1 files changed, 52 insertions, 0 deletions
diff --git a/indra/llui/llundo.h b/indra/llui/llundo.h
new file mode 100644
index 0000000000..8d0428ad3e
--- /dev/null
+++ b/indra/llui/llundo.h
@@ -0,0 +1,52 @@
+/** 
+ * @file llundo.h
+ * @brief LLUndo class header file
+ *
+ * Copyright (c) 2000-$CurrentYear$, Linden Research, Inc.
+ * $License$
+ */
+
+#ifndef LL_LLUNDO_H
+#define LL_LLUNDO_H
+
+class LLUndoAction
+{
+	friend class LLUndoBuffer;
+protected:
+	S32		mClusterID;
+protected:
+	LLUndoAction(): mClusterID(0) {};
+	virtual ~LLUndoAction(){};
+
+public:
+	static LLUndoAction *create() { return NULL; }
+
+	virtual void undo() = 0;
+	virtual void redo() = 0;
+	virtual void cleanup() {};
+};
+
+class LLUndoBuffer
+{
+protected:
+	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
+
+public:
+	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();
+};
+
+#endif //LL_LLUNDO_H