Define and use copy and move for TrackList, simplifying recording code

src/Track.cpp

@@ -713,6 +713,49 @@ TrackList::TrackList(bool destructorDeletesTracks)
    tail = NULL;
 }
 
+TrackList::TrackList(const TrackList &that)
+{
+   DoAssign(that);
+}
+
+TrackList& TrackList::operator= (const TrackList &that)
+{
+   if (this != &that) {
+      this->Clear(mDestructorDeletesTracks);
+      DoAssign(that);
+   }
+   return *this;
+}
+
+TrackList::TrackList(TrackList &&that)
+{
+   Swap(that);
+}
+
+TrackList &TrackList::operator= (TrackList &&that)
+{
+   if (this != &that) {
+      this->Clear(mDestructorDeletesTracks);
+      Swap(that);
+   }
+   return *this;
+}
+
+void TrackList::DoAssign(const TrackList &that)
+{
+   mDestructorDeletesTracks = true;
+   TrackListConstIterator it(&that);
+   for (const Track *track = it.First(); track; track = it.Next())
+      Add(track->Duplicate());
+}
+
+void TrackList::Swap(TrackList &that)
+{
+   std::swap(mDestructorDeletesTracks, that.mDestructorDeletesTracks);
+   std::swap(head, that.head);
+   std::swap(tail, that.tail);
+}
+
 TrackList::~TrackList()
 {
    Clear(mDestructorDeletesTracks);
@@ -1025,7 +1068,7 @@ bool TrackList::CanMoveDown(Track * t) const
 // The complication is that the tracks are stored in a single
 // linked list, and pairs of tracks are marked only by a flag
 // in one of the tracks.
-void TrackList::Swap(TrackListNode * s1, TrackListNode * s2)
+void TrackList::SwapNodes(TrackListNode * s1, TrackListNode * s2)
 {
    Track *link;
    Track *source[4];
@@ -1092,7 +1135,7 @@ bool TrackList::MoveUp(Track * t)
    if (t) {
       Track *p = GetPrev(t, true);
       if (p) {
-         Swap((TrackListNode *)p->GetNode(), (TrackListNode *)t->GetNode());
+         SwapNodes((TrackListNode *)p->GetNode(), (TrackListNode *)t->GetNode());
          return true;
       }
    }
@@ -1105,7 +1148,7 @@ bool TrackList::MoveDown(Track * t)
    if (t) {
       Track *n = GetNext(t, true);
       if (n) {
-         Swap((TrackListNode *)t->GetNode(), (TrackListNode *)n->GetNode());
+         SwapNodes((TrackListNode *)t->GetNode(), (TrackListNode *)n->GetNode());
          return true;
       }
    }

src/Track.h

@@ -394,6 +394,18 @@ class AUDACITY_DLL_API TrackList final : public wxEvtHandler
    // Create an empty TrackList
    TrackList(bool destructorDeletesTracks = false);
 
+   // Allow copy -- a deep copy that duplicates all tracks
+   TrackList(const TrackList &that);
+   TrackList &operator= (const TrackList &that);
+
+   // Allow move
+   TrackList(TrackList &&that);
+   TrackList& operator= (TrackList&&);
+
+   // Move is defined in terms of Swap
+   void Swap(TrackList &that);
+
+
    // Destructor
    virtual ~TrackList();
 
@@ -473,11 +485,13 @@ class AUDACITY_DLL_API TrackList final : public wxEvtHandler
 #endif
 
  private:
+   void DoAssign(const TrackList &that);
+       
    void RecalcPositions(const TrackListNode *node);
    void UpdatedEvent(const TrackListNode *node);
    void ResizedEvent(const TrackListNode *node);
 
-   void Swap(TrackListNode * s1, TrackListNode * s2);
+   void SwapNodes(TrackListNode * s1, TrackListNode * s2);
 
    TrackListNode *head;
    TrackListNode *tail;

src/toolbars/ControlToolBar.cpp

@@ -799,8 +799,8 @@ void ControlToolBar::OnRecord(wxCommandEvent &evt)
    SetRecord(true, mRecord->WasShiftDown());
 
    if (p) {
-      TrackList *t = p->GetTracks();
-      TrackListIterator it(t);
+      TrackList *trackList = p->GetTracks();
+      TrackListIterator it(trackList);
       if(it.First() == NULL)
          mRecord->SetShift(false);
       double t0 = p->GetSel0();
@@ -818,7 +818,7 @@ void ControlToolBar::OnRecord(wxCommandEvent &evt)
       gPrefs->Read(wxT("/AudioIO/Duplex"), &duplex, true);
 
       if(duplex){
-         playbackTracks = t->GetWaveTrackArray(false);
+         playbackTracks = trackList->GetWaveTrackArray(false);
 #ifdef EXPERIMENTAL_MIDI_OUT
          midiTracks = t->GetNoteTrackArray(false);
 #endif
@@ -832,7 +832,7 @@ void ControlToolBar::OnRecord(wxCommandEvent &evt)
 
       // If SHIFT key was down, the user wants append to tracks
       int recordingChannels = 0;
-      TrackList tracksCopy(true);
+      TrackList tracksCopy{};
       bool tracksCopied = false;
       bool shifted = mRecord->WasShiftDown();
       if (shifted) {
@@ -879,12 +879,7 @@ void ControlToolBar::OnRecord(wxCommandEvent &evt)
                if (t1 < t0) {
                   if (!tracksCopied) {
                      tracksCopied = true;
-                     TrackListIterator iter(t);
-                     Track *trk = iter.First();
-                     while (trk) {
-                        tracksCopy.Add(trk->Duplicate());
-                        trk = iter.Next();
-                     }
+                     tracksCopy = *trackList;
                   }
 
                   WaveTrack *newTrack = p->GetTrackFactory()->NewWaveTrack();
@@ -985,7 +980,7 @@ void ControlToolBar::OnRecord(wxCommandEvent &evt)
          // we add the tracks where recording is done into now. We remove them
          // later if starting the stream fails
          for (unsigned int i = 0; i < newRecordingTracks.size(); i++)
-            t->Add(newRecordingTracks[i]);
+            trackList->Add(newRecordingTracks[i]);
       }
 
       //Automated Input Level Adjustment Initialization
@@ -1010,22 +1005,13 @@ void ControlToolBar::OnRecord(wxCommandEvent &evt)
       else {
          if (shifted) {
             // Restore the tracks to remove any inserted silence
-            if (tracksCopied) {
-               t->Clear(true);
-               TrackListIterator iter(&tracksCopy);
-               Track *trk = iter.First();
-               while (trk)
-               {
-                  Track *tmp = trk;
-                  trk = iter.RemoveCurrent();
-                  t->Add(tmp);
-               }
-            }
+            if (tracksCopied)
+               *trackList = std::move(tracksCopy);
          }
          else {
             // msmeyer: Delete recently added tracks if opening stream fails
             for (unsigned int i = 0; i < newRecordingTracks.size(); i++) {
-               t->Remove(newRecordingTracks[i]);
+               trackList->Remove(newRecordingTracks[i]);
                delete newRecordingTracks[i];
             }
          }