1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
(************************************************************************)
(*         *   The Coq Proof Assistant / The Coq Development Team       *)
(*  v      *   INRIA, CNRS and contributors - Copyright 1999-2019       *)
(* <O___,, *       (see CREDITS file for the list of authors)           *)
(*   \VV/  **************************************************************)
(*    //   *    This file is distributed under the terms of the         *)
(*         *     GNU Lesser General Public License Version 2.1          *)
(*         *     (see LICENSE file for the text of the license)         *)
(************************************************************************)

open Util
open CErrors
open Names
open Libnames
open Constrexpr
open Extend
open Notation_gram
open Pcoq

(**********************************************************************)
(* This determines (depending on the associativity of the current
   level and on the expected associativity) if a reference to constr_n is
   a reference to the current level (to be translated into "SELF" on the
   left border and into "constr LEVEL n" elsewhere), to the level below
   (to be translated into "NEXT") or to an below wrt associativity (to be
   translated in camlp5 into "constr" without level) or to another level
   (to be translated into "constr LEVEL n")

   The boolean is true if the entry was existing _and_ empty; this to
   circumvent a weakness of camlp5 whose undo mechanism is not the
   converse of the extension mechanism *)

let constr_level = string_of_int

let default_levels =
  [200,Gramlib.Gramext.RightA,false;
   100,Gramlib.Gramext.RightA,false;
   99,Gramlib.Gramext.RightA,true;
   90,Gramlib.Gramext.RightA,true;
   10,Gramlib.Gramext.LeftA,false;
   9,Gramlib.Gramext.RightA,false;
   8,Gramlib.Gramext.RightA,true;
   1,Gramlib.Gramext.LeftA,false;
   0,Gramlib.Gramext.RightA,false]

let default_pattern_levels =
  [200,Gramlib.Gramext.RightA,true;
   100,Gramlib.Gramext.RightA,false;
   99,Gramlib.Gramext.RightA,true;
   90,Gramlib.Gramext.RightA,true;
   10,Gramlib.Gramext.LeftA,false;
   1,Gramlib.Gramext.LeftA,false;
   0,Gramlib.Gramext.RightA,false]

let default_constr_levels = (default_levels, default_pattern_levels)

let find_levels levels = function
  | InConstrEntry -> levels, String.Map.find "constr" levels
  | InCustomEntry s ->
     try levels, String.Map.find s levels
     with Not_found ->
     String.Map.add s ([],[]) levels, ([],[])

let save_levels levels custom lev =
  let s = match custom with InConstrEntry -> "constr" | InCustomEntry s -> s in
  String.Map.add s lev levels

(* At a same level, LeftA takes precedence over RightA and NoneA *)
(* In case, several associativity exists for a level, we make two levels, *)
(* first LeftA, then RightA and NoneA together *)

let admissible_assoc = function
  | Gramlib.Gramext.LeftA, Some (Gramlib.Gramext.RightA | Gramlib.Gramext.NonA) -> false
  | Gramlib.Gramext.RightA, Some Gramlib.Gramext.LeftA -> false
  | _ -> true

let create_assoc = function
  | None -> Gramlib.Gramext.RightA
  | Some a -> a

let error_level_assoc p current expected =
  let open Pp in
  let pr_assoc = function
    | Gramlib.Gramext.LeftA -> str "left"
    | Gramlib.Gramext.RightA -> str "right"
    | Gramlib.Gramext.NonA -> str "non" in
  user_err 
    (str "Level " ++ int p ++ str " is already declared " ++
     pr_assoc current ++ str " associative while it is now expected to be " ++
     pr_assoc expected ++ str " associative.")

let create_pos = function
  | None -> Gramlib.Gramext.First
  | Some lev -> Gramlib.Gramext.After (constr_level lev)

let find_position_gen current ensure assoc lev =
  match lev with
  | None ->
      current, (None, None, None, None)
  | Some n ->
      let after = ref None in
      let init = ref None in
      let rec add_level q = function
        | (p,_,_ as pa)::l when p > n -> pa :: add_level (Some p) l
        | (p,a,reinit)::l when Int.equal p n ->
            if reinit then
              let a' = create_assoc assoc in
              (init := Some (a',create_pos q); (p,a',false)::l)
            else if admissible_assoc (a,assoc) then
              raise Exit
            else
              error_level_assoc p a (Option.get assoc)
        | l -> after := q; (n,create_assoc assoc,ensure)::l
      in
      try
        let updated = add_level None current in
        let assoc = create_assoc assoc in
        begin match !init with
        | None ->
          (* Create the entry *)
           updated, (Some (create_pos !after), Some assoc, Some (constr_level n), None)
        | _ ->
          (* The reinit flag has been updated *)
           updated, (Some (Gramlib.Gramext.Level (constr_level n)), None, None, !init)
        end
      with
          (* Nothing has changed *)
          Exit ->
            (* Just inherit the existing associativity and name (None) *)
            current, (Some (Gramlib.Gramext.Level (constr_level n)), None, None, None)

