-- Free variables
FreeVars, isEmptyFVs, emptyFVs, plusFVs, plusFV,
- mkFVs, addOneFV, unitFV, delFV, delFVs
+ mkFVs, addOneFV, unitFV, delFV, delFVs,
+
+ -- Defs and uses
+ Defs, Uses, DefUse, DefUses,
+ emptyDUs, usesOnly, mkDUs, plusDU,
+ findUses, duDefs, duUses, allUses
) where
#include "HsVersions.h"
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}
\ No newline at end of file