-- ** Manipulating these environments
emptyVarEnv, unitVarEnv, mkVarEnv,
elemVarEnv, varEnvElts, varEnvKeys,
- extendVarEnv, extendVarEnv_C, extendVarEnvList,
+ extendVarEnv, extendVarEnv_C, extendVarEnv_Acc, extendVarEnvList,
plusVarEnv, plusVarEnv_C,
delVarEnvList, delVarEnv,
lookupVarEnv, lookupVarEnv_NF, lookupWithDefaultVarEnv,
modifyVarEnv, modifyVarEnv_Directly,
isEmptyVarEnv, foldVarEnv,
elemVarEnvByKey, lookupVarEnv_Directly,
- filterVarEnv_Directly,
+ filterVarEnv_Directly, restrictVarEnv,
-- * The InScopeSet type
InScopeSet,
-- ** Operations on InScopeSets
emptyInScopeSet, mkInScopeSet, delInScopeSet,
extendInScopeSet, extendInScopeSetList, extendInScopeSetSet,
- modifyInScopeSet,
getInScopeVars, lookupInScope, elemInScopeSet, uniqAway,
-- * The RnEnv2 type
\begin{code}
-- | A set of variables that are in scope at some point
data InScopeSet = InScope (VarEnv Var) FastInt
- -- The Int# is a kind of hash-value used by uniqAway
+ -- The (VarEnv Var) is just a VarSet. But we write it like
+ -- this to remind ourselves that you can look up a Var in
+ -- the InScopeSet. Typically the InScopeSet contains the
+ -- canonical version of the variable (e.g. with an informative
+ -- unfolding), so this lookup is useful.
+ --
+ -- INVARIANT: the VarEnv maps (the Unique of) a variable to
+ -- a variable with the same Uniqua. (This was not
+ -- the case in the past, when we had a grevious hack
+ -- mapping var1 to var2.
+ --
+ -- The FastInt is a kind of hash-value used by uniqAway
-- For example, it might be the size of the set
-- INVARIANT: it's not zero; we use it as a multiplier in uniqAway
extendInScopeSetSet (InScope in_scope n) vs
= InScope (in_scope `plusVarEnv` vs) (n +# iUnbox (sizeUFM vs))
--- | Replace the first 'Var' with the second in the set of in-scope variables
-modifyInScopeSet :: InScopeSet -> Var -> Var -> InScopeSet
--- Exploit the fact that the in-scope "set" is really a map
--- Make old_v map to new_v
--- QUESTION: shouldn't we add a mapping from new_v to new_v as it is presumably now in scope? - MB 08
-modifyInScopeSet (InScope in_scope n) old_v new_v = InScope (extendVarEnv in_scope old_v new_v) (n +# _ILIT(1))
-
delInScopeSet :: InScopeSet -> Var -> InScopeSet
delInScopeSet (InScope in_scope n) v = InScope (in_scope `delVarEnv` v) n
elemInScopeSet :: Var -> InScopeSet -> Bool
elemInScopeSet v (InScope in_scope _) = v `elemVarEnv` in_scope
--- | If the given variable was even added to the 'InScopeSet', or if it was the \"from\" argument
--- of any 'modifyInScopeSet' operation, returns that variable with all appropriate modifications
--- applied to it. Otherwise, return @Nothing@
+-- | Look up a variable the 'InScopeSet'. This lets you map from
+-- the variable's identity (unique) to its full value.
lookupInScope :: InScopeSet -> Var -> Maybe Var
--- It's important to look for a fixed point
--- When we see (case x of y { I# v -> ... })
--- we add [x -> y] to the in-scope set (Simplify.simplCaseBinder and
--- modifyInScopeSet).
---
--- When we lookup up an occurrence of x, we map to y, but then
--- we want to look up y in case it has acquired more evaluation information by now.
-lookupInScope (InScope in_scope _) v
- = go v
- where
- go v = case lookupVarEnv in_scope v of
- Just v' | v == v' -> Just v' -- Reached a fixed point
- | otherwise -> go v'
- Nothing -> Nothing
+lookupInScope (InScope in_scope _) v = lookupVarEnv in_scope v
\end{code}
\begin{code}
unitVarEnv :: Var -> a -> VarEnv a
extendVarEnv :: VarEnv a -> Var -> a -> VarEnv a
extendVarEnv_C :: (a->a->a) -> VarEnv a -> Var -> a -> VarEnv a
+extendVarEnv_Acc :: (a->b->b) -> (a->b) -> VarEnv b -> Var -> a -> VarEnv b
plusVarEnv :: VarEnv a -> VarEnv a -> VarEnv a
extendVarEnvList :: VarEnv a -> [(Var, a)] -> VarEnv a
lookupVarEnv_Directly :: VarEnv a -> Unique -> Maybe a
filterVarEnv_Directly :: (Unique -> a -> Bool) -> VarEnv a -> VarEnv a
+restrictVarEnv :: VarEnv a -> VarSet -> VarEnv a
delVarEnvList :: VarEnv a -> [Var] -> VarEnv a
delVarEnv :: VarEnv a -> Var -> VarEnv a
plusVarEnv_C :: (a -> a -> a) -> VarEnv a -> VarEnv a -> VarEnv a
elemVarEnvByKey = elemUFM_Directly
extendVarEnv = addToUFM
extendVarEnv_C = addToUFM_C
+extendVarEnv_Acc = addToUFM_Acc
extendVarEnvList = addListToUFM
plusVarEnv_C = plusUFM_C
delVarEnvList = delListFromUFM
lookupVarEnv_Directly = lookupUFM_Directly
filterVarEnv_Directly = filterUFM_Directly
+restrictVarEnv env vs = filterVarEnv_Directly keep env
+ where
+ keep u _ = u `elemVarSetByKey` vs
+
zipVarEnv tyvars tys = mkVarEnv (zipEqual "zipVarEnv" tyvars tys)
lookupVarEnv_NF env id = case lookupVarEnv env id of
Just xx -> xx