lisp/progmodes/ebnf-abn.el

   1 ;;; ebnf-abn.el --- parser for ABNF (Augmented BNF)
   2
   3 ;; Copyright (C) 2001-2015 Free Software Foundation, Inc.
   4
   5 ;; Author: Vinicius Jose Latorre <viniciusjl@ig.com.br>
   6 ;; Maintainer: Vinicius Jose Latorre <viniciusjl@ig.com.br>
   7 ;; Keywords: wp, ebnf, PostScript
   8 ;; Old-Version: 1.2
   9 ;; Package: ebnf2ps
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software: you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation, either version 3 of the License, or
  16 ;; (at your option) any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
  25
  26 ;;; Commentary:
  27
  28 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  29 ;;
  30 ;;
  31 ;; This is part of ebnf2ps package.
  32 ;;
  33 ;; This package defines a parser for ABNF (Augmented BNF).
  34 ;;
  35 ;; See ebnf2ps.el for documentation.
  36 ;;
  37 ;;
  38 ;; ABNF Syntax
  39 ;; -----------
  40 ;;
  41 ;;      See the URL:
  42 ;;      `http://www.ietf.org/rfc/rfc2234.txt'
  43 ;;      or
  44 ;;      `http://www.faqs.org/rfcs/rfc2234.html'
  45 ;;      or
  46 ;;      `http://www.rnp.br/ietf/rfc/rfc2234.txt'
  47 ;;      ("Augmented BNF for Syntax Specifications: ABNF").
  48 ;;
  49 ;;
  50 ;;    rulelist       =  1*( rule / (*c-wsp c-nl) )
  51 ;;
  52 ;;    rule           =  rulename defined-as elements c-nl
  53 ;;                           ; continues if next line starts with white space
  54 ;;
  55 ;;    rulename       =  ALPHA *(ALPHA / DIGIT / "-")
  56 ;;
  57 ;;    defined-as     =  *c-wsp ("=" / "=/") *c-wsp
  58 ;;                           ; basic rules definition and incremental
  59 ;;                           ; alternatives
  60 ;;
  61 ;;    elements       =  alternation *c-wsp
  62 ;;
  63 ;;    c-wsp          =  WSP / (c-nl WSP)
  64 ;;
  65 ;;    c-nl           =  comment / CRLF
  66 ;;                           ; comment or newline
  67 ;;
  68 ;;    comment        =  ";" *(WSP / VCHAR) CRLF
  69 ;;
  70 ;;    alternation    =  concatenation
  71 ;;                      *(*c-wsp "/" *c-wsp concatenation)
  72 ;;
  73 ;;    concatenation  =  repetition *(1*c-wsp repetition)
  74 ;;
  75 ;;    repetition     =  [repeat] element
  76 ;;
  77 ;;    repeat         =  1*DIGIT / (*DIGIT "*" *DIGIT)
  78 ;;
  79 ;;    element        =  rulename / group / option /
  80 ;;                      char-val / num-val / prose-val
  81 ;;
  82 ;;    group          =  "(" *c-wsp alternation *c-wsp ")"
  83 ;;
  84 ;;    option         =  "[" *c-wsp alternation *c-wsp "]"
  85 ;;
  86 ;;    char-val       =  DQUOTE *(%x20-21 / %x23-7E) DQUOTE
  87 ;;                           ; quoted string of SP and VCHAR without DQUOTE
  88 ;;
  89 ;;    num-val        =  "%" (bin-val / dec-val / hex-val)
  90 ;;
  91 ;;    bin-val        =  "b" 1*BIT
  92 ;;                      [ 1*("." 1*BIT) / ("-" 1*BIT) ]
  93 ;;                           ; series of concatenated bit values
  94 ;;                           ; or single ONEOF range
  95 ;;
  96 ;;    dec-val        =  "d" 1*DIGIT
  97 ;;                      [ 1*("." 1*DIGIT) / ("-" 1*DIGIT) ]
  98 ;;
