Define UndoManager::VisitStates

src/ProjectHistory.cpp

@@ -173,6 +173,6 @@ void ProjectHistory::SetStateTo(unsigned int n, bool doAutosave)
    auto &undoManager = UndoManager::Get( project );
 
    undoManager.SetStateTo(n,
-      [this, doAutosave]( const UndoState &state ){
-         PopState(state, doAutosave); } );
+      [this, doAutosave]( const UndoStackElem &elem ){
+         PopState(elem.state, doAutosave); } );
 }

src/UndoManager.cpp

@@ -48,24 +48,6 @@ wxDEFINE_EVENT(EVT_UNDO_RESET, wxCommandEvent);
 
 using SampleBlockID = long long;
 
-struct UndoStackElem {
-
-   UndoStackElem(std::shared_ptr<TrackList> &&tracks_,
-      const TranslatableString &description_,
-      const TranslatableString &shortDescription_,
-      const SelectedRegion &selectedRegion_,
-      const std::shared_ptr<Tags> &tags_)
-      : state(std::move(tracks_), tags_, selectedRegion_)
-      , description(description_)
-      , shortDescription(shortDescription_)
-   {
-   }
-
-   UndoState state;
-   TranslatableString description;
-   TranslatableString shortDescription;
-};
-
 static const AudacityProject::AttachedObjects::RegisteredFactory key{
    [](AudacityProject &project)
       { return std::make_unique<UndoManager>( project ); }
@@ -370,7 +352,7 @@ void UndoManager::SetStateTo(unsigned int n, const Consumer &consumer)
    lastAction = {};
    mayConsolidate = false;
 
-   consumer( stack[current]->state );
+   consumer( *stack[current] );
 
    // wxWidgets will own the event object
    mProject.QueueEvent( safenew wxCommandEvent{ EVT_UNDO_RESET } );
@@ -385,7 +367,7 @@ void UndoManager::Undo(const Consumer &consumer)
    lastAction = {};
    mayConsolidate = false;
 
-   consumer( stack[current]->state );
+   consumer( *stack[current] );
 
    // wxWidgets will own the event object
    mProject.QueueEvent( safenew wxCommandEvent{ EVT_UNDO_OR_REDO } );
@@ -413,12 +395,39 @@ void UndoManager::Redo(const Consumer &consumer)
    lastAction = {};
    mayConsolidate = false;
 
-   consumer( stack[current]->state );
+   consumer( *stack[current] );
 
    // wxWidgets will own the event object
    mProject.QueueEvent( safenew wxCommandEvent{ EVT_UNDO_OR_REDO } );
 }
 
+void UndoManager::VisitStates( const Consumer &consumer, bool newestFirst )
+{
+   auto fn = [&]( decltype(stack[0]) &ptr ){ consumer( *ptr ); };
+   if (newestFirst)
+      std::for_each(stack.rbegin(), stack.rend(), fn);
+   else
+      std::for_each(stack.begin(), stack.end(), fn);
+}
+
+void UndoManager::VisitStates(
+   const Consumer &consumer, size_t begin, size_t end )
+{
+   auto size = stack.size();
+   if (begin < end) {
+      end = std::min(end, size);
+      for (auto ii = begin; ii < end; ++ii)
+         consumer(*stack[ii]);
+   }
+   else {
+      if (size == 0)
+         return;
+      begin = std::min(begin, size - 1);
+      for (auto ii = begin; ii > end; --ii)
+         consumer(*stack[ii]);
+   }
+}
+
 bool UndoManager::UnsavedChanges() const
 {
    return (saved != current);

src/UndoManager.h

@@ -76,7 +76,6 @@ class Tags;
 class Track;
 class TrackList;
 
-struct UndoStackElem;
 struct UndoState {
    UndoState(std::shared_ptr<TrackList> &&tracks_,
       const std::shared_ptr<Tags> &tags_,
@@ -89,6 +88,24 @@ struct UndoState {
    SelectedRegion selectedRegion; // by value
 };
 
+struct UndoStackElem {
+
+   UndoStackElem(std::shared_ptr<TrackList> &&tracks_,
+      const TranslatableString &description_,
+      const TranslatableString &shortDescription_,
+      const SelectedRegion &selectedRegion_,
+      const std::shared_ptr<Tags> &tags_)
+      : state(std::move(tracks_), tags_, selectedRegion_)
+      , description(description_)
+      , shortDescription(shortDescription_)
+   {
+   }
+
+   UndoState state;
+   TranslatableString description;
+   TranslatableString shortDescription;
+};
+
 using UndoStack = std::vector <std::unique_ptr<UndoStackElem>>;
 
 using SpaceArray = std::vector <unsigned long long> ;
@@ -150,11 +167,18 @@ class AUDACITY_DLL_API UndoManager final
    // These functions accept a callback that uses the state,
    // and then they send to the project EVT_UNDO_RESET or EVT_UNDO_OR_REDO when
    // that has finished.
-   using Consumer = std::function< void( const UndoState & ) >;
+   using Consumer = std::function< void( const UndoStackElem & ) >;
    void SetStateTo(unsigned int n, const Consumer &consumer);
    void Undo(const Consumer &consumer);
    void Redo(const Consumer &consumer);
 
+   //! Give read-only access to all states
+   void VisitStates( const Consumer &consumer, bool newestFirst );
+   //! Visit a specified range of states
+   /*! end is exclusive; visit newer states first if end < begin */
+   void VisitStates(
+      const Consumer &consumer, size_t begin, size_t end );
+
    bool UndoAvailable();
    bool RedoAvailable();
 

src/menus/EditMenus.cpp

@@ -183,8 +183,8 @@ void OnUndo(const CommandContext &context)
    }
 
    undoManager.Undo(
-      [&]( const UndoState &state ){
-         ProjectHistory::Get( project ).PopState( state ); } );
+      [&]( const UndoStackElem &elem ){
+         ProjectHistory::Get( project ).PopState( elem.state ); } );
 
    auto t = *tracks.Selected().begin();
    if (!t)
@@ -213,8 +213,8 @@ void OnRedo(const CommandContext &context)
    }
 
    undoManager.Redo(
-      [&]( const UndoState &state ){
-         ProjectHistory::Get( project ).PopState( state ); } );
+      [&]( const UndoStackElem &elem ){
+         ProjectHistory::Get( project ).PopState( elem.state ); } );
 
    auto t = *tracks.Selected().begin();
    if (!t)