    {-
    (c) The University of Glasgow 2006
    (c) The University of Glasgow, 1997-2006

    Buffers for scanning string input stored in external arrays.
    -}

    {-# LANGUAGE CPP #-}
    {-# LANGUAGE MagicHash #-}
    {-# LANGUAGE UnboxedTuples #-}

    {-# OPTIONS_GHC -O2 #-}
    -- We always optimise this, otherwise performance of a non-optimised
    -- compiler is severely affected

    module GHC.Data.StringBuffer
           (
            StringBuffer(..),
            -- non-abstract for vs\/HaskellService

             -- * Creation\/destruction
            hGetStringBuffer,
            hGetStringBufferBlock,
            hPutStringBuffer,
            appendStringBuffers,
            stringToStringBuffer,
            stringBufferFromByteString,

            -- * Inspection
            nextChar,
            currentChar,
            prevChar,
            atEnd,
            fingerprintStringBuffer,

            -- * Moving and comparison
            stepOn,
            offsetBytes,
            byteDiff,
            atLine,

            -- * Conversion
            lexemeToString,
            lexemeToFastString,
            decodePrevNChars,

             -- * Parsing integers
            parseUnsignedInteger,

            -- * Checking for bi-directional format characters
            containsBidirectionalFormatChar,
            bidirectionalFormatChars
            ) where

    import GHC.Prelude

    import GHC.Data.FastString
    import GHC.Utils.Encoding
    import GHC.Utils.IO.Unsafe
    import GHC.Utils.Panic.Plain
    import GHC.Utils.Exception      ( bracket_ )
    import GHC.Fingerprint

    import Data.Maybe
    import System.IO
    import System.IO.Unsafe         ( unsafePerformIO )
    import GHC.IO.Encoding.UTF8     ( mkUTF8 )
    import GHC.IO.Encoding.Failure  ( CodingFailureMode(IgnoreCodingFailure) )

    import qualified Data.ByteString.Internal as BS
    import qualified Data.ByteString as BS
    import Data.ByteString ( ByteString )

    import GHC.Exts

    import Foreign
    #if MIN_VERSION_base(4,15,0)
    import GHC.ForeignPtr (unsafeWithForeignPtr)
    #else
    unsafeWithForeignPtr :: ForeignPtr a -> (Ptr a -> IO b) -> IO b
    unsafeWithForeignPtr = withForeignPtr
    #endif

    -- -----------------------------------------------------------------------------
    -- The StringBuffer type

    -- |A StringBuffer is an internal pointer to a sized chunk of bytes.
    -- The bytes are intended to be *immutable*.  There are pure
    -- operations to read the contents of a StringBuffer.
    --
    -- A StringBuffer may have a finalizer, depending on how it was
    -- obtained.
    --
    data StringBuffer
     = StringBuffer {
         StringBuffer -> ForeignPtr Word8
    buf :: {-# UNPACK #-} !(ForeignPtr Word8),
         StringBuffer -> Int
    len :: {-# UNPACK #-} !Int,        -- length
         StringBuffer -> Int
    cur :: {-# UNPACK #-} !Int         -- current pos
      }
      -- The buffer is assumed to be UTF-8 encoded, and furthermore
      -- we add three @\'\\0\'@ bytes to the end as sentinels so that the
      -- decoder doesn't have to check for overflow at every single byte
      -- of a multibyte sequence.

    instance Show StringBuffer where
            showsPrec :: Int -> StringBuffer -> ShowS
    showsPrec Int
    _ StringBuffer
    s = String -> ShowS
    showString String
    "<stringbuffer("
                          ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Int -> ShowS
    forall a. Show a => a -> ShowS
    shows (StringBuffer -> Int
    len StringBuffer
    s) ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . String -> ShowS
    showString String
    "," ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Int -> ShowS
    forall a. Show a => a -> ShowS
    shows (StringBuffer -> Int
    cur StringBuffer
    s)
                          ShowS -> ShowS -> ShowS
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . String -> ShowS
    showString String
    ")>"

    -- -----------------------------------------------------------------------------
    -- Creation / Destruction

    -- | Read a file into a 'StringBuffer'.  The resulting buffer is automatically
    -- managed by the garbage collector.
    hGetStringBuffer :: FilePath -> IO StringBuffer
    hGetStringBuffer :: String -> IO StringBuffer
    hGetStringBuffer String
    fname = do
       h <- String -> IOMode -> IO Handle
    openBinaryFile String
    fname IOMode
    ReadMode
       size_i <- hFileSize h
       offset_i <- skipBOM h size_i 0  -- offset is 0 initially
       let size = Integer -> Int
    forall a b. (Integral a, Num b) => a -> b
    fromIntegral (Integer -> Int) -> Integer -> Int
    forall a b. (a -> b) -> a -> b
    $ Integer
    size_i Integer -> Integer -> Integer
    forall a. Num a => a -> a -> a
    - Integer
    offset_i
       buf <- mallocForeignPtrArray (size+3)
       unsafeWithForeignPtr buf $ \Ptr Word8
    ptr -> do
         r <- if Int
    size Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == Int
    0 then Int -> IO Int
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return Int
    0 else Handle -> Ptr Word8 -> Int -> IO Int
    forall a. Handle -> Ptr a -> Int -> IO Int
    hGetBuf Handle
    h Ptr Word8
    ptr Int
    size
         hClose h
         if (r /= size)
            then ioError (userError "short read of file")
            else newUTF8StringBuffer buf ptr size

