X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=scm%2Fmusic-functions.scm;h=c31360019912c04285896b5c1e3a19381d5f8736;hb=54b02666750062788185bd3f99e644d621e348c2;hp=95587b8670bf84ab44daf03b2ccfee66875f9936;hpb=ca5ffa906698b69799dffc2461de29762847a11c;p=lilypond.git

diff --git a/scm/music-functions.scm b/scm/music-functions.scm
index 95587b8670..c313600199 100644
--- a/scm/music-functions.scm
+++ b/scm/music-functions.scm
@@ -1,6 +1,6 @@
 ;;;; This file is part of LilyPond, the GNU music typesetter.
 ;;;;
-;;;; Copyright (C) 1998--2010 Jan Nieuwenhuizen <janneke@gnu.org>
+;;;; Copyright (C) 1998--2011 Jan Nieuwenhuizen <janneke@gnu.org>
 ;;;;                 Han-Wen Nienhuys <hanwen@xs4all.nl>
 ;;;;
 ;;;; LilyPond is free software: you can redistribute it and/or modify
@@ -55,8 +55,8 @@
 (define-public (music-map function music)
   "Apply @var{function} to @var{music} and all of the music it contains.
 
-First it recurses over the children, then the function is applied to MUSIC.
-"
+First it recurses over the children, then the function is applied to
+@var{music}."
   (let ((es (ly:music-property music 'elements))
 	(e (ly:music-property music 'element)))
     (set! (ly:music-property music 'elements)
@@ -67,7 +67,7 @@ First it recurses over the children, then the function is applied to MUSIC.
     (function music)))
 
 (define-public (music-filter pred? music)
-  "Filter out music expressions that do not satisfy PRED."
+  "Filter out music expressions that do not satisfy @var{pred?}."
 
   (define (inner-music-filter pred? music)
     "Recursive function."
@@ -96,7 +96,8 @@ First it recurses over the children, then the function is applied to MUSIC.
       (make-music 'Music)))	  ;must return music.
 
 (define-public (display-music music)
-  "Display music, not done with music-map for clarity of presentation."
+  "Display music, not done with @code{music-map} for clarity of
+presentation."
 
   (display music)
   (display ": { ")
@@ -147,8 +148,9 @@ For instance,
       `(markup ,@(inner-markup->make-markup markup-expression))))
 
 (define-public (music->make-music obj)
-  "Generate a expression that, once evaluated, may return an object equivalent to `obj',
-that is, for a music expression, a (make-music ...) form."
+  "Generate an expression that, once evaluated, may return an object
+equivalent to @var{obj}, that is, for a music expression, a
+@code{(make-music ...)} form."
   (cond (;; markup expression
 	 (markup? obj)
 	 (markup-expression->make-markup obj))
@@ -227,9 +229,9 @@ Returns `obj'.
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (define-public (shift-one-duration-log music shift dot)
-  "  add SHIFT to duration-log of 'duration in music and optionally
-  a dot to any note encountered. This scales the music up by a factor
-  2^shift * (2 - (1/2)^dot)"
+  "Add @var{shift} to @code{duration-log} of @code{'duration} in
+@var{music} and optionally @var{dot} to any note encountered.  This
+scales the music up by a factor `2^@var{shift} * (2 - (1/2)^@var{dot})'."
   (let ((d (ly:music-property music 'duration)))
     (if (ly:duration? d)
 	(let* ((cp (ly:duration-factor d))
@@ -245,7 +247,8 @@ Returns `obj'.
 	     music))
 
 (define-public (make-repeat name times main alts)
-  "create a repeat music expression, with all properties initialized properly"
+  "Create a repeat music expression, with all properties initialized
+properly."
   (define (first-note-duration music)
     "Finds the duration of the first NoteEvent by searching depth-first
 through MUSIC."
@@ -275,7 +278,7 @@ through MUSIC."
 	;; This works for single-note and multi-note tremolos!
 	(let* ((children (if (music-is-of-type? main 'sequential-music)
 			     ;; \repeat tremolo n { ... }
-			     (length (ly:music-property main 'elements))
+			     (length (extract-named-music main 'EventChord))
 			     ;; \repeat tremolo n c4
 			     1))
 	       ;; # of dots is equal to the 1 in bitwise representation (minus 1)!
@@ -298,11 +301,25 @@ through MUSIC."
 	  (shift-duration-log r shift dots))
 	r)))
 
+(define (calc-repeat-slash-count music)
+  "Given the child-list @var{music} in @code{PercentRepeatMusic},
+calculate the number of slashes based on the durations.  Returns @code{0}
+if durations in @var{music} vary, allowing slash beats and double-percent
+beats to be distinguished."
+  (let* ((durs (map (lambda (elt)
+		      (duration-of-note elt))
+		    (extract-named-music music 'EventChord)))
+	 (first-dur (car durs)))
+
+    (if (every (lambda (d) (equal? d first-dur)) durs)
+	(max (- (ly:duration-log first-dur) 2) 1)
+	0)))
+
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; clusters.
 
