Fix issue #1335: voice numbers written in MusicXML must be unique…

music21/musicxml/m21ToXml.py

@@ -1514,6 +1514,8 @@ def parse(self):
             # before attempting to identify and count instruments
             self._populatePartExporterList()
             self.groupsToJoin = self.joinableGroups()
+            self.setPartExporterStaffGroups()
+            self.renumberVoicesWithinStaffGroups()
             self.parsePartlikeScore()
         else:
             self.parseFlatScore()
@@ -1728,6 +1730,60 @@ def parseFlatScore(self):
         pp.parse()
         self.partExporterList.append(pp)
 
+    def setPartExporterStaffGroups(self):
+        '''
+        Figures out the containing StaffGroup for every PartExporter that has one.
+
+        Called automatically by .parse()
+        '''
+        for partExp in self.partExporterList:
+            joinableGroup = None
+            for sg in self.groupsToJoin:
+                if partExp.stream in sg:
+                    joinableGroup = sg
+                    break
+
+            partExp.staffGroup = joinableGroup
+
+    def renumberVoicesWithinStaffGroups(self):
+        '''
+        Renumbers voices (as appropriate) in each StaffGroup, so that
+        voices have unique numbers across the entire group.
+
+        Called automatically by .parse()
+        '''
+        staffGroupsProcessed: t.List = []
+        for partExp in self.partExporterList:
+            if partExp.staffGroup is None:
+                # no staffGroup to process
+                continue
+
+            if partExp.staffGroup in staffGroupsProcessed:
+                # we already processed this one
+                continue
+
+            # renumber the voices in this StaffGroup
+            staffGroupScore = stream.Score(partExp.staffGroup.getSpannedElements())
+            measuresStream = staffGroupScore.recurse().getElementsByClass(stream.Measure).stream()
+            nextVoiceId: int = 1
+            for measureStack in OffsetIterator(measuresStream):
+                for m in measureStack:
+                    for v in m[stream.Voice]:
+                        if not isinstance(v.id, int):
+                            # it's not an integer, leave it as is, and don't move nextVoiceId
+                            continue
+                        elif v.id < defaults.minIdNumberToConsiderMemoryLocation:
+                            # it's a low integer, leave it as is, and jump nextVoiceId to v.id + 1
+                            nextVoiceId = v.id + 1
+                        else:
+                            # it's a memory location, set v.id to nextVoiceId and increment
+                            v.id = nextVoiceId
+                            nextVoiceId += 1
+
+            # remember we did this one, so we don't do it again
+            staffGroupsProcessed.append(partExp.staffGroup)
+
+
     def postPartProcess(self):
         '''
         calls .joinPartStaffs() from the
@@ -2612,6 +2668,9 @@ def __init__(self,
         # has changed
         self.lastDivisions = None
 
+        # The staffGroup to which this part belongs (if it belongs to one)
+        self.staffGroup: t.Optional[layout.StaffGroup] = None
+
         self.spannerBundle = partObj.spannerBundle
 
     def parse(self):
@@ -3084,8 +3143,8 @@ def __init__(self,
         self.measureOffsetStart = 0.0
         self.offsetInMeasure = 0.0
         self.currentVoiceId: t.Optional[int] = None
-        self.nextFreeVoiceNumber = 1
-        self.nextArpeggioNumber = 1
+        self.nextFreeVoiceNumber: int = 1
+        self.nextArpeggioNumber: int = 1
         self.arpeggioNumbers: t.Dict[expressions.ArpeggioMarkSpanner, int] = {}
 
         self.rbSpanners: t.List[spanner.RepeatBracket] = []  # repeatBracket spanners
@@ -3161,7 +3220,10 @@ def parseFlatElements(self, m, *, backupAfterwards=False):
             m: stream.Voice
             if isinstance(m.id, int) and m.id < defaults.minIdNumberToConsiderMemoryLocation:
                 voiceId = m.id
+                self.nextFreeVoiceNumber = voiceId + 1
             elif isinstance(m.id, int):
+                # This voice id is actually a memory location, so we need to change it
+                # to a low number so it can be used in MusicXML.
                 voiceId = self.nextFreeVoiceNumber
                 self.nextFreeVoiceNumber += 1
             else:

music21/musicxml/partStaffExporter.py

@@ -899,6 +899,12 @@ def testJoinPartStaffsB(self):
         s.insert(0, layout.StaffGroup([ps1, ps2]))
         root = self.getET(s)
         notes = root.findall('.//note')
+
+        # since there are no voices in either PartStaff, the voice number of each note
+        # should be the same as the staff number.
+        for mxNote in notes:
+            self.assertEqual(mxNote.find('voice').text, mxNote.find('staff').text)
+
         forward = root.find('.//forward')
         backup = root.find('.//backup')
         amountToBackup = (
@@ -955,6 +961,62 @@ def testJoinPartStaffsD(self):
         self.assertEqual(len(measures), 2)
         self.assertEqual(len(notes), 12)
 
