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Refactor 'Explore.backjumpInfo' after code review #3209

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merged 1 commit into from
Mar 5, 2016
Merged

Refactor 'Explore.backjumpInfo' after code review #3209

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16 changes: 5 additions & 11 deletions cabal-install/Distribution/Client/Dependency/Modular/Explore.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -32,17 +32,20 @@ import qualified Distribution.Client.Dependency.Types as T
-- return it immediately. If all children contain conflict sets, we can
-- take the union as the combined conflict set.
backjump :: F.Foldable t => Var QPN -> t (ConflictSetLog a) -> ConflictSetLog a
backjump var xs = F.foldr combine backjumpInfo xs S.empty
backjump var xs = F.foldr combine logBackjump xs S.empty
where
combine :: ConflictSetLog a
-> (ConflictSet QPN -> ConflictSetLog a)
-> ConflictSet QPN -> ConflictSetLog a
combine (T.Done x) _ _ = T.Done x
combine (T.Fail cs) f csAcc
| not (simplifyVar var `S.member` cs) = backjumpInfo cs
| not (simplifyVar var `S.member` cs) = logBackjump cs
| otherwise = f (csAcc `S.union` cs)
combine (T.Step m ms) f cs = T.Step m (combine ms f cs)

logBackjump :: ConflictSet QPN -> ConflictSetLog a
logBackjump cs = failWith (Failure cs Backjump) cs

type ConflictSetLog = T.Progress Message (ConflictSet QPN)

-- | A tree traversal that simultaneously propagates conflict sets up
Expand Down Expand Up @@ -77,15 +80,6 @@ exploreLog = cata go
(failWith (Failure S.empty EmptyGoalChoice) S.empty) -- empty goal choice is an internal error
(\ k v _xs -> continueWith (Next (close k)) (v a)) -- commit to the first goal choice

-- | Add in information about pruned trees.
--
-- TODO: This isn't quite optimal, because we do not merely report the shape of the
-- tree, but rather make assumptions about where that shape originated from. It'd be
-- better if the pruning itself would leave information that we could pick up at this
-- point.
backjumpInfo :: ConflictSet QPN -> ConflictSetLog a
backjumpInfo cs = failWith (Failure cs Backjump) cs

-- | Interface.
backjumpAndExplore :: Tree a -> Log Message (Assignment, RevDepMap)
backjumpAndExplore t = toLog $ exploreLog t (A M.empty M.empty M.empty)
Expand Down