Improve tab completion and code assist in REPL

[retronym]

Re-enable acronym-style completion, e.g. getClass.gdm offers getDeclaredMethod[s].

Under JLine completion, move all filtering up in the UI layer. Reimplement #9510 (dealing with overloads that contain some deprecated alternatives) in the UI layer

Fix completion of keyword-starting-idents (e.g. this.for<TAB> offers formatted.

Register a widget on CTRL-ALT-T that prints the type of the expression at the cursor. A second invocation prints the desugared AST.

Enable Levenshtein based typo matching, but disable it for short strings which IMO tends to offer confusing results.

scala> scala.tools.nsc.util.EditDistance.levenshtien<TAB>

scala> scala.tools.nsc.util.EditDistance.levenshtein

Includes upgrade to JLine 3.20 (was 3.19)

[retronym]

I believe this was a latent bug in the presentation compiler. It became apparent in the REPL completion tests after I (mostly) removed the hack of inserting __DUMMY__ at the cursor in this PR.

In erroneous code, the range position of the TypeDef of an annotated parameter can contain the annotation itself. So we should always try traversing into .symbol.annotations.map(_.original).

[SethTisue]

@retronym this looks great (and feels great, I tried all the new behaviors)

One question: you've documented (in the PR description, but also in the help text in the PR) the new "show type" feature as control-shift-T, but in my terminal (Terminal app in MacOS 11.5.1), just plain control-T works, whereas control-shift-T just beeps at me. Is that not the behavior you're experiencing?

Second question: according to the JLine 3.20 release notes, they've upgraded JNA to 5.8.0: jline/jline3@8e9fc36 ; can you include that bump here, too?

No other concerns before merging.

[retronym]

just plain control-T works, whereas control-shift-T just beeps at me. Is that not the behavior you're experiencing?

Just retested. Both work for me. I've updated the docs to control-T.

I think its okay for us to hijack this keybinding. The T=type mnemonic is nice, and the existing behaviour is pretty niche.

scala> abc<C-T>def

scala> abdcef

[SethTisue]

Hmm, not sure what I think about the hijacking... I actually use control-T to swap (t for transpose?) characters, I'm accustomed to that being available. Not sure how typical I am.

[retronym]

I've changed it to CTRL-ALT-T. WDYT?

[SethTisue]

Yeah that works 👍

Did you see my suggestion about the JNA version?

[SethTisue]

fyi @eed3si9n on the JLine version bump... not sure if there are implications for sbt

[bjornregnell]

Nice features! But I think CTRL+ALT+T is so much connected to "Start terminal" in Ubuntu and flavors so this will be a big clash. I would really suggest finding something else -- everything else would be almost less of a clash even if keystrokes are overloaded...

[SethTisue]

does an .inputrc file (#9518) have the power to resolve a clash like this for an individual user?

[Sciss]

I run into missing API when updating from Scala 2.13.6 to 2.13.7 - method camelMatch has been removed. Please advise:

        def tryCamelStuff: Completion.Result = {
          // Lenient matching based on camel case and on eliding JavaBean "get" / "is" boilerplate
          val camelMatches      : List[c.Member ] = r.matchingResults(c.CompletionResult.camelMatch(_)).filterNot(shouldHide)
          val memberCompletions : List[String   ] = camelMatches.map(_.symNameDropLocal.decoded).distinct.sorted

          def allowCompletion: Boolean =
            (memberCompletions.size == 1) ||
              c.CompletionResult.camelMatch(r.name).apply {
                val pre = longestCommonPrefix(memberCompletions)
                r.name.newName(pre)
              }

          val memberCompletionsF: List[Completion.Candidate] =
            memberCompletions.map(Completion.Simple)

          if (memberCompletions.isEmpty) {
            Completion.NoResult
          } else if (allowCompletion) {
            Completion.Result(offset - r.positionDelta, memberCompletionsF)
          } else {
            // XXX TODO : why is this used in the original code, but does not appear in the results?
            //              val empty: Completion.Candidate = new Completion.Candidate {
            //                def stringRep: String = ""
            //              } // ""
            Completion.Result(offset, /* empty :: */ memberCompletionsF)
          }
        }

do I just ditch tryCamelStuff. Sadly, I don't remember the genealogy of this code, only that it no longer compiles.

[Sciss]

This was cross compiling code for Scala 2.12 and 2.13, so I have to fork that into two :-/

[SethTisue]

Sciss we don't even guarantee API stability of compiler and REPL internals between minor Scala versions, let alone between major versions. So I'm sorry for the inconvenience, but I consider it normal that you might need separate 2.12-specific and 2.13-specific code from time to time.

As for what can be done on the 2.13 side specifically: It's rather unexpected that anyone was even using camelMatch from outside, to be honest.

Does it appear to you that the logic in it was removed entirely, or was it merely refactored so that it's no longer easily accessible? If the former, perhaps you could paste the logic into your own codebase. If the latter, perhaps the REPL code could be refactored to expose it again. (As for who would do the refactoring, personally I'm inclined to say "pull request welcome" to such a refactoring, but I'm not sure what Jason's own take might be.)

[xuwei-k]

scala/bug#12491 🤔