[project @ 2005-01-28 15:03:06 by simonmar]

[ghc-base.git] / System / Environment.hs

diff --git a/System/Environment.hs b/System/Environment.hs
index c20d7d7..3271e29 100644 (file)
--- a/System/Environment.hs
+++ b/System/Environment.hs
@@ -14,27 +14,47 @@
 
 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
+#ifdef __GLASGOW_HASKELL__
+      getEnvironment,
+#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
 #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 ->  
@@ -81,17 +101,19 @@ unpackProgName argv = do
 
    isPathSeparator :: Char -> Bool
    isPathSeparator '/'  = True
-#ifdef mingw32_TARGET_OS 
+#ifdef mingw32_HOST_OS 
    isPathSeparator '\\' = True
 #endif
    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 =
@@ -104,3 +126,70 @@ getEnv name =
 
 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 ()
+
+-- |'getEnvironment' retrieves the entire environment as a
+-- list of @(key,value)@ pairs.
+--
+-- If an environment entry does not contain an @\'=\'@ character,
+-- the @key@ is the whole entry and the @value@ is the empty string.
+
+getEnvironment :: IO [(String, String)]
+getEnvironment = do
+   pBlock <- getEnvBlock
+   if pBlock == nullPtr then return []
+    else do
+      stuff <- peekArray0 nullPtr pBlock >>= mapM peekCString
+      return (map divvy stuff)
+  where
+   divvy str = 
+      case break (=='=') str of
+        (xs,[])        -> (xs,[]) -- don't barf (like Posix.getEnvironment)
+        (name,_:value) -> (name,value)
+
+foreign import ccall unsafe "__hscore_environ" 
+  getEnvBlock :: IO (Ptr CString)
+#endif  /* __GLASGOW_HASKELL__ */