let rec list_mem_assoc_triple x = function
  | [] -> false
  | (a,b,c) :: l -> Int.equal a x || list_mem_assoc_triple x l

let register_empty_levels accu forpat levels =
  let rec filter accu = function
  | [] -> ([], accu)
  | (where,n) :: rem ->
    let rem, accu = filter accu rem in
    let accu, (clev, plev) = find_levels accu where in
    let levels = if forpat then plev else clev in
    if not (list_mem_assoc_triple n levels) then
      let nlev, ans = find_position_gen levels true None (Some n) in
      let nlev = if forpat then (clev, nlev) else (nlev, plev) in
      (where, ans) :: rem, save_levels accu where nlev
    else rem, accu
  in
  let (l,accu) = filter accu levels in
  List.rev l, accu

let find_position accu custom forpat assoc level =
  let accu, (clev, plev) = find_levels accu custom in
  let levels = if forpat then plev else clev in
  let nlev, ans = find_position_gen levels false assoc level in
  let nlev = if forpat then (clev, nlev) else (nlev, plev) in
  (ans, save_levels accu custom nlev)

(**************************************************************************)
(*
 * --- Note on the mapping of grammar productions to camlp5 actions ---
 *
 * Translation of environments: a production
 *   [ nt1(x1) ... nti(xi) ] -> act(x1..xi)
 * is written (with camlp5 conventions):
 *   (fun vi -> .... (fun v1 -> act(v1 .. vi) )..)
 * where v1..vi are the values generated by non-terminals nt1..nti.
 * Since the actions are executed by substituting an environment,
 * the make_*_action family build the following closure:
 *
 *      ((fun env ->
 *          (fun vi ->
 *             (fun env -> ...
 *
 *                  (fun v1 ->
 *                     (fun env -> gram_action .. env act)
 *                     ((x1,v1)::env))
 *                  ...)
 *             ((xi,vi)::env)))
 *         [])
 *)

(**********************************************************************)
(** Declare Notations grammar rules                                   *)

(**********************************************************************)
(* Binding constr entry keys to entries                               *)

(* Camlp5 levels do not treat NonA: use RightA with a NEXT on the left *)
let camlp5_assoc =
  let open Gramlib.Gramext in function
    | Some NonA | Some RightA -> RightA
    | None | Some LeftA -> LeftA

let assoc_eq al ar =
  let open Gramlib.Gramext in
  match al, ar with
  | NonA, NonA
  | RightA, RightA
  | LeftA, LeftA -> true
  | _, _ -> false

(* [adjust_level assoc from prod] where [assoc] and [from] are the name
   and associativity of the level where to add the rule; the meaning of
   the result is

     None = SELF
     Some None = NEXT
     Some (Some (n,cur)) = constr LEVEL n
         s.t. if [cur] is set then [n] is the same as the [from] level *)
let adjust_level assoc from = let open Gramlib.Gramext in function
(* Associativity is None means force the level *)
  | (NumLevel n,BorderProd (_,None)) -> Some (Some (n,true))
(* Compute production name on the right side *)
  (* If NonA or LeftA on the right-hand side, set to NEXT *)
  | (NumLevel n,BorderProd (Right,Some (NonA|LeftA))) ->
      Some None
  (* If RightA on the right-hand side, set to the explicit (current) level *)
  | (NumLevel n,BorderProd (Right,Some RightA)) ->
      Some (Some (n,true))
(* Compute production name on the left side *)
  (* If NonA on the left-hand side, adopt the current assoc ?? *)
  | (NumLevel n,BorderProd (Left,Some NonA)) -> None
  (* If the expected assoc is the current one, set to SELF *)
  | (NumLevel n,BorderProd (Left,Some a)) when assoc_eq a (camlp5_assoc assoc) ->
      None
  (* Otherwise, force the level, n or n-1, according to expected assoc *)
  | (NumLevel n,BorderProd (Left,Some a)) ->
    begin match a with
    | LeftA -> Some (Some (n, true))
    | _ -> Some None
    end
  (* None means NEXT *)
  | (NextLevel,_) -> Some None
(* Compute production name elsewhere *)
  | (NumLevel n,InternalProd) ->
    if from = n + 1 then Some None else Some (Some (n, Int.equal n from))

