{-# LANGUAGE BangPatterns #-} {-# LANGUAGE MagicHash #-} {-# LANGUAGE NamedFieldPuns #-} {-# LANGUAGE TupleSections #-} {-# OPTIONS_HADDOCK prune #-} {-# LANGUAGE Trustworthy #-} -- | -- Module : Data.ByteString -- Copyright : (c) The University of Glasgow 2001, -- (c) David Roundy 2003-2005, -- (c) Simon Marlow 2005, -- (c) Bjorn Bringert 2006, -- (c) Don Stewart 2005-2008, -- (c) Duncan Coutts 2006-2013 -- License : BSD-style -- -- Maintainer : dons00@gmail.com, duncan@community.haskell.org -- Stability : stable -- Portability : portable -- -- A time- and space-efficient implementation of byte vectors using -- packed Word8 arrays, suitable for high performance use, both in terms -- of large data quantities and high speed requirements. Byte vectors -- are encoded as strict 'Word8' arrays of bytes, held in a 'ForeignPtr', -- and can be passed between C and Haskell with little effort. -- -- The recomended way to assemble ByteStrings from smaller parts -- is to use the builder monoid from "Data.ByteString.Builder". -- -- This module is intended to be imported @qualified@, to avoid name -- clashes with "Prelude" functions. eg. -- -- > import qualified Data.ByteString as B -- -- Original GHC implementation by Bryan O\'Sullivan. -- Rewritten to use 'Data.Array.Unboxed.UArray' by Simon Marlow. -- Rewritten to support slices and use 'ForeignPtr' by David Roundy. -- Rewritten again and extended by Don Stewart and Duncan Coutts. -- module Data.ByteString ( -- * Strict @ByteString@ ByteString, StrictByteString, -- * Introducing and eliminating 'ByteString's empty, singleton, pack, unpack, fromStrict, toStrict, fromFilePath, toFilePath, -- * Basic interface cons, snoc, append, head, uncons, unsnoc, last, tail, init, null, length, -- * Transforming ByteStrings map, reverse, intersperse, intercalate, transpose, -- * Reducing 'ByteString's (folds) foldl, foldl', foldl1, foldl1', foldr, foldr', foldr1, foldr1', -- ** Special folds concat, concatMap, any, all, maximum, minimum, -- * Building ByteStrings -- ** Scans scanl, scanl1, scanr, scanr1, -- ** Accumulating maps mapAccumL, mapAccumR, -- ** Generating and unfolding ByteStrings replicate, unfoldr, unfoldrN, -- * Substrings -- ** Breaking strings take, takeEnd, drop, dropEnd, splitAt, takeWhile, takeWhileEnd, dropWhile, dropWhileEnd, span, spanEnd, break, breakEnd, group, groupBy, inits, tails, initsNE, tailsNE, stripPrefix, stripSuffix, -- ** Breaking into many substrings split, splitWith, -- * Predicates isPrefixOf, isSuffixOf, isInfixOf, -- ** Encoding validation isValidUtf8, -- ** Search for arbitrary substrings breakSubstring, -- * Searching ByteStrings -- ** Searching by equality elem, notElem, -- ** Searching with a predicate find, filter, partition, -- * Indexing ByteStrings index, indexMaybe, (!?), elemIndex, elemIndices, elemIndexEnd, findIndex, findIndices, findIndexEnd, count, -- * Zipping and unzipping ByteStrings zip, zipWith, packZipWith, unzip, -- * Ordered ByteStrings sort, -- * Low level conversions -- ** Copying ByteStrings copy, -- ** Packing 'CString's and pointers packCString, packCStringLen, -- ** Using ByteStrings as 'CString's useAsCString, useAsCStringLen, -- * I\/O with 'ByteString's -- ** Standard input and output getLine, getContents, putStr, interact, -- ** Files readFile, writeFile, appendFile, -- ** I\/O with Handles hGetLine, hGetContents, hGet, hGetSome, hGetNonBlocking, hPut, hPutNonBlocking, hPutStr, ) where import qualified Prelude as P import Prelude hiding (reverse,head,tail,last,init,null ,length,map,lines,foldl,foldr,unlines ,concat,any,take,drop,splitAt,takeWhile ,dropWhile,span,break,elem,filter,maximum ,minimum,all,concatMap,foldl1,foldr1 ,scanl,scanl1,scanr,scanr1 ,readFile,writeFile,appendFile,replicate ,getContents,getLine,putStr,putStrLn,interact ,zip,zipWith,unzip,notElem ) import Data.Bits (finiteBitSize, shiftL, (.|.), (.&.)) import Data.ByteString.Internal.Type import Data.ByteString.Lazy.Internal (fromStrict, toStrict) import Data.ByteString.Unsafe import qualified Data.List as List import qualified Data.List.NonEmpty as NE import Data.List.NonEmpty (NonEmpty(..)) import Data.Word (Word8) import Control.Exception (IOException, catch, finally, assert, throwIO) import Control.Monad (when, void) import Foreign.C.String (CString, CStringLen) import Foreign.C.Types (CSize (CSize), CInt (CInt)) import Foreign.ForeignPtr (ForeignPtr, touchForeignPtr) import Foreign.ForeignPtr.Unsafe(unsafeForeignPtrToPtr) import Foreign.Marshal.Alloc (allocaBytes) import Foreign.Marshal.Array (allocaArray) import Foreign.Ptr import Foreign.Storable (Storable(..)) -- hGetBuf and hPutBuf not available in yhc or nhc import System.IO (stdin,stdout,hClose,hFileSize ,hGetBuf,hPutBuf,hGetBufNonBlocking ,hPutBufNonBlocking,withBinaryFile ,IOMode(..),hGetBufSome) import System.IO.Error (mkIOError, illegalOperationErrorType) import Data.IORef import GHC.IO.Handle.Internals import GHC.IO.Handle.Types import GHC.IO.Buffer import GHC.IO.BufferedIO as Buffered import GHC.IO.Encoding (getFileSystemEncoding) import GHC.IO (unsafePerformIO, unsafeDupablePerformIO) import GHC.Foreign (newCStringLen, peekCStringLen) import GHC.Stack.Types (HasCallStack) import Data.Char (ord) import GHC.Base (build) import GHC.Word hiding (Word8) -- ----------------------------------------------------------------------------- -- Introducing and eliminating 'ByteString's -- | /O(1)/ Convert a 'Word8' into a 'ByteString' singleton :: Word8 -> ByteString -- Taking a slice of some static data rather than allocating a new -- buffer for each call is nice for several reasons. Since it doesn't -- involve any side effects hidden in a 'GHC.Magic.runRW#' call, it -- can be simplified to a constructor application. This may enable GHC -- to perform further optimizations after inlining, and also causes a -- fresh singleton to take only 4 words of heap space instead of 9. -- (The buffer object itself would take up 3 words: header, size, and -- 1 word of content. The ForeignPtrContents object used to keep the -- buffer alive would need two more.) singleton c = unsafeTake 1 $ unsafeDrop (fromIntegral c) allBytes {-# INLINE singleton #-} -- | A static blob of all possible bytes (0x00 to 0xff) in order allBytes :: ByteString allBytes = unsafePackLenLiteral 0x100 "\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f\x60\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f\x70\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7a\x7b\x7c\x7d\x7e\x7f\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff"# -- | /O(n)/ Convert a @['Word8']@ into a 'ByteString'. -- -- For applications with large numbers of string literals, 'pack' can be a -- bottleneck. In such cases, consider using 'unsafePackAddress' (GHC only). pack :: [Word8] -> ByteString pack = packBytes -- | /O(n)/ Converts a 'ByteString' to a @['Word8']@. unpack :: ByteString -> [Word8] unpack bs = build (unpackFoldr bs) {-# INLINE unpack #-} -- -- Have unpack fuse with good list consumers -- unpackFoldr :: ByteString -> (Word8 -> a -> a) -> a -> a unpackFoldr bs k z = foldr k z bs {-# INLINE [0] unpackFoldr #-} {-# RULES "ByteString unpack-list" [1] forall bs . unpackFoldr bs (:) [] = unpackBytes bs #-} -- | Convert a 'FilePath' to a 'ByteString'. -- -- The 'FilePath' type is expected to use the file system encoding -- as reported by 'GHC.IO.Encoding.getFileSystemEncoding'. This -- encoding allows for round-tripping of arbitrary data on platforms -- that allow arbitrary bytes in their paths. This conversion -- function does the same thing that `System.IO.openFile` would -- do when decoding the 'FilePath'. -- -- This function is in 'IO' because the file system encoding can be -- changed. If the encoding can be assumed to be constant in your -- use case, you may invoke this function via 'unsafePerformIO'. -- -- @since 0.11.2.0 fromFilePath :: FilePath -> IO ByteString fromFilePath path = do enc <- getFileSystemEncoding newCStringLen enc path >>= unsafePackMallocCStringLen -- | Convert a 'ByteString' to a 'FilePath'. -- -- This function uses the file system encoding, and resulting 'FilePath's -- can be safely used with standard IO functions and will reference