lisp/progmodes/ebnf-iso.el

   1 ;;; ebnf-iso --- Parser for ISO EBNF
   2
   3 ;; Copyright (C) 1999, 2000 Free Software Foundation, Inc.
   4
   5 ;; Author:     Vinicius Jose Latorre <vinicius@cpqd.com.br>
   6 ;; Maintainer: Vinicius Jose Latorre <vinicius@cpqd.com.br>
   7 ;; Keywords:   wp, ebnf, PostScript
   8 ;; Time-stamp: <99/11/20 18:04:11 vinicius>
   9 ;; Version:    1.4
  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 2, or (at your option)
  16 ;; 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; see the file COPYING.  If not, write to the
  25 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  26 ;; Boston, MA 02111-1307, USA.
  27
  28 ;;; Commentary:
  29
  30 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
  31 ;;
  32 ;;
  33 ;; This is part of ebnf2ps package.
  34 ;;
  35 ;; This package defines a parser for ISO EBNF.
  36 ;;
  37 ;; See ebnf2ps.el for documentation.
  38 ;;
  39 ;;
  40 ;; ISO EBNF Syntax
  41 ;; ---------------
  42 ;;
  43 ;;      See the URL:
  44 ;;      `http://www.cl.cam.ac.uk/~mgk25/iso-ebnf.html'
  45 ;;      ("International Standard of the ISO EBNF Notation").
  46 ;;
  47 ;;
  48 ;; ISO EBNF = syntax rule, {syntax rule};
  49 ;;
  50 ;; syntax rule = meta identifier, '=', definition list, ';';
  51 ;;
  52 ;; definition list = single definition, {'|', single definition};
  53 ;;
  54 ;; single definition = term, {',', term};
  55 ;;
  56 ;; term = factor, ['-', exception];
  57 ;;
  58 ;; exception = factor (* without <meta identifier> *);
  59 ;;
  60 ;; factor = [integer, '*'], primary;
  61 ;;
  62 ;; primary = optional sequence | repeated sequence | special sequence
  63 ;;         | grouped sequence | meta identifier | terminal string
  64 ;;         | empty;
  65 ;;
  66 ;; empty = ;
  67 ;;
  68 ;; optional sequence = '[', definition list, ']';
  69 ;;
  70 ;; repeated sequence = '{', definition list, '}';
  71 ;;
  72 ;; grouped sequence = '(', definition list, ')';
  73 ;;
  74 ;; terminal string = "'", character - "'", {character - "'"}, "'"
  75 ;;                 | '"', character - '"', {character - '"'}, '"';
  76 ;;
  77 ;; special sequence = '?', {character - '?'}, '?';
  78 ;;
  79 ;; meta identifier = letter, { letter | decimal digit | ' ' };
  80 ;;
  81 ;; integer = decimal digit, {decimal digit};
  82 ;;
  83 ;; comment = '(*', {comment symbol}, '*)';
  84 ;;
  85 ;; comment symbol = comment (* <== NESTED COMMENT *)
  86 ;;                | terminal string | special sequence | character;
  87 ;;
  88 ;; letter = ? A-Z a-z ?;
  89 ;;
  90 ;; decimal digit = ? 0-9 ?;
  91 ;;
  92 ;; character = letter | decimal digit
  93 ;;           | ',' | '=' | '|' | '/' | '!' | '*' | '(' | ')' | '[' | ']' | '{'
  94 ;;           | '}' | "'" | '"' | '?' | '-' | ';' | '.' | ' ' | ':' | '+' | '_'
  95 ;;           | '%' | '@' | '&' | '#' | '$' | '<' | '>' | '\' | '^' | '`' | '~';
  96 ;;
  97 ;;
  98 ;; There is also the following alternative representation:
  99 ;;
 100 ;; STANDARD   ALTERNATIVE
 101 ;;    |    ==>   / or !
