Annotations

KaAnnotated

KaAnnotated is an interface exposing a list of annotations. All types and almost all symbols implement it.

The only property KaAnnotated declares is annotations of the KaAnnotationList type. KaAnnotationList itself is implements a List<KaAnnotation>, so you can directly iterate over annotations:

fun KaSession.processAnnotations(symbol: KaDeclarationSymbol) {
    for (anno in symbol.annotations) {
        // Process the 'annotation'
    }
}

KaAnnotationsList is not just a list. It can also efficiently check whether an annotation with some ClassId is there:

fun KaSession.hasDeprecatedAnnotation(symbol: KaDeclarationSymbol) {
    val classId = ClassId.fromString("kotlin/Deprecated")
    return classId in symbol.annotations
}

You can also get a list of annotations with a specific ClassId. Kotlin allows repeatable annotations, so a list of them is returned:

fun KaSession.findDeprecatedAnnotation(symbol: KaDeclarationSymbol): KaAnnotation? {
    val classId = ClassId.fromString("kotlin/Deprecated")
    return symbol.annotations[classId].firstOrNull()
}

Finally, KaAnnotationList exposes a collection of all annotation ClassIds:

fun KaSession.collectAnnotations(types: List<KaType>): Set<ClassId> {
    return types.flatMapTo(HashSet()) { it.annotations.classIds }
}

Use-Site Targets

Annotations on declarations can have use-site targets, specifying where the annotation applies (e.g., property, field, or parameter). You can use the useSiteTarget property of KtAnnotation to access this information.