  99 ;;    hex-val        =  "x" 1*HEXDIG
 100 ;;                      [ 1*("." 1*HEXDIG) / ("-" 1*HEXDIG) ]
 101 ;;
 102 ;;    prose-val      =  "<" *(%x20-3D / %x3F-7E) ">"
 103 ;;                              ; bracketed string of SP and VCHAR without
 104 ;;                              ; angles
 105 ;;                              ; prose description, to be used as last resort
 106 ;;
 107 ;;    ; Core rules -- the coding depends on the system, here is used 7-bit ASCII
 108 ;;
 109 ;;    ALPHA          =  %x41-5A / %x61-7A
 110 ;;                              ; A-Z / a-z
 111 ;;
 112 ;;    BIT            =  "0" / "1"
 113 ;;
 114 ;;    CHAR           =  %x01-7F
 115 ;;                              ; any 7-bit US-ASCII character, excluding NUL
 116 ;;
 117 ;;    CR             =  %x0D
 118 ;;                              ; carriage return
 119 ;;
 120 ;;    CRLF           =  CR LF
 121 ;;                              ; Internet standard newline
 122 ;;
 123 ;;    CTL            =  %x00-1F / %x7F
 124 ;;                              ; controls
 125 ;;
 126 ;;    DIGIT          =  %x30-39
 127 ;;                              ; 0-9
 128 ;;
 129 ;;    DQUOTE         =  %x22
 130 ;;                              ; " (Double Quote)
 131 ;;
 132 ;;    HEXDIG         =  DIGIT / "A" / "B" / "C" / "D" / "E" / "F"
 133 ;;
 134 ;;    HTAB           =  %x09
 135 ;;                              ; horizontal tab
 136 ;;
 137 ;;    LF             =  %x0A
 138 ;;                              ; linefeed
 139 ;;
 140 ;;    LWSP           =  *(WSP / CRLF WSP)
 141 ;;                              ; linear white space (past newline)
 142 ;;
 143 ;;    OCTET          =  %x00-FF
 144 ;;                              ; 8 bits of data
 145 ;;
 146 ;;    SP             =  %x20
 147 ;;                              ; space
 148 ;;
 149 ;;    VCHAR          =  %x21-7E
 150 ;;                              ; visible (printing) characters
 151 ;;
 152 ;;    WSP            =  SP / HTAB
 153 ;;                              ; white space
 154 ;;
 155 ;;
 156 ;; NOTES:
 157 ;;
 158 ;; 1. Rules name and terminal strings are case INSENSITIVE.
 159 ;;    So, the following rule names are all equals:
 160 ;;       Rule-name,  rule-Name, rule-name, RULE-NAME
 161 ;;    Also, the following strings are equals:
 162 ;;       "abc", "ABC", "aBc", "Abc", "aBC", etc.
 163 ;;
 164 ;; 2. To have a case SENSITIVE string, use the character notation.
 165 ;;    For example, to specify the lowercase string "abc", use:
 166 ;;       %d97.98.99
 167 ;;
 168 ;; 3. There are no implicit spaces between elements, for example, the
 169 ;;    following rules:
 170 ;;
 171 ;;       foo = %x61  ; a
 172 ;;
 173 ;;       bar = %x62  ; b
 174 ;;
 175 ;;       mumble = foo bar foo
 176 ;;
 177 ;;    Are equivalent to the following rule:
 178 ;;
 179 ;;       mumble = %x61.62.61
 180 ;;
 181 ;;    If spaces are needed, it should be explicit specified, like:
 182 ;;
 183 ;;      spaces = 1*(%x20 / %x09)  ; one or more spaces or tabs
 184 ;;
 185 ;;      mumble = foo spaces bar spaces foo
 186 ;;
 187 ;; 4. Lines starting with space or tab are considered a continuation line.
