{-# OPTIONS_GHC -cpp -fglasgow-exts -fno-warn-orphans -fno-warn-incomplete-patterns #-}
---
--- Module : ByteString.Lazy
+-- |
+-- Module : Data.ByteString.Lazy
-- Copyright : (c) Don Stewart 2006
-- (c) Duncan Coutts 2006
-- License : BSD-style
--
-- Maintainer : dons@cse.unsw.edu.au
-- Stability : experimental
--- Portability : portable, requires ffi and cpp
--- Tested with : GHC 6.4.1 and Hugs March 2005
+-- Portability : non-portable (instance of type synonym)
--
-
---
--- | A time and space-efficient implementation of lazy byte vectors
+-- A time and space-efficient implementation of lazy byte vectors
-- using lists of packed 'Word8' arrays, suitable for high performance
-- use, both in terms of large data quantities, or high speed
-- requirements. Byte vectors are encoded as lazy lists of strict 'Word8'
-- Some operations, such as concat, append, reverse and cons, have
-- better complexity than their "Data.ByteString" equivalents, due to
-- optimisations resulting from the list spine structure. And for other
--- operations Lazy ByteStrings are usually within a few percent of
+-- operations lazy ByteStrings are usually within a few percent of
-- strict ones, but with better heap usage. For data larger than the
-- available memory, or if you have tight memory constraints, this
-- module will be the only option. The default chunk size is 64k, which
--
-- > import qualified Data.ByteString.Lazy as B
--
--- Original GHC implementation by Bryan O\'Sullivan. Rewritten to use
--- UArray by Simon Marlow. Rewritten to support slices and use
--- ForeignPtr by David Roundy. Polished and extended by Don Stewart.
+-- Original GHC implementation by Bryan O\'Sullivan.
+-- Rewritten to use 'Data.Array.Unboxed.UArray' by Simon Marlow.
+-- Rewritten to support slices and use 'Foreign.ForeignPtr.ForeignPtr'
+-- by David Roundy.
+-- Polished and extended by Don Stewart.
-- Lazy variant by Duncan Coutts and Don Stewart.
--
-- You can however use 'repeat' and 'cycle' to build infinite lazy ByteStrings.
--
cons :: Word8 -> ByteString -> ByteString
-cons c (LPS (s:ss)) | P.length s <= 16 = LPS (P.cons c s : ss)
-cons c (LPS ss) = LPS (P.singleton c : ss)
+cons c (LPS (s:ss)) | P.length s < 16 = LPS (P.cons c s : ss)
+cons c (LPS ss) = LPS (P.singleton c : ss)
{-# INLINE cons #-}
-- | /O(n\/c)/ Append a byte to the end of a 'ByteString'
-- | /O(n\/c)/ 'take' @n@, applied to a ByteString @xs@, returns the prefix
-- of @xs@ of length @n@, or @xs@ itself if @n > 'length' xs@.
take :: Int64 -> ByteString -> ByteString
-take n _ | n < 0 = empty
-take i (LPS ps) = LPS (take' i ps)
- where take' _ [] = []
- take' 0 _ = []
+take i _ | i <= 0 = empty
+take i (LPS ps) = LPS (take' i ps)
+ where take' 0 _ = []
+ take' _ [] = []
take' n (x:xs) =
if n < fromIntegral (P.length x)
then P.take (fromIntegral n) x : []
drop :: Int64 -> ByteString -> ByteString
drop i p | i <= 0 = p
drop i (LPS ps) = LPS (drop' i ps)
- where drop' _ [] = []
- drop' 0 xs = xs
+ where drop' 0 xs = xs
+ drop' _ [] = []
drop' n (x:xs) =
if n < fromIntegral (P.length x)
then P.drop (fromIntegral n) x : xs
splitAt :: Int64 -> ByteString -> (ByteString, ByteString)
splitAt i p | i <= 0 = (empty, p)
splitAt i (LPS ps) = case splitAt' i ps of (a,b) -> (LPS a, LPS b)
- where splitAt' _ [] = ([], [])
- splitAt' 0 xs = ([], xs)
+ where splitAt' 0 xs = ([], xs)
+ splitAt' _ [] = ([], [])
splitAt' n (x:xs) =
if n < fromIntegral (P.length x)
then (P.take (fromIntegral n) x : [],
-- argument, consuming the delimiter. I.e.
--
-- > split '\n' "a\nb\nd\ne" == ["a","b","d","e"]
--- > split 'a' "aXaXaXa" == ["","X","X","X"]
+-- > split 'a' "aXaXaXa" == ["","X","X","X",""]
-- > split 'x' "x" == ["",""]
--
-- and