    hGetStringBufferBlock :: Handle -> Int -> IO StringBuffer
    hGetStringBufferBlock :: Handle -> Int -> IO StringBuffer
    hGetStringBufferBlock Handle
    handle Int
    wanted
        = do size_i <- Handle -> IO Integer
    hFileSize Handle
    handle
             offset_i <- hTell handle >>= skipBOM handle size_i
             let size = Int -> Int -> Int
    forall a. Ord a => a -> a -> a
    min Int
    wanted (Integer -> Int
    forall a b. (Integral a, Num b) => a -> b
    fromIntegral (Integer -> Int) -> Integer -> Int
    forall a b. (a -> b) -> a -> b
    $ Integer
    size_iInteger -> Integer -> Integer
    forall a. Num a => a -> a -> a
    -Integer
    offset_i)
             buf <- mallocForeignPtrArray (size+3)
             unsafeWithForeignPtr buf $ \Ptr Word8
    ptr ->
                 do r <- if Int
    size Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == Int
    0 then Int -> IO Int
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return Int
    0 else Handle -> Ptr Word8 -> Int -> IO Int
    forall a. Handle -> Ptr a -> Int -> IO Int
    hGetBuf Handle
    handle Ptr Word8
    ptr Int
    size
                    if r /= size
                       then ioError (userError $ "short read of file: "++show(r,size,size_i,handle))
                       else newUTF8StringBuffer buf ptr size

    hPutStringBuffer :: Handle -> StringBuffer -> IO ()
    hPutStringBuffer :: Handle -> StringBuffer -> IO ()
    hPutStringBuffer Handle
    hdl (StringBuffer ForeignPtr Word8
    buf Int
    len Int
    cur)
        = ForeignPtr (ZonkAny 0) -> (Ptr (ZonkAny 0) -> IO ()) -> IO ()
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    unsafeWithForeignPtr (ForeignPtr Word8 -> Int -> ForeignPtr (ZonkAny 0)
    forall a b. ForeignPtr a -> Int -> ForeignPtr b
    plusForeignPtr ForeignPtr Word8
    buf Int
    cur) ((Ptr (ZonkAny 0) -> IO ()) -> IO ())
    -> (Ptr (ZonkAny 0) -> IO ()) -> IO ()
    forall a b. (a -> b) -> a -> b
    $ \Ptr (ZonkAny 0)
    ptr ->
              Handle -> Ptr (ZonkAny 0) -> Int -> IO ()
    forall a. Handle -> Ptr a -> Int -> IO ()
    hPutBuf Handle
    hdl Ptr (ZonkAny 0)
    ptr Int
    len

    -- | Skip the byte-order mark if there is one (see #1744 and #6016),
    -- and return the new position of the handle in bytes.
    --
    -- This is better than treating #FEFF as whitespace,
    -- because that would mess up layout.  We don't have a concept
    -- of zero-width whitespace in Haskell: all whitespace codepoints
    -- have a width of one column.
    skipBOM :: Handle -> Integer -> Integer -> IO Integer
    skipBOM :: Handle -> Integer -> Integer -> IO Integer
    skipBOM Handle
    h Integer
    size Integer
    offset =
      -- Only skip BOM at the beginning of a file.
      if Integer
    size Integer -> Integer -> Bool
    forall a. Ord a => a -> a -> Bool
    > Integer
    0 Bool -> Bool -> Bool
    && Integer
    offset Integer -> Integer -> Bool
    forall a. Eq a => a -> a -> Bool
    == Integer
    0
        then do
          -- Validate assumption that handle is in binary mode.
          IO Bool -> IO ()
    forall (m :: * -> *). (HasCallStack, Monad m) => m Bool -> m ()
    assertM (Handle -> IO (Maybe TextEncoding)
    hGetEncoding Handle
    h IO (Maybe TextEncoding)
    -> (Maybe TextEncoding -> IO Bool) -> IO Bool
    forall a b. IO a -> (a -> IO b) -> IO b
    forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
    >>= Bool -> IO Bool
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Bool -> IO Bool)
    -> (Maybe TextEncoding -> Bool) -> Maybe TextEncoding -> IO Bool
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . Maybe TextEncoding -> Bool
    forall a. Maybe a -> Bool
    isNothing)
          -- Temporarily select utf8 encoding with error ignoring,
          -- to make `hLookAhead` and `hGetChar` return full Unicode characters.
          IO () -> IO () -> IO Integer -> IO Integer
    forall a b c. IO a -> IO b -> IO c -> IO c
    bracket_ (Handle -> TextEncoding -> IO ()
    hSetEncoding Handle
    h TextEncoding
    safeEncoding) (Handle -> Bool -> IO ()
    hSetBinaryMode Handle
    h Bool
    True) (IO Integer -> IO Integer) -> IO Integer -> IO Integer
    forall a b. (a -> b) -> a -> b
    $ do
            c <- Handle -> IO Char
    hLookAhead Handle
    h
            if c == '\xfeff'
              then hGetChar h >> hTell h
              else return offset
        else Integer -> IO Integer
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return Integer
    offset
      where
        safeEncoding :: TextEncoding
    safeEncoding = CodingFailureMode -> TextEncoding
    mkUTF8 CodingFailureMode
    IgnoreCodingFailure

