X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=System%2FEnvironment.hs;h=245a9db41900c5a1b488189e7cdd1a2860118323;hb=deab48c5498f00001e37273a02471bbdd7696e6b;hp=d85a52dd2d1ae61a87c387b336d8ca625bebef1c;hpb=1e1907fb42b74de4feb5ac8af10846db31e56edb;p=ghc-base.git

diff --git a/System/Environment.hs b/System/Environment.hs
index d85a52d..245a9db 100644
--- a/System/Environment.hs
+++ b/System/Environment.hs
@@ -1,42 +1,58 @@
 -----------------------------------------------------------------------------
--- 
+-- |
 -- Module      :  System.Environment
 -- Copyright   :  (c) The University of Glasgow 2001
--- License     :  BSD-style (see the file libraries/core/LICENSE)
+-- License     :  BSD-style (see the file libraries/base/LICENSE)
 -- 
 -- Maintainer  :  libraries@haskell.org
 -- Stability   :  provisional
 -- Portability :  portable
 --
--- $Id: Environment.hs,v 1.4 2002/01/02 14:40:11 simonmar Exp $
---
 -- Miscellaneous information about the system environment.
 --
 -----------------------------------------------------------------------------
 
 module System.Environment
     ( 
-    , getArgs	    -- :: IO [String]
-    , getProgName   -- :: IO String
-    , getEnv        -- :: String -> IO String
+      getArgs,	     -- :: IO [String]
+      getProgName,   -- :: IO String
+      getEnv,        -- :: String -> IO String
+#ifndef __NHC__
+      withArgs,
+      withProgName,
+#endif
   ) where
 
 import Prelude
 
+#ifdef __GLASGOW_HASKELL__
 import Foreign
 import Foreign.C
+import Control.Exception 	( bracket )
 import Control.Monad
-
-#ifdef __GLASGOW_HASKELL__
 import GHC.IOBase
+#include "config.h"
+#endif
+
+#ifdef __HUGS__
+import Hugs.System
+#endif
+
+#ifdef __NHC__
+import System
+  ( getArgs
+  , getProgName
+  , getEnv
+  )
 #endif
 
 -- ---------------------------------------------------------------------------
 -- getArgs, getProgName, getEnv
 
--- Computation `getArgs' returns a list of the program's command
+-- | Computation 'getArgs' returns a list of the program's command
 -- line arguments (not including the program name).
 
+#ifdef __GLASGOW_HASKELL__
 getArgs :: IO [String]
 getArgs = 
   alloca $ \ p_argc ->  
@@ -47,12 +63,19 @@ getArgs =
    peekArray (p - 1) (advancePtr argv 1) >>= mapM peekCString
 
    
-foreign import "getProgArgv" unsafe 
+foreign import ccall unsafe "getProgArgv"
   getProgArgv :: Ptr CInt -> Ptr (Ptr CString) -> IO ()
 
--- Computation `getProgName' returns the name of the program
--- as it was invoked.
+{-|
+Computation 'getProgName' returns the name of the program as it was
+invoked.
 
+However, this is hard-to-impossible to implement on some non-Unix
+OSes, so instead, for maximum portability, we just return the leafname
+of the program as invoked. Even then there are some differences
+between platforms: on Windows, for example, a program invoked as foo
+is probably really @FOO.EXE@, and that is what 'getProgName' will return.
+-}
 getProgName :: IO String
 getProgName = 
   alloca $ \ p_argc ->
@@ -82,11 +105,13 @@ unpackProgName argv = do
    isPathSeparator _    = False
 
 
--- Computation `getEnv var' returns the value
--- of the environment variable {\em var}.  
-
--- This computation may fail with
---    NoSuchThing: The environment variable does not exist.
+-- | Computation 'getEnv' @var@ returns the value
+-- of the environment variable @var@.  
+--
+-- This computation may fail with:
+--
+--  * 'System.IO.Error.isDoesNotExistError' if the environment variable
+--    does not exist.
 
 getEnv :: String -> IO String
 getEnv name =
@@ -97,5 +122,50 @@ getEnv name =
         else ioException (IOError Nothing NoSuchThing "getEnv"
 			  "no environment variable" (Just name))
 
-foreign import ccall "getenv" unsafe 
+foreign import ccall unsafe "getenv"
    c_getenv :: CString -> IO (Ptr CChar)
+
+{-|
+'withArgs' @args act@ - while executing action @act@, have 'getArgs'
+return @args@.
+-}
+withArgs :: [String] -> IO a -> IO a
+withArgs xs act = do
+   p <- System.Environment.getProgName
+   withArgv (p:xs) act
+
+{-|
+'withProgName' @name act@ - while executing action @act@,
+have 'getProgName' return @name@.
+-}
+withProgName :: String -> IO a -> IO a
+withProgName nm act = do
+   xs <- System.Environment.getArgs
+   withArgv (nm:xs) act
+
+-- Worker routine which marshals and replaces an argv vector for
+-- the duration of an action.
+
+withArgv :: [String] -> IO a -> IO a
+withArgv new_args act = do
+  pName <- System.Environment.getProgName
+  existing_args <- System.Environment.getArgs
+  bracket (setArgs new_args) 
+	  (\argv -> do setArgs (pName:existing_args); freeArgv argv)
+  	  (const act)
+
+freeArgv :: Ptr CString -> IO ()
+freeArgv argv = do
+  size <- lengthArray0 nullPtr argv
+  sequence_ [peek (argv `advancePtr` i) >>= free | i <- [size, size-1 .. 0]]
+  free argv
+
+setArgs :: [String] -> IO (Ptr CString)
+setArgs argv = do
+  vs <- mapM newCString argv >>= newArray0 nullPtr
+  setArgsPrim (length argv) vs
+  return vs
+
+foreign import ccall unsafe "setProgArgv" 
+  setArgsPrim  :: Int -> Ptr CString -> IO ()
+#endif  /* __GLASGOW_HASKELL__ */