aboutsummaryrefslogtreecommitdiffhomepage
path: root/parsing/lexer.ml4
blob: 8e839296198d16b0d37a34b7cea0e29eb2a9c51e (plain)
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
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
(************************************************************************)
(*  v      *   The Coq Proof Assistant  /  The Coq Development Team     *)
(* <O___,, *   INRIA - CNRS - LIX - LRI - PPS - Copyright 1999-2015     *)
(*   \VV/  **************************************************************)
(*    //   *      This file is distributed under the terms of the       *)
(*         *       GNU Lesser General Public License Version 2.1        *)
(************************************************************************)

open Pp
open Util
open Compat
open Tok

(* Dictionaries: trees annotated with string options, each node being a map
   from chars to dictionaries (the subtrees). A trie, in other words. *)

module CharOrd = struct type t = char let compare : char -> char -> int = compare end
module CharMap = Map.Make (CharOrd)

type ttree = {
  node : string option;
  branch : ttree CharMap.t }

let empty_ttree = { node = None; branch = CharMap.empty }

let ttree_add ttree str =
  let rec insert tt i =
    if i == String.length str then
      {node = Some str; branch = tt.branch}
    else
      let c = str.[i] in
      let br =
        match try Some (CharMap.find c tt.branch) with Not_found -> None with
          | Some tt' ->
              CharMap.add c (insert tt' (i + 1)) (CharMap.remove c tt.branch)
          | None ->
              let tt' = {node = None; branch = CharMap.empty} in
              CharMap.add c (insert tt' (i + 1)) tt.branch
      in
      { node = tt.node; branch = br }
  in
  insert ttree 0

(* Search a string in a dictionary: raises [Not_found]
   if the word is not present. *)

let ttree_find ttree str =
  let rec proc_rec tt i =
    if i == String.length str then tt
    else proc_rec (CharMap.find str.[i] tt.branch) (i+1)
  in
  proc_rec ttree 0

(* Removes a string from a dictionary: returns an equal dictionary
   if the word not present. *)
let ttree_remove ttree str =
  let rec remove tt i =
    if i == String.length str then
      {node = None; branch = tt.branch}
    else
      let c = str.[i] in
      let br =
        match try Some (CharMap.find c tt.branch) with Not_found -> None with
          | Some tt' ->
              CharMap.add c (remove tt' (i + 1)) (CharMap.remove c tt.branch)
          | None -> tt.branch
      in
      { node = tt.node; branch = br }
  in
  remove ttree 0


(* Errors occuring while lexing (explained as "Lexer error: ...") *)

module Error = struct

  type t =
    | Illegal_character
    | Unterminated_comment
    | Unterminated_string
    | Undefined_token
    | Bad_token of string
    | UnsupportedUnicode of int

  exception E of t

  let to_string x =
    "Syntax Error: Lexer: " ^
      (match x with
         | Illegal_character -> "Illegal character"
         | Unterminated_comment -> "Unterminated comment"
         | Unterminated_string -> "Unterminated string"
         | Undefined_token -> "Undefined token"
         | Bad_token tok -> Format.sprintf "Bad token %S" tok
         | UnsupportedUnicode x ->
             Printf.sprintf "Unsupported Unicode character (0x%x)" x)

  (* Require to fix the Camlp4 signature *)
  let print ppf x = Pp.pp_with ppf (Pp.str (to_string x))

end
open Error

let err loc str = Loc.raise (Loc.make_loc loc) (Error.E str)

let bad_token str = raise (Error.E (Bad_token str))

(* Lexer conventions on tokens *)

type token_kind =
  | Utf8Token of (Unicode.status * int)
  | AsciiChar
  | EmptyStream

let error_unsupported_unicode_character n unicode cs =
  let bp = Stream.count cs in
  err (bp,bp+n) (UnsupportedUnicode unicode)

let error_utf8 cs =
  let bp = Stream.count cs in
  Stream.junk cs; (* consume the char to avoid read it and fail again *)
  err (bp, bp+1) Illegal_character

let utf8_char_size cs = function
  (* Utf8 leading byte *)
  | '\x00'..'\x7F' -> 1
  | '\xC0'..'\xDF' -> 2
  | '\xE0'..'\xEF' -> 3
  | '\xF0'..'\xF7' -> 4
  | _ (* '\x80'..\xBF'|'\xF8'..'\xFF' *) -> error_utf8 cs

let njunk n = Util.repeat n Stream.junk

let check_utf8_trailing_byte cs c =
  if not (Int.equal (Char.code c land 0xC0) 0x80) then error_utf8 cs

