Enum.kt

inline fun <reified T : Enum<T>> requireEnumBy(
    fallback: EnumSet<T>.() -> T = EnumSet<T>::defFallback,
    predicate: (T) -> Boolean
): T = requireEnumBy(T::class.java, fallback, predicate)

inline fun <reified T : Enum<T>> findEnumBy(
    predicate: (T) -> Boolean
): T? = with(EnumSet.allOf(T::class.java)) { find(predicate) }

inline fun <T : Enum<T>> requireEnumBy(
    enumCls: Class<T>,
    fallback: EnumSet<T>.() -> T = { defFallback(enumCls) },
    predicate: (T) -> Boolean
): T = with(EnumSet.allOf(enumCls)) { find(predicate) ?: fallback() }

inline fun <reified T : Enum<T>> find(predicate: (T) -> Boolean): T? = EnumSet.allOf(T::class.java).find(predicate)

inline fun <reified T : Enum<T>> EnumSet<T>.defFallback(): T = defFallback(T::class.java)

fun <T : Enum<T>> EnumSet<T>.defFallback(enumCls: Class<T>): T = firstOrNull()
    ?: throw IllegalStateException("In the enum ${enumCls.simpleName} there should be at least one enumeration")