    newUTF8StringBuffer :: ForeignPtr Word8 -> Ptr Word8 -> Int -> IO StringBuffer
    newUTF8StringBuffer :: ForeignPtr Word8 -> Ptr Word8 -> Int -> IO StringBuffer
    newUTF8StringBuffer ForeignPtr Word8
    buf Ptr Word8
    ptr Int
    size = do
      Ptr Word8 -> [Word8] -> IO ()
    forall a. Storable a => Ptr a -> [a] -> IO ()
    pokeArray (Ptr Word8
    ptr Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    `plusPtr` Int
    size :: Ptr Word8) [Word8
    0,Word8
    0,Word8
    0]
      -- sentinels for UTF-8 decoding
      StringBuffer -> IO StringBuffer
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return (StringBuffer -> IO StringBuffer)
    -> StringBuffer -> IO StringBuffer
    forall a b. (a -> b) -> a -> b
    $ ForeignPtr Word8 -> Int -> Int -> StringBuffer
    StringBuffer ForeignPtr Word8
    buf Int
    size Int
    0

    appendStringBuffers :: StringBuffer -> StringBuffer -> IO StringBuffer
    appendStringBuffers :: StringBuffer -> StringBuffer -> IO StringBuffer
    appendStringBuffers StringBuffer
    sb1 StringBuffer
    sb2
        = do newBuf <- Int -> IO (ForeignPtr Word8)
    forall a. Storable a => Int -> IO (ForeignPtr a)
    mallocForeignPtrArray (Int
    sizeInt -> Int -> Int
    forall a. Num a => a -> a -> a
    +Int
    3)
             unsafeWithForeignPtr newBuf $ \Ptr Word8
    ptr ->
              ForeignPtr Word8
    -> (Ptr Word8 -> IO StringBuffer) -> IO StringBuffer
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    unsafeWithForeignPtr (StringBuffer -> ForeignPtr Word8
    buf StringBuffer
    sb1) ((Ptr Word8 -> IO StringBuffer) -> IO StringBuffer)
    -> (Ptr Word8 -> IO StringBuffer) -> IO StringBuffer
    forall a b. (a -> b) -> a -> b
    $ \Ptr Word8
    sb1Ptr ->
               ForeignPtr Word8
    -> (Ptr Word8 -> IO StringBuffer) -> IO StringBuffer
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    unsafeWithForeignPtr (StringBuffer -> ForeignPtr Word8
    buf StringBuffer
    sb2) ((Ptr Word8 -> IO StringBuffer) -> IO StringBuffer)
    -> (Ptr Word8 -> IO StringBuffer) -> IO StringBuffer
    forall a b. (a -> b) -> a -> b
    $ \Ptr Word8
    sb2Ptr ->
                 do Ptr Word8 -> Ptr Word8 -> Int -> IO ()
    forall a. Storable a => Ptr a -> Ptr a -> Int -> IO ()
    copyArray Ptr Word8
    ptr (Ptr Word8
    sb1Ptr Ptr Word8 -> Int -> Ptr Word8
    forall a. Storable a => Ptr a -> Int -> Ptr a
    `advancePtr` StringBuffer -> Int
    cur StringBuffer
    sb1) Int
    sb1_len
                    Ptr Word8 -> Ptr Word8 -> Int -> IO ()
    forall a. Storable a => Ptr a -> Ptr a -> Int -> IO ()
    copyArray (Ptr Word8
    ptr Ptr Word8 -> Int -> Ptr Word8
    forall a. Storable a => Ptr a -> Int -> Ptr a
    `advancePtr` Int
    sb1_len) (Ptr Word8
    sb2Ptr Ptr Word8 -> Int -> Ptr Word8
    forall a. Storable a => Ptr a -> Int -> Ptr a
    `advancePtr` StringBuffer -> Int
    cur StringBuffer
    sb2) Int
    sb2_len
                    Ptr Word8 -> [Word8] -> IO ()
    forall a. Storable a => Ptr a -> [a] -> IO ()
    pokeArray (Ptr Word8
    ptr Ptr Word8 -> Int -> Ptr Word8
    forall a. Storable a => Ptr a -> Int -> Ptr a
    `advancePtr` Int
    size) [Word8
    0,Word8
    0,Word8
    0]
                    StringBuffer -> IO StringBuffer
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return (ForeignPtr Word8 -> Int -> Int -> StringBuffer
    StringBuffer ForeignPtr Word8
    newBuf Int
    size Int
    0)
        where sb1_len :: Int
    sb1_len = StringBuffer -> Int
    calcLen StringBuffer
    sb1
              sb2_len :: Int
    sb2_len = StringBuffer -> Int
    calcLen StringBuffer
    sb2
              calcLen :: StringBuffer -> Int
    calcLen StringBuffer
    sb = StringBuffer -> Int
    len StringBuffer
    sb Int -> Int -> Int
    forall a. Num a => a -> a -> a
    - StringBuffer -> Int
    cur StringBuffer
    sb
              size :: Int
    size =  Int
    sb1_len Int -> Int -> Int
    forall a. Num a => a -> a -> a
    + Int
    sb2_len

