Generate trees for Kotlin using the `kotlin-compiler-embeddable` parser

[tsantalis]

The tree-sitter parser for Kotlin is quite unreliable.

In many cases, it generates ERROR nodes (more details in the issue below)
bonede/tree-sitter-ng#108
and it also parses functional interfaces as functions.

I would strongly recommend to use kotlin-compiler-embeddable
https://mvnrepository.com/artifact/org.jetbrains.kotlin/kotlin-compiler-embeddable/versions?repo=central
for generating the AST.

It provides a org.jetbrains.kotlin.psi.KtVisitor

Parsing is easy as follows:

String filePath = ""; // the path of a kt file
String fileContent = "" // the string content of a kt file
KotlinCoreEnvironment environment = KotlinCoreEnvironment.createForProduction(
  	Disposer.newDisposable(),
  	new CompilerConfiguration(),
  	EnvironmentConfigFiles.JVM_CONFIG_FILES
);
PsiFileFactoryImpl factory = (PsiFileFactoryImpl) PsiFileFactory.getInstance(environment.getProject());
PsiFile psiFile = factory.createFileFromText(filePath, KotlinLanguage.INSTANCE, fileContent);
KtFile ktFile = (KtFile)psiFile;

[jrfaller]

Hi @tsantalis, good find! It seems that the only required code to write is a convertor from a PSI tree to a GumTree tree it should be too hard.

[tsantalis]

@jrfaller Thank you for considering this feature.
The doc for KTVisitor

https://fossies.org/dox/kotlin-2.3.20/classorg_1_1jetbrains_1_1kotlin_1_1psi_1_1KtVisitor.html

visitKtElement(@NotNull KtElement element, D data)
is perhaps the method to override, as KtElement is the super-interface for all Kotlin AST nodes.

[jrfaller]

Nice! I think you spotted the best method to override, thanks!