2 % (c) The University of Glasgow 2006
3 % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
8 VarEnv, IdEnv, TyVarEnv,
9 emptyVarEnv, unitVarEnv, mkVarEnv,
10 elemVarEnv, varEnvElts, varEnvKeys,
11 extendVarEnv, extendVarEnv_C, extendVarEnvList,
12 plusVarEnv, plusVarEnv_C,
13 delVarEnvList, delVarEnv,
14 lookupVarEnv, lookupVarEnv_NF, lookupWithDefaultVarEnv,
16 modifyVarEnv, modifyVarEnv_Directly,
17 isEmptyVarEnv, foldVarEnv,
18 elemVarEnvByKey, lookupVarEnv_Directly,
19 filterVarEnv_Directly,
22 InScopeSet, emptyInScopeSet, mkInScopeSet, delInScopeSet,
23 extendInScopeSet, extendInScopeSetList, extendInScopeSetSet,
25 getInScopeVars, lookupInScope, elemInScopeSet, uniqAway,
27 -- RnEnv2 and its operations
28 RnEnv2, mkRnEnv2, rnBndr2, rnBndrs2, rnOccL, rnOccR, inRnEnvL, inRnEnvR,
29 rnBndrL, rnBndrR, nukeRnEnvL, nukeRnEnvR, extendRnInScopeList,
30 rnInScope, rnInScopeSet, lookupRnInScope,
50 %************************************************************************
54 %************************************************************************
57 data InScopeSet = InScope (VarEnv Var) FastInt
58 -- The Int# is a kind of hash-value used by uniqAway
59 -- For example, it might be the size of the set
60 -- INVARIANT: it's not zero; we use it as a multiplier in uniqAway
62 instance Outputable InScopeSet where
63 ppr (InScope s _) = ptext (sLit "InScope") <+> ppr s
65 emptyInScopeSet :: InScopeSet
66 emptyInScopeSet = InScope emptyVarSet (_ILIT(1))
68 getInScopeVars :: InScopeSet -> VarEnv Var
69 getInScopeVars (InScope vs _) = vs
71 mkInScopeSet :: VarEnv Var -> InScopeSet
72 mkInScopeSet in_scope = InScope in_scope (_ILIT(1))
74 extendInScopeSet :: InScopeSet -> Var -> InScopeSet
75 extendInScopeSet (InScope in_scope n) v = InScope (extendVarEnv in_scope v v) (n +# _ILIT(1))
77 extendInScopeSetList :: InScopeSet -> [Var] -> InScopeSet
78 extendInScopeSetList (InScope in_scope n) vs
79 = InScope (foldl (\s v -> extendVarEnv s v v) in_scope vs)
80 (n +# iUnbox (length vs))
82 extendInScopeSetSet :: InScopeSet -> VarEnv Var -> InScopeSet
83 extendInScopeSetSet (InScope in_scope n) vs
84 = InScope (in_scope `plusVarEnv` vs) (n +# iUnbox (sizeUFM vs))
86 modifyInScopeSet :: InScopeSet -> Var -> Var -> InScopeSet
87 -- Exploit the fact that the in-scope "set" is really a map
88 -- Make old_v map to new_v
89 modifyInScopeSet (InScope in_scope n) old_v new_v = InScope (extendVarEnv in_scope old_v new_v) (n +# _ILIT(1))
91 delInScopeSet :: InScopeSet -> Var -> InScopeSet
92 delInScopeSet (InScope in_scope n) v = InScope (in_scope `delVarEnv` v) n
94 elemInScopeSet :: Var -> InScopeSet -> Bool
95 elemInScopeSet v (InScope in_scope _) = v `elemVarEnv` in_scope
97 lookupInScope :: InScopeSet -> Var -> Maybe Var
98 -- It's important to look for a fixed point
99 -- When we see (case x of y { I# v -> ... })
100 -- we add [x -> y] to the in-scope set (Simplify.simplCaseBinder).
