X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=Data%2FTypeable.hs;h=7a8b7332267b549bd191f96a8725dacce5ea7671;hb=6b1a36a595eddf1e124529646afdb75c76a9966d;hp=f5b1c824ab08c39d56b4428415096ece6cd2df91;hpb=aaf764b3ad8b1816d68b5f27299eac125f08e1a5;p=haskell-directory.git

diff --git a/Data/Typeable.hs b/Data/Typeable.hs
index f5b1c82..7a8b733 100644
--- a/Data/Typeable.hs
+++ b/Data/Typeable.hs
@@ -1,4 +1,11 @@
-{-# OPTIONS_GHC -fno-implicit-prelude #-}
+{-# OPTIONS_GHC -fno-implicit-prelude -fallow-overlapping-instances #-}
+
+-- The -fallow-overlapping-instances flag allows the user to over-ride
+-- the instances for Typeable given here.  In particular, we provide an instance
+--	instance ... => Typeable (s a) 
+-- But a user might want to say
+--	instance ... => Typeable (MyType a b)
+
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Data.Typeable
@@ -18,15 +25,6 @@
 -- and type-safe cast (but not dynamics) to support the \"Scrap your
 -- boilerplate\" style of generic programming.
 --
--- Note, only relevant if you use dynamic linking. If you have a program
--- that is statically linked with Data.Typeable, and then dynamically link
--- a program that also uses Data.Typeable, you'll get two copies of the module.
--- That's fine, but behind the scenes, the module uses a mutable variable to
--- allocate unique Ids to type constructors.  So in the situation described,
--- there'll be two separate Id allocators, which aren't comparable to each other.
--- This can lead to chaos.  (It's a bug that we will fix.)  None of
--- this matters if you aren't using dynamic linking.
---
 -----------------------------------------------------------------------------
 
 module Data.Typeable
@@ -42,6 +40,7 @@ module Data.Typeable
 	-- * Type representations
 	TypeRep,	-- abstract, instance of: Eq, Show, Typeable
 	TyCon,		-- abstract, instance of: Eq, Show, Typeable
+	showsTypeRep,
 
 	-- * Construction of type representations
 	mkTyCon,	-- :: String  -> TyCon
@@ -55,6 +54,7 @@ module Data.Typeable
 	typeRepTyCon,	-- :: TypeRep -> TyCon
 	typeRepArgs,	-- :: TypeRep -> [TypeRep]
 	tyConString,	-- :: TyCon   -> String
+	typeRepKey,	-- :: TypeRep -> IO Int
 
 	-- * The other Typeable classes
 	-- | /Note:/ The general instances are provided for GHC only.
@@ -94,18 +94,36 @@ import GHC.Show
 import GHC.Err
 import GHC.Num
 import GHC.Float
-import GHC.Real( rem, Ratio )
-import GHC.IOBase
-import GHC.ST		-- So we can give Typeable instance for ST
-import GHC.Ptr          -- So we can give Typeable instance for Ptr
-import GHC.Stable       -- So we can give Typeable instance for StablePtr
+import GHC.Real		( rem, Ratio )
+import GHC.IOBase	(IORef,newIORef,unsafePerformIO)
+
+-- These imports are so we can define Typeable instances
+-- It'd be better to give Typeable instances in the modules themselves
+-- but they all have to be compiled before Typeable
+import GHC.IOBase	( IO, MVar, Exception, ArithException, IOException, 
+			  ArrayException, AsyncException, Handle )
+import GHC.ST		( ST )
+import GHC.STRef	( STRef )
+import GHC.Ptr          ( Ptr, FunPtr )
+import GHC.ForeignPtr   ( ForeignPtr )
+import GHC.Stable	( StablePtr, newStablePtr, freeStablePtr,
+			  deRefStablePtr, castStablePtrToPtr,
+			  castPtrToStablePtr )
+import GHC.Exception	( block )
+import GHC.Arr		( Array, STArray )
+
 #endif
 
 #ifdef __HUGS__
-import Hugs.Prelude
-import Hugs.IO
-import Hugs.IORef
-import Hugs.IOExts
+import Hugs.Prelude	( Key(..), TypeRep(..), TyCon(..), Ratio,
+			  Exception, ArithException, IOException,
+			  ArrayException, AsyncException, Handle,
+			  Ptr, FunPtr, ForeignPtr, StablePtr )
+import Hugs.IORef	( IORef, newIORef, readIORef, writeIORef )
+import Hugs.IOExts	( unsafePerformIO, unsafeCoerce )
+	-- For the Typeable instance
+import Hugs.Array	( Array )
+import Hugs.ConcBase	( MVar )
 #endif
 
