alex-3.2.4: data/AlexWrapper-posn-bytestring

{-# 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.Int (Int64)
import qualified Data.Char
import qualified Data.ByteString.Lazy     as ByteString
import qualified Data.ByteString.Internal as ByteString (w2c)




































type Byte = Word8

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






















type AlexInput = (AlexPosn,     -- current position,
                  Char,         -- previous char
                  ByteString.ByteString,        -- current input string
                  Int64)           -- bytes consumed so far

ignorePendingBytes :: AlexInput -> AlexInput
ignorePendingBytes i = i   -- no pending bytes when lexing bytestrings

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

alexGetByte :: AlexInput -> Maybe (Byte,AlexInput)
alexGetByte (p,_,cs,n) =
    case ByteString.uncons cs of
        Nothing -> Nothing
        Just (b, cs') ->
            let c   = ByteString.w2c b
                p'  = alexMove p c
                n'  = n+1
            in p' `seq` cs' `seq` n' `seq` Just (b, (p', c, cs',n'))






































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


data AlexPosn = AlexPn !Int !Int !Int
        deriving (Eq,Show)

alexStartPos :: AlexPosn
alexStartPos = AlexPn 0 1 1

alexMove :: AlexPosn -> Char -> AlexPosn
alexMove (AlexPn a l c) '\t' = AlexPn (a+1)  l     (((c+alex_tab_size-1) `div` alex_tab_size)*alex_tab_size+1)
alexMove (AlexPn a l _) '\n' = AlexPn (a+1) (l+1)   1
alexMove (AlexPn a l c) _    = AlexPn (a+1)  l     (c+1)


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
















































































































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







































































































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

























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
































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

-- Adds text positions to the basic model.













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


--alexScanTokens :: ByteString.ByteString -> [token]
alexScanTokens str0 = go (alexStartPos,'\n',str0,0)
  where go inp__@(pos,_,str,n) =
          case alexScan inp__ 0 of
                AlexEOF -> []
                AlexError ((AlexPn _ line column),_,_,_) -> error $ "lexical error at line " ++ (show line) ++ ", column " ++ (show column)
                AlexSkip  inp__' _len       -> go inp__'
                AlexToken inp__'@(_,_,_,n') _ act ->
                  act pos (ByteString.take (n'-n) str) : go inp__'



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

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