Put some explicit import lists in Data.Typeable
[ghc.git] / libraries / base / Data / Typeable.hs
1 {-# OPTIONS_GHC -XNoImplicitPrelude -XOverlappingInstances -funbox-strict-fields #-}
2
3 -- The -XOverlappingInstances flag allows the user to over-ride
4 -- the instances for Typeable given here. In particular, we provide an instance
5 -- instance ... => Typeable (s a)
6 -- But a user might want to say
7 -- instance ... => Typeable (MyType a b)
8
9 -----------------------------------------------------------------------------
10 -- |
11 -- Module : Data.Typeable
12 -- Copyright : (c) The University of Glasgow, CWI 2001--2004
13 -- License : BSD-style (see the file libraries/base/LICENSE)
14 --
15 -- Maintainer : libraries@haskell.org
16 -- Stability : experimental
17 -- Portability : portable
18 --
19 -- The 'Typeable' class reifies types to some extent by associating type
20 -- representations to types. These type representations can be compared,
21 -- and one can in turn define a type-safe cast operation. To this end,
22 -- an unsafe cast is guarded by a test for type (representation)
23 -- equivalence. The module "Data.Dynamic" uses Typeable for an
24 -- implementation of dynamics. The module "Data.Generics" uses Typeable
25 -- and type-safe cast (but not dynamics) to support the \"Scrap your
26 -- boilerplate\" style of generic programming.
27 --
28 -----------------------------------------------------------------------------
29
30 module Data.Typeable
31 (
32
33 -- * The Typeable class
34 Typeable( typeOf ), -- :: a -> TypeRep
35
36 -- * Type-safe cast
37 cast, -- :: (Typeable a, Typeable b) => a -> Maybe b
38 gcast, -- a generalisation of cast
39
40 -- * Type representations
41 TypeRep, -- abstract, instance of: Eq, Show, Typeable
42 TyCon, -- abstract, instance of: Eq, Show, Typeable
43 showsTypeRep,
44
45 -- * Construction of type representations
46 mkTyCon, -- :: String -> TyCon
47 mkTyConApp, -- :: TyCon -> [TypeRep] -> TypeRep
48 mkAppTy, -- :: TypeRep -> TypeRep -> TypeRep
49 mkFunTy, -- :: TypeRep -> TypeRep -> TypeRep
50
51 -- * Observation of type representations
52 splitTyConApp, -- :: TypeRep -> (TyCon, [TypeRep])
53 funResultTy, -- :: TypeRep -> TypeRep -> Maybe TypeRep
54 typeRepTyCon, -- :: TypeRep -> TyCon
55 typeRepArgs, -- :: TypeRep -> [TypeRep]
56 tyConString, -- :: TyCon -> String
57 typeRepKey, -- :: TypeRep -> IO Int
58
59 -- * The other Typeable classes
60 -- | /Note:/ The general instances are provided for GHC only.
61 Typeable1( typeOf1 ), -- :: t a -> TypeRep
62 Typeable2( typeOf2 ), -- :: t a b -> TypeRep
63 Typeable3( typeOf3 ), -- :: t a b c -> TypeRep
64 Typeable4( typeOf4 ), -- :: t a b c d -> TypeRep
65 Typeable5( typeOf5 ), -- :: t a b c d e -> TypeRep
66 Typeable6( typeOf6 ), -- :: t a b c d e f -> TypeRep
67 Typeable7( typeOf7 ), -- :: t a b c d e f g -> TypeRep
68 gcast1, -- :: ... => c (t a) -> Maybe (c (t' a))
69 gcast2, -- :: ... => c (t a b) -> Maybe (c (t' a b))
70
71 -- * Default instances
72 -- | /Note:/ These are not needed by GHC, for which these instances
73 -- are generated by general instance declarations.
