+++ /dev/null
-%
-% (c) The GRASP Project, Glasgow University, 1994-1998
-%
-\section[BitSet]{An implementation of very small sets}
-
-Bit sets are a fast implementation of sets of integers ranging from 0
-to one less than the number of bits in a machine word (typically 31).
-If any element exceeds the maximum value for a particular machine
-architecture, the results of these operations are undefined. You have
-been warned. If you put any safety checks in this code, I will have
-to kill you.
-
-Note: the Yale Haskell implementation won't provide a full 32 bits.
-However, if you can handle the performance loss, you could change to
-Integer and get virtually unlimited sets.
-
-\begin{code}
-
-module BitSet (
- BitSet, -- abstract type
- mkBS, listBS, emptyBS, unitBS,
- unionBS, minusBS, intBS
- ) where
-
-#include "HsVersions.h"
-
-#ifdef __GLASGOW_HASKELL__
-import GLAEXTS
--- nothing to import
-#elif defined(__YALE_HASKELL__)
-{-hide import from mkdependHS-}
-import
- LogOpPrims
-#else
-{-hide import from mkdependHS-}
-import
- Word
-#endif
-
-#ifdef __GLASGOW_HASKELL__
-
-data BitSet = MkBS Word#
-
-emptyBS :: BitSet
-emptyBS = MkBS (int2Word# 0#)
-
-mkBS :: [Int] -> BitSet
-mkBS xs = foldr (unionBS . unitBS) emptyBS xs
-
-unitBS :: Int -> BitSet
-unitBS x = case x of
-#if __GLASGOW_HASKELL__ >= 503
- I# i# -> MkBS ((int2Word# 1#) `uncheckedShiftL#` i#)
-#else
- I# i# -> MkBS ((int2Word# 1#) `shiftL#` i#)
-#endif
-
-unionBS :: BitSet -> BitSet -> BitSet
-unionBS (MkBS x#) (MkBS y#) = MkBS (x# `or#` y#)
-
-minusBS :: BitSet -> BitSet -> BitSet
-minusBS (MkBS x#) (MkBS y#) = MkBS (x# `and#` (not# y#))
-
-#if 0
--- not used in GHC
-isEmptyBS :: BitSet -> Bool
-isEmptyBS (MkBS s#)
- = case word2Int# s# of
- 0# -> True
- _ -> False
-
-intersectBS :: BitSet -> BitSet -> BitSet
-intersectBS (MkBS x#) (MkBS y#) = MkBS (x# `and#` y#)
-
-elementBS :: Int -> BitSet -> Bool
-elementBS x (MkBS s#) = case x of
- I# i# -> case word2Int# (((int2Word# 1#) `shiftL#` i#) `and#` s#) of
- 0# -> False
- _ -> True
-#endif
-
-listBS :: BitSet -> [Int]
-listBS s = listify s 0
- where listify (MkBS s#) n =
- case word2Int# s# of
- 0# -> []
- _ -> let s' = (MkBS (s# `shiftr` 1#))
- more = listify s' (n + 1)
- in case word2Int# (s# `and#` (int2Word# 1#)) of
- 0# -> more
- _ -> n : more
-#if __GLASGOW_HASKELL__ >= 503
- shiftr x y = uncheckedShiftRL# x y
-#else
- shiftr x y = shiftRL# x y
-#endif
-
--- intBS is a bit naughty.
-intBS :: BitSet -> Int
-intBS (MkBS w#) = I# (word2Int# w#)
-
-#elif defined(__YALE_HASKELL__)
-
-data BitSet = MkBS Int
-
-emptyBS :: BitSet
-emptyBS = MkBS 0
-
-mkBS :: [Int] -> BitSet
-mkBS xs = foldr (unionBS . unitBS) emptyBS xs
-
-unitBS :: Int -> BitSet
-unitBS x = MkBS (1 `ashInt` x)
-
-unionBS :: BitSet -> BitSet -> BitSet
-unionBS (MkBS x) (MkBS y) = MkBS (x `logiorInt` y)
-
-#if 0
--- not used in GHC
-isEmptyBS :: BitSet -> Bool
-isEmptyBS (MkBS s)
- = case s of
- 0 -> True
- _ -> False
-
-intersectBS :: BitSet -> BitSet -> BitSet
-intersectBS (MkBS x) (MkBS y) = MkBS (x `logandInt` y)
-
-elementBS :: Int -> BitSet -> Bool
-elementBS x (MkBS s)
- = case logbitpInt x s of
- 0 -> False
- _ -> True
-#endif
-
-minusBS :: BitSet -> BitSet -> BitSet
-minusBS (MkBS x) (MkBS y) = MkBS (x `logandc2Int` y)
-
--- rewritten to avoid right shifts (which would give nonsense on negative
--- values.
-listBS :: BitSet -> [Int]
-listBS (MkBS s) = listify s 0 1
- where listify s n m =
- case s of
- 0 -> []
- _ -> let n' = n+1; m' = m+m in
- case logbitpInt s m of
- 0 -> listify s n' m'
- _ -> n : listify (s `logandc2Int` m) n' m'
-
-#else /* HBC, perhaps? */
-
-data BitSet = MkBS Word
-
-emptyBS :: BitSet
-emptyBS = MkBS 0
-
-mkBS :: [Int] -> BitSet
-mkBS xs = foldr (unionBS . unitBS) emptyBS xs
-
-unitBS :: Int -> BitSet
-unitBS x = MkBS (1 `bitLsh` x)
-
-unionBS :: BitSet -> BitSet -> BitSet
-unionBS (MkBS x) (MkBS y) = MkBS (x `bitOr` y)
-
-#if 0
--- not used in GHC
-isEmptyBS :: BitSet -> Bool
-isEmptyBS (MkBS s)
- = case s of
- 0 -> True
- _ -> False
-
-intersectBS :: BitSet -> BitSet -> BitSet
-intersectBS (MkBS x) (MkBS y) = MkBS (x `bitAnd` y)
-
-elementBS :: Int -> BitSet -> Bool
-elementBS x (MkBS s)
- = case (1 `bitLsh` x) `bitAnd` s of
- 0 -> False
- _ -> True
-#endif
-
-minusBS :: BitSet -> BitSet -> BitSet
-minusBS (MkBS x) (MkBS y) = MkBS (x `bitAnd` (bitCompl y))
-
-listBS :: BitSet -> [Int]
-listBS (MkBS s) = listify s 0
- where listify s n =
- case s of
- 0 -> []
- _ -> let s' = s `bitRsh` 1
- more = listify s' (n + 1)
- in case (s `bitAnd` 1) of
- 0 -> more
- _ -> n : more
-
-#endif
-
-\end{code}
-
-
-
-