Use explicit language extensions & remove extension fields from base.cabal

[ghc-base.git] / Foreign / C / String.hs

diff --git a/Foreign/C/String.hs b/Foreign/C/String.hs
index df82aff..becfa4e 100644 (file)
--- a/Foreign/C/String.hs
+++ b/Foreign/C/String.hs
@@ -1,4 +1,5 @@
-{-# OPTIONS_GHC -fno-implicit-prelude #-}
+{-# LANGUAGE CPP, NoImplicitPrelude #-}
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Foreign.C.String
@@ -59,6 +60,11 @@ module Foreign.C.String (   -- representation of strings in C
   castCharToCChar,   -- :: Char -> CChar
   castCCharToChar,   -- :: CChar -> Char
 
+  castCharToCUChar,  -- :: Char -> CUChar
+  castCUCharToChar,  -- :: CUChar -> Char
+  castCharToCSChar,  -- :: Char -> CSChar
+  castCSCharToChar,  -- :: CSChar -> Char
+
   peekCAString,      -- :: CString    -> IO String
   peekCAStringLen,   -- :: CStringLen -> IO String
   newCAString,       -- :: String -> IO CString
@@ -99,7 +105,6 @@ import Data.Word
 import GHC.List
 import GHC.Real
 import GHC.Num
-import GHC.IOBase
 import GHC.Base
 #else
 import Data.Char ( chr, ord )
@@ -200,6 +205,26 @@ castCCharToChar ch = unsafeChr (fromIntegral (fromIntegral ch :: Word8))
 castCharToCChar :: Char -> CChar
 castCharToCChar ch = fromIntegral (ord ch)
 
+-- | Convert a C @unsigned char@, representing a Latin-1 character, to
+-- the corresponding Haskell character.
+castCUCharToChar :: CUChar -> Char
+castCUCharToChar ch = unsafeChr (fromIntegral (fromIntegral ch :: Word8))
+
+-- | Convert a Haskell character to a C @unsigned char@.
+-- This function is only safe on the first 256 characters.
+castCharToCUChar :: Char -> CUChar
+castCharToCUChar ch = fromIntegral (ord ch)
+
+-- | Convert a C @signed char@, representing a Latin-1 character, to the
+-- corresponding Haskell character.
+castCSCharToChar :: CSChar -> Char
+castCSCharToChar ch = unsafeChr (fromIntegral (fromIntegral ch :: Word8))
+
+-- | Convert a Haskell character to a C @signed char@.
+-- This function is only safe on the first 256 characters.
+castCharToCSChar :: Char -> CSChar
+castCharToCSChar ch = fromIntegral (ord ch)
+
 -- | Marshal a NUL terminated C string into a Haskell string.
 --
 peekCAString    :: CString -> IO String
@@ -269,9 +294,7 @@ newCAString str = do
 --
 newCAStringLen     :: String -> IO CStringLen
 #ifndef __GLASGOW_HASKELL__
-newCAStringLen str  = do
-  a <- newArray (charsToCChars str)
-  return (pairLength str a)
+newCAStringLen str  = newArrayLen (charsToCChars str)
 #else
 newCAStringLen str = do
   ptr <- mallocArray0 len
@@ -315,10 +338,10 @@ withCAString str f =
 --   storage must /not/ be used after this.
 --
 withCAStringLen         :: String -> (CStringLen -> IO a) -> IO a
+withCAStringLen str f    =
 #ifndef __GLASGOW_HASKELL__
-withCAStringLen str act  = withArray (charsToCChars str) $ act . pairLength str
+  withArrayLen (charsToCChars str) $ \ len ptr -> f (ptr, len)
 #else
-withCAStringLen str f =
   allocaArray len $ \ptr ->
       let
         go [] n     = n `seq` return () -- make it strict in n
@@ -338,10 +361,11 @@ withCAStringLen str f =
 nUL :: CChar
 nUL  = 0
 
--- pair a C string with the length of the given Haskell string
---
-pairLength :: String -> a -> (a, Int)
-pairLength  = flip (,) . length
+-- allocate an array to hold the list and pair it with the number of elements
+newArrayLen        :: Storable a => [a] -> IO (Ptr a, Int)
+newArrayLen xs      = do
+  a <- newArray xs
+  return (a, length xs)
 
 #ifndef __GLASGOW_HASKELL__
 -- cast [CChar] to [Char]
@@ -403,9 +427,7 @@ newCWString  = newArray0 wNUL . charsToCWchars
 --   'Foreign.Marshal.Alloc.finalizerFree'.
 --
 newCWStringLen     :: String -> IO CWStringLen
-newCWStringLen str  = do
-  a <- newArray (charsToCWchars str)
-  return (pairLength str a)
+newCWStringLen str  = newArrayLen (charsToCWchars str)
 
 -- | Marshal a Haskell string into a NUL terminated C wide string using
 -- temporary storage.
@@ -429,7 +451,8 @@ withCWString  = withArray0 wNUL . charsToCWchars
 --   storage must /not/ be used after this.
 --
 withCWStringLen         :: String -> (CWStringLen -> IO a) -> IO a
-withCWStringLen str act  = withArray (charsToCWchars str) $ act . pairLength str
+withCWStringLen str f    =
+  withArrayLen (charsToCWchars str) $ \ len ptr -> f (ptr, len)
 
 -- auxiliary definitions
 -- ----------------------