alex-3.2.4: data/AlexWrapper-basic

{-# LINE 1 "templates/wrappers.hs" #-}
-- -----------------------------------------------------------------------------
-- Alex wrapper code.
--
-- This code is in the PUBLIC DOMAIN; you may copy it freely and use
-- it for any purpose whatsoever.






import Data.Word (Word8)
















import Data.Char (ord)
import qualified Data.Bits

-- | Encode a Haskell String to a list of Word8 values, in UTF8 format.
utf8Encode :: Char -> [Word8]
utf8Encode = map fromIntegral . go . ord
 where
  go oc
   | oc <= 0x7f       = [oc]

   | oc <= 0x7ff      = [ 0xc0 + (oc `Data.Bits.shiftR` 6)
                        , 0x80 + oc Data.Bits..&. 0x3f
                        ]

   | oc <= 0xffff     = [ 0xe0 + (oc `Data.Bits.shiftR` 12)
                        , 0x80 + ((oc `Data.Bits.shiftR` 6) Data.Bits..&. 0x3f)
                        , 0x80 + oc Data.Bits..&. 0x3f
                        ]
   | otherwise        = [ 0xf0 + (oc `Data.Bits.shiftR` 18)
                        , 0x80 + ((oc `Data.Bits.shiftR` 12) Data.Bits..&. 0x3f)
                        , 0x80 + ((oc `Data.Bits.shiftR` 6) Data.Bits..&. 0x3f)
                        , 0x80 + oc Data.Bits..&. 0x3f
                        ]



type Byte = Word8

-- -----------------------------------------------------------------------------
-- The input type
















































































-- -----------------------------------------------------------------------------
-- Token positions

-- `Posn' records the location of a token in the input text.  It has three
-- fields: the address (number of chacaters preceding the token), line number
-- and column of a token within the file. `start_pos' gives the position of the
-- start of the file and `eof_pos' a standard encoding for the end of file.
-- `move_pos' calculates the new position after traversing a given character,
-- assuming the usual eight character tab stops.














-- -----------------------------------------------------------------------------
-- Default monad
















































































































-- -----------------------------------------------------------------------------
-- Monad (with ByteString input)







































































































-- -----------------------------------------------------------------------------
-- Basic wrapper


type AlexInput = (Char,[Byte],String)

alexInputPrevChar :: AlexInput -> Char
alexInputPrevChar (c,_,_) = c

-- alexScanTokens :: String -> [token]
alexScanTokens str = go ('\n',[],str)
  where go inp__@(_,_bs,s) =
          case alexScan inp__ 0 of
                AlexEOF -> []
                AlexError _ -> error "lexical error"
                AlexSkip  inp__' _ln     -> go inp__'
                AlexToken inp__' len act -> act (take len s) : go inp__'

alexGetByte :: AlexInput -> Maybe (Byte,AlexInput)
alexGetByte (c,(b:bs),s) = Just (b,(c,bs,s))
alexGetByte (_,[],[])    = Nothing
alexGetByte (_,[],(c:s)) = case utf8Encode c of
                             (b:bs) -> Just (b, (c, bs, s))
                             [] -> Nothing



-- -----------------------------------------------------------------------------
-- Basic wrapper, ByteString version
































-- -----------------------------------------------------------------------------
-- Posn wrapper

-- Adds text positions to the basic model.













-- -----------------------------------------------------------------------------
-- Posn wrapper, ByteString version














-- -----------------------------------------------------------------------------
-- GScan wrapper

-- For compatibility with previous versions of Alex, and because we can.