+(define-session-public chordmodifiers '())
+
+(define-public (construct-chord-elements root duration modifications)
+ "Build a chord on root using modifiers in @var{modifications}.
+@code{NoteEvents} have duration @var{duration}.
+
+Notes: Natural 11 is left from chord if not explicitly specified.
+
+Entry point for the parser."
+ (let* ((flat-mods (flatten-list modifications))
+ (base-chord (stack-thirds (ly:make-pitch 0 4 0) the-canonical-chord))
+ (complete-chord '())
+ (bass #f)
+ (inversion #f)
+ (lead-mod #f)
+ (explicit-11 #f)
+ (explicit-2/4 #f)
+ (omit-3 #f)
+ (start-additions #t))
+
+ (define (interpret-inversion chord mods)
+ "Read /FOO part. Side effect: INVERSION is set."
+ (if (and (> (length mods) 1) (eq? (car mods) 'chord-slash))
+ (begin
+ (set! inversion (cadr mods))
+ (set! mods (cddr mods))))
+ (interpret-bass chord mods))
+
+ (define (interpret-bass chord mods)
+ "Read /+FOO part. Side effect: BASS is set."
+ (if (and (> (length mods) 1) (eq? (car mods) 'chord-bass))
+ (begin
+ (set! bass (cadr mods))
+ (set! mods (cddr mods))))
+ (if (pair? mods)
+ (ly:parser-error
+ (format #f (_ "Spurious garbage following chord: ~A") mods)))
+ chord)
+
+ (define (interpret-removals chord mods)
+ (define (inner-interpret chord mods)
+ (if (and (pair? mods) (ly:pitch? (car mods)))
+ (inner-interpret (remove-step (+ 1 (ly:pitch-steps (car mods))) chord)
+ (cdr mods))
+ (interpret-inversion chord mods)))
+ (if (and (pair? mods) (eq? (car mods) 'chord-caret))
+ (inner-interpret chord (cdr mods))
+ (interpret-inversion chord mods)))
+
+ (define (interpret-additions chord mods)
+ "Interpret additions. TODO: should restrict modifier use?"
+ (cond ((null? mods) chord)
+ ((ly:pitch? (car mods))
+ (case (pitch-step (car mods))
+ ((11) (set! explicit-11 #t))
+ ((2 4) (set! explicit-2/4 #t))
+ ((3) (set! omit-3 #f)))
+ (interpret-additions (cons (car mods) (remove-step (pitch-step (car mods)) chord))
+ (cdr mods)))
+ ((procedure? (car mods))
+ (interpret-additions ((car mods) chord)
+ (cdr mods)))
+ (else (interpret-removals chord mods))))
+
+ (define (pitch-octavated-strictly-below p root)
+ "return P, but octavated, so it is below ROOT"
+ (ly:make-pitch (+ (ly:pitch-octave root)
+ (if (> (ly:pitch-notename root)
+ (ly:pitch-notename p))
+ 0 -1))
+ (ly:pitch-notename p)
+ (ly:pitch-alteration p)))
+
+ (define (process-inversion complete-chord)
+ "Take out inversion from COMPLETE-CHORD, and put it at the bottom.
+Return (INVERSION . REST-OF-CHORD).
+
+Side effect: put original pitch in INVERSION.
+If INVERSION is not in COMPLETE-CHORD, it will be set as a BASS, overriding
+the bass specified.
+
+"
+ (let* ((root (car complete-chord))
+ (inv? (lambda (y)
+ (and (= (ly:pitch-notename y)
+ (ly:pitch-notename inversion))
+ (= (ly:pitch-alteration y)
+ (ly:pitch-alteration inversion)))))
+ (rest-of-chord (remove inv? complete-chord))
+ (inversion-candidates (filter inv? complete-chord))
+ (down-inversion (pitch-octavated-strictly-below inversion root)))
+ (if (pair? inversion-candidates)
+ (set! inversion (car inversion-candidates))
+ (begin
+ (set! bass inversion)
+ (set! inversion #f)))
+ (if inversion
+ (cons down-inversion rest-of-chord)
+ rest-of-chord)))
+ ;; root is always one octave too low.
+ ;; something weird happens when this is removed,
+ ;; every other chord is octavated. --hwn... hmmm.
+ (set! root (ly:pitch-transpose root (ly:make-pitch 1 0 0)))
+ ;; skip the leading : , we need some of the stuff following it.
+ (if (pair? flat-mods)
+ (if (eq? (car flat-mods) 'chord-colon)
+ (set! flat-mods (cdr flat-mods))
+ (set! start-additions #f)))
+ ;; remember modifier
+ (if (and (pair? flat-mods) (procedure? (car flat-mods)))
+ (begin
+ (set! lead-mod (car flat-mods))
+ (set! flat-mods (cdr flat-mods))))
+ ;; extract first number if present, and build pitch list.
