summaryrefslogtreecommitdiff
path: root/lisp/progmodes/ebnf-abn.el
blob: 88f430ad93779787c3b5581c42d4ea3de4ca274f (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
;;; ebnf-abn.el --- parser for ABNF (Augmented BNF)

;; Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
;;   Free Software Foundation, Inc.

;; Author: Vinicius Jose Latorre <viniciusjl@ig.com.br>
;; Maintainer: Vinicius Jose Latorre <viniciusjl@ig.com.br>
;; Keywords: wp, ebnf, PostScript
;; Version: 1.2
;; Package: ebnf2ps

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.

;;; Commentary:

;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;;
;; This is part of ebnf2ps package.
;;
;; This package defines a parser for ABNF (Augmented BNF).
;;
;; See ebnf2ps.el for documentation.
;;
;;
;; ABNF Syntax
;; -----------
;;
;;	See the URL:
;;	`http://www.ietf.org/rfc/rfc2234.txt'
;;	or
;;	`http://www.faqs.org/rfcs/rfc2234.html'
;;	or
;;	`http://www.rnp.br/ietf/rfc/rfc2234.txt'
;;	("Augmented BNF for Syntax Specifications: ABNF").
;;
;;
;;    rulelist       =  1*( rule / (*c-wsp c-nl) )
;;
;;    rule           =  rulename defined-as elements c-nl
;;			     ; continues if next line starts with white space
;;
;;    rulename       =  ALPHA *(ALPHA / DIGIT / "-")
;;
;;    defined-as     =  *c-wsp ("=" / "=/") *c-wsp
;;			     ; basic rules definition and incremental
;;			     ; alternatives
;;
;;    elements       =  alternation *c-wsp
;;
;;    c-wsp          =  WSP / (c-nl WSP)
;;
;;    c-nl           =  comment / CRLF
;;			     ; comment or newline
;;
;;    comment        =  ";" *(WSP / VCHAR) CRLF
;;
;;    alternation    =  concatenation
;;			*(*c-wsp "/" *c-wsp concatenation)
;;
;;    concatenation  =  repetition *(1*c-wsp repetition)
;;
;;    repetition     =  [repeat] element
;;
;;    repeat         =  1*DIGIT / (*DIGIT "*" *DIGIT)
;;
;;    element        =  rulename / group / option /
;;			char-val / num-val / prose-val
;;
;;    group          =  "(" *c-wsp alternation *c-wsp ")"
;;
;;    option         =  "[" *c-wsp alternation *c-wsp "]"
;;
;;    char-val       =  DQUOTE *(%x20-21 / %x23-7E) DQUOTE
;;			     ; quoted string of SP and VCHAR without DQUOTE
;;
;;    num-val        =  "%" (bin-val / dec-val / hex-val)
;;
;;    bin-val        =  "b" 1*BIT
;;			[ 1*("." 1*BIT) / ("-" 1*BIT) ]
;;			     ; series of concatenated bit values
;;			     ; or single ONEOF range
;;
;;    dec-val        =  "d" 1*DIGIT
;;			[ 1*("." 1*DIGIT) / ("-" 1*DIGIT) ]
;;
;;    hex-val        =  "x" 1*HEXDIG
;;			[ 1*("." 1*HEXDIG) / ("-" 1*HEXDIG) ]
;;
;;    prose-val      =  "<" *(%x20-3D / %x3F-7E) ">"
;;				; bracketed string of SP and VCHAR without
;;				; angles
;;				; prose description, to be used as last resort
;;
;;    ; Core rules -- the coding depends on the system, here is used 7-bit ASCII
;;
;;    ALPHA          =  %x41-5A / %x61-7A
;;				; A-Z / a-z
;;
;;    BIT            =  "0" / "1"
;;
;;    CHAR           =  %x01-7F
;;				; any 7-bit US-ASCII character, excluding NUL
;;
;;    CR             =  %x0D
;;				; carriage return
;;
;;    CRLF           =  CR LF
;;				; Internet standard newline
;;
;;    CTL            =  %x00-1F / %x7F
;;				; controls
;;
;;    DIGIT          =  %x30-39
;;				; 0-9
;;
;;    DQUOTE         =  %x22
;;				; " (Double Quote)
;;
;;    HEXDIG         =  DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
;;
;;    HTAB           =  %x09
;;				; horizontal tab
;;
;;    LF             =  %x0A
;;				; linefeed
;;
;;    LWSP           =  *(WSP / CRLF WSP)
;;				; linear white space (past newline)
;;
;;    OCTET          =  %x00-FF
;;				; 8 bits of data
;;
;;    SP             =  %x20
;;				; space
;;
;;    VCHAR          =  %x21-7E
;;				; visible (printing) characters
;;
;;    WSP            =  SP / HTAB
;;				; white space
;;
;;
;; NOTES:
;;
;; 1. Rules name and terminal strings are case INSENSITIVE.
;;    So, the following rule names are all equals:
;;	 Rule-name,  rule-Name, rule-name, RULE-NAME
;;    Also, the following strings are equals:
;;	 "abc", "ABC", "aBc", "Abc", "aBC", etc.
;;
;; 2. To have a case SENSITIVE string, use the character notation.
;;    For example, to specify the lowercase string "abc", use:
;;	 %d97.98.99
;;
;; 3. There are no implicit spaces between elements, for example, the
;;    following rules:
;;
;;	 foo = %x61  ; a
;;
;;	 bar = %x62  ; b
;;
;;	 mumble = foo bar foo
;;
;;    Are equivalent to the following rule:
;;
;;	 mumble = %x61.62.61
;;
;;    If spaces are needed, it should be explicit specified, like:
;;
;;	spaces = 1*(%x20 / %x09)  ; one or more spaces or tabs
;;
;;	mumble = foo spaces bar spaces foo
;;
;; 4. Lines starting with space or tab are considered a continuation line.
;;    For example, the rule:
;;
;;	 rule = foo
;;	        bar
;;
;;    Is equivalent to:
;;
;;	 rule = foo bar
;;
;;
;; Differences Between ABNF And ebnf2ps ABNF
;; -----------------------------------------
;;
;; Besides the characters that ABNF accepts, ebnf2ps ABNF accepts also the
;; underscore (_) for rule name and european 8-bit accentuated characters (from
;; \240 to \377) for rule name, string and comment.
;;
;;
;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;; Code:


