structure AllDfa =
struct
  type t =
    { curInt: int
    , curSpace: int
    , curBrace: int
    , lastInt: int
    , lastSpace: int
    , lastBrace: int
    }

  val initial: t =
    { curInt = IntDfa.start
    , curSpace = SpaceDfa.start
    , curBrace = BraceDfa.start
    , lastInt = ~1
    , lastSpace = ~1
    , lastBrace = ~1
    }

  fun areAllDead ({curInt, curSpace, curBrace, ...}: t) =
    curInt = 0 andalso curSpace = 0 andalso curBrace = 0

  fun update (chr, dfa, pos) =
    let
      val {curInt, curSpace, curBrace, lastInt, lastBrace, lastSpace} = dfa

      val curInt = IntDfa.next (curInt, chr)
      val curSpace = SpaceDfa.next (curSpace, chr)
      val curBrace = BraceDfa.next (curBrace, chr)

      val lastInt = if IntDfa.isFinal curInt then pos else lastInt
      val lastSpace = if SpaceDfa.isFinal curSpace then pos else lastSpace
      val lastBrace = if BraceDfa.isFinal curBrace then pos else lastBrace
    in
      { curInt = curInt
      , curSpace = curSpace
      , curBrace = curBrace
      , lastInt = lastInt
      , lastBrace = lastBrace
      , lastSpace = lastSpace
      }
    end
end