Iteratable Enum

enum.swift

protocol Iteratable {}
extension RawRepresentable where Self: RawRepresentable {
	static func iterateEnum<T: Hashable>(_: T.Type) -> AnyIterator<T> {
		var i = 0
		return AnyIterator {
			let next = withUnsafePointer(to: &i) {
				$0.withMemoryRebound(to: T.self, capacity: 1) { $0.pointee }
			}
			if next.hashValue != i { return nil }
			i += 1
			return next
		}
	}
}

extension Iteratable where Self: RawRepresentable, Self: Hashable {
	static func hashValues() -> AnyIterator<Self> {
		return iterateEnum(self)
	}

	static func rawValues() -> [Self.RawValue] {
		return hashValues().map({$0.rawValue})
	}
}

enum Direction: String, Iteratable {
	case north, south, east, west
}

Direction.rawValues() //["north", "south", "east", "west"]