    -- | Encode a 'String' into a 'StringBuffer' as UTF-8.  The resulting buffer
    -- is automatically managed by the garbage collector.
    stringToStringBuffer :: String -> StringBuffer
    stringToStringBuffer :: String -> StringBuffer
    stringToStringBuffer String
    str =
     IO StringBuffer -> StringBuffer
    forall a. IO a -> a
    unsafePerformIO (IO StringBuffer -> StringBuffer)
    -> IO StringBuffer -> StringBuffer
    forall a b. (a -> b) -> a -> b
    $ do
      let size :: Int
    size = String -> Int
    utf8EncodedLength String
    str
      buf <- Int -> IO (ForeignPtr Word8)
    forall a. Storable a => Int -> IO (ForeignPtr a)
    mallocForeignPtrArray (Int
    sizeInt -> Int -> Int
    forall a. Num a => a -> a -> a
    +Int
    3)
      unsafeWithForeignPtr buf $ \Ptr Word8
    ptr -> do
        Ptr Word8 -> String -> IO ()
    utf8EncodePtr Ptr Word8
    ptr String
    str
        Ptr Word8 -> [Word8] -> IO ()
    forall a. Storable a => Ptr a -> [a] -> IO ()
    pokeArray (Ptr Word8
    ptr Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    `plusPtr` Int
    size :: Ptr Word8) [Word8
    0,Word8
    0,Word8
    0]
        -- sentinels for UTF-8 decoding
      return (StringBuffer buf size 0)

    -- | Convert a UTF-8 encoded 'ByteString' into a 'StringBuffer. This really
    -- relies on the internals of both 'ByteString' and 'StringBuffer'.
    --
    -- /O(n)/ (but optimized into a @memcpy@ by @bytestring@ under the hood)
    stringBufferFromByteString :: ByteString -> StringBuffer
    stringBufferFromByteString :: ByteString -> StringBuffer
    stringBufferFromByteString ByteString
    bs =
      let BS.PS ForeignPtr Word8
    fp Int
    off Int
    len = ByteString -> ByteString -> ByteString
    BS.append ByteString
    bs ([Word8] -> ByteString
    BS.pack [Word8
    0,Word8
    0,Word8
    0])
      in StringBuffer { buf :: ForeignPtr Word8
    buf = ForeignPtr Word8
    fp, len :: Int
    len = Int
    len Int -> Int -> Int
    forall a. Num a => a -> a -> a
    - Int
    3, cur :: Int
    cur = Int
    off }

    -- -----------------------------------------------------------------------------
    -- Grab a character

    -- | Return the first UTF-8 character of a nonempty 'StringBuffer' and as well
    -- the remaining portion (analogous to 'Data.List.uncons').  __Warning:__ The
    -- behavior is undefined if the 'StringBuffer' is empty.  The result shares
    -- the same buffer as the original.  Similar to 'utf8DecodeChar', if the
    -- character cannot be decoded as UTF-8, @\'\\0\'@ is returned.
    {-# INLINE nextChar #-}
    nextChar :: StringBuffer -> (Char,StringBuffer)
    nextChar :: StringBuffer -> (Char, StringBuffer)
    nextChar (StringBuffer ForeignPtr Word8
    buf Int
    len (I# Int#
    cur#)) =
      -- Getting our fingers dirty a little here, but this is performance-critical
      IO (Char, StringBuffer) -> (Char, StringBuffer)
    forall a. IO a -> a
    inlinePerformIO (IO (Char, StringBuffer) -> (Char, StringBuffer))
    -> IO (Char, StringBuffer) -> (Char, StringBuffer)
    forall a b. (a -> b) -> a -> b
    $
        ForeignPtr Word8
    -> (Ptr Word8 -> IO (Char, StringBuffer))
    -> IO (Char, StringBuffer)
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    unsafeWithForeignPtr ForeignPtr Word8
    buf ((Ptr Word8 -> IO (Char, StringBuffer)) -> IO (Char, StringBuffer))
    -> (Ptr Word8 -> IO (Char, StringBuffer))
    -> IO (Char, StringBuffer)
    forall a b. (a -> b) -> a -> b
    $ \(Ptr Addr#
    a#) ->
            case Addr# -> Int# -> (# Char#, Int# #)
    utf8DecodeCharAddr# (Addr#
    a# Addr# -> Int# -> Addr#
    `plusAddr#` Int#
    cur#) Int#
    0# of
              (# Char#
    c#, Int#
    nBytes# #) ->
                 let cur' :: Int
    cur' = Int# -> Int
    I# (Int#
    cur# Int# -> Int# -> Int#
    +# Int#
    nBytes#) in
                 (Char, StringBuffer) -> IO (Char, StringBuffer)
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Char# -> Char
    C# Char#
    c#, ForeignPtr Word8 -> Int -> Int -> StringBuffer
    StringBuffer ForeignPtr Word8
    buf Int
    len Int
    cur')

    bidirectionalFormatChars :: [(Char,String)]
    bidirectionalFormatChars :: [(Char, String)]
    bidirectionalFormatChars =
      [ (Char
    '\x202a' , String
    "U+202A LEFT-TO-RIGHT EMBEDDING (LRE)")
      , (Char
    '\x202b' , String
    "U+202B RIGHT-TO-LEFT EMBEDDING (RLE)")
      , (Char
    '\x202c' , String
    "U+202C POP DIRECTIONAL FORMATTING (PDF)")
      , (Char
    '\x202d' , String
    "U+202D LEFT-TO-RIGHT OVERRIDE (LRO)")
      , (Char
    '\x202e' , String
    "U+202E RIGHT-TO-LEFT OVERRIDE (RLO)")
      , (Char
    '\x2066' , String
    "U+2066 LEFT-TO-RIGHT ISOLATE (LRI)")
      , (Char
    '\x2067' , String
    "U+2067 RIGHT-TO-LEFT ISOLATE (RLI)")
      , (Char
    '\x2068' , String
    "U+2068 FIRST STRONG ISOLATE (FSI)")
      , (Char
    '\x2069' , String
    "U+2069 POP DIRECTIONAL ISOLATE (PDI)")
      ]

