions where we want to get the parsed tress instead of the desugared ones

@rochala can probably add more

[rochala]

The new fields were added as necessary optimizations for presentation compiler, so we don't recompute those fields. I've left the original method in Completion.scala so feel free to use it if you don't have fields precomputed:

scala3/compiler/src/dotty/tools/dotc/interactive/Completion.scala

Line 55 in 4891858

def completions(pos: SourcePosition)(using Context): (Int, List[Completion]) =

[rochala]

The API of the interactive package in dotty will evolve over time. It is still internal API. I'm trying to keep the backward compatibility, but I recommend that you migrate to the actual presentation compiler in the future. You may not need all the features, but it is way richer with features such as case completions, Scala-CLI / ammonite directives completions etc. It is also very easy to plug in. If you're interested I can help you with that / or check Scastie as it also relies on the presentation compiler. It is also MiMa tested so you shouldn't have any issues in the near future.

[rochala]

And if you want to use the Completion.Completer untpdPath is computed by running: https://github.com/rochala/dotty/blob/0b45f44092d9c00f2e3f89d08eabccb42d78ad67/presentation-compiler/src/main/dotty/tools/pc/completions/CompletionProvider.scala#L61 and matches is a predicate used to filter completions. You can provide your own fuzzy matcher or just do _.startsWith as Tomasz suggested