lilypond-mode

lilypond-what-beat.el (8199B)

---

 ;; Features:
 ;;
 ;; -> Counts number of notes between last | and point. Adds durations of
 ;; each note up, and returns result.
 ;;
 ;; -> Works well on notes and chords.
 ;;
 ;; -> Ignores most keywords, like \override
 ;;
 ;; -> Is aware of certain keywords which often contain parameters that
 ;; look like notes, but should not be counted.
 ;;  | a \key b \minor c    % b is not counted, but a and c are.
 ;;
 ;; -> Ignores Scheme expressions, which start with #
 ;;
 ;; -> Doesn't ignore the \times keyword. Intelligently handles triplets.
 ;;
 ;;
 ;; Caveats:
 ;;
 ;; -> Doesn't work on regions that aren't preceded by a |. This is because such
 ;; notes are only delimited by a {, and what-beat can't distinguish a { that
 ;; opens a set of notes from an internal { (say from a triplet)
 ;;
 ;; -> Doesn't work with << >>  expressions or nested {} expressions (unless
 ;; {} is part of a keyword like \times)
 ;;
 ;; -> Keywords abutted against a note are not visible to what-beat, and
 ;; can therefore surreptitiosly sneak fake notes into what-beat.
 ;; | c\glissando f       <- BAD:  the f gets counted, but shouldn't
 ;; | c \glissando f      <- GOOD: the f gets ignored
 ;;
 ;; -> Does not look outside notes context. Derivation rules don't work:
 ;; str = \notes { a8 b c d }
 ;; \score { \notes { | e4 %{ gets counted }% \str %{gets ignored}%
 ;;
 ;; -> Does not handle repeats.
 ;;
 ;; -> Ignores \bar commands (and does not get confused by a | inside a \bar)
 ;;
 
 ;; Recognizes pitch & octave
 (setq pitch-regex "\\([a-z]+[,']*\\|<[^>]*>\\)\\(=[,']*\\)?")
 ;; Recognizes duration
 (setq duration-regex "[ \t\n]*\\(\\(\\(128\\|6?4\\|3?2\\|16?\\|8\\)\\([.]*\\)\\)\\([ \t]*[*][ \t]*\\([0-9]+\\)\\(/\\([1-9][0-9]*\\)\\)?\\)?\\)")
 
 ;; These keywords precede notes that should not be counted during beats
 (setq Parm-Keywords '("key" "clef" "appoggiatura" "acciaccatura" "grace"
 		      "override" "revert" "glissando"))
 
 
 (defun extract-match (string match-num)
   (if (null (match-beginning match-num))
       nil
     (substring string (match-beginning match-num) (match-end match-num))))
 
 
 (defun add-fractions (f1 f2)
   "Adds two fractions, both are (numerator denominator)"
   (setq result (list (+ (* (car f1) (cadr f2)) (* (car f2) (cadr f1)))
 		     (* (cadr f1) (cadr f2))))
   (setq result (reduce-fraction result 2))
   (setq result (reduce-fraction result 3))
   (setq result (reduce-fraction result 5))
   (setq result (reduce-fraction result 7)))
 
 
 (defun reduce-fraction (f divisor)
   "Eliminates divisor from fraction if present"
   (while (and (= 0 (% (car result) divisor))
 	      (= 0 (% (cadr result) divisor))
 	      (< 1 (cadr result))
 	      (< 0 (car result)))
     (setq result (list (/ (car result) divisor) (/ (cadr result) divisor))))
   result)
 
 
 (defun parse-duration (duration)
   "Returns a duration string parsed as '(numerator denominator)"
   (string-match duration-regex duration)
   (let ((result (list 1 (string-to-number (extract-match duration 2))))
 	(dots (extract-match duration 4))
 	(numerator (or (extract-match duration 6) "1"))
 	(denominator (or (extract-match duration 8) "1")))
     (if (and (not (null dots)) (< 0 (string-width dots)))
 	(dotimes (dummy (string-width dots))
 	  (setq result (list (1+ (* 2 (car result))) (* 2 (cadr result))))))
     (list (* (string-to-number numerator) (car result))
 	  (* (string-to-number denominator) (cadr result)))
     ))
 
 (defun walk-note-duration ()
   "Returns duration of next note, moving point past note.
 If point is not before a note, returns nil
 If next note has no duration, returns t"
   (let ((have-pitch (looking-at pitch-regex)))
     (if have-pitch (goto-char (match-end 0)))
     (if (not (looking-at duration-regex))
 	have-pitch
       (goto-char (match-end 0))
       (parse-duration (match-string 0)))))
 
 					; returns nil if not at a comment
 (defun skip-comment ()
   (if (not (char-equal ?\% (following-char)))
       nil
     (progn
       (forward-char)
       (if (char-equal ?\{ (following-char))
 	  (re-search-forward "}%" nil t)
 	(progn
 	  (skip-chars-forward "^\n")
 	  (forward-char)))
       t
       )))
 