the -- correct path in the presence of arbitrary non-UTF-8 encoded paths. -- -- This function is in 'IO' because the file system encoding can be -- changed. If the encoding can be assumed to be constant in your -- use case, you may invoke this function via 'unsafePerformIO'. -- -- @since 0.11.2.0 toFilePath :: ByteString -> IO FilePath toFilePath path = do enc <- getFileSystemEncoding useAsCStringLen path (peekCStringLen enc) -- --------------------------------------------------------------------- -- Basic interface -- | /O(1)/ Test whether a ByteString is empty. null :: ByteString -> Bool null (BS _ l) = assert (l >= 0) $ l <= 0 {-# INLINE null #-} -- --------------------------------------------------------------------- -- | /O(1)/ 'length' returns the length of a ByteString as an 'Int'. length :: ByteString -> Int length (BS _ l) = assert (l >= 0) l {-# INLINE length #-} ------------------------------------------------------------------------ infixr 5 `cons` --same as list (:) infixl 5 `snoc` -- | /O(n)/ 'cons' is analogous to (:) for lists, but of different -- complexity, as it requires making a copy. cons :: Word8 -> ByteString -> ByteString cons c (BS x l) = unsafeCreateFp (l+1) $ \p -> do pokeFp p c memcpyFp (p `plusForeignPtr` 1) x l {-# INLINE cons #-} -- | /O(n)/ Append a byte to the end of a 'ByteString' snoc :: ByteString -> Word8 -> ByteString snoc (BS x l) c = unsafeCreateFp (l+1) $ \p -> do memcpyFp p x l pokeFp (p `plusForeignPtr` l) c {-# INLINE snoc #-} -- | /O(1)/ Extract the first element of a ByteString, which must be non-empty. -- An exception will be thrown in the case of an empty ByteString. -- -- This is a partial function, consider using 'uncons' instead. head :: HasCallStack => ByteString -> Word8 head (BS x l) | l <= 0 = errorEmptyList "head" | otherwise = accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> peek p {-# INLINE head #-} -- | /O(1)/ Extract the elements after the head of a ByteString, which must be non-empty. -- An exception will be thrown in the case of an empty ByteString. -- -- This is a partial function, consider using 'uncons' instead. tail :: HasCallStack => ByteString -> ByteString tail (BS p l) | l <= 0 = errorEmptyList "tail" | otherwise = BS (plusForeignPtr p 1) (l-1) {-# INLINE tail #-} -- | /O(1)/ Extract the 'head' and 'tail' of a ByteString, returning 'Nothing' -- if it is empty. uncons :: ByteString -> Maybe (Word8, ByteString) uncons (BS x l) | l <= 0 = Nothing | otherwise = Just (accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> peek p, BS (plusForeignPtr x 1) (l-1)) {-# INLINE uncons #-} -- | /O(1)/ Extract the last element of a ByteString, which must be finite and non-empty. -- An exception will be thrown in the case of an empty ByteString. -- -- This is a partial function, consider using 'unsnoc' instead. last :: HasCallStack => ByteString -> Word8 last ps@(BS x l) | null ps = errorEmptyList "last" | otherwise = accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> peekByteOff p (l-1) {-# INLINE last #-} -- | /O(1)/ Returns all the elements of a 'ByteString' except the last one. -- An exception will be thrown in the case of an empty ByteString. -- -- This is a partial function, consider using 'unsnoc' instead. init :: HasCallStack => ByteString -> ByteString init ps@(BS p l) | null ps = errorEmptyList "init" | otherwise = BS p (l-1) {-# INLINE init #-} -- | /O(1)/ Extract the 'init' and 'last' of a ByteString, returning 'Nothing' -- if it is empty. unsnoc :: ByteString -> Maybe (ByteString, Word8) unsnoc (BS x l) | l <= 0 = Nothing | otherwise = Just (BS x (l-1), accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> peekByteOff p (l-1)) {-# INLINE unsnoc #-} -- | /O(n)/ Append two ByteStrings append :: ByteString -> ByteString -> ByteString append = mappend {-# INLINE append #-} -- --------------------------------------------------------------------- -- Transformations -- | /O(n)/ 'map' @f xs@ is the ByteString obtained by applying @f@ to each -- element of @xs@. map :: (Word8 -> Word8) -> ByteString -> ByteString map f (BS srcPtr len) = unsafeCreateFp len $ \dstPtr -> m srcPtr dstPtr where m !p1 !p2 = map_ 0 where map_ :: Int -> IO () map_ !n | n >= len = return () | otherwise = do x <- peekFpByteOff p1 n pokeFpByteOff p2 n (f x) map_ (n+1) {-# INLINE map #-} -- | /O(n)/ 'reverse' @xs@ efficiently returns the elements of @xs@ in reverse order. reverse :: ByteString -> ByteString reverse (BS x l) = unsafeCreateFp l $ \fp -> unsafeWithForeignPtr fp $ \p -> unsafeWithForeignPtr x $ \f -> c_reverse p f (fromIntegral l) -- | /O(n)/ The 'intersperse' function takes a 'Word8' and a -- 'ByteString' and \`intersperses\' that byte between the elements of -- the 'ByteString'. It is analogous to the intersperse function on -- Lists. intersperse :: Word8 -> ByteString -> ByteString intersperse c ps@(BS x l) | length ps < 2 = ps | otherwise = unsafeCreateFp (2*l-1) $ \fp -> unsafeWithForeignPtr fp $ \p -> unsafeWithForeignPtr x $ \f -> c_intersperse p f (fromIntegral l) c -- | The 'transpose' function transposes the rows and columns of its -- 'ByteString' argument. transpose :: [ByteString] -> [ByteString] transpose = P.map pack . List.transpose . P.map unpack -- --------------------------------------------------------------------- -- Reducing 'ByteString's -- | 'foldl', applied to a binary operator, a starting value (typically -- the left-identity of the operator), and a ByteString, reduces the -- ByteString using the binary operator, from left to right. -- foldl :: (a -> Word8 -> a) -> a -> ByteString -> a foldl f z = \(BS fp len) -> let end = unsafeForeignPtrToPtr fp `plusPtr` (-1) -- not tail recursive; traverses array right to left go !p | p == end = z | otherwise = let !x = accursedUnutterablePerformIO $ do x' <- peek p touchForeignPtr fp return x' in f (go (p `plusPtr` (-1))) x in go (end `plusPtr` len) {-# INLINE foldl #-} {- Note [fold inlining]: GHC will only inline a function marked INLINE if it is fully saturated (meaning the number of arguments provided at the call site is at least equal to the number of lhs arguments). -} -- | 'foldl'' is like 'foldl', but strict in the accumulator. -- foldl' :: (a -> Word8 -> a) -> a -> ByteString -> a foldl' f v = \(BS fp len) -> -- see fold inlining let g ptr = go v ptr where end = ptr `plusForeignPtr` len -- tail recursive; traverses array left to right go !z !p | p == end = return z | otherwise = do x <- peekFp p go (f z x) (p `plusForeignPtr` 1) in accursedUnutterablePerformIO $ g fp {-# INLINE foldl' #-} -- | 'foldr', applied to a binary operator, a starting value -- (typically the right-identity of the operator), and a ByteString, -- reduces the ByteString using the binary operator, from right to left. foldr :: (Word8 -> a -> a) -> a -> ByteString -> a foldr k z = \(BS fp len) -> -- see fold inlining let ptr = unsafeForeignPtrToPtr fp end = ptr `plusPtr` len -- not tail recursive; traverses array left to right go !p | p == end = z | otherwise = let !x = accursedUnutterablePerformIO $ do x' <- peek p touchForeignPtr fp return x' in k x (go (p `plusPtr` 1)) in go ptr {-# INLINE foldr #-} -- | 'foldr'' is like 'foldr', but strict in the accumulator. foldr' :: (Word8 -> a -> a) -> a -> ByteString -> a foldr' k v = \(BS fp len) -> -- see fold inlining let g ptr = go v (end `plusForeignPtr` len) where end = ptr `plusForeignPtr` (-1) -- tail recursive; traverses array right to left go !z !p | p == end = return z | otherwise = do x <- peekFp p go (k x z) (p `plusForeignPtr` (-1)) in accursedUnutterablePerformIO $ g fp {-# INLINE foldr' #-} -- | 'foldl1' is a variant of 'foldl' that has no starting value -- argument, and thus must be applied to non-empty 'ByteString's. -- An exception will be thrown in the case of an empty ByteString. foldl1 :: HasCallStack => (Word8 -> Word8 -> Word8) -> ByteString -> Word8 foldl1 f ps = case uncons ps of Nothing -> errorEmptyList "foldl1" Just (h, t) -> foldl f h t {-# INLINE foldl1 #-} -- | 'foldl1'' is like 'foldl1', but strict in the accumulator. -- An exception will be thrown in the case of an empty ByteString. foldl1' :: HasCallStack => (Word8 -> Word8 -> Word8) -> ByteString -> Word8 foldl1' f ps = case uncons ps of Nothing -> errorEmptyList "foldl1'" Just (h, t) -> foldl' f h t {-# INLINE foldl1' #-} -- | 'foldr1' is a variant of 'foldr' that has no starting value argument, -- and thus must be applied to non-empty 'ByteString's -- An exception will be thrown in the case of an empty ByteString. foldr1 :: HasCallStack => (Word8 -> Word8 -> Word8) -> ByteString -> Word8 foldr1 f ps = case unsnoc ps of Nothing -> errorEmptyList "foldr1" Just (b, c) -> foldr f c b {-# INLINE foldr1 #-} -- | 'foldr1'' is a variant of 'foldr1', but is strict in the -- accumulator. foldr1' :: HasCallStack => (Word8 -> Word8 -> Word8) -> ByteString -> Word8 foldr1' f ps = case unsnoc ps of Nothing -> errorEmptyList "foldr1'" Just (b, c) -> foldr' f c b {-# INLINE foldr1' #-} -- --------------------------------------------------------------------- -- Special folds -- | /O(n)/ Concatenate a list of ByteStrings. concat :: [ByteString] -> ByteString concat = mconcat -- | Map a function over a 'ByteString' and concatenate the results concatMap :: (Word8 -> ByteString) -> ByteString -> ByteString concatMap f = concat . foldr ((:) . f) [] -- foldr (append . f) empty -- | /O(n)/ Applied to a predicate and a ByteString, 'any' determines if -- any element of the 'ByteString' satisfies the predicate. any :: (Word8 -> Bool) -> ByteString -> Bool any _ (BS _ 0) = False any f (BS x len) = accursedUnutterablePerformIO $ g x where g ptr = go ptr where end = ptr `plusForeignPtr` len go !p | p == end = return False | otherwise = do c <- peekFp p if f c then return True else go (p `plusForeignPtr` 1) {-# INLINE [1] any #-} {-# RULES "ByteString specialise any (x ==)" forall x. any (x `eqWord8`) = anyByte x "ByteString specialise any (== x)" forall x. any (`eqWord8` x) = anyByte x #-} -- | Is any element of 'ByteString' equal to c? anyByte :: Word8 -> ByteString -> Bool anyByte c (BS x l) = accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> do q <- memchr p c (fromIntegral l) return $! q /= nullPtr {-# INLINE anyByte #-} -- | /O(n)/ Applied to a predicate and a 'ByteString', 'all' determines -- if all elements of the 'ByteString' satisfy the predicate. all :: (Word8 -> Bool) -> ByteString -> Bool all _ (BS _ 0) = True all f (BS x len) = accursedUnutterablePerformIO $ g x where g ptr = go ptr where end = ptr `plusForeignPtr` len go !p | p == end = return True -- end of list | otherwise = do c <- peekFp p if f c then go (p `plusForeignPtr` 1) else return False {-# INLINE [1] all #-} {-# RULES "ByteString specialise all (x /=)" forall x. all (x `neWord8`) = not . anyByte x "ByteString specialise all (/= x)" forall x. all (`neWord8` x) = not . anyByte x #-} ------------------------------------------------------------------------ -- | /O(n)/ 'maximum' returns the maximum value from a 'ByteString' -- An exception will be thrown in the case of an empty ByteString. maximum :: HasCallStack => ByteString -> Word8 maximum xs@(BS x l) | null xs = errorEmptyList "maximum" | otherwise = accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> c_maximum p (fromIntegral l) {-# INLINE maximum #-} -- | /O(n)/ 'minimum' returns the minimum value from a 'ByteString' -- An exception will be thrown in the case of an empty ByteString. minimum :: HasCallStack => ByteString -> Word8 minimum xs@(BS x l) | null xs = errorEmptyList "minimum" | otherwise = accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> c_minimum p (fromIntegral l) {-# INLINE minimum #-} ------------------------------------------------------------------------ -- | The 'mapAccumL' function behaves like a combination of 'map' and -- 'foldl'; it applies a function to each element of a ByteString, -- passing an accumulating parameter from left to right, and returning a -- final value of this accumulator together with the new ByteString. mapAccumL :: (acc -> Word8 -> (acc, Word8)) -> acc -> ByteString -> (acc, ByteString) mapAccumL f acc = \(BS a len) -> unsafeDupablePerformIO $ do -- see fold inlining gp <- mallocByteString len let go src dst = mapAccumL_ acc 0 where mapAccumL_ !s !n | n >= len = return s | otherwise = do x <- peekFpByteOff src n let (s', y) = f s x pokeFpByteOff dst n y mapAccumL_ s' (n+1) acc' <- go a gp return (acc', BS gp len) {-# INLINE mapAccumL #-} -- | The 'mapAccumR' function behaves like a combination of 'map' and -- 'foldr'; it applies a function to each element of a ByteString, -- passing an accumulating parameter from right to left, and returning a -- final value of this accumulator together with the new ByteString. mapAccumR :: (acc -> Word8 -> (acc, Word8)) -> acc -> ByteString -> (acc, ByteString) mapAccumR f acc = \(BS a len) -> unsafeDupablePerformIO $ do -- see fold inlining gp <- mallocByteString len let go src dst = mapAccumR_ acc (len-1) where mapAccumR_ !s (-1) = return s mapAccumR_ !s !n = do x <- peekFpByteOff src n let (s', y) = f s x pokeFpByteOff dst n y mapAccumR_ s' (n-1) acc' <- go a gp return (acc', BS gp len) {-# INLINE mapAccumR #-} -- --------------------------------------------------------------------- -- Building ByteStrings -- | 'scanl' is similar to 'foldl', but returns a list of successive -- reduced values from the left. -- -- > scanl f z [x1, x2, ...] == [z, z `f` x1, (z `f` x1) `f` x2, ...] -- -- Note that -- -- > head (scanl f z xs) == z -- > last (scanl f z xs) == foldl f z xs -- scanl :: (Word8 -> Word8 -> Word8) -- ^ accumulator -> element -> new accumulator -> Word8 -- ^ starting value of accumulator -> ByteString -- ^ input of length n -> ByteString -- ^ output of length n+1 scanl f v = \(BS a len) -> unsafeCreateFp (len+1) $ \q -> do -- see fold inlining pokeFp q v let go src dst = scanl_ v 0 where scanl_ !z !n | n >= len = return () | otherwise = do x <- peekFpByteOff src n let z' = f z x pokeFpByteOff dst n z' scanl_ z' (n+1) go a (q `plusForeignPtr` 1) {-# INLINE scanl #-} -- | 'scanl1' is a variant of 'scanl' that has no starting value argument. -- -- > scanl1 f [x1, x2, ...] == [x1, x1 `f` x2, ...] scanl1 :: (Word8 -> Word8 -> Word8) -> ByteString -> ByteString scanl1 f ps = case uncons ps of Nothing -> empty Just (h, t) -> scanl f h t {-# INLINE scanl1 #-} -- | 'scanr' is similar to 'foldr', but returns a list of successive -- reduced values from the right. -- -- > scanr f z [..., x{n-1}, xn] == [..., x{n-1} `f` (xn `f` z), xn `f` z, z] -- -- Note that -- -- > head (scanr f z xs) == foldr f z xs -- > last (scanr f z xs) == z -- scanr :: (Word8 -> Word8 -> Word8) -- ^ element -> accumulator -> new accumulator -> Word8 -- ^ starting value of accumulator -> ByteString -- ^ input of length n -> ByteString -- ^ output of length n+1 scanr f v = \(BS a len) -> unsafeCreateFp (len+1) $ \b -> do -- see fold inlining pokeFpByteOff b len v let go p q = scanr_ v (len-1) where scanr_ !z !n | n < 0 = return () | otherwise = do x <- peekFpByteOff p n let z' = f x z pokeFpByteOff q n z' scanr_ z' (n-1) go a b {-# INLINE scanr #-} -- | 'scanr1' is a variant of 'scanr' that has no starting value argument. scanr1 :: (Word8 -> Word8 -> Word8) -> ByteString -> ByteString scanr1 f ps = case unsnoc ps of Nothing -> empty Just (b, c) -> scanr f c b {-# INLINE scanr1 #-} -- --------------------------------------------------------------------- -- Unfolds and replicates -- | /O(n)/ 'replicate' @n x@ is a ByteString of length @n@ with @x@ -- the value of every element. The following holds: -- -- > replicate w c = unfoldr w (\u -> Just (u,u)) c -- -- This implementation uses @memset(3)@ replicate :: Int -> Word8 -> ByteString replicate w c | w <= 0 = empty | otherwise = unsafeCreateFp w $ \fptr -> unsafeWithForeignPtr fptr $ \ptr -> void $ memset ptr c (fromIntegral w) {-# INLINE replicate #-} -- | /O(n)/, where /n/ is the length of the result. The 'unfoldr' -- function is analogous to the List \'unfoldr\'. 