Unfortunately the oneworld itinerary data is organized by segment, not by flight #.. so calculating direct flights is a bit tricky.

I can find all flights A->B and B->C with the same flight number, but there can be issues with overlapping dates or flights on different dates, etc.

I've been working on a Oneworld itinerary validator tool, it works pretty well so far (open jaws confuse it) except some of the transit rules. I'm also attempting to integrate it with the oneworld itinerary data, to make sure that the itinerary can be done with existing flights.

Also on a side note I've been working on an award ticket mileage calculator, it will show mileage required for one-way/round-trip/point-to-point itineraries on a number of airlines. Sounds like something people might be interested in?

Eg. enter Round Trip: dallas to sydney

returns: (Y,J,F requirements)
aa (all airlines): 75,125,145
aa (oneworld): 100,130,180
united (star): 60,90,120
qantas (ba/aa/qf): 80,160,200
qantas (oneworld): 100,175,250
delta: 100,150,200

etc.