74 typeOfDefault, -- :: (Typeable1 t, Typeable a) => t a -> TypeRep
75 typeOf1Default, -- :: (Typeable2 t, Typeable a) => t a b -> TypeRep
76 typeOf2Default, -- :: (Typeable3 t, Typeable a) => t a b c -> TypeRep
77 typeOf3Default, -- :: (Typeable4 t, Typeable a) => t a b c d -> TypeRep
78 typeOf4Default, -- :: (Typeable5 t, Typeable a) => t a b c d e -> TypeRep
79 typeOf5Default, -- :: (Typeable6 t, Typeable a) => t a b c d e f -> TypeRep
80 typeOf6Default -- :: (Typeable7 t, Typeable a) => t a b c d e f g -> TypeRep
81
82 ) where
83
84 import qualified Data.HashTable as HT
85 import Data.Maybe
86 import Data.Int
87 import Data.Word
88 import Data.List( foldl, intersperse )
89 import Unsafe.Coerce
90
91 #ifdef __GLASGOW_HASKELL__
92 import GHC.Base
93 import GHC.Show (Show(..), ShowS,
94 shows, showString, showChar, showParen)
95 import GHC.Err (undefined)
96 import GHC.Num (Integer, fromInteger, (+))
97 import GHC.Float (Float, Double)
98 import GHC.Real ( rem, Ratio )
99 import GHC.IOBase (IORef,newIORef,unsafePerformIO)
100
101 -- These imports are so we can define Typeable instances
102 -- It'd be better to give Typeable instances in the modules themselves
103 -- but they all have to be compiled before Typeable
104 import GHC.IOBase ( IO, MVar, Handle, block )
105 import GHC.ST ( ST )
106 import GHC.STRef ( STRef )
107 import GHC.Ptr ( Ptr, FunPtr )
108 import GHC.Stable ( StablePtr, newStablePtr, freeStablePtr,
109 deRefStablePtr, castStablePtrToPtr,
110 castPtrToStablePtr )
111 import GHC.Arr ( Array, STArray )
112
113 #endif
114
115 #ifdef __HUGS__
116 import Hugs.Prelude ( Key(..), TypeRep(..), TyCon(..), Ratio,
117 Exception, ArithException, IOException,
118 ArrayException, AsyncException, Handle,
119 Ptr, FunPtr, ForeignPtr, StablePtr )
120 import Hugs.IORef ( IORef, newIORef, readIORef, writeIORef )
121 import Hugs.IOExts ( unsafePerformIO )
122 -- For the Typeable instance
123 import Hugs.Array ( Array )
124 import Hugs.ConcBase ( MVar )
125 #endif
126
127 #ifdef __NHC__
128 import NHC.IOExtras (IORef,newIORef,readIORef,writeIORef,unsafePerformIO)
129 import IO (Handle)
130 import Ratio (Ratio)
131 -- For the Typeable instance
132 import NHC.FFI ( Ptr,FunPtr,StablePtr,ForeignPtr )
133 import Array ( Array )
134 #endif
135
136 #include "Typeable.h"
137
138 #ifndef __HUGS__
139
140 -------------------------------------------------------------
141 --
142 -- Type representations
143 --
144 -------------------------------------------------------------
145
146 -- | A concrete representation of a (monomorphic) type. 'TypeRep'
147 -- supports reasonably efficient equality.
148 data TypeRep = TypeRep !Key TyCon [TypeRep]
149
150 -- Compare keys for equality
151 instance Eq TypeRep where
152 (TypeRep k1 _ _) == (TypeRep k2 _ _) = k1 == k2
153
154 -- | An abstract representation of a type constructor. 'TyCon' objects can
155 -- be built using 'mkTyCon'.
156 data TyCon = TyCon !Key String
157
158 instance Eq TyCon where
159 (TyCon t1 _) == (TyCon t2 _) = t1 == t2
160 #endif
161
162 -- | Returns a unique integer associated with a 'TypeRep'. This can
163 -- be used for making a mapping with TypeReps
164 -- as the keys, for example. It is guaranteed that @t1 == t2@ if and only if
165 -- @typeRepKey t1 == typeRepKey t2@.
166 --
167 -- It is in the 'IO' monad because the actual value of the key may
168 -- vary from run to run of the program. You should only rely on
169 -- the equality property, not any actual key value. The relative ordering
170 -- of keys has no meaning either.