 188 ;;    For example, the rule:
 189 ;;
 190 ;;       rule = foo
 191 ;;              bar
 192 ;;
 193 ;;    Is equivalent to:
 194 ;;
 195 ;;       rule = foo bar
 196 ;;
 197 ;;
 198 ;; Differences Between ABNF And ebnf2ps ABNF
 199 ;; -----------------------------------------
 200 ;;
 201 ;; Besides the characters that ABNF accepts, ebnf2ps ABNF accepts also the
 202 ;; underscore (_) for rule name and european 8-bit accentuated characters (from
 203 ;; \240 to \377) for rule name, string and comment.
 204 ;;
 205 ;;
 206 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 207
 208 ;;; Code:
 209
 210
 211 (require 'ebnf-otz)
 212
 213
 214 (defvar ebnf-abn-lex nil
 215   "Value returned by `ebnf-abn-lex' function.")
 216
 217 \f
 218 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 219 ;; Syntactic analyzer
 220
 221
 222 ;;;    rulelist       =  1*( rule / (*c-wsp c-nl) )
 223
 224 (defun ebnf-abn-parser (start)
 225   "ABNF parser."
 226   (let ((total (+ (- ebnf-limit start) 1))
 227         (bias (1- start))
 228         (origin (point))
 229         rule-list token rule)
 230     (goto-char start)
 231     (setq token (ebnf-abn-lex))
 232     (and (eq token 'end-of-input)
 233          (error "Invalid ABNF file format"))
 234     (and (eq token 'end-of-rule)
 235          (setq token (ebnf-abn-lex)))
 236     (while (not (eq token 'end-of-input))
 237       (ebnf-message-float
 238        "Parsing...%s%%"
 239        (/ (* (- (point) bias) 100.0) total))
 240       (setq token (ebnf-abn-rule token)
 241             rule  (cdr token)
 242             token (car token))
 243       (or (ebnf-add-empty-rule-list rule)
 244           (setq rule-list (cons rule rule-list))))
 245     (goto-char origin)
 246     rule-list))
 247
 248
 249 ;;;    rule           =  rulename defined-as elements c-nl
 250 ;;;                          ; continues if next line starts with white space
 251 ;;;
 252 ;;;    rulename       =  ALPHA *(ALPHA / DIGIT / "-")
 253 ;;;
 254 ;;;    defined-as     =  *c-wsp ("=" / "=/") *c-wsp
 255 ;;;                          ; basic rules definition and incremental
 256 ;;;                          ; alternatives
 257 ;;;
 258 ;;;    elements       =  alternation *c-wsp
 259 ;;;
 260 ;;;    c-wsp          =  WSP / (c-nl WSP)
 261 ;;;
 262 ;;;    c-nl           =  comment / CRLF
 263 ;;;                          ; comment or newline
 264 ;;;
 265 ;;;    comment        =  ";" *(WSP / VCHAR) CRLF
 266
 267
 268 (defun ebnf-abn-rule (token)
 269   (let ((name ebnf-abn-lex)
 270         (action ebnf-action)
 271         elements)
 272     (setq ebnf-action nil)
 273     (or (eq token 'non-terminal)
 274         (error "Invalid rule name"))
 275     (setq token (ebnf-abn-lex))
 276     (or (memq token '(equal incremental-alternative))
 277         (error "Invalid rule: missing `=' or `=/'"))
 278     (and (eq token 'incremental-alternative)
 279          (setq name (concat name " =/")))
 280     (setq elements (ebnf-abn-alternation))
 281     (or (memq (car elements) '(end-of-rule end-of-input))
 282         (error "Invalid rule: there is no end of rule"))
 283     (setq elements (cdr elements))
 284     (ebnf-eps-add-production name)
 285     (cons (ebnf-abn-lex)
 286           (ebnf-make-production name elements action))))
 287
 288
 289 ;;;    alternation    =  concatenation
 290 ;;;                      *(*c-wsp "/" *c-wsp concatenation)
 291
 292
 293 (defun ebnf-abn-alternation ()