(* Recognize utf8 blocks (of length less than 4 bytes) *)
(* but don't certify full utf8 compliance (e.g. no emptyness check) *)
let lookup_utf8_tail c cs =
  let c1 = Char.code c in
  if Int.equal (c1 land 0x40) 0 || Int.equal (c1 land 0x38) 0x38 then error_utf8 cs
  else
    let n, unicode =
      if Int.equal (c1 land 0x20) 0 then
      match Stream.npeek 2 cs with
      | [_;c2] ->
          check_utf8_trailing_byte cs c2;
          2, (c1 land 0x1F) lsl 6 + (Char.code c2 land 0x3F)
      | _ -> error_utf8 cs
      else if Int.equal (c1 land 0x10) 0 then
      match Stream.npeek 3 cs with
      | [_;c2;c3] ->
          check_utf8_trailing_byte cs c2; check_utf8_trailing_byte cs c3;
          3, (c1 land 0x0F) lsl 12 + (Char.code c2 land 0x3F) lsl 6 +
          (Char.code c3 land 0x3F)
      | _ -> error_utf8 cs
      else match Stream.npeek 4 cs with
      | [_;c2;c3;c4] ->
          check_utf8_trailing_byte cs c2; check_utf8_trailing_byte cs c3;
          check_utf8_trailing_byte cs c4;
          4, (c1 land 0x07) lsl 18 + (Char.code c2 land 0x3F) lsl 12 +
          (Char.code c3 land 0x3F) lsl 6 + (Char.code c4 land 0x3F)
      | _ -> error_utf8 cs
    in
    try Unicode.classify unicode, n
    with Unicode.Unsupported ->
      njunk n cs; error_unsupported_unicode_character n unicode cs

let lookup_utf8 cs =
  match Stream.peek cs with
    | Some ('\x00'..'\x7F') -> AsciiChar
    | Some ('\x80'..'\xFF' as c) -> Utf8Token (lookup_utf8_tail c cs)
    | None -> EmptyStream

let unlocated f x = f x
  (** FIXME: should we still unloc the exception? *)
(*   try f x with Loc.Exc_located (_, exc) -> raise exc *)

let check_keyword str =
  let rec loop_symb = parser
    | [< ' (' ' | '\n' | '\r' | '\t' | '"') >] -> bad_token str
    | [< s >] ->
        match unlocated lookup_utf8 s with
        | Utf8Token (_,n) -> njunk n s; loop_symb s
        | AsciiChar -> Stream.junk s; loop_symb s
        | EmptyStream -> ()
  in
  loop_symb (Stream.of_string str)

let check_keyword_to_add s =
  try check_keyword s
  with Error.E (UnsupportedUnicode unicode) ->
    Flags.if_verbose msg_warning
      (strbrk (Printf.sprintf "Token '%s' contains unicode character 0x%x \
                               which will not be parsable." s unicode))

let check_ident str =
  let rec loop_id intail = parser
    | [< ' ('a'..'z' | 'A'..'Z' | '_'); s >] ->
        loop_id true s
    | [< ' ('0'..'9' | ''') when intail; s >] ->
        loop_id true s
    | [< s >] ->
        match unlocated lookup_utf8 s with
        | Utf8Token (Unicode.Letter, n) -> njunk n s; loop_id true s
        | Utf8Token (Unicode.IdentPart, n) when intail ->
          njunk n s;
          loop_id true s
        | EmptyStream -> ()
        | Utf8Token _ | AsciiChar -> bad_token str
  in
  loop_id false (Stream.of_string str)

let is_ident str =
  try let _ = check_ident str in true with Error.E _ -> false

(* Keyword and symbol dictionary *)
let token_tree = ref empty_ttree

let is_keyword s =
  try match (ttree_find !token_tree s).node with None -> false | Some _ -> true
  with Not_found -> false

let add_keyword str =
  if not (is_keyword str) then
    begin
      check_keyword_to_add str;
      token_tree := ttree_add !token_tree str
    end

let remove_keyword str =
  token_tree := ttree_remove !token_tree str

(* Freeze and unfreeze the state of the lexer *)
type frozen_t = ttree

let freeze () = !token_tree
let unfreeze tt = (token_tree := tt)