type _ target =
| ForConstr : constr_expr target
| ForPattern : cases_pattern_expr target

type prod_info = production_level * production_position

type (_, _) entry =
| TTName : ('self, lname) entry
| TTReference : ('self, qualid) entry
| TTBigint : ('self, string) entry
| TTConstr : notation_entry * prod_info * 'r target -> ('r, 'r) entry
| TTConstrList : prod_info * string Tok.p list * 'r target -> ('r, 'r list) entry
| TTPattern : int -> ('self, cases_pattern_expr) entry
| TTOpenBinderList : ('self, local_binder_expr list) entry
| TTClosedBinderList : string Tok.p list -> ('self, local_binder_expr list list) entry

type _ any_entry = TTAny : ('s, 'r) entry -> 's any_entry

let constr_custom_entry : (string, Constrexpr.constr_expr) entry_command =
  create_entry_command "constr" (fun s st -> [s], st)
let pattern_custom_entry : (string, Constrexpr.cases_pattern_expr) entry_command =
  create_entry_command "pattern" (fun s st -> [s], st)

let custom_entry_locality = Summary.ref ~name:"LOCAL-CUSTOM-ENTRY" String.Set.empty
(** If the entry is present then local *)

let create_custom_entry ~local s =
  if List.mem s ["constr";"pattern";"ident";"global";"binder";"bigint"] then
    user_err Pp.(quote (str s) ++ str " is a reserved entry name.");
  let sc = "constr:"^s in
  let sp = "pattern:"^s in
  let _ = extend_entry_command constr_custom_entry sc in
  let _ = extend_entry_command pattern_custom_entry sp in
  let () = if local then custom_entry_locality := String.Set.add s !custom_entry_locality in
  ()

let find_custom_entry s =
  let sc = "constr:"^s in
  let sp = "pattern:"^s in
  try (find_custom_entry constr_custom_entry sc, find_custom_entry pattern_custom_entry sp)
  with Not_found -> user_err Pp.(str "Undeclared custom entry: " ++ str s ++ str ".")

let locality_of_custom_entry s = String.Set.mem s !custom_entry_locality

(* This computes the name of the level where to add a new rule *)
let interp_constr_entry_key : type r. _ -> r target -> int -> r Entry.t * int option =
  fun custom forpat level ->
  match custom with
  | InCustomEntry s ->
     (let (entry_for_constr, entry_for_patttern) = find_custom_entry s in
     match forpat with
     | ForConstr -> entry_for_constr, Some level
     | ForPattern -> entry_for_patttern, Some level)
  | InConstrEntry ->
  match forpat with
  | ForConstr ->
    if level = 200 then Constr.binder_constr, None
    else Constr.operconstr, Some level
  | ForPattern -> Constr.pattern, Some level

let target_entry : type s. notation_entry -> s target -> s Entry.t = function
| InConstrEntry ->
   (function
   | ForConstr -> Constr.operconstr
   | ForPattern -> Constr.pattern)
| InCustomEntry s ->
   let (entry_for_constr, entry_for_patttern) = find_custom_entry s in
   function
   | ForConstr -> entry_for_constr
   | ForPattern -> entry_for_patttern

let is_self from e = match e with
| (NumLevel n, BorderProd (Right, _ (* Some(NonA|LeftA) *))) -> false
| (NumLevel n, BorderProd (Left, _)) -> Int.equal from n
| _ -> false

let is_binder_level from e = match e with
| (NumLevel 200, (BorderProd (Right, _) | InternalProd)) -> from = 200
| _ -> false

let make_sep_rules = function
  | [tk] -> Atoken tk
  | tkl ->
  let rec mkrule : 'a Tok.p list -> 'a rules = function
  | [] -> Rules (Stop, fun _ -> (* dropped anyway: *) "")
  | tkn :: rem ->
    let Rules (r, f) = mkrule rem in
    let r = NextNoRec (r, Atoken tkn) in
    Rules (r, fun _ -> f)
  in
  let r = mkrule (List.rev tkl) in
  Arules [r]