 (define-public (note-to-cluster music)
-  "Replace NoteEvents by ClusterNoteEvents."
+  "Replace @code{NoteEvents} by @code{ClusterNoteEvents}."
   (if (eq? (ly:music-property music 'name) 'NoteEvent)
       (make-music 'ClusterNoteEvent
 		  'pitch (ly:music-property music 'pitch)
@@ -316,7 +333,7 @@ through MUSIC."
 ;; repeats.
 
 (define-public (unfold-repeats music)
-  "This function replaces all repeats with unfolded repeats."
+  "Replace all repeats with unfolded repeats."
 
   (let ((es (ly:music-property music 'elements))
 	(e (ly:music-property music 'element)))
@@ -360,8 +377,8 @@ through MUSIC."
 ;; property setting music objs.
 
 (define-public (make-grob-property-set grob gprop val)
-  "Make a Music expression that sets GPROP to VAL in GROB. Does a pop first,
-i.e.  this is not an override"
+  "Make a @code{Music} expression that sets @var{gprop} to @var{val} in
+@var{grob}.  Does a pop first, i.e., this is not an override."
   (make-music 'OverrideProperty
 	      'symbol grob
 	      'grob-property gprop
@@ -369,14 +386,15 @@ i.e.  this is not an override"
 	      'pop-first #t))
 
 (define-public (make-grob-property-override grob gprop val)
-  "Make a Music expression that overrides GPROP to VAL in GROB."
+  "Make a @code{Music} expression that overrides @var{gprop} to @var{val}
+in @var{grob}."
   (make-music 'OverrideProperty
 	      'symbol grob
 	      'grob-property gprop
 	      'grob-value val))
 
 (define-public (make-grob-property-revert grob gprop)
-  "Revert the grob property GPROP for GROB."
+  "Revert the grob property @var{gprop} for @var{grob}."
   (make-music 'RevertProperty
 	      'symbol grob
 	      'grob-property gprop))
@@ -393,7 +411,8 @@ i.e.  this is not an override"
     Slur
     Stem
     TextScript
-    Tie))
+    Tie
+    TupletBracket))
 
 (define-safe-public (make-voice-props-set n)
   (make-sequential-music
@@ -432,7 +451,7 @@ i.e.  this is not an override"
 
 
 (define-safe-public (context-spec-music m context #:optional id)
-  "Add \\context CONTEXT = ID to M. "
+  "Add \\context CONTEXT = ID to M."
   (let ((cm (make-music 'ContextSpeccedMusic
 			'element m
 			'context-type context)))
@@ -441,7 +460,7 @@ i.e.  this is not an override"
     cm))
 
 (define-public (descend-to-context m context)
-  "Like context-spec-music, but only descending. "
+  "Like @code{context-spec-music}, but only descending."
   (let ((cm (context-spec-music m context)))
     (ly:music-set-property! cm 'descend-only #t)
     cm))
@@ -493,7 +512,7 @@ i.e.  this is not an override"
 
 ;;; Need to keep this definition for \time calls from parser
 (define-public (make-time-signature-set num den)
-  "Set properties for time signature NUM/DEN."
+  "Set properties for time signature @var{num}/@var{den}."
   (make-music 'TimeSignatureMusic
               'numerator num
               'denominator den
@@ -501,9 +520,8 @@ i.e.  this is not an override"
 
 ;;; Used for calls that include beat-grouping setting
 (define-public (set-time-signature num den . rest)
-  "Set properties for time signature @var{num/den}.
-If @var{rest} is present, it is used to set
-@code{beatStructure}."
+  "Set properties for time signature @var{num}/@var{den}.
+If @var{rest} is present, it is used to set @code{beatStructure}."
   (ly:export
    (make-music 'TimeSignatureMusic
 	       'numerator num
@@ -559,14 +577,14 @@ inside of and outside of chord construct."
           (revert-head-style heads)))))
 
  (define-public (set-mus-properties! m alist)
-  "Set all of ALIST as properties of M."
+  "Set all of @var{alist} as properties of @var{m}."
   (if (pair? alist)
       (begin
 	(set! (ly:music-property m (caar alist)) (cdar alist))
 	(set-mus-properties! m (cdr alist)))))
 
 (define-public (music-separator? m)
-  "Is M a separator?"
+  "Is @var{m} a separator?"
   (let ((ts (ly:music-property m 'types)))
     (memq 'separator ts)))
 
@@ -574,10 +592,10 @@ inside of and outside of chord construct."
 (define (voicify-list lst number)
   "Make a list of Musics.
 
