KotlinClassMetadata

Represents the parsed metadata of a Kotlin JVM class file. Entry point for parsing metadata on JVM.

To create an instance of KotlinClassMetadata, first obtain an instance of Metadata annotation on a class file, and then call KotlinClassMetadata.read. Metadata annotation can be obtained either via reflection or created from data from a binary class file, using its constructor or helper function kotlinx.metadata.jvm.Metadata.

KotlinClassMetadata itself does not have any meaningful methods or properties; to work with it, it is required to do a when over subclasses. Different subclasses of KotlinClassMetadata represent different kinds of class files produced by Kotlin compiler. It is recommended to study documentation for each subclass and decide what subclasses one has to handle in the when expression, trying to cover as much as possible. Normally, one would need at least a Class and a FileFacade, as these are two most common kinds.

Most of the subclasses declare a property to view metadata as a Km data structure — for example, KotlinClassMetadata.Class.kmClass. Some of them also can contain additional properties, e.g. KotlinClassMetadata.MultiFileClassPart.facadeClassName. Km data structures represent Kotlin declarations and offer a variety of properties to introspect and alter them. After desired changes are made, it is possible to get a new raw metadata instance with a corresponding write function, such as KotlinClassMetadata.writeClass.

Here is an example of reading a content name of some metadata:

fun displayName(metadata: Metadata): String = when (val kcm = KotlinClassMetadata.read(metadata)) {
    is KotlinClassMetadata.Class -> "Class ${kcm.kmClass.name}"
    is KotlinClassMetadata.FileFacade -> "File facade with functions: ${kcm.kmPackage.functions.joinToString { it.name }}"
    is KotlinClassMetadata.SyntheticClass -> kcm.kmLambda?.function?.name?.let { "Lambda $it" } ?: "Synthetic class"
    is KotlinClassMetadata.MultiFileClassFacade -> "Multifile class facade with parts: ${kcm.partClassNames.joinToString()}"
    is KotlinClassMetadata.MultiFileClassPart -> "Multifile class part ${kcm.facadeClassName}"
    is KotlinClassMetadata.Unknown -> "Unknown metadata"
}

Inheritors