type ('s, 'a) mayrec_symbol =
| MayRecNo : ('s, norec, 'a) symbol -> ('s, 'a) mayrec_symbol
| MayRecMay : ('s, mayrec, 'a) symbol -> ('s, 'a) mayrec_symbol

let symbol_of_target : type s. _ -> _ -> _ -> _ -> s target -> (s, s) mayrec_symbol = fun custom p assoc from forpat ->
  if custom = InConstrEntry && is_binder_level from p then MayRecNo (Aentryl (target_entry InConstrEntry forpat, "200"))
  else if is_self from p then MayRecMay Aself
  else
    let g = target_entry custom forpat in
    let lev = adjust_level assoc from p in
    begin match lev with
    | None -> MayRecNo (Aentry g)
    | Some None -> MayRecMay Anext
    | Some (Some (lev, cur)) -> MayRecNo (Aentryl (g, string_of_int lev))
    end

let symbol_of_entry : type s r. _ -> _ -> (s, r) entry -> (s, r) mayrec_symbol = fun assoc from typ -> match typ with
| TTConstr (s, p, forpat) -> symbol_of_target s p assoc from forpat
| TTConstrList (typ', [], forpat) ->
  begin match symbol_of_target InConstrEntry typ' assoc from forpat with
  | MayRecNo s -> MayRecNo (Alist1 s)
  | MayRecMay s -> MayRecMay (Alist1 s) end
| TTConstrList (typ', tkl, forpat) ->
  begin match symbol_of_target InConstrEntry typ' assoc from forpat with
  | MayRecNo s -> MayRecNo (Alist1sep (s, make_sep_rules tkl))
  | MayRecMay s -> MayRecMay (Alist1sep (s, make_sep_rules tkl)) end
| TTPattern p -> MayRecNo (Aentryl (Constr.pattern, string_of_int p))
| TTClosedBinderList [] -> MayRecNo (Alist1 (Aentry Constr.binder))
| TTClosedBinderList tkl -> MayRecNo (Alist1sep (Aentry Constr.binder, make_sep_rules tkl))
| TTName -> MayRecNo (Aentry Prim.name)
| TTOpenBinderList -> MayRecNo (Aentry Constr.open_binders)
| TTBigint -> MayRecNo (Aentry Prim.bigint)
| TTReference -> MayRecNo (Aentry Constr.global)

let interp_entry forpat e = match e with
| ETProdName -> TTAny TTName
| ETProdReference -> TTAny TTReference
| ETProdBigint -> TTAny TTBigint
| ETProdConstr (s,p) -> TTAny (TTConstr (s, p, forpat))
| ETProdPattern p -> TTAny (TTPattern p)
| ETProdConstrList (p, tkl) -> TTAny (TTConstrList (p, tkl, forpat))
| ETProdBinderList ETBinderOpen -> TTAny TTOpenBinderList
| ETProdBinderList (ETBinderClosed tkl) -> TTAny (TTClosedBinderList tkl)

let cases_pattern_expr_of_name { CAst.loc; v = na } = CAst.make ?loc @@ match na with
  | Anonymous -> CPatAtom None
  | Name id   -> CPatAtom (Some (qualid_of_ident ?loc id))

type 'r env = {
  constrs : 'r list;
  constrlists : 'r list list;
  binders : cases_pattern_expr list;
  binderlists : local_binder_expr list list;
}

let push_constr subst v = { subst with constrs = v :: subst.constrs }

let push_item : type s r. s target -> (s, r) entry -> s env -> r -> s env = fun forpat e subst v ->
match e with
| TTConstr _ -> push_constr subst v
| TTName ->
  begin match forpat with
  | ForConstr -> { subst with binders = cases_pattern_expr_of_name v :: subst.binders }
  | ForPattern -> push_constr subst (cases_pattern_expr_of_name v)
  end
| TTPattern _ ->
  begin match forpat with
  | ForConstr -> { subst with binders = v :: subst.binders }
  | ForPattern -> push_constr subst v
  end
| TTOpenBinderList -> { subst with binderlists = v :: subst.binderlists }
| TTClosedBinderList _ -> { subst with binderlists = List.flatten v :: subst.binderlists }
| TTBigint ->
  begin match forpat with
  | ForConstr ->  push_constr subst (CAst.make @@ CPrim (Numeral (SPlus,NumTok.int v)))
  | ForPattern -> push_constr subst (CAst.make @@ CPatPrim (Numeral (SPlus,NumTok.int v)))
  end
| TTReference ->
  begin match forpat with
  | ForConstr  -> push_constr subst (CAst.make @@ CRef (v, None))
  | ForPattern -> push_constr subst (CAst.make @@ CPatAtom (Some v))
  end
| TTConstrList _ -> { subst with constrlists = v :: subst.constrlists }