-   voicify-list :: [ [Music ] ] -> number -> [Music]
-   LST is a list music-lists.
+voicify-list :: [ [Music ] ] -> number -> [Music]
+LST is a list music-lists.
 
-   NUMBER is 0-base, i.e. Voice=1 (upstems) has number 0.
+NUMBER is 0-base, i.e., Voice=1 (upstems) has number 0.
 "
   (if (null? lst)
       '()
@@ -596,7 +614,7 @@ inside of and outside of chord construct."
     ch))
 
 (define-public (voicify-music m)
-  "Recursively split chords that are separated with \\ "
+  "Recursively split chords that are separated with @code{\\\\}."
   (if (not (ly:music? m))
       (ly:error (_ "music expected: ~S") m))
   (let ((es (ly:music-property m 'elements))
@@ -625,11 +643,8 @@ inside of and outside of chord construct."
 
 
 (define-public ((set-output-property grob-name symbol val)  grob grob-c context)
-  "Usage:
-
-\\applyoutput #(set-output-property 'Clef 'extra-offset '(0 . 1))
-
-"
+  "Usage example:
+@code{\\applyoutput #(set-output-property 'Clef 'extra-offset '(0 . 1))}"
   (let ((meta (ly:grob-property grob 'meta)))
     (if (equal? (assoc-get 'name meta) grob-name)
 	(set! (ly:grob-property grob symbol) val))))
@@ -637,13 +652,11 @@ inside of and outside of chord construct."
 
 ;;
 (define-public (smart-bar-check n)
-  "Make	 a bar check that checks for a specific bar number.
-"
+  "Make a bar check that checks for a specific bar number."
   (let ((m (make-music 'ApplyContext)))
     (define (checker tr)
       (let* ((bn (ly:context-property tr 'currentBarNumber)))
-	(if (= bn n)
-	    #t
+	(or (= bn n)
 	    (ly:error
 	     ;; FIXME: uncomprehensable message
 	     (_ "Bar check failed.  Expect to be at ~a, instead at ~a")
@@ -653,9 +666,8 @@ inside of and outside of chord construct."
 
 
 (define-public (skip->rest mus)
-
-  "Replace MUS by RestEvent of the same duration if it is a
-SkipEvent. Useful for extracting parts from crowded scores"
+  "Replace @var{mus} by @code{RestEvent} of the same duration if it is a
+@code{SkipEvent}.  Useful for extracting parts from crowded scores."
 
   (if  (memq (ly:music-property mus 'name) '(SkipEvent SkipMusic))
    (make-music 'RestEvent 'duration (ly:music-property mus 'duration))
@@ -701,20 +713,20 @@ SkipEvent. Useful for extracting parts from crowded scores"
     nv))
 
 (define (vector-map f v)
-  "Map	F over V. This function returns nothing."
+  "Map F over V.  This function returns nothing."
   (do ((n (vector-length v))
        (i 0 (+ i 1)))
       ((>= i n))
     (f (vector-ref v i))))
 
 (define (vector-reverse-map f v)
-  "Map	F over V, N to 0 order. This function returns nothing."
+  "Map F over V, N to 0 order.  This function returns nothing."
   (do ((i (- (vector-length v) 1) (- i 1)))
       ((< i 0))
     (f (vector-ref v i))))
 
 (define-public (add-grace-property context-name grob sym val)
-  "Set SYM=VAL for GROB in CONTEXT-NAME. "
+  "Set @var{sym}=@var{val} for @var{grob} in @var{context-name}."
   (define (set-prop context)
     (let* ((where (ly:context-property-where-defined context 'graceSettings))
 	   (current (ly:context-property where 'graceSettings))
@@ -724,7 +736,7 @@ SkipEvent. Useful for extracting parts from crowded scores"
   (ly:export (context-spec-music (make-apply-context set-prop) 'Voice)))
 
 (define-public (remove-grace-property context-name grob sym)
-  "Remove all SYM for GROB in CONTEXT-NAME. "
+  "Remove all @var{sym} for @var{grob} in @var{context-name}."
   (define (sym-grob-context? property sym grob context-name)
     (and (eq? (car property) context-name)
          (eq? (cadr property) grob)
@@ -778,10 +790,11 @@ Syntax:
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (define-public (cue-substitute quote-music)
-  "Must happen after quote-substitute."
+  "Must happen after @code{quote-substitute}."
 
