llundo.h

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#ifndef LL_LLUNDO_H
#define LL_LLUNDO_H


class LLUndoBuffer
{
public:
        class LLUndoAction
        {
                friend class LLUndoBuffer;
        public:
                virtual void undo() = 0;
                virtual void redo() = 0;
                virtual void cleanup() {};
        protected:
                LLUndoAction(): mClusterID(0) {};
                virtual ~LLUndoAction(){};
        private:
                S32             mClusterID;
        };

        LLUndoBuffer( LLUndoAction (*create_func()), S32 initial_count );
        virtual ~LLUndoBuffer();

        LLUndoAction *getNextAction(BOOL setClusterBegin = TRUE);
        BOOL undoAction();
        BOOL redoAction();
        BOOL canUndo() { return (mNextAction != mFirstAction); }
        BOOL canRedo() { return (mNextAction != mLastAction); }

        void flushActions();

private:
        LLUndoAction **mActions;        // array of pointers to undoactions
        S32                     mNumActions;    // total number of actions in ring buffer
        S32                     mNextAction;    // next action to perform undo/redo on
        S32                     mLastAction;    // last action actually added to undo buffer
        S32                     mFirstAction;   // beginning of ring buffer (don't undo any further)
        S32                     mOperationID;   // current operation id, for undoing and redoing in clusters
};

#endif //LL_LLUNDO_H

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