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% Extra custom functions
% -------------------------------------------------------------------------

% Alternative chords

#(define (pitches-bass-inversion-context-list music context)
"Creates a list containing relevant pitches, bass, inversion and context to
serve as argument for `ignatzek-chord-names', derived from @var{music}
"
  (let* (;; work on a copy of `music', warranting not to change it
         (m-add (ly:music-deep-copy music))
         (ev-notes-orig (event-chord-notes m-add))
         ;; if chord is an inversion some pitches are below root, in this case
         ;; 'octavation-property is set.
         ;; reset pitch of them
         ;; TODO this is an ugly hack, find better method
         (ev-notes
           (map
             (lambda (m)
               (if (and (not (null? (ly:music-property m 'octavation)))
                        (= (ly:music-property m 'octavation) -1))
                   (begin
                     (ly:music-set-property! m 'pitch
                       (ly:pitch-transpose
                         (ly:music-property m 'pitch)
                         (ly:make-pitch 1 0 0)))
                      m)
                   m))
             ev-notes-orig))
         ;; sort the ptches ascending as expected by `ignatzek-chord-names'
         (ev-pitches
           (sort
             (map (lambda (m) (ly:music-property m 'pitch)) ev-notes)
             ly:pitch<?))
         ;; get bass
         (bass-note
             (filter
               (lambda (m)
                 (not (null? (ly:music-property m 'bass))))
               ev-notes))
         (bass-pitch
           (if (not (null? bass-note))
               (ly:music-property (car bass-note) 'pitch)
               '()))
         ;; get inversion
         (inversion-note
           (filter
             (lambda (m)
               (not (null? (ly:music-property m 'inversion))))
             ev-notes))
         (inversion-pitch
           (if (not (null? inversion-note))
               (ly:music-property (car inversion-note) 'pitch)
               '()))
         ;; TODO why is this needed?
         (in-pitches
           (if (null? inversion-pitch)
               (delq bass-pitch ev-pitches)
               ev-pitches)))

    (list in-pitches bass-pitch inversion-pitch context)))

altChords =
#(define-music-function (m1 m2)(ly:music? ly:music?)
"Return the default ChordName of @var{m1}, with an added parenthesized ChordName
derived from @var{m2}"
#{
   \applyOutput ChordNames.ChordName
     #(lambda (g ctx p)
        (let ((main-text (ly:grob-property g 'text))
              (alt-text
                (apply
                  ignatzek-chord-names
                  (pitches-bass-inversion-context-list m2 ctx))))
         (ly:grob-set-property! g 'text
           #{
             \markup
               { $main-text \hspace #0.4 \fontsize #-3 \parenthesize $alt-text }
           #})))
   $m1
#})

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