   (if (vector? (ly:music-property quote-music 'quoted-events))
       (let* ((dir (ly:music-property quote-music 'quoted-voice-direction))
+	     (clef (ly:music-property quote-music 'quoted-music-clef))
 	     (main-voice (if (eq? 1 dir) 1 0))
 	     (cue-voice (if (eq? 1 dir) 0 1))
 	     (main-music (ly:music-property quote-music 'element))
@@ -793,14 +806,19 @@ Syntax:
 	    ;; to have opposite stems.
 	    (begin
 	      (set! return-value
-
 		    ;; cannot context-spec Quote-music, since context
 		    ;; for the quotes is determined in the iterator.
 		    (make-sequential-music
 		     (list
+		      (if (null? clef)
+		          (make-music 'Music)
+		          (make-cue-clef-set clef))
 		      (context-spec-music (make-voice-props-set cue-voice) 'CueVoice "cue")
 		      quote-music
-		      (context-spec-music (make-voice-props-revert)  'CueVoice "cue"))))
+		      (context-spec-music (make-voice-props-revert) 'CueVoice "cue")
+		      (if (null? clef)
+		          (make-music 'Music)
+		          (make-cue-clef-unset)))))
 	      (set! main-music
 		    (make-sequential-music
 		     (list
@@ -814,9 +832,8 @@ Syntax:
 
 (define-public ((quote-substitute quote-tab) music)
   (let* ((quoted-name (ly:music-property music 'quoted-music-name))
-	 (quoted-vector (if (string? quoted-name)
-			    (hash-ref quote-tab quoted-name #f)
-			    #f)))
+	 (quoted-vector (and (string? quoted-name)
+			     (hash-ref quote-tab quoted-name #f))))
 
 
     (if (string? quoted-name)
@@ -859,37 +876,26 @@ Syntax:
   music)
 
 (define-public (make-duration-of-length moment)
- "Make duration of the given MOMENT length."
+ "Make duration of the given @code{moment} length."
  (ly:make-duration 0 0
   (ly:moment-main-numerator moment)
   (ly:moment-main-denominator moment)))
 
-(define (skip-this moment)
- "set skipTypesetting, make SkipMusic of the given MOMENT length,
- and then unset skipTypesetting."
- (make-sequential-music
-  (list
-   (context-spec-music (make-property-set 'skipTypesetting #t)
-    'Score)
-   (make-music 'SkipMusic 'duration
-    (make-duration-of-length moment))
-   (context-spec-music (make-property-set 'skipTypesetting #f)
-    'Score))))
-
-(define (unskip-this moment)
- "unset skipTypesetting, make SkipMusic of the given MOMENT length,
- and then set skipTypesetting."
+(define (make-skipped moment bool)
+ "Depending on BOOL, set or unset skipTypesetting,
+then make SkipMusic of the given MOMENT length, and
+then revert skipTypesetting."
  (make-sequential-music
   (list
-   (context-spec-music (make-property-set 'skipTypesetting #f)
+   (context-spec-music (make-property-set 'skipTypesetting bool)
     'Score)
    (make-music 'SkipMusic 'duration
     (make-duration-of-length moment))
-   (context-spec-music (make-property-set 'skipTypesetting #t)
+   (context-spec-music (make-property-set 'skipTypesetting (not bool))
     'Score))))
 
