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let ( $$ ) x f = f x

let unSome = function
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    None -> assert false
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  | Some x -> x

let o2s o f =
  match o with
  | None ->
      ""
  | Some x ->
      f x

let single = function
  | [ x ] ->
      x
  | _ ->
      assert false

let rec mapd f = function
  | [] ->
      []
  | x :: xs ->
      let y1, y2 = f x in
      y1 :: y2 :: mapd f xs

let tabulate n f =
  let a = Array.init n f in
  Array.get a

let tabulateb n f =
  let a = Array.init n f in
  Array.get a,
  Array.fold_left (fun count element ->
    if element then count + 1 else count
  ) 0 a

let tabulatef number fold n dummy f =
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  let a = Array.make n dummy in
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  let () = fold (fun () element ->
    a.(number element) <- f element
  ) () in
  let get element =
    a.(number element)
  in
  get

let tabulateo number fold n f =
  let c = ref 0 in
  let get =
    tabulatef number fold n None (fun element ->
      let image = f element in
      begin match image with
      | Some _ ->
	  incr c
      | None ->
	  ()
      end;
      image
    )
  in
  get, !c

module IntSet = Set.Make (struct 
			    type t = int
			    let compare = ( - )
			  end)

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type 'a iter = ('a -> unit) -> unit

let separated_iter_to_string printer separator iter = 
  let b = Buffer.create 32 in
  let first = ref true in
  iter (fun x ->
    if !first then begin
      Buffer.add_string b (printer x);
      first := false
    end
    else begin
      Buffer.add_string b separator;
      Buffer.add_string b (printer x)
    end
  );
  Buffer.contents b

let separated_list_to_string printer separator xs = 
  separated_iter_to_string printer separator (fun f -> List.iter f xs)

let terminated_iter_to_string printer terminator iter =
  let b = Buffer.create 32 in
  iter (fun x ->
    Buffer.add_string b (printer x);
    Buffer.add_string b terminator
  );
  Buffer.contents b

let terminated_list_to_string printer terminator xs =
  terminated_iter_to_string printer terminator (fun f -> List.iter f xs)
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let index_map string_map = 
  let n = StringMap.cardinal string_map in
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  let a = Array.make n None in
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  let conv, _ = StringMap.fold 
    (fun k v (conv, idx) ->
       a.(idx) <- Some (k, v);
       StringMap.add k idx conv, idx + 1)
    string_map (StringMap.empty, 0) 
  in
    ((fun n -> snd (unSome a.(n))),
     (fun k -> StringMap.find k conv),
     (fun n -> fst (unSome a.(n))))
  
let support_assoc l x =
  try
    List.assoc x l
  with Not_found -> x

let index (strings : string list) : int * string array * int StringMap.t =
  let name = Array.of_list strings
  and n, map = List.fold_left (fun (n, map) s ->
    n+1, StringMap.add s n map
  ) (0, StringMap.empty) strings in
  n, name, map

(* Turning an implicit list, stored using pointers through a hash
   table, into an explicit list. The head of the implicit list is
   not included in the explicit list. *)

let materialize (table : ('a, 'a option) Hashtbl.t) (x : 'a) : 'a list =
  let rec loop x =
    match Hashtbl.find table x with
    | None ->
	[]
    | Some x ->
	x :: loop x
  in
  loop x

(* [iteri] implements a [for] loop over integers, from 0 to
   [n-1]. *)

let iteri n f =
  for i = 0 to n - 1 do
    f i
  done

(* [foldi] implements a [for] loop over integers, from 0 to [n-1],
   with an accumulator. [foldij] implements a [for] loop over
   integers, from [start] to [n-1], with an accumulator. *)

let foldij start n f accu =
  let rec loop i accu =
    if i = n then
      accu
    else
      loop (i+1) (f i accu)
  in
  loop start accu

let foldi n f accu =
  foldij 0 n f accu

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(* [mapij start n f] produces the list [ f start; ... f (n-1) ]. *)
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let mapij start n f =
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  List.rev (
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    foldij start n (fun i accu ->
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      f i :: accu
    ) []
  )

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(* [mapi n f] produces the list [ f 0; ... f (n-1) ]. *)

let mapi n f =
  mapij 0 n f

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(* [qfold f accu q] repeatedly takes an element [x] off the queue [q]
   and applies [f] to the accumulator and to [x], until [q] becomes
   empty. Of course, [f] can add elements to [q] as a side-effect.

