Function: ebnf-bnf-lex

ebnf-bnf-lex is a byte-compiled function defined in ebnf-bnf.el.gz.

Signature

(ebnf-bnf-lex)

Documentation

Lexical analyzer for EBNF.

Return a lexical token.

See documentation for variable ebnf-bnf-lex(var)/ebnf-bnf-lex(fun).

Source Code

;; Defined in /usr/src/emacs/lisp/progmodes/ebnf-bnf.el.gz
(defun ebnf-bnf-lex ()
  "Lexical analyzer for EBNF.

Return a lexical token.

See documentation for variable `ebnf-bnf-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-bnf-token-table (following-char)))
	       (cond
		((eq token 'space)
		 (skip-chars-forward " \013\n\r\t" ebnf-limit)
		 (< (point) ebnf-limit))
		((eq token 'comment)
		 (ebnf-bnf-skip-comment))
		((eq token 'form-feed)
		 (forward-char)
		 (setq ebnf-action 'form-feed))
		(t nil)
		)))
      (setq ebnf-default-p nil)
      (cond
       ;; end of input
       ((>= (point) ebnf-limit)
	'end-of-input)
       ;; error
       ((eq token 'error)
	(error "Invalid character"))
       ;; default
       ((eq token 'default)
	(forward-char)
	(if (memq (aref ebnf-bnf-token-table (following-char))
		  '(terminal non-terminal special))
	    (prog1
		(ebnf-bnf-lex)
	      (setq ebnf-default-p t))
	  (error "Invalid `default' element")))
       ;; integer
       ((eq token 'integer)
	(setq ebnf-bnf-lex (ebnf-buffer-substring "0-9"))
	'integer)
       ;; special: ?special?
       ((eq token 'special)
	(setq ebnf-bnf-lex (concat (and ebnf-special-show-delimiter "?")
				   (ebnf-string " ->@-~" ?\? "special")
				   (and ebnf-special-show-delimiter "?")))
	'special)
       ;; terminal: "string"
       ((eq token 'terminal)
	(setq ebnf-bnf-lex (ebnf-unescape-string (ebnf-get-string)))
	'terminal)
       ;; non-terminal or terminal
       ((eq token 'non-terminal)
	(setq ebnf-bnf-lex (ebnf-buffer-substring ebnf-bnf-non-terminal-chars))
	(let ((case-fold-search ebnf-case-fold-search)
	      match)
	  (if (and ebnf-terminal-regexp
		   (setq match (string-match ebnf-terminal-regexp
					     ebnf-bnf-lex))
		   (zerop match)
		   (= (match-end 0) (length ebnf-bnf-lex)))
	      'terminal
	    'non-terminal)))
       ;; end of list: }+, }*, }
       ((eq token 'end-list)
	(forward-char)
	(cond
	 ((= (following-char) ?+)
	  (forward-char)
	  'end-one-or-more)
	 ((= (following-char) ?*)
	  (forward-char)
	  'end-zero-or-more)
	 (t
	  'end-zero-or-more)
	 ))
       ;; alternative: |, ||
       ((eq token 'alternative)
	(forward-char)
	(if (/= (following-char) ?|)
	    'alternative
	  (forward-char)
	  'list-separator))
       ;; miscellaneous: {, (, ), [, ], ., =, /, +, -, *
       (t
	(forward-char)
	token)
       ))))