171 --
172 typeRepKey :: TypeRep -> IO Int
173 typeRepKey (TypeRep (Key i) _ _) = return i
174
175 --
176 -- let fTy = mkTyCon "Foo" in show (mkTyConApp (mkTyCon ",,")
177 -- [fTy,fTy,fTy])
178 --
179 -- returns "(Foo,Foo,Foo)"
180 --
181 -- The TypeRep Show instance promises to print tuple types
182 -- correctly. Tuple type constructors are specified by a
183 -- sequence of commas, e.g., (mkTyCon ",,,,") returns
184 -- the 5-tuple tycon.
185
186 ----------------- Construction --------------------
187
188 -- | Applies a type constructor to a sequence of types
189 mkTyConApp :: TyCon -> [TypeRep] -> TypeRep
190 mkTyConApp tc@(TyCon tc_k _) args
191 = TypeRep (appKeys tc_k arg_ks) tc args
192 where
193 arg_ks = [k | TypeRep k _ _ <- args]
194
195 -- | A special case of 'mkTyConApp', which applies the function
196 -- type constructor to a pair of types.
197 mkFunTy :: TypeRep -> TypeRep -> TypeRep
198 mkFunTy f a = mkTyConApp funTc [f,a]
199
200 -- | Splits a type constructor application
201 splitTyConApp :: TypeRep -> (TyCon,[TypeRep])
202 splitTyConApp (TypeRep _ tc trs) = (tc,trs)
203
204 -- | Applies a type to a function type. Returns: @'Just' u@ if the
205 -- first argument represents a function of type @t -> u@ and the
206 -- second argument represents a function of type @t@. Otherwise,
207 -- returns 'Nothing'.
208 funResultTy :: TypeRep -> TypeRep -> Maybe TypeRep
209 funResultTy trFun trArg
210 = case splitTyConApp trFun of
211 (tc, [t1,t2]) | tc == funTc && t1 == trArg -> Just t2
212 _ -> Nothing
213
214 -- | Adds a TypeRep argument to a TypeRep.
215 mkAppTy :: TypeRep -> TypeRep -> TypeRep
216 mkAppTy (TypeRep tr_k tc trs) arg_tr
217 = let (TypeRep arg_k _ _) = arg_tr
218 in TypeRep (appKey tr_k arg_k) tc (trs++[arg_tr])
219
220 -- If we enforce the restriction that there is only one
221 -- @TyCon@ for a type & it is shared among all its uses,
222 -- we can map them onto Ints very simply. The benefit is,
223 -- of course, that @TyCon@s can then be compared efficiently.
224
225 -- Provided the implementor of other @Typeable@ instances
226 -- takes care of making all the @TyCon@s CAFs (toplevel constants),
227 -- this will work.
228
229 -- If this constraint does turn out to be a sore thumb, changing
230 -- the Eq instance for TyCons is trivial.
231
232 -- | Builds a 'TyCon' object representing a type constructor. An
233 -- implementation of "Data.Typeable" should ensure that the following holds:
234 --
235 -- > mkTyCon "a" == mkTyCon "a"
236 --
237
238 mkTyCon :: String -- ^ the name of the type constructor (should be unique
239 -- in the program, so it might be wise to use the
240 -- fully qualified name).
241 -> TyCon -- ^ A unique 'TyCon' object
242 mkTyCon str = TyCon (mkTyConKey str) str
243
244 ----------------- Observation ---------------------
245
246 -- | Observe the type constructor of a type representation
247 typeRepTyCon :: TypeRep -> TyCon
248 typeRepTyCon (TypeRep _ tc _) = tc
249
250 -- | Observe the argument types of a type representation
251 typeRepArgs :: TypeRep -> [TypeRep]
252 typeRepArgs (TypeRep _ _ args) = args
253
254 -- | Observe string encoding of a type representation
255 tyConString :: TyCon -> String
256 tyConString (TyCon _ str) = str
257
258 ----------------- Showing TypeReps --------------------
259
260 instance Show TypeRep where
261 showsPrec p (TypeRep _ tycon tys) =
262 case tys of
263 [] -> showsPrec p tycon
264 [x] | tycon == listTc -> showChar '[' . shows x . showChar ']'
265 [a,r] | tycon == funTc -> showParen (p > 8) $
266 showsPrec 9 a .
267 showString " -> " .
268 showsPrec 8 r
269 xs | isTupleTyCon tycon -> showTuple xs
270 | otherwise ->
271 showParen (p > 9) $
272 showsPrec p tycon .
