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-----------------------------------------------------------------------------
-- |
-- Module : Network.StreamDebugger
-- Copyright : (c) Warrick Gray 2002, Bjorn Bringert 2003-2004, Simon Foster 2004, 2007 Robin Bate Boerop
-- License : BSD
--
-- Maintainer : Sigbjorn Finne <sigbjorn.finne@gmail.com>
-- Stability : experimental
-- Portability : non-portable (not tested)
--
-- Implements debugging of @Stream@s. Originally part of Gray's\/Bringert's
-- HTTP module.
--
-- * Changes by Robin Bate Boerop <robin@bateboerop.name>:
-- - Created. Made minor formatting changes.
--
-----------------------------------------------------------------------------
module Network.StreamDebugger
( StreamDebugger
, debugStream
, debugByteStream
) where
import Network.Stream (Stream(..))
import System.IO
( Handle, hFlush, hPutStrLn, IOMode(AppendMode), hClose, openFile,
hSetBuffering, BufferMode(NoBuffering)
)
import Network.TCP ( HandleStream, HStream,
StreamHooks(..), setStreamHooks, getStreamHooks )
-- | Allows stream logging. Refer to 'debugStream' below.
data StreamDebugger x
= Dbg Handle x
instance (Stream x) => Stream (StreamDebugger x) where
readBlock (Dbg h x) n =
do val <- readBlock x n
hPutStrLn h ("--readBlock " ++ show n)
hPutStrLn h (show val)
return val
readLine (Dbg h x) =
do val <- readLine x
hPutStrLn h ("--readLine")
hPutStrLn h (show val)
return val
writeBlock (Dbg h x) str =
do val <- writeBlock x str
hPutStrLn h ("--writeBlock" ++ show str)
hPutStrLn h (show val)
return val
close (Dbg h x) =
do hPutStrLn h "--closing..."
hFlush h
close x
hPutStrLn h "--closed."
hClose h
closeOnEnd (Dbg h x) f =
do hPutStrLn h ("--close-on-end.." ++ show f)
hFlush h
closeOnEnd x f
-- | Wraps a stream with logging I\/O.
-- The first argument is a filename which is opened in @AppendMode@.
debugStream :: (Stream a) => FilePath -> a -> IO (StreamDebugger a)
debugStream file stream =
do h <- openFile file AppendMode
hPutStrLn h ("File \"" ++ file ++ "\" opened for appending.")
return (Dbg h stream)
debugByteStream :: HStream ty => FilePath -> HandleStream ty -> IO (HandleStream ty)
debugByteStream file stream = do
sh <- getStreamHooks stream
case sh of
Just h
| hook_name h == file -> return stream -- reuse the stream hooks.
_ -> do
h <- openFile file AppendMode
hSetBuffering h NoBuffering
hPutStrLn h ("File \"" ++ file ++ "\" opened for appending.")
setStreamHooks stream (debugStreamHooks h file)
return stream
debugStreamHooks :: HStream ty => Handle -> String -> StreamHooks ty
debugStreamHooks h nm =
StreamHooks
{ hook_readBlock = \ toStr n val -> do
let eval = case val of { Left e -> Left e ; Right v -> Right $ toStr v}
hPutStrLn h ("--readBlock " ++ show n)
hPutStrLn h (either show show eval)
, hook_readLine = \ toStr val -> do
let eval = case val of { Left e -> Left e ; Right v -> Right $ toStr v}
hPutStrLn h ("--readLine")
hPutStrLn h (either show show eval)
, hook_writeBlock = \ toStr str val -> do
hPutStrLn h ("--writeBlock " ++ show val)
hPutStrLn h (toStr str)
, hook_close = do
hPutStrLn h "--closing..."
hFlush h
hClose h
, hook_name = nm
}
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