resolve merge

[lilypond.git] / ly / chord-repetition-init.ly

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+%%% -*- Mode: Scheme -*-
+\version "2.14.0"
+%{
+
+The following functions define the chord repetition behavior, and may
+be invoked by the user to customize it.
+
+ly:parser-set-repetition-symbol
+  set the chord repetition shortcut.
+  `q' is the default value set in this file.
+
+ly:parser-set-repetition-function
+
+  set the function that is invoked when a chord repetition symbol
+  is encountered by the parser: a four argument function
+  (previous-chord, location, duration, list of articulations) which is
+  supposed to return a new chord.
+  `default-repeat-chord' is the default function set in this file.
+  `tab-repeat-chord' may be used in tablatures to preserve the string information.
+%}
+
+#(define-public ((make-repeat-chord-function chord-element-types note-articulation-types)
+                 previous-chord location duration articulations)
+   "Make a chord repetition function.
+The returned functions copies the notes from @var{previous-chord} into a new chord.
+Chord elements, which type is found in @var{chord-element-types}, are copied into
+the new chord. Note articulations, which type is found in @var{note-articulation-types},
+are also copied. All other events are not copied into the new chord."
+   (define (filter-events events event-types)
+     (filter (lambda (event)
+              (and (memq (ly:music-property event 'name) event-types) event))
+            events))
+   ;; If previous-chord has an length property, then it means that it
+   ;; has been processed by a music iterator.  In other words, the chord
+   ;; has been memorized from an other music block, which is certainly not
+   ;; what the user has intended, as anywy the result will be buggy.
+   ;; In that case, raise a warning.
+   (if (not (and (ly:music? previous-chord)
+                (null? (ly:music-property previous-chord 'length))))
+       (ly:input-message location
+                        (_ "No memorized chord in music block before chord repetition")))
+   ;; Instead of copying the previous chord, then removing the
+   ;; undesired elements (like articulations), a new empty chord is built.
+   ;; Then, the pitch found in the previous chord are added to the new
+   ;; chord, without any "decoration" (e.g. cautionary accidentals,
+   ;; fingerings, text scripts, articulations).  Only the events of types
+   ;; given in `chord-elements-types' and `note-articulation-types' are
+   ;; copied from the original chord elements and note articulations,
+   ;; respectively.
+   (let ((elements (ly:music-property (ly:music-deep-copy previous-chord) 'elements)))
+     (make-music
+      'EventChord
+      'origin location
+      'elements (append!
+                 (map (lambda (note)
+                        (let ((new-note (make-music 'NoteEvent
+                                                    'origin location
+                                                    'pitch (ly:music-property note 'pitch)
+                                                    'duration duration))
+                              (articulations
+                               (filter-events (ly:music-property note 'articulations)
+                                              note-articulation-types)))
+                          (if (not (null? articulations))
+                              (set! (ly:music-property new-note 'articulations)
+                                    articulations))
+                          new-note))
+                      (filter-events elements '(NoteEvent)))
+                 (filter-events elements chord-element-types)
+                 articulations))))
+
+#(define-public default-repeat-chord
+   (make-repeat-chord-function '() '()))
+
+#(define-public tab-repeat-chord
+   (make-repeat-chord-function '(StringNumberEvent) '(StringNumberEvent)))
+
+% default settings
+#(ly:parser-set-repetition-symbol parser 'q)
+#(ly:parser-set-repetition-function parser default-repeat-chord)