    {-| Returns true if the buffer contains Unicode bi-directional formatting
    characters.

    https://www.unicode.org/reports/tr9/#Bidirectional_Character_Types

    Bidirectional format characters are one of
    '\x202a' : "U+202A LEFT-TO-RIGHT EMBEDDING (LRE)"
    '\x202b' : "U+202B RIGHT-TO-LEFT EMBEDDING (RLE)"
    '\x202c' : "U+202C POP DIRECTIONAL FORMATTING (PDF)"
    '\x202d' : "U+202D LEFT-TO-RIGHT OVERRIDE (LRO)"
    '\x202e' : "U+202E RIGHT-TO-LEFT OVERRIDE (RLO)"
    '\x2066' : "U+2066 LEFT-TO-RIGHT ISOLATE (LRI)"
    '\x2067' : "U+2067 RIGHT-TO-LEFT ISOLATE (RLI)"
    '\x2068' : "U+2068 FIRST STRONG ISOLATE (FSI)"
    '\x2069' : "U+2069 POP DIRECTIONAL ISOLATE (PDI)"

    This list is encoded in 'bidirectionalFormatChars'

    -}
    {-# INLINE containsBidirectionalFormatChar #-}
    containsBidirectionalFormatChar :: StringBuffer -> Bool
    containsBidirectionalFormatChar :: StringBuffer -> Bool
    containsBidirectionalFormatChar (StringBuffer ForeignPtr Word8
    buf (I# Int#
    len#) (I# Int#
    cur#))
      = IO Bool -> Bool
    forall a. IO a -> a
    inlinePerformIO (IO Bool -> Bool) -> IO Bool -> Bool
    forall a b. (a -> b) -> a -> b
    $ ForeignPtr Word8 -> (Ptr Word8 -> IO Bool) -> IO Bool
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    unsafeWithForeignPtr ForeignPtr Word8
    buf ((Ptr Word8 -> IO Bool) -> IO Bool)
    -> (Ptr Word8 -> IO Bool) -> IO Bool
    forall a b. (a -> b) -> a -> b
    $ \(Ptr Addr#
    a#) -> do
      let go :: Int# -> Bool
          go :: Int# -> Bool
    go Int#
    i | Int# -> Bool
    isTrue# (Int#
    i Int# -> Int# -> Int#
    >=# Int#
    len#) = Bool
    False
               | Bool
    otherwise = case Addr# -> Int# -> (# Char#, Int# #)
    utf8DecodeCharAddr# Addr#
    a# Int#
    i of
                    (# Char#
    '\x202a'#  , Int#
    _ #) -> Bool
    True
                    (# Char#
    '\x202b'#  , Int#
    _ #) -> Bool
    True
                    (# Char#
    '\x202c'#  , Int#
    _ #) -> Bool
    True
                    (# Char#
    '\x202d'#  , Int#
    _ #) -> Bool
    True
                    (# Char#
    '\x202e'#  , Int#
    _ #) -> Bool
    True
                    (# Char#
    '\x2066'#  , Int#
    _ #) -> Bool
    True
                    (# Char#
    '\x2067'#  , Int#
    _ #) -> Bool
    True
                    (# Char#
    '\x2068'#  , Int#
    _ #) -> Bool
    True
                    (# Char#
    '\x2069'#  , Int#
    _ #) -> Bool
    True
                    (# Char#
    _, Int#
    bytes #) -> Int# -> Bool
    go (Int#
    i Int# -> Int# -> Int#
    +# Int#
    bytes)
      Bool -> IO Bool
    forall a. a -> IO a
    forall (f :: * -> *) a. Applicative f => a -> f a
    pure (Bool -> IO Bool) -> Bool -> IO Bool
    forall a b. (a -> b) -> a -> b
    $! Int# -> Bool
    go Int#
    cur#

    -- | Return the first UTF-8 character of a nonempty 'StringBuffer' (analogous
    -- to 'Data.List.head').  __Warning:__ The behavior is undefined if the
    -- 'StringBuffer' is empty.  Similar to 'utf8DecodeChar', if the character
    -- cannot be decoded as UTF-8, @\'\\0\'@ is returned.
    currentChar :: StringBuffer -> Char
    currentChar :: StringBuffer -> Char
    currentChar = (Char, StringBuffer) -> Char
    forall a b. (a, b) -> a
    fst ((Char, StringBuffer) -> Char)
    -> (StringBuffer -> (Char, StringBuffer)) -> StringBuffer -> Char
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . StringBuffer -> (Char, StringBuffer)
    nextChar

