[project @ 2003-12-16 16:19:29 by simonpj]

[ghc-hetmet.git] / ghc / compiler / basicTypes / NameSet.lhs

diff --git a/ghc/compiler/basicTypes/NameSet.lhs b/ghc/compiler/basicTypes/NameSet.lhs
index 1c9d02b..d0e55de 100644 (file)
--- a/ghc/compiler/basicTypes/NameSet.lhs
+++ b/ghc/compiler/basicTypes/NameSet.lhs
@@ -9,7 +9,17 @@ module NameSet (
        NameSet,
        emptyNameSet, unitNameSet, mkNameSet, unionNameSets, unionManyNameSets,
        minusNameSet, elemNameSet, nameSetToList, addOneToNameSet, addListToNameSet, 
-       delFromNameSet, delListFromNameSet, isEmptyNameSet, foldNameSet
+       delFromNameSet, delListFromNameSet, isEmptyNameSet, foldNameSet, filterNameSet,
+       intersectsNameSet, intersectNameSet,
+       
+       -- Free variables
+       FreeVars, isEmptyFVs, emptyFVs, plusFVs, plusFV, 
+       mkFVs, addOneFV, unitFV, delFV, delFVs,
+
+       -- Defs and uses
+       Defs, Uses, DefUse, DefUses,
+       emptyDUs, usesOnly, mkDUs, plusDU, 
+       findUses, duDefs, duUses, allUses
     ) where
 
 #include "HsVersions.h"
@@ -41,6 +51,10 @@ isEmptyNameSet          :: NameSet -> Bool
 delFromNameSet    :: NameSet -> Name -> NameSet
 delListFromNameSet :: NameSet -> [Name] -> NameSet
 foldNameSet       :: (Name -> b -> b) -> b -> NameSet -> b
+filterNameSet     :: (Name -> Bool) -> NameSet -> NameSet
+intersectNameSet   :: NameSet -> NameSet -> NameSet
+intersectsNameSet  :: NameSet -> NameSet -> Bool       -- True if non-empty intersection
+       -- (s1 `intersectsVarSet` s2) doesn't compute s2 if s1 is empty
 
 isEmptyNameSet    = isEmptyUniqSet
 emptyNameSet     = emptyUniqSet
@@ -55,8 +69,122 @@ elemNameSet       = elementOfUniqSet
 nameSetToList     = uniqSetToList
 delFromNameSet    = delOneFromUniqSet
 foldNameSet      = foldUniqSet
+filterNameSet    = filterUniqSet
+intersectNameSet  = intersectUniqSets
 
 delListFromNameSet set ns = foldl delFromNameSet set ns
+
+intersectsNameSet s1 s2 = not (isEmptyNameSet (s1 `intersectNameSet` s2))
 \end{code}
 
 
+%************************************************************************
+%*                                                                     *
+\subsection{Free variables}
+%*                                                                     *
+%************************************************************************
+
+These synonyms are useful when we are thinking of free variables
+
+\begin{code}
+type FreeVars  = NameSet
+
+plusFV   :: FreeVars -> FreeVars -> FreeVars
+addOneFV :: FreeVars -> Name -> FreeVars
+unitFV   :: Name -> FreeVars
+emptyFVs :: FreeVars
+plusFVs  :: [FreeVars] -> FreeVars
+mkFVs   :: [Name] -> FreeVars
+delFV    :: Name -> FreeVars -> FreeVars
+delFVs   :: [Name] -> FreeVars -> FreeVars
+
+isEmptyFVs  = isEmptyNameSet
+emptyFVs    = emptyNameSet
+plusFVs     = unionManyNameSets
+plusFV      = unionNameSets
+mkFVs      = mkNameSet
+addOneFV    = addOneToNameSet
+unitFV      = unitNameSet
+delFV n s   = delFromNameSet s n
+delFVs ns s = delListFromNameSet s ns
+\end{code}
+
+
+%************************************************************************
+%*                                                                     *
+               Defs and uses
+%*                                                                     *
+%************************************************************************
+
+\begin{code}
+type Defs = NameSet
+type Uses = NameSet
+
+type DefUses = [DefUse]
+       -- In dependency order: earlier Defs scope over later Uses
+
+type DefUse  = (Maybe Defs, Uses)
+       -- For items (Just ds, us), the use of any member 
+       -- of the ds implies that all the us are used too
+       --
+       -- Also, us may mention ds
+       --
+       -- Nothing => Nothing defined in this group, but
+       --            nevertheless all the uses are essential.
+       --            Used for instance declarations, for example
+
+emptyDUs :: DefUses
+emptyDUs = []
+
+usesOnly :: Uses -> DefUses
+usesOnly uses = [(Nothing, uses)]
+
+mkDUs :: [(Defs,Uses)] -> DefUses
+mkDUs pairs = [(Just defs, uses) | (defs,uses) <- pairs]
+
+plusDU :: DefUses -> DefUses -> DefUses
+plusDU = (++)
+
+duDefs :: DefUses -> Defs
+duDefs dus = foldr get emptyNameSet dus
+  where
+    get (Nothing, u1) d2 = d2
+    get (Just d1, u1) d2 = d1 `unionNameSets` d2
+
+duUses :: DefUses -> Uses
+-- Just like allUses, but defs are not eliminated
+duUses dus = foldr get emptyNameSet dus
+  where
+    get (d1, u1) u2 = u1 `unionNameSets` u2
+
+allUses :: DefUses -> Uses
+-- Collect all uses, regardless of
+-- whether the group is itself used,
+-- but remove defs on the way
+allUses dus
+  = foldr get emptyNameSet dus
+  where
+    get (Nothing,   rhs_uses) uses = rhs_uses `unionNameSets` uses
+    get (Just defs, rhs_uses) uses = (rhs_uses `unionNameSets` uses)
+                                    `minusNameSet` defs
+
+findUses :: DefUses -> Uses -> Uses
+-- Given some DefUses and some Uses, 
+-- find all the uses, transitively. 
+-- The result is a superset of the input uses;
+-- and includes things defined in the input DefUses
+-- (but only if they are used)
+findUses dus uses 
+  = foldr get uses dus
+  where
+    get (Nothing, rhs_uses) uses
+       = rhs_uses `unionNameSets` uses
+    get (Just defs, rhs_uses) uses
+       | defs `intersectsNameSet` uses         -- Used
+       || not (all (reportIfUnused . nameOccName) (nameSetToList defs))
+               -- At least one starts with an "_", 
+               -- so treat the group as used
+       = rhs_uses `unionNameSets` uses
+       | otherwise     -- No def is used
+       = uses
+\end{code}
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