structure BraceDfa =
struct
  val dead = 0
  val start = 1
  val final = 2

  fun makeStart i =
    let
      val chr = Char.chr i
    in
      if chr = #"{" orelse chr = #"}" orelse chr = #"[" orelse chr = #"]" then
        final
      else
        dead
    end

  val deadTable = SpaceDfa.deadTable
  val startTable = Vector.tabulate (255, makeStart)
  val finalTable = deadTable

  val tables = #[deadTable, startTable, finalTable]

  fun isFinal state = state = final

  fun next (state, chr) =
    let
      val table = Vector.sub (tables, state)
      val idx = Char.ord chr
    in
      Vector.sub (table, idx)
    end
end