@@ -1,246 +1,312 @@
11{-# LANGUAGE CPP #-}
2+{-# LANGUAGE DeriveTraversable #-}
23{-# LANGUAGE FlexibleContexts #-}
4+{-# LANGUAGE FlexibleInstances #-}
5+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
36{-# LANGUAGE LambdaCase #-}
7+{-# LANGUAGE MultiParamTypeClasses #-}
48{-# LANGUAGE PatternGuards #-}
9+{-# LANGUAGE PatternSynonyms #-}
510{-# LANGUAGE ScopedTypeVariables #-}
611{-# LANGUAGE StandaloneDeriving #-}
12+{-# LANGUAGE TemplateHaskell #-}
13+{-# LANGUAGE TypeApplications #-}
714{-# LANGUAGE TypeFamilies #-}
8−{-# LANGUAGE UndecidableInstances #-}
15+{-# LANGUAGE ViewPatterns #-}
16+
917-- | 'Patch'es on 'Map' that can insert, delete, and move values from one key to
1018-- another
11−module Data.Patch.MapWithMove where
19+module Data.Patch.MapWithMove
20+ ( PatchMapWithMove
21+ ( PatchMapWithMove
22+ , unPatchMapWithMove
23+ , ..
24+ )
25+ , patchMapWithMove
26+ , patchMapWithMoveInsertAll
27+ , insertMapKey
28+ , moveMapKey
29+ , swapMapKey
30+ , deleteMapKey
31+ , unsafePatchMapWithMove
32+ , patchMapWithMoveNewElements
33+ , patchMapWithMoveNewElementsMap
34+ , patchThatSortsMapWith
35+ , patchThatChangesAndSortsMapWith
36+ , patchThatChangesMap
37+
38+ -- * Node Info
39+ , NodeInfo
40+ ( NodeInfo
41+ , _nodeInfo_to
42+ , _nodeInfo_from
43+ , ..
44+ )
45+ , bitraverseNodeInfo
46+ , nodeInfoMapFrom
47+ , nodeInfoMapMFrom
48+ , nodeInfoSetTo
49+
50+ -- * From
51+ , From
52+ ( From_Insert
53+ , From_Delete
54+ , From_Move
55+ , ..
56+ )
57+ , bitraverseFrom
1258
59+ -- * To
60+ , To
61+ ) where
62+
63+import Data.Coerce
64+import Data.Kind (Type)
1365import Data.Patch.Class
66+import Data.Patch.MapWithPatchingMove (PatchMapWithPatchingMove(..), To)
67+import qualified Data.Patch.MapWithPatchingMove as PM -- already a transparent synonym
1468
15−import Control.Arrow
16−import Control.Monad.Trans.State
17−import Data.Foldable
18−import Data.Function
69+import Control.Lens
1970import Data.List
2071import Data.Map (Map)
2172import qualified Data.Map as Map
22−import Data.Maybe
23−#if !MIN_VERSION_base(4,9,0)
24−import Data.Semigroup
73+import Data.Proxy
74+#if !MIN_VERSION_base(4,11,0)
75+import Data.Semigroup (Semigroup (..))
2576#endif
26−import qualified Data.Set as Set
27−import Data.These
28−import Data.Tuple
77+import Data.Traversable (foldMapDefault)
2978
3079-- | Patch a Map with additions, deletions, and moves. Invariant: If key @k1@
3180-- is coming from @From_Move k2@, then key @k2@ should be going to @Just k1@,
3281-- and vice versa. There should never be any unpaired From/To keys.
33−newtype PatchMapWithMove k p = PatchMapWithMove (Map k (NodeInfo k p))
34−deriving instance (Show k, Show p, Show (PatchTarget p)) => Show (PatchMapWithMove k p)
35−deriving instance (Eq k, Eq p, Eq (PatchTarget p)) => Eq (PatchMapWithMove k p)
36−deriving instance (Ord k, Ord p, Ord (PatchTarget p)) => Ord (PatchMapWithMove k p)
37−
38−-- | Holds the information about each key: where its new value should come from,
39−-- and where its old value should go to
40−data NodeInfo k p = NodeInfo
41− { _nodeInfo_from :: !(From k p)
42− -- ^ Where do we get the new value for this key?
