MvRxMapExtensions.kt

/**
 * Returns a new immutable map with the provided keys set/updated.
 */
fun <K, V> Map<K, V>.copy(vararg pairs: Pair<K, V>) = HashMap<K, V>(size + pairs.size).apply {
    putAll(this@copy)
    pairs.forEach { put(it.first, it.second) }
}

/**
 * Returns a new map with the provided keys removed.
 */
fun <K, V> Map<K, V>.delete(vararg keys: K): Map<K, V> {
    // This should be slightly more efficient than Map.filterKeys because we start with a map of the
    // correct size rather than a growing LinkedHashMap.
    return HashMap<K, V>(size - keys.size).apply {
        this@delete.entries.asSequence()
                .filter { it.key !in keys }
                .forEach { put(it.key, it.value) }
    }
}