 102 ;;    [    ==>   (/
 103 ;;    ]    ==>   /)
 104 ;;    {    ==>   (:
 105 ;;    }    ==>   :)
 106 ;;    ;    ==>   .
 107 ;;
 108 ;;
 109 ;; Differences Between ISO EBNF And ebnf2ps ISO EBNF
 110 ;; -------------------------------------------------
 111 ;;
 112 ;; ISO EBNF accepts the characters given by <character> production above,
 113 ;; HORIZONTAL TAB (^I), VERTICAL TAB (^K), NEWLINE (^J or ^M) and FORM FEED
 114 ;; (^L), any other characters are illegal.  But ebnf2ps accepts also the
 115 ;; european 8-bit accentuated characters (from \240 to \377).
 116 ;;
 117 ;;
 118 ;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 119
 120 ;;; code:
 121
 122
 123 (require 'ebnf-otz)
 124
 125
 126 (defvar ebnf-iso-lex nil
 127   "Value returned by `ebnf-iso-lex' function.")
 128
 129
 130 (defconst ebnf-no-meta-identifier nil)
 131
 132 \f
 133 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 134 ;; Syntatic analyzer
 135
 136
 137 ;;; ISO EBNF = syntax rule, {syntax rule};
 138
 139 (defun ebnf-iso-parser (start)
 140   "ISO EBNF parser."
 141   (let ((total (+ (- ebnf-limit start) 1))
 142         (bias (1- start))
 143         (origin (point))
 144         syntax-list token rule)
 145     (goto-char start)
 146     (setq token (ebnf-iso-lex))
 147     (and (eq token 'end-of-input)
 148          (error "Invalid ISO EBNF file format."))
 149     (while (not (eq token 'end-of-input))
 150       (ebnf-message-float
 151        "Parsing...%s%%"
 152        (/ (* (- (point) bias) 100.0) total))
 153       (setq token (ebnf-iso-syntax-rule token)
 154             rule  (cdr token)
 155             token (car token))
 156       (or (ebnf-add-empty-rule-list rule)
 157           (setq syntax-list (cons rule syntax-list))))
 158     (goto-char origin)
 159     syntax-list))
 160
 161
 162 ;;; syntax rule = meta identifier, '=', definition list, ';';
 163
 164 (defun ebnf-iso-syntax-rule (token)
 165   (let ((header ebnf-iso-lex)
 166         (action ebnf-action)
 167         body)
 168     (setq ebnf-action nil)
 169     (or (eq token 'non-terminal)
 170         (error "Invalid meta identifier syntax rule."))
 171     (or (eq (ebnf-iso-lex) 'equal)
 172         (error "Invalid syntax rule: missing `='."))
 173     (setq body (ebnf-iso-definition-list))
 174     (or (eq (car body) 'period)
 175         (error "Invalid syntax rule: missing `;' or `.'."))
