1 files changed, 161 insertions, 0 deletions
diff --git a/indra/llui/llundo.cpp b/indra/llui/llundo.cpp
new file mode 100644
index 0000000000..61e17c1879
--- /dev/null
+++ b/indra/llui/llundo.cpp
@@ -0,0 +1,161 @@
+/** 
+ * @file llundo.cpp
+ * @brief LLUndo class
+ *
+ * Copyright (c) 2001-$CurrentYear$, Linden Research, Inc.
+ * $License$
+ */
+
+// Generic interface for undo/redo circular buffer
+
+#include "linden_common.h"
+
+#include "llundo.h"
+#include "llerror.h"
+
+
+// TODO:
+// implement doubly linked circular list for ring buffer
+// this will allow us to easily change the size of an undo buffer on the fly
+
+//-----------------------------------------------------------------------------
+// LLUndoBuffer()
+//-----------------------------------------------------------------------------
+LLUndoBuffer::LLUndoBuffer( LLUndoAction (*create_func()), S32 initial_count )
+{
+	mNextAction = 0;
+	mLastAction = 0;
+	mFirstAction = 0;
+	mOperationID = 0;
+
+	mNumActions = initial_count;	
+
+	mActions = new LLUndoAction *[initial_count];
+
+	//initialize buffer with actions
+	for (S32 i = 0; i < initial_count; i++)
+	{
+		mActions[i] = create_func();
+		if (!mActions[i])
+		{
+			llerrs << "Unable to create action for undo buffer" << llendl;
+		}
+	}
+}
+
+//-----------------------------------------------------------------------------
+// ~LLUndoBuffer()
+//-----------------------------------------------------------------------------
+LLUndoBuffer::~LLUndoBuffer()
+{
+	for (S32 i = 0; i < mNumActions; i++)
+	{
+		delete mActions[i];
+	}
+
+	delete [] mActions;
+}
+
+//-----------------------------------------------------------------------------
+// getNextAction()
+//-----------------------------------------------------------------------------
+LLUndoAction *LLUndoBuffer::getNextAction(BOOL setClusterBegin)
+{
+	LLUndoAction *nextAction = mActions[mNextAction];
+
+	if (setClusterBegin)
+	{
+		mOperationID++;
+	}
+	mActions[mNextAction]->mClusterID = mOperationID;
+
+	mNextAction = (mNextAction + 1) % mNumActions;
+	mLastAction = mNextAction;
+
+	if (mNextAction == mFirstAction)
+	{
+		mActions[mFirstAction]->cleanup();
+		mFirstAction = (mFirstAction + 1) % mNumActions;
+	}
+
+	return nextAction;
+}
+
+//-----------------------------------------------------------------------------
+// undoAction()
+//-----------------------------------------------------------------------------
+BOOL LLUndoBuffer::undoAction()
+{
+	if (!canUndo())
+	{
+		return FALSE;
+	}
+
+	S32 prevAction = (mNextAction + mNumActions - 1) % mNumActions;
+
+	while(mActions[prevAction]->mClusterID == mOperationID)
+	{
+		// go ahead and decrement action index
+		mNextAction = prevAction;
+
+		// undo this action
+		mActions[mNextAction]->undo();
+
+		// we're at the first action, so we don't know if we've actually undid everything
+		if (mNextAction == mFirstAction)
+		{
+			mOperationID--;
+			return FALSE;
+		}
+
+		// do wrap-around of index, but avoid negative numbers for modulo operator
+		prevAction = (mNextAction + mNumActions - 1) % mNumActions;
+	}
+
+	mOperationID--;
+
+	return TRUE;
+}
+
+//-----------------------------------------------------------------------------
+// redoAction()
+//-----------------------------------------------------------------------------
+BOOL LLUndoBuffer::redoAction()
+{
+	if (!canRedo())
+	{
+		return FALSE;
+	}
+
+	mOperationID++;
+
+	while(mActions[mNextAction]->mClusterID == mOperationID)
+	{
+		if (mNextAction == mLastAction)
+		{
+			return FALSE;
+		}
+
+		mActions[mNextAction]->redo();
+
+		// do wrap-around of index
+		mNextAction = (mNextAction + 1) % mNumActions;
+	}
+
+	return TRUE;
+}
+
+//-----------------------------------------------------------------------------
+// flushActions()
+//-----------------------------------------------------------------------------
+void LLUndoBuffer::flushActions()
+{
+	for (S32 i = 0; i < mNumActions; i++)
+	{
+		mActions[i]->cleanup();
+	}
+	mNextAction = 0;
+	mLastAction = 0;
+	mFirstAction = 0;
+	mOperationID = 0;
+}