43− , _nodeInfo_to :: !(To k)
44− -- ^ If the old value is being kept (i.e. moved rather than deleted or
45− -- replaced), where is it going?
82+newtype PatchMapWithMove k (v :: Type) = PatchMapWithMove'
83+ { -- | Extract the underlying 'PatchMapWithPatchingMove k (Proxy v)'
84+ unPatchMapWithMove' :: PatchMapWithPatchingMove k (Proxy v)
4685 }
47−deriving instance (Show k, Show p, Show (PatchTarget p)) => Show (NodeInfo k p)
48−deriving instance (Read k, Read p, Read (PatchTarget p)) => Read (NodeInfo k p)
49−deriving instance (Eq k, Eq p, Eq (PatchTarget p)) => Eq (NodeInfo k p)
50−deriving instance (Ord k, Ord p, Ord (PatchTarget p)) => Ord (NodeInfo k p)
86+ deriving ( Show, Read, Eq, Ord
87+-- Haddock cannot handle documentation here before GHC 8.6
88+ ,
89+#if __GLASGOW_HASKELL__ >= 806
90+ -- | Compose patches having the same effect as applying the
91+ -- patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p .
92+ -- 'applyAlways' q@
93+#endif
94+ Semigroup
95+ , Monoid
96+ )
97+
98+pattern Coerce :: Coercible a b => a -> b
99+pattern Coerce x <- (coerce -> x)
100+ where Coerce x = coerce x
101+
102+{-# COMPLETE PatchMapWithMove #-}
103+pattern PatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
104+-- | Extract the representation of the 'PatchMapWithMove' as a map of
105+-- 'NodeInfo'.
106+unPatchMapWithMove :: PatchMapWithMove k v -> Map k (NodeInfo k v)
107+pattern PatchMapWithMove { unPatchMapWithMove } = PatchMapWithMove' (PatchMapWithPatchingMove (Coerce unPatchMapWithMove))
108+
109+_PatchMapWithMove
110+ :: Iso
111+ (PatchMapWithMove k0 v0)
112+ (PatchMapWithMove k1 v1)
113+ (Map k0 (NodeInfo k0 v0))
114+ (Map k1 (NodeInfo k1 v1))
115+_PatchMapWithMove = iso unPatchMapWithMove PatchMapWithMove
116+
117+instance Functor (PatchMapWithMove k) where
118+ fmap f = runIdentity . traverse (Identity . f)
119+
120+instance Foldable (PatchMapWithMove k) where
121+ foldMap = foldMapDefault
122+
123+instance Traversable (PatchMapWithMove k) where
124+ traverse =
125+ _PatchMapWithMove .
126+ traverse .
127+ traverse
128+
129+instance FunctorWithIndex k (PatchMapWithMove k)
130+instance FoldableWithIndex k (PatchMapWithMove k)
131+instance TraversableWithIndex k (PatchMapWithMove k) where
132+ itraverse = itraversed . Indexed
133+ itraversed =
134+ _PatchMapWithMove .>
135+ itraversed <.
136+ traverse
51137
52138-- | Create a 'PatchMapWithMove', validating it
53−patchMapWithMove :: Ord k => Map k (NodeInfo k p) -> Maybe (PatchMapWithMove k p)
54−patchMapWithMove m = if valid then Just $ PatchMapWithMove m else Nothing
55− where valid = forwardLinks == backwardLinks
56− forwardLinks = Map.mapMaybe _nodeInfo_to m
57− backwardLinks = Map.fromList $ catMaybes $ flip fmap (Map.toList m) $ \(to, p) ->
58− case _nodeInfo_from p of
59− From_Move from _ -> Just (from, to)
60− _ -> Nothing
139+patchMapWithMove :: Ord k => Map k (NodeInfo k v) -> Maybe (PatchMapWithMove k v)
140+patchMapWithMove = fmap PatchMapWithMove' . PM.patchMapWithPatchingMove . coerce
61141
62142-- | Create a 'PatchMapWithMove' that inserts everything in the given 'Map'
63−patchMapWithMoveInsertAll :: Map k (PatchTarget p) -> PatchMapWithMove k p
64−patchMapWithMoveInsertAll m = PatchMapWithMove $ flip fmap m $ \v -> NodeInfo
65− { _nodeInfo_from = From_Insert v
66− , _nodeInfo_to = Nothing
67− }
143+patchMapWithMoveInsertAll :: Map k v -> PatchMapWithMove k v
144+patchMapWithMoveInsertAll = PatchMapWithMove' . PM.patchMapWithPatchingMoveInsertAll
68145
69−-- | Extract the internal representation of the 'PatchMapWithMove'
70−unPatchMapWithMove :: PatchMapWithMove k p -> Map k (NodeInfo k p)
71−unPatchMapWithMove (PatchMapWithMove p) = p
146+-- | Make a @'PatchMapWithMove' k v@ which has the effect of inserting or updating a value @v@ to the given key @k@, like 'Map.insert'.