+    def testJoinPartStaffsD2(self):
+        '''
+        Add measures and voices and check for unique voice numbers across the StaffGroup.
+        '''
+        from music21 import layout
+        from music21 import note
+        s = stream.Score()
+        ps1 = stream.PartStaff()
+        m1 = stream.Measure()
+        ps1.insert(0, m1)
+        v1 = stream.Voice()
+        v2 = stream.Voice()
+        m1.insert(0, v1)
+        m1.insert(0, v2)
+        v1.repeatAppend(note.Note('C4'), 4)
+        v2.repeatAppend(note.Note('E4'), 4)
+        ps1.makeNotation(inPlace=True)  # makeNotation to freeze notation
+
+        ps2 = stream.PartStaff()
+        m2 = stream.Measure()
+        ps2.insert(0, m2)
+        v3 = stream.Voice()
+        v4 = stream.Voice()
+        m2.insert(0, v3)
+        m2.insert(0, v4)
+        v3.repeatAppend(note.Note('C3'), 4)
+        v4.repeatAppend(note.Note('G3'), 4)
+        ps2.makeNotation(inPlace=True)  # makeNotation to freeze notation
+
+        s.insert(0, ps2)
+        s.insert(0, ps1)
+        s.insert(0, layout.StaffGroup([ps1, ps2]))
+        root = self.getET(s)
+        measures = root.findall('.//measure')
+        notes = root.findall('.//note')
+        # from music21.musicxml.helpers import dump
+        # dump(root)
+        self.assertEqual(len(measures), 1)
+        self.assertEqual(len(notes), 16)
+
+        # check those voice and staff numbers
+        for mxNote in notes:
+            mxPitch = mxNote.find('pitch')
+            if mxPitch.find('step').text == 'C' and mxPitch.find('octave').text == '4':
+                self.assertEqual(mxNote.find('voice').text, '1')
+                self.assertEqual(mxNote.find('staff').text, '1')
+            elif mxPitch.find('step').text == 'E' and mxPitch.find('octave').text == '4':
+                self.assertEqual(mxNote.find('voice').text, '2')
+                self.assertEqual(mxNote.find('staff').text, '1')
+            elif mxPitch.find('step').text == 'C' and mxPitch.find('octave').text == '3':
+                self.assertEqual(mxNote.find('voice').text, '3')
+                self.assertEqual(mxNote.find('staff').text, '2')
+            elif mxPitch.find('step').text == 'G' and mxPitch.find('octave').text == '3':
+                self.assertEqual(mxNote.find('voice').text, '4')
+                self.assertEqual(mxNote.find('staff').text, '2')
+
     def testJoinPartStaffsE(self):
         '''
         Measure numbers existing only in certain PartStaffs: don't collapse together

music21/musicxml/test_m21ToXml.py

@@ -146,11 +146,49 @@ def testLowVoiceNumbers(self):
         v1.id = 234
         xmlOut = self.getXml(m)
         self.assertIn('<voice>234</voice>', xmlOut)
-        self.assertIn('<voice>1</voice>', xmlOut)  # is v2 now!
+        self.assertIn('<voice>235</voice>', xmlOut)
         v2.id = 'hello'
         xmlOut = self.getXml(m)
         self.assertIn('<voice>hello</voice>', xmlOut)
 
+    def testVoiceNumberOffsetsThreeStaffsInGroup(self):
+        n1_1 = note.Note()
+        v1_1 = stream.Voice([n1_1])
+        m1_1 = stream.Measure([v1_1])
+        n1_2 = note.Note()
+        v1_2 = stream.Voice([n1_2])
+        m1_2 = stream.Measure([v1_2])
+        ps1 = stream.PartStaff([m1_1, m1_2])
+
+        n2_1 = note.Note()
+        v2_1 = stream.Voice([n2_1])
+        m2_1 = stream.Measure([v2_1])
+        n2_2 = note.Note()
+        v2_2 = stream.Voice([n2_2])
+        m2_2 = stream.Measure([v2_2])
+        ps2 = stream.PartStaff([m2_1, m2_2])
+
+        n3_1 = note.Note()
+        v3_1 = stream.Voice([n3_1])
+        m3_1 = stream.Measure([v3_1])
+        n3_2 = note.Note()
+        v3_2 = stream.Voice([n3_2])
+        m3_2 = stream.Measure([v3_2])
+        ps3 = stream.PartStaff([m3_1, m3_2])
+
+        s = stream.Score([ps1, ps2, ps3])
+        staffGroup = layout.StaffGroup([ps1, ps2, ps3])
+        s.insert(0, staffGroup)
+
+        tree = self.getET(s)
+        # helpers.dump(tree)
+        mxNotes = tree.findall('part/measure/note')
+        for mxNote in mxNotes:
+            voice = mxNote.find('voice')
+            staff = mxNote.find('staff')
+            # Because there is one voice per staff/measure, voicenum == staffnum
+            self.assertEqual(voice.text, staff.text)
+
     def testCompositeLyrics(self):
         xmlDir = common.getSourceFilePath() / 'musicxml' / 'lilypondTestSuite'
         fp = xmlDir / '61l-Lyrics-Elisions-Syllables.xml'