+;; accidentals
+
+(define-public ((make-accidental-rule octaveness lazyness) 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.
+ lazyness 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."
+ (let ((keysig (ly:context-property context 'localKeySignature)))
+ (ly:find-accidentals-simple keysig pitch barnum lazyness 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 (set-accidentals-properties extra-natural
+ auto-accs auto-cauts
+ context)
+ (context-spec-music
+ (make-sequential-music
+ (append (if (boolean? extra-natural)
+ (list (make-property-set 'extraNatural extra-natural))
+ '())
+ (list (make-property-set 'autoAccidentals auto-accs)
+ (make-property-set 'autoCautionaries auto-cauts))))
+ 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. "
+ (let ((context (if (pair? rest)
+ (car rest) 'Staff))
+ (pcontext (if (pair? rest)
+ (car rest) 'GrandStaff)))
+ (ly:export
+ (cond
+ ;; accidentals as they were common in the 18th century.
+ ((equal? style 'default)
+ (set-accidentals-properties #t
+ `(Staff ,(make-accidental-rule 'same-octave 0))
+ '()
+ context))
+ ;; accidentals from one voice do NOT get cancelled in other voices
+ ((equal? style 'voice)
+ (set-accidentals-properties #t
+ `(Voice ,(make-accidental-rule 'same-octave 0))
+ '()
+ context))
+ ;; accidentals as suggested by Kurt Stone, Music Notation in the 20th century.
+ ;; This includes all the default accidentals, but accidentals also needs cancelling
+ ;; in other octaves and in the next measure.
+ ((equal? style 'modern)
+ (set-accidentals-properties #f
+ `(Staff ,(make-accidental-rule 'same-octave 0)
+ ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1))
+ '()
+ context))
+ ;; the accidentals that Stone adds to the old standard as cautionaries
+ ((equal? style 'modern-cautionary)
+ (set-accidentals-properties #f
+ `(Staff ,(make-accidental-rule 'same-octave 0))
+ `(Staff ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1))
+ context))
+ ;; same as modern, but accidentals different from the key signature are always
+ ;; typeset - unless they directly follow a note of the same pitch.
+ ((equal? style 'neo-modern)
+ (set-accidentals-properties #f
+ `(Staff ,(make-accidental-rule 'same-octave 0)
+ ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1)
+ ,neo-modern-accidental-rule)
+ '()
+ context))
+ ((equal? style 'neo-modern-cautionary)
+ (set-accidentals-properties #f
+ `(Staff ,(make-accidental-rule 'same-octave 0))
+ `(Staff ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1)
+ ,neo-modern-accidental-rule)
+ context))
+ ;; Accidentals as they were common in dodecaphonic music with no tonality.
+ ;; Each note gets one accidental.
+ ((equal? style 'dodecaphonic)
+ (set-accidentals-properties #f
+ `(Staff ,(lambda (c p bn mp) '(#f . #t)))
+ '()
+ context))
+ ;; Multivoice accidentals to be read both by musicians playing one voice
+ ;; and musicians playing all voices.
+ ;; Accidentals are typeset for each voice, but they ARE cancelled across voices.
+ ((equal? style 'modern-voice)
+ (set-accidentals-properties #f
+ `(Voice ,(make-accidental-rule 'same-octave 0)
+ ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1)
+ Staff ,(make-accidental-rule 'same-octave 0)
+ ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1))
+ '()
+ context))
+ ;; same as modernVoiceAccidental eccept that all special accidentals are typeset
+ ;; as cautionaries
+ ((equal? style 'modern-voice-cautionary)
+ (set-accidentals-properties #f
+ `(Voice ,(make-accidental-rule 'same-octave 0))
+ `(Voice ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1)
+ Staff ,(make-accidental-rule 'same-octave 0)
+ ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1))
+ context))
+ ;; stone's suggestions for accidentals on grand staff.
+ ;; Accidentals are cancelled across the staves in the same grand staff as well
+ ((equal? style 'piano)
+ (set-accidentals-properties #f
+ `(Staff ,(make-accidental-rule 'same-octave 0)
+ ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1)
+ GrandStaff
+ ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1))
+ '()
+ pcontext))
+ ((equal? style 'piano-cautionary)
+ (set-accidentals-properties #f
+ `(Staff ,(make-accidental-rule 'same-octave 0))
+ `(Staff ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1)
+ GrandStaff
+ ,(make-accidental-rule 'any-octave 0)
+ ,(make-accidental-rule 'same-octave 1))
+ pcontext))
+
+ ;; do not set localKeySignature when a note alterated differently from
+ ;; localKeySignature is found.
+ ;; Causes accidentals to be printed at every note instead of
+ ;; remembered for the duration of a measure.
+ ;; accidentals not being remembered, causing accidentals always to
+ ;; be typeset relative to the time signature
+ ((equal? style 'forget)
+ (set-accidentals-properties '()
+ `(Staff ,(make-accidental-rule 'same-octave -1))
+ '()
+ context))
+ ;; Do not reset the key at the start of a measure. Accidentals will be
+ ;; printed only once and are in effect until overridden, possibly many
+ ;; measures later.
+ ((equal? style 'no-reset)
+ (set-accidentals-properties '()
+ `(Staff ,(make-accidental-rule 'same-octave #t))
+ '()
+ context))
+ (else
+ (ly:warning (_ "unknown accidental style: ~S") style)
+ (make-sequential-music '()))))))