2 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
4 \section[UniqSupply]{The @UniqueSupply@ data type and a (monadic) supply thereof}
9 UniqSupply, -- Abstractly
11 uniqFromSupply, uniqsFromSupply, -- basic ops
13 UniqSM, -- type: unique supply monad
14 initUs, initUs_, thenUs, thenUs_, returnUs, fixUs, getUs, setUs,
15 getUniqueUs, getUniquesUs,
16 mapUs, mapAndUnzipUs, mapAndUnzip3Us,
17 thenMaybeUs, mapAccumLUs,
23 #include "HsVersions.h"
26 import Panic ( panic )
30 #if __GLASGOW_HASKELL__ < 301
31 import IOBase ( IO(..), IOResult(..) )
41 %************************************************************************
43 \subsection{Splittable Unique supply: @UniqSupply@}
45 %************************************************************************
47 %************************************************************************
49 \subsubsection[UniqSupply-type]{@UniqSupply@ type and operations}
51 %************************************************************************
53 A value of type @UniqSupply@ is unique, and it can
54 supply {\em one} distinct @Unique@. Also, from the supply, one can
55 also manufacture an arbitrary number of further @UniqueSupplies@,
56 which will be distinct from the first and from all others.
60 = MkSplitUniqSupply Int -- make the Unique with this
62 -- when split => these two supplies
66 mkSplitUniqSupply :: Char -> IO UniqSupply
68 splitUniqSupply :: UniqSupply -> (UniqSupply, UniqSupply)
69 uniqFromSupply :: UniqSupply -> Unique
70 uniqsFromSupply :: Int -> UniqSupply -> [Unique]
74 mkSplitUniqSupply (C# c#)
76 mask# = (i2w (ord# c#)) `shiftL#` (i2w_s 24#)
78 -- here comes THE MAGIC:
80 -- This is one of the most hammered bits in the whole compiler
82 = unsafeInterleaveIO (
83 mk_unique >>= \ uniq ->
84 mk_supply# >>= \ s1 ->
85 mk_supply# >>= \ s2 ->
86 return (MkSplitUniqSupply uniq s1 s2)
89 mk_unique = _ccall_ genSymZh >>= \ (W# u#) ->
90 return (I# (w2i (mask# `or#` u#)))
94 splitUniqSupply (MkSplitUniqSupply _ s1 s2) = (s1, s2)
98 uniqFromSupply (MkSplitUniqSupply (I# n) _ _) = mkUniqueGrimily n
100 uniqsFromSupply (I# i) supply = i `get_from` supply
103 get_from n (MkSplitUniqSupply (I# u) _ s2)
104 = mkUniqueGrimily u : get_from (n -# 1#) s2
107 %************************************************************************
109 \subsubsection[UniqSupply-monad]{@UniqSupply@ monad: @UniqSM@}
111 %************************************************************************
114 type UniqSM result = UniqSupply -> (result, UniqSupply)
116 -- the initUs function also returns the final UniqSupply; initUs_ drops it
117 initUs :: UniqSupply -> UniqSM a -> (a,UniqSupply)
118 initUs init_us m = case m init_us of { (r,us) -> (r,us) }
120 initUs_ :: UniqSupply -> UniqSM a -> a
121 initUs_ init_us m = case m init_us of { (r,us) -> r }
123 {-# INLINE thenUs #-}
124 {-# INLINE returnUs #-}
125 {-# INLINE splitUniqSupply #-}
128 @thenUs@ is where we split the @UniqSupply@.
130 fixUs :: (a -> UniqSM a) -> UniqSM a
132 = (r,us') where (r,us') = m r us
134 thenUs :: UniqSM a -> (a -> UniqSM b) -> UniqSM b
136 = case (expr us) of { (result, us') -> cont result us' }
138 thenUs_ :: UniqSM a -> UniqSM b -> UniqSM b
140 = case (expr us) of { (_, us') -> cont us' }
142 returnUs :: a -> UniqSM a
143 returnUs result us = (result, us)
145 getUs :: UniqSM UniqSupply
146 getUs us = (us, panic "getUs: bad supply")
148 setUs :: UniqSupply -> UniqSM ()
149 setUs us old_us = ((), us)
151 getUniqueUs :: UniqSM Unique
152 getUniqueUs us = case splitUniqSupply us of
153 (us1,us2) -> (uniqFromSupply us1, us2)
155 getUniquesUs :: Int -> UniqSM [Unique]
156 getUniquesUs n us = case splitUniqSupply us of
157 (us1,us2) -> (uniqsFromSupply n us1, us2)
161 mapUs :: (a -> UniqSM b) -> [a] -> UniqSM [b]
163 mapUs f [] = returnUs []
165 = f x `thenUs` \ r ->
166 mapUs f xs `thenUs` \ rs ->
169 mapAndUnzipUs :: (a -> UniqSM (b,c)) -> [a] -> UniqSM ([b],[c])
170 mapAndUnzip3Us :: (a -> UniqSM (b,c,d)) -> [a] -> UniqSM ([b],[c],[d])
172 mapAndUnzipUs f [] = returnUs ([],[])
173 mapAndUnzipUs f (x:xs)
174 = f x `thenUs` \ (r1, r2) ->
175 mapAndUnzipUs f xs `thenUs` \ (rs1, rs2) ->
176 returnUs (r1:rs1, r2:rs2)
178 mapAndUnzip3Us f [] = returnUs ([],[],[])
179 mapAndUnzip3Us f (x:xs)
180 = f x `thenUs` \ (r1, r2, r3) ->
181 mapAndUnzip3Us f xs `thenUs` \ (rs1, rs2, rs3) ->
182 returnUs (r1:rs1, r2:rs2, r3:rs3)
184 thenMaybeUs :: UniqSM (Maybe a) -> (a -> UniqSM (Maybe b)) -> UniqSM (Maybe b)
186 = m `thenUs` \ result ->
188 Nothing -> returnUs Nothing
191 mapAccumLUs :: (acc -> x -> UniqSM (acc, y))
196 mapAccumLUs f b [] = returnUs (b, [])
197 mapAccumLUs f b (x:xs)
198 = f b x `thenUs` \ (b__2, x__2) ->
199 mapAccumLUs f b__2 xs `thenUs` \ (b__3, xs__2) ->
200 returnUs (b__3, x__2:xs__2)