273 showChar ' ' .
274 showArgs tys
275
276 showsTypeRep :: TypeRep -> ShowS
277 showsTypeRep = shows
278
279 instance Show TyCon where
280 showsPrec _ (TyCon _ s) = showString s
281
282 isTupleTyCon :: TyCon -> Bool
283 isTupleTyCon (TyCon _ ('(':',':_)) = True
284 isTupleTyCon _ = False
285
286 -- Some (Show.TypeRep) helpers:
287
288 showArgs :: Show a => [a] -> ShowS
289 showArgs [] = id
290 showArgs [a] = showsPrec 10 a
291 showArgs (a:as) = showsPrec 10 a . showString " " . showArgs as
292
293 showTuple :: [TypeRep] -> ShowS
294 showTuple args = showChar '('
295 . (foldr (.) id $ intersperse (showChar ',')
296 $ map (showsPrec 10) args)
297 . showChar ')'
298
299 -------------------------------------------------------------
300 --
301 -- The Typeable class and friends
302 --
303 -------------------------------------------------------------
304
305 -- | The class 'Typeable' allows a concrete representation of a type to
306 -- be calculated.
307 class Typeable a where
308 typeOf :: a -> TypeRep
309 -- ^ Takes a value of type @a@ and returns a concrete representation
310 -- of that type. The /value/ of the argument should be ignored by
311 -- any instance of 'Typeable', so that it is safe to pass 'undefined' as
312 -- the argument.
313
314 -- | Variant for unary type constructors
315 class Typeable1 t where
316 typeOf1 :: t a -> TypeRep
317
318 -- | For defining a 'Typeable' instance from any 'Typeable1' instance.
319 typeOfDefault :: (Typeable1 t, Typeable a) => t a -> TypeRep
320 typeOfDefault x = typeOf1 x `mkAppTy` typeOf (argType x)
321 where
322 argType :: t a -> a
323 argType = undefined
324
325 -- | Variant for binary type constructors
326 class Typeable2 t where
327 typeOf2 :: t a b -> TypeRep
328
329 -- | For defining a 'Typeable1' instance from any 'Typeable2' instance.
330 typeOf1Default :: (Typeable2 t, Typeable a) => t a b -> TypeRep
331 typeOf1Default x = typeOf2 x `mkAppTy` typeOf (argType x)
332 where
333 argType :: t a b -> a
334 argType = undefined
335
336 -- | Variant for 3-ary type constructors
337 class Typeable3 t where
338 typeOf3 :: t a b c -> TypeRep
339
340 -- | For defining a 'Typeable2' instance from any 'Typeable3' instance.
341 typeOf2Default :: (Typeable3 t, Typeable a) => t a b c -> TypeRep
342 typeOf2Default x = typeOf3 x `mkAppTy` typeOf (argType x)
343 where
344 argType :: t a b c -> a
345 argType = undefined
346
347 -- | Variant for 4-ary type constructors
348 class Typeable4 t where
349 typeOf4 :: t a b c d -> TypeRep
350
351 -- | For defining a 'Typeable3' instance from any 'Typeable4' instance.
352 typeOf3Default :: (Typeable4 t, Typeable a) => t a b c d -> TypeRep
353 typeOf3Default x = typeOf4 x `mkAppTy` typeOf (argType x)
354 where
355 argType :: t a b c d -> a
356 argType = undefined
357
358 -- | Variant for 5-ary type constructors
359 class Typeable5 t where
360 typeOf5 :: t a b c d e -> TypeRep
361
362 -- | For defining a 'Typeable4' instance from any 'Typeable5' instance.
363 typeOf4Default :: (Typeable5 t, Typeable a) => t a b c d e -> TypeRep
364 typeOf4Default x = typeOf5 x `mkAppTy` typeOf (argType x)
365 where
366 argType :: t a b c d e -> a
367 argType = undefined
368
369 -- | Variant for 6-ary type constructors
370 class Typeable6 t where
371 typeOf6 :: t a b c d e f -> TypeRep
372
373 -- | For defining a 'Typeable5' instance from any 'Typeable6' instance.