 176     (setq body (cdr body))
 177     (ebnf-eps-add-production header)
 178     (cons (ebnf-iso-lex)
 179           (ebnf-make-production header body action))))
 180
 181
 182 ;;; definition list = single definition, {'|', single definition};
 183
 184 (defun ebnf-iso-definition-list ()
 185   (let (body sequence)
 186     (while (eq (car (setq sequence (ebnf-iso-single-definition)))
 187                'alternative)
 188       (setq sequence (cdr sequence)
 189             body     (cons sequence body)))
 190     (ebnf-token-alternative body sequence)))
 191
 192
 193 ;;; single definition = term, {',', term};
 194
 195 (defun ebnf-iso-single-definition ()
 196   (let (token seq term)
 197     (while (and (setq term  (ebnf-iso-term (ebnf-iso-lex))
 198                       token (car term)
 199                       term  (cdr term))
 200                 (eq token 'catenate))
 201       (setq seq (cons term seq)))
 202     (cons token
 203           (cond
 204            ;; null sequence
 205            ((null seq)
 206             term)
 207            ;; sequence with only one element
 208            ((and (null term) (= (length seq) 1))
 209             (car seq))
 210            ;; a real sequence
 211            (t
 212             (ebnf-make-sequence (nreverse (cons term seq))))
 213            ))))
 214
 215
 216 ;;; term = factor, ['-', exception];
 217 ;;;
 218 ;;; exception = factor (* without <meta identifier> *);
 219
 220 (defun ebnf-iso-term (token)
 221   (let ((factor (ebnf-iso-factor token)))
 222     (if (not (eq (car factor) 'except))
 223         ;; factor
 224         factor
 225       ;; factor - exception
 226       (let ((ebnf-no-meta-identifier t))
 227         (ebnf-token-except (cdr factor) (ebnf-iso-factor (ebnf-iso-lex)))))))
 228
 229
 230 ;;; factor = [integer, '*'], primary;
 231
 232 (defun ebnf-iso-factor (token)
 233   (if (eq token 'integer)
 234       (let ((times ebnf-iso-lex))
 235         (or (eq (ebnf-iso-lex) 'repeat)
 236             (error "Missing `*'."))
 237         (ebnf-token-repeat times (ebnf-iso-primary (ebnf-iso-lex))))
 238     (ebnf-iso-primary token)))
 239
 240
 241 ;;; primary = optional sequence | repeated sequence | special sequence
 242 ;;;         | grouped sequence | meta identifier | terminal string
 243 ;;;         | empty;
 244 ;;;
 245 ;;; empty = ;
 246 ;;;
 247 ;;; optional sequence = '[', definition list, ']';
 248 ;;;
 249 ;;; repeated sequence = '{', definition list, '}';
 250 ;;;
 251 ;;; grouped sequence = '(', definition list, ')';
 252 ;;;
 253 ;;; terminal string = "'", character - "'", {character - "'"}, "'"
 254 ;;;                 | '"', character - '"', {character - '"'}, '"';
 255 ;;;
 256 ;;; special sequence = '?', {character - '?'}, '?';
 257 ;;;
 258 ;;; meta identifier = letter, {letter | decimal digit};
 259
 260 (defun ebnf-iso-primary (token)
 261   (let ((primary
 262          (cond
 263           ;; terminal string
 264           ((eq token 'terminal)
 265            (ebnf-make-terminal ebnf-iso-lex))
 266           ;; meta identifier
 267           ((eq token 'non-terminal)
 268            (ebnf-make-non-terminal ebnf-iso-lex))
 269           ;; special sequence
 270           ((eq token 'special)
 271            (ebnf-make-special ebnf-iso-lex))
 272           ;; grouped sequence
 273           ((eq token 'begin-group)
 274            (let ((body (ebnf-iso-definition-list)))
 275              (or (eq (car body) 'end-group)
 276                  (error "Missing `)'."))
 277              (cdr body)))
 278           ;; optional sequence
 279           ((eq token 'begin-optional)
 280            (let ((body (ebnf-iso-definition-list)))
 281              (or (eq (car body) 'end-optional)
 282                  (error "Missing `]' or `/)'."))
 283              (ebnf-token-optional (cdr body))))
 284           ;; repeated sequence
 285           ((eq token 'begin-zero-or-more)
 286            (let* ((body   (ebnf-iso-definition-list))
 287                   (repeat (cdr body)))
 288              (or (eq (car body) 'end-zero-or-more)
 289                  (error "Missing `}' or `:)'."))
