Add a PsiElement without adding text to the PsiFile Follow

Answered

Created July 14, 2021 14:32

I'm trying to add a method (PsiMethod) to a class (PsiClass) so that IDEA shows this method when typing. I did this, but I ran into a problem: when I add PsiMethod to PsiClass, the text of this method appears in the file, and I don't need it. I need to add a method so that it is highlighted by IDEA, but it is not displayed in the file as text.

How can this be done?

Here is my code how I add PsiMethod to PsiClass:

val module = ModuleManager.getInstance(project).modules.first()
val file = FilenameIndex
        .getFilesByName(
            project, 
            "TestPsiFile.java",
            module.moduleContentScope)
        .first()
val newMethod = PsiElementFactory.getInstance(project).createMethod("testMethod", PsiType.VOID)

WriteCommandAction.runWriteCommandAction(project) {
        file.children
            .filter { it.elementType == JavaElementType.CLASS }
            .map { it.add(newMethod) }
}

3 comments

Yann Cebron

Created July 15, 2021 07:51

Use com.intellij.psi.augment.PsiAugmentProvider extension to add "fake" elements in Java

Lojka10

Created July 15, 2021 13:19

Use com.intellij.psi.augment.PsiAugmentProvider extension to add "fake" elements in Java

Thanks for the answer, but could you tell me how to use PsiAugmentProvider?

I tried to figure it out, but I ran into a problem.

Here's what I did:

Created theTestPsiAugmentProvider class and inherited it from PsiAugmentProvider.

class TestPsiAugmentProvider : PsiAugmentProvider() {
    override fun <Psi : PsiElement?> getAugments(
        element: PsiElement,
        type: Class<Psi>,
        nameHint: String?
    ): MutableList<Psi> {
        if (element.containingFile.name == "TestPsiFile.java" && element.elementType == JavaElementType.CLASS && type.name == "com.intellij.psi.PsiClass") {
            val method = LightMethodBuilder(element.manager, JavaLanguage.INSTANCE, "testMethod").apply {
                containingClass = element as PsiClass
                setMethodReturnType(PsiType.VOID)
                setModifiers("public")
            }

            return mutableListOf(method as Psi) //So far, I'm only returning a new method for the test
        }

        return super.getAugments(element, type, nameHint)
    }
}

Added TestPsiAugmentProvider to plugin.xml.

<extensions defaultExtensionNs="com.intellij">
    <lang.psiAugmentProvider implementation="TestPsiAugmentProvider"/>
</extensions>

When I test the plugin, IDEA does not highlight the testMethod method in red, but it also does not suggest this method when I type. What could be the problem?

Yann Cebron

Created July 19, 2021 15:49

Completion should be supported. see com.intellij.java.codeInsight.completion.NormalCompletionTest#"test member as Java keyword"

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