findAdded masterstate childstate $ lastchildstate)
++ (map (pairToFunc ModifyContent) . Map.toList $ childPayloadChanges)
masterPayloadChanges =
- (Map.filterWithKey filterKV
- (Map.intersection
- (Map.union (findModified childstate lastchildstate)
- (findModified childstate masterstate)
- )
- masterstate
- )
- )
- where filterKV k v = -- Eliminate changes that would set the value to what it already is
- case Map.lookup k masterstate of
- (Just m) -> m /= v
- Nothing -> False
+ Map.union (findModified masterstate childstate lastchildstate)
+ (findModified masterstate childstate masterstate)
-- The child's payload takes precedence, so we are going to
-- calculate the changes made on the master to apply to the client,
-- then subtract out any items in the master changes that have the
-- same key.
childPayloadChanges =
- Map.intersection
- (Map.difference (findModified masterstate lastchildstate)
- (findModified childstate lastchildstate))
- childstate
+ foldl (\m (k, v) -> Map.adjust (\_ -> v) k m)
+ (findModified childstate masterstate lastchildstate)
+ (Map.toList $ findModified masterstate childstate lastchildstate)
{- | Compares two SyncCollections, and returns the commands that, when
applied to the first collection, would yield the second. -}
is different in state1 than it was in lastchildstate. Returns the key and new
payload for each such item found. -}
findModified :: (Ord k, Eq v) =>
- SyncCollection k v -> SyncCollection k v -> SyncCollection k v
-findModified state1 lastchildstate =
+ SyncCollection k v -> SyncCollection k v -> SyncCollection k v -> SyncCollection k v
+findModified basestate state1 lastchildstate =
Map.mapMaybe id .
- Map.intersectionWith (\v1 v2 -> if v1 /= v2 then Just v1 else Nothing)
- state1 $ lastchildstate
+ Map.intersectionWithKey comparefunc state1 $ lastchildstate
+ where comparefunc k v1 v2 =
+ if v1 /= v2
+ then case Map.lookup k basestate of
+ Nothing -> Nothing
+ Just baseval ->
+ if baseval == v1
+ then Nothing
+ else Just v1
+ else Nothing
{- | Apply the specified changes to the given SyncCollection. Returns
a new SyncCollection with the changes applied. If changes are specified