[project @ 2002-12-12 13:42:46 by ross]

[haskell-directory.git] / System / Environment.hs

diff --git a/System/Environment.hs b/System/Environment.hs
index c0fe1f9..fab7202 100644 (file)
--- a/System/Environment.hs
+++ b/System/Environment.hs
@@ -1,56 +1,80 @@
 -----------------------------------------------------------------------------
--- 
+-- |
 -- 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 1.2 2001/08/17 12:50:34 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
+#ifdef __GLASGOW_HASKELL__
+      withArgs,
+      withProgName,
+#endif
   ) where
 
 import Prelude
+import Control.Exception       ( bracket )
 
+#ifdef __GLASGOW_HASKELL__
 import Foreign
 import Foreign.C
-
-#ifdef __GLASGOW_HASKELL__
+import Control.Monad
 import GHC.IOBase
 #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
 -- line arguments (not including the program name).
 
+#ifdef __GLASGOW_HASKELL__
 getArgs :: IO [String]
 getArgs = 
   alloca $ \ p_argc ->  
   alloca $ \ p_argv -> do
    getProgArgv p_argc p_argv
-   p    <- peek p_argc
+   p    <- fromIntegral `liftM` peek p_argc
    argv <- peek p_argv
    peekArray (p - 1) (advancePtr argv 1) >>= mapM peekCString
+
    
-   
-foreign import "getProgArgv" getProgArgv :: Ptr Int -> Ptr (Ptr CString) -> IO ()
+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 ->
@@ -62,13 +86,23 @@ getProgName =
 unpackProgName :: Ptr (Ptr CChar) -> IO String   -- argv[0]
 unpackProgName argv = do 
   s <- peekElemOff argv 0 >>= peekCString
-  return (de_slash "" s)
+  return (basename s)
   where
-    -- re-start accumulating at every '/'
-    de_slash :: String -> String -> String
-    de_slash  acc []      = reverse acc
-    de_slash _acc ('/':xs) = de_slash []      xs
-    de_slash  acc (x:xs)   = de_slash (x:acc) xs
+   basename :: String -> String
+   basename f = go f f
+    where
+      go acc [] = acc
+      go acc (x:xs) 
+        | isPathSeparator x = go xs xs
+        | otherwise         = go acc xs
+
+   isPathSeparator :: Char -> Bool
+   isPathSeparator '/'  = True
+#ifdef mingw32_TARGET_OS 
+   isPathSeparator '\\' = True
+#endif
+   isPathSeparator _    = False
+
 
 -- Computation `getEnv var' returns the value
 -- of the environment variable {\em var}.  
@@ -85,5 +119,46 @@ 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 'System.getArgs'
+return @args@.
+-}
+withArgs xs act = do
+   p <- System.Environment.getProgName
+   withArgv (p:xs) act
+
+{-|
+@withProgName name act@ - while executing action @act@, have 'System.getProgName'return @name@.
+-}
+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 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__ */