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Diffstat (limited to 'haddock-library/vendor/attoparsec-0.13.1.0/Data/Attoparsec/ByteString/Buffer.hs')
| -rw-r--r-- | haddock-library/vendor/attoparsec-0.13.1.0/Data/Attoparsec/ByteString/Buffer.hs | 156 |
1 files changed, 0 insertions, 156 deletions
diff --git a/haddock-library/vendor/attoparsec-0.13.1.0/Data/Attoparsec/ByteString/Buffer.hs b/haddock-library/vendor/attoparsec-0.13.1.0/Data/Attoparsec/ByteString/Buffer.hs deleted file mode 100644 index ac94dfcc..00000000 --- a/haddock-library/vendor/attoparsec-0.13.1.0/Data/Attoparsec/ByteString/Buffer.hs +++ /dev/null @@ -1,156 +0,0 @@ -{-# LANGUAGE BangPatterns #-} --- | --- Module : Data.Attoparsec.ByteString.Buffer --- Copyright : Bryan O'Sullivan 2007-2015 --- License : BSD3 --- --- Maintainer : bos@serpentine.com --- Stability : experimental --- Portability : GHC --- --- An "immutable" buffer that supports cheap appends. --- --- A Buffer is divided into an immutable read-only zone, followed by a --- mutable area that we've preallocated, but not yet written to. --- --- We overallocate at the end of a Buffer so that we can cheaply --- append. Since a user of an existing Buffer cannot see past the end --- of its immutable zone into the data that will change during an --- append, this is safe. --- --- Once we run out of space at the end of a Buffer, we do the usual --- doubling of the buffer size. --- --- The fact of having a mutable buffer really helps with performance, --- but it does have a consequence: if someone misuses the Partial API --- that attoparsec uses by calling the same continuation repeatedly --- (which never makes sense in practice), they could overwrite data. --- --- Since the API *looks* pure, it should *act* pure, too, so we use --- two generation counters (one mutable, one immutable) to track the --- number of appends to a mutable buffer. If the counters ever get out --- of sync, someone is appending twice to a mutable buffer, so we --- duplicate the entire buffer in order to preserve the immutability --- of its older self. --- --- While we could go a step further and gain protection against API --- abuse on a multicore system, by use of an atomic increment --- instruction to bump the mutable generation counter, that would be --- very expensive, and feels like it would also be in the realm of the --- ridiculous. Clients should never call a continuation more than --- once; we lack a linear type system that could enforce this; and --- there's only so far we should go to accommodate broken uses. - -module Data.Attoparsec.ByteString.Buffer - ( - Buffer - , buffer - , unbuffer - , pappend - , length - , unsafeIndex - , substring - , unsafeDrop - ) where - -import Control.Exception (assert) -import Data.ByteString.Internal (ByteString(..), memcpy, nullForeignPtr) -import Data.Attoparsec.Internal.Fhthagn (inlinePerformIO) -import Data.List (foldl1') -import Data.Monoid as Mon (Monoid(..)) -import Data.Semigroup (Semigroup(..)) -import Data.Word (Word8) -import Foreign.ForeignPtr (ForeignPtr, withForeignPtr) -import Foreign.Ptr (castPtr, plusPtr) -import Foreign.Storable (peek, peekByteOff, poke, sizeOf) -import GHC.ForeignPtr (mallocPlainForeignPtrBytes) -import Prelude hiding (length) - --- If _cap is zero, this buffer is empty. -data Buffer = Buf { - _fp :: {-# UNPACK #-} !(ForeignPtr Word8) - , _off :: {-# UNPACK #-} !Int - , _len :: {-# UNPACK #-} !Int - , _cap :: {-# UNPACK #-} !Int - , _gen :: {-# UNPACK #-} !Int - } - -instance Show Buffer where - showsPrec p = showsPrec p . unbuffer - --- | The initial 'Buffer' has no mutable zone, so we can avoid all --- copies in the (hopefully) common case of no further input being fed --- to us. -buffer :: ByteString -> Buffer -buffer (PS fp off len) = Buf fp off len len 0 - -unbuffer :: Buffer -> ByteString -unbuffer (Buf fp off len _ _) = PS fp off len - -instance Semigroup Buffer where - (Buf _ _ _ 0 _) <> b = b - a <> (Buf _ _ _ 0 _) = a - buf <> (Buf fp off len _ _) = append buf fp off len - -instance Monoid Buffer where - mempty = Buf nullForeignPtr 0 0 0 0 - - mappend = (<>) - - mconcat [] = Mon.mempty - mconcat xs = foldl1' mappend xs - -pappend :: Buffer -> ByteString -> Buffer -pappend (Buf _ _ _ 0 _) bs = buffer bs -pappend buf (PS fp off len) = append buf fp off len - -append :: Buffer -> ForeignPtr a -> Int -> Int -> Buffer -append (Buf fp0 off0 len0 cap0 gen0) !fp1 !off1 !len1 = - inlinePerformIO . withForeignPtr fp0 $ \ptr0 -> - withForeignPtr fp1 $ \ptr1 -> do - let genSize = sizeOf (0::Int) - newlen = len0 + len1 - gen <- if gen0 == 0 - then return 0 - else peek (castPtr ptr0) - if gen == gen0 && newlen <= cap0 - then do - let newgen = gen + 1 - poke (castPtr ptr0) newgen - memcpy (ptr0 `plusPtr` (off0+len0)) - (ptr1 `plusPtr` off1) - (fromIntegral len1) - return (Buf fp0 off0 newlen cap0 newgen) - else do - let newcap = newlen * 2 - fp <- mallocPlainForeignPtrBytes (newcap + genSize) - withForeignPtr fp $ \ptr_ -> do - let ptr = ptr_ `plusPtr` genSize - newgen = 1 - poke (castPtr ptr_) newgen - memcpy ptr (ptr0 `plusPtr` off0) (fromIntegral len0) - memcpy (ptr `plusPtr` len0) (ptr1 `plusPtr` off1) - (fromIntegral len1) - return (Buf fp genSize newlen newcap newgen) - -length :: Buffer -> Int -length (Buf _ _ len _ _) = len -{-# INLINE length #-} - -unsafeIndex :: Buffer -> Int -> Word8 -unsafeIndex (Buf fp off len _ _) i = assert (i >= 0 && i < len) . - inlinePerformIO . withForeignPtr fp $ flip peekByteOff (off+i) -{-# INLINE unsafeIndex #-} - -substring :: Int -> Int -> Buffer -> ByteString -substring s l (Buf fp off len _ _) = - assert (s >= 0 && s <= len) . - assert (l >= 0 && l <= len-s) $ - PS fp (off+s) l -{-# INLINE substring #-} - -unsafeDrop :: Int -> Buffer -> ByteString -unsafeDrop s (Buf fp off len _ _) = - assert (s >= 0 && s <= len) $ - PS fp (off+s) (len-s) -{-# INLINE unsafeDrop #-} |