 290              (ebnf-make-zero-or-more repeat)))
 291           ;; empty
 292           (t
 293            nil)
 294           )))
 295     (cons (if primary
 296               (ebnf-iso-lex)
 297             token)
 298           primary)))
 299
 300 \f
 301 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 302 ;; Lexical analyzer
 303
 304
 305 (defconst ebnf-iso-token-table
 306   ;; control character & 8-bit character are set to `error'
 307   (let ((table (make-vector 256 'error))
 308         (char ?\040))
 309     ;; printable character
 310     (while (< char ?\060)
 311       (aset table char 'character)
 312       (setq char (1+ char)))
 313     ;; digits:
 314     (while (< char ?\072)
 315       (aset table char 'integer)
 316       (setq char (1+ char)))
 317     (while (< char ?\101)
 318       (aset table char 'character)
 319       (setq char (1+ char)))
 320     ;; upper case letters:
 321     (while (< char ?\133)
 322       (aset table char 'non-terminal)
 323       (setq char (1+ char)))
 324     (while (< char ?\141)
 325       (aset table char 'character)
 326       (setq char (1+ char)))
 327     ;; lower case letters:
 328     (while (< char ?\173)
 329       (aset table char 'non-terminal)
 330       (setq char (1+ char)))
 331     (while (< char ?\177)
 332       (aset table char 'character)
 333       (setq char (1+ char)))
 334     ;; European 8-bit accentuated characters:
 335     (setq char ?\240)
 336     (while (< char ?\400)
 337       (aset table char 'non-terminal)
 338       (setq char (1+ char)))
 339     ;; Override space characters:
 340     (aset table ?\013 'space)           ; [VT] vertical tab
 341     (aset table ?\n   'space)           ; [NL] linefeed
 342     (aset table ?\r   'space)           ; [CR] carriage return
 343     (aset table ?\t   'space)           ; [HT] horizontal tab
 344     (aset table ?\    'space)           ; [SP] space
 345     ;; Override form feed character:
 346     (aset table ?\f 'form-feed)         ; [FF] form feed
 347     ;; Override other lexical characters:
 348     (aset table ?\" 'double-terminal)
 349     (aset table ?\' 'single-terminal)
 350     (aset table ?\? 'special)
 351     (aset table ?*  'repeat)
 352     (aset table ?,  'catenate)
 353     (aset table ?-  'except)
 354     (aset table ?=  'equal)
 355     (aset table ?\) 'end-group)
 356     table)
 357   "Vector used to map characters to a lexical token.")
 358
 359
 360 (defun ebnf-iso-initialize ()
 361   "Initialize ISO EBNF token table."
 362   (if ebnf-iso-alternative-p
 363       ;; Override alternative lexical characters:
 364       (progn
 365         (aset ebnf-iso-token-table ?\( 'left-parenthesis)
 366         (aset ebnf-iso-token-table ?\[ 'character)
 367         (aset ebnf-iso-token-table ?\] 'character)
 368         (aset ebnf-iso-token-table ?\{ 'character)
 369         (aset ebnf-iso-token-table ?\} 'character)
 370         (aset ebnf-iso-token-table ?|  'character)
 371         (aset ebnf-iso-token-table ?\; 'character)
 372         (aset ebnf-iso-token-table ?/  'slash)
 373         (aset ebnf-iso-token-table ?!  'alternative)
 374         (aset ebnf-iso-token-table ?:  'colon)
 375         (aset ebnf-iso-token-table ?.  'period))
 376     ;; Override standard lexical characters:
 377     (aset ebnf-iso-token-table ?\( 'begin-parenthesis)
 378     (aset ebnf-iso-token-table ?\[ 'begin-optional)
 379     (aset ebnf-iso-token-table ?\] 'end-optional)
 380     (aset ebnf-iso-token-table ?\{ 'begin-zero-or-more)
 381     (aset ebnf-iso-token-table ?\} 'end-zero-or-more)
 382     (aset ebnf-iso-token-table ?|  'alternative)
 383     (aset ebnf-iso-token-table ?\; 'period)
 384     (aset ebnf-iso-token-table ?/  'character)
 385     (aset ebnf-iso-token-table ?!  'character)
 386     (aset ebnf-iso-token-table ?:  'character)
 387     (aset ebnf-iso-token-table ?.  'character)))
 388
 389
 390 (defun ebnf-iso-lex ()
 391   "Lexical analyser for ISO EBNF.