    prevChar :: StringBuffer -> Char -> Char
    prevChar :: StringBuffer -> Char -> Char
    prevChar (StringBuffer ForeignPtr Word8
    _   Int
    _   Int
    0)   Char
    deflt = Char
    deflt
    prevChar (StringBuffer ForeignPtr Word8
    buf Int
    _   Int
    cur) Char
    _     =
      IO Char -> Char
    forall a. IO a -> a
    inlinePerformIO (IO Char -> Char) -> IO Char -> Char
    forall a b. (a -> b) -> a -> b
    $
        ForeignPtr Word8 -> (Ptr Word8 -> IO Char) -> IO Char
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    unsafeWithForeignPtr ForeignPtr Word8
    buf ((Ptr Word8 -> IO Char) -> IO Char)
    -> (Ptr Word8 -> IO Char) -> IO Char
    forall a b. (a -> b) -> a -> b
    $ \Ptr Word8
    p -> do
          p' <- Ptr Word8 -> IO (Ptr Word8)
    utf8PrevChar (Ptr Word8
    p Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    `plusPtr` Int
    cur)
          return (fst (utf8DecodeCharPtr p'))

    -- -----------------------------------------------------------------------------
    -- Moving

    -- | Return a 'StringBuffer' with the first UTF-8 character removed (analogous
    -- to 'Data.List.tail').  __Warning:__ The behavior is undefined if the
    -- 'StringBuffer' is empty.  The result shares the same buffer as the
    -- original.
    stepOn :: StringBuffer -> StringBuffer
    stepOn :: StringBuffer -> StringBuffer
    stepOn StringBuffer
    s = (Char, StringBuffer) -> StringBuffer
    forall a b. (a, b) -> b
    snd (StringBuffer -> (Char, StringBuffer)
    nextChar StringBuffer
    s)

    -- | Return a 'StringBuffer' with the first @n@ bytes removed.  __Warning:__
    -- If there aren't enough characters, the returned 'StringBuffer' will be
    -- invalid and any use of it may lead to undefined behavior.  The result
    -- shares the same buffer as the original.
    offsetBytes :: Int                      -- ^ @n@, the number of bytes
                -> StringBuffer
                -> StringBuffer
    offsetBytes :: Int -> StringBuffer -> StringBuffer
    offsetBytes Int
    i StringBuffer
    s = StringBuffer
    s { cur = cur s + i }

    -- | Compute the difference in offset between two 'StringBuffer's that share
    -- the same buffer.  __Warning:__ The behavior is undefined if the
    -- 'StringBuffer's use separate buffers.
    byteDiff :: StringBuffer -> StringBuffer -> Int
    byteDiff :: StringBuffer -> StringBuffer -> Int
    byteDiff StringBuffer
    s1 StringBuffer
    s2 = StringBuffer -> Int
    cur StringBuffer
    s2 Int -> Int -> Int
    forall a. Num a => a -> a -> a
    - StringBuffer -> Int
    cur StringBuffer
    s1

    -- | Check whether a 'StringBuffer' is empty (analogous to 'Data.List.null').
    atEnd :: StringBuffer -> Bool
    atEnd :: StringBuffer -> Bool
    atEnd (StringBuffer ForeignPtr Word8
    _ Int
    l Int
    c) = Int
    l Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == Int
    c

    -- | Computes a hash of the contents of a 'StringBuffer'.
    fingerprintStringBuffer :: StringBuffer -> Fingerprint
    fingerprintStringBuffer :: StringBuffer -> Fingerprint
    fingerprintStringBuffer (StringBuffer ForeignPtr Word8
    buf Int
    len Int
    cur) =
      IO Fingerprint -> Fingerprint
    forall a. IO a -> a
    unsafePerformIO (IO Fingerprint -> Fingerprint) -> IO Fingerprint -> Fingerprint
    forall a b. (a -> b) -> a -> b
    $
        ForeignPtr Word8 -> (Ptr Word8 -> IO Fingerprint) -> IO Fingerprint
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    withForeignPtr ForeignPtr Word8
    buf ((Ptr Word8 -> IO Fingerprint) -> IO Fingerprint)
    -> (Ptr Word8 -> IO Fingerprint) -> IO Fingerprint
    forall a b. (a -> b) -> a -> b
    $ \Ptr Word8
    ptr ->
          Ptr Word8 -> Int -> IO Fingerprint
    fingerprintData (Ptr Word8
    ptr Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    `plusPtr` Int
    cur) Int
    len

    -- | Computes a 'StringBuffer' which points to the first character of the
    -- wanted line. Lines begin at 1.
    atLine :: Int -> StringBuffer -> Maybe StringBuffer
    atLine :: Int -> StringBuffer -> Maybe StringBuffer
    atLine Int
    line sb :: StringBuffer
    sb@(StringBuffer ForeignPtr Word8
    buf Int
    len Int
    _) =
      IO (Maybe StringBuffer) -> Maybe StringBuffer
    forall a. IO a -> a
    inlinePerformIO (IO (Maybe StringBuffer) -> Maybe StringBuffer)
    -> IO (Maybe StringBuffer) -> Maybe StringBuffer
    forall a b. (a -> b) -> a -> b
    $
        ForeignPtr Word8
    -> (Ptr Word8 -> IO (Maybe StringBuffer))
    -> IO (Maybe StringBuffer)
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    unsafeWithForeignPtr ForeignPtr Word8
    buf ((Ptr Word8 -> IO (Maybe StringBuffer)) -> IO (Maybe StringBuffer))
    -> (Ptr Word8 -> IO (Maybe StringBuffer))
    -> IO (Maybe StringBuffer)
    forall a b. (a -> b) -> a -> b
    $ \Ptr Word8
    p -> do
          p' <- Int -> Int -> Ptr Word8 -> IO (Ptr Word8)
    skipToLine Int
    line Int
    len Ptr Word8
    p
          if p' == nullPtr
            then return Nothing
            else
              let
                delta = Ptr Word8
    p' Ptr Word8 -> Ptr Word8 -> Int
    forall a b. Ptr a -> Ptr b -> Int
    `minusPtr` Ptr Word8
    p
              in return $ Just (sb { cur = delta
                                   , len = len - delta
                                   })

