Soloing

generator/scales/selection.py

@@ -56,7 +56,7 @@ def following_indices(timeline: tuple[generator.scales.timeline.ChordSpan, ...])
     result[index] = result[index + 1] if same else index + 1
   return result
 
-def select(timeline: tuple[generator.scales.timeline.ChordSpan, ...], solo: generator.scales.timeline.Solo, library: generator.scales.library.Library) -> tuple[Choice, ...]:
+def select(timeline: tuple[generator.scales.timeline.ChordSpan, ...], solo: generator.scales.timeline.Solo, library: generator.scales.library.Library, *, retained: tuple = ()) -> tuple[Choice, ...]:
   collections = library.collections()
   following = following_indices(timeline)
   rows, layers = [], []
@@ -77,6 +77,9 @@ def select(timeline: tuple[generator.scales.timeline.ChordSpan, ...], solo: gene
     if target.pitches == home.pitches:
       target = home
     required = set(generator.harmony.pitch_classes(span.chord)) if span.chord else set()
+    for start, end, pitches in retained:
+      if start < span.end and end > span.start:
+        required.update(pitches)
     options = [target if scale.pitches == target.pitches else home if scale.pitches == home.pitches else scale for scale in collections if required <= scale.pitches] if span.chord else []
     options = options or [None]
     layer = []