 #ifdef __GLASGOW_HASKELL__
@@ -118,8 +136,9 @@ import NonStdUnsafeCoerce (unsafeCoerce)
 import NHC.IOExtras (IORef,newIORef,readIORef,writeIORef,unsafePerformIO)
 import IO (Handle)
 import Ratio (Ratio)
-import NHC.FFI (Ptr,StablePtr)
-#else
+	-- For the Typeable instance
+import NHC.FFI	( Ptr,FunPtr,StablePtr,ForeignPtr )
+import Array	( Array )
 #endif
 
 #include "Typeable.h"
@@ -146,9 +165,21 @@ data TyCon = TyCon !Key String
 
 instance Eq TyCon where
   (TyCon t1 _) == (TyCon t2 _) = t1 == t2
-
 #endif
 
+-- | Returns a unique integer associated with a 'TypeRep'.  This can
+-- be used for making a mapping ('Data.IntMap.IntMap') with TypeReps
+-- as the keys, for example.  It is guaranteed that @t1 == t2@ if and only if
+-- @typeRepKey t1 == typeRepKey t2@.
+--
+-- It is in the 'IO' monad because the actual value of the key may
+-- vary from run to run of the program.  You should only rely on
+-- the equality property, not any actual key value.  The relative ordering
+-- of keys has no meaning either.
+--
+typeRepKey :: TypeRep -> IO Int
+typeRepKey (TypeRep (Key i) _ _) = return i
+
 	-- 
 	-- let fTy = mkTyCon "Foo" in show (mkTyConApp (mkTyCon ",,")
 	--                                 [fTy,fTy,fTy])
@@ -250,6 +281,9 @@ instance Show TypeRep where
 	    showChar ' '      . 
 	    showArgs tys
 
+showsTypeRep :: TypeRep -> ShowS
+showsTypeRep = shows
+
 instance Show TyCon where
   showsPrec _ (TyCon _ s) = showString s
 
@@ -458,16 +492,37 @@ gcast2 x = r
 --
 -------------------------------------------------------------
 
+INSTANCE_TYPEABLE0((),unitTc,"()")
 INSTANCE_TYPEABLE1([],listTc,"[]")
 INSTANCE_TYPEABLE1(Maybe,maybeTc,"Maybe")
 INSTANCE_TYPEABLE1(Ratio,ratioTc,"Ratio")
 INSTANCE_TYPEABLE2(Either,eitherTc,"Either")
 INSTANCE_TYPEABLE2((->),funTc,"->")
 INSTANCE_TYPEABLE1(IO,ioTc,"IO")
+
+#if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
+-- Types defined in GHC.IOBase
+INSTANCE_TYPEABLE1(MVar,mvarTc,"MVar" )
+INSTANCE_TYPEABLE0(Exception,exceptionTc,"Exception")
+INSTANCE_TYPEABLE0(IOException,ioExceptionTc,"IOException")
+INSTANCE_TYPEABLE0(ArithException,arithExceptionTc,"ArithException")
+INSTANCE_TYPEABLE0(ArrayException,arrayExceptionTc,"ArrayException")
+INSTANCE_TYPEABLE0(AsyncException,asyncExceptionTc,"AsyncException")
+#endif
+
+-- Types defined in GHC.Arr
+INSTANCE_TYPEABLE2(Array,arrayTc,"Array")
+
 #ifdef __GLASGOW_HASKELL__
+-- Hugs has these too, but their Typeable<n> instances are defined
+-- elsewhere to keep this module within Haskell 98.
+-- This is important because every invocation of runhugs or ffihugs
+-- uses this module via Data.Dynamic.
 INSTANCE_TYPEABLE2(ST,stTc,"ST")
+INSTANCE_TYPEABLE2(STRef,stRefTc,"STRef")
+INSTANCE_TYPEABLE3(STArray,sTArrayTc,"STArray")
 #endif
-INSTANCE_TYPEABLE0((),unitTc,"()")
+
 #ifndef __NHC__
 INSTANCE_TYPEABLE2((,),pairTc,",")
 INSTANCE_TYPEABLE3((,,),tup3Tc,",,")
@@ -495,11 +550,13 @@ tup7Tc = mkTyCon ",,,,,,"
 
 instance Typeable7 (,,,,,,) where
   typeOf7 tu = mkTyConApp tup7Tc []
-
 #endif /* __NHC__ */
+
 INSTANCE_TYPEABLE1(Ptr,ptrTc,"Ptr")
-INSTANCE_TYPEABLE1(StablePtr,stableptrTc,"StablePtr")
-INSTANCE_TYPEABLE1(IORef,iorefTc,"IORef")
+INSTANCE_TYPEABLE1(FunPtr,funPtrTc,"FunPtr")
+INSTANCE_TYPEABLE1(ForeignPtr,foreignPtrTc,"ForeignPtr")
+INSTANCE_TYPEABLE1(StablePtr,stablePtrTc,"StablePtr")
+INSTANCE_TYPEABLE1(IORef,iORefTc,"IORef")
 