101 -- When we lookup up an occurrence of x, we map to y, but then
102 -- we want to look up y in case it has acquired more evaluation information by now.
103 lookupInScope (InScope in_scope _) v
106 go v = case lookupVarEnv in_scope v of
107 Just v' | v == v' -> Just v' -- Reached a fixed point
113 uniqAway :: InScopeSet -> Var -> Var
114 -- (uniqAway in_scope v) finds a unique that is not used in the
115 -- in-scope set, and gives that to v. It starts with v's current unique, of course,
116 -- in the hope that it won't have to change it, and thereafter uses a combination
117 -- of that and the hash-code found in the in-scope set
118 uniqAway in_scope var
119 | var `elemInScopeSet` in_scope = uniqAway' in_scope var -- Make a new one
120 | otherwise = var -- Nothing to do
122 uniqAway' :: InScopeSet -> Var -> Var
123 -- This one *always* makes up a new variable
124 uniqAway' (InScope set n) var
127 orig_unique = getUnique var
129 | debugIsOn && (k ># _ILIT(1000))
130 = pprPanic "uniqAway loop:" (ppr (iBox k) <+> text "tries" <+> ppr var <+> int (iBox n))
131 | uniq `elemVarSetByKey` set = try (k +# _ILIT(1))
132 | debugIsOn && opt_PprStyle_Debug && (k ># _ILIT(3))
133 = pprTrace "uniqAway:" (ppr (iBox k) <+> text "tries" <+> ppr var <+> int (iBox n))
134 setVarUnique var uniq
135 | otherwise = setVarUnique var uniq
137 uniq = deriveUnique orig_unique (iBox (n *# k))
141 %************************************************************************
145 %************************************************************************
147 When we are comparing (or matching) types or terms, we are faced with
148 "going under" corresponding binders. E.g. when comparing
151 Basically we want to rename [x->y] or [y->x], but there are lots of
152 things we must be careful of. In particular, x might be free in e2, or
153 y in e1. So the idea is that we come up with a fresh binder that is free
154 in neither, and rename x and y respectively. That means we must maintain
155 a) a renaming for the left-hand expression
156 b) a renaming for the right-hand expressions
159 Furthermore, when matching, we want to be able to have an 'occurs check',
162 matching with f->y. So for each expression we want to know that set of
163 locally-bound variables. That is precisely the domain of the mappings (a)
164 and (b), but we must ensure that we always extend the mappings as we go in.
169 = RV2 { envL :: VarEnv Var -- Renaming for Left term
170 , envR :: VarEnv Var -- Renaming for Right term
171 , in_scope :: InScopeSet } -- In scope in left or right terms
173 -- The renamings envL and envR are *guaranteed* to contain a binding
174 -- for every variable bound as we go into the term, even if it is not
175 -- renamed. That way we can ask what variables are locally bound
176 -- (inRnEnvL, inRnEnvR)
178 mkRnEnv2 :: InScopeSet -> RnEnv2
179 mkRnEnv2 vars = RV2 { envL = emptyVarEnv
183 extendRnInScopeList :: RnEnv2 -> [Var] -> RnEnv2
184 extendRnInScopeList env vs
185 = env { in_scope = extendInScopeSetList (in_scope env) vs }
187 rnInScope :: Var -> RnEnv2 -> Bool
188 rnInScope x env = x `elemInScopeSet` in_scope env
190 rnInScopeSet :: RnEnv2 -> InScopeSet
191 rnInScopeSet = in_scope
193 rnBndrs2 :: RnEnv2 -> [Var] -> [Var] -> RnEnv2
194 -- Arg lists must be of equal length
195 rnBndrs2 env bsL bsR = foldl2 rnBndr2 env bsL bsR
197 rnBndr2 :: RnEnv2 -> Var -> Var -> RnEnv2
198 -- (rnBndr2 env bL bR) go under a binder bL in the Left term 1,
199 -- and binder bR in the Right term
200 -- It finds a new binder, new_b,
201 -- and returns an environment mapping bL->new_b and bR->new_b resp.
