NonNullableMutableMap

NonNullableMutableMap.kt

interface NonNullableMutableMap<K,V> : MutableMap<K,V> {
	override fun get(key: K): V
	operator fun set(key: K, value: V) = put(key, value)
}

fun <K,V> MutableMap<K,V>.withoutNullValues(default: () -> V): NonNullableMutableMap<K, V> {
	if (this is NonNullableMutableMap) return this
	return NonNullableMapWrapper(this, default)
}

class NonNullableMapWrapper<K,V>(val map: MutableMap<K,V>, val default: () -> V) : NonNullableMutableMap<K,V>, MutableMap<K,V> by map {
	override fun get(key: K): V = map.getOrPut(key, default)
}