   We allocate an option to ensure that [qfold] is tail-recursive. *)

let rec qfold f accu q =
  match
    try
      Some (Queue.take q)
    with Queue.Empty ->
      None
  with
  | Some x ->
      qfold f (f accu x) q
  | None ->
      accu

(* [qiter f q] repeatedly takes an element [x] off the queue [q] and
   applies [f] to [x], until [q] becomes empty. Of course, [f] can add
   elements to [q] as a side-effect. *)

let qiter f q =
  try
    while true do
      f (Queue.take q)
    done
  with Queue.Empty ->
    ()

let rec smap f = function
  | [] ->
      []
  | (x :: xs) as l ->
      let x' = f x
      and xs' = smap f xs in
      if x == x' && xs == xs' then
	l
      else
	x' :: xs'

let rec smapa f accu = function
  | [] ->
      accu, []
  | (x :: xs) as l ->
      let accu, x' = f accu x in
      let accu, xs' = smapa f accu xs in
      accu,
      if x == x' && xs == xs' then
	l
      else
	x' :: xs'

let normalize s =
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  let s = Bytes.of_string s in
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  let n = Bytes.length s in
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  for i = 0 to n - 1 do
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    match Bytes.get s i with
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    | '('
    | ')'
    | ',' ->
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	Bytes.set s i '_'
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    | _ ->
	()
  done;
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  Bytes.unsafe_to_string s
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(* [postincrement r] increments [r] and returns its original value. *)

let postincrement r =
  let x = !r in
  r := x + 1;
  x

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(* [map_opt f l] returns the list of [y]s such that [f x = Some y] where [x]
   is in [l], preserving the order of elements of [l]. *) 
let map_opt f l =
  List.(rev (fold_left (fun ys x ->
    match f x with
      | None -> ys
      | Some y -> y :: ys
  ) [] l))
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let new_intern capacity =
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  (* Set up a a hash table, mapping strings to unique integers. *)
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  let module H = Hashtbl.Make(struct
    type t = string
    let equal = (=)
    let hash = Hashtbl.hash
  end) in
  let table = H.create capacity in
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  (* This counts the calls to [intern]. *)
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  let c = ref 0 in
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  (* A string is mapped to a unique string, as follows. *)
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  let intern s =
    c := !c + 1;
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    try
      H.find table s
    with Not_found ->
      H.add table s s;
      s
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  and verbose () =
    Printf.fprintf stderr
      "%d calls to intern; %d unique strings.\n%!"
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      !c (H.length table)
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  in
  intern, verbose
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let new_encode_decode capacity =
  (* Set up a a hash table, mapping strings to unique integers. *)
  let module H = Hashtbl.Make(struct
    type t = string
    let equal = (=)
    let hash = Hashtbl.hash
  end) in
  let table = H.create capacity in
  (* Set up a resizable array, mapping integers to strings. *)
  let text = MenhirLib.InfiniteArray.make "" in
  (* This counts the calls to [encode]. *)
  let c = ref 0 in
  (* A string is mapped to a unique integer, as follows. *)
  let encode (s : string) : int =
    c := !c + 1;
    try
      H.find table s
    with Not_found ->
      (* The number of elements in the hash table is the next available
         unique integer code. *)
      let i = H.length table in
      H.add table s i;
      MenhirLib.InfiniteArray.set text i s;
      i
  (* An integer code can be mapped back to a string, as follows. *)
  and decode (i : int) : string =
    MenhirLib.InfiniteArray.get text i
  and verbose () =
    Printf.fprintf stderr
      "%d calls to intern; %d unique strings.\n%!"
      !c (H.length table)
  in
  encode, decode, verbose