 (define (skip-as-needed music parser)
- "Replace MUSIC by
+  "Replace MUSIC by
  << {  \\set skipTypesetting = ##f
  LENGTHOF(\\showFirstLength)
  \\set skipTypesetting = ##t
@@ -900,51 +906,54 @@ Syntax:
  When only showFirstLength is set,
  the 'length property of the music is
  overridden to speed up compiling."
- (let*
-  ((show-last (ly:parser-lookup parser 'showLastLength))
-   (show-first (ly:parser-lookup parser 'showFirstLength)))
-  (cond
-
-   ;; both properties may be set.
-   ((and (ly:music? show-first) (ly:music? show-last))
-    (let*
-     ((orig-length (ly:music-length music))
-      (skip-length (ly:moment-sub orig-length (ly:music-length show-last)))
-      (begin-length (ly:music-length show-first)))
-     (make-simultaneous-music
-      (list
-       (make-sequential-music
-        (list
-         (skip-this skip-length)
-         ;; let's draw a separator between the beginning and the end
-         (context-spec-music (make-property-set 'whichBar "||")
-          'Timing)))
-       (unskip-this begin-length)
-       music))))
-
-   ;; we may only want to print the last length
-   ((ly:music? show-last)
-    (let*
-     ((orig-length (ly:music-length music))
-      (skip-length (ly:moment-sub orig-length (ly:music-length show-last))))
-     (make-simultaneous-music
-      (list
-       (skip-this skip-length)
-       music))))
-
-   ;; we may only want to print the beginning; in this case
-   ;; only the first length will be processed (much faster).
-   ((ly:music? show-first)
-    (let*
-     ((orig-length (ly:music-length music))
-      (begin-length (ly:music-length show-first)))
-     ;; the first length must not exceed the original length.
-     (if (ly:moment<? begin-length orig-length)
-      (set! (ly:music-property music 'length)
-       (ly:music-length show-first)))
-     music))
-
-   (else music))))
+  (let*
+      ((show-last (ly:parser-lookup parser 'showLastLength))
+       (show-first (ly:parser-lookup parser 'showFirstLength))
+       (show-last-length (and (ly:music? show-last)
+			      (ly:music-length show-last)))
+       (show-first-length (and (ly:music? show-first)
+			       (ly:music-length show-first)))
+       (orig-length (ly:music-length music)))
+
+    ;;FIXME: if using either showFirst- or showLastLength,
+    ;; make sure that skipBars is not set.
+
+    (cond
+
+     ;; both properties may be set.
+     ((and show-first-length show-last-length)
+      (let
+          ((skip-length (ly:moment-sub orig-length show-last-length)))
+        (make-simultaneous-music
+         (list
+          (make-sequential-music
+           (list
+            (make-skipped skip-length #t)
+            ;; let's draw a separator between the beginning and the end
+            (context-spec-music (make-property-set 'whichBar "||")
+                                'Timing)))
+          (make-skipped show-first-length #f)
+          music))))
+
+     ;; we may only want to print the last length
+     (show-last-length
+      (let
+          ((skip-length (ly:moment-sub orig-length show-last-length)))
+        (make-simultaneous-music
+         (list
+          (make-skipped skip-length #t)
+          music))))
+
+     ;; we may only want to print the beginning; in this case
+     ;; only the first length will be processed (much faster).
+     (show-first-length
+      ;; the first length must not exceed the original length.
+      (if (ly:moment<? show-first-length orig-length)
+          (set! (ly:music-property music 'length)
+                show-first-length))
+      music)
+
+     (else music))))
 
 
 (define-public toplevel-music-functions
@@ -992,17 +1001,22 @@ Syntax:
 ;; accidentals
 
 (define (recent-enough? bar-number alteration-def laziness)
-  (if (or (number? alteration-def)
-	  (equal? laziness #t))
-      #t
+  (or (number? alteration-def)
+      (equal? laziness #t)
       (<= bar-number (+ (cadr alteration-def) laziness))))
 
-(define (is-tied? alteration-def)
-  (let* ((def (if (pair? alteration-def)
-		 (car alteration-def)
-		 alteration-def)))
+(define (accidental-invalid? alteration-def)
+  "Checks an alteration entry for being invalid.
+
+Non-key alterations are invalidated when tying into the next bar or
+when there is a clef change, since neither repetition nor cancellation
+can be omitted when the same note occurs again.
 
-    (if (equal? def 'tied) #t #f)))
+Returns @code{#f} or the reason for the invalidation, a symbol."
+  (let* ((def (if (pair? alteration-def)
+		  (car alteration-def)
+		  alteration-def)))
+    (and (symbol? def) def)))
 
 (define (extract-alteration alteration-def)
   (cond ((number? alteration-def)
@@ -1013,7 +1027,7 @@ Syntax:
 
 (define (check-pitch-against-signature context pitch barnum laziness octaveness)
   "Checks the need for an accidental and a @q{restore} accidental against
-@code{localKeySignature}. The @var{laziness} is the number of measures
+@code{localKeySignature}.  The @var{laziness} is the number of measures
 for which reminder accidentals are used (i.e., if @var{laziness} is zero,
 only cancel accidentals in the same measure; if @var{laziness} is three,
 we cancel accidentals up to three measures after they first appear.
@@ -1035,14 +1049,13 @@ specifies whether accidentals should be canceled in different octaves."
 	 (previous-alteration #f)
 	 (from-other-octaves #f)
 	 (from-same-octave (assoc-get pitch-handle local-key-sig))
-	 (from-key-sig (assoc-get notename local-key-sig)))
+	 (from-key-sig (or (assoc-get notename local-key-sig)
 
