Enum with associated values and default values/raw values?

Using Swift
,
1

I am trying to build a JSON parser as an exercise and I was thinking what if I have an enum called Token with values like

enum Token: String {
    case OpenCurly = "{"
    case CloseCurly = "}"
    case OpenArray = "["
    case CloseArray = "]"
    case Comma = ","
    case Colon = ":"
    case String(String)
    case Number
    case Boolean
    case Null
}

here OpenCurly can only be "{" but a string can be anything. But I guess I cannot have associated values and raw values together? If there a way for an associated value to be a certain string or am going about this the wrong way?

1 Like
2

When setting the raw type like that the compiler will automatically synthesize the RawRepresentable conformance. When used this way, it can't derive a raw value when an associated value is present. You will have to make your own RawRepresentable comformance:

enum Token: RawRepresentable {
    
    case OpenCurly
    case CloseCurly
    case OpenArray
    case CloseArray
    case Comma
    case Colon
    case String(String)
    case Number
    case Boolean
    case Null
    
    init?(rawValue: String) {
        switch rawValue {
        case "{":
            self = .OpenCurly
        // other values
        default:
            self = .String(rawValue)
        }
    }
    
    var rawValue: String {
        switch self {
        case .OpenCurly:
            "{"
        case .String(let value):
            value
        // other values
        }
    }
}
3 Likes
3

ah got it. I think will not use raw values here but only use associated data for some cases where it makes sense.

Thank you!