deleting RingMap entries, list conversion

src/Hash2Pub/FediChordTypes.hs

@@ -23,6 +23,9 @@ module Hash2Pub.FediChordTypes (
   , addRMapEntryWith
   , takeRMapPredecessors
   , takeRMapSuccessors
+  , deleteRMapEntry
+                               , rMapFromList
+                               , rMapToList
   , cacheGetNodeStateUnvalidated
   , initCache
   , cacheEntries
@@ -288,14 +291,15 @@ instance Enum ProxyDirection where
     fromEnum Backwards = - 1
     fromEnum Forwards  = 1
 
+-- | helper function for getting the a from a RingEntry a
+extractRingEntry :: HasKeyID a => RingEntry a -> Maybe a
+extractRingEntry (KeyEntry entry)                       = Just entry
+extractRingEntry (ProxyEntry _ (Just (KeyEntry entry))) = Just entry
+extractRingEntry _                                      = Nothing
+
 --- useful function for getting entries for a full cache transfer
 cacheEntries :: NodeCache -> [CacheEntry]
-cacheEntries = mapMaybe extractNodeEntries . Map.elems . getRingMap
-    where
-  extractNodeEntries :: RingEntry CacheEntry  -> Maybe CacheEntry
-  extractNodeEntries (ProxyEntry _ (Just (KeyEntry entry))) = Just entry
-  extractNodeEntries (KeyEntry entry)                       = Just entry
-  extractNodeEntries _                                      = Nothing
+cacheEntries = mapMaybe extractRingEntry . Map.elems . getRingMap
 
 -- | An empty 'RingMap' needs to be initialised with 2 proxy entries,
 -- linking the modular name space together by connecting @minBound@ and @maxBound@
@@ -312,10 +316,7 @@ rMapLookup :: HasKeyID a
            => NodeID       -- ^lookup key
            -> RingMap a    -- ^lookup cache
            -> Maybe a
-rMapLookup key rmap = case Map.lookup key $ getRingMap rmap of
-                          Just (ProxyEntry _ (Just (KeyEntry result))) -> Just result
-                          Just (KeyEntry res)                        -> Just res
-                          _     -> Nothing
+rMapLookup key rmap =  extractRingEntry =<< Map.lookup key (getRingMap rmap)
 
 cacheLookup :: NodeID       -- ^lookup key
             -> NodeCache    -- ^lookup cache
@@ -425,6 +426,21 @@ setRMapEntries :: (Foldable t, HasKeyID a)
                -> RingMap a
 setRMapEntries entries = addRMapEntries entries emptyRMap
 
+deleteRMapEntry :: (HasKeyID a)
+                => NodeID
+                -> RingMap a
+                -> RingMap a
+deleteRMapEntry nid = RingMap . Map.update modifier nid . getRingMap
+  where
+    modifier (ProxyEntry idPointer _) = Just (ProxyEntry idPointer Nothing)
+    modifier KeyEntry {}              = Nothing
+
+rMapToList :: (HasKeyID a) => RingMap a -> [a]
+rMapToList = mapMaybe extractRingEntry . Map.elems . getRingMap
+
+rMapFromList :: (HasKeyID a) => [a] -> RingMap a
+rMapFromList = setRMapEntries
+
 -- | takes up to i entries from a 'RingMap' by calling a getter function on a
 -- *startAt* value and after that on the previously returned value.
 -- Stops once i entries have been taken or an entry has been encountered twice