 392
 393 Return a lexical token.
 394
 395 See documentation for variable `ebnf-iso-lex'."
 396   (if (>= (point) ebnf-limit)
 397       'end-of-input
 398     (let (token)
 399       ;; skip spaces and comments
 400       (while (if (> (following-char) 255)
 401                  (progn
 402                    (setq token 'error)
 403                    nil)
 404                (setq token (aref ebnf-iso-token-table (following-char)))
 405                (cond
 406                 ((eq token 'space)
 407                  (skip-chars-forward " \013\n\r\t" ebnf-limit)
 408                  (< (point) ebnf-limit))
 409                 ((or (eq token 'begin-parenthesis)
 410                      (eq token 'left-parenthesis))
 411                  (forward-char)
 412                  (if (/= (following-char) ?*)
 413                      ;; no comment
 414                      nil
 415                    ;; comment
 416                    (ebnf-iso-skip-comment)
 417                    t))
 418                 ((eq token 'form-feed)
 419                  (forward-char)
 420                  (setq ebnf-action 'form-feed))
 421                 (t nil)
 422                 )))
 423       (cond
 424        ;; end of input
 425        ((>= (point) ebnf-limit)
 426         'end-of-input)
 427        ;; error
 428        ((eq token 'error)
 429         (error "Illegal character."))
 430        ;; integer
 431        ((eq token 'integer)
 432         (setq ebnf-iso-lex (ebnf-buffer-substring "0-9"))
 433         'integer)
 434        ;; special: ?special?
 435        ((eq token 'special)
 436         (setq ebnf-iso-lex (concat "?"
 437                                    (ebnf-string " ->@-~" ?\? "special")
 438                                    "?"))
 439         'special)
 440        ;; terminal: "string"
 441        ((eq token 'double-terminal)
 442         (setq ebnf-iso-lex (ebnf-string " !#-~" ?\" "terminal"))
 443         'terminal)
 444        ;; terminal: 'string'
 445        ((eq token 'single-terminal)
 446         (setq ebnf-iso-lex (ebnf-string " -&(-~" ?\' "terminal"))
 447         'terminal)
 448        ;; non-terminal
 449        ((eq token 'non-terminal)
 450         (setq ebnf-iso-lex (ebnf-iso-normalize
 451                             (ebnf-trim-right
 452                              (ebnf-buffer-substring " 0-9A-Za-z\240-\377"))))
 453         (and ebnf-no-meta-identifier
 454              (error "Exception sequence should not contain a meta identifier."))
 455         'non-terminal)
 456        ;; begin optional, begin list or begin group
 457        ((eq token 'left-parenthesis)
 458         (forward-char)
 459         (cond ((= (following-char) ?/)
 460                (forward-char)
 461                'begin-optional)
 462               ((= (following-char) ?:)
 463                (forward-char)
 464                'begin-zero-or-more)
 465               (t
 466                'begin-group)
 467               ))
 468        ;; end optional or alternative
 469        ((eq token 'slash)
 470         (forward-char)
 471         (if (/= (following-char) ?\))
 472             'alternative
 473           (forward-char)
 474           'end-optional))
 475        ;; end list
 476        ((eq token 'colon)
 477         (forward-char)
 478         (if (/= (following-char) ?\))
 479             'character
 480           (forward-char)
 481           'end-zero-or-more))
 482        ;; begin group
 483        ((eq token 'begin-parenthesis)
 484         'begin-group)
 485        ;; miscellaneous
 486        (t
 487         (forward-char)
 488         token)
 489        ))))
 490
 491
 492 (defconst ebnf-iso-comment-chars "^*(\000-\010\016-\037\177-\237")
 493
 494
 495 (defun ebnf-iso-skip-comment ()
 496   (forward-char)
 497   (cond
 498    ;; open EPS file
 499    ((and ebnf-eps-executing (= (following-char) ?\[))
 500     (ebnf-eps-add-context (ebnf-iso-eps-filename)))
 501    ;; close EPS file
 502    ((and ebnf-eps-executing (= (following-char) ?\]))
 503     (ebnf-eps-remove-context (ebnf-iso-eps-filename)))
 504    ;; any other action in comment
 505    (t
 506     (setq ebnf-action (aref ebnf-comment-table (following-char))))
 507    )
 508   (let ((pair 1))
 509     (while (> pair 0)
 510       (skip-chars-forward ebnf-iso-comment-chars ebnf-limit)
 511       (cond ((>= (point) ebnf-limit)
 512              (error "Missing end of comment: `*)'."))