+ (if (and (pair? flat-mods)
+ (ly:pitch? (car flat-mods))
+ (not (eq? lead-mod sus-modifier)))
+ (begin
+ (cond ((= (pitch-step (car flat-mods)) 11)
+ (set! explicit-11 #t))
+ ((equal? (ly:make-pitch 0 4 0) (car flat-mods))
+ (set! omit-3 #t)))
+ (set! base-chord
+ (stack-thirds (car flat-mods) the-canonical-chord))
+ (set! flat-mods (cdr flat-mods))))
+ ;; apply modifier
+ (if (procedure? lead-mod)
+ (set! base-chord (lead-mod base-chord)))
+ (set! complete-chord
+ (if start-additions
+ (interpret-additions base-chord flat-mods)
+ (interpret-removals base-chord flat-mods)))
+ ;; if sus has been given neither 2 or 4, we add 4.
+ (if (and (eq? lead-mod sus-modifier)
+ (not explicit-2/4))
+ (set! complete-chord (cons (ly:make-pitch 0 4 0) complete-chord)))
+ (set! complete-chord (sort complete-chord ly:pitch<?))
+ ;; If natural 11 + natural 3 is present, but not given explicitly,
+ ;; we remove the 11.
+ (if (and (not explicit-11)
+ (get-step 11 complete-chord)
+ (get-step 3 complete-chord)
+ (= 0 (ly:pitch-alteration (get-step 11 complete-chord)))
+ (= 0 (ly:pitch-alteration (get-step 3 complete-chord))))
+ (set! complete-chord (remove-step 11 complete-chord)))
+ ;; if omit-3 has been set (and not reset by an explicit 3
+ ;; somewhere), we remove the 3
+ (if omit-3
+ (set! complete-chord (remove-step 3 complete-chord)))
+ ;; must do before processing inversion/bass, since they are
+ ;; not relative to the root.
+ (set! complete-chord (map (lambda (x) (ly:pitch-transpose x root))
+ complete-chord))
+ (if inversion
+ (set! complete-chord (process-inversion complete-chord)))
+ (if bass
+ (set! bass (pitch-octavated-strictly-below bass root)))
+ (if #f
+ (begin
+ (write-me "\n*******\n" flat-mods)
+ (write-me "root: " root)
+ (write-me "base chord: " base-chord)
+ (write-me "complete chord: " complete-chord)
+ (write-me "inversion: " inversion)
+ (write-me "bass: " bass)))
+ (if inversion
+ (make-chord-elements (cdr complete-chord) bass duration (car complete-chord)
+ inversion)
+ (make-chord-elements complete-chord bass duration #f #f))))
+
+
+(define (make-chord-elements pitches bass duration inversion original-inv-pitch)
+ "Make EventChord with notes corresponding to PITCHES, BASS and
+DURATION, and INVERSION. Notes above INVERSION are transposed downward
+along with the inversion as long as they end up below at least one
+non-inverted note."
+ (define (make-note-ev pitch . rest)
+ (apply make-music 'NoteEvent
+ 'duration duration
+ 'pitch pitch
+ rest))
+ (cond (inversion
+ (let* ((octavation (- (ly:pitch-octave inversion)
+ (ly:pitch-octave original-inv-pitch)))
+ (down (ly:make-pitch octavation 0 0)))
+ (define (invert p) (ly:pitch-transpose down p))
+ (define (make-inverted p . rest)
+ (apply make-note-ev (invert p) 'octavation octavation rest))
+ (receive (uninverted high)
+ (span (lambda (p) (ly:pitch<? p original-inv-pitch))
+ pitches)
+ (receive (invertible rest)
+ (if (null? uninverted)
+ ;; The following line caters for
+ ;; inversions "on the root", turning
+ ;; f/f into <f a' c''> rather than <f a c'>
+ ;; or <f' a' c''>
+ (values '() high)
+ (span (lambda (p)
+ (ly:pitch<? (invert p) (car uninverted)))
+ high))
+ (cons (make-inverted original-inv-pitch 'inversion #t)
+ (append (if bass (list (make-note-ev bass 'bass #t)) '())
+ (map make-inverted invertible)
+ (map make-note-ev uninverted)
+ (map make-note-ev rest)))))))
+ (bass (cons (make-note-ev bass 'bass #t)
+ (map make-note-ev pitches)))
+ (else (map make-note-ev pitches))))
+
+;;;;;;;;;;;;;;;;
+;; chord modifiers change the pitch list.
+
+(define (aug-modifier pitches)
+ (set! pitches (replace-step (ly:make-pitch 0 4 SHARP) pitches))
+ (replace-step (ly:make-pitch 0 2 0) pitches))
+
+(define (minor-modifier pitches)
+ (replace-step (ly:make-pitch 0 2 FLAT) pitches))
+
+(define (maj7-modifier pitches)