Replace toScaleDegree with parseSpelledPitchOrScaleDegree to support chord charts written in key signature or numbers.

src/pco_chordspkg/ast.nim

@@ -186,12 +186,12 @@ proc parseChord*(
 
     let bass =
       if m.get.captures.contains(4) and m.get.captures[4].len > 0:
-        some(toScaleDegree(ctx.curKey, parseSpelledPitch(m.get.captures[4])))
+        some(parseSpelledPitchOrScaleDegree(ctx.curKey, m.get.captures[4]))
       else: none[ScaleDegree]()
 
     return some(ChordChartChord(
       original: some(chordValue),
-      root: toScaleDegree(ctx.curKey, parseSpelledPitch(m.get.captures[0])),
+      root: parseSpelledPitchOrScaleDegree(ctx.curKey, m.get.captures[0]),
       flavor: flavor,
       bass: bass))
 

src/pco_chordspkg/notation.nim

@@ -314,6 +314,16 @@ func toScaleDegree*(k: Key, sp: SpelledPitch): ScaleDegree =
   ]#
 
 
+func parseSpelledPitchOrScaleDegree*(key: Key, str: string): ScaleDegree =
+  try:
+    let pitch =parseSpelledPitch(str)
+    return toScaleDegree(key, pitch)
+  except:
+    try: return parseScaleDegree(str)
+    except:
+      raise newException(ValueError,
+        str & " is not a recognized pitch or scale degree")
+
 
 func transpose*(k: Key, steps: int): Key =
   Key(