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+{-# LANGUAGE BangPatterns, GADTs, OverloadedStrings, RecordWildCards #-}
+-- |
+-- Module : Data.Attoparsec.ByteString.Internal
+-- Copyright : Bryan O'Sullivan 2007-2014
+-- License : BSD3
+--
+-- Maintainer : bos@serpentine.com
+-- Stability : experimental
+-- Portability : unknown
+--
+-- Simple, efficient parser combinators for 'ByteString' strings,
+-- loosely based on the Parsec library.
+
+module Data.Attoparsec.ByteString.Internal
+ (
+ -- * Parser types
+ Parser
+ , Result
+
+ -- * Running parsers
+ , parse
+ , parseOnly
+
+ -- * Combinators
+ , module Data.Attoparsec.Combinator
+
+ -- * Parsing individual bytes
+ , satisfy
+ , satisfyWith
+ , anyWord8
+ , skip
+ , word8
+ , notWord8
+
+ -- ** Lookahead
+ , peekWord8
+ , peekWord8'
+
+ -- ** Byte classes
+ , inClass
+ , notInClass
+
+ -- * Parsing more complicated structures
+ , storable
+
+ -- * Efficient string handling
+ , skipWhile
+ , string
+ , stringTransform
+ , take
+ , scan
+ , runScanner
+ , takeWhile
+ , takeWhile1
+ , takeTill
+
+ -- ** Consume all remaining input
+ , takeByteString
+ , takeLazyByteString
+
+ -- * Utilities
+ , endOfLine
+ , endOfInput
+ , match
+ , atEnd
+ ) where
+
+import Control.Applicative ((<|>), (<$>))
+import Control.Monad (when)
+import Data.Attoparsec.ByteString.Buffer (Buffer, buffer)
+import Data.Attoparsec.ByteString.FastSet (charClass, memberWord8)
+import Data.Attoparsec.Combinator ((<?>))
+import Data.Attoparsec.Internal
+import Data.Attoparsec.Internal.Fhthagn (inlinePerformIO)
+import Data.Attoparsec.Internal.Types hiding (Parser, Failure, Success)
+import Data.ByteString (ByteString)
+import Data.Word (Word8)
+import Foreign.ForeignPtr (withForeignPtr)
+import Foreign.Ptr (castPtr, minusPtr, plusPtr)
+import Foreign.Storable (Storable(peek, sizeOf))
+import Prelude hiding (getChar, succ, take, takeWhile)
+import qualified Data.Attoparsec.ByteString.Buffer as Buf
+import qualified Data.Attoparsec.Internal.Types as T
+import qualified Data.ByteString as B8
+import qualified Data.ByteString.Char8 as B
+import qualified Data.ByteString.Internal as B
+import qualified Data.ByteString.Lazy as L
+import qualified Data.ByteString.Unsafe as B
+
+type Parser = T.Parser ByteString
+type Result = IResult ByteString
+type Failure r = T.Failure ByteString Buffer r
+type Success a r = T.Success ByteString Buffer a r
+
+-- | The parser @satisfy p@ succeeds for any byte for which the
+-- predicate @p@ returns 'True'. Returns the byte that is actually
+-- parsed.
+--
+-- >digit = satisfy isDigit
+-- > where isDigit w = w >= 48 && w <= 57
+satisfy :: (Word8 -> Bool) -> Parser Word8
+satisfy p = do
+ h <- peekWord8'
+ if p h
+ then advance 1 >> return h
+ else fail "satisfy"
+{-# INLINE satisfy #-}
+
+-- | The parser @skip p@ succeeds for any byte for which the predicate
+-- @p@ returns 'True'.
+--
+-- >skipDigit = skip isDigit
+-- > where isDigit w = w >= 48 && w <= 57
+skip :: (Word8 -> Bool) -> Parser ()
+skip p = do
+ h <- peekWord8'
+ if p h
+ then advance 1
+ else fail "skip"
+
+-- | The parser @satisfyWith f p@ transforms a byte, and succeeds if
+-- the predicate @p@ returns 'True' on the transformed value. The
+-- parser returns the transformed byte that was parsed.
+satisfyWith :: (Word8 -> a) -> (a -> Bool) -> Parser a
+satisfyWith f p = do
+ h <- peekWord8'
+ let c = f h
+ if p c
+ then advance 1 >> return c
+ else fail "satisfyWith"
+{-# INLINE satisfyWith #-}
+
+storable :: Storable a => Parser a
+storable = hack undefined
+ where
+ hack :: Storable b => b -> Parser b
+ hack dummy = do
+ (fp,o,_) <- B.toForeignPtr `fmap` take (sizeOf dummy)
+ return . B.inlinePerformIO . withForeignPtr fp $ \p ->
+ peek (castPtr $ p `plusPtr` o)
+
+-- | Consume @n@ bytes of input, but succeed only if the predicate
+-- returns 'True'.
