emacs/lisp/progmodes/ebnf-iso.el

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;;; ebnf-iso.el --- parser for ISO EBNF -*- lexical-binding: t; -*-
;; Copyright (C) 1999-2024 Free Software Foundation, Inc.
;; Author: Vinicius Jose Latorre <viniciusjl.gnu@gmail.com>
;; Keywords: text, ebnf, PostScript
;; Old-Version: 1.9
;; 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 <https://www.gnu.org/licenses/>.
;;; Commentary:
;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;;
;; This is part of ebnf2ps package.
;;
;; This package defines a parser for ISO EBNF.
;;
;; See ebnf2ps.el for documentation.
;;
;;
;; ISO EBNF Syntax
;; ---------------
;;
;; See the URL:
;; `https://www.cl.cam.ac.uk/~mgk25/iso-ebnf.html'
;; ("International Standard of the ISO EBNF Notation").
;;
;;
;; ISO EBNF = syntax rule, {syntax rule};
;;
;; syntax rule = meta identifier, '=', definition list, ';';
;;
;; definition list = single definition, {'|', single definition};
;;
;; single definition = term, {',', term};
;;
;; term = factor, ['-', exception];
;;
;; exception = factor (* without <meta identifier> *);
;;
;; factor = [integer, '*'], primary;
;;
;; primary = optional sequence | repeated sequence | special sequence
;; | grouped sequence | meta identifier | terminal string
;; | empty;
;;
;; empty = ;
;;
;; optional sequence = '[', definition list, ']';
;;
;; repeated sequence = '{', definition list, '}';
;;
;; grouped sequence = '(', definition list, ')';
;;
;; terminal string = "'", character - "'", {character - "'"}, "'"
;; | '"', character - '"', {character - '"'}, '"';
;;
;; special sequence = '?', {character - '?'}, '?';
;;
;; meta identifier = letter, { letter | decimal digit | ' ' };
;;
;; integer = decimal digit, {decimal digit};
;;
;; comment = '(*', {comment symbol}, '*)';
;;
;; comment symbol = comment (* <== NESTED COMMENT *)
;; | terminal string | special sequence | character;
;;
;; letter = ? A-Z a-z ?;
;;
;; decimal digit = ? 0-9 ?;
;;
;; character = letter | decimal digit
;; | ',' | '=' | '|' | '/' | '!' | '*' | '(' | ')' | '[' | ']' | '{'
;; | '}' | "'" | '"' | '?' | '-' | ';' | '.' | ' ' | ':' | '+' | '_'
;; | '%' | '@' | '&' | '#' | '$' | '<' | '>' | '\' | '^' | '`' | '~';
;;
;;
;; There is also the following alternative representation:
;;
;; STANDARD ALTERNATIVE
;; | ==> / or !
;; [ ==> (/
;; ] ==> /)
;; { ==> (:
;; } ==> :)
;; ; ==> .
;;
;;
;; Differences Between ISO EBNF And ebnf2ps ISO EBNF
;; -------------------------------------------------
;;
;; ISO EBNF accepts the characters given by <character> production above,
;; HORIZONTAL TAB (^I), VERTICAL TAB (^K), NEWLINE (^J or ^M) and FORM FEED
;; (^L), any other characters are invalid. But ebnf2ps accepts also the
;; european 8-bit accentuated characters (from \240 to \377) and underscore
;; (_).
;;
;;
;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Code:
(require 'ebnf-otz)
(defvar ebnf-iso-lex nil
"Value returned by `ebnf-iso-lex' function.")
(defvar ebnf-no-meta-identifier nil
"Used by `ebnf-iso-term' and `ebnf-iso-lex' functions.")
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Syntactic analyzer
;;; ISO EBNF = syntax rule, {syntax rule};
(defun ebnf-iso-parser (start)
"ISO EBNF parser."
(let ((total (+ (- ebnf-limit start) 1))
(bias (1- start))
(origin (point))
syntax-list token rule)
(goto-char start)
(setq token (ebnf-iso-lex))
(and (eq token 'end-of-input)
(error "Invalid ISO EBNF file format"))
(while (not (eq token 'end-of-input))
(ebnf-message-float
"Parsing...%s%%"
(/ (* (- (point) bias) 100.0) total))
(setq token (ebnf-iso-syntax-rule token)
rule (cdr token)
token (car token))
(or (ebnf-add-empty-rule-list rule)
(setq syntax-list (cons rule syntax-list))))
(goto-char origin)
syntax-list))
;;; syntax rule = meta identifier, '=', definition list, ';';
(defun ebnf-iso-syntax-rule (token)
(let ((header ebnf-iso-lex)
(action ebnf-action)
body)
(setq ebnf-action nil)
(or (eq token 'non-terminal)
(error "Invalid meta identifier syntax rule"))
(or (eq (ebnf-iso-lex) 'equal)
(error "Invalid syntax rule: missing `='"))
(setq body (ebnf-iso-definition-list))
(or (eq (car body) 'period)
(error "Invalid syntax rule: missing `;' or `.'"))
