X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=System%2FIO.hs;h=0179d8df5e19c531593e35cb4be1e45c1a14b2f3;hb=4b26136ab82fb1ff12e49477c4833a9586d368c5;hp=729806f4ac7d6c237ea86a0d78fb3f2edbf3b2e8;hpb=7bce4ee1aa0287c9885647dfcf9de5072492a3fb;p=haskell-directory.git diff --git a/System/IO.hs b/System/IO.hs index 729806f..0179d8d 100644 --- a/System/IO.hs +++ b/System/IO.hs @@ -1,4 +1,4 @@ -{-# OPTIONS -fno-implicit-prelude #-} +{-# OPTIONS_GHC -fno-implicit-prelude #-} ----------------------------------------------------------------------------- -- | -- Module : System.IO @@ -36,6 +36,7 @@ module System.IO ( -- ** Opening files + withFile, openFile, -- :: FilePath -> IOMode -> IO Handle IOMode(ReadMode,WriteMode,AppendMode,ReadWriteMode), @@ -144,25 +145,22 @@ module System.IO ( -- * Binary input and output + withBinaryFile, openBinaryFile, -- :: FilePath -> IOMode -> IO Handle hSetBinaryMode, -- :: Handle -> Bool -> IO () -#if !defined(__NHC__) hPutBuf, -- :: Handle -> Ptr a -> Int -> IO () hGetBuf, -- :: Handle -> Ptr a -> Int -> IO Int -#endif #if !defined(__NHC__) && !defined(__HUGS__) hPutBufNonBlocking, -- :: Handle -> Ptr a -> Int -> IO Int hGetBufNonBlocking, -- :: Handle -> Ptr a -> Int -> IO Int #endif - -- * Temporary files + -- * Temporary files (not portable: GHC only) #ifdef __GLASGOW_HASKELL__ openTempFile, openBinaryTempFile, #endif - - module System.IO.Error, ) where #ifdef __GLASGOW_HASKELL__ @@ -170,7 +168,6 @@ import GHC.Base import GHC.IOBase -- Together these four Prelude modules define import GHC.Handle -- all the stuff exported by IO for the GHC version import GHC.IO -import GHC.ST ( fixST ) import GHC.Exception import GHC.Num import GHC.Read @@ -182,6 +179,7 @@ import Hugs.IO import Hugs.IOExts import Hugs.IORef import Hugs.Prelude ( throw, Exception(NonTermination) ) +import Control.Exception ( bracket ) import System.IO.Unsafe ( unsafeInterleaveIO ) #endif @@ -217,32 +215,15 @@ import IO , hIsOpen, hIsClosed -- :: Handle -> IO Bool , hIsReadable, hIsWritable -- :: Handle -> IO Bool , hIsSeekable -- :: Handle -> IO Bool + , bracket , IO () , FilePath -- :: String ) -import NHC.IOExtras (fixIO) +import NHC.IOExtras (fixIO, hPutBuf, hGetBuf) +import NHC.FFI (Ptr) #endif -import System.IO.Error ( - isAlreadyExistsError, isDoesNotExistError, -- :: IOError -> Bool - isAlreadyInUseError, isFullError, - isEOFError, isIllegalOperation, - isPermissionError, isUserError, - - ioeGetErrorString, -- :: IOError -> String - ioeGetHandle, -- :: IOError -> Maybe Handle - ioeGetFileName, -- :: IOError -> Maybe FilePath - - try, -- :: IO a -> IO (Either IOError a) - - -- re-exports of Prelude names - IOError, - ioError, -- :: IOError -> IO a - userError, -- :: String -> IOError - catch -- :: IO a -> (IOError -> IO a) -> IO a - ) - -- ----------------------------------------------------------------------------- -- Standard IO @@ -316,12 +297,8 @@ readFile name = openFile name ReadMode >>= hGetContents -- | The computation 'writeFile' @file str@ function writes the string @str@, -- to the file @file@. - -writeFile :: FilePath -> String -> IO () -writeFile name str = do - hdl <- openFile name WriteMode - hPutStr hdl str - hClose hdl +writeFile :: FilePath -> String -> IO () +writeFile f txt = withFile f WriteMode (\ hdl -> hPutStr hdl txt) -- | The computation 'appendFile' @file str@ function appends the string @str@, -- to the file @file@. @@ -333,10 +310,7 @@ writeFile name str = do -- > main = appendFile "squares" (show [(x,x*x) | x <- [0,0.1..2]]) appendFile :: FilePath -> String -> IO () -appendFile name str = do - hdl <- openFile name AppendMode - hPutStr hdl str - hClose hdl +appendFile f txt = withFile f AppendMode (\ hdl -> hPutStr hdl txt) -- | The 'readLn' function combines 'getLine' and 'readIO'. @@ -363,7 +337,7 @@ readIO s = case (do { (x,t) <- reads s ; -- -- This operation may fail with: -- --- * 'isEOFError' if the end of file has been reached. +-- * 'System.IO.Error.isEOFError' if the end of file has been reached. hReady :: Handle -> IO Bool hReady h = hWaitForInput h 0 @@ -381,14 +355,28 @@ hPutStrLn hndl str = do -- -- This operation may fail with: -- --- * 'isFullError' if the device is full; or +-- * 'System.IO.Error.isFullError' if the device is full; or -- --- * 'isPermissionError' if another system resource limit would be exceeded. +-- * 'System.IO.Error.isPermissionError' if another system resource limit would be exceeded. hPrint :: Show a => Handle -> a -> IO () hPrint hdl = hPutStrLn hdl . show #endif /* !__NHC__ */ +-- | @'withFile' name mode act@ opens a file using 'openFile' and passes +-- the resulting handle to the computation @act@. The handle will be +-- closed on exit from 'withFile', whether by normal termination or by +-- raising an exception. +withFile :: FilePath -> IOMode -> (Handle -> IO r) -> IO r +withFile name mode = bracket (openFile name mode) hClose + +-- | @'withBinaryFile' name mode act@ opens a file using 'openBinaryFile' +-- and passes the resulting handle to the computation @act@. The handle +-- will be closed on exit from 'withBinaryFile', whether by normal +-- termination or by raising an exception. +withBinaryFile :: FilePath -> IOMode -> (Handle -> IO r) -> IO r +withBinaryFile name mode = bracket (openBinaryFile name mode) hClose + -- --------------------------------------------------------------------------- -- fixIO @@ -429,4 +417,25 @@ hSetBinaryMode _ _ = return () -- the file until the entire contents of the file have been consumed. -- It follows that an attempt to write to a file (using 'writeFile', for -- example) that was earlier opened by 'readFile' will usually result in --- failure with 'isAlreadyInUseError'. +-- failure with 'System.IO.Error.isAlreadyInUseError'. + +-- ----------------------------------------------------------------------------- +-- Utils + +#ifdef __GLASGOW_HASKELL__ +-- Copied here to avoid recursive dependency with Control.Exception +bracket + :: IO a -- ^ computation to run first (\"acquire resource\") + -> (a -> IO b) -- ^ computation to run last (\"release resource\") + -> (a -> IO c) -- ^ computation to run in-between + -> IO c -- returns the value from the in-between computation +bracket before after thing = + block (do + a <- before + r <- catchException + (unblock (thing a)) + (\e -> do { after a; throw e }) + after a + return r + ) +#endif