(* The string buffering machinery *)

let buff = ref (String.create 80)

let store len x =
  if len >= String.length !buff then
    buff := !buff ^ String.create (String.length !buff);
  !buff.[len] <- x;
  succ len

let rec nstore n len cs =
  if n>0 then nstore (n-1) (store len (Stream.next cs)) cs else len

let get_buff len = String.sub !buff 0 len

(* The classical lexer: idents, numbers, quoted strings, comments *)

let rec ident_tail len = parser
  | [< ' ('a'..'z' | 'A'..'Z' | '0'..'9' | ''' | '_' as c); s >] ->
      ident_tail (store len c) s
  | [< s >] ->
      match lookup_utf8 s with
      | Utf8Token ((Unicode.IdentPart | Unicode.Letter), n) ->
          ident_tail (nstore n len s) s
      | _ -> len

let rec number len = parser
  | [< ' ('0'..'9' as c); s >] -> number (store len c) s
  | [< >] -> len

let rec string in_comments bp len = parser
  | [< ''"'; esc=(parser [<''"' >] -> true | [< >] -> false); s >] ->
      if esc then string in_comments bp (store len '"') s else len
  | [< ''('; s >] ->
      (parser
        | [< ''*'; s >] ->
            string
              (Option.map succ in_comments)
              bp (store (store len '(') '*')
              s
        | [< >] ->
            string in_comments bp (store len '(') s) s
  | [< ''*'; s >] ->
      (parser
        | [< '')'; s >] ->
            let () = match in_comments with
            | Some 0 ->
                msg_warning
                  (strbrk
                     "Not interpreting \"*)\" as the end of current \
                      non-terminated comment because it occurs in a \
                      non-terminated string of the comment.")
            | _ -> ()
            in
            let in_comments = Option.map pred in_comments in
            string in_comments bp (store (store len '*') ')') s
        | [< >] ->
            string in_comments bp (store len '*') s) s
  | [< 'c; s >] -> string in_comments bp (store len c) s
  | [< _ = Stream.empty >] ep -> err (bp, ep) Unterminated_string

(* Utilities for comments in beautify *)
let comment_begin = ref None
let comm_loc bp = match !comment_begin with
| None -> comment_begin := Some bp
| _ -> ()

let current = Buffer.create 8192
let between_com = ref true

type com_state = int option * string * bool
let restore_com_state (o,s,b) =
  comment_begin := o;
  Buffer.clear current; Buffer.add_string current s;
  between_com := b
let dflt_com = (None,"",true)
let com_state () =
  let s = (!comment_begin, Buffer.contents current, !between_com) in
  restore_com_state dflt_com; s

let real_push_char c = Buffer.add_char current c

(* Add a char if it is between two commands, if it is a newline or
   if the last char is not a space itself. *)
let push_char c =
  if
    !between_com || List.mem c ['\n';'\r'] ||
    (List.mem c [' ';'\t']&&
     (Int.equal (Buffer.length current) 0 ||
      not (let s = Buffer.contents current in
           List.mem s.[String.length s - 1] [' ';'\t';'\n';'\r'])))
  then
    real_push_char c

let push_string s = Buffer.add_string current s

let null_comment s =
  let rec null i =
    i<0 || (List.mem s.[i] [' ';'\t';'\n';'\r'] && null (i-1)) in
  null (String.length s - 1)

let comment_stop ep =
  let current_s = Buffer.contents current in
  (if Flags.do_beautify() && Buffer.length current > 0 &&
    (!between_com || not(null_comment current_s)) then
    let bp = match !comment_begin with
        Some bp -> bp
      | None ->
          msgerrnl(str "No begin location for comment '"
                   ++ str current_s ++str"' ending at  "
                   ++ int ep);
          ep-1 in
    Pp.comments := ((bp,ep),current_s) :: !Pp.comments);
  Buffer.clear current;
  comment_begin := None;
  between_com := false