202 rnBndr2 (RV2 { envL = envL, envR = envR, in_scope = in_scope }) bL bR
203 = RV2 { envL = extendVarEnv envL bL new_b -- See Note
204 , envR = extendVarEnv envR bR new_b -- [Rebinding]
205 , in_scope = extendInScopeSet in_scope new_b }
207 -- Find a new binder not in scope in either term
208 new_b | not (bL `elemInScopeSet` in_scope) = bL
209 | not (bR `elemInScopeSet` in_scope) = bR
210 | otherwise = uniqAway' in_scope bL
213 -- If the new var is the same as the old one, note that
214 -- the extendVarEnv *deletes* any current renaming
215 -- E.g. (\x. \x. ...) ~ (\y. \z. ...)
217 -- Inside \x \y { [x->y], [y->y], {y} }
218 -- \x \z { [x->x], [y->y, z->x], {y,x} }
220 rnBndrL, rnBndrR :: RnEnv2 -> Var -> (RnEnv2, Var)
221 -- Used when there's a binder on one side or the other only
222 -- Useful when eta-expanding
224 rnBndrL (RV2 { envL = envL, envR = envR, in_scope = in_scope }) bL
225 = (RV2 { envL = extendVarEnv envL bL new_b
226 , envR = extendVarEnv envR new_b new_b -- Note [rnBndrLR]
227 , in_scope = extendInScopeSet in_scope new_b }, new_b)
229 new_b = uniqAway in_scope bL
231 rnBndrR (RV2 { envL = envL, envR = envR, in_scope = in_scope }) bR
232 = (RV2 { envL = extendVarEnv envL new_b new_b -- Note [rnBndrLR]
233 , envR = extendVarEnv envR bR new_b
234 , in_scope = extendInScopeSet in_scope new_b }, new_b)
236 new_b = uniqAway in_scope bR
240 -- Notice that in rnBndrL, rnBndrR, we extend envR, envL respectively
241 -- with a binding [new_b -> new_b], where new_b is the new binder.
242 -- This is important when doing eta expansion; e.g. matching (\x.M) ~ N
243 -- In effect we switch to (\x'.M) ~ (\x'.N x'), where x' is new_b
244 -- So we must add x' to the env of both L and R. (x' is fresh, so it
245 -- can't capture anything in N.)
247 -- If we don't do this, we can get silly matches like
248 -- forall a. \y.a ~ v
249 -- succeeding with [x -> v y], which is bogus of course
251 rnOccL, rnOccR :: RnEnv2 -> Var -> Var
252 -- Look up the renaming of an occurrence in the left or right term
253 rnOccL (RV2 { envL = env }) v = lookupVarEnv env v `orElse` v
254 rnOccR (RV2 { envR = env }) v = lookupVarEnv env v `orElse` v
256 inRnEnvL, inRnEnvR :: RnEnv2 -> Var -> Bool
257 -- Tells whether a variable is locally bound
258 inRnEnvL (RV2 { envL = env }) v = v `elemVarEnv` env
259 inRnEnvR (RV2 { envR = env }) v = v `elemVarEnv` env
261 lookupRnInScope :: RnEnv2 -> Var -> Var
262 lookupRnInScope env v = lookupInScope (in_scope env) v `orElse` v
264 nukeRnEnvL, nukeRnEnvR :: RnEnv2 -> RnEnv2
265 nukeRnEnvL env = env { envL = emptyVarEnv }
266 nukeRnEnvR env = env { envR = emptyVarEnv }
270 %************************************************************************
274 %************************************************************************
276 When tidying up print names, we keep a mapping of in-scope occ-names
277 (the TidyOccEnv) and a Var-to-Var of the current renamings.