374 typeOf5Default :: (Typeable6 t, Typeable a) => t a b c d e f -> TypeRep
375 typeOf5Default x = typeOf6 x `mkAppTy` typeOf (argType x)
376 where
377 argType :: t a b c d e f -> a
378 argType = undefined
379
380 -- | Variant for 7-ary type constructors
381 class Typeable7 t where
382 typeOf7 :: t a b c d e f g -> TypeRep
383
384 -- | For defining a 'Typeable6' instance from any 'Typeable7' instance.
385 typeOf6Default :: (Typeable7 t, Typeable a) => t a b c d e f g -> TypeRep
386 typeOf6Default x = typeOf7 x `mkAppTy` typeOf (argType x)
387 where
388 argType :: t a b c d e f g -> a
389 argType = undefined
390
391 #ifdef __GLASGOW_HASKELL__
392 -- Given a @Typeable@/n/ instance for an /n/-ary type constructor,
393 -- define the instances for partial applications.
394 -- Programmers using non-GHC implementations must do this manually
395 -- for each type constructor.
396 -- (The INSTANCE_TYPEABLE/n/ macros in Typeable.h include this.)
397
398 -- | One Typeable instance for all Typeable1 instances
399 instance (Typeable1 s, Typeable a)
400 => Typeable (s a) where
401 typeOf = typeOfDefault
402
403 -- | One Typeable1 instance for all Typeable2 instances
404 instance (Typeable2 s, Typeable a)
405 => Typeable1 (s a) where
406 typeOf1 = typeOf1Default
407
408 -- | One Typeable2 instance for all Typeable3 instances
409 instance (Typeable3 s, Typeable a)
410 => Typeable2 (s a) where
411 typeOf2 = typeOf2Default
412
413 -- | One Typeable3 instance for all Typeable4 instances
414 instance (Typeable4 s, Typeable a)
415 => Typeable3 (s a) where
416 typeOf3 = typeOf3Default
417
418 -- | One Typeable4 instance for all Typeable5 instances
419 instance (Typeable5 s, Typeable a)
420 => Typeable4 (s a) where
421 typeOf4 = typeOf4Default
422
423 -- | One Typeable5 instance for all Typeable6 instances
424 instance (Typeable6 s, Typeable a)
425 => Typeable5 (s a) where
426 typeOf5 = typeOf5Default
427
428 -- | One Typeable6 instance for all Typeable7 instances
429 instance (Typeable7 s, Typeable a)
430 => Typeable6 (s a) where
431 typeOf6 = typeOf6Default
432
433 #endif /* __GLASGOW_HASKELL__ */
434
435 -------------------------------------------------------------
436 --
437 -- Type-safe cast
438 --
439 -------------------------------------------------------------
440
441 -- | The type-safe cast operation
442 cast :: (Typeable a, Typeable b) => a -> Maybe b
443 cast x = r
444 where
445 r = if typeOf x == typeOf (fromJust r)
446 then Just $ unsafeCoerce x
447 else Nothing
448
449 -- | A flexible variation parameterised in a type constructor
450 gcast :: (Typeable a, Typeable b) => c a -> Maybe (c b)
451 gcast x = r
452 where
453 r = if typeOf (getArg x) == typeOf (getArg (fromJust r))
454 then Just $ unsafeCoerce x
455 else Nothing
456 getArg :: c x -> x
457 getArg = undefined
458
459 -- | Cast for * -> *
460 gcast1 :: (Typeable1 t, Typeable1 t') => c (t a) -> Maybe (c (t' a))
461 gcast1 x = r
462 where
463 r = if typeOf1 (getArg x) == typeOf1 (getArg (fromJust r))
464 then Just $ unsafeCoerce x
465 else Nothing
466 getArg :: c x -> x
467 getArg = undefined
468
469 -- | Cast for * -> * -> *
470 gcast2 :: (Typeable2 t, Typeable2 t') => c (t a b) -> Maybe (c (t' a b))
471 gcast2 x = r
472 where
473 r = if typeOf2 (getArg x) == typeOf2 (getArg (fromJust r))
474 then Just $ unsafeCoerce x
475 else Nothing
476 getArg :: c x -> x
477 getArg = undefined
478
479 -------------------------------------------------------------
480 --
481 -- Instances of the Typeable classes for Prelude types
482 --
483 -------------------------------------------------------------
484
485 INSTANCE_TYPEABLE0((),unitTc,"()")
486 INSTANCE_TYPEABLE1([],listTc,"[]")
487 INSTANCE_TYPEABLE1(Maybe,maybeTc,"Maybe")
488 INSTANCE_TYPEABLE1(Ratio,ratioTc,"Ratio")
489 INSTANCE_TYPEABLE2((->),funTc,"->")
490 INSTANCE_TYPEABLE1(IO,ioTc,"IO")
491
492 #if defined(__GLASGOW_HASKELL__) || defined(__HUGS__)
493 -- Types defined in GHC.IOBase
494 INSTANCE_TYPEABLE1(MVar,mvarTc,"MVar" )
495 #endif
496
497 -- Types defined in GHC.Arr
498 INSTANCE_TYPEABLE2(Array,arrayTc,"Array")
499
500 #ifdef __GLASGOW_HASKELL__
501 -- Hugs has these too, but their Typeable<n> instances are defined
502 -- elsewhere to keep this module within Haskell 98.