(* Does not unescape!!! *)
let rec comm_string bp = parser
  | [< ''"' >] -> push_string "\""
  | [< ''\\'; _ =
           (parser [< ' ('"' | '\\' as c) >] ->
              let () = match c with
              | '"' -> real_push_char c
              | _ -> ()
              in
              real_push_char c
                 | [< >] -> real_push_char '\\'); s >]
     -> comm_string bp s
  | [< _ = Stream.empty >] ep -> err (bp, ep) Unterminated_string
  | [< 'c; s >] -> real_push_char c; comm_string bp s

let rec comment bp = parser bp2
  | [< ''(';
       _ = (parser
              | [< ''*'; s >] -> push_string "(*"; comment bp s
              | [< >] -> push_string "(" );
       s >] -> comment bp s
  | [< ''*';
       _ = parser
         | [< '')' >] -> push_string "*)";
         | [< s >] -> real_push_char '*'; comment bp s >] -> ()
  | [< ''"'; s >] ->
      if Flags.do_beautify() then (push_string"\"";comm_string bp2 s)
      else ignore (string (Some 0) bp2 0 s);
      comment bp s
  | [< _ = Stream.empty >] ep -> err (bp, ep) Unterminated_comment
  | [< 'z; s >] -> real_push_char z; comment bp s

(* Parse a special token, using the [token_tree] *)

(* Peek as much utf-8 lexemes as possible *)
(* and retain the longest valid special token obtained *)
let rec progress_further last nj tt cs =
  try progress_from_byte last nj tt cs (List.nth (Stream.npeek (nj+1) cs) nj)
  with Failure _ -> last

and update_longest_valid_token last nj tt cs =
  match tt.node with
  | Some _ as last' ->
    stream_njunk nj cs;
    progress_further last' 0 tt cs
  | None ->
    progress_further last nj tt cs

(* nj is the number of char peeked since last valid token *)
(* n the number of char in utf8 block *)
and progress_utf8 last nj n c tt cs =
  try
    let tt = CharMap.find c tt.branch in
    if Int.equal n 1 then
      update_longest_valid_token last (nj+n) tt cs
    else
      match Util.List.skipn (nj+1) (Stream.npeek (nj+n) cs) with
      | l when Int.equal (List.length l) (n - 1) ->
         List.iter (check_utf8_trailing_byte cs) l;
         let tt = List.fold_left (fun tt c -> CharMap.find c tt.branch) tt l in
         update_longest_valid_token last (nj+n) tt cs
      | _ ->
          error_utf8 cs
  with Not_found ->
    last

and progress_from_byte last nj tt cs c =
  progress_utf8 last nj (utf8_char_size cs c) c tt cs

let find_keyword id s =
  let tt = ttree_find !token_tree id in
  match progress_further tt.node 0 tt s with
  | None -> raise Not_found
  | Some c -> KEYWORD c

let process_sequence bp c cs =
  let rec aux n cs =
    match Stream.peek cs with
    | Some c' when c == c' -> Stream.junk cs; aux (n+1) cs
    | _ -> BULLET (String.make n c), (bp, Stream.count cs)
  in
  aux 1 cs

(* Must be a special token *)
let process_chars bp c cs =
  let t = progress_from_byte None (-1) !token_tree cs c in
  let ep = Stream.count cs in
  match t with
    | Some t -> (KEYWORD t, (bp, ep))
    | None ->
        let ep' = bp + utf8_char_size cs c in
        njunk (ep' - ep) cs;
        err (bp, ep') Undefined_token

let token_of_special c s = match c with
  | '$' -> METAIDENT s
  | '.' -> FIELD s
  | _ -> assert false

