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1+{-# LANGUAGE FlexibleContexts #-}
2+{-# LANGUAGE LambdaCase #-}
3+{-# LANGUAGE PatternGuards #-}
4+{-# LANGUAGE ScopedTypeVariables #-}
5+{-# LANGUAGE StandaloneDeriving #-}
6+{-# LANGUAGE TypeFamilies #-}
7+{-# LANGUAGE UndecidableInstances #-}
8+-- | 'Patch'es on 'Map' that can insert, delete, and move values from one key to
10+module Reflex.Patch.MapWithMove2 where
12+import Reflex.Patch.Class
15+import Control.Monad.State
20+import qualified Data.Map as Map
23+import qualified Data.Set as Set
27+-- | Patch a DMap with additions, deletions, and moves. Invariant: If key @k1@
28+-- is coming from @From_Move k2@, then key @k2@ should be going to @Just k1@,
29+-- and vice versa. There should never be any unpaired From/To keys.
30+newtype PatchMapWithMove2 k p = PatchMapWithMove2 (Map k (NodeInfo k p))
31+deriving instance (Show k, Show p, Show (PatchTarget p)) => Show (PatchMapWithMove2 k p)
32+deriving instance (Eq k, Eq p, Eq (PatchTarget p)) => Eq (PatchMapWithMove2 k p)
33+deriving instance (Ord k, Ord p, Ord (PatchTarget p)) => Ord (PatchMapWithMove2 k p)
35+-- | Holds the information about each key: where its new value should come from,
36+-- and where its old value should go to
37+data NodeInfo k p = NodeInfo
38+ { _nodeInfo_from :: !(From k p)
39+ -- ^ Where do we get the new value for this key?
40+ , _nodeInfo_to :: !(To k)
41+ -- ^ If the old value is being kept (i.e. moved rather than deleted or
42+ -- replaced), where is it going?
44+deriving instance (Show k, Show p, Show (PatchTarget p)) => Show (NodeInfo k p)
45+deriving instance (Read k, Read p, Read (PatchTarget p)) => Read (NodeInfo k p)
46+deriving instance (Eq k, Eq p, Eq (PatchTarget p)) => Eq (NodeInfo k p)
47+deriving instance (Ord k, Ord p, Ord (PatchTarget p)) => Ord (NodeInfo k p)
49+-- | Create a 'PatchMapWithMove2', validating it
50+patchMapWithMove2 :: Ord k => Map k (NodeInfo k p) -> Maybe (PatchMapWithMove2 k p)
51+patchMapWithMove2 m = if valid then Just $ PatchMapWithMove2 m else Nothing
52+ where valid = forwardLinks == backwardLinks
53+ forwardLinks = Map.mapMaybe _nodeInfo_to m
54+ backwardLinks = Map.fromList $ catMaybes $ flip fmap (Map.toList m) $ \(to, p) ->
55+ case _nodeInfo_from p of
56+ From_Move from _ -> Just (from, to)
59+-- | Create a 'PatchMapWithMove2' that inserts everything in the given 'Map'
60+patchMapWithMove2InsertAll :: Map k (PatchTarget p) -> PatchMapWithMove2 k p
61+patchMapWithMove2InsertAll m = PatchMapWithMove2 $ flip fmap m $ \v -> NodeInfo
62+ { _nodeInfo_from = From_Insert v
63+ , _nodeInfo_to = Nothing
66+-- | Extract the internal representation of the 'PatchMapWithMove2'
67+unPatchMapWithMove2 :: PatchMapWithMove2 k p -> Map k (NodeInfo k p)
68+unPatchMapWithMove2 (PatchMapWithMove2 p) = p
70+-- | Warning: when using this function, you must ensure that the invariants of
71+-- 'PatchMapWithMove2' are preserved; they will not be checked.
72+unsafePatchMapWithMove2 :: Map k (NodeInfo k p) -> PatchMapWithMove2 k p
73+unsafePatchMapWithMove2 = PatchMapWithMove2
75+-- | Describe how a key's new value should be produced
77+ = From_Insert (PatchTarget p) -- ^ Insert the given value here
78+ | From_Delete -- ^ Delete the existing value, if any, from here
79+ | From_Move !k !p -- ^ Move the value here from the given key, and apply the given patch
81+deriving instance (Show k, Show p, Show (PatchTarget p)) => Show (From k p)
82+deriving instance (Read k, Read p, Read (PatchTarget p)) => Read (From k p)
83+deriving instance (Eq k, Eq p, Eq (PatchTarget p)) => Eq (From k p)
84+deriving instance (Ord k, Ord p, Ord (PatchTarget p)) => Ord (From k p)
86+-- | Describe where a key's old value will go. If this is 'Just', that means
87+-- the key's old value will be moved to the given other key; if it is 'Nothing',
88+-- that means it will be deleted.
