alex-3.2.5: 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 = uncurry (:) . utf8Encode'

utf8Encode' :: Char -> (Word8, [Word8])
utf8Encode' c = case go (ord c) of
                  (x, xs) -> (fromIntegral x, map fromIntegral xs)
 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.














-- -----------------------------------------------------------------------------
-- Monad (default and 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))



-- -----------------------------------------------------------------------------
-- 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.