+takeWith :: Int -> (ByteString -> Bool) -> Parser ByteString
+takeWith n0 p = do
+ let n = max n0 0
+ s <- ensure n
+ if p s
+ then advance n >> return s
+ else fail "takeWith"
+
+-- | Consume exactly @n@ bytes of input.
+take :: Int -> Parser ByteString
+take n = takeWith n (const True)
+{-# INLINE take #-}
+
+-- | @string s@ parses a sequence of bytes that identically match
+-- @s@. Returns the parsed string (i.e. @s@). This parser consumes no
+-- input if it fails (even if a partial match).
+--
+-- /Note/: The behaviour of this parser is different to that of the
+-- similarly-named parser in Parsec, as this one is all-or-nothing.
+-- To illustrate the difference, the following parser will fail under
+-- Parsec given an input of @\"for\"@:
+--
+-- >string "foo" <|> string "for"
+--
+-- The reason for its failure is that the first branch is a
+-- partial match, and will consume the letters @\'f\'@ and @\'o\'@
+-- before failing. In attoparsec, the above parser will /succeed/ on
+-- that input, because the failed first branch will consume nothing.
+string :: ByteString -> Parser ByteString
+string s = takeWith (B.length s) (==s)
+{-# INLINE string #-}
+
+stringTransform :: (ByteString -> ByteString) -> ByteString
+ -> Parser ByteString
+stringTransform f s = takeWith (B.length s) ((==f s) . f)
+{-# INLINE stringTransform #-}
+
+-- | Skip past input for as long as the predicate returns 'True'.
+skipWhile :: (Word8 -> Bool) -> Parser ()
+skipWhile p = go
+ where
+ go = do
+ t <- B8.takeWhile p <$> get
+ continue <- inputSpansChunks (B.length t)
+ when continue go
+{-# INLINE skipWhile #-}
+
+-- | Consume input as long as the predicate returns 'False'
+-- (i.e. until it returns 'True'), and return the consumed input.
+--
+-- This parser does not fail. It will return an empty string if the
+-- predicate returns 'True' on the first byte of input.
+--
+-- /Note/: Because this parser does not fail, do not use it with
+-- combinators such as 'Control.Applicative.many', because such
+-- parsers loop until a failure occurs. Careless use will thus result
+-- in an infinite loop.
+takeTill :: (Word8 -> Bool) -> Parser ByteString
+takeTill p = takeWhile (not . p)
+{-# INLINE takeTill #-}
+
+-- | Consume input as long as the predicate returns 'True', and return
+-- the consumed input.
+--
+-- This parser does not fail. It will return an empty string if the
+-- predicate returns 'False' on the first byte of input.
+--
+-- /Note/: Because this parser does not fail, do not use it with
+-- combinators such as 'Control.Applicative.many', because such
+-- parsers loop until a failure occurs. Careless use will thus result
+-- in an infinite loop.
+takeWhile :: (Word8 -> Bool) -> Parser ByteString
+takeWhile p = (B.concat . reverse) `fmap` go []
+ where
+ go acc = do
+ s <- B8.takeWhile p <$> get
+ continue <- inputSpansChunks (B.length s)
+ if continue
+ then go (s:acc)
+ else return (s:acc)
+{-# INLINE takeWhile #-}
+
+takeRest :: Parser [ByteString]
+takeRest = go []
+ where
+ go acc = do
+ input <- wantInput
+ if input
+ then do
+ s <- get
+ advance (B.length s)
+ go (s:acc)
+ else return (reverse acc)
+
+-- | Consume all remaining input and return it as a single string.
+takeByteString :: Parser ByteString
+takeByteString = B.concat `fmap` takeRest
+
+-- | Consume all remaining input and return it as a single string.
+takeLazyByteString :: Parser L.ByteString
+takeLazyByteString = L.fromChunks `fmap` takeRest
+
+data T s = T {-# UNPACK #-} !Int s
+
+scan_ :: (s -> [ByteString] -> Parser r) -> s -> (s -> Word8 -> Maybe s)
+ -> Parser r
+scan_ f s0 p = go [] s0
+ where
+ go acc s1 = do
+ let scanner (B.PS fp off len) =
+ withForeignPtr fp $ \ptr0 -> do
+ let start = ptr0 `plusPtr` off
+ end = start `plusPtr` len
+ inner ptr !s
+ | ptr < end = do
+ w <- peek ptr
+ case p s w of
+ Just s' -> inner (ptr `plusPtr` 1) s'
+ _ -> done (ptr `minusPtr` start) s
+ | otherwise = done (ptr `minusPtr` start) s
+ done !i !s = return (T i s)
+ inner start s1
+ bs <- get
+ let T i s' = inlinePerformIO $ scanner bs
+ !h = B.unsafeTake i bs
+ continue <- inputSpansChunks i
+ if continue
+ then go (h:acc) s'
+ else f s' (h:acc)
+{-# INLINE scan_ #-}
+
+-- | A stateful scanner. The predicate consumes and transforms a
+-- state argument, and each transformed state is passed to successive
+-- invocations of the predicate on each byte of the input until one
+-- returns 'Nothing' or the input ends.