    skipToLine :: Int -> Int -> Ptr Word8 -> IO (Ptr Word8)
    skipToLine :: Int -> Int -> Ptr Word8 -> IO (Ptr Word8)
    skipToLine !Int
    line !Int
    len !Ptr Word8
    op0 = Int -> Ptr Word8 -> IO (Ptr Word8)
    go Int
    1 Ptr Word8
    op0
      where
        !opend :: Ptr Word8
    opend = Ptr Word8
    op0 Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    `plusPtr` Int
    len

        go :: Int -> Ptr Word8 -> IO (Ptr Word8)
    go !Int
    i_line !Ptr Word8
    op
          | Ptr Word8
    op Ptr Word8 -> Ptr Word8 -> Bool
    forall a. Ord a => a -> a -> Bool
    >= Ptr Word8
    opend    = Ptr Word8 -> IO (Ptr Word8)
    forall a. a -> IO a
    forall (f :: * -> *) a. Applicative f => a -> f a
    pure Ptr Word8
    forall a. Ptr a
    nullPtr
          | Int
    i_line Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == Int
    line = Ptr Word8 -> IO (Ptr Word8)
    forall a. a -> IO a
    forall (f :: * -> *) a. Applicative f => a -> f a
    pure Ptr Word8
    op
          | Bool
    otherwise      = do
              w <- Ptr Word8 -> IO Word8
    forall a. Storable a => Ptr a -> IO a
    peek Ptr Word8
    op :: IO Word8
              case w of
                Word8
    10 -> Int -> Ptr Word8 -> IO (Ptr Word8)
    go (Int
    i_line Int -> Int -> Int
    forall a. Num a => a -> a -> a
    + Int
    1) (Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    plusPtr Ptr Word8
    op Int
    1)
                Word8
    13 -> do
                  -- this is safe because a 'StringBuffer' is
                  -- guaranteed to have 3 bytes sentinel values.
                  w' <- Ptr Word8 -> IO Word8
    forall a. Storable a => Ptr a -> IO a
    peek (Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    plusPtr Ptr Word8
    op Int
    1) :: IO Word8
                  case w' of
                    Word8
    10 -> Int -> Ptr Word8 -> IO (Ptr Word8)
    go (Int
    i_line Int -> Int -> Int
    forall a. Num a => a -> a -> a
    + Int
    1) (Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    plusPtr Ptr Word8
    op Int
    2)
                    Word8
    _  -> Int -> Ptr Word8 -> IO (Ptr Word8)
    go (Int
    i_line Int -> Int -> Int
    forall a. Num a => a -> a -> a
    + Int
    1) (Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    plusPtr Ptr Word8
    op Int
    1)
                Word8
    _  -> Int -> Ptr Word8 -> IO (Ptr Word8)
    go Int
    i_line (Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    plusPtr Ptr Word8
    op Int
    1)

    -- -----------------------------------------------------------------------------
    -- Conversion

    -- | Decode the first @n@ bytes of a 'StringBuffer' as UTF-8 into a 'String'.
    -- Similar to 'utf8DecodeChar', if the character cannot be decoded as UTF-8,
    -- they will be replaced with @\'\\0\'@.
    lexemeToString :: StringBuffer
                   -> Int                   -- ^ @n@, the number of bytes
                   -> String
    lexemeToString :: StringBuffer -> Int -> String
    lexemeToString StringBuffer
    _ Int
    0 = String
    ""
    lexemeToString (StringBuffer ForeignPtr Word8
    buf Int
    _ Int
    cur) Int
    bytes =
      ForeignPtr Word8 -> Int -> Int -> String
    utf8DecodeForeignPtr ForeignPtr Word8
    buf Int
    cur Int
    bytes

    lexemeToFastString :: StringBuffer
                       -> Int               -- ^ @n@, the number of bytes
                       -> FastString
    lexemeToFastString :: StringBuffer -> Int -> FastString
    lexemeToFastString StringBuffer
    _ Int
    0 = FastString
    nilFS
    lexemeToFastString (StringBuffer ForeignPtr Word8
    buf Int
    _ Int
    cur) Int
    len =
       IO FastString -> FastString
    forall a. IO a -> a
    inlinePerformIO (IO FastString -> FastString) -> IO FastString -> FastString
    forall a b. (a -> b) -> a -> b
    $
         ForeignPtr Word8 -> (Ptr Word8 -> IO FastString) -> IO FastString
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    unsafeWithForeignPtr ForeignPtr Word8
    buf ((Ptr Word8 -> IO FastString) -> IO FastString)
    -> (Ptr Word8 -> IO FastString) -> IO FastString
    forall a b. (a -> b) -> a -> b
    $ \Ptr Word8
    ptr ->
           FastString -> IO FastString
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return (FastString -> IO FastString) -> FastString -> IO FastString
    forall a b. (a -> b) -> a -> b
    $! Ptr Word8 -> Int -> FastString
    mkFastStringBytes (Ptr Word8
    ptr Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    `plusPtr` Int
    cur) Int
    len

