parse.elm

-- My goal here is to be able to parse a string like "678767".
-- However, this same parser needs to be able to handle a string like "18.1.2.4"

-- My strategy is this: I parse the input as an integer.
-- If the parser has reached the end of the string, tag the chomped value as XXXXXX (see Index type below)
-- If the parser instead reaches a `.`, continue and recursively capture every integer following a `.`
-- Tag the resulting Int and List Int with XX. (see Index type below)

-- Also, I'm not sure, but I think line 16 needs this type:
-- dotDigit : List String -> Parser.Parser (Step (List Int) (List Int))

type Index
    = XXXXXX (Parser.Parser Int)
    | XX (Parser.Parser ( Int, List Int ))
    | Unknown String

dotDigit : List String -> Parser.Parser (Step (List String) (List String))
dotDigit nums =
    let
        checkNum numsSoFar num =
            if String.length num > 0 then
                Loop (num :: numsSoFar)

            else
                Done (List.reverse numsSoFar)
    in
    succeed (checkNum nums)
        |. symbol "."
        |= (getChompedString <| chompWhile Char.isDigit)


parseIndex =
    succeed identity
        |= Parser.int
        |. Parser.oneOf
            [ succeed XXXXXX
                |. Parser.end
            , succeed XX
                |. Parser.andThen
                    (\value ->
                        if value >= 1 && value <= 64 then
                            Parser.loop [] dotDigit
                                |> Parser.map (\digits -> ( value, digits ))

                        else
                            Parser.problem "out of range"
                    )
            ]