147+insertMapKey :: k -> v -> PatchMapWithMove k v
148+insertMapKey k v = PatchMapWithMove' $ PM.insertMapKey k v
72149
73−-- | Warning: when using this function, you must ensure that the invariants of
74−-- 'PatchMapWithMove' are preserved; they will not be checked.
75−unsafePatchMapWithMove :: Map k (NodeInfo k p) -> PatchMapWithMove k p
76−unsafePatchMapWithMove = PatchMapWithMove
150+-- |Make a @'PatchMapWithMove' k v@ which has the effect of moving the value from the first key @k@ to the second key @k@, equivalent to:
151+--
152+-- @
153+-- 'Map.delete' src (maybe map ('Map.insert' dst) (Map.lookup src map))
154+-- @
155+moveMapKey :: Ord k => k -> k -> PatchMapWithMove k v
156+moveMapKey src dst = PatchMapWithMove' $ PM.moveMapKey src dst
77157
78−-- | Describe how a key's new value should be produced
79−data From k p
80− = From_Insert (PatchTarget p) -- ^ Insert the given value here
81− | From_Delete -- ^ Delete the existing value, if any, from here
82− | From_Move !k !p -- ^ Move the value here from the given key, and apply the given patch
158+-- |Make a @'PatchMapWithMove' k v@ which has the effect of swapping two keys in the mapping, equivalent to:
159+--
160+-- @
161+-- let aMay = Map.lookup a map
162+-- bMay = Map.lookup b map
163+-- in maybe id (Map.insert a) (bMay <> aMay)
164+-- . maybe id (Map.insert b) (aMay <> bMay)
165+-- . Map.delete a . Map.delete b $ map
166+-- @
167+swapMapKey :: Ord k => k -> k -> PatchMapWithMove k v
168+swapMapKey src dst = PatchMapWithMove' $ PM.swapMapKey src dst
83169
84−deriving instance (Show k, Show p, Show (PatchTarget p)) => Show (From k p)
85−deriving instance (Read k, Read p, Read (PatchTarget p)) => Read (From k p)
86−deriving instance (Eq k, Eq p, Eq (PatchTarget p)) => Eq (From k p)
87−deriving instance (Ord k, Ord p, Ord (PatchTarget p)) => Ord (From k p)
170+-- |Make a @'PatchMapWithMove' k v@ which has the effect of deleting a key in the mapping, equivalent to 'Map.delete'.
171+deleteMapKey :: k -> PatchMapWithMove k v
172+deleteMapKey = PatchMapWithMove' . PM.deleteMapKey
88173
89−-- | Describe where a key's old value will go. If this is 'Just', that means
90−-- the key's old value will be moved to the given other key; if it is 'Nothing',
91−-- that means it will be deleted.
92−type To = Maybe
174+-- | Wrap a @'Map' k (NodeInfo k v)@ representing patch changes into a @'PatchMapWithMove' k v@, without checking any invariants.
175+--
176+-- __Warning:__ when using this function, you must ensure that the invariants of 'PatchMapWithMove' are preserved; they will not be checked.
177+unsafePatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
178+unsafePatchMapWithMove = coerce PM.unsafePatchMapWithPatchingMove
93179
94180-- | Apply the insertions, deletions, and moves to a given 'Map'
95−instance (Ord k, Patch p) => Patch (PatchMapWithMove k p) where
96− type PatchTarget (PatchMapWithMove k p) = Map k (PatchTarget p)
97− apply (PatchMapWithMove 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?