(setq body (cdr body))
(ebnf-eps-add-production header)
(cons (ebnf-iso-lex)
(ebnf-make-production header body action))))
;;; definition list = single definition, {'|', single definition};
(defun ebnf-iso-definition-list ()
(let (body sequence)
(while (eq (car (setq sequence (ebnf-iso-single-definition)))
'alternative)
(setq sequence (cdr sequence)
body (cons sequence body)))
(ebnf-token-alternative body sequence)))
;;; single definition = term, {',', term};
(defun ebnf-iso-single-definition ()
(let (token seq term)
(while (and (setq term (ebnf-iso-term (ebnf-iso-lex))
token (car term)
term (cdr term))
(eq token 'catenate))
(setq seq (cons term seq)))
(cons token
(ebnf-token-sequence (if term
(cons term seq)
seq)))))
;;; term = factor, ['-', exception];
;;;
;;; exception = factor (* without <meta identifier> *);
(defun ebnf-iso-term (token)
(let ((factor (ebnf-iso-factor token)))
(if (not (eq (car factor) 'except))
;; factor
factor
;; factor - exception
(let ((ebnf-no-meta-identifier t))
(ebnf-token-except (cdr factor) (ebnf-iso-factor (ebnf-iso-lex)))))))
;;; factor = [integer, '*'], primary;
(defun ebnf-iso-factor (token)
(if (eq token 'integer)
(let ((times ebnf-iso-lex))
(or (eq (ebnf-iso-lex) 'repeat)
(error "Missing `*'"))
(ebnf-token-repeat times (ebnf-iso-primary (ebnf-iso-lex))))
(ebnf-iso-primary token)))
;;; primary = optional sequence | repeated sequence | special sequence
;;; | grouped sequence | meta identifier | terminal string
;;; | empty;
;;;
;;; empty = ;
;;;
;;; optional sequence = '[', definition list, ']';
;;;
;;; repeated sequence = '{', definition list, '}';
;;;
;;; grouped sequence = '(', definition list, ')';
;;;
;;; terminal string = "'", character - "'", {character - "'"}, "'"
;;; | '"', character - '"', {character - '"'}, '"';
;;;
;;; special sequence = '?', {character - '?'}, '?';
;;;
;;; meta identifier = letter, {letter | decimal digit};
(defun ebnf-iso-primary (token)
(let ((primary
(cond
;; terminal string
((eq token 'terminal)
(ebnf-make-terminal ebnf-iso-lex))
;; meta identifier
((eq token 'non-terminal)
(ebnf-make-non-terminal ebnf-iso-lex))
;; special sequence
((eq token 'special)
(ebnf-make-special ebnf-iso-lex))
;; grouped sequence
((eq token 'begin-group)
(let ((body (ebnf-iso-definition-list)))
(or (eq (car body) 'end-group)
(error "Missing `)'"))
(cdr body)))
;; optional sequence
((eq token 'begin-optional)
(let ((body (ebnf-iso-definition-list)))
(or (eq (car body) 'end-optional)
(error "Missing `]' or `/)'"))
(ebnf-token-optional (cdr body))))
;; repeated sequence
((eq token 'begin-zero-or-more)
(let* ((body (ebnf-iso-definition-list))
(repeat (cdr body)))
(or (eq (car body) 'end-zero-or-more)
(error "Missing `}' or `:)'"))
(ebnf-make-zero-or-more repeat)))
;; empty
(t
nil)
)))
(cons (if primary
(ebnf-iso-lex)
token)
primary)))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Lexical analyzer
(defconst ebnf-iso-token-table
;; control character & 8-bit character are set to `error'
(let ((table (make-vector 256 'error))
(char ?\040))
;; printable character
(while (< char ?\060)
(aset table char 'character)
(setq char (1+ char)))
;; digits:
(while (< char ?\072)
(aset table char 'integer)
(setq char (1+ char)))
(while (< char ?\101)
(aset table char 'character)
(setq char (1+ char)))
;; upper case letters:
(while (< char ?\133)
(aset table char 'non-terminal)
(setq char (1+ char)))
(while (< char ?\141)
(aset table char 'character)
(setq char (1+ char)))
;; lower case letters:
(while (< char ?\173)
(aset table char 'non-terminal)
(setq char (1+ char)))
(while (< char ?\177)
(aset table char 'character)
(setq char (1+ char)))
;; European 8-bit accentuated characters:
(setq char ?\240)
(while (< char ?\400)
(aset table char 'non-terminal)
(setq char (1+ char)))
;; Override space characters:
(aset table ?\013 'space) ; [VT] vertical tab
(aset table ?\n 'space) ; [NL] linefeed
(aset table ?\r 'space) ; [CR] carriage return
(aset table ?\t 'space) ; [HT] horizontal tab
(aset table ?\ 'space) ; [SP] space
;; Override form feed character:
(aset table ?\f 'form-feed) ; [FF] form feed
;; Override other lexical characters:
(aset table ?_ 'non-terminal)
(aset table ?\" 'double-terminal)
(aset table ?\' 'single-terminal)
(aset table ?\? 'special)
(aset table ?* 'repeat)
(aset table ?, 'catenate)
(aset table ?- 'except)
(aset table ?= 'equal)
(aset table ?\) 'end-group)
table)
"Vector used to map characters to a lexical token.")
