+(define (recent-enough? bar-number alteration-def laziness)
+ (if (or (number? alteration-def)
+ (equal? laziness #t))
+ #t
+ (<= bar-number (+ (cadr alteration-def) laziness))))
+
+(define (is-tied? alteration-def)
+ (let* ((def (if (pair? alteration-def)
+ (car alteration-def)
+ alteration-def)))
+
+ (if (equal? def 'tied) #t #f)))
+
+(define (extract-alteration alteration-def)
+ (cond ((number? alteration-def)
+ alteration-def)
+ ((pair? alteration-def)
+ (car alteration-def))
+ (else 0)))
+
+(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
+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.
+@var{octaveness} is either @code{'same-octave} or @code{'any-octave} and
+specifies whether accidentals should be canceled in different octaves."
+ (let* ((ignore-octave (cond ((equal? octaveness 'any-octave) #t)
+ ((equal? octaveness 'same-octave) #f)
+ (else
+ (ly:warning (_ "Unknown octaveness type: ~S ") octaveness)
+ (ly:warning (_ "Defaulting to 'any-octave."))
+ #t)))
+ (key-sig (ly:context-property context 'keySignature))
+ (local-key-sig (ly:context-property context 'localKeySignature))
+ (notename (ly:pitch-notename pitch))
+ (octave (ly:pitch-octave pitch))
+ (pitch-handle (cons octave notename))
+ (need-restore #f)
+ (need-accidental #f)
+ (previous-alteration #f)
+ (from-other-octaves #f)
+ (from-same-octave (ly:assoc-get pitch-handle local-key-sig))
+ (from-key-sig (ly: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 (ly:assoc-get pitch-handle key-sig)))
+
+ ;; loop through localKeySignature to search for a notename match from other octaves
+ (let loop ((l local-key-sig))
+ (if (pair? l)
+ (let ((entry (car l)))
+ (if (and (pair? (car entry))
+ (= (cdar entry) notename))
+ (set! from-other-octaves (cdr entry))
+ (loop (cdr l))))))
+
+ ;; find previous alteration-def for comparison with pitch
+ (cond
+ ;; from same octave?
+ ((and (eq? ignore-octave #f)
+ (not (equal? from-same-octave #f))
+ (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))
+ (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))
+ (set! previous-alteration from-key-sig)))
+
+ (if (is-tied? previous-alteration)
+ (set! need-accidental #t)
+
+ (let* ((prev-alt (extract-alteration previous-alteration))
+ (this-alt (ly:pitch-alteration pitch)))
+
+ (if (not (= this-alt prev-alt))
+ (begin
+ (set! need-accidental #t)
+ (if (and (not (= this-alt 0))
+ (or (< (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."
+ (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
+ '(notename . alter) or '((octave . notename) . (alter barnum . measurepos))."
+ (if (number? (car entry))
+ (car entry)
+ (cdar entry)))
+
+(define (key-entry-octave entry)
+ "Return the octave of an entry in localKeySignature (or #f if the entry does not have
+ an octave)."
+ (and (pair? (car entry)) (caar entry)))
+
+(define (key-entry-bar-number entry)
+ "Return the bar number of an entry in localKeySignature (or #f if the entry does not
+ have a bar number)."
+ (and (pair? (car entry)) (caddr entry)))
+
+(define (key-entry-measure-position entry)
+ "Return the measure position of an entry in localKeySignature (or #f if the entry does
+ not have a measure position)."
+ (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)))
+
+(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))
+
+(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"
+ (let* ((keysig (ly:context-property context 'localKeySignature))
+ (entry (find-pitch-entry keysig pitch #t #t)))
+ (if (equal? #f 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)))
+ (acc (ly:pitch-alteration pitch))
+ (entrymp (key-entry-measure-position entry))
+ (entrybn (key-entry-bar-number entry)))
+ (cons #f (not (or (equal? acc key-acc)
+ (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."
+ (let* ((keysig (ly:context-property context 'localKeySignature))
+ (entry (find-pitch-entry keysig pitch #t #t)))
+ (if (equal? #f 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)))
+ (acc (ly:pitch-alteration pitch))
+ (entrymp (key-entry-measure-position entry))
+ (entrybn (key-entry-bar-number entry)))
+ (cons #f (not (or (equal? acc key-acc)
+ (and (equal? entrybn barnum) (equal? entrymp measurepos)))))))))
+