add ZDD.fromSetOfIntSets

src/Data/DecisionDiagram/ZDD.hs

@@ -36,6 +36,7 @@ module Data.DecisionDiagram.ZDD
   -- * Construction
   , empty
   , base
+  , fromSetOfIntSets
 
   -- * Query
   , null
@@ -79,6 +80,7 @@ import qualified Data.HashTable.Class as H
 import qualified Data.HashTable.ST.Cuckoo as C
 import Data.IntSet (IntSet)
 import qualified Data.IntSet as IntSet
+import Data.List (sortBy)
 import Data.Proxy
 import Data.Set (Set)
 import qualified Data.Set as Set
@@ -415,6 +417,15 @@ isProperSubsetOf a b = a `isSubsetOf` b && a /= b
 disjoint :: ItemOrder a => ZDD a -> ZDD a -> Bool
 disjoint a b = null (a `intersection` b)
 
+-- | Create a ZDD from a set of 'IntSet'
+fromSetOfIntSets :: forall a. ItemOrder a => Set IntSet -> ZDD a
+fromSetOfIntSets xss = unions
+  [ ZDD $ foldr (\x node -> Branch x F node) T
+        $ sortBy (compareItem (Proxy :: Proxy a))
+        $ IntSet.toList xs
+  | xs <- Set.toList xss
+  ]    
+
 -- | Convert the family to a set of 'IntSet'.
 toSetOfIntSets :: ZDD a -> Set IntSet
 toSetOfIntSets (ZDD node) = runST $ do

test/TestZDD.hs

@@ -280,6 +280,21 @@ prop_base =
   withDefaultOrder $ \(_ :: Proxy o) ->
     ZDD.toSetOfIntSets (ZDD.base :: ZDD o) === Set.singleton IntSet.empty
 
+prop_toSetOfIntSets_fromSetOfIntSets :: Property
+prop_toSetOfIntSets_fromSetOfIntSets =
+  withDefaultOrder $ \(_ :: Proxy o) ->
+    forAll (liftM (Set.fromList . map IntSet.fromList) arbitrary) $ \xss ->
+      let a :: ZDD o
+          a = ZDD.fromSetOfIntSets xss
+       in counterexample (show a) $ ZDD.toSetOfIntSets a === xss
+
+prop_fromSetOfIntSets_toSetOfIntSets :: Property
+prop_fromSetOfIntSets_toSetOfIntSets =
+  withDefaultOrder $ \(_ :: Proxy o) ->
+    forAll arbitrary $ \(a :: ZDD o) ->
+      let xss = ZDD.toSetOfIntSets a
+       in counterexample (show xss) $ ZDD.fromSetOfIntSets xss === a
+
 prop_change :: Property
 prop_change =
   withDefaultOrder $ \(_ :: Proxy o) ->