 294   (let (body concatenation)
 295     (while (eq (car (setq concatenation
 296                           (ebnf-abn-concatenation (ebnf-abn-lex))))
 297                'alternative)
 298       (setq body (cons (cdr concatenation) body)))
 299     (ebnf-token-alternative body concatenation)))
 300
 301
 302 ;;;    concatenation  =  repetition *(1*c-wsp repetition)
 303
 304
 305 (defun ebnf-abn-concatenation (token)
 306   (let ((term (ebnf-abn-repetition token))
 307         seq)
 308     (or (setq token (car term)
 309               term  (cdr term))
 310         (error "Empty element"))
 311     (setq seq (cons term seq))
 312     (while (setq term  (ebnf-abn-repetition token)
 313                  token (car term)
 314                  term  (cdr term))
 315       (setq seq (cons term seq)))
 316     (cons token
 317           (ebnf-token-sequence seq))))
 318
 319
 320 ;;;    repetition     =  [repeat] element
 321 ;;;
 322 ;;;    repeat         =  1*DIGIT / (*DIGIT "*" *DIGIT)
 323
 324
 325 (defun ebnf-abn-repetition (token)
 326   (let (lower upper)
 327     ;; INTEGER [ "*" [ INTEGER ] ]
 328     (when (eq token 'integer)
 329       (setq lower ebnf-abn-lex
 330             token (ebnf-abn-lex))
 331       (or (eq token 'repeat)
 332           (setq upper lower)))
 333     ;; "*" [ INTEGER ]
 334     (when (eq token 'repeat)
 335       ;; only * ==> lower & upper are empty string
 336       (or lower
 337           (setq lower ""
 338                 upper ""))
 339       (when (eq (setq token (ebnf-abn-lex)) 'integer)
 340         (setq upper ebnf-abn-lex
 341               token (ebnf-abn-lex))))
 342     (let ((element (ebnf-abn-element token)))
 343       (cond
 344        ;; there is a repetition
 345        (lower
 346         (or element
 347             (error "Missing element repetition"))
 348         (setq token (ebnf-abn-lex))
 349         (cond
 350          ;; one or more
 351          ((and (string= lower "1") (null upper))
 352           (cons token (ebnf-make-one-or-more element)))
 353          ;; zero or more
 354          ((or (and (string= lower "0") (null upper))
 355               (and (string= lower "") (string= upper "")))
 356           (cons token (ebnf-make-zero-or-more element)))
 357          ;; real repetition
 358          (t
 359           (ebnf-token-repeat lower (cons token element) upper))))
 360        ;; there is an element
 361        (element
 362         (cons (ebnf-abn-lex) element))
 363        ;; something that caller has to deal
 364        (t
 365         (cons token nil))))))
 366
 367
 368 ;;;    element        =  rulename / group / option /
 369 ;;;                     char-val / num-val / prose-val
 370 ;;;
 371 ;;;    group          =  "(" *c-wsp alternation *c-wsp ")"
 372 ;;;
 373 ;;;    option         =  "[" *c-wsp alternation *c-wsp "]"
 374 ;;;
 375 ;;;    char-val       =  DQUOTE *(%x20-21 / %x23-7E) DQUOTE
 376 ;;;                          ; quoted string of SP and VCHAR without DQUOTE
 377 ;;;
 378 ;;;    num-val        =  "%" (bin-val / dec-val / hex-val)
 379 ;;;
 380 ;;;    bin-val        =  "b" 1*BIT
 381 ;;;                     [ 1*("." 1*BIT) / ("-" 1*BIT) ]
 382 ;;;                          ; series of concatenated bit values
 383 ;;;                          ; or single ONEOF range
 384 ;;;
 385 ;;;    dec-val        =  "d" 1*DIGIT
 386 ;;;                     [ 1*("." 1*DIGIT) / ("-" 1*DIGIT) ]
 387 ;;;
 388 ;;;    hex-val        =  "x" 1*HEXDIG