(require 'ebnf-otz)


(defvar ebnf-abn-lex nil
  "Value returned by `ebnf-abn-lex' function.")


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Syntactic analyzer


;;;    rulelist       =  1*( rule / (*c-wsp c-nl) )

(defun ebnf-abn-parser (start)
  "ABNF parser."
  (let ((total (+ (- ebnf-limit start) 1))
	(bias (1- start))
	(origin (point))
	rule-list token rule)
    (goto-char start)
    (setq token (ebnf-abn-lex))
    (and (eq token 'end-of-input)
	 (error "Invalid ABNF file format"))
    (and (eq token 'end-of-rule)
	 (setq token (ebnf-abn-lex)))
    (while (not (eq token 'end-of-input))
      (ebnf-message-float
       "Parsing...%s%%"
       (/ (* (- (point) bias) 100.0) total))
      (setq token (ebnf-abn-rule token)
	    rule  (cdr token)
	    token (car token))
      (or (ebnf-add-empty-rule-list rule)
	  (setq rule-list (cons rule rule-list))))
    (goto-char origin)
    rule-list))


;;;    rule           =  rulename defined-as elements c-nl
;;;			     ; continues if next line starts with white space
;;;
;;;    rulename       =  ALPHA *(ALPHA / DIGIT / "-")
;;;
;;;    defined-as     =  *c-wsp ("=" / "=/") *c-wsp
;;;			     ; basic rules definition and incremental
;;;			     ; alternatives
;;;
;;;    elements       =  alternation *c-wsp
;;;
;;;    c-wsp          =  WSP / (c-nl WSP)
;;;
;;;    c-nl           =  comment / CRLF
;;;			     ; comment or newline
;;;
;;;    comment        =  ";" *(WSP / VCHAR) CRLF


(defun ebnf-abn-rule (token)
  (let ((name ebnf-abn-lex)
	(action ebnf-action)
	elements)
    (setq ebnf-action nil)
    (or (eq token 'non-terminal)
	(error "Invalid rule name"))
    (setq token (ebnf-abn-lex))
    (or (memq token '(equal incremental-alternative))
	(error "Invalid rule: missing `=' or `=/'"))
    (and (eq token 'incremental-alternative)
	 (setq name (concat name " =/")))
    (setq elements (ebnf-abn-alternation))
    (or (memq (car elements) '(end-of-rule end-of-input))
	(error "Invalid rule: there is no end of rule"))
    (setq elements (cdr elements))
    (ebnf-eps-add-production name)
    (cons (ebnf-abn-lex)
	  (ebnf-make-production name elements action))))


;;;    alternation    =  concatenation
;;;			 *(*c-wsp "/" *c-wsp concatenation)