(defun ebnf-iso-initialize ()
"Initialize ISO EBNF token table."
(if ebnf-iso-alternative-p
;; Override alternative lexical characters:
(progn
(aset ebnf-iso-token-table ?\( 'left-parenthesis)
(aset ebnf-iso-token-table ?\[ 'character)
(aset ebnf-iso-token-table ?\] 'character)
(aset ebnf-iso-token-table ?\{ 'character)
(aset ebnf-iso-token-table ?\} 'character)
(aset ebnf-iso-token-table ?| 'character)
(aset ebnf-iso-token-table ?\; 'character)
(aset ebnf-iso-token-table ?/ 'slash)
(aset ebnf-iso-token-table ?! 'alternative)
(aset ebnf-iso-token-table ?: 'colon)
(aset ebnf-iso-token-table ?. 'period))
;; Override standard lexical characters:
(aset ebnf-iso-token-table ?\( 'begin-parenthesis)
(aset ebnf-iso-token-table ?\[ 'begin-optional)
(aset ebnf-iso-token-table ?\] 'end-optional)
(aset ebnf-iso-token-table ?\{ 'begin-zero-or-more)
(aset ebnf-iso-token-table ?\} 'end-zero-or-more)
(aset ebnf-iso-token-table ?| 'alternative)
(aset ebnf-iso-token-table ?\; 'period)
(aset ebnf-iso-token-table ?/ 'character)
(aset ebnf-iso-token-table ?! 'character)
(aset ebnf-iso-token-table ?: 'character)
(aset ebnf-iso-token-table ?. 'character)))
(defconst ebnf-iso-non-terminal-chars
" 0-9A-Za-z_\u00a0-\u00ff")
(defun ebnf-iso-lex ()
"Lexical analyzer for ISO EBNF.
Return a lexical token.
See documentation for variable `ebnf-iso-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-iso-token-table (following-char)))
(cond
((eq token 'space)
(skip-chars-forward " \013\n\r\t" ebnf-limit)
(< (point) ebnf-limit))
((or (eq token 'begin-parenthesis)
(eq token 'left-parenthesis))
(forward-char)
(if (/= (following-char) ?*)
;; no comment
nil
;; comment
(ebnf-iso-skip-comment)
t))
((eq token 'form-feed)
(forward-char)
(setq ebnf-action 'form-feed))
(t nil)
)))
(cond
;; end of input
((>= (point) ebnf-limit)
'end-of-input)
;; error
((eq token 'error)
(error "Invalid character"))
;; integer
((eq token 'integer)
(setq ebnf-iso-lex (ebnf-buffer-substring "0-9"))
'integer)
;; special: ?special?
((eq token 'special)
(setq ebnf-iso-lex (concat (and ebnf-special-show-delimiter "?")
(ebnf-string " ->@-~" ?\? "special")
(and ebnf-special-show-delimiter "?")))
