http://www.google.com/codesearch http://www.google.com/codesearch allows them, so it is doable. It may not be efficient for larger datasets and large numbers o

http://www.google.com/codesearch http://www.google.com/codesearch allows them, so it is doable. It may not be efficient for larger datasets and large numbers of users, but that need not be a problem for the search engine owners, as they could just take their sweet time in returning results.