(defun ebnf-abn-alternation ()
  (let (body concatenation)
    (while (eq (car (setq concatenation
			  (ebnf-abn-concatenation (ebnf-abn-lex))))
	       'alternative)
      (setq body (cons (cdr concatenation) body)))
    (ebnf-token-alternative body concatenation)))


;;;    concatenation  =  repetition *(1*c-wsp repetition)


(defun ebnf-abn-concatenation (token)
  (let ((term (ebnf-abn-repetition token))
	seq)
    (or (setq token (car term)
	      term  (cdr term))
	(error "Empty element"))
    (setq seq (cons term seq))
    (while (setq term  (ebnf-abn-repetition token)
		 token (car term)
		 term  (cdr term))
      (setq seq (cons term seq)))
    (cons token
	  (ebnf-token-sequence seq))))


;;;    repetition     =  [repeat] element
;;;
;;;    repeat         =  1*DIGIT / (*DIGIT "*" *DIGIT)


(defun ebnf-abn-repetition (token)
  (let (lower upper)
    ;; INTEGER [ "*" [ INTEGER ] ]
    (when (eq token 'integer)
      (setq lower ebnf-abn-lex
	    token (ebnf-abn-lex))
      (or (eq token 'repeat)
	  (setq upper lower)))
    ;; "*" [ INTEGER ]
    (when (eq token 'repeat)
      ;; only * ==> lower & upper are empty string
      (or lower
	  (setq lower ""
		upper ""))
      (when (eq (setq token (ebnf-abn-lex)) 'integer)
	(setq upper ebnf-abn-lex
	      token (ebnf-abn-lex))))
    (let ((element (ebnf-abn-element token)))
      (cond
       ;; there is a repetition
       (lower
	(or element
	    (error "Missing element repetition"))
	(setq token (ebnf-abn-lex))
	(cond
	 ;; one or more
	 ((and (string= lower "1") (null upper))
	  (cons token (ebnf-make-one-or-more element)))
	 ;; zero or more
	 ((or (and (string= lower "0") (null upper))
	      (and (string= lower "") (string= upper "")))
	  (cons token (ebnf-make-zero-or-more element)))
	 ;; real repetition
	 (t
	  (ebnf-token-repeat lower (cons token element) upper))))
       ;; there is an element
       (element
	(cons (ebnf-abn-lex) element))
       ;; something that caller has to deal
       (t
	(cons token nil))))))


;;;    element        =  rulename / group / option /
;;;			char-val / num-val / prose-val
;;;
;;;    group          =  "(" *c-wsp alternation *c-wsp ")"
;;;
;;;    option         =  "[" *c-wsp alternation *c-wsp "]"
;;;
;;;    char-val       =  DQUOTE *(%x20-21 / %x23-7E) DQUOTE
;;;			     ; quoted string of SP and VCHAR without DQUOTE
;;;
;;;    num-val        =  "%" (bin-val / dec-val / hex-val)
;;;
;;;    bin-val        =  "b" 1*BIT
;;;			[ 1*("." 1*BIT) / ("-" 1*BIT) ]
;;;			     ; series of concatenated bit values
;;;			     ; or single ONEOF range
;;;
;;;    dec-val        =  "d" 1*DIGIT
;;;			[ 1*("." 1*DIGIT) / ("-" 1*DIGIT) ]
;;;
;;;    hex-val        =  "x" 1*HEXDIG
;;;			[ 1*("." 1*HEXDIG) / ("-" 1*HEXDIG) ]
;;;
;;;    prose-val      =  "<" *(%x20-3D / %x3F-7E) ">"
;;;				; bracketed string of SP and VCHAR without
;;;				; angles
;;;				; prose description, to be used as last resort


(defun ebnf-abn-element (token)
  (cond
   ;; terminal
   ((eq token 'terminal)
    (ebnf-make-terminal ebnf-abn-lex))
   ;; non-terminal
   ((eq token 'non-terminal)
    (ebnf-make-non-terminal ebnf-abn-lex))
   ;; group
   ((eq token 'begin-group)
    (let ((body (ebnf-abn-alternation)))
      (or (eq (car body) 'end-group)
	  (error "Missing `)'"))
      (cdr body)))
   ;; optional
   ((eq token 'begin-optional)
    (let ((body (ebnf-abn-alternation)))
      (or (eq (car body) 'end-optional)
	  (error "Missing `]'"))
      (ebnf-token-optional (cdr body))))
   ;; no element
   (t
    nil)
   ))


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Lexical analyzer


(defconst ebnf-abn-token-table (make-vector 256 'error)
  "Vector used to map characters to a lexical token.")


