It's hard to maintain this information when using begin() and end() so rather than wrapping the iterators, just check each time IsComposite() is called since it doesn't happen _that_ often. Just don't call IsComposite() often.

stepmania/src/NoteData.cpp

@@ -21,7 +21,6 @@ NoteData::NoteData()
 
 void NoteData::Init()
 {
-	m_bComposite = false;
 	ClearAll();
 	m_TapNotes = vector<TrackMap>();	// ensure that the memory is freed
 }
@@ -37,6 +36,16 @@ void NoteData::SetNumTracks( int iNewNumTracks )
 	m_TapNotes.resize( iNewNumTracks );
 }
 
+bool NoteData::IsComposite() const
+{
+	for( int track = 0; track < GetNumTracks(); ++track )
+	{
+		FOREACHM_CONST( int, TapNote, m_TapNotes[track], tn )
+			if( tn->second.pn != PLAYER_INVALID )
+				return true;
+	}
+	return false;
+}
 
 /* Clear [rowBegin,rowEnd). */
 void NoteData::ClearRangeForTrack( int rowBegin, int rowEnd, int iTrack )

stepmania/src/NoteData.h

@@ -30,8 +30,6 @@ private:
 	// There's no point in inserting empty notes into the map.
 	// Any blank space in the map is defined to be empty.
 	vector<TrackMap>	m_TapNotes;
-	// This NoteData comprises multiple NoteDatas.
-	bool			m_bComposite;
 
 public:
 	NoteData();
@@ -40,8 +38,7 @@ public:
 	
 	int GetNumTracks() const { return m_TapNotes.size(); }
 	void SetNumTracks( int iNewNumTracks );
-	bool IsComposite() const { return m_bComposite; }
-	void SetComposite( bool b ) { m_bComposite = b; }
+	bool IsComposite() const;
 
 	/* Return the note at the given track and row.  Row may be out of
 	 * range; pretend the song goes on with TAP_EMPTYs indefinitely. */

stepmania/src/NoteDataUtil.cpp

@@ -239,7 +239,7 @@ static void LoadFromSMNoteDataStringWithPlayer( NoteData& out, const RString &sS
 	
 }
 
-void NoteDataUtil::LoadFromSMNoteDataString( NoteData &out, const RString &sSMNoteData_ )
+void NoteDataUtil::LoadFromSMNoteDataString( NoteData &out, const RString &sSMNoteData_, bool bComposite )
 {
 	//
 	// Load note data
@@ -263,10 +263,8 @@ void NoteDataUtil::LoadFromSMNoteDataString( NoteData &out, const RString &sSMNo
 	
 	/* Clear notes, but keep the same number of tracks. */
 	int iNumTracks = out.GetNumTracks();
-	bool bComposite = out.IsComposite();
 	out.Init();
 	out.SetNumTracks( iNumTracks );
-	out.SetComposite( bComposite );
 	
 	if( !bComposite )
 	{

stepmania/src/NoteDataUtil.h

@@ -17,7 +17,7 @@ struct RadarValues;
 namespace NoteDataUtil
 {
 	NoteType GetSmallestNoteTypeForMeasure( const NoteData &n, int iMeasureIndex );
-	void LoadFromSMNoteDataString( NoteData &out, const RString &sSMNoteData );
+	void LoadFromSMNoteDataString( NoteData &out, const RString &sSMNoteData, bool bComposite );
 	void GetSMNoteDataString( const NoteData &in, RString &notes_out );
 	void SplitCompositeNoteData( const NoteData &in, vector<NoteData> &out );
 	void LoadTransformedSlidingWindow( const NoteData &in, NoteData &out, int iNewNumTracks );

stepmania/src/Steps.cpp

@@ -225,11 +225,11 @@ void Steps::Decompress() const
 	else
 	{
 		// load from compressed
+		bool bComposite = m_StepsType == STEPS_TYPE_DANCE_ROUTINE;
 		m_bNoteDataIsFilled = true;
 		m_pNoteData->SetNumTracks( GameManager::StepsTypeToNumTracks(m_StepsType) );
-		m_pNoteData->SetComposite( m_StepsType == STEPS_TYPE_DANCE_ROUTINE );
 
-		NoteDataUtil::LoadFromSMNoteDataString( *m_pNoteData, m_sNoteDataCompressed );
+		NoteDataUtil::LoadFromSMNoteDataString( *m_pNoteData, m_sNoteDataCompressed, bComposite );
 	}
 }