 -------------------------------------------------------
 --
@@ -512,6 +569,9 @@ INSTANCE_TYPEABLE0(Char,charTc,"Char")
 INSTANCE_TYPEABLE0(Float,floatTc,"Float")
 INSTANCE_TYPEABLE0(Double,doubleTc,"Double")
 INSTANCE_TYPEABLE0(Int,intTc,"Int")
+#ifndef __NHC__
+INSTANCE_TYPEABLE0(Word,wordTc,"Word" )
+#endif
 INSTANCE_TYPEABLE0(Integer,integerTc,"Integer")
 INSTANCE_TYPEABLE0(Ordering,orderingTc,"Ordering")
 INSTANCE_TYPEABLE0(Handle,handleTc,"Handle")
@@ -531,8 +591,6 @@ INSTANCE_TYPEABLE0(TypeRep,typeRepTc,"TypeRep")
 
 #ifdef __GLASGOW_HASKELL__
 INSTANCE_TYPEABLE0(RealWorld,realWorldTc,"RealWorld")
-INSTANCE_TYPEABLE0(Word,wordTc,"Word" )
-INSTANCE_TYPEABLE1(MVar,mvarTc,"MVar" )
 #endif
 
 ---------------------------------------------
@@ -550,19 +608,38 @@ data KeyPr = KeyPr !Key !Key deriving( Eq )
 hashKP :: KeyPr -> Int32
 hashKP (KeyPr (Key k1) (Key k2)) = (HT.hashInt k1 + HT.hashInt k2) `rem` HT.prime
 
-data Cache = Cache { next_key :: !(IORef Key),
+data Cache = Cache { next_key :: !(IORef Key),	-- Not used by GHC (calls genSym instead)
 		     tc_tbl   :: !(HT.HashTable String Key),
 		     ap_tbl   :: !(HT.HashTable KeyPr Key) }
 
 {-# NOINLINE cache #-}
+#ifdef __GLASGOW_HASKELL__
+foreign import ccall unsafe "RtsTypeable.h getOrSetTypeableStore"
+    getOrSetTypeableStore :: Ptr a -> IO (Ptr a)
+#endif
+
 cache :: Cache
 cache = unsafePerformIO $ do
 		empty_tc_tbl <- HT.new (==) HT.hashString
 		empty_ap_tbl <- HT.new (==) hashKP
 		key_loc      <- newIORef (Key 1) 
-		return (Cache { next_key = key_loc,
-				tc_tbl = empty_tc_tbl, 
-				ap_tbl = empty_ap_tbl })
+		let ret = Cache {	next_key = key_loc,
+					tc_tbl = empty_tc_tbl, 
+					ap_tbl = empty_ap_tbl }
+#ifdef __GLASGOW_HASKELL__
+		block $ do
+			stable_ref <- newStablePtr ret
+			let ref = castStablePtrToPtr stable_ref
+			ref2 <- getOrSetTypeableStore ref
+			if ref==ref2
+				then deRefStablePtr stable_ref
+				else do
+					freeStablePtr stable_ref
+					deRefStablePtr
+						(castPtrToStablePtr ref2)
+#else
+		return ret
+#endif
 
 newKey :: IORef Key -> IO Key
 #ifdef __GLASGOW_HASKELL__
@@ -574,16 +651,6 @@ newKey kloc = do { k@(Key i) <- readIORef kloc ;
 #endif
 
 #ifdef __GLASGOW_HASKELL__
--- In GHC we use the RTS's genSym function to get a new unique,
--- because in GHCi we might have two copies of the Data.Typeable
--- library running (one in the compiler and one in the running
--- program), and we need to make sure they don't share any keys.  
---
--- This is really a hack.  A better solution would be to centralise the
--- whole mutable state used by this module, i.e. both hashtables.  But
--- the current solution solves the immediate problem, which is that
--- dynamics generated in one world with one type were erroneously
--- being recognised by the other world as having a different type.
 foreign import ccall unsafe "genSymZh"
   genSym :: IO Int
 #endif