503 -- This is important because every invocation of runhugs or ffihugs
504 -- uses this module via Data.Dynamic.
505 INSTANCE_TYPEABLE2(ST,stTc,"ST")
506 INSTANCE_TYPEABLE2(STRef,stRefTc,"STRef")
507 INSTANCE_TYPEABLE3(STArray,sTArrayTc,"STArray")
508 #endif
509
510 #ifndef __NHC__
511 INSTANCE_TYPEABLE2((,),pairTc,"(,)")
512 INSTANCE_TYPEABLE3((,,),tup3Tc,"(,,)")
513
514 tup4Tc :: TyCon
515 tup4Tc = mkTyCon "(,,,)"
516
517 instance Typeable4 (,,,) where
518 typeOf4 _ = mkTyConApp tup4Tc []
519
520 tup5Tc :: TyCon
521 tup5Tc = mkTyCon "(,,,,)"
522
523 instance Typeable5 (,,,,) where
524 typeOf5 _ = mkTyConApp tup5Tc []
525
526 tup6Tc :: TyCon
527 tup6Tc = mkTyCon "(,,,,,)"
528
529 instance Typeable6 (,,,,,) where
530 typeOf6 _ = mkTyConApp tup6Tc []
531
532 tup7Tc :: TyCon
533 tup7Tc = mkTyCon "(,,,,,,)"
534
535 instance Typeable7 (,,,,,,) where
536 typeOf7 _ = mkTyConApp tup7Tc []
537 #endif /* __NHC__ */
538
539 INSTANCE_TYPEABLE1(Ptr,ptrTc,"Ptr")
540 INSTANCE_TYPEABLE1(FunPtr,funPtrTc,"FunPtr")
541 INSTANCE_TYPEABLE1(StablePtr,stablePtrTc,"StablePtr")
542 INSTANCE_TYPEABLE1(IORef,iORefTc,"IORef")
543
544 -------------------------------------------------------
545 --
546 -- Generate Typeable instances for standard datatypes
547 --
548 -------------------------------------------------------
549
550 INSTANCE_TYPEABLE0(Bool,boolTc,"Bool")
551 INSTANCE_TYPEABLE0(Char,charTc,"Char")
552 INSTANCE_TYPEABLE0(Float,floatTc,"Float")
553 INSTANCE_TYPEABLE0(Double,doubleTc,"Double")
554 INSTANCE_TYPEABLE0(Int,intTc,"Int")
555 #ifndef __NHC__
556 INSTANCE_TYPEABLE0(Word,wordTc,"Word" )
557 #endif
558 INSTANCE_TYPEABLE0(Integer,integerTc,"Integer")
559 INSTANCE_TYPEABLE0(Ordering,orderingTc,"Ordering")
560 INSTANCE_TYPEABLE0(Handle,handleTc,"Handle")
561
562 INSTANCE_TYPEABLE0(Int8,int8Tc,"Int8")
563 INSTANCE_TYPEABLE0(Int16,int16Tc,"Int16")
564 INSTANCE_TYPEABLE0(Int32,int32Tc,"Int32")
565 INSTANCE_TYPEABLE0(Int64,int64Tc,"Int64")
566
567 INSTANCE_TYPEABLE0(Word8,word8Tc,"Word8" )
568 INSTANCE_TYPEABLE0(Word16,word16Tc,"Word16")
569 INSTANCE_TYPEABLE0(Word32,word32Tc,"Word32")
570 INSTANCE_TYPEABLE0(Word64,word64Tc,"Word64")
571
572 INSTANCE_TYPEABLE0(TyCon,tyconTc,"TyCon")
573 INSTANCE_TYPEABLE0(TypeRep,typeRepTc,"TypeRep")
574
575 #ifdef __GLASGOW_HASKELL__
576 INSTANCE_TYPEABLE0(RealWorld,realWorldTc,"RealWorld")
577 #endif
578
