presto-spi/src/main/java/io/prestosql/spi/function/RankingWindowFunction.java/RankingWindowFunction/processRow
class RankingWindowFunction:    @Override
    public final void processRow(BlockBuilder output, int peerGroupStart, int peerGroupEnd, int frameStart, int frameEnd)
    {
        boolean newPeerGroup = false;
        if (peerGroupStart != currentPeerGroupStart) {
            currentPeerGroupStart = peerGroupStart;
            newPeerGroup = true;
        }

        int peerGroupCount = (peerGroupEnd - peerGroupStart) + 1;

        processRow(output, newPeerGroup, peerGroupCount, currentPosition);

        currentPosition++;
    }