added nodes.

nodes/services/ntxundostack.h

@@ -0,0 +1,56 @@
+#ifndef NTX_UNDO_STACK_H
+#define NTX_UNDO_STACK_H
+
+#include <ntxicommand.h>
+#include <vector>
+#include <functional>
+
+namespace ntx
+{
+
+  class NtxUndoStack
+  {
+  public:
+
+    NtxUndoStack();
+    ~NtxUndoStack() = default;
+
+    NtxUndoStack(const NtxUndoStack&) = delete;
+    NtxUndoStack& operator=(const NtxUndoStack&) = delete;
+
+    void push(NtxCommandUPtr command);
+    
+    bool canUndo() const;
+    bool canRedo() const;
+    
+    void undo();
+    void redo();
+    
+    int index() const;
+    int count() const;
+    
+    NtxString undoText() const;
+    NtxString redoText() const;
+    
+    void clear();
+    void setClean();
+    bool isClean() const;
+    
+    void setUndoLimit(int limit);
+    int undoLimit() const;
+    
+    const NtxICommand* command(int index) const;
+
+  private:
+
+    std::vector<NtxCommandUPtr> m_commands;
+    int m_index;
+    int m_cleanIndex;
+    int m_undoLimit;
+
+    void checkUndoLimit();
+  };
+
+} // namespace ntx
+
+#endif // NTX_UNDO_STACK_H