Implement filtering JsonParser (using JSONpath maybe)

For efficient yet convenient processing of information from streams, it would be very useful to implement a filtering JsonParser; something that is given another parser to read data from, determines what to include and what not, and produce valid subset of information as a new logical stream. This stream has to maintain valid JSON structure; that is, all included non-structure entries should have same parentage (enclosing arrays, objects) as the source stream.