+--
+-- This parser does not fail. It will return an empty string if the
+-- predicate returns 'Nothing' on the first byte of input.
+--
+-- /Note/: Because this parser does not fail, do not use it with
+-- combinators such as 'Control.Applicative.many', because such
+-- parsers loop until a failure occurs. Careless use will thus result
+-- in an infinite loop.
+scan :: s -> (s -> Word8 -> Maybe s) -> Parser ByteString
+scan = scan_ $ \_ chunks ->
+ case chunks of
+ [x] -> return x
+ xs -> return $! B.concat $ reverse xs
+{-# INLINE scan #-}
+
+-- | Like 'scan', but generalized to return the final state of the
+-- scanner.
+runScanner :: s -> (s -> Word8 -> Maybe s) -> Parser (ByteString, s)
+runScanner = scan_ $ \s xs -> return (B.concat (reverse xs), s)
+{-# INLINE runScanner #-}
+
+-- | Consume input as long as the predicate returns 'True', and return
+-- the consumed input.
+--
+-- This parser requires the predicate to succeed on at least one byte
+-- of input: it will fail if the predicate never returns 'True' or if
+-- there is no input left.
+takeWhile1 :: (Word8 -> Bool) -> Parser ByteString
+takeWhile1 p = do
+ (`when` demandInput) =<< endOfChunk
+ s <- B8.takeWhile p <$> get
+ let len = B.length s
+ if len == 0
+ then fail "takeWhile1"
+ else do
+ advance len
+ eoc <- endOfChunk
+ if eoc
+ then (s<>) `fmap` takeWhile p
+ else return s
+
+-- | Match any byte in a set.
+--
+-- >vowel = inClass "aeiou"
+--
+-- Range notation is supported.
+--
+-- >halfAlphabet = inClass "a-nA-N"
+--
+-- To add a literal @\'-\'@ to a set, place it at the beginning or end
+-- of the string.
+inClass :: String -> Word8 -> Bool
+inClass s = (`memberWord8` mySet)
+ where mySet = charClass s
+ {-# NOINLINE mySet #-}
+{-# INLINE inClass #-}
+
+-- | Match any byte not in a set.
+notInClass :: String -> Word8 -> Bool
+notInClass s = not . inClass s
+{-# INLINE notInClass #-}
+
+-- | Match any byte.
+anyWord8 :: Parser Word8
+anyWord8 = satisfy $ const True
+{-# INLINE anyWord8 #-}
+
+-- | Match a specific byte.
+word8 :: Word8 -> Parser Word8
+word8 c = satisfy (== c) <?> show c
+{-# INLINE word8 #-}
+
+-- | Match any byte except the given one.
+notWord8 :: Word8 -> Parser Word8
+notWord8 c = satisfy (/= c) <?> "not " ++ show c
+{-# INLINE notWord8 #-}
+
+-- | Match any byte, to perform lookahead. Returns 'Nothing' if end of
+-- input has been reached. Does not consume any input.
+--
+-- /Note/: Because this parser does not fail, do not use it with
+-- combinators such as 'Control.Applicative.many', because such
+-- parsers loop until a failure occurs. Careless use will thus result
+-- in an infinite loop.
+peekWord8 :: Parser (Maybe Word8)
+peekWord8 = T.Parser $ \t pos@(Pos pos_) more _lose succ ->
+ case () of
+ _| pos_ < Buf.length t ->
+ let !w = Buf.unsafeIndex t pos_
+ in succ t pos more (Just w)
+ | more == Complete ->
+ succ t pos more Nothing
+ | otherwise ->
+ let succ' t' pos' more' = let !w = Buf.unsafeIndex t' pos_
+ in succ t' pos' more' (Just w)
+ lose' t' pos' more' = succ t' pos' more' Nothing
+ in prompt t pos more lose' succ'
+{-# INLINE peekWord8 #-}
+
+-- | Match any byte, to perform lookahead. Does not consume any
+-- input, but will fail if end of input has been reached.