     ;; If no key signature match is found from localKeySignature, we may have a custom
     ;; type with octave-specific entries of the form ((octave . pitch) alteration)
     ;; instead of (pitch . alteration).  Since this type cannot coexist with entries in
     ;; localKeySignature, try extracting from keySignature instead.
-    (if (equal? from-key-sig #f)
-	(set! from-key-sig (assoc-get pitch-handle key-sig)))
+			   (assoc-get pitch-handle key-sig))))
 
     ;; loop through localKeySignature to search for a notename match from other octaves
     (let loop ((l local-key-sig))
@@ -1056,22 +1069,22 @@ specifies whether accidentals should be canceled in different octaves."
     ;; find previous alteration-def for comparison with pitch
     (cond
      ;; from same octave?
-     ((and (eq? ignore-octave #f)
-	   (not (equal? from-same-octave #f))
+     ((and (not ignore-octave)
+	   from-same-octave
 	   (recent-enough? barnum from-same-octave laziness))
       (set! previous-alteration from-same-octave))
 
      ;; from any octave?
-     ((and (eq? ignore-octave #t)
-	   (not (equal? from-other-octaves #f))
+     ((and ignore-octave
+	   from-other-octaves
 	   (recent-enough? barnum from-other-octaves laziness))
       (set! previous-alteration from-other-octaves))
 
      ;; not recent enough, extract from key signature/local key signature
-     ((not (equal? from-key-sig #f))
+     (from-key-sig
       (set! previous-alteration from-key-sig)))
 
-    (if (is-tied? previous-alteration)
+    (if (accidental-invalid? previous-alteration)
 	(set! need-accidental #t)
 
 	(let* ((prev-alt (extract-alteration previous-alteration))
@@ -1081,29 +1094,33 @@ specifies whether accidentals should be canceled in different octaves."
 	      (begin
 		(set! need-accidental #t)
 		(if (and (not (= this-alt 0))
-			 (or (< (abs this-alt) (abs prev-alt))
-			     (< (* prev-alt this-alt) 0)))
+			 (and (< (abs this-alt) (abs prev-alt))
+			     (> (* prev-alt this-alt) 0)))
 		    (set! need-restore #t))))))
 
     (cons need-restore need-accidental)))
 
 (define-public ((make-accidental-rule octaveness laziness) context pitch barnum measurepos)
-  "Creates an accidental rule that makes its decision based on the octave of the note
-  and a laziness value.
-  octaveness is either 'same-octave or 'any-octave and defines whether the rule should
-  respond to accidental changes in other octaves than the current. 'same-octave is the
-  normal way to typeset accidentals - an accidental is made if the alteration is different
-  from the last active pitch in the same octave. 'any-octave looks at the last active pitch
-  in any octave.
-  laziness states over how many bars an accidental should be remembered.
-  0 is default - accidental lasts over 0 bar lines, that is, to the end of current measure.
-  A positive integer means that the accidental lasts over that many bar lines.
-  -1 is 'forget immediately', that is, only look at key signature.
-  #t is forever."
+  "Create an accidental rule that makes its decision based on the octave of
+the note and a laziness value.
+
+@var{octaveness} is either @code{'same-octave} or @code{'any-octave} and
+defines whether the rule should respond to accidental changes in other
+octaves than the current.  @code{'same-octave} is the normal way to typeset
+accidentals -- an accidental is made if the alteration is different from the
+last active pitch in the same octave.  @code{'any-octave} looks at the last
+active pitch in any octave.
+
+@var{laziness} states over how many bars an accidental should be remembered.
+@code{0}@tie{}is the default -- accidental lasts over 0@tie{}bar lines, that
+is, to the end of current measure.  A positive integer means that the
+accidental lasts over that many bar lines.  @code{-1} is `forget
+immediately', that is, only look at key signature.  @code{#t} is `forever'."
+
   (check-pitch-against-signature context pitch barnum laziness octaveness))
 
 (define (key-entry-notename entry)
-  "Return the pitch of an entry in localKeySignature. The entry is either of the form
+  "Return the pitch of an entry in localKeySignature.  The entry is either of the form
   '(notename . alter) or '((octave . notename) . (alter barnum . measurepos))."
   (if (number? (car entry))
       (car entry)
@@ -1125,42 +1142,43 @@ specifies whether accidentals should be canceled in different octaves."
   (and (pair? (car entry)) (cdddr entry)))
 
