EnumCollection Swift 3.1+

EnumCollection.swift

protocol EnumCollection {}
extension EnumCollection where Self: Hashable {
	static func sequence() -> AnySequence<Self> {
		return AnySequence { () -> AnyIterator<Self> in
			var raw = 0
			return AnyIterator {
				let `case` : Self = withUnsafePointer(to: &raw) { $0.withMemoryRebound(to: Self.self, capacity: 1) { $0.pointee } }
				guard `case`.hashValue == raw else { return nil }
				raw += 1
				return `case`
			}
		}
	}

}
extension EnumCollection where Self: Hashable, Self: RawRepresentable {
	static func sequence() -> AnySequence<(Self,Self.RawValue)> {
		return AnySequence { () -> AnyIterator<(Self, Self.RawValue)> in
			var raw = 0
			return AnyIterator {
				let `case` : Self = withUnsafePointer(to: &raw) { $0.withMemoryRebound(to: Self.self, capacity: 1) { $0.pointee } }
				let value = `case`.rawValue
				guard `case`.hashValue == raw else { return nil }
				raw += 1
				return (`case`, value)
			}
		}
	}

}