'unfoldr' builds a -- ByteString from a seed value. The function takes the element and -- returns 'Nothing' if it is done producing the ByteString or returns -- 'Just' @(a,b)@, in which case, @a@ is the next byte in the string, -- and @b@ is the seed value for further production. -- -- Examples: -- -- > unfoldr (\x -> if x <= 5 then Just (x, x + 1) else Nothing) 0 -- > == pack [0, 1, 2, 3, 4, 5] -- unfoldr :: (a -> Maybe (Word8, a)) -> a -> ByteString unfoldr f = concat . unfoldChunk 32 64 where unfoldChunk n n' x = case unfoldrN n f x of (s, Nothing) -> [s] (s, Just x') -> s : unfoldChunk n' (n+n') x' {-# INLINE unfoldr #-} -- | /O(n)/ Like 'unfoldr', 'unfoldrN' builds a ByteString from a seed -- value. However, the length of the result is limited by the first -- argument to 'unfoldrN'. This function is more efficient than 'unfoldr' -- when the maximum length of the result is known. -- -- The following equation relates 'unfoldrN' and 'unfoldr': -- -- > fst (unfoldrN n f s) == take n (unfoldr f s) -- unfoldrN :: Int -> (a -> Maybe (Word8, a)) -> a -> (ByteString, Maybe a) unfoldrN i f x0 | i < 0 = (empty, Just x0) | otherwise = unsafePerformIO $ createFpAndTrim' i $ \p -> go p x0 0 where go !p !x !n = go' x n where go' !x' !n' | n' == i = return (0, n', Just x') | otherwise = case f x' of Nothing -> return (0, n', Nothing) Just (w,x'') -> do pokeFpByteOff p n' w go' x'' (n'+1) {-# INLINE unfoldrN #-} -- --------------------------------------------------------------------- -- Substrings -- | /O(1)/ 'take' @n@, applied to a ByteString @xs@, returns the prefix -- of @xs@ of length @n@, or @xs@ itself if @n > 'length' xs@. take :: Int -> ByteString -> ByteString take n ps@(BS x l) | n <= 0 = empty | n >= l = ps | otherwise = BS x n {-# INLINE take #-} -- | /O(1)/ @'takeEnd' n xs@ is equivalent to @'drop' ('length' xs - n) xs@. -- Takes @n@ elements from end of bytestring. -- -- >>> takeEnd 3 "abcdefg" -- "efg" -- >>> takeEnd 0 "abcdefg" -- "" -- >>> takeEnd 4 "abc" -- "abc" -- -- @since 0.11.1.0 takeEnd :: Int -> ByteString -> ByteString takeEnd n ps@(BS x len) | n >= len = ps | n <= 0 = empty | otherwise = BS (plusForeignPtr x (len - n)) n {-# INLINE takeEnd #-} -- | /O(1)/ 'drop' @n xs@ returns the suffix of @xs@ after the first @n@ -- elements, or 'empty' if @n > 'length' xs@. drop :: Int -> ByteString -> ByteString drop n ps@(BS x l) | n <= 0 = ps | n >= l = empty | otherwise = BS (plusForeignPtr x n) (l-n) {-# INLINE drop #-} -- | /O(1)/ @'dropEnd' n xs@ is equivalent to @'take' ('length' xs - n) xs@. -- Drops @n@ elements from end of bytestring. -- -- >>> dropEnd 3 "abcdefg" -- "abcd" -- >>> dropEnd 0 "abcdefg" -- "abcdefg" -- >>> dropEnd 4 "abc" -- "" -- -- @since 0.11.1.0 dropEnd :: Int -> ByteString -> ByteString dropEnd n ps@(BS x len) | n <= 0 = ps | n >= len = empty | otherwise = BS x (len - n) {-# INLINE dropEnd #-} -- | /O(1)/ 'splitAt' @n xs@ is equivalent to @('take' n xs, 'drop' n xs)@. splitAt :: Int -> ByteString -> (ByteString, ByteString) splitAt n ps@(BS x l) | n <= 0 = (empty, ps) | n >= l = (ps, empty) | otherwise = (BS x n, BS (plusForeignPtr x n) (l-n)) {-# INLINE splitAt #-} -- | Similar to 'Prelude.takeWhile', -- returns the longest (possibly empty) prefix of elements -- satisfying the predicate. takeWhile :: (Word8 -> Bool) -> ByteString -> ByteString takeWhile f ps = unsafeTake (findIndexOrLength (not . f) ps) ps {-# INLINE [1] takeWhile #-} {-# RULES "ByteString specialise takeWhile (x /=)" forall x. takeWhile (x `neWord8`) = fst . breakByte x "ByteString specialise takeWhile (/= x)" forall x. takeWhile (`neWord8` x) = fst . breakByte x "ByteString specialise takeWhile (x ==)" forall x. takeWhile (x `eqWord8`) = fst . spanByte x "ByteString specialise takeWhile (== x)" forall x. takeWhile (`eqWord8` x) = fst . spanByte x #-} -- | Returns the longest (possibly empty) suffix of elements -- satisfying the predicate. -- -- @'takeWhileEnd' p@ is equivalent to @'reverse' . 'takeWhile' p . 'reverse'@. -- -- @since 0.10.12.0 takeWhileEnd :: (Word8 -> Bool) -> ByteString -> ByteString takeWhileEnd f ps = unsafeDrop (findFromEndUntil (not . f) ps) ps {-# INLINE takeWhileEnd #-} -- | Similar to 'Prelude.dropWhile', -- drops the longest (possibly empty) prefix of elements -- satisfying the predicate and returns the remainder. dropWhile :: (Word8 -> Bool) -> ByteString -> ByteString dropWhile f ps = unsafeDrop (findIndexOrLength (not . f) ps) ps {-# INLINE [1] dropWhile #-} {-# RULES "ByteString specialise dropWhile (x /=)" forall x. dropWhile (x `neWord8`) = snd . breakByte x "ByteString specialise dropWhile (/= x)" forall x. dropWhile (`neWord8` x) = snd . breakByte x "ByteString specialise dropWhile (x ==)" forall x. dropWhile (x `eqWord8`) = snd . spanByte x "ByteString specialise dropWhile (== x)" forall x. dropWhile (`eqWord8` x) = snd . spanByte x #-} -- | Similar to 'Prelude.dropWhileEnd', -- drops the longest (possibly empty) suffix of elements -- satisfying the predicate and returns the remainder. -- -- @'dropWhileEnd' p@ is equivalent to @'reverse' . 'dropWhile' p . 'reverse'@. -- -- @since 0.10.12.0 dropWhileEnd :: (Word8 -> Bool) -> ByteString -> ByteString dropWhileEnd f ps = unsafeTake (findFromEndUntil (not . f) ps) ps {-# INLINE dropWhileEnd #-} -- | Similar to 'Prelude.break', -- returns the longest (possibly empty) prefix of elements which __do not__ -- satisfy the predicate and the remainder of the string. -- -- 'break' @p@ is equivalent to @'span' (not . p)@ and to @('takeWhile' (not . p) &&& 'dropWhile' (not . p))@. -- -- Under GHC, a rewrite rule will transform break (==) into a -- call to the specialised breakByte: -- -- > break ((==) x) = breakByte x -- > break (==x) = breakByte x -- break :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString) break p ps = case findIndexOrLength p ps of n -> (unsafeTake n ps, unsafeDrop n ps) {-# INLINE [1] break #-} -- See bytestring #70 {-# RULES "ByteString specialise break (x ==)" forall x. break (x `eqWord8`) = breakByte x "ByteString specialise break (== x)" forall x. break (`eqWord8` x) = breakByte x #-} -- INTERNAL: -- | 'breakByte' breaks its ByteString argument at the first occurrence -- of the specified byte. It is more efficient than 'break' as it is -- implemented with @memchr(3)@. I.e. -- -- > break (==99) "abcd" == breakByte 99 "abcd" -- fromEnum 'c' == 99 -- breakByte :: Word8 -> ByteString -> (ByteString, ByteString) breakByte c p = case elemIndex c p of Nothing -> (p,empty) Just n -> (unsafeTake n p, unsafeDrop n p) {-# INLINE breakByte #-} -- | Returns the longest (possibly empty) suffix of elements which __do not__ -- satisfy the predicate and the remainder of the string. -- -- 'breakEnd' @p@ is equivalent to @'spanEnd' (not . p)@ and to @('takeWhileEnd' (not . p) &&& 'dropWhileEnd' (not . p))@. -- breakEnd :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString) breakEnd p ps = splitAt (findFromEndUntil p ps) ps -- | Similar to 'Prelude.span', -- returns the longest (possibly empty) prefix of elements -- satisfying the predicate and the remainder of the string. -- -- 'span' @p@ is equivalent to @'break' (not . p)@ and to @('takeWhile' p &&& 'dropWhile' p)@. -- span :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString) span p = break (not . p) {-# INLINE [1] span #-} -- | 'spanByte' breaks its ByteString argument at the first -- occurrence of a byte other than its argument. It is more efficient -- than 'span (==)' -- -- > span (==99) "abcd" == spanByte 99 "abcd" -- fromEnum 'c' == 99 -- spanByte :: Word8 -> ByteString -> (ByteString, ByteString) spanByte c ps@(BS x l) = accursedUnutterablePerformIO $ unsafeWithForeignPtr x g where g p = go 0 where go !i | i >= l = return (ps, empty) | otherwise = do c' <- peekByteOff p i if c /= c' then return (unsafeTake i ps, unsafeDrop i ps) else go (i+1) {-# INLINE spanByte #-} -- See bytestring #70 {-# RULES "ByteString specialise span (x ==)" forall x. span (x `eqWord8`) = spanByte x "ByteString specialise span (== x)" forall x. span (`eqWord8` x) = spanByte x #-} -- | Returns the longest (possibly empty) suffix of elements -- satisfying the predicate and the remainder of the string. -- -- 'spanEnd' @p@ is equivalent to @'breakEnd' (not . p)@ and to @('takeWhileEnd' p &&& 'dropWhileEnd' p)@. -- -- We have -- -- > spanEnd (not . isSpace) "x y z" == ("x y ", "z") -- -- and -- -- > spanEnd (not . isSpace) ps -- > == -- > let (x, y) = span (not . isSpace) (reverse ps) in (reverse y, reverse x) -- spanEnd :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString) spanEnd p ps = splitAt (findFromEndUntil (not.p) ps) ps -- | /O(n)/ Splits a 'ByteString' into components delimited by -- separators, where the predicate returns True for a separator element. -- The resulting components do not contain the separators. Two adjacent -- separators result in an empty component in the output. eg. -- -- > splitWith (==97) "aabbaca" == ["","","bb","c",""] -- fromEnum 'a' == 97 -- > splitWith undefined "" == [] -- and not [""] -- splitWith :: (Word8 -> Bool) -> ByteString -> [ByteString] splitWith _ (BS _ 0) = [] splitWith predicate (BS fp len) = splitWith0 0 len fp where splitWith0 !off' !len' !fp' = accursedUnutterablePerformIO $ splitLoop fp 0 off' len' fp' splitLoop :: ForeignPtr Word8 -> Int -> Int -> Int -> ForeignPtr Word8 -> IO [ByteString] splitLoop p idx2 off' len' fp' = go idx2 where go idx' | idx' >= len' = return [BS (plusForeignPtr fp' off') idx'] | otherwise = do w <- peekFpByteOff p (off'+idx') if predicate w then return (BS (plusForeignPtr fp' off') idx' : splitWith0 (off'+idx'+1) (len'-idx'-1) fp') else go (idx'+1) {-# INLINE splitWith #-} -- | /O(n)/ Break a 'ByteString' into pieces separated by the byte -- argument, consuming the delimiter. I.e. -- -- > split 10 "a\nb\nd\ne" == ["a","b","d","e"] -- fromEnum '\n' == 10 -- > split 97 "aXaXaXa" == ["","X","X","X",""] -- fromEnum 'a' == 97 -- > split 120 "x" == ["",""] -- fromEnum 'x' == 120 -- > split undefined "" == [] -- and not [""] -- -- and -- -- > intercalate [c] . split c == id -- > split == splitWith . (==) -- -- As for all splitting functions in this library, this function does -- not copy the substrings, it just constructs new 'ByteString's that -- are slices of the original. -- split :: Word8 -> ByteString -> [ByteString] split _ (BS _ 0) = [] split w (BS x l) = loop 0 where loop !n = let q = accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> memchr (p `plusPtr` n) w (fromIntegral (l-n)) in if q == nullPtr then [BS (plusForeignPtr x n) (l-n)] else let i = q `minusPtr` unsafeForeignPtrToPtr x in BS (plusForeignPtr x n) (i-n) : loop (i+1) {-# INLINE split #-} -- | The 'group' function takes a ByteString and returns a list of -- ByteStrings such that the concatenation of the result is equal to the -- argument. Moreover, each string in the result contains only equal -- elements. For example, -- -- > group "Mississippi" = ["M","i","ss","i","ss","i","pp","i"] -- -- It is a special case of 'groupBy', which allows the programmer to -- supply their own equality test. It is about 40% faster than -- /groupBy (==)/ group :: ByteString -> [ByteString] group xs = case uncons xs of Nothing -> [] Just (h, _) -> ys : group zs where (ys, zs) = spanByte h xs -- | The 'groupBy' function is the non-overloaded version of 'group'. groupBy :: (Word8 -> Word8 -> Bool) -> ByteString -> [ByteString] groupBy k xs = case uncons xs of Nothing -> [] Just (h, t) -> unsafeTake n xs : groupBy k (unsafeDrop n xs) where n = 1 + findIndexOrLength (not . k h) t -- | /O(n)/ The 'intercalate' function takes a 'ByteString' and a list of -- 'ByteString's and concatenates the list after interspersing the first -- argument between each element of the list. intercalate :: ByteString -> [ByteString] -> ByteString intercalate _ [] = mempty intercalate _ [x] = x -- This branch exists for laziness, not speed intercalate (BS sepPtr sepLen) (BS hPtr hLen : t) = unsafeCreateFp totalLen $ \dstPtr0 -> do memcpyFp dstPtr0 hPtr hLen let go _ [] = pure () go dstPtr (BS chunkPtr chunkLen : chunks) = do memcpyFp dstPtr sepPtr sepLen let destPtr' = dstPtr `plusForeignPtr` sepLen memcpyFp destPtr' chunkPtr chunkLen go (destPtr' `plusForeignPtr` chunkLen) chunks go (dstPtr0 `plusForeignPtr` hLen) t where totalLen = List.foldl' (\acc (BS _ chunkLen) -> acc + chunkLen + sepLen) hLen t {-# INLINE intercalate #-} -- --------------------------------------------------------------------- -- Indexing ByteStrings -- | /O(1)/ 'ByteString' index (subscript) operator, starting from 0. -- -- This is a partial function, consider using 'indexMaybe' instead. index :: HasCallStack => ByteString -> Int -> Word8 index ps n | n < 0 = moduleError "index" ("negative index: " ++ show n) | n >= length ps = moduleError "index" ("index too large: " ++ show n ++ ", length = " ++ show (length ps)) | otherwise = ps `unsafeIndex` n {-# INLINE index #-} -- | /O(1)/ 'ByteString' index, starting from 0, that returns 'Just' if: -- -- > 0 <= n < length bs -- -- @since 0.11.0.0 indexMaybe :: ByteString -> Int -> Maybe Word8 indexMaybe ps n | n < 0 = Nothing | n >= length ps = Nothing | otherwise = Just $! ps `unsafeIndex` n {-# INLINE indexMaybe #-} -- | /O(1)/ 'ByteString' index, starting from 0, that returns 'Just' if: -- -- > 0 <= n < length bs -- -- @since 0.11.0.0 (!?) :: ByteString -> Int -> Maybe Word8 (!?) = indexMaybe {-# INLINE (!?) #-} -- | /O(n)/ The 'elemIndex' function returns the index of the first -- element in the given 'ByteString' which is equal to the query -- element, or 'Nothing' if there is no such element. -- This implementation uses memchr(3). elemIndex :: Word8 -> ByteString -> Maybe Int elemIndex c (BS x l) = accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> do q <- memchr p c (fromIntegral l) return $! if q == nullPtr then Nothing else Just $! q `minusPtr` p {-# INLINE elemIndex #-} -- | /O(n)/ The 'elemIndexEnd' function returns the last index of the -- element in the given 'ByteString' which is equal to the query -- element, or 'Nothing' if there is no such element. The following -- holds: -- -- > elemIndexEnd c xs = case elemIndex c (reverse xs) of -- > Nothing -> Nothing -- > Just i -> Just (length xs - 1 - i) -- elemIndexEnd :: Word8 -> ByteString -> Maybe Int elemIndexEnd = findIndexEnd . (==) {-# INLINE elemIndexEnd #-} -- | /O(n)/ The 'elemIndices' function extends 'elemIndex', by returning -- the indices of all elements equal to the query element, in ascending order. -- This implementation uses memchr(3). elemIndices :: Word8 -> ByteString -> [Int] elemIndices w (BS x l) = loop 0 where loop !n = accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> do q <- memchr (p `plusPtr` n) w (fromIntegral (l - n)) if q == nullPtr then return [] else let !i = q `minusPtr` p in return $ i : loop (i + 1) {-# INLINE elemIndices #-} -- | count returns the number of times its argument appears in the ByteString -- -- > count = length . elemIndices -- -- But more efficiently than using length on the intermediate list. count :: Word8 -> ByteString -> Int count w (BS x m) = accursedUnutterablePerformIO $ unsafeWithForeignPtr x $ \p -> fromIntegral <$> c_count p (fromIntegral m) w {-# INLINE count #-} -- | /O(n)/ The 'findIndex' function takes a predicate and a 'ByteString' and -- returns the index of the first element in the ByteString -- satisfying the predicate. findIndex :: (Word8 -> Bool) -> ByteString -> Maybe Int findIndex k (BS x l) = accursedUnutterablePerformIO $ g x where g !ptr = go 0 where go !n | n >= l = return Nothing | otherwise = do w <- peekFp $ ptr `plusForeignPtr` n if k w then return (Just n) else go (n+1) {-# INLINE [1] findIndex #-} -- | /O(n)/ The 'findIndexEnd' function takes a predicate and a 'ByteString' and -- returns the index of the last element in the ByteString -- satisfying the predicate. -- -- @since 0.10.12.0 findIndexEnd :: (Word8 -> Bool) -> ByteString -> Maybe Int findIndexEnd k (BS x l) = accursedUnutterablePerformIO $ g x where g !ptr = go (l-1) where go !n | n < 0 = return Nothing | otherwise = do w <- peekFpByteOff ptr n if k w then return (Just n) else go (n-1) {-# INLINE findIndexEnd #-} -- | /O(n)/ The 'findIndices' function extends 'findIndex', by returning the -- indices of all elements satisfying the predicate, in ascending order. findIndices :: (Word8 -> Bool) -> ByteString -> [Int] findIndices p = loop 0 where loop !n !qs = case findIndex p qs of Just !i -> let !j = n+i in j : loop (j+1) (unsafeDrop (i+1) qs) Nothing -> [] {-# INLINE [1] findIndices #-} {-# RULES "ByteString specialise findIndex (x ==)" forall x. findIndex (x`eqWord8`) = elemIndex x "ByteString specialise findIndex (== x)" forall x. findIndex (`eqWord8`x) = elemIndex x "ByteString specialise findIndices (x ==)" forall x. findIndices (x`eqWord8`) = elemIndices x "ByteString specialise findIndices (== x)" forall x. findIndices (`eqWord8`x) = elemIndices x #-} -- --------------------------------------------------------------------- -- Searching ByteStrings -- | /O(n)/ 'elem' is the 'ByteString' membership predicate. elem :: Word8 -> ByteString -> Bool elem c ps = case elemIndex c ps of Nothing -> False ; _ -> True {-# INLINE elem #-} -- | /O(n)/ 'notElem' is the inverse of 'elem' notElem :: Word8 -> ByteString -> Bool notElem c ps = not (c `elem` ps) {-# INLINE notElem #-} -- | /O(n)/ 'filter', applied to a predicate and a ByteString, -- returns a ByteString containing those characters that satisfy the -- predicate. filter :: (Word8 -> Bool) -> ByteString -> ByteString filter k = \ps@(BS pIn l) -> -- see fold inlining. if null ps then ps else unsafeDupablePerformIO $ createFpAndTrim l $ \pOut -> do let go' pf pt = go pf pt where end = pf `plusForeignPtr` l go !f !t | f == end = return t | otherwise = do w <- peekFp f if k w then pokeFp t w >> go (f `plusForeignPtr` 1) (t `plusForeignPtr` 1) else go (f `plusForeignPtr` 1) t t <- go' pIn pOut return $! t `minusForeignPtr` pOut -- actual length {-# INLINE filter #-} {- -- -- | /O(n)/ A first order equivalent of /filter . (==)/, for the common -- case of filtering a single byte. It is more efficient to use -- /filterByte/ in this case. -- -- > filterByte == filter . (==) -- -- filterByte is around 10x faster, and uses much less space, than its -- filter equivalent -- filterByte :: Word8 -> ByteString -> ByteString filterByte w ps = replicate (count w ps) w {-# INLINE filterByte #-} {-# RULES "ByteString specialise filter (== x)" forall x. filter ((==) x) = filterByte x "ByteString specialise filter (== x)" forall x. filter (== x) = filterByte x #-} -} -- | /O(n)/ The 'find' function takes a predicate and a ByteString, -- and returns the first element in matching the predicate, or 'Nothing' -- if there is no such element. -- -- > find f p = case findIndex f p of Just n -> Just (p ! n) ; _ -> Nothing -- find :: (Word8 -> Bool) -> ByteString -> Maybe Word8 find f p = case findIndex f p of Just n -> Just (p `unsafeIndex` n) _ -> Nothing {-# INLINE find #-} -- | /O(n)/ The 'partition' function takes a predicate a ByteString and returns -- the pair of ByteStrings with elements which do and do not satisfy the -- predicate, respectively; i.e., -- -- > partition p bs == (filter p xs, filter (not . p) xs) -- partition :: (Word8 -> Bool) -> ByteString -> (ByteString, ByteString) partition f s = unsafeDupablePerformIO $ do p <- mallocByteString len let end = p `plusForeignPtr` (len - 1) mid <- sep 0 p end rev mid end let i = mid `minusForeignPtr` p return (BS p i, BS (p `plusForeignPtr` i) (len - i)) where len = length s incr = (`plusForeignPtr` 1) decr = (`plusForeignPtr` (-1)) sep !i !p1 !p2 | i == len = return p1 | f w = do pokeFp p1 w sep (i + 1) (incr p1) p2 | otherwise = do pokeFp p2 w sep (i + 1) p1 (decr p2) where w = s `unsafeIndex` i rev !p1 !p2 -- fixme: surely there are faster ways to do this | p1 >= p2 = return () | otherwise = do a <- peekFp p1 b <- peekFp p2 pokeFp p1 b pokeFp p2 a rev (incr p1) (decr p2) -- -------------------------------------------------------------------- -- Sarching for substrings -- |/O(n)/ The 'isPrefixOf' function takes two ByteStrings and returns 'True' -- if the first is a prefix of the second. isPrefixOf :: ByteString -> ByteString -> Bool isPrefixOf (BS x1 l1) (BS x2 l2) | l1 == 0 = True | l2 < l1 = False | otherwise = accursedUnutterablePerformIO $ unsafeWithForeignPtr x1 $ \p1 -> unsafeWithForeignPtr x2 $ \p2 -> do i <- memcmp p1 p2 (fromIntegral l1) return $! i == 0 -- | /O(n)/ The 'stripPrefix' function takes two ByteStrings and returns 'Just' -- the remainder of the second iff the first is its prefix, and otherwise -- 'Nothing'. -- -- @since 0.10.8.0 stripPrefix :: ByteString -> ByteString -> Maybe ByteString stripPrefix bs1@(BS _ l1) bs2 | bs1 `isPrefixOf` bs2 = Just (unsafeDrop l1 bs2) | otherwise = Nothing -- | /O(n)/ The 'isSuffixOf' function takes two ByteStrings and returns 'True' -- iff the first is a suffix of the second. -- -- The following holds: -- -- > isSuffixOf x y == reverse x `isPrefixOf` reverse y -- -- However, the real implementation uses memcmp to compare the end of the -- string only, with no reverse required.. isSuffixOf :: ByteString -> ByteString -> Bool isSuffixOf (BS x1 l1) (BS x2 l2) | l1 == 0 = True | l2 < l1 = False | otherwise = accursedUnutterablePerformIO $ unsafeWithForeignPtr x1 $ \p1 -> unsafeWithForeignPtr x2 $ \p2 -> do i <- memcmp p1 (p2 `plusPtr` (l2 - l1)) (fromIntegral l1) return $! i == 0 -- | /O(n)/ The 'stripSuffix' function takes two ByteStrings and returns 'Just' -- the remainder of the second iff the first is its suffix, and otherwise -- 'Nothing'. stripSuffix :: ByteString -> ByteString -> Maybe ByteString stripSuffix bs1@(BS _ l1) bs2@(BS _ l2) | bs1 `isSuffixOf` bs2 = Just (unsafeTake (l2 - l1) bs2) | otherwise = Nothing -- | Check whether one string is a substring of another. isInfixOf :: ByteString -> ByteString -> Bool isInfixOf p s = null p || not (null $ snd $ breakSubstring p s) -- | /O(n)/ Check whether a 'ByteString' represents valid UTF-8. -- -- @since 0.11.2.0 isValidUtf8 :: ByteString -> Bool isValidUtf8 (BS ptr len) = accursedUnutterablePerformIO $ unsafeWithForeignPtr ptr $ \p -> do -- Use a safe FFI call for large inputs to avoid GC synchronization pauses -- in multithreaded contexts. -- This specific limit was chosen based on results of a simple benchmark, see: -- https://github.com/haskell/bytestring/issues/451#issuecomment-991879338 -- When changing this function, also consider changing the related function: -- Data.ByteString.Short.Internal.isValidUtf8 i <- if len < 1000000 then cIsValidUtf8 p (fromIntegral len) else cIsValidUtf8Safe p (fromIntegral len) pure $ i /= 0 -- We import bytestring_is_valid_utf8 both unsafe and safe. For small inputs -- we can use the unsafe version to get a bit more performance, but for large -- inputs the safe version should be used to avoid GC synchronization pauses -- in multithreaded contexts. foreign import ccall unsafe "bytestring_is_valid_utf8" cIsValidUtf8 :: Ptr Word8 -> CSize -> IO CInt foreign import ccall safe "bytestring_is_valid_utf8" cIsValidUtf8Safe :: Ptr Word8 -> CSize -> IO CInt -- | Break a string on a substring, returning a pair of the part of the -- string prior to the match, and the rest of the string. -- -- The following relationships hold: -- -- > break (== c) l == breakSubstring (singleton c) l -- -- For example, to tokenise a string, dropping delimiters: -- -- > tokenise x y = h : if null t then [] else tokenise x (drop (length x) t) -- > where (h,t) = breakSubstring x y -- -- To skip to the first occurrence of a string: -- -- > snd (breakSubstring x y) -- -- To take the parts of a string before a delimiter: -- -- > fst (breakSubstring x y) -- -- Note that calling `breakSubstring x` does some preprocessing work, so -- you should avoid unnecessarily duplicating breakSubstring calls with the same -- pattern. -- breakSubstring :: ByteString -- ^ String to search for -> ByteString -- ^ String to search in -> (ByteString,ByteString) -- ^ Head and tail of string broken at substring breakSubstring pat = case lp of 0 -> (empty,) 1 -> breakByte (unsafeHead pat) _ -> if lp * 8 <= finiteBitSize (0 :: Word) then shift else karpRabin where unsafeSplitAt i s = (unsafeTake i s, unsafeDrop i s) lp = length pat karpRabin :: ByteString -> (ByteString, ByteString) karpRabin src | length src < lp = (src,empty) | otherwise = search (rollingHash $ unsafeTake lp src) lp where k = 2891336453 :: Word32 rollingHash = foldl' (\h b -> h * k + fromIntegral b) 0 hp = rollingHash pat m = k ^ lp get = fromIntegral . unsafeIndex src search !hs !i | hp == hs && pat == unsafeTake lp b = u | length src <= i = (src,empty) -- not found | otherwise = search hs' (i + 1) where u@(_, b) = unsafeSplitAt (i - lp) src hs' = hs * k + get i - m * get (i - lp) {-# INLINE karpRabin #-} shift :: ByteString -> (ByteString, ByteString) shift !src | length src < lp = (src,empty) | otherwise = search (intoWord $ unsafeTake lp src) lp where intoWord :: ByteString -> Word intoWord = foldl' (\w b -> (w `shiftL` 8) .