Line Markers are suddenly disappearing in kotlin file (UAST).

Answered

Created August 21, 2019 12:36

As I know, line markers should be placed only on special psi elements, for example, on class name identifier. Placing the marker on the wrong element may lead to its disappearing while file editing.

I place line marker on the `uClass.uastAnchor?.sourcePsi` element. Am I doing right? In Java files, it works perfectly. But in Kotlin it is not stable. I found an example in kotlin sources (https://github.com/JetBrains/kotlin/blob/ba6da7c40a6cc502508faf6e04fa105b96bc7777/idea/idea-android/src/org/jetbrains/kotlin/android/KotlinAndroidLineMarkerProvider.kt#L56), it is without UAST, however, it references the same element.

I tried kotlin versions 31 and 41. I suppose, there is a problem with the AST comparison in kotlin (leaf elements do not match correctly after changes).

5 comments

Yann Cebron

Created August 21, 2019 13:45

Please try

1) UElement uElement = org.jetbrains.uast.UastUtils#getUParentForIdentifier(psiElement)

2) if (uElement instance UClass) PsiElement identifier = UElementKt.getSourcePsiElement(uClass.getUastAnchor())

Alexander Shustanov

Created August 22, 2019 05:15

Hi! Thank you for your reply, but it is exactly what I do :)

Yann Cebron

Created August 22, 2019 08:57

Please compare your code with this one from Devkit: https://github.com/JetBrains/intellij-community/blob/4999f5293e4307870020f1d0d672a3d35a52f22d/plugins/devkit/devkit-core/src/navigation/DevkitRelatedClassLineMarkerProviderBase.java#L19

It is important to get UClass from incoming identifier and not identifier from incoming UClass.

Alexander Shustanov

Created August 22, 2019 12:45

Thank you! I used `getUParentForIdentifier` and now it works.

By the way, as I understand, we can have several UClass instances at the same time for the same class?

My now code look like:

override fun doCollectSlowLineMarkers(elements: MutableList<PsiElement>, result: MutableCollection<LineMarkerInfo<PsiElement>>) {
    elements.asSequence()
            .map { getUParentForIdentifier(it) }
            .distinct()
            .forEach { uElement ->
                when (uElement) {
                    is UClass -> {
                        collectMarkersForClass(uElement, result)
                    }
                }
            }
}

Previously it was:

elements.asSequence()
        .map(PsiElement::toUElement)
        .distinct()
        .forEach { uElement ->
            when (uElement) {
                is UClass -> {
                    collectMarkersForClass(uElement, result)
                }
            }
        }

So, there are different UClass instances?

Nicolay Mitropolsky

Created August 26, 2019 14:35

> By the way, as I understand, we can have several UClass instances at the same time for the same class?

Do you mean caching? No UClasses are not cached so you'll create a new UClass instance each time you'll convert element to Uast.

Ans anyway I don't see any reason to use `distinct` here (at least in upper case), please report if you still need it for some reason

Please sign in to leave a comment.