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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 : bjorn@bringert.net
-- 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
) where
import Network.Stream (Stream(..))
import System.IO
( Handle, hFlush, hPutStrLn, IOMode(AppendMode), hClose, openFile
)
-- | 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 ++ ' ' : show val)
return val
readLine (Dbg h x) =
do val <- readLine x
hPutStrLn h ("readLine " ++ show val)
return val
writeBlock (Dbg h x) str =
do val <- writeBlock x str
hPutStrLn h ("writeBlock " ++ show val ++ ' ' : show str)
return val
close (Dbg h x) =
do hPutStrLn h "closing..."
hFlush h
close x
hPutStrLn h "...closed"
hClose h
-- | 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)
|
