How do I pass cutom Launcher for LanguageServerDefinition?

[yanshudan]

context: I need to custom a type adapter to handle responses from language server eclipse-lsp4j/lsp4j#865, and it turned out I need to pass a custom gson builder to a launcher builder like below:

var launcher = new Launcher.Builder<LanguageClient>()
          .setLocalService(myserver)
          .setRemoteInterface(LanguageClient.class)
          .setInput(System.in)
          .setOutput(System.out)
          .configureGson(gsonBuilder -> gsonBuilder
              .registerTypeAdapterFactory(new MyProgressParamsAdapter())) //register custom adapter
          .create();

      launcher.startListening();

But in

lsp4e/org.eclipse.lsp4e/src/org/eclipse/lsp4e/LanguageServerWrapper.java

Lines 365 to 372 in a096dad

	Launcher<LanguageServer> launcher = serverDefinition.createLauncherBuilder() //
	.setLocalService(languageClient)//
	.setRemoteInterface(serverDefinition.getServerInterface())//
	.setInput(lspStreamProvider.getInputStream())//
	.setOutput(lspStreamProvider.getOutputStream())//
	.setExecutorService(listener)//
	.wrapMessages(wrapper)//
	.create();

lsp4e creates a launcher already, and I suppose I need to pass my custom launcher to make it work.

serverDefinition.createLauncherBuilder() //returns my custom builder

But the class is abstract static &private, I cannot override createLauncherBuilder by extending the class or using dynamic proxy.

lsp4e/org.eclipse.lsp4e/src/org/eclipse/lsp4e/LanguageServersRegistry.java

Line 213 in a096dad

public <S extends LanguageServer> Launcher.Builder<S> createLauncherBuilder() {

How could I resolve this?

[rubenporras]

@mickaelistria,

I assume the analysis is correct so far and that @yanshudan needs a custom Gson configurator.

What do you think of adding

				.configureGson(serverDefinition.getConfigureGson())

to

lsp4e/org.eclipse.lsp4e/src/org/eclipse/lsp4e/LanguageServerWrapper.java

Lines 365 to 372 in a096dad

	Launcher<LanguageServer> launcher = serverDefinition.createLauncherBuilder() //
	.setLocalService(languageClient)//
	.setRemoteInterface(serverDefinition.getServerInterface())//
	.setInput(lspStreamProvider.getInputStream())//
	.setOutput(lspStreamProvider.getOutputStream())//
	.setExecutorService(listener)//
	.wrapMessages(wrapper)//
	.create();

and then the corresponding extension point to languageServer.xsd? The configureGson would by default do nothing to be backwards compatible.

Or do you have a better idea?

[mickaelistria]

I don't have a better idea, this proposal seems good.

[rubenporras]

@yanshudan , would you like to prepare a PR for the proposal?

[yanshudan]

@rubenporras Yes, sure. Will get back to you when the PR is ready.

[yanshudan]

Hi @rubenporras , I'm working on the PR and I'm wondering how I could pass a custom gson builder in my code once the PR gets merged.

[yanshudan]

I noticed

new Launcher.Builder<LanguageClient>()
          .setLocalService(myserver)
          .setRemoteInterface(LanguageClient.class)
          .setInput(System.in)
          .setOutput(System.out)
          .configureGson(gsonBuilder -> gsonBuilder
              .registerTypeAdapterFactory(new MyProgressParamsAdapter()))

returns a Launcher.Builder and lsp4e provides extesion point for that

lsp4e/org.eclipse.lsp4e/src/org/eclipse/lsp4e/LanguageServersRegistry.java

Line 213 in 1a442b8

public <S extends LanguageServer> Launcher.Builder<S> createLauncherBuilder() {

if I understand correctly, I can just provide my launcher in some way. Looks like the proposed solution also leverages the extension point mechanism to customize a gson builder, why not just customize a launcher?

[mickaelistria]

@yanshudan good finding. Indeed it looks like you can try to define your own launcher builder, and get this particular class setting the appropriate gson configuration during that .build() method.

[rubenporras]

Agree, if that works, that is better.