enumerate the branches of a sealed class up to 2 levels

EnumerateSealed.kt

import kotlin.reflect.KClass

sealed class States {
    sealed class StateA : States() {
        object One : StateA()
        object Two : StateA()
    }

    sealed class StateB : States() {
        object Three : StateB()
        object Four : StateB()
        sealed class Animals : StateB() {
            object Cat: Animals()
            object Dog: Animals()
        }
    }
}


fun main() {
    States::class.prettyPrintSealedClass()

    States::class.branches().forEach {
        println(it)
    }
}

fun KClass<*>.prettyPrintSealedClass(recursionLevel: Int = 1) {
    if (this.isSealed) {
        this.sealedSubclasses.forEach {
            println("${createPluses(recursionLevel)} ${it.simpleName}")
            if (it.isSealed) {
                it.prettyPrintSealedClass(recursionLevel + 1)
            }
        }
    }
}

fun <T: KClass<*>> T.branches():Collection<KClass<*>> {
    return this.sealedSubclasses.flatMap {
        if (it.isSealed) {
            it.branches()
        } else {
            listOf(it)
        }
    }
}



fun createPluses(recursionLevel: Int): String {
    val stringBuilder = StringBuilder()
    for (i in 0 until recursionLevel) {
        stringBuilder.append(" +")
    }
    return stringBuilder.toString()
}


/*
output:
----------------------
States
 + StateA
 + + One
 + + Two
 + StateB
 + + Three
 + + Four
 + + Animals
 + + + Cat
 + + + Dog
 */