+peekWord8' :: Parser Word8
+peekWord8' = T.Parser $ \t pos more lose succ ->
+ if lengthAtLeast pos 1 t
+ then succ t pos more (Buf.unsafeIndex t (fromPos pos))
+ else let succ' t' pos' more' bs' = succ t' pos' more' $! B.unsafeHead bs'
+ in ensureSuspended 1 t pos more lose succ'
+{-# INLINE peekWord8' #-}
+
+-- | Match either a single newline character @\'\\n\'@, or a carriage
+-- return followed by a newline character @\"\\r\\n\"@.
+endOfLine :: Parser ()
+endOfLine = (word8 10 >> return ()) <|> (string "\r\n" >> return ())
+
+-- | Terminal failure continuation.
+failK :: Failure a
+failK t (Pos pos) _more stack msg = Fail (Buf.unsafeDrop pos t) stack msg
+{-# INLINE failK #-}
+
+-- | Terminal success continuation.
+successK :: Success a a
+successK t (Pos pos) _more a = Done (Buf.unsafeDrop pos t) a
+{-# INLINE successK #-}
+
+-- | Run a parser.
+parse :: Parser a -> ByteString -> Result a
+parse m s = T.runParser m (buffer s) (Pos 0) Incomplete failK successK
+{-# INLINE parse #-}
+
+-- | Run a parser that cannot be resupplied via a 'Partial' result.
+--
+-- This function does not force a parser to consume all of its input.
+-- Instead, any residual input will be discarded. To force a parser
+-- to consume all of its input, use something like this:
+--
+-- @
+--'parseOnly' (myParser 'Control.Applicative.<*' 'endOfInput')
+-- @
+parseOnly :: Parser a -> ByteString -> Either String a
+parseOnly m s = case T.runParser m (buffer s) (Pos 0) Complete failK successK of
+ Fail _ _ err -> Left err
+ Done _ a -> Right a
+ _ -> error "parseOnly: impossible error!"
+{-# INLINE parseOnly #-}
+
+get :: Parser ByteString
+get = T.Parser $ \t pos more _lose succ ->
+ succ t pos more (Buf.unsafeDrop (fromPos pos) t)
+{-# INLINE get #-}
+
+endOfChunk :: Parser Bool
+endOfChunk = T.Parser $ \t pos more _lose succ ->
+ succ t pos more (fromPos pos == Buf.length t)
+{-# INLINE endOfChunk #-}
+
+inputSpansChunks :: Int -> Parser Bool
+inputSpansChunks i = T.Parser $ \t pos_ more _lose succ ->
+ let pos = pos_ + Pos i
+ in if fromPos pos < Buf.length t || more == Complete
+ then succ t pos more False
+ else let lose' t' pos' more' = succ t' pos' more' False
+ succ' t' pos' more' = succ t' pos' more' True
+ in prompt t pos more lose' succ'
+{-# INLINE inputSpansChunks #-}
+
+advance :: Int -> Parser ()
+advance n = T.Parser $ \t pos more _lose succ ->
+ succ t (pos + Pos n) more ()
+{-# INLINE advance #-}
+
+ensureSuspended :: Int -> Buffer -> Pos -> More
+ -> Failure r
+ -> Success ByteString r
+ -> Result r
+ensureSuspended n t pos more lose succ =
+ runParser (demandInput >> go) t pos more lose succ
+ where go = T.Parser $ \t' pos' more' lose' succ' ->
+ if lengthAtLeast pos' n t'
+ then succ' t' pos' more' (substring pos (Pos n) t')
+ else runParser (demandInput >> go) t' pos' more' lose' succ'
+
+-- | If at least @n@ elements of input are available, return the
+-- current input, otherwise fail.
+ensure :: Int -> Parser ByteString
+ensure n = T.Parser $ \t pos more lose succ ->
+ if lengthAtLeast pos n t
+ then succ t pos more (substring pos (Pos n) t)
+ -- The uncommon case is kept out-of-line to reduce code size:
+ else ensureSuspended n t pos more lose succ
+-- Non-recursive so the bounds check can be inlined:
+{-# INLINE ensure #-}
+
+-- | Return both the result of a parse and the portion of the input
+-- that was consumed while it was being parsed.
+match :: Parser a -> Parser (ByteString, a)
+match p = T.Parser $ \t pos more lose succ ->
+ let succ' t' pos' more' a =
+ succ t' pos' more' (substring pos (pos'-pos) t', a)
+ in runParser p t pos more lose succ'
+
+lengthAtLeast :: Pos -> Int -> Buffer -> Bool
+lengthAtLeast (Pos pos) n bs = Buf.length bs >= pos + n
+{-# INLINE lengthAtLeast #-}
+
+substring :: Pos -> Pos -> Buffer -> ByteString
+substring (Pos pos) (Pos n) = Buf.substring pos n
+{-# INLINE substring #-}