(* Parse what follows a dot / a dollar *)

let parse_after_special c bp =
  parser
  | [< ' ('a'..'z' | 'A'..'Z' | '_' as d); len = ident_tail (store 0 d) >] ->
      token_of_special c (get_buff len)
  | [< s >] ->
      match lookup_utf8 s with
      | Utf8Token (Unicode.Letter, n) ->
          token_of_special c (get_buff (ident_tail (nstore n 0 s) s))
      | AsciiChar | Utf8Token _ | EmptyStream -> fst (process_chars bp c s)

(* Parse what follows a question mark *)

let parse_after_qmark bp s =
  match Stream.peek s with
    | Some ('a'..'z' | 'A'..'Z' | '_') -> LEFTQMARK
    | None -> KEYWORD "?"
    | _ ->
        match lookup_utf8 s with
          | Utf8Token (Unicode.Letter, _) -> LEFTQMARK
          | AsciiChar | Utf8Token _ | EmptyStream ->
            fst (process_chars bp '?' s)

let blank_or_eof cs =
  match Stream.peek cs with
    | None -> true
    | Some (' ' | '\t' | '\n' |'\r') -> true
    | _ -> false

(* Parse a token in a char stream *)

let rec next_token = parser bp
  | [< '' ' | '\t' | '\n' |'\r' as c; s >] ->
      comm_loc bp; push_char c; next_token s
  | [< ''$' as c; t = parse_after_special c bp >] ep ->
      comment_stop bp; (t, (ep, bp))
  | [< ''.' as c; t = parse_after_special c bp; s >] ep ->
      comment_stop bp;
      (* We enforce that "." should either be part of a larger keyword,
         for instance ".(", or followed by a blank or eof. *)
      let () = match t with
      | KEYWORD ("." | "...") ->
        if not (blank_or_eof s) then err (bp,ep+1) Undefined_token;
        between_com := true;
      | _ -> ()
      in
      (t, (bp,ep))
  | [< ' ('-'|'+'|'*' as c); s >] ->
      let t,new_between_com =
        if !between_com then process_sequence bp c s,true
        else process_chars bp c s,false
      in
      comment_stop bp; between_com := new_between_com; t
  | [< ''?'; s >] ep ->
      let t = parse_after_qmark bp s in comment_stop bp; (t, (ep, bp))
  | [< ' ('a'..'z' | 'A'..'Z' | '_' as c);
       len = ident_tail (store 0 c); s >] ep ->
      let id = get_buff len in
      comment_stop bp;
      (try find_keyword id s with Not_found -> IDENT id), (bp, ep)
  | [< ' ('0'..'9' as c); len = number (store 0 c) >] ep ->
      comment_stop bp;
      (INT (get_buff len), (bp, ep))
  | [< ''\"'; len = string None bp 0 >] ep ->
      comment_stop bp;
      (STRING (get_buff len), (bp, ep))
  | [< ' ('(' as c);
      t = parser
        | [< ''*'; s >] ->
            comm_loc bp;
            push_string "(*";
            comment bp s;
            next_token s
        | [< t = process_chars bp c >] -> comment_stop bp; t >] ->
      t
  | [< s >] ->
      match lookup_utf8 s with
        | Utf8Token (Unicode.Letter, n) ->
            let len = ident_tail (nstore n 0 s) s in
            let id = get_buff len in
            let ep = Stream.count s in
            comment_stop bp;
            (try find_keyword id s with Not_found -> IDENT id), (bp, ep)
        | AsciiChar | Utf8Token ((Unicode.Symbol | Unicode.IdentPart), _) ->
            let t = process_chars bp (Stream.next s) s in
            let new_between_com = match t with
              (KEYWORD ("{"|"}"),_) -> !between_com | _ -> false in
            comment_stop bp; between_com := new_between_com; t
        | EmptyStream ->
            comment_stop bp; (EOI, (bp, bp + 1))

(* (* Debug: uncomment this for tracing tokens seen by coq...*)
let next_token s =
  let (t,(bp,ep)) = next_token s in Printf.eprintf "[%s]\n%!" (Tok.to_string t);
  (t,(bp,ep))
*)