579 ---------------------------------------------
580 --
581 -- Internals
582 --
583 ---------------------------------------------
584
585 #ifndef __HUGS__
586 newtype Key = Key Int deriving( Eq )
587 #endif
588
589 data KeyPr = KeyPr !Key !Key deriving( Eq )
590
591 hashKP :: KeyPr -> Int32
592 hashKP (KeyPr (Key k1) (Key k2)) = (HT.hashInt k1 + HT.hashInt k2) `rem` HT.prime
593
594 data Cache = Cache { next_key :: !(IORef Key), -- Not used by GHC (calls genSym instead)
595 tc_tbl :: !(HT.HashTable String Key),
596 ap_tbl :: !(HT.HashTable KeyPr Key) }
597
598 {-# NOINLINE cache #-}
599 #ifdef __GLASGOW_HASKELL__
600 foreign import ccall unsafe "RtsTypeable.h getOrSetTypeableStore"
601 getOrSetTypeableStore :: Ptr a -> IO (Ptr a)
602 #endif
603
604 cache :: Cache
605 cache = unsafePerformIO $ do
606 empty_tc_tbl <- HT.new (==) HT.hashString
607 empty_ap_tbl <- HT.new (==) hashKP
608 key_loc <- newIORef (Key 1)
609 let ret = Cache { next_key = key_loc,
610 tc_tbl = empty_tc_tbl,
611 ap_tbl = empty_ap_tbl }
612 #ifdef __GLASGOW_HASKELL__
613 block $ do
614 stable_ref <- newStablePtr ret
615 let ref = castStablePtrToPtr stable_ref
616 ref2 <- getOrSetTypeableStore ref
617 if ref==ref2
618 then deRefStablePtr stable_ref
619 else do
620 freeStablePtr stable_ref
621 deRefStablePtr
622 (castPtrToStablePtr ref2)
623 #else
624 return ret
625 #endif
626
627 newKey :: IORef Key -> IO Key
628 #ifdef __GLASGOW_HASKELL__
629 newKey _ = do i <- genSym; return (Key i)
630 #else
631 newKey kloc = do { k@(Key i) <- readIORef kloc ;
632 writeIORef kloc (Key (i+1)) ;
633 return k }
634 #endif
635
636 #ifdef __GLASGOW_HASKELL__
637 foreign import ccall unsafe "genSymZh"
638 genSym :: IO Int
639 #endif
640
641 mkTyConKey :: String -> Key
642 mkTyConKey str
643 = unsafePerformIO $ do
644 let Cache {next_key = kloc, tc_tbl = tbl} = cache
645 mb_k <- HT.lookup tbl str
646 case mb_k of
647 Just k -> return k
648 Nothing -> do { k <- newKey kloc ;
649 HT.insert tbl str k ;
650 return k }
651
652 appKey :: Key -> Key -> Key
653 appKey k1 k2
654 = unsafePerformIO $ do
655 let Cache {next_key = kloc, ap_tbl = tbl} = cache
656 mb_k <- HT.lookup tbl kpr
657 case mb_k of
658 Just k -> return k
659 Nothing -> do { k <- newKey kloc ;
660 HT.insert tbl kpr k ;
661 return k }
662 where
663 kpr = KeyPr k1 k2
664
665 appKeys :: Key -> [Key] -> Key
666 appKeys k ks = foldl appKey k ks