(defun ebnf-abn-initialize ()
  "Initialize EBNF token table."
  ;; control character & control 8-bit character are set to `error'
  (let ((char ?\060))
    ;; digits: 0-9
    (while (< char ?\072)
      (aset ebnf-abn-token-table char 'integer)
      (setq char (1+ char)))
    ;; printable character: A-Z
    (setq char ?\101)
    (while (< char ?\133)
      (aset ebnf-abn-token-table char 'non-terminal)
      (setq char (1+ char)))
    ;; printable character: a-z
    (setq char ?\141)
    (while (< char ?\173)
      (aset ebnf-abn-token-table char 'non-terminal)
      (setq char (1+ char)))
    ;; European 8-bit accentuated characters:
    (setq char ?\240)
    (while (< char ?\400)
      (aset ebnf-abn-token-table char 'non-terminal)
      (setq char (1+ char)))
    ;; Override end of line characters:
    (aset ebnf-abn-token-table ?\n 'end-of-rule) ; [NL] linefeed
    (aset ebnf-abn-token-table ?\r 'end-of-rule) ; [CR] carriage return
    ;; Override space characters:
    (aset ebnf-abn-token-table ?\013 'space) ; [VT] vertical tab
    (aset ebnf-abn-token-table ?\t   'space) ; [HT] horizontal tab
    (aset ebnf-abn-token-table ?\    'space) ; [SP] space
    ;; Override form feed character:
    (aset ebnf-abn-token-table ?\f 'form-feed) ; [FF] form feed
    ;; Override other lexical characters:
    (aset ebnf-abn-token-table ?<  'non-terminal)
    (aset ebnf-abn-token-table ?%  'terminal)
    (aset ebnf-abn-token-table ?\" 'terminal)
    (aset ebnf-abn-token-table ?\( 'begin-group)
    (aset ebnf-abn-token-table ?\) 'end-group)
    (aset ebnf-abn-token-table ?*  'repeat)
    (aset ebnf-abn-token-table ?=  'equal)
    (aset ebnf-abn-token-table ?\[ 'begin-optional)
    (aset ebnf-abn-token-table ?\] 'end-optional)
    (aset ebnf-abn-token-table ?/  'alternative)
    ;; Override comment character:
    (aset ebnf-abn-token-table ?\; 'comment)))


;; replace the range "\240-\377" (see `ebnf-range-regexp').
(defconst ebnf-abn-non-terminal-chars
  (ebnf-range-regexp "-_0-9A-Za-z" ?\240 ?\377))
(defconst ebnf-abn-non-terminal-letter-chars
  (ebnf-range-regexp "A-Za-z" ?\240 ?\377))


(defun ebnf-abn-lex ()
  "Lexical analyzer for ABNF.

Return a lexical token.

See documentation for variable `ebnf-abn-lex'."
  (if (>= (point) ebnf-limit)
      'end-of-input
    (let (token)
      ;; skip spaces and comments
      (while (if (> (following-char) 255)
		 (progn
		   (setq token 'error)
		   nil)
	       (setq token (aref ebnf-abn-token-table (following-char)))
	       (cond
		((eq token 'space)
		 (skip-chars-forward " \013\t" ebnf-limit)
		 (< (point) ebnf-limit))
		((eq token 'comment)
		 (ebnf-abn-skip-comment))
		((eq token 'form-feed)
		 (forward-char)
		 (setq ebnf-action 'form-feed))
		((eq token 'end-of-rule)
		 (ebnf-abn-skip-end-of-rule))
		(t nil)
		)))
      (cond
       ;; end of input
       ((>= (point) ebnf-limit)
	'end-of-input)
       ;; error
       ((eq token 'error)
	(error "Invalid character"))
       ;; end of rule
       ((eq token 'end-of-rule)
	'end-of-rule)
       ;; integer
       ((eq token 'integer)
	(setq ebnf-abn-lex (ebnf-buffer-substring "0-9"))
	'integer)
       ;; terminal: "string" or %[bdx]NNN((.NNN)+|-NNN)?
       ((eq token 'terminal)
	(setq ebnf-abn-lex
	      (if (= (following-char) ?\")
		  (ebnf-abn-string)
		(ebnf-abn-character)))
	'terminal)
       ;; non-terminal: NAME or <NAME>
       ((eq token 'non-terminal)
	(let ((prose-p (= (following-char) ?<)))
	  (when prose-p
	    (forward-char)
	    (or (looking-at ebnf-abn-non-terminal-letter-chars)
		(error "Invalid prose value")))
	  (setq ebnf-abn-lex
		(ebnf-buffer-substring ebnf-abn-non-terminal-chars))
	  (when prose-p
	    (or (= (following-char) ?>)
		(error "Invalid prose value"))
	    (setq ebnf-abn-lex (concat "<" ebnf-abn-lex ">"))))
	'non-terminal)
       ;; equal: =, =/
       ((eq token 'equal)
	(forward-char)
	(if (/= (following-char) ?/)
	    'equal
	  (forward-char)
	  'incremental-alternative))
       ;; miscellaneous: (, ), [, ], /, *
       (t
	(forward-char)
	token)
       ))))


