X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=System%2FIO.hs;h=a7552f5626ee9afc44e8102ad9fff60e814fbff9;hb=43b264ae52debea04f4cd09aa5c5f5135b3a864a;hp=f94dca660ddb7ece8dc4e895aab61a9e141f9475;hpb=bca0cbb5e0ee7cf63a79721f7087abf02c866a5a;p=ghc-base.git

diff --git a/System/IO.hs b/System/IO.hs
index f94dca6..a7552f5 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),
 
@@ -57,9 +58,12 @@ module System.IO (
 
     -- * Operations on handles
 
-    -- ** Determining the size of a file
+    -- ** Determining and changing the size of a file
 
     hFileSize,		       -- :: Handle -> IO Integer
+#ifdef __GLASGOW_HASKELL__
+    hSetFileSize,              -- :: Handle -> Integer -> IO ()
+#endif
 
     -- ** Detecting the end of input
 
@@ -141,6 +145,7 @@ module System.IO (
 
     -- * Binary input and output
 
+    withBinaryFile,
     openBinaryFile,	       -- :: FilePath -> IOMode -> IO Handle
     hSetBinaryMode,	       -- :: Handle -> Bool -> IO ()
 #if !defined(__NHC__)
@@ -152,7 +157,12 @@ module System.IO (
     hGetBufNonBlocking,	       -- :: Handle -> Ptr a -> Int -> IO Int
 #endif
 
-    module System.IO.Error,
+    -- * Temporary files
+
+#ifdef __GLASGOW_HASKELL__
+    openTempFile,
+    openBinaryTempFile,
+#endif
   ) where
 
 #ifdef __GLASGOW_HASKELL__
@@ -160,7 +170,6 @@ 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
@@ -172,6 +181,7 @@ 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
 
@@ -207,6 +217,7 @@ import IO
   , hIsOpen, hIsClosed        -- :: Handle -> IO Bool
   , hIsReadable, hIsWritable  -- :: Handle -> IO Bool
   , hIsSeekable               -- :: Handle -> IO Bool
+  , bracket
 
   , IO ()
   , FilePath                  -- :: String
@@ -214,25 +225,6 @@ import IO
 import NHC.IOExtras (fixIO)
 #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
 
@@ -306,12 +298,9 @@ 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 = bracket (openFile f WriteMode) hClose
+			  (\hdl -> hPutStr hdl txt) 
 
 -- | The computation 'appendFile' @file str@ function appends the string @str@,
 -- to the file @file@.
@@ -323,10 +312,8 @@ 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 = bracket (openFile f AppendMode) hClose
+			   (\hdl -> hPutStr hdl txt)
 
 -- | The 'readLn' function combines 'getLine' and 'readIO'.
 
@@ -353,7 +340,7 @@ 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
@@ -371,14 +358,28 @@ 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
 
@@ -419,4 +420,25 @@ 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