98− where insertions = flip Map.mapMaybeWithKey m $ \_ ni -> case _nodeInfo_from ni of
99− From_Insert v -> Just v
100− From_Move k p -> applyAlways p <$> Map.lookup k old
101− From_Delete -> Nothing
102− deletions = flip Map.mapMaybeWithKey m $ \_ ni -> case _nodeInfo_from ni of
103− From_Delete -> Just ()
104− _ -> Nothing
105−
106−-- | Returns all the new elements that will be added to the 'Map'
107−patchMapWithMoveNewElements :: PatchMapWithMove k p -> [PatchTarget p]
108−patchMapWithMoveNewElements = Map.elems . patchMapWithMoveNewElementsMap
109−
110−patchMapWithMoveNewElementsMap :: PatchMapWithMove k p -> Map k (PatchTarget p)
111−patchMapWithMoveNewElementsMap (PatchMapWithMove p) = Map.mapMaybe f p
112− where f ni = case _nodeInfo_from ni of
113− From_Insert v -> Just v
114− From_Move _ _ -> Nothing
115− From_Delete -> Nothing
181+instance Ord k => Patch (PatchMapWithMove k v) where
182+ type PatchTarget (PatchMapWithMove k v) = Map k v
183+ apply (PatchMapWithMove' p) = apply p
184+
185+-- | Returns all the new elements that will be added to the 'Map'.
186+patchMapWithMoveNewElements :: PatchMapWithMove k v -> [v]
187+patchMapWithMoveNewElements = PM.patchMapWithPatchingMoveNewElements . unPatchMapWithMove'
188+
189+-- | Return a @'Map' k v@ with all the inserts/updates from the given @'PatchMapWithMove' k v@.
190+patchMapWithMoveNewElementsMap :: PatchMapWithMove k v -> Map k v
191+patchMapWithMoveNewElementsMap = PM.patchMapWithPatchingMoveNewElementsMap . unPatchMapWithMove'
116192
117193-- | Create a 'PatchMapWithMove' that, if applied to the given 'Map', will sort
118194-- its values using the given ordering function. The set keys of the 'Map' is
119195-- not changed.
120−patchThatSortsMapWith :: (Ord k, Monoid p) => (PatchTarget p -> PatchTarget p -> Ordering) -> Map k (PatchTarget p) -> PatchMapWithMove k p
121−patchThatSortsMapWith cmp m = PatchMapWithMove $ Map.fromList $ catMaybes $ zipWith g unsorted sorted
122− where unsorted = Map.toList m
123− sorted = sortBy (cmp `on` snd) unsorted
124− f (to, _) (from, _) = if to == from then Nothing else
125− Just (from, to)
126− reverseMapping = Map.fromList $ catMaybes $ zipWith f unsorted sorted
127− g (to, _) (from, _) = if to == from then Nothing else
128− let Just movingTo = Map.lookup from reverseMapping
129− in Just (to, NodeInfo (From_Move from mempty) $ Just movingTo)
196+patchThatSortsMapWith :: Ord k => (v -> v -> Ordering) -> Map k v -> PatchMapWithMove k v
197+patchThatSortsMapWith cmp = PatchMapWithMove' . PM.patchThatSortsMapWith cmp
130198
131199-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
132200-- will produce a 'Map' with the same values as the second 'Map' but with the
133201-- values sorted with the given ordering function.
134−patchThatChangesAndSortsMapWith :: forall k p. (Ord k, Ord (PatchTarget p), Monoid p) => (PatchTarget p -> PatchTarget p -> Ordering) -> Map k (PatchTarget p) -> Map k (PatchTarget p) -> PatchMapWithMove k p
202+patchThatChangesAndSortsMapWith :: (Ord k, Ord v) => (v -> v -> Ordering) -> Map k v -> Map k v -> PatchMapWithMove k v
135203patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatChangesMap oldByIndex newByIndex
136204 where newList = Map.toList newByIndexUnsorted
137205 newByIndex = Map.fromList $ zip (fst <$> newList) $ sortBy cmp $ snd <$> newList
138206
139207-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
140208-- will produce the second 'Map'.