 389 ;;;                     [ 1*("." 1*HEXDIG) / ("-" 1*HEXDIG) ]
 390 ;;;
 391 ;;;    prose-val      =  "<" *(%x20-3D / %x3F-7E) ">"
 392 ;;;                             ; bracketed string of SP and VCHAR without
 393 ;;;                             ; angles
 394 ;;;                             ; prose description, to be used as last resort
 395
 396
 397 (defun ebnf-abn-element (token)
 398   (cond
 399    ;; terminal
 400    ((eq token 'terminal)
 401     (ebnf-make-terminal ebnf-abn-lex))
 402    ;; non-terminal
 403    ((eq token 'non-terminal)
 404     (ebnf-make-non-terminal ebnf-abn-lex))
 405    ;; group
 406    ((eq token 'begin-group)
 407     (let ((body (ebnf-abn-alternation)))
 408       (or (eq (car body) 'end-group)
 409           (error "Missing `)'"))
 410       (cdr body)))
 411    ;; optional
 412    ((eq token 'begin-optional)
 413     (let ((body (ebnf-abn-alternation)))
 414       (or (eq (car body) 'end-optional)
 415           (error "Missing `]'"))
 416       (ebnf-token-optional (cdr body))))
 417    ;; no element
 418    (t
 419     nil)
 420    ))
 421
 422 \f
 423 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 424 ;; Lexical analyzer
 425
 426
 427 (defconst ebnf-abn-token-table (make-vector 256 'error)
 428   "Vector used to map characters to a lexical token.")
 429
 430
 431 (defun ebnf-abn-initialize ()
 432   "Initialize EBNF token table."
 433   ;; control character & control 8-bit character are set to `error'
 434   (let ((char ?\060))
 435     ;; digits: 0-9
 436     (while (< char ?\072)
 437       (aset ebnf-abn-token-table char 'integer)
 438       (setq char (1+ char)))
 439     ;; printable character: A-Z
 440     (setq char ?\101)
 441     (while (< char ?\133)
 442       (aset ebnf-abn-token-table char 'non-terminal)
 443       (setq char (1+ char)))
 444     ;; printable character: a-z
 445     (setq char ?\141)
 446     (while (< char ?\173)
 447       (aset ebnf-abn-token-table char 'non-terminal)
 448       (setq char (1+ char)))
 449     ;; European 8-bit accentuated characters:
 450     (setq char ?\240)
 451     (while (< char ?\400)
 452       (aset ebnf-abn-token-table char 'non-terminal)
 453       (setq char (1+ char)))
 454     ;; Override end of line characters:
 455     (aset ebnf-abn-token-table ?\n 'end-of-rule) ; [NL] linefeed
 456     (aset ebnf-abn-token-table ?\r 'end-of-rule) ; [CR] carriage return
 457     ;; Override space characters:
 458     (aset ebnf-abn-token-table ?\013 'space) ; [VT] vertical tab
 459     (aset ebnf-abn-token-table ?\t   'space) ; [HT] horizontal tab
 460     (aset ebnf-abn-token-table ?\    'space) ; [SP] space
 461     ;; Override form feed character:
 462     (aset ebnf-abn-token-table ?\f 'form-feed) ; [FF] form feed
 463     ;; Override other lexical characters:
 464     (aset ebnf-abn-token-table ?<  'non-terminal)
 465     (aset ebnf-abn-token-table ?%  'terminal)
 466     (aset ebnf-abn-token-table ?\" 'terminal)
 467     (aset ebnf-abn-token-table ?\( 'begin-group)
 468     (aset ebnf-abn-token-table ?\) 'end-group)
 469     (aset ebnf-abn-token-table ?*  'repeat)
 470     (aset ebnf-abn-token-table ?=  'equal)
 471     (aset ebnf-abn-token-table ?\[ 'begin-optional)
 472     (aset ebnf-abn-token-table ?\] 'end-optional)
 473     (aset ebnf-abn-token-table ?/  'alternative)
 474     ;; Override comment character:
 475     (aset ebnf-abn-token-table ?\; 'comment)))
 476
 477
 478 ;; replace the range "\240-\377" (see `ebnf-range-regexp').
