Use JLine3

[som-snytt]

Minimal changes to support new API,
with basic completion and history.
JLine handles continuation line edit.

Gets the ball rolling finally.

• Backend, nail down interface and protocol
• Colorization
• Excise old continuation handling
• History and related features
• Compile to functions, frontend manages inputs
• Coursier convenience
• Hook up -x formatting and contribute to jline
• Fix // print
• Support camel-cased, anagram-style completion as previously

Fixes scala/bug#11367

[retronym]

Thanks for this.

It's nice that autocomplete doesn't burn lines of console anymore, the options are updated in-place on subsequent typing. now takes you into the matrix of completions to navigate with a cursor. Previously, we'd detect and emit the signature for the first candidate. I'm sure JLine3 has a better way to render this, perhaps in a status bar.

I noticed that ^A ^E no longer go to line start/end all the time. It's probably worth extracting a self-contained, Java-written version of the basic way we rig up JLine in readiness to get support on the JLine mailing list.

[SethTisue]

is there anything here that must land early, e.g. in 2.13.0-RC1, in order for the rest to land later in some 2.13.x (perhaps x=0, who knows?)

[allanrenucci]

Here is the implementation in Dotty for reference. I believe it would be straigforward to port our syntax highlighter

[som-snytt]

I would accept a hint about how I might have broken

tools.test.osgi.reflection.toolbox.ReflectionToolBoxTest.basicMirrorThroughOsgi

Error Message

java.lang.ClassNotFoundException: scala.tools.reflect.ToolBoxFactory cannot be found by PAXEXAM-PROBE-5cbfb121-3e82-4a02-ae19-41d33580c408_0.0.0

Stacktrace

sbt.ForkMain$ForkError: java.lang.ClassNotFoundException: scala.tools.reflect.ToolBoxFactory cannot be found by PAXEXAM-PROBE-5cbfb121-3e82-4a02-ae19-41d33580c408_0.0.0
	at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:508)

[adriaanm]

We'll take care of the random breakage, I'm happy for you to focus on the core of the jline upgrade.

[som-snytt]

I need the green check before I take a step into the mine field. (For now, I'll branch and add features over the pit of quicksand.)

[adriaanm]

The osgi minefield looks clear after

diff --git a/build.sbt b/build.sbt
index 21b1f1c..ebf67b7 100644
--- a/build.sbt
+++ b/build.sbt
@@ -457,7 +457,14 @@ lazy val compiler = configureAsSubproject(project)
       "-doc-root-content", (sourceDirectory in Compile).value + "/rootdoc.txt"
     ),
     Osgi.headers ++= Seq(
-      "Import-Package" -> ("jline.*;resolution:=optional," +
+      "Import-Package" -> ("org.jline.keymap.*;resolution:=optional,"+
+                           "org.jline.reader.*;resolution:=optional,"+
+                           "org.jline.style.*;resolution:=optional,"+
+                           "org.jline.terminal;resolution:=optional,"+
+                           "org.jline.terminal.impl;resolution:=optional,"+
+                           "org.jline.terminal.impl.jansi.*;resolution:=optional,"+
+                           "org.jline.terminal.spi;resolution:=optional,"+
+                           "org.jline.utils;resolution:=optional,"+
                            raw"""scala.*;version="$${range;[==,=+);$${ver}}",""" +
                            "*"),
       "Class-Path" -> "scala-reflect.jar scala-library.jar"

I don't think we're going to get a ✅ on shipping the LGPL jna library, so we should also drop that dependency. It looks like jansi is all we need? I pushed these diffs to jline3 on my fork (test run: https://scala-ci.typesafe.com/job/scala-2.13.x-validate-main/6696/)

[adriaanm]

Just one test failure in that run, btw: test/files/run/repl-paste-parse.scala.

[som-snytt]

Right, that was just output order because of ripping out startup dance. I'll PR with updates and more acceptable functionality.

[adriaanm]

Excellent, thank you. Let me know if there’s other minefields I can throw myself at :-)

[smarter]

I don't think we're going to get a white_check_mark on shipping the LGPL jna library, so we should also drop that dependency.

JNA can be used as Apache2: https://github.com/java-native-access/jna/blob/16aac5fcac290ac05804da222e779e2dba365aa5/LICENSE#L1-L6

[som-snytt]

Thanks. BTW, I just checked out this branch locally to push it over the line, or over the cliff. The current REPL is totally unusable in comparison. :)

[SethTisue]

At a coffeeshop in Bern today I was openly drooling at the prospect of getting JLine 3 support in Scala 2. I think the other patrons were staring.

[SethTisue]

At a coffeeshop in Bern today I was openly drooling at the prospect of getting JLine 3 support in Scala 2.

Strangely enough, I will be at a coffeeshop in Bern again tomorrow, almost exactly one year later, again drooling over the same thing.

Residents of Bern: “THAT guy again?"

[SethTisue]

I've now been through this PR and extracted remaining TODOs at https://github.com/scala/scala-dev/labels/t%3Ajline3