280 type TidyEnv = (TidyOccEnv, VarEnv Var)
282 emptyTidyEnv :: TidyEnv
283 emptyTidyEnv = (emptyTidyOccEnv, emptyVarEnv)
287 %************************************************************************
289 \subsection{@VarEnv@s}
291 %************************************************************************
294 type VarEnv elt = UniqFM elt
295 type IdEnv elt = VarEnv elt
296 type TyVarEnv elt = VarEnv elt
298 emptyVarEnv :: VarEnv a
299 mkVarEnv :: [(Var, a)] -> VarEnv a
300 zipVarEnv :: [Var] -> [a] -> VarEnv a
301 unitVarEnv :: Var -> a -> VarEnv a
302 extendVarEnv :: VarEnv a -> Var -> a -> VarEnv a
303 extendVarEnv_C :: (a->a->a) -> VarEnv a -> Var -> a -> VarEnv a
304 plusVarEnv :: VarEnv a -> VarEnv a -> VarEnv a
305 extendVarEnvList :: VarEnv a -> [(Var, a)] -> VarEnv a
307 lookupVarEnv_Directly :: VarEnv a -> Unique -> Maybe a
308 filterVarEnv_Directly :: (Unique -> a -> Bool) -> VarEnv a -> VarEnv a
309 delVarEnvList :: VarEnv a -> [Var] -> VarEnv a
310 delVarEnv :: VarEnv a -> Var -> VarEnv a
311 plusVarEnv_C :: (a -> a -> a) -> VarEnv a -> VarEnv a -> VarEnv a
312 mapVarEnv :: (a -> b) -> VarEnv a -> VarEnv b
313 modifyVarEnv :: (a -> a) -> VarEnv a -> Var -> VarEnv a
314 varEnvElts :: VarEnv a -> [a]
315 varEnvKeys :: VarEnv a -> [Unique]
317 isEmptyVarEnv :: VarEnv a -> Bool
318 lookupVarEnv :: VarEnv a -> Var -> Maybe a
319 lookupVarEnv_NF :: VarEnv a -> Var -> a
320 lookupWithDefaultVarEnv :: VarEnv a -> a -> Var -> a
321 elemVarEnv :: Var -> VarEnv a -> Bool
322 elemVarEnvByKey :: Unique -> VarEnv a -> Bool
323 foldVarEnv :: (a -> b -> b) -> b -> VarEnv a -> b
328 elemVarEnvByKey = elemUFM_Directly
329 extendVarEnv = addToUFM
330 extendVarEnv_C = addToUFM_C
331 extendVarEnvList = addListToUFM
332 plusVarEnv_C = plusUFM_C
333 delVarEnvList = delListFromUFM
334 delVarEnv = delFromUFM
336 lookupVarEnv = lookupUFM
337 lookupWithDefaultVarEnv = lookupWithDefaultUFM
340 emptyVarEnv = emptyUFM
344 isEmptyVarEnv = isNullUFM
346 lookupVarEnv_Directly = lookupUFM_Directly
347 filterVarEnv_Directly = filterUFM_Directly
349 zipVarEnv tyvars tys = mkVarEnv (zipEqual "zipVarEnv" tyvars tys)
350 lookupVarEnv_NF env id = case lookupVarEnv env id of
352 Nothing -> panic "lookupVarEnv_NF: Nothing"
355 @modifyVarEnv@: Look up a thing in the VarEnv,
356 then mash it with the modify function, and put it back.
359 modifyVarEnv mangle_fn env key
360 = case (lookupVarEnv env key) of
362 Just xx -> extendVarEnv env key (mangle_fn xx)
364 modifyVarEnv_Directly :: (a -> a) -> UniqFM a -> Unique -> UniqFM a
365 modifyVarEnv_Directly mangle_fn env key
366 = case (lookupUFM_Directly env key) of
368 Just xx -> addToUFM_Directly env key (mangle_fn xx)