 513             ((= (following-char) ?*)
 514              (skip-chars-forward "*" ebnf-limit)
 515              (when (= (following-char) ?\))
 516                ;; end of comment
 517                (forward-char)
 518                (setq pair (1- pair))))
 519             ((= (following-char) ?\()
 520              (skip-chars-forward "(" ebnf-limit)
 521              (when (= (following-char) ?*)
 522                ;; beginning of comment
 523                (forward-char)
 524                (setq pair (1+ pair))))
 525             (t
 526              (error "Illegal character."))
 527             ))))
 528
 529
 530 (defun ebnf-iso-eps-filename ()
 531   (forward-char)
 532   (buffer-substring-no-properties
 533    (point)
 534    (let ((chars (concat ebnf-iso-comment-chars "\n"))
 535          found)
 536      (while (not found)
 537        (skip-chars-forward chars ebnf-limit)
 538        (setq found
 539              (cond ((>= (point) ebnf-limit)
 540                     (point))
 541                    ((= (following-char) ?*)
 542                     (skip-chars-forward "*" ebnf-limit)
 543                     (if (/= (following-char) ?\))
 544                         nil
 545                       (backward-char)
 546                       (point)))
 547                    ((= (following-char) ?\()
 548                     (forward-char)
 549                     (if (/= (following-char) ?*)
 550                         nil
 551                       (backward-char)
 552                       (point)))
 553                    (t
 554                     (point))
 555                    )))
 556      found)))
 557
 558
 559 (defun ebnf-iso-normalize (str)
 560   (if (not ebnf-iso-normalize-p)
 561       str
 562     (let ((len (length str))
 563           (stri 0)
 564           (spaces 0))
 565       ;; count exceeding spaces
 566       (while (< stri len)
 567         (if (/= (aref str stri) ?\ )
 568             (setq stri (1+ stri))
 569           (setq stri (1+ stri))
 570           (while (and (< stri len) (= (aref str stri) ?\ ))
 571             (setq stri   (1+ stri)
 572                   spaces (1+ spaces)))))
 573       (if (zerop spaces)
 574           ;; no exceeding space
 575           str
 576         ;; at least one exceeding space
 577         (let ((new (make-string (- len spaces) ?\ ))
 578               (newi 0))
 579           ;; eliminate exceeding spaces
 580           (setq stri 0)
 581           (while (> spaces 0)
 582             (if (/= (aref str stri) ?\ )
 583                 (progn
 584                   (aset new newi (aref str stri))
 585                   (setq stri (1+ stri)
 586                         newi (1+ newi)))
 587               (aset new newi (aref str stri))
 588               (setq stri (1+ stri)
 589                     newi (1+ newi))
 590               (while (and (> spaces 0) (= (aref str stri) ?\ ))
 591                 (setq stri   (1+ stri)
 592                       spaces (1- spaces)))))
 593           ;; remaining is normalized
 594           (while (< stri len)
 595             (aset new newi (aref str stri))
 596             (setq stri (1+ stri)
 597                   newi (1+ newi)))
 598           new)))))
 599
 600 \f
 601 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 602
 603
 604 (provide 'ebnf-iso)
 605
 606
 607 ;;; ebnf-iso.el ends here