91+-- | Apply the insertions, deletions, and moves to a given 'Map'
92+instance (Ord k, Patch p) => Patch (PatchMapWithMove2 k p) where
93+ type PatchTarget (PatchMapWithMove2 k p) = Map k (PatchTarget p)
94+ apply (PatchMapWithMove2 m) old = Just $! insertions `Map.union` (old `Map.difference` deletions) --TODO: return Nothing sometimes --Note: the strict application here is critical to ensuring that incremental merges don't hold onto all their prerequisite events forever; can we make this more robust?
95+ where insertions = flip Map.mapMaybeWithKey m $ \_ ni -> case _nodeInfo_from ni of
96+ From_Insert v -> Just v
97+ From_Move k p -> applyAlways p <$> Map.lookup k old
98+ From_Delete -> Nothing
99+ deletions = flip Map.mapMaybeWithKey m $ \_ ni -> case _nodeInfo_from ni of
100+ From_Delete -> Just ()
103+-- | Returns all the new elements that will be added to the 'Map'
104+patchMapWithMove2NewElements :: PatchMapWithMove2 k p -> [PatchTarget p]
105+patchMapWithMove2NewElements = Map.elems . patchMapWithMove2NewElementsMap
107+patchMapWithMove2NewElementsMap :: PatchMapWithMove2 k p -> Map k (PatchTarget p)
108+patchMapWithMove2NewElementsMap (PatchMapWithMove2 p) = Map.mapMaybe f p
109+ where f ni = case _nodeInfo_from ni of
110+ From_Insert v -> Just v
111+ From_Move _ _ -> Nothing
112+ From_Delete -> Nothing
114+-- | Create a 'PatchMapWithMove2' that, if applied to the given 'Map', will sort
115+-- its values using the given ordering function. The set keys of the 'Map' is
117+patchThatSortsMapWith :: (Ord k, Monoid p) => (PatchTarget p -> PatchTarget p -> Ordering) -> Map k (PatchTarget p) -> PatchMapWithMove2 k p
118+patchThatSortsMapWith cmp m = PatchMapWithMove2 $ Map.fromList $ catMaybes $ zipWith g unsorted sorted
119+ where unsorted = Map.toList m
120+ sorted = sortBy (cmp `on` snd) unsorted
121+ f (to, _) (from, _) = if to == from then Nothing else
123+ reverseMapping = Map.fromList $ catMaybes $ zipWith f unsorted sorted
124+ g (to, _) (from, _) = if to == from then Nothing else
125+ let Just movingTo = Map.lookup from reverseMapping
126+ in Just (to, NodeInfo (From_Move from mempty) $ Just movingTo)
128+-- | Create a 'PatchMapWithMove2' that, if applied to the first 'Map' provided,
129+-- will produce a 'Map' with the same values as the second 'Map' but with the
130+-- values sorted with the given ordering function.
131+patchThatChangesAndSortsMapWith :: forall k p. (Ord k, Ord (PatchTarget p), Monoid p) => (PatchTarget p -> PatchTarget p -> Ordering) -> Map k (PatchTarget p) -> Map k (PatchTarget p) -> PatchMapWithMove2 k p
132+patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatChangesMap oldByIndex newByIndex
133+ where newList = Map.toList newByIndexUnsorted
134+ newByIndex = Map.fromList $ zip (fst <$> newList) $ sortBy cmp $ snd <$> newList
136+-- | Create a 'PatchMapWithMove2' that, if applied to the first 'Map' provided,
137+-- will produce the second 'Map'.
138+patchThatChangesMap :: (Ord k, Ord (PatchTarget p), Monoid p) => Map k (PatchTarget p) -> Map k (PatchTarget p) -> PatchMapWithMove2 k p
139+patchThatChangesMap oldByIndex newByIndex = patch
140+ where oldByValue = Map.fromListWith Set.union $ swap . first Set.singleton <$> Map.toList oldByIndex
141+ (insertsAndMoves, unusedValuesByValue) = flip runState oldByValue $ do
143+ remainingValues <- get
144+ let putRemainingKeys remainingKeys = put $ if Set.null remainingKeys
145+ then Map.delete v remainingValues
146+ else Map.insert v remainingKeys remainingValues
147+ case Map.lookup v remainingValues of
148+ Nothing -> return $ NodeInfo (From_Insert v) $ Just undefined -- There's no existing value we can take
150+ if k `Set.member` fromKs
152+ putRemainingKeys $ Set.delete k fromKs
153+ return $ NodeInfo (From_Move k mempty) $ Just undefined -- There's an existing value, and it's here, so no patch necessary
155+ (fromK, remainingKeys) <- return . fromJust $ Set.minView fromKs -- There's an existing value, but it's not here; move it here
