NFA.State.fs

module NFA =

    [<CustomEquality>]
    [<CustomComparison>]
    type State<'T> =
        | Match
        | Branch of Pair<'T>
        | Read of int * ('T -> bool) * State<'T>

        member this.Key =
            match this with
            | Match -> 0
            | Branch x -> x.k
            | Read (i, _, _) -> i

        override this.Equals other =
            match other with
            | :? State<'T> as o ->
                this.Key = o.Key
            | _ ->
                false

        override this.GetHashCode() =
            this.Key

        interface IComparable with
            member this.CompareTo other =
                compare (hash other) this.Key

    and Pair<'T> =
        {
            mutable k : int
            mutable x : State<'T>
            y : State<'T>
        }