SrcSpanHack.hs

-- ---------------------------------------------------------------------
-- Horrible hack for dealing with some things still having a SrcSpan,
-- not an Anchor.

{-
A SrcSpan is defined as

data SrcSpan =
    RealSrcSpan !RealSrcSpan !(Maybe BufSpan)  -- See Note [Why Maybe BufPos]
  | UnhelpfulSpan !UnhelpfulSpanReason

data BufSpan =
  BufSpan { bufSpanStart, bufSpanEnd :: {-# UNPACK #-} !BufPos }
  deriving (Eq, Ord, Show)

newtype BufPos = BufPos { bufPos :: Int }


We use the BufPos to encode a delta, using bufSpanStart for the line,
and bufSpanEnd for the col.

To be absolutely sure, we make the delta versions use -ve values.

-}

hackSrcSpanToAnchor :: SrcSpan -> Anchor
hackSrcSpanToAnchor (UnhelpfulSpan _) = error "hackSrcSpanToAnchor"
hackSrcSpanToAnchor (RealSrcSpan rs Nothing) = Anchor rs UnchangedAnchor
hackSrcSpanToAnchor (RealSrcSpan rs (Just (BufSpan (BufPos s) (BufPos e))))
  = if s <= 0 && e <= 0
    then Anchor rs (MovedAnchor (deltaPos (-s) (-e)))
    else Anchor rs UnchangedAnchor

hackAnchorToSrcSpan :: Anchor -> SrcSpan
hackAnchorToSrcSpan (Anchor rs UnchangedAnchor) = RealSrcSpan rs Nothing
hackAnchorToSrcSpan (Anchor rs (MovedAnchor dp))
  = RealSrcSpan rs (Just (BufSpan (BufPos s) (BufPos e)))
  where
    s = - (getDeltaLine dp)
    e = - (deltaColumn dp)