A Stack-based Processing Context for Kotlin

StackBasedContext.kt

class StackBasedContext(
    val nestingStack: Deque<NestingLevel> = ArrayDeque(),
    val problems: MutableList<Pair<String, List<NestingLevel>>> = mutableListOf(),
) {
    override fun toString() = nestingStack.ifEmpty { listOf("(root)") }.joinToString("/")

    fun addProblem(msg: String) { problems.add(msg to nestingStack.descendingIterator().asSequence().toList()) }

    fun pushLevel(dataParam: KParameter): PopOnClose { nestingStack.push(NestingLevel(dataParam)); return PopOnClose() }
    fun pushLevel(collectionIndex: Int): PopOnClose { nestingStack.push(NestingLevel(collectionIndex = collectionIndex)); return PopOnClose() }
    fun popLevel(): NestingLevel = nestingStack.pop()

    data class NestingLevel(
        // ... Whatever your processing context needs on each level.
    ) {
        override fun toString() = ...
    }

    /** Allows to leverage use { } with MapperContext. */
    inner class PopOnClose : AutoCloseable {
        override fun close() { this@StackBasedContext.nestingStack.pop() }
    }
}