156+ putRemainingKeys remainingKeys
157+ return $ NodeInfo (From_Move fromK mempty) $ Just undefined
158+ Map.traverseWithKey f newByIndex
159+ unusedOldKeys = fold unusedValuesByValue
160+ pointlessMove k = \case
161+ From_Move k' _ | k == k' -> True
163+ keyWasMoved k = if k `Map.member` oldByIndex && not (k `Set.member` unusedOldKeys)
166+ patch = unsafePatchMapWithMove2 $ Map.filterWithKey (\k -> not . pointlessMove k . _nodeInfo_from) $ Map.mergeWithKey (\k a _ -> Just $ nodeInfoSetTo (keyWasMoved k) a) (Map.mapWithKey $ \k -> nodeInfoSetTo $ keyWasMoved k) (Map.mapWithKey $ \k _ -> NodeInfo From_Delete $ keyWasMoved k) insertsAndMoves oldByIndex
168+-- | Change the 'From' value of a 'NodeInfo'
169+nodeInfoMapFrom :: (From k v -> From k v) -> NodeInfo k v -> NodeInfo k v
170+nodeInfoMapFrom f ni = ni { _nodeInfo_from = f $ _nodeInfo_from ni }
172+-- | Change the 'From' value of a 'NodeInfo', using a 'Functor' (or
173+-- 'Applicative', 'Monad', etc.) action to get the new value
174+nodeInfoMapMFrom :: Functor f => (From k v -> f (From k v)) -> NodeInfo k v -> f (NodeInfo k v)
175+nodeInfoMapMFrom f ni = fmap (\result -> ni { _nodeInfo_from = result }) $ f $ _nodeInfo_from ni
177+-- | Set the 'To' field of a 'NodeInfo'
178+nodeInfoSetTo :: To k -> NodeInfo k v -> NodeInfo k v
179+nodeInfoSetTo to ni = ni { _nodeInfo_to = to }
181+-- |Helper data structure used for composing patches using the monoid instance.
184+ | Fixup_Update (These (From k v) (To k))
186+-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
187+instance (Ord k, Monoid p, Eq p, Patch p) => Semigroup (PatchMapWithMove2 k p) where
188+ PatchMapWithMove2 ma <> PatchMapWithMove2 mb = PatchMapWithMove2 m
190+ connections = Map.toList $ Map.intersectionWithKey (\_ a b -> (_nodeInfo_to a, _nodeInfo_from b)) ma mb
191+ h :: (k, (Maybe k, From k p)) -> [(k, Fixup k p)]
192+ h (_, (mToAfter, editBefore)) = case (mToAfter, editBefore) of
193+ (Just toAfter, From_Move fromBefore p)
194+ | fromBefore == toAfter && p == mempty
195+ -> [(toAfter, Fixup_Delete)]
197+ -> [ (toAfter, Fixup_Update (This editBefore))
198+ , (fromBefore, Fixup_Update (That mToAfter))
200+ (Nothing, From_Move fromBefore _) -> [(fromBefore, Fixup_Update (That mToAfter))] -- The item is destroyed in the second patch, so indicate that it is destroyed in the source map
201+ (Just toAfter, _) -> [(toAfter, Fixup_Update (This editBefore))]
203+ mergeFixups _ Fixup_Delete Fixup_Delete = Fixup_Delete
204+ mergeFixups _ (Fixup_Update a) (Fixup_Update b)
205+ | This x <- a, That y <- b
206+ = Fixup_Update $ These x y
207+ | That y <- a, This x <- b
208+ = Fixup_Update $ These x y
209+ mergeFixups _ _ _ = error "PatchMapWithMove2: incompatible fixups"
210+ fixups = Map.fromListWithKey mergeFixups $ concatMap h connections
211+ combineNodeInfos _ nia nib = NodeInfo
212+ { _nodeInfo_from = _nodeInfo_from nia
213+ , _nodeInfo_to = _nodeInfo_to nib
215+ applyFixup _ ni = \case
216+ Fixup_Delete -> Nothing
217+ Fixup_Update u -> Just $ NodeInfo
218+ { _nodeInfo_from = case _nodeInfo_from ni of
219+ f@(From_Move _ p') -> case getHere u of -- The `from` fixup comes from the "old" patch
220+ Nothing -> f -- If there's no `from` fixup, just use the "new" `from`
221+ Just (From_Insert v) -> From_Insert $ applyAlways p' v
222+ Just From_Delete -> From_Delete
223+ Just (From_Move oldKey p) -> From_Move oldKey $ p' <> p
224+ _ -> error "PatchMapWithMove2: fixup for non-move From"
225+ , _nodeInfo_to = fromMaybe (_nodeInfo_to ni) $ getThere u
227+ m = Map.differenceWithKey applyFixup (Map.unionWithKey combineNodeInfos ma mb) fixups
228+ getHere :: These a b -> Maybe a
233+ getThere :: These a b -> Maybe b
239+--TODO: Figure out how to implement this in terms of PatchDMapWithMove rather than duplicating it here
240+-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
241+instance (Ord k, Monoid p, Eq p, Patch p) => Monoid (PatchMapWithMove2 k p) where
242+ mempty = PatchMapWithMove2 mempty