module CacheSim.IntMap exposing (..)

type alias IntMap a = List a

intMapGet : Int -> IntMap a -> Maybe a
intMapGet i m =
    case (i, m) of
        (_, []) -> Nothing
        (0, (x::xs)) -> Just x
        (n, (x::xs)) -> intMapGet (n-1) xs

intMapDelete : Int -> IntMap a -> IntMap a
intMapDelete i m =
    case (i, m) of
        (_, []) -> []
        (0, x::xs) -> xs
        (n, x::xs) -> x :: intMapDelete (n-1) xs

intMapUpdate : Int -> (a -> a) -> IntMap a -> IntMap a
intMapUpdate i f m =
    case (i, m) of
        (_, []) -> []
        (0, (x::xs)) -> (f x)::xs
        (n, (x::xs)) -> x :: intMapUpdate (n-1) f xs

intMapPut : Int -> a -> IntMap a -> IntMap a
intMapPut i v = intMapUpdate i (\_ -> v)

intMapFind : (a -> Bool) -> IntMap a -> Maybe Int
intMapFind f m =
    let
        findHelper n l =
            case l of
                [] -> Nothing
                (x::xs) -> if f x then Just n else findHelper (n + 1) xs
    in
        findHelper 0 m