147 lines
5.2 KiB
Haskell
147 lines
5.2 KiB
Haskell
{-# LANGUAGE FlexibleContexts #-}
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-- |
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-- Module : Streamly.External.FileSystem.Handle
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-- Copyright : © 2020 Julian Ospald
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-- License : BSD3
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--
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-- Maintainer : Julian Ospald <hasufell@posteo.de>
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-- Stability : experimental
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-- Portability : portable
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--
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-- This module provides high-level file streaming API, working
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-- with file handles.
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module Streamly.External.FileSystem.Handle
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(
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-- * File reading
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readFileLBS
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, readFileLBS'
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, readFileStream
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, readFileStream'
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-- * File writing
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, copyFileHandle
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, copyFileHandle'
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, copyFileStream
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, copyFileStream'
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, copyLBS
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, copyLBS'
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)
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where
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import Control.Exception.Safe
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import Control.Monad.IO.Class ( liftIO )
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import Data.Word ( Word8 )
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import Prelude hiding ( readFile )
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import Streamly
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import Streamly.Memory.Array
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import System.IO ( Handle
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, hClose
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)
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import System.IO.Unsafe
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import qualified Data.ByteString.Lazy as L
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import qualified Data.ByteString.Lazy.Internal as BSLI
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import qualified Streamly.External.ByteString as Strict
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import qualified Streamly.External.ByteString.Lazy
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as Lazy
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import qualified Streamly.FileSystem.Handle as FH
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import qualified Streamly.Internal.Data.Unfold as SIU
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import qualified Streamly.Internal.Prelude as S
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-- https://github.com/psibi/streamly-bytestring/issues/7
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fromChunks :: SerialT IO (Array Word8) -> IO BSLI.ByteString
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fromChunks =
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S.foldrM (\x b -> unsafeInterleaveIO b >>= pure . BSLI.chunk x)
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(pure BSLI.Empty)
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. S.map Strict.fromArray
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-- |Read a file lazily as a lazy ByteString.
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--
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-- The handle is closed automatically, when the stream exits normally,
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-- aborts or gets garbage collected.
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--
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-- This uses `unsafeInterleaveIO` under the hood.
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readFileLBS :: Handle -- ^ readable file handle
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-> IO L.ByteString
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readFileLBS handle' = fromChunks (readFileStream handle')
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-- |Like 'readFileLBS', except doesn't close the handle..
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readFileLBS' :: Handle -- ^ readable file handle
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-> IO L.ByteString
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readFileLBS' handle' = fromChunks (readFileStream' handle')
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-- | Read a handle as a streamly filestream.
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--
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-- The handle is closed automatically, when the stream exits normally,
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-- aborts or gets garbage collected.
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-- The stream must not be used after the handle is closed.
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readFileStream :: (MonadCatch m, MonadAsync m)
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=> Handle
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-> SerialT m (Array Word8)
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readFileStream = S.unfold (SIU.finallyIO (liftIO . hClose) FH.readChunks)
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-- | Like 'readFileStream', except doesn't close the handle.
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readFileStream' :: (MonadCatch m, MonadAsync m)
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=> Handle
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-> SerialT m (Array Word8)
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readFileStream' = S.unfold FH.readChunks
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-- | Like 'copyFileStream', except for two file handles.
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--
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-- Both handles are closed automatically.
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copyFileHandle :: (MonadCatch m, MonadAsync m, MonadMask m)
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=> Handle -- ^ copy from this handle, must be readable
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-> Handle -- ^ copy to this handle, must be writable
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-> m ()
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copyFileHandle fromHandle toHandle =
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copyFileStream (readFileStream fromHandle) toHandle
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-- | Like 'copyFileHandle', except doesn't close the handles.
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copyFileHandle' :: (MonadCatch m, MonadAsync m, MonadMask m)
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=> Handle -- ^ copy from this handle, must be readable
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-> Handle -- ^ copy to this handle, must be writable
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-> m ()
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copyFileHandle' fromHandle toHandle =
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copyFileStream' (readFileStream' fromHandle) toHandle
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-- | Copy a stream to a file handle.
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--
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-- The handle is closed automatically after the stream is copied.
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copyFileStream :: (MonadCatch m, MonadAsync m, MonadMask m)
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=> SerialT m (Array Word8) -- ^ stream to copy
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-> Handle -- ^ file handle to copy to, must be writable
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-> m ()
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copyFileStream stream handle' =
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(flip finally) (liftIO $ hClose handle') $ copyFileStream' stream handle'
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-- | Like 'copyFileStream', except doesn't close the handle.
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copyFileStream' :: (MonadCatch m, MonadAsync m, MonadMask m)
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=> SerialT m (Array Word8) -- ^ stream to copy
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-> Handle -- ^ file handle to copy to, must be writable
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-> m ()
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copyFileStream' stream handle' = S.fold (FH.writeChunks handle') stream
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-- | Like 'copyFileStream', except with a lazy bytestring.
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--
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-- The handle is closed automatically after the bytestring is copied.
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copyLBS :: (MonadCatch m, MonadAsync m, MonadMask m)
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=> L.ByteString -- ^ lazy bytestring to copy
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-> Handle -- ^ file handle to copy to, must be writable
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-> m ()
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copyLBS lbs = copyFileStream (Lazy.toChunks lbs)
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-- | Like 'copyLBS', except doesn't close the handle.
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copyLBS' :: (MonadCatch m, MonadAsync m, MonadMask m)
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=> L.ByteString -- ^ lazy bytestring to copy
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-> Handle -- ^ file handle to copy to, must be writable
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-> m ()
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copyLBS' lbs = copyFileStream' (Lazy.toChunks lbs)
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