 (define (key-entry-alteration entry)
-  "Return the alteration of an entry in localKeySignature."
-  (if (number? (car entry))
-      (cdr entry)
-      (cadr entry)))
+  "Return the alteration of an entry in localKeySignature.
+
+For convenience, returns @code{0} if entry is @code{#f}."
+  (if entry
+      (if (number? (car entry))
+	  (cdr entry)
+	  (cadr entry))
+      0))
 
 (define-public (find-pitch-entry keysig pitch accept-global accept-local)
-  "Return the first entry in keysig that matches the pitch.
-  accept-global states whether key signature entries should be included.
-  accept-local states whether local accidentals should be included.
-  if no matching entry is found, #f is returned."
-  (if (pair? keysig)
-      (let* ((entry (car keysig))
-	     (entryoct (key-entry-octave entry))
-	     (entrynn (key-entry-notename entry))
-	     (oct (ly:pitch-octave pitch))
-	     (nn (ly:pitch-notename pitch)))
-	(if (and (equal? nn entrynn)
-		 (or (and accept-global (equal? #f entryoct))
-		     (and accept-local (equal? oct entryoct))))
-	    entry
-	    (find-pitch-entry (cdr keysig) pitch accept-global accept-local)))
-      #f))
+  "Return the first entry in @var{keysig} that matches @var{pitch}.
+@var{accept-global} states whether key signature entries should be included.
+@var{accept-local} states whether local accidentals should be included.
+If no matching entry is found, @var{#f} is returned."
+  (and (pair? keysig)
+       (let* ((entry (car keysig))
+	      (entryoct (key-entry-octave entry))
+	      (entrynn (key-entry-notename entry))
+	      (oct (ly:pitch-octave pitch))
+	      (nn (ly:pitch-notename pitch)))
+	 (if (and (equal? nn entrynn)
+		  (or (and accept-global (not entryoct))
+		      (and accept-local (equal? oct entryoct))))
+	     entry
+	     (find-pitch-entry (cdr keysig) pitch accept-global accept-local)))))
 
 (define-public (neo-modern-accidental-rule context pitch barnum measurepos)
-  "an accidental rule that typesets an accidental if it differs from the key signature
-   AND does not directly follow a note on the same staff-line.
-   This rule should not be used alone because it does neither look at bar lines
-   nor different accidentals at the same notename"
+  "An accidental rule that typesets an accidental if it differs from the
+key signature @emph{and} does not directly follow a note on the same
+staff line.  This rule should not be used alone because it does neither
+look at bar lines nor different accidentals at the same note name."
   (let* ((keysig (ly:context-property context 'localKeySignature))
 	 (entry (find-pitch-entry keysig pitch #t #t)))
-    (if (equal? #f entry)
+    (if (not entry)
 	(cons #f #f)
 	(let* ((global-entry (find-pitch-entry keysig pitch #t #f))
-	       (key-acc (if (equal? global-entry #f)
-			    0
-			    (key-entry-alteration global-entry)))
+	       (key-acc (key-entry-alteration global-entry))
 	       (acc (ly:pitch-alteration pitch))
 	       (entrymp (key-entry-measure-position entry))
 	       (entrybn (key-entry-bar-number entry)))
@@ -1168,17 +1186,15 @@ specifies whether accidentals should be canceled in different octaves."
 			    (and (equal? entrybn barnum) (equal? entrymp measurepos)))))))))
 
 (define-public (teaching-accidental-rule context pitch barnum measurepos)
-  "an accidental rule that typesets a cautionary accidental
-  if it is included in the key signature AND does not directly follow
-  a note on the same staff-line."
+  "An accidental rule that typesets a cautionary accidental if it is
+included in the key signature @emph{and} does not directly follow a note
+on the same staff line."
   (let* ((keysig (ly:context-property context 'localKeySignature))
 	 (entry (find-pitch-entry keysig pitch #t #t)))
-    (if (equal? #f entry)
+    (if (not entry)
 	(cons #f #f)
 	(let* ((global-entry (find-pitch-entry keysig pitch #f #f))
-	       (key-acc (if (equal? global-entry #f)
-			    0
-			    (key-entry-alteration global-entry)))
+	       (key-acc (key-entry-alteration global-entry))
 	       (acc (ly:pitch-alteration pitch))
 	       (entrymp (key-entry-measure-position entry))
 	       (entrybn (key-entry-bar-number entry)))
@@ -1198,9 +1214,10 @@ specifies whether accidentals should be canceled in different octaves."
    context))
 