    -- | Return the previous @n@ characters (or fewer if we are less than @n@
    -- characters into the buffer.
    decodePrevNChars :: Int -> StringBuffer -> String
    decodePrevNChars :: Int -> StringBuffer -> String
    decodePrevNChars Int
    n (StringBuffer ForeignPtr Word8
    buf Int
    _ Int
    cur) =
        IO String -> String
    forall a. IO a -> a
    inlinePerformIO (IO String -> String) -> IO String -> String
    forall a b. (a -> b) -> a -> b
    $ ForeignPtr Word8 -> (Ptr Word8 -> IO String) -> IO String
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    unsafeWithForeignPtr ForeignPtr Word8
    buf ((Ptr Word8 -> IO String) -> IO String)
    -> (Ptr Word8 -> IO String) -> IO String
    forall a b. (a -> b) -> a -> b
    $ \Ptr Word8
    p0 ->
          Ptr Word8 -> Int -> String -> Ptr Word8 -> IO String
    go Ptr Word8
    p0 Int
    n String
    "" (Ptr Word8
    p0 Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    `plusPtr` (Int
    cur Int -> Int -> Int
    forall a. Num a => a -> a -> a
    - Int
    1))
      where
        go :: Ptr Word8 -> Int -> String -> Ptr Word8 -> IO String
        go :: Ptr Word8 -> Int -> String -> Ptr Word8 -> IO String
    go Ptr Word8
    buf0 Int
    n String
    acc Ptr Word8
    p | Int
    n Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == Int
    0 Bool -> Bool -> Bool
    || Ptr Word8
    buf0 Ptr Word8 -> Ptr Word8 -> Bool
    forall a. Ord a => a -> a -> Bool
    >= Ptr Word8
    p = String -> IO String
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return String
    acc
        go Ptr Word8
    buf0 Int
    n String
    acc Ptr Word8
    p = do
            p' <- Ptr Word8 -> IO (Ptr Word8)
    utf8PrevChar Ptr Word8
    p
            let (c,_) = utf8DecodeCharPtr p'
            go buf0 (n - 1) (c:acc) p'

    -- -----------------------------------------------------------------------------
    -- Parsing integer strings in various bases
    parseUnsignedInteger :: StringBuffer -> Int -> Integer -> (Char->Int) -> Integer
    parseUnsignedInteger :: StringBuffer -> Int -> Integer -> (Char -> Int) -> Integer
    parseUnsignedInteger (StringBuffer ForeignPtr Word8
    buf Int
    _ Int
    cur) Int
    len Integer
    radix Char -> Int
    char_to_int
      = IO Integer -> Integer
    forall a. IO a -> a
    inlinePerformIO (IO Integer -> Integer) -> IO Integer -> Integer
    forall a b. (a -> b) -> a -> b
    $ ForeignPtr Word8 -> (Ptr Word8 -> IO Integer) -> IO Integer
    forall a b. ForeignPtr a -> (Ptr a -> IO b) -> IO b
    withForeignPtr ForeignPtr Word8
    buf ((Ptr Word8 -> IO Integer) -> IO Integer)
    -> (Ptr Word8 -> IO Integer) -> IO Integer
    forall a b. (a -> b) -> a -> b
    $ \Ptr Word8
    ptr -> Integer -> IO Integer
    forall a. a -> IO a
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Integer -> IO Integer) -> Integer -> IO Integer
    forall a b. (a -> b) -> a -> b
    $! let
        go :: Int -> Integer -> Integer
    go Int
    i Integer
    x | Int
    i Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == Int
    len  = Integer
    x
               | Bool
    otherwise = case (Char, Int) -> Char
    forall a b. (a, b) -> a
    fst (Ptr Word8 -> (Char, Int)
    utf8DecodeCharPtr (Ptr Word8
    ptr Ptr Word8 -> Int -> Ptr Word8
    forall a b. Ptr a -> Int -> Ptr b
    `plusPtr` (Int
    cur Int -> Int -> Int
    forall a. Num a => a -> a -> a
    + Int
    i))) of
                   Char
    '_'  -> Int -> Integer -> Integer
    go (Int
    i Int -> Int -> Int
    forall a. Num a => a -> a -> a
    + Int
    1) Integer
    x    -- skip "_" (#14473)
                   Char
    char -> Int -> Integer -> Integer
    go (Int
    i Int -> Int -> Int
    forall a. Num a => a -> a -> a
    + Int
    1) (Integer
    x Integer -> Integer -> Integer
    forall a. Num a => a -> a -> a
    * Integer
    radix Integer -> Integer -> Integer
    forall a. Num a => a -> a -> a
    + Int -> Integer
    forall a. Integral a => a -> Integer
    toInteger (Char -> Int
    char_to_int Char
    char))
      in Int -> Integer -> Integer
    go Int
    0 Integer
    0