public void CloseGroup()
{
if (groupStart == null)
{
Debug.Assert(false);
throw new InvalidOperationException();
}
if (groupStart == records)
{
// delete empty undo group to eliminate no-op entries on user's undo stack
records = records.Next;
return;
}
if (clearRedo)
{
textEdit.redo = null;
}
SelectionUndoRecord selection = new SelectionUndoRecord(textEdit);
selection.Next = records;
records = selection;
GroupEndUndoRecord end = new GroupEndUndoRecord(groupStart);
end.Next = records;
records = end;
groupStart = null;
}
public IDisposable OpenGroup()
{
// defer this until close group - avoids clearing redo if group was empty
//if (clearRedo)
//{
// textEdit.redo = null;
//}
if (groupStart == null)
{
groupStart = new GroupStartUndoRecord();
groupStart.Next = records;
records = groupStart;
return new UndoGroupCloser(this);
}
else
{
return null;
}
}
public GroupEndUndoRecord(GroupStartUndoRecord start)
{
this.Start = start;
}