|. fromIntegral b) 0 wp = intoWord pat mask = (1 `shiftL` (8 * lp)) - 1 search !w !i | w == wp = unsafeSplitAt (i - lp) src | length src <= i = (src, empty) | otherwise = search w' (i + 1) where b = fromIntegral (unsafeIndex src i) w' = mask .&. ((w `shiftL` 8) .|. b) {-# INLINE shift #-} -- --------------------------------------------------------------------- -- Zipping -- | /O(n)/ 'zip' takes two ByteStrings and returns a list of -- corresponding pairs of bytes. If one input ByteString is short, -- excess elements of the longer ByteString are discarded. This is -- equivalent to a pair of 'unpack' operations. zip :: ByteString -> ByteString -> [(Word8,Word8)] zip ps qs = case uncons ps of Nothing -> [] Just (psH, psT) -> case uncons qs of Nothing -> [] Just (qsH, qsT) -> (psH, qsH) : zip psT qsT -- | 'zipWith' generalises 'zip' by zipping with the function given as -- the first argument, instead of a tupling function. For example, -- @'zipWith' (+)@ is applied to two ByteStrings to produce the list of -- corresponding sums. zipWith :: (Word8 -> Word8 -> a) -> ByteString -> ByteString -> [a] zipWith f ps qs = case uncons ps of Nothing -> [] Just (psH, psT) -> case uncons qs of Nothing -> [] Just (qsH, qsT) -> f psH qsH : zipWith f psT qsT {-# NOINLINE [1] zipWith #-} -- | A specialised version of `zipWith` for the common case of a -- simultaneous map over two ByteStrings, to build a 3rd. -- -- @since 0.11.1.0 packZipWith :: (Word8 -> Word8 -> Word8) -> ByteString -> ByteString -> ByteString packZipWith f (BS a l) (BS b m) = unsafeDupablePerformIO $ createFp len $ go a b where go p1 p2 = zipWith_ 0 where zipWith_ :: Int -> ForeignPtr Word8 -> IO () zipWith_ !n !r | n >= len = return () | otherwise = do x <- peekFpByteOff p1 n y <- peekFpByteOff p2 n pokeFpByteOff r n (f x y) zipWith_ (n+1) r len = min l m {-# INLINE packZipWith #-} {-# RULES "ByteString specialise zipWith" forall (f :: Word8 -> Word8 -> Word8) p q . zipWith f p q = unpack (packZipWith f p q) #-} -- | /O(n)/ 'unzip' transforms a list of pairs of bytes into a pair of -- ByteStrings. Note that this performs two 'pack' operations. unzip :: [(Word8,Word8)] -> (ByteString,ByteString) unzip ls = (pack (P.map fst ls), pack (P.map snd ls)) {-# INLINE unzip #-} -- --------------------------------------------------------------------- -- Special lists -- | /O(n)/ Returns all initial segments of the given 'ByteString', shortest first. inits :: ByteString -> [ByteString] -- see Note [Avoid NonEmpty combinators] inits bs = NE.toList $! initsNE bs -- | /O(n)/ Returns all initial segments of the given 'ByteString', shortest first. -- -- @since 0.11.4.0 initsNE :: ByteString -> NonEmpty ByteString -- see Note [Avoid NonEmpty combinators] initsNE (BS x len) = empty :| [BS x n | n <- [1..len]] -- | /O(n)/ Returns all final segments of the given 'ByteString', longest first. tails :: ByteString -> [ByteString] -- see Note [Avoid NonEmpty combinators] tails bs = NE.toList $! tailsNE bs -- | /O(n)/ Returns all final segments of the given 'ByteString', longest first. -- -- @since 0.11.4.0 tailsNE :: ByteString -> NonEmpty ByteString -- see Note [Avoid NonEmpty combinators] tailsNE p | null p = empty :| [] | otherwise = p :| tails (unsafeTail p) -- less efficent spacewise: tails (BS x l) = [BS (plusForeignPtr x n) (l-n) | n <- [0..l]] {- Note [Avoid NonEmpty combinators] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ As of base-4.17, most of the NonEmpty API is surprisingly lazy. Using it without forcing the arguments yourself is just begging GHC to make your code waste time allocating useless selector thunks. This may change in the future. See also this CLC issue: https://github.com/haskell/core-libraries-committee/issues/107 But until then, "refactor" with care! -} -- --------------------------------------------------------------------- -- ** Ordered 'ByteString's -- | /O(n)/ Sort a ByteString efficiently, using counting sort. sort :: ByteString -> ByteString sort (BS input l) -- qsort outperforms counting sort for small arrays | l <= 20 = unsafeCreateFp l $ \destFP -> do memcpyFp destFP input l unsafeWithForeignPtr destFP $ \dest -> c_sort dest (fromIntegral l) | otherwise = unsafeCreateFp l $ \p -> allocaArray 256 $ \arr -> do _ <- memset (castPtr arr) 0 (256 * fromIntegral (sizeOf (undefined :: CSize))) unsafeWithForeignPtr input (\x -> countOccurrences arr x l) let go 256 !_ = return () go i !ptr = do n <- peekElemOff arr i when (n /= 0) $ void $ memset ptr (fromIntegral i) n go (i + 1) (ptr `plusPtr` fromIntegral n) unsafeWithForeignPtr p (go 0) where -- Count the number of occurrences of each byte. -- Used by 'sort' countOccurrences :: Ptr CSize -> Ptr Word8 -> Int -> IO () countOccurrences !counts !str !len = go 0 where go !i | i == len = return () | otherwise = do k <- fromIntegral `fmap` peekElemOff str i x <- peekElemOff counts k pokeElemOff counts k (x + 1) go (i + 1) -- --------------------------------------------------------------------- -- Low level constructors -- | /O(n) construction/ Use a @ByteString@ with a function requiring a -- null-terminated @CString@. The @CString@ is a copy and will be freed -- automatically; it must not be stored or used after the -- subcomputation finishes. useAsCString :: ByteString -> (CString -> IO a) -> IO a useAsCString (BS fp l) action = allocaBytes (l+1) $ \buf -> do unsafeWithForeignPtr fp $ \p -> memcpy buf p l pokeByteOff buf l (0::Word8) action (castPtr buf) -- | /O(n) construction/ Use a @ByteString@ with a function requiring a @CStringLen@. -- As for @useAsCString@ this function makes a copy of the original @ByteString@. -- It must not be stored or used after the subcomputation finishes. useAsCStringLen :: ByteString -> (CStringLen -> IO a) -> IO a useAsCStringLen p@(BS _ l) f = useAsCString p $ \cstr -> f (cstr,l) ------------------------------------------------------------------------ -- | /O(n)./ Construct a new @ByteString@ from a @CString@. The -- resulting @ByteString@ is an immutable copy of the original -- @CString@, and is managed on the Haskell heap. The original -- @CString@ must be null terminated. packCString :: CString -> IO ByteString packCString cstr = do len <- c_strlen cstr packCStringLen (cstr, fromIntegral len) -- | /O(n)./ Construct a new @ByteString@ from a @CStringLen@. The -- resulting @ByteString@ is an immutable copy of the original @CStringLen@. -- The @ByteString@ is a normal Haskell value and will be managed on the -- Haskell heap. packCStringLen :: CStringLen -> IO ByteString packCStringLen (cstr, len) | len >= 0 = createFp len $ \fp -> unsafeWithForeignPtr fp $ \p -> memcpy p (castPtr cstr) len packCStringLen (_, len) = moduleErrorIO "packCStringLen" ("negative length: " ++ show len) ------------------------------------------------------------------------ -- | /O(n)/ Make a copy of the 'ByteString' with its own storage. -- This is mainly useful to allow the rest of the data pointed -- to by the 'ByteString' to be garbage collected, for example -- if a large string has been read in, and only a small part of it -- is needed in the rest of the program. -- copy :: ByteString -> ByteString copy (BS x l) = unsafeCreateFp l $ \p -> memcpyFp p x l -- --------------------------------------------------------------------- -- Line IO -- | Read a line from stdin. getLine :: IO ByteString getLine = hGetLine stdin -- | Read a line from a handle hGetLine :: Handle -> IO ByteString hGetLine h = wantReadableHandle_ "Data.ByteString.hGetLine" h $ \ h_@Handle__{haByteBuffer} -> do flushCharReadBuffer h_ buf <- readIORef haByteBuffer if isEmptyBuffer buf then fill h_ buf 0 [] else haveBuf h_ buf 0 [] where fill h_@Handle__{haByteBuffer,haDevice} buf !len xss = do (r,buf') <- Buffered.fillReadBuffer haDevice buf if r == 0 then do writeIORef haByteBuffer buf{ bufR=0, bufL=0 } if len > 0 then mkBigPS len xss else ioe_EOF else haveBuf h_ buf' len xss haveBuf h_@Handle__{haByteBuffer} buf@Buffer{ bufRaw=raw, bufR=w, bufL=r } len xss = do off <- findEOL r w raw let new_len = len + off - r xs <- mkPS raw r off -- if eol == True, then off is the offset of the '\n' -- otherwise off == w and the buffer is now empty. if off /= w then do if w == off + 1 then writeIORef haByteBuffer buf{ bufL=0, bufR=0 } else writeIORef haByteBuffer buf{ bufL = off + 1 } mkBigPS new_len (xs:xss) else fill h_ buf{ bufL=0, bufR=0 } new_len (xs:xss) -- find the end-of-line character, if there is one findEOL r w raw | r == w = return w | otherwise = do c <- readWord8Buf raw r if c == fromIntegral (ord '\n') then return r -- NB. not r+1: don't include the '\n' else findEOL (r+1) w raw mkPS :: RawBuffer Word8 -> Int -> Int -> IO ByteString mkPS buf start end = createFp len $ \fp -> memcpyFp fp (buf `plusForeignPtr` start) len where len = end - start mkBigPS :: Int -> [ByteString] -> IO ByteString mkBigPS _ [ps] = return ps mkBigPS _ pss = return $! concat (P.reverse pss) -- --------------------------------------------------------------------- -- Block IO -- | Outputs a 'ByteString' to the specified 'Handle'. hPut :: Handle -> ByteString -> IO () hPut _ (BS _ 0) = return () hPut h (BS ps l) = unsafeWithForeignPtr ps $ \p-> hPutBuf h p l -- | Similar to 'hPut' except that it will never block. Instead it returns -- any tail that did not get written. This tail may be 'empty' in the case that -- the whole string was written, or the whole original string if nothing was -- written. Partial writes are also possible. -- -- Note: on Windows and with Haskell implementation other than GHC, this -- function does not work correctly; it behaves identically to 'hPut'. -- hPutNonBlocking :: Handle -> ByteString -> IO ByteString hPutNonBlocking h bs@(BS ps l) = do bytesWritten <- unsafeWithForeignPtr ps $ \p-> hPutBufNonBlocking h p l return $! drop bytesWritten bs -- | A synonym for 'hPut', for compatibility hPutStr :: Handle -> ByteString -> IO () hPutStr = hPut -- | Write a ByteString to 'stdout'. putStr :: ByteString -> IO () putStr = hPut stdout ------------------------------------------------------------------------ -- Low level IO -- | Read a 'ByteString' directly from the specified 'Handle'. This -- is far more efficient than reading the characters into a 'String' -- and then using 'pack'. First argument is the Handle to read from, -- and the second is the number of bytes to read. It returns the bytes -- read, up to n, or 'empty' if EOF has been reached. -- -- 'hGet' is implemented in terms of 'hGetBuf'. -- -- If the handle is a pipe or socket, and the writing end -- is closed, 'hGet' will behave as if EOF was reached. -- hGet :: Handle -> Int -> IO ByteString hGet h i | i > 0 = createFpAndTrim i $ \fp -> unsafeWithForeignPtr fp $ \p -> hGetBuf h p i | i == 0 = return empty | otherwise = illegalBufferSize h "hGet" i -- | hGetNonBlocking is similar to 'hGet', except that it will never block -- waiting for data to become available, instead it returns only whatever data -- is available. If there is no data available to be read, 'hGetNonBlocking' -- returns 'empty'. -- -- Note: on Windows and with Haskell implementation other than GHC, this -- function does not work correctly; it behaves identically to 'hGet'. -- hGetNonBlocking :: Handle -> Int -> IO ByteString hGetNonBlocking h i | i > 0 = createFpAndTrim i $ \fp -> unsafeWithForeignPtr fp $ \p -> hGetBufNonBlocking h p i | i == 0 = return empty | otherwise = illegalBufferSize h "hGetNonBlocking" i -- | Like 'hGet', except that a shorter 'ByteString' may be returned -- if there are not enough bytes immediately available to satisfy the -- whole request. 'hGetSome' only blocks if there is no data -- available, and EOF has not yet been reached. -- hGetSome :: Handle -> Int -> IO ByteString hGetSome hh i | i > 0 = createFpAndTrim i $ \fp -> unsafeWithForeignPtr fp $ \p -> hGetBufSome hh p i | i == 0 = return empty | otherwise = illegalBufferSize hh "hGetSome" i illegalBufferSize :: Handle -> String -> Int -> IO a illegalBufferSize handle fn sz = ioError (mkIOError illegalOperationErrorType msg (Just handle) Nothing) --TODO: System.IO uses InvalidArgument here, but it's not exported :-( where msg = fn ++ ": illegal ByteString size " ++ showsPrec 9 sz [] -- | Read a handle's entire contents strictly into a 'ByteString'. -- -- This function reads chunks at a time, increasing the chunk size on each -- read. The final string is then reallocated to the appropriate size. For -- files > half of available memory, this may lead to memory exhaustion. -- Consider using 'readFile' in this case. -- -- The Handle is closed once the contents have been read, -- or if an exception is thrown. -- hGetContents :: Handle -> IO ByteString hGetContents hnd = do bs <- hGetContentsSizeHint hnd 1024 2048 `finally` hClose hnd -- don't waste too much space for small files: if length bs < 900 then return $! copy bs else return bs hGetContentsSizeHint :: Handle -> Int -- ^ first read size -> Int -- ^ initial buffer size increment -> IO ByteString hGetContentsSizeHint hnd = readChunks [] where readChunks chunks sz sz' = do fp <- mallocByteString sz readcount <- unsafeWithForeignPtr fp $ \buf -> hGetBuf hnd buf sz let chunk = BS fp readcount -- We rely on the hGetBuf behaviour (not hGetBufSome) where it reads up -- to the size we ask for, or EOF. So short reads indicate EOF. if readcount < sz && sz > 0 then return $! concat (P.reverse (chunk : chunks)) else readChunks (chunk : chunks) sz' ((sz+sz') `min` 32752) -- we grow the buffer sizes, but not too huge -- we concatenate in the end anyway -- | getContents. Read stdin strictly. Equivalent to hGetContents stdin -- The 'Handle' is closed after the contents have been read. -- getContents :: IO ByteString getContents = hGetContents stdin -- | The interact function takes a function of type @ByteString -> ByteString@ -- as its argument. The entire input from the standard input device is passed -- to this function as its argument, and the resulting string is output on the -- standard output device. -- interact :: (ByteString -> ByteString) -> IO () interact transformer = putStr . transformer =<< getContents -- | Read an entire file strictly into a 'ByteString'. -- readFile :: FilePath -> IO ByteString readFile f = withBinaryFile f ReadMode $ \h -> do -- hFileSize fails if file is not regular file (like -- /dev/null). Catch exception and try reading anyway. filesz <- catch (hFileSize h) useZeroIfNotRegularFile let readsz = (fromIntegral filesz `max` 0) + 1 hGetContentsSizeHint h readsz (readsz `max` 255) -- Our initial size is one bigger than the file size so that in the -- typical case we will read the whole file in one go and not have -- to allocate any more chunks. We'll still do the right thing if the -- file size is 0 or is changed before we do the read. where useZeroIfNotRegularFile :: IOException -> IO Integer useZeroIfNotRegularFile _ = return 0 modifyFile :: IOMode -> FilePath -> ByteString -> IO () modifyFile mode f txt = withBinaryFile f mode (`hPut` txt) -- | Write a 'ByteString' to a file. writeFile :: FilePath -> ByteString -> IO () writeFile = modifyFile WriteMode -- | Append a 'ByteString' to a file. appendFile :: FilePath -> ByteString -> IO () appendFile = modifyFile AppendMode -- --------------------------------------------------------------------- -- Internal utilities -- Common up near identical calls to `error' to reduce the number -- constant strings created when compiled: errorEmptyList :: HasCallStack => String -> a errorEmptyList fun = moduleError fun "empty ByteString" {-# NOINLINE errorEmptyList #-} moduleError :: HasCallStack => String -> String -> a moduleError fun msg = error (moduleErrorMsg fun msg) {-# NOINLINE moduleError #-} moduleErrorIO :: HasCallStack => String -> String -> IO a moduleErrorIO fun msg = throwIO . userError $ moduleErrorMsg fun msg {-# NOINLINE moduleErrorIO #-} moduleErrorMsg :: String -> String -> String moduleErrorMsg fun msg = "Data.ByteString." ++ fun ++ ':':' ':msg -- Find from the end of the string using predicate findFromEndUntil :: (Word8 -> Bool) -> ByteString -> Int findFromEndUntil f ps@(BS _ l) = case unsnoc ps of Nothing -> 0 Just (b, c) -> if f c then l else findFromEndUntil f b