How do I use `TemplateLanguage` to inject syntax into Java comments?

IntelliJ Platform
1

I’m creating a plugin that injects custom syntax in Java & Kotlin comments.
The initial implementation had an com.intellij.lang.InjectableLanguage, which was added in PsiComment elements. The downside is that the AST my parser created was separate from the original file, so I couldn’t access comment’s injected AST from other comments.
I was suggested to look into com.intellij.psi.templateLanguages.TemplateLanguage functionality and I used the Handlebars plugin as a reference.
The current issue is that my lexer receives the entire Java file. What do I need to do to make it detect Java comments and use my lexer and parser only for those? The plugin code is available on GitHub. (Unfortunately I can’t add links to specific files, but all relevant implementation is in the linked directory)

2

Hello.

I’ve implemented language injection several times: in PHP strings and in Cron plugin.
Both time I did it with multiHostInjector extension point.

multiHostInjector allows you to mark suffixes (start / end) and text range inside the element. I think this is what you are looking for:

  • Check if the PsiComment suites your custom syntax
  • Find start and the end of the syntax
  • And inject custom language

The main thing of language injecting is the target psi element must implement PsiLanguageInjectionHost

3

I’ve implemented MultiHostInjector with

class StitcherInjector : MultiHostInjector, InjectionBackgroundSuppressor {
    private val comments: List<Class<out PsiElement>> = listOf(PsiCommentImpl::class.java)

    override fun getLanguagesToInject(registrar: MultiHostRegistrar, context: PsiElement) {
        if (context is PsiLanguageInjectionHost && context.isStitcherComment) registrar
            .startInjecting(StitcherLang)
            .addPlace(null, null, context, ElementManipulators.getValueTextRange(context))
            .doneInjecting()
    }

    override fun elementsToInjectIn(): List<Class<out PsiElement>> = comments
}

@Suppress("UnstableApiUsage")
class StitcherFileTypeOverrider : FileTypeOverrider {
    override fun getOverriddenFileType(file: VirtualFile): FileType? =
        if (file is LightVirtualFile && file.language == StitcherLang) StitcherFile.StitcherFileType else null
}

However, this doesn’t fix the issue. The injected elements are in their own PsiFile-s, so I can’t access other snippets. I’m using the PsiViewer plugin to inspect the parsed structure, but it can’t access the comment syntax.

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