(* Location table system for creating tables associating a token count
   to its location in a char stream (the source) *)

let locerr () = invalid_arg "Lexer: location function"

let loct_create () = Hashtbl.create 207

let loct_func loct i =
  try Hashtbl.find loct i with Not_found -> locerr ()

let loct_add loct i loc = Hashtbl.add loct i loc

let current_location_table = ref (loct_create ())

type location_table = (int, CompatLoc.t) Hashtbl.t
let location_table () = !current_location_table
let restore_location_table t = current_location_table := t

(** {6 The lexer of Coq} *)

(** Note: removing a token.
   We do nothing because [remove_token] is called only when removing a grammar
   rule with [Grammar.delete_rule]. The latter command is called only when
   unfreezing the state of the grammar entries (see GRAMMAR summary, file
   env/metasyntax.ml). Therefore, instead of removing tokens one by one,
   we unfreeze the state of the lexer. This restores the behaviour of the
   lexer. B.B. *)

IFDEF CAMLP5 THEN

type te = Tok.t

(** Names of tokens, for this lexer, used in Grammar error messages *)

let token_text = function
  | ("", t) -> "'" ^ t ^ "'"
  | ("IDENT", "") -> "identifier"
  | ("IDENT", t) -> "'" ^ t ^ "'"
  | ("INT", "") -> "integer"
  | ("INT", s) -> "'" ^ s ^ "'"
  | ("STRING", "") -> "string"
  | ("EOI", "") -> "end of input"
  | (con, "") -> con
  | (con, prm) -> con ^ " \"" ^ prm ^ "\""

let func cs =
  let loct = loct_create () in
  let ts =
    Stream.from
      (fun i ->
         let (tok, loc) = next_token cs in
         loct_add loct i (make_loc loc); Some tok)
  in
  current_location_table := loct;
  (ts, loct_func loct)

let lexer = {
  Token.tok_func = func;
  Token.tok_using =
    (fun pat -> match Tok.of_pattern pat with
       | KEYWORD s -> add_keyword s
       | _ -> ());
  Token.tok_removing = (fun _ -> ());
  Token.tok_match = Tok.match_pattern;
  Token.tok_comm = None;
  Token.tok_text = token_text }

ELSE (* official camlp4 for ocaml >= 3.10 *)

module M_ = Camlp4.ErrorHandler.Register (Error)

module Loc = CompatLoc
module Token = struct
  include Tok (* Cf. tok.ml *)
  module Loc = CompatLoc
  module Error = Camlp4.Struct.EmptyError
  module Filter = struct
    type token_filter = (Tok.t * Loc.t) Stream.t -> (Tok.t * Loc.t) Stream.t
    type t = unit
    let mk _is_kwd = ()
    let keyword_added () kwd _ = add_keyword kwd
    let keyword_removed () _ = ()
    let filter () x = x
    let define_filter () _ = ()
  end
end

let mk () _init_loc(*FIXME*) cs =
  let loct = loct_create () in
  let rec self =
    parser i
       [< (tok, loc) = next_token; s >] ->
          let loc = make_loc loc in
            loct_add loct i loc;
            [< '(tok, loc); self s >]
      | [< >] -> [< >]
  in current_location_table := loct; self cs

END

(** Terminal symbols interpretation *)

let is_ident_not_keyword s =
  is_ident s && not (is_keyword s)

let is_number s =
  let rec aux i =
    Int.equal (String.length s) i ||
    match s.[i] with '0'..'9' -> aux (i+1) | _ -> false
  in aux 0

let strip s =
  let len =
    let rec loop i len =
      if Int.equal i (String.length s) then len
      else if s.[i] == ' ' then loop (i + 1) len
      else loop (i + 1) (len + 1)
    in
    loop 0 0
  in
  if len == String.length s then s
  else
    let s' = String.create len in
    let rec loop i i' =
      if i == String.length s then s'
      else if s.[i] == ' ' then loop (i + 1) i'
      else begin s'.[i'] <- s.[i]; loop (i + 1) (i' + 1) end
    in
    loop 0 0

let terminal s =
  let s = strip s in
  let () = match s with "" -> Errors.error "empty token." | _ -> () in
  if is_ident_not_keyword s then IDENT s
  else if is_number s then INT s
  else KEYWORD s