 479 (defconst ebnf-abn-non-terminal-chars
 480   (ebnf-range-regexp "-_0-9A-Za-z" ?\240 ?\377))
 481 (defconst ebnf-abn-non-terminal-letter-chars
 482   (ebnf-range-regexp "A-Za-z" ?\240 ?\377))
 483
 484
 485 (defun ebnf-abn-lex ()
 486   "Lexical analyzer for ABNF.
 487
 488 Return a lexical token.
 489
 490 See documentation for variable `ebnf-abn-lex'."
 491   (if (>= (point) ebnf-limit)
 492       'end-of-input
 493     (let (token)
 494       ;; skip spaces and comments
 495       (while (if (> (following-char) 255)
 496                  (progn
 497                    (setq token 'error)
 498                    nil)
 499                (setq token (aref ebnf-abn-token-table (following-char)))
 500                (cond
 501                 ((eq token 'space)
 502                  (skip-chars-forward " \013\t" ebnf-limit)
 503                  (< (point) ebnf-limit))
 504                 ((eq token 'comment)
 505                  (ebnf-abn-skip-comment))
 506                 ((eq token 'form-feed)
 507                  (forward-char)
 508                  (setq ebnf-action 'form-feed))
 509                 ((eq token 'end-of-rule)
 510                  (ebnf-abn-skip-end-of-rule))
 511                 (t nil)
 512                 )))
 513       (cond
 514        ;; end of input
 515        ((>= (point) ebnf-limit)
 516         'end-of-input)
 517        ;; error
 518        ((eq token 'error)
 519         (error "Invalid character"))
 520        ;; end of rule
 521        ((eq token 'end-of-rule)
 522         'end-of-rule)
 523        ;; integer
 524        ((eq token 'integer)
 525         (setq ebnf-abn-lex (ebnf-buffer-substring "0-9"))
 526         'integer)
 527        ;; terminal: "string" or %[bdx]NNN((.NNN)+|-NNN)?
 528        ((eq token 'terminal)
 529         (setq ebnf-abn-lex
 530               (if (= (following-char) ?\")
 531                   (ebnf-abn-string)
 532                 (ebnf-abn-character)))
 533         'terminal)
 534        ;; non-terminal: NAME or <NAME>
 535        ((eq token 'non-terminal)
 536         (let ((prose-p (= (following-char) ?<)))
 537           (when prose-p
 538             (forward-char)
 539             (or (looking-at ebnf-abn-non-terminal-letter-chars)
 540                 (error "Invalid prose value")))
 541           (setq ebnf-abn-lex
 542                 (ebnf-buffer-substring ebnf-abn-non-terminal-chars))
 543           (when prose-p
 544             (or (= (following-char) ?>)
 545                 (error "Invalid prose value"))
 546             (setq ebnf-abn-lex (concat "<" ebnf-abn-lex ">"))))
 547         'non-terminal)
 548        ;; equal: =, =/
 549        ((eq token 'equal)
 550         (forward-char)
 551         (if (/= (following-char) ?/)
 552             'equal
 553           (forward-char)
 554           'incremental-alternative))
 555        ;; miscellaneous: (, ), [, ], /, *
 556        (t
 557         (forward-char)
 558         token)
 559        ))))
 560
 561
 562 (defun ebnf-abn-skip-end-of-rule ()
 563   (let (eor-p)
 564     (while (progn
 565              ;; end of rule ==> 2 or more consecutive end of lines
 566              (setq eor-p (or (> (skip-chars-forward "\r\n" ebnf-limit) 1)
 567                              eor-p))
 568              ;; skip spaces
 569              (skip-chars-forward " \013\t" ebnf-limit)
 570              ;; skip comments
 571              (and (= (following-char) ?\;)
 572                   (ebnf-abn-skip-comment))))
 573     (not eor-p)))
 574
 575
 576 ;; replace the range "\177-\237" (see `ebnf-range-regexp').
