SetBackedMap

gistfile1.txt

class SetBackedMap<K, V>(private val set: Set<Map.Entry<K, V>>) : Map<K, V> {

    override val entries: Set<Map.Entry<K, V>> = set
    override val keys: Set<K> = set.map { (key, _) -> key }.toSet()
    override val size: Int = set.size
    override val values: Collection<V> = set.map { (_, value) -> value }

    override fun containsKey(key: K): Boolean {
        return set.any { (possibleKey, _) -> possibleKey == key }
    }

    override fun containsValue(value: V): Boolean {
        return set.any { (_, possibleValue) -> possibleValue == value }
    }

    override fun get(key: K): V? {
        return set.find { (possibleKey, _) -> possibleKey == key }?.value
    }

    override fun isEmpty(): Boolean {
        return set.isEmpty()
    }

}