Swift enum parsing using the swift-parsing library

RawRepresentable+Parsing.swift

extension RawRepresentable where Self.RawValue == String {
    /// Parses out the first matching raw value from a list of possible values, or returns nil.
    ///
    /// Example:
    ///
    ///     enum SomeValues: String, CaseIterable {
    ///         case one
    ///         case two
    ///     }
    ///
    ///     SomeValues.firstMatchingValue(in: [.one]).parse("one").output // SomeValues.one
    ///     SomeValues.firstMatchingValue(in: [.two]).parse("one").output // nil
    ///
    static func firstMatchingValue(in possibleValues: [Self]) -> AnyParser<Substring, Self> {
        OneOfMany(
            possibleValues.map { value in
                StartsWith(value.rawValue[...]).map { value }
            }
        )
        .eraseToAnyParser()
    }
}

extension RawRepresentable where Self: CaseIterable, Self.RawValue == String {
    /// Parses out the first matching raw value from all possible cases, or returns nil.
    ///
    /// Example:
    ///
    ///     enum SomeValues: String, CaseIterable {
    ///         case one
    ///         case two
    ///     }
    ///
    ///     SomeValues.firstMatchingValue.parse("one").output // SomeValues.one
    ///     SomeValues.firstMatchingValue.parse("six").output // nil
    ///
    static var firstMatchingValue: AnyParser<Substring, Self> {
        firstMatchingValue(in: allCases as? [Self] ?? [])
    }
}