mapping.hs

mappingFromDiff :: BS.ByteString -> BS.ByteString -> PositionMapping
mappingFromDiff (BS.lines -> old) (BS.lines -> new) = PositionMapping (PositionDelta (lookupPos lnew old2new) (lookupPos lold new2old))
  where
    diff = getDiff old new

    (!old2new, !new2old) = go diff 0 0

    lnew = lines new
    lold = lines old

    lookupPos :: [(Int,Maybe Int)] -> Position -> PositionResult Position
    lookupPos max xs (Position line col) = go 0 xs
      where
        go prev [] = PositionRange (Position (prev+1) 0) (Position max 0)
        go prev ((a,b):xs) = _

    go [] _ _ = ([],[])
    go (Both _ _ : xs) lold lnew = bimap  ((lold,Just lnew) :) ((lnew,Just lold) :) $ go xs (lold+1) (lnew+1)
    go (First _  : xs) lold lnew = first  ((lold,Nothing) :) $ go xs (lold+1) lnew
    go (Second _ : xs) lold lnew = second ((lnew,Nothing) :) $ go xs lold (lnew+1)