 (define-public (set-accidental-style style . rest)
-  "Set accidental style to STYLE. Optionally takes a context argument,
-e.g. 'Staff or 'Voice. The context defaults to Staff, except for piano styles, which
-use GrandStaff as a context. "
+  "Set accidental style to @var{style}.  Optionally take a context
+argument, e.g. @code{'Staff} or @code{'Voice}.  The context defaults
+to @code{Staff}, except for piano styles, which use @code{GrandStaff}
+as a context."
   (let ((context (if (pair? rest)
 		     (car rest) 'Staff))
 	(pcontext (if (pair? rest)
@@ -1361,10 +1378,40 @@ use GrandStaff as a context. "
        (ly:warning (_ "unknown accidental style: ~S") style)
        (make-sequential-music '()))))))
 
+(define-public (invalidate-alterations context)
+  "Invalidate alterations in @var{context}.
+
+Elements of @code{'localKeySignature} corresponding to local
+alterations of the key signature have the form
+@code{'((octave . notename) . (alter barnum . measurepos))}.
+Replace them with a version where @code{alter} is set to @code{'clef}
+to force a repetition of accidentals.
+
+Entries that conform with the current key signature are not invalidated."
+  (let* ((keysig (ly:context-property context 'keySignature)))
+    (set! (ly:context-property context 'localKeySignature)
+	  (map-in-order
+	   (lambda (entry)
+	     (let* ((localalt (key-entry-alteration entry))
+		    (localoct (key-entry-octave entry)))
+	       (if (or (accidental-invalid? localalt)
+		       (not localoct)
+		       (= localalt
+			  (key-entry-alteration
+			   (find-pitch-entry
+			    keysig
+			    (ly:make-pitch localoct
+					   (key-entry-notename entry)
+					   0)
+			    #t #t))))
+		   entry
+		   (cons (car entry) (cons 'clef (cddr entry))))))
+	   (ly:context-property context 'localKeySignature)))))
+  		    
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (define-public (skip-of-length mus)
-  "Create a skip of exactly the same length as MUS."
+  "Create a skip of exactly the same length as @var{mus}."
   (let* ((skip
 	  (make-music
 	   'SkipEvent
@@ -1373,7 +1420,7 @@ use GrandStaff as a context. "
     (make-event-chord (list (ly:music-compress skip (ly:music-length mus))))))
 
 (define-public (mmrest-of-length mus)
-  "Create a mmrest of exactly the same length as MUS."
+  "Create a multi-measure rest of exactly the same length as @var{mus}."
 
   (let* ((skip
 	  (make-multi-measure-rest
@@ -1382,20 +1429,25 @@ use GrandStaff as a context. "
     skip))
 
 (define-public (pitch-of-note event-chord)
+  (let ((evs (filter (lambda (x)
+		       (music-has-type x 'note-event))
+		     (ly:music-property event-chord 'elements))))
 
-  (let*
-      ((evs (filter (lambda (x) (memq 'note-event (ly:music-property x 'types)))
-		    (ly:music-property event-chord 'elements))))
+    (and (pair? evs)
+	 (ly:music-property (car evs) 'pitch))))
+
+(define-public (duration-of-note event-chord)
+  (let ((evs (filter (lambda (x)
+		       (music-has-type x 'rhythmic-event))
+		     (ly:music-property event-chord 'elements))))
 
-    (if (pair? evs)
-	(ly:music-property (car evs) 'pitch)
-	#f)))
+    (and (pair? evs)
+	 (ly:music-property (car evs) 'duration))))
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (define-public (extract-named-music music music-name)
-"Return a flat list of all music named @code{music-name}
-from @code{music}."
+  "Return a flat list of all music named @var{music-name} from @var{music}."
    (let ((extracted-list
           (if (ly:music? music)
               (if (eq? (ly:music-property music 'name) music-name)
@@ -1413,12 +1465,12 @@ from @code{music}."
      (flatten-list extracted-list)))
 
 (define-public (event-chord-notes event-chord)
-"Return a list of all notes from @{event-chord}."
+  "Return a list of all notes from @var{event-chord}."
   (filter
     (lambda (m) (eq? 'NoteEvent (ly:music-property m 'name)))
     (ly:music-property event-chord 'elements)))
 
 (define-public (event-chord-pitches event-chord)
-"Return a list of all pitches from @{event-chord}."
+  "Return a list of all pitches from @var{event-chord}."
   (map (lambda (x) (ly:music-property x 'pitch))
        (event-chord-notes event-chord)))