add WordPtr and IntPtr types to Foreign.Ptr, with associated conversions

As suggested by John Meacham.  

I had to move the Show instance for Ptr into GHC.ForeignPtr to avoid
recursive dependencies.

1 files changed, 22 insertions, 4 deletions

diff --git a/libraries/base/GHC/ForeignPtr.hs b/libraries/base/GHC/ForeignPtr.hs
index c9217ef836..4c8113653c 100644
--- a/libraries/base/GHC/ForeignPtr.hs
+++ b/libraries/base/GHC/ForeignPtr.hs
@@ -31,16 +31,17 @@ module GHC.ForeignPtr
   ) where
 
 import Control.Monad 	( sequence_ )
-import Foreign.Ptr
 import Foreign.Storable
+import Numeric		( showHex )
 
-import GHC.List  	( null )
+import GHC.Show
+import GHC.Num
+import GHC.List  	( null, replicate, length )
 import GHC.Base
 import GHC.IOBase
 import GHC.STRef	( STRef(..) )
-import GHC.Ptr		( Ptr(..) )
+import GHC.Ptr		( Ptr(..), FunPtr, castFunPtrToPtr )
 import GHC.Err
-import GHC.Show
 
 -- |The type 'ForeignPtr' represents references to objects that are
 -- maintained in a foreign language, i.e., that are not part of the
@@ -82,6 +83,23 @@ instance Ord (ForeignPtr a) where
 instance Show (ForeignPtr a) where
     showsPrec p f = showsPrec p (unsafeForeignPtrToPtr f)
 
+#include "MachDeps.h"
+
+#if (WORD_SIZE_IN_BITS == 32 || WORD_SIZE_IN_BITS == 64)
+instance Show (Ptr a) where
+   showsPrec p (Ptr a) rs = pad_out (showHex (word2Integer(int2Word#(addr2Int# a))) "") rs
+     where
+        -- want 0s prefixed to pad it out to a fixed length.
+       pad_out ls rs = 
+	  '0':'x':(replicate (2*SIZEOF_HSPTR - length ls) '0') ++ ls ++ rs
+       -- word2Integer :: Word# -> Integer (stolen from Word.lhs)
+       word2Integer w = case word2Integer# w of
+			(# s, d #) -> J# s d
+
+instance Show (FunPtr a) where
+   showsPrec p = showsPrec p . castFunPtrToPtr
+#endif
+
 -- |A Finalizer is represented as a pointer to a foreign function that, at
 -- finalisation time, gets as an argument a plain pointer variant of the
 -- foreign pointer that the finalizer is associated with.