type (_, _) ty_symbol =
| TyTerm : string Tok.p -> ('s, string) ty_symbol
| TyNonTerm : 's target * ('s, 'a) entry * ('s, 'a) mayrec_symbol * bool -> ('s, 'a) ty_symbol

type ('self, _, 'r) ty_rule =
| TyStop : ('self, 'r, 'r) ty_rule
| TyNext : ('self, 'a, 'r) ty_rule * ('self, 'b) ty_symbol -> ('self, 'b -> 'a, 'r) ty_rule
| TyMark : int * bool * int * ('self, 'a, 'r) ty_rule -> ('self, 'a, 'r) ty_rule

type 'r gen_eval = Loc.t -> 'r env -> 'r

let rec ty_eval : type s a. (s, a, Loc.t -> s) ty_rule -> s gen_eval -> s env -> a = function
| TyStop ->
  fun f env loc -> f loc env
| TyNext (rem, TyTerm _) ->
  fun f env _ -> ty_eval rem f env
| TyNext (rem, TyNonTerm (_, _, _, false)) ->
  fun f env _ -> ty_eval rem f env
| TyNext (rem, TyNonTerm (forpat, e, _, true)) ->
  fun f env v ->
    ty_eval rem f (push_item forpat e env v)
| TyMark (n, b, p, rem) ->
  fun f env ->
    let heads, constrs = List.chop n env.constrs in
    let constrlists, constrs =
      if b then
         (* We rearrange constrs = c1..cn rem and constrlists = [d1..dr e1..ep] rem' into
            constrs = e1..ep rem and constrlists [c1..cn d1..dr] rem' *)
         let constrlist = List.hd env.constrlists in
         let constrlist, tail = List.chop (List.length constrlist - p) constrlist in
         (heads @ constrlist) :: List.tl env.constrlists, tail @ constrs
      else
         (* We rearrange constrs = c1..cn e1..ep rem into
            constrs = e1..ep rem and add a constr list [c1..cn] *)
        let constrlist, tail = List.chop (n - p) heads in
        constrlist :: env.constrlists, tail @ constrs
    in
    ty_eval rem f { env with constrs; constrlists; } 

type ('s, 'a, 'r) mayrec_rule =
| MayRecRNo : ('s, Extend.norec, 'a, 'r) Extend.rule -> ('s, 'a, 'r) mayrec_rule
| MayRecRMay : ('s, Extend.mayrec, 'a, 'r) Extend.rule -> ('s, 'a, 'r) mayrec_rule

let rec ty_erase : type s a r. (s, a, r) ty_rule -> (s, a, r) mayrec_rule = function
| TyStop -> MayRecRNo Stop
| TyMark (_, _, _, r) -> ty_erase r
| TyNext (rem, TyTerm tok) ->
   begin match ty_erase rem with
   | MayRecRNo rem -> MayRecRMay (Next (rem, Atoken tok))
   | MayRecRMay rem -> MayRecRMay (Next (rem, Atoken tok)) end
| TyNext (rem, TyNonTerm (_, _, s, _)) ->
   begin match ty_erase rem, s with
   | MayRecRNo rem, MayRecNo s -> MayRecRMay (Next (rem, s))
   | MayRecRNo rem, MayRecMay s -> MayRecRMay (Next (rem, s))
   | MayRecRMay rem, MayRecNo s -> MayRecRMay (Next (rem, s))
   | MayRecRMay rem, MayRecMay s -> MayRecRMay (Next (rem, s)) end

type ('self, 'r) any_ty_rule =
| AnyTyRule : ('self, 'act, Loc.t -> 'r) ty_rule -> ('self, 'r) any_ty_rule

let make_ty_rule assoc from forpat prods =
  let rec make_ty_rule = function
  | [] -> AnyTyRule TyStop
  | GramConstrTerminal tok :: rem ->
    let AnyTyRule r = make_ty_rule rem in
    AnyTyRule (TyNext (r, TyTerm tok))
  | GramConstrNonTerminal (e, var) :: rem ->
    let AnyTyRule r = make_ty_rule rem in
    let TTAny e = interp_entry forpat e in
    let s = symbol_of_entry assoc from e in
    let bind = match var with None -> false | Some _ -> true in
    AnyTyRule (TyNext (r, TyNonTerm (forpat, e, s, bind)))
  | GramConstrListMark (n, b, p) :: rem ->
    let AnyTyRule r = make_ty_rule rem in
    AnyTyRule (TyMark (n, b, p, r))
  in
  make_ty_rule (List.rev prods)