'special)
;; terminal: "string"
((eq token 'double-terminal)
(setq ebnf-iso-lex (ebnf-string " !#-~" ?\" "terminal"))
'terminal)
;; terminal: 'string'
((eq token 'single-terminal)
(setq ebnf-iso-lex (ebnf-string " -&(-~" ?\' "terminal"))
'terminal)
;; non-terminal
((eq token 'non-terminal)
(setq ebnf-iso-lex
(ebnf-iso-normalize
(ebnf-trim-right
(ebnf-buffer-substring ebnf-iso-non-terminal-chars))))
(and ebnf-no-meta-identifier
(error "Exception sequence should not contain a meta identifier"))
'non-terminal)
;; begin optional, begin list or begin group
((eq token 'left-parenthesis)
(forward-char)
(cond ((= (following-char) ?/)
(forward-char)
'begin-optional)
((= (following-char) ?:)
(forward-char)
'begin-zero-or-more)
(t
'begin-group)
))
;; end optional or alternative
((eq token 'slash)
(forward-char)
(if (/= (following-char) ?\))
'alternative
(forward-char)
'end-optional))
;; end list
((eq token 'colon)
(forward-char)
(if (/= (following-char) ?\))
'character
(forward-char)
'end-zero-or-more))
;; begin group
((eq token 'begin-parenthesis)
'begin-group)
;; miscellaneous
(t
(forward-char)
token)
))))
(defconst ebnf-iso-comment-chars
"^*(\000-\010\016-\037\177\u0080-\u009f")
(defun ebnf-iso-skip-comment ()
(forward-char)
(cond
;; open EPS file
((and ebnf-eps-executing (= (following-char) ?\[))
(ebnf-eps-add-context (ebnf-iso-eps-filename)))
;; close EPS file
((and ebnf-eps-executing (= (following-char) ?\]))
(ebnf-eps-remove-context (ebnf-iso-eps-filename)))
;; EPS header
((and ebnf-eps-executing (= (following-char) ?H))
(ebnf-eps-header-comment (ebnf-iso-eps-filename)))
;; EPS footer
((and ebnf-eps-executing (= (following-char) ?F))
(ebnf-eps-footer-comment (ebnf-iso-eps-filename)))
;; any other action in comment
(t
(setq ebnf-action (aref ebnf-comment-table (following-char))))
)
(let ((pair 1))
(while (> pair 0)
(skip-chars-forward ebnf-iso-comment-chars ebnf-limit)
(cond ((>= (point) ebnf-limit)
(error "Missing end of comment: `*)'"))
((= (following-char) ?*)
(skip-chars-forward "*" ebnf-limit)
(when (= (following-char) ?\))
;; end of comment
(forward-char)
(setq pair (1- pair))))
((= (following-char) ?\()
(skip-chars-forward "(" ebnf-limit)
(when (= (following-char) ?*)
;; beginning of comment
(forward-char)
(setq pair (1+ pair))))
(t
(error "Invalid character"))
))))
(defun ebnf-iso-eps-filename ()
(forward-char)
(buffer-substring-no-properties
(point)
(let ((chars (concat ebnf-iso-comment-chars "\n"))
found)
(while (not found)
(skip-chars-forward chars ebnf-limit)
(setq found
(cond ((>= (point) ebnf-limit)
(point))
((= (following-char) ?*)
(skip-chars-forward "*" ebnf-limit)
(if (/= (following-char) ?\))
nil
(backward-char)
(point)))
((= (following-char) ?\()
(forward-char)
(if (/= (following-char) ?*)
nil
(backward-char)
(point)))
(t
(point))
)))
found)))
(defun ebnf-iso-normalize (str)
(if (not ebnf-iso-normalize-p)
str
(let ((len (length str))
(stri 0)
(spaces 0))
;; count exceeding spaces
(while (< stri len)
(if (/= (aref str stri) ?\ )
(setq stri (1+ stri))
(setq stri (1+ stri))
(while (and (< stri len) (= (aref str stri) ?\ ))
(setq stri (1+ stri)
spaces (1+ spaces)))))
(if (zerop spaces)
;; no exceeding space
str
;; at least one exceeding space
(let ((new (make-string (- len spaces) ?\ ))
(newi 0))
;; eliminate exceeding spaces
(setq stri 0)
(while (> spaces 0)
(if (/= (aref str stri) ?\ )
(progn
(aset new newi (aref str stri))
(setq stri (1+ stri)
newi (1+ newi)))
(aset new newi (aref str stri))
(setq stri (1+ stri)
newi (1+ newi))
(while (and (> spaces 0) (= (aref str stri) ?\ ))
(setq stri (1+ stri)
spaces (1- spaces)))))
;; remaining is normalized
(while (< stri len)
(aset new newi (aref str stri))
(setq stri (1+ stri)
newi (1+ newi)))
new)))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(provide 'ebnf-iso)
;;; ebnf-iso.el ends here