 					; returns nil if not at a quotation
 (defun skip-quotation ()
   (if (not (char-equal ?\" (following-char)))
       nil
     (progn
       (forward-char)
       (skip-chars-forward "^\"")
       (forward-char)
       t
       )))
 
 					; returns nil if not at a sexp
 (defun skip-sexp ()
   (interactive)
   (if (not (char-equal ?\# (following-char)))
       nil
     (progn
       (forward-char)
       (if (char-equal ?\' (following-char))
 	  (forward-char))
       (if (not (char-equal ?\( (following-char)))
 	  (skip-chars-forward "^ \t\n")
 	(progn
 	  (let ((paren 1))
 	    (while (< 0 paren)
 	      (forward-char)
 	      (cond ((char-equal ?\( (following-char))
 		     (setq paren (1+ paren)))
 		    ((char-equal ?\) (following-char))
 		     (setq paren (1- paren)))))
 	    (forward-char)
 	    t
 	    ))))))
 
 (defun goto-note-begin ()
   (interactive)
 					; skip anything that is not ws. And skip any comments or quotations
   (while (or (< 0 (skip-chars-forward "^ \t\n~%#\""))
 	     (skip-comment)
 	     (skip-quotation)
 	     (skip-sexp)))
 					; Now skip anything that isn't alphanum or \. And skip comments or quotations
   (while (or (< 0 (skip-chars-forward "^A-Za-z1-9<%}#=\""))
 	     (skip-comment)
 	     (skip-quotation)
 	     (skip-sexp)))
 					; (skip-chars-forward "^\\") Why doesn't this work?!!
   (if (char-equal ?\\ (preceding-char))
       (backward-char))
   )
 
 
 (defun skip-good-keywords ()
   (if (looking-at "\\\\\\([a-z]*\\)")
       (progn
 	(goto-char (match-end 0))
 	(if (member (match-string 1) Parm-Keywords)
 	    (progn
 	      (if (looking-at "[ \t\n]*?\\([a-z0-9_]+\\|{[^}]*}\\|\"[^\"]*\"\\)")
 		  (goto-char (match-end 0))
 		(error "Improper regex match:")
 		(error "Unknown text: %s")
 		))))))
 
 (defun find-measure-start ()
   (let ((start (re-search-backward "\|" 0 t)))
     (if (null start)
 	-1
       (if (looking-at "[^ \n\t]*\"")
 	  (find-measure-start)
 	(point)
 	))))
 
 (defun get-beat ()
   (save-excursion
     (save-restriction
       (let* ((end (point))
 	     (measure-start (find-measure-start))
 	     (last-dur (or (re-search-backward duration-regex 0 t) -1))
 	     (duration (if (= -1 last-dur) 0 (parse-duration (match-string 0))))
 	     (result '(0 1)))		; 0 in fraction form
 	(if (= measure-start -1)
 	    (message "No | before point")
 	  (goto-char (1+ measure-start))
 	  (goto-note-begin)
 	  (while (< (point) end)
 	    (let ((new-duration (walk-note-duration)))
 	      (if (null new-duration)
 		  (if (not (looking-at
 			    (concat "\\\\t\\(?:\\(imes\\)\\|uplet\\)[ \t]*\\([0-9]+\\)/\\([0-9]+\\)\\(?:[ \t\n]"
 				    duration-regex "\\)?[ \t\n]*{")))
 		      (skip-good-keywords)
 
 					; handle \times/\tuplet specially
 		    (let* ((times-p (match-beginning 1))
 			   (numerator (string-to-number (match-string (if times-p 2 3))))
 			   (denominator (string-to-number (match-string (if times-p 3 2)))))
 		      (goto-char (match-end 0))
 		      (goto-note-begin)
 		      (while (and (not (looking-at "}"))
 				  (< (point) end))
 			(setq new-duration (walk-note-duration))
 			(if (null new-duration)
 			    (if (looking-at "\\\\[a-z]*[ \t]*[a-z]*")
 				(goto-char (match-end 0))
 			      (error "Unknown text: %S %s" result(buffer-substring (point) end))))
 			(if (not (eq new-duration t))
 			    (setq duration new-duration))
 			(setq result (add-fractions result
 						    (list (* numerator (car duration))
 							  (* denominator (cadr duration)))))
 			(goto-note-begin))
 		      (if (< (point) end)
 			  (forward-char 1)))) ; skip }
 
 		(if (not (eq new-duration t))
 		    (setq duration new-duration))
 		(setq result (add-fractions result duration)))
 	      (goto-note-begin)))
 
 	  result)))))
 
 (defun LilyPond-what-beat ()
   "Returns how much of a measure lies between last measaure '|' and point.
 Recognizes chords, and triples."
   (interactive)
   (let ((beat (get-beat)))
     (message "Beat: %d/%d" (car beat) (cadr beat)))
   )
 
 (defun LilyPond-electric-bar ()
   "Indicate the number of beats in last measure when a | is inserted"
   (interactive)
   (self-insert-command 1)
   (save-excursion
     (save-restriction
       (backward-char)
       (LilyPond-what-beat)
       (forward-char)
       )))