new undo system

Also enables undoing when working with node input arrays

app/undo/undostack.cpp

@@ -20,15 +20,109 @@
 
 #include "undostack.h"
 
+#include <QCoreApplication>
+
 namespace olive {
 
-void UndoStack::pushIfHasChildren(QUndoCommand *command)
+const int UndoStack::kMaxUndoCommands = 200;
+
+UndoStack::UndoStack()
 {
-  if (command->childCount() > 0) {
+  undo_action_ = new QAction();
+  connect(undo_action_, &QAction::triggered, this, &UndoStack::undo);
+
+  redo_action_ = new QAction();
+  connect(redo_action_, &QAction::triggered, this, &UndoStack::redo);
+
+  UpdateActions();
+}
+
+UndoStack::~UndoStack()
+{
+  clear();
+
+  delete undo_action_;
+  delete redo_action_;
+}
+
+void UndoStack::pushIfHasChildren(MultiUndoCommand *command)
+{
+  if (command->child_count() > 0) {
     push(command);
   } else {
     delete command;
   }
 }
 
+void UndoStack::push(UndoCommand *command)
+{
+  command->redo_and_set_modified();
+  commands_.push_back(command);
+
+  if (commands_.size() > kMaxUndoCommands) {
+    delete commands_.front();
+    commands_.pop_front();
+  }
+
+  if (CanRedo()) {
+    for (auto it=undone_commands_.cbegin(); it!=undone_commands_.cend(); it++) {
+      delete (*it);
+    }
+    undone_commands_.clear();
+  }
+
+  UpdateActions();
+}
+
+void UndoStack::undo()
+{
+  if (CanUndo()) {
+    // Undo most recently done command
+    commands_.back()->undo_and_set_modified();
+
+    // Place at the front of the "undone commands" list
+    undone_commands_.push_front(commands_.back());
+
+    // Remove undone command from the commands list
+    commands_.pop_back();
+
+    // Update actions
+    UpdateActions();
+  }
+}
+
+void UndoStack::redo()
+{
+  if (CanRedo()) {
+    // Redo most recently undone command
+    undone_commands_.front()->redo_and_set_modified();
+
+    // Place at the back of the done commands list
+    commands_.push_back(undone_commands_.front());
+
+    // Remove done command from undone list
+    undone_commands_.pop_front();
+
+    // Update actions
+    UpdateActions();
+  }
+}
+
+void UndoStack::clear()
+{
+  for (auto it=commands_.cbegin(); it!=commands_.cend(); it++) {
+    delete (*it);
+  }
+  commands_.clear();
+}
+
+void UndoStack::UpdateActions()
+{
+  undo_action_->setEnabled(CanUndo());
+  redo_action_->setEnabled(CanRedo());
+
+  undo_action_->setText(QCoreApplication::translate("UndoStack", "Undo %1").arg(CanUndo() ? commands_.back()->name() : QString()));
+  redo_action_->setText(QCoreApplication::translate("UndoStack", "Redo %1").arg(CanRedo() ? undone_commands_.front()->name() : QString()));
+}
+
 }