 577 (defconst ebnf-abn-comment-chars
 578   (ebnf-range-regexp "^\n\000-\010\016-\037" ?\177 ?\237))
 579
 580
 581 (defun ebnf-abn-skip-comment ()
 582   (forward-char)
 583   (cond
 584    ;; open EPS file
 585    ((and ebnf-eps-executing (= (following-char) ?\[))
 586     (ebnf-eps-add-context (ebnf-abn-eps-filename)))
 587    ;; close EPS file
 588    ((and ebnf-eps-executing (= (following-char) ?\]))
 589     (ebnf-eps-remove-context (ebnf-abn-eps-filename)))
 590    ;; EPS header
 591    ((and ebnf-eps-executing (= (following-char) ?H))
 592     (ebnf-eps-header-comment (ebnf-abn-eps-filename)))
 593    ;; EPS footer
 594    ((and ebnf-eps-executing (= (following-char) ?F))
 595     (ebnf-eps-footer-comment (ebnf-abn-eps-filename)))
 596    ;; any other action in comment
 597    (t
 598     (setq ebnf-action (aref ebnf-comment-table (following-char)))
 599     (skip-chars-forward ebnf-abn-comment-chars ebnf-limit))
 600    )
 601   ;; check for a valid end of comment
 602   (cond ((>= (point) ebnf-limit)
 603          nil)
 604         ((= (following-char) ?\n)
 605          t)
 606         (t
 607          (error "Invalid character"))
 608         ))
 609
 610
 611 (defun ebnf-abn-eps-filename ()
 612   (forward-char)
 613   (ebnf-buffer-substring ebnf-abn-comment-chars))
 614
 615
 616 ;; replace the range "\240-\377" (see `ebnf-range-regexp').
 617 (defconst ebnf-abn-string-chars
 618   (ebnf-range-regexp " -!#-~" ?\240 ?\377))
 619
 620
 621 (defun ebnf-abn-string ()
 622   (buffer-substring-no-properties
 623    (progn
 624      (forward-char)
 625      (point))
 626    (progn
 627      (skip-chars-forward ebnf-abn-string-chars ebnf-limit)
 628      (or (= (following-char) ?\")
 629          (error "Missing `\"'"))
 630      (prog1
 631          (point)
 632        (forward-char)))))
 633
 634
 635 (defun ebnf-abn-character ()
 636   ;; %[bdx]NNN((-NNN)|(.NNN)+)?
 637   (buffer-substring-no-properties
 638    (point)
 639    (progn
 640      (forward-char)
 641      (let* ((char  (following-char))
 642             (chars (cond ((or (= char ?B) (= char ?b)) "01")
 643                          ((or (= char ?D) (= char ?d)) "0-9")
 644                          ((or (= char ?X) (= char ?x)) "0-9A-Fa-f")
 645                          (t (error "Invalid terminal value")))))
 646        (forward-char)
 647        (or (> (skip-chars-forward chars ebnf-limit) 0)
 648            (error "Invalid terminal value"))
 649        (if (= (following-char) ?-)
 650            (progn
 651              (forward-char)
 652              (or (> (skip-chars-forward chars ebnf-limit) 0)
 653                  (error "Invalid terminal value range")))
 654          (while (= (following-char) ?.)
 655            (forward-char)
 656            (or (> (skip-chars-forward chars ebnf-limit) 0)
 657                (error "Invalid terminal value")))))
 658      (point))))
 659
 660 \f
 661 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 662
 663
 664 (provide 'ebnf-abn)
 665
 666 ;;; ebnf-abn.el ends here