let target_to_bool : type r. r target -> bool = function
| ForConstr -> false
| ForPattern -> true

let prepare_empty_levels forpat (where,(pos,p4assoc,name,reinit)) =
  let empty = (pos, [(name, p4assoc, [])]) in
  ExtendRule (target_entry where forpat, reinit, empty)

let rec pure_sublevels' custom assoc from forpat level = function
| [] -> []
| GramConstrNonTerminal (e,_) :: rem ->
   let rem = pure_sublevels' custom assoc from forpat level rem in
   let push where p rem =
     match symbol_of_target custom p assoc from forpat with
     | MayRecNo (Aentryl (_,i)) when level <> Some (int_of_string i) -> (where,int_of_string i) :: rem
     | _ -> rem in
   (match e with
   | ETProdPattern i -> push InConstrEntry (NumLevel i,InternalProd) rem
   | ETProdConstr (s,p) -> push s p rem
   | _ -> rem)
| (GramConstrTerminal _ | GramConstrListMark _) :: rem -> pure_sublevels' custom assoc from forpat level rem

let make_act : type r. r target -> _ -> r gen_eval = function
| ForConstr -> fun notation loc env ->
  let env = (env.constrs, env.constrlists, env.binders, env.binderlists) in
  CAst.make ~loc @@ CNotation (notation, env)
| ForPattern -> fun notation loc env ->
  let env = (env.constrs, env.constrlists) in
  CAst.make ~loc @@ CPatNotation (notation, env, [])

let extend_constr state forpat ng =
  let custom,n,_,_ = ng.notgram_level in
  let assoc = ng.notgram_assoc in
  let (entry, level) = interp_constr_entry_key custom forpat n in
  let fold (accu, state) pt =
    let AnyTyRule r = make_ty_rule assoc n forpat pt in
    let pure_sublevels = pure_sublevels' custom assoc n forpat level pt in
    let isforpat = target_to_bool forpat in
    let needed_levels, state = register_empty_levels state isforpat pure_sublevels in
    let (pos,p4assoc,name,reinit), state = find_position state custom isforpat assoc level in
    let empty_rules = List.map (prepare_empty_levels forpat) needed_levels in
    let empty = { constrs = []; constrlists = []; binders = []; binderlists = [] } in
    let act = ty_eval r (make_act forpat ng.notgram_notation) empty in
    let rule =
      let r = match ty_erase r with
        | MayRecRNo symbs -> Rule (symbs, act)
        | MayRecRMay symbs -> Rule (symbs, act) in
      name, p4assoc, [r] in
    let r = ExtendRule (entry, reinit, (pos, [rule])) in
    (accu @ empty_rules @ [r], state)
  in
  List.fold_left fold ([], state) ng.notgram_prods

let constr_levels = GramState.field ()

let is_disjunctive_pattern_rule ng =
  String.is_sub "( _ | " (snd ng.notgram_notation) 0

let warn_disj_pattern_notation =
  let open Pp in
  let pp ng = str "Use of " ++ Notation.pr_notation ng.notgram_notation ++
              str " Notation is deprecated as it is inconsistent with pattern syntax." in
  CWarnings.create ~name:"disj-pattern-notation" ~category:"notation" ~default:CWarnings.Disabled pp

let extend_constr_notation ng state =
  let levels = match GramState.get state constr_levels with
  | None -> String.Map.add "constr" default_constr_levels String.Map.empty
  | Some lev -> lev
  in
  (* Add the notation in constr *)
  let (r, levels) = extend_constr levels ForConstr ng in
  (* Add the notation in cases_pattern, unless it would disrupt *)
  (* parsing nested disjunctive patterns. *)
  let (r', levels) =
    if is_disjunctive_pattern_rule ng then begin
       warn_disj_pattern_notation ng;
       ([], levels)
    end else extend_constr levels ForPattern ng in
  let state = GramState.set state constr_levels levels in
  (r @ r', state)

let constr_grammar : one_notation_grammar grammar_command =
  create_grammar_command "Notation" extend_constr_notation

let extend_constr_grammar ntn = extend_grammar_command constr_grammar ntn