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/**
* @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;
}
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