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|
-- Copyright (c) 2016-present, Facebook, Inc.
-- All rights reserved.
--
-- This source code is licensed under the BSD-style license found in
-- the LICENSE file in the root directory of this source tree. An
-- additional grant of patent rights can be found in the PATENTS file
-- in the same directory.
{-# LANGUAGE MultiWayIf #-}
-- |
-- Module : Codec.Compression.Zstd.Lazy
-- Copyright : (c) 2016-present, Facebook, Inc. All rights reserved.
--
-- License : BSD3
-- Maintainer : bryano@fb.com
-- Stability : experimental
-- Portability : GHC
--
-- Lazy compression and decompression support for zstd. Under the
-- hood, these are implemented using the streaming APIs.
module Codec.Compression.Zstd.Lazy
(
compress
, decompress
, S.maxCLevel
) where
import Data.ByteString.Lazy.Internal as L
import System.IO.Unsafe (unsafeInterleaveIO, unsafePerformIO)
import qualified Codec.Compression.Zstd.Streaming as S
import qualified Data.ByteString as B
import qualified Data.ByteString.Lazy as L
-- | Compress a payload. The input will be consumed lazily, and the
-- compressed result generated lazily.
--
-- /Note:/ if any error occurs, compression will fail part-way through
-- with a call to 'error'.
compress :: Int
-- ^ Compression level. Must be >= 1 and <= 'S.maxCLevel'.
-> ByteString
-- ^ Payload to compress. This will be consumed lazily.
-> ByteString
compress level bs = lazy (S.compress level) bs
-- | Decompress a payload. The input will be consumed lazily, and the
-- decompressed result generated lazily.
--
-- /Note:/ if any error occurs, decompression will fail part-way
-- through with a call to 'error'.
decompress :: ByteString -> ByteString
decompress bs = lazy S.decompress bs
lazy :: IO S.Result -> ByteString -> ByteString
lazy start b0 = unsafePerformIO (go b0 =<< start)
where
go _ (S.Error who what) = error (who ++ ": " ++ what)
go bs (S.Produce o k) = do
os <- unsafeInterleaveIO (go bs =<< k)
return (L.chunk o os)
go (Chunk c cs) (S.Consume f) = go cs =<< f c
go empty (S.Consume f) = go empty =<< f B.empty
go Empty (S.Done o) = return (chunk o Empty)
go input state = error $
"unpossible! " ++
show (L.length input) ++ " bytes of input left, " ++
show state ++ " stream state"
|
