scalameta/scalameta

Library to read, analyze, transform and generate Scala programs

Ólafur Páll Geirsson

@olafurpg

in what situation would you like to add positions?

Roman Janusz

@ghik

@olafurpg ugh, that's bad. I thought it would be a pretty essential thing. In my case I need to do some cosmetic transformation on parsed tree but I don't want to lose position information.

Roman Janusz

@ghik

Actually, this particular case is probably a bug: a +: (1,2,3) - this is parsed by scalameta as ApplyInfix with three parameters but scalac parses (1,2,3) in this context as a tuple. So I wanted to workaround this by creating a Tuple tree out of these arguments but apparently I can't do this without losing positions.

I mean, I won't lose positions on arguments themselves but I would like the tuple to have a position, too.

Aliaksei Chapyzhenka

@drom

Hello, I am using sclameta-parsers from NPM. Any chance to get AST serialization portion as NPM package?

here is my ticket scalameta/scalameta#1867

Pedro Rodriguez Tavarez

@pjrt

Hey, what ever happened to scalameta macros?

Is that still a thing?

Roman Janusz

@ghik

@pjrt no, scalameta is now only about tooling

Roman Janusz

@ghik

Am I correct that when I call .tokens on a tree, it tokenizes the input from scratch every single time?

Ólafur Páll Geirsson

@olafurpg

@ghik the tokens are cached

this cache has historically been global and caused a lot of headache, but I made this cache local in scalameta/scalameta#1914

Roman Janusz

@ghik

ok great, thanks

Roman Janusz

@ghik

I'm trying to open the scalameta project in VS Code with metals and I'm consistently getting error from sbt: Not a valid command: metalsEnable. I tried various workarounds found in already reported issues (e.g. scalameta/metals#685) but nothing works...

Ólafur Páll Geirsson

@olafurpg

@ghik you might want to try using the latest SNAPSHOT

otherwise, I don't import the scalameta build into metals since it conflicts with the SemanticDB plugin (which is developed in the scalameta build and Metals uses it)

we do funky stuff like customize the sourceroot setting to be a subdirectory, which doesn't play nicely with Metals

Jiuyang Liu

@sequencer

Hello, I wonder how to implement a "find usage" Scala? since after AST generation, there won't be any packages information for codes. Is there any compiler plugin to help me with this?

Ólafur Páll Geirsson

@olafurpg

@ghik I was able to get Metals working in the Scalameta build using the latest Metals SNAPSHOT

Ólafur Páll Geirsson

@olafurpg

@sequencer you can use the SemanticDB compiler plugin to emit protobuf data with symbol references

you'll need a bit more work to handle references to overridden methods

You can poke into the Metals codebase to see how "textDocument/references" is implemented

Jiuyang Liu

@sequencer

OK! Thank you! I'll try.

Roman Janusz

@ghik

@olafurpg thanks, will try it out

Ólafur Páll Geirsson

@olafurpg

We’re hopefully doing a stable release in a couple days if you can hold out the wait

Roman Janusz

@ghik

@olafurpg I still can't make it work with current snapshot. I built 0.7.7-SNAPSHOT from today's master and I'm getting this:

java.util.concurrent.ExecutionException: org.eclipse.lsp4j.jsonrpc.ResponseErrorException: DecodingFailure(Attempt to decode value on failed cursor, List(DownField(providesFileWatching), DownField(capabilities)))
    at java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
    at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1915)
    at scala.meta.internal.metals.BuildServerConnection$.initialize(BuildServerConnection.scala:176)
    at scala.meta.internal.metals.BuildServerConnection$.fromStreams(BuildServerConnection.scala:129)
    at scala.meta.internal.metals.BloopServers.$anonfun$newServer$1(BloopServers.scala:71)
    at scala.util.Success.$anonfun$map$1(Try.scala:255)
    at scala.util.Success.map(Try.scala:213)
    at scala.concurrent.Future.$anonfun$map$1(Future.scala:292)
    at scala.concurrent.impl.Promise.liftedTree1$1(Promise.scala:33)
    at scala.concurrent.impl.Promise.$anonfun$transform$1(Promise.scala:33)
    at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:64)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.eclipse.lsp4j.jsonrpc.ResponseErrorException: DecodingFailure(Attempt to decode value on failed cursor, List(DownField(providesFileWatching), DownField(capabilities)))
    at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.handleResponse(RemoteEndpoint.java:209)
    at org.eclipse.lsp4j.jsonrpc.RemoteEndpoint.consume(RemoteEndpoint.java:193)
    at org.eclipse.lsp4j.jsonrpc.json.StreamMessageProducer.handleMessage(StreamMessageProducer.java:194)
    at org.eclipse.lsp4j.jsonrpc.json.StreamMessageProducer.listen(StreamMessageProducer.java:94)
    at org.eclipse.lsp4j.jsonrpc.json.ConcurrentMessageProcessor.run(ConcurrentMessageProcessor.java:113)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

Ólafur Páll Geirsson

@olafurpg

@ghik you may have an old version of bloop running

our CI publishes a SNAPSHOT on every merge BTW http://scalameta.org/metals/docs/editors/vscode.html#using-latest-metals-snapshot

we're waiting for a stable release of bloop to come out before releasing metals v0.8

maybe best to wait until then

Roman Janusz

@ghik

ok, thanks, that's probably what I will do

but I don't understand why I'm running wrong version of bloop - isn't it set up automatically by metals?

Tomasz Godzik

@tgodzik

@ghik might also be needed to reimport the build - that message usually means that some json has an unexpected structure

Jakub Kozłowski

@kubukoz

I'm having trouble running scalafifx on a project (RemoveUnused) - using the sbt plugin/task. The plugin claims the files were changed but they remain unmodified...

sbt:OrderService> scalafix RemoveUnused
[info] Running scalafix on 10 Scala sources
[info] Running scalafix on 6 Scala sources
[info] Running scalafix on 3 Scala sources
[info] Running scalafix on 50 Scala sources
[success] Total time: 1 s, completed Dec 17, 2019 12:35:41 PM

yet nothing changes

I have the necessary flags on, and can see warnings on a fresh compile

would appreciate any hints

sandeshyapuram

@pandareen

Hello, can you point me to some examples? I could use some full-blown tutorials

Bartosz Bąbol

@BBartosz

According to main page of scalameta: Scalameta- Library to read, analyze, transform and generate Scala programs -> how exactly scalameta is used to generate scala programs since macros are not part of scalameta anymore?

Gabriele Petronella

@gabro

@BBartosz you can generate programs by constructing trees and printing them with Scalameta. Macros allow you to do roughly the same thing, except you do it during the compilation of your program

in other words, you can do code generation with Scalameta

(I use it for this purpose at work)

Ólafur Páll Geirsson

@olafurpg

@BBartosz Scalameta does not support macros, you can use scala-reflect macros instead

Roman Janusz

@ghik

Hi!
I have an already parsed Source. I also have a Position representing some arbitrary range in that source. I would like to obtain Tokens representing tokens only from that range. How can I do this efficiently?

Is there anything better I can do than manually implementing binary search?

Ólafur Páll Geirsson

@olafurpg

You can access the underlying token array by using a package private API called “Origin”

But you would still need to know the index in the array where your range starts

So binary search is the best solution if you already have the token array.

Roman Janusz

@ghik

Thanks

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