(defun ebnf-abn-skip-end-of-rule ()
  (let (eor-p)
    (while (progn
	     ;; end of rule ==> 2 or more consecutive end of lines
	     (setq eor-p (or (> (skip-chars-forward "\r\n" ebnf-limit) 1)
			     eor-p))
	     ;; skip spaces
	     (skip-chars-forward " \013\t" ebnf-limit)
	     ;; skip comments
	     (and (= (following-char) ?\;)
		  (ebnf-abn-skip-comment))))
    (not eor-p)))


;; replace the range "\177-\237" (see `ebnf-range-regexp').
(defconst ebnf-abn-comment-chars
  (ebnf-range-regexp "^\n\000-\010\016-\037" ?\177 ?\237))


(defun ebnf-abn-skip-comment ()
  (forward-char)
  (cond
   ;; open EPS file
   ((and ebnf-eps-executing (= (following-char) ?\[))
    (ebnf-eps-add-context (ebnf-abn-eps-filename)))
   ;; close EPS file
   ((and ebnf-eps-executing (= (following-char) ?\]))
    (ebnf-eps-remove-context (ebnf-abn-eps-filename)))
   ;; EPS header
   ((and ebnf-eps-executing (= (following-char) ?H))
    (ebnf-eps-header-comment (ebnf-abn-eps-filename)))
   ;; EPS footer
   ((and ebnf-eps-executing (= (following-char) ?F))
    (ebnf-eps-footer-comment (ebnf-abn-eps-filename)))
   ;; any other action in comment
   (t
    (setq ebnf-action (aref ebnf-comment-table (following-char)))
    (skip-chars-forward ebnf-abn-comment-chars ebnf-limit))
   )
  ;; check for a valid end of comment
  (cond ((>= (point) ebnf-limit)
	 nil)
	((= (following-char) ?\n)
	 t)
	(t
	 (error "Invalid character"))
	))


(defun ebnf-abn-eps-filename ()
  (forward-char)
  (ebnf-buffer-substring ebnf-abn-comment-chars))


;; replace the range "\240-\377" (see `ebnf-range-regexp').
(defconst ebnf-abn-string-chars
  (ebnf-range-regexp " -!#-~" ?\240 ?\377))


(defun ebnf-abn-string ()
  (buffer-substring-no-properties
   (progn
     (forward-char)
     (point))
   (progn
     (skip-chars-forward ebnf-abn-string-chars ebnf-limit)
     (or (= (following-char) ?\")
	 (error "Missing `\"'"))
     (prog1
	 (point)
       (forward-char)))))


(defun ebnf-abn-character ()
  ;; %[bdx]NNN((-NNN)|(.NNN)+)?
  (buffer-substring-no-properties
   (point)
   (progn
     (forward-char)
     (let* ((char  (following-char))
	    (chars (cond ((or (= char ?B) (= char ?b)) "01")
			 ((or (= char ?D) (= char ?d)) "0-9")
			 ((or (= char ?X) (= char ?x)) "0-9A-Fa-f")
			 (t (error "Invalid terminal value")))))
       (forward-char)
       (or (> (skip-chars-forward chars ebnf-limit) 0)
	   (error "Invalid terminal value"))
       (if (= (following-char) ?-)
	   (progn
	     (forward-char)
	     (or (> (skip-chars-forward chars ebnf-limit) 0)
		 (error "Invalid terminal value range")))
	 (while (= (following-char) ?.)
	   (forward-char)
	   (or (> (skip-chars-forward chars ebnf-limit) 0)
	       (error "Invalid terminal value")))))
     (point))))


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


(provide 'ebnf-abn)

;; arch-tag: 8d1b3c4d-4226-4393-b9ae-b7ccf07cf779
;;; ebnf-abn.el ends here