ly/chord-repetition-init.ly

   1 %%% -*- Mode: Scheme -*-
   2 \version "2.13.17"
   3 %{
   4
   5 The following functions define the chord repetition behavior, and may
   6 be invoked by the user to customize it.
   7
   8 ly:parser-set-repetition-symbol
   9   set the chord repetition shortcut.
  10   `q' is the default value set in this file.
  11
  12 ly:parser-set-repetition-function
  13
  14   set the function that is invoked when a chord repetition symbol
  15   is encountered by the parser: a four argument function
  16   (previous-chord, location, duration, list of articulations) which is
  17   supposed to return a new chord.
  18   `default-repeat-chord' is the default function set in this file.
  19   `tab-repeat-chord' may be used in tablatures to preserve the string information.
  20 %}
  21
  22 #(define-public ((make-repeat-chord-function chord-element-types note-articulation-types)
  23                  previous-chord location duration articulations)
  24    "Make a chord repetition function.
  25 The returned functions copies the notes from @var{previous-chord} into a new chord.
  26 Chord elements, which type is found in @var{chord-element-types}, are copied into
  27 the new chord. Note articulations, which type is found in @var{note-articulation-types},
  28 are also copied. All other events are not copied into the new chord."
  29    (define (filter-events events event-types)
  30      (filter (lambda (event)
  31                (and (memq (ly:music-property event 'name) event-types) event))
  32              events))
  33    ;; If previous-chord has an length property, then it means that it
  34    ;; has been processed by a music iterator.  In other words, the chord
  35    ;; has been memorized from an other music block, which is certainly not
  36    ;; what the user has intended, as anywy the result will be buggy.
  37    ;; In that case, raise a warning.
  38    (if (not (and (ly:music? previous-chord)
  39                  (null? (ly:music-property previous-chord 'length))))
  40        (ly:input-message location
  41                          (_ "No memorized chord in music block before chord repetition")))
  42    ;; Instead of copying the previous chord, then removing the
  43    ;; undesired elements (like articulations), a new empty chord is built.
  44    ;; Then, the pitch found in the previous chord are added to the new
  45    ;; chord, without any "decoration" (e.g. cautionary accidentals,
  46    ;; fingerings, text scripts, articulations).  Only the events of types
  47    ;; given in `chord-elements-types' and `note-articulation-types' are
  48    ;; copied from the original chord elements and note articulations,
  49    ;; respectively.
  50    (let ((elements (ly:music-property (ly:music-deep-copy previous-chord) 'elements)))
  51      (make-music
  52       'EventChord
  53       'origin location
  54       'elements (append!
  55                  (map (lambda (note)
  56                         (let ((new-note (make-music 'NoteEvent
  57                                                     'origin location
  58                                                     'pitch (ly:music-property note 'pitch)
  59                                                     'duration duration))
  60                               (articulations
  61                                (filter-events (ly:music-property note 'articulations)
  62                                               note-articulation-types)))
  63                           (if (not (null? articulations))
  64                               (set! (ly:music-property new-note 'articulations)
  65                                     articulations))
  66                           new-note))
  67                       (filter-events elements '(NoteEvent)))
  68                  (filter-events elements chord-element-types)
  69                  articulations))))
  70
  71 #(define-public default-repeat-chord
  72    (make-repeat-chord-function '() '()))
  73
  74 #(define-public tab-repeat-chord
  75    (make-repeat-chord-function '(StringNumberEvent) '(StringNumberEvent)))
  76
  77 % default settings
  78 #(ly:parser-set-repetition-symbol parser 'q)
  79 #(ly:parser-set-repetition-function parser default-repeat-chord)