141−patchThatChangesMap :: (Ord k, Ord (PatchTarget p), Monoid p) => Map k (PatchTarget p) -> Map k (PatchTarget p) -> PatchMapWithMove k p
142−patchThatChangesMap oldByIndex newByIndex = patch
143− where oldByValue = Map.fromListWith Set.union $ swap . first Set.singleton <$> Map.toList oldByIndex
144− (insertsAndMoves, unusedValuesByValue) = flip runState oldByValue $ do
145− let f k v = do
146− remainingValues <- get
147− let putRemainingKeys remainingKeys = put $ if Set.null remainingKeys
148− then Map.delete v remainingValues
149− else Map.insert v remainingKeys remainingValues
150− case Map.lookup v remainingValues of
151− Nothing -> return $ NodeInfo (From_Insert v) $ Just undefined -- There's no existing value we can take
152− Just fromKs ->
153− if k `Set.member` fromKs
154− then do
155− putRemainingKeys $ Set.delete k fromKs
156− return $ NodeInfo (From_Move k mempty) $ Just undefined -- There's an existing value, and it's here, so no patch necessary
157− else do
158− (fromK, remainingKeys) <- return . fromJust $ Set.minView fromKs -- There's an existing value, but it's not here; move it here
159− putRemainingKeys remainingKeys
160− return $ NodeInfo (From_Move fromK mempty) $ Just undefined
161− Map.traverseWithKey f newByIndex
162− unusedOldKeys = fold unusedValuesByValue
163− pointlessMove k = \case
164− From_Move k' _ | k == k' -> True
165− _ -> False
166− keyWasMoved k = if k `Map.member` oldByIndex && not (k `Set.member` unusedOldKeys)
167− then Just undefined
168− else Nothing
169− patch = unsafePatchMapWithMove $ 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
209+patchThatChangesMap :: (Ord k, Ord v) => Map k v -> Map k v -> PatchMapWithMove k v
210+patchThatChangesMap oldByIndex newByIndex = PatchMapWithMove' $
211+ PM.patchThatChangesMap oldByIndex newByIndex
212+
213+--
214+-- NodeInfo
215+--
216+
217+-- | Holds the information about each key: where its new value should come from,
218+-- and where its old value should go to
219+newtype NodeInfo k (v :: Type) = NodeInfo' { unNodeInfo' :: PM.NodeInfo k (Proxy v) }
220+
221+deriving instance (Show k, Show p) => Show (NodeInfo k p)
222+deriving instance (Read k, Read p) => Read (NodeInfo k p)
223+deriving instance (Eq k, Eq p) => Eq (NodeInfo k p)
224+deriving instance (Ord k, Ord p) => Ord (NodeInfo k p)
225+
226+{-# COMPLETE NodeInfo #-}
227+pattern NodeInfo :: To k -> From k v -> NodeInfo k v
228+_nodeInfo_to :: NodeInfo k v -> To k
229+_nodeInfo_from :: NodeInfo k v -> From k v
230+pattern NodeInfo { _nodeInfo_to, _nodeInfo_from } = NodeInfo'
231+ PM.NodeInfo
232+ { PM._nodeInfo_to = _nodeInfo_to
233+ , PM._nodeInfo_from = Coerce _nodeInfo_from
234+ }
235+
236+_NodeInfo
237+ :: Iso
238+ (NodeInfo k0 v0)
239+ (NodeInfo k1 v1)
240+ (PM.NodeInfo k0 (Proxy v0))
241+ (PM.NodeInfo k1 (Proxy v1))
242+_NodeInfo = iso unNodeInfo' NodeInfo'
243+
244+instance Functor (NodeInfo k) where
245+ fmap f = runIdentity . traverse (Identity . f)
246+
247+instance Foldable (NodeInfo k) where
248+ foldMap = foldMapDefault
249+
250+instance Traversable (NodeInfo k) where
251+ traverse = bitraverseNodeInfo pure
252+
253+bitraverseNodeInfo
254+ :: Applicative f
255+ => (k0 -> f k1)
256+ -> (v0 -> f v1)
257+ -> NodeInfo k0 v0 -> f (NodeInfo k1 v1)
258+bitraverseNodeInfo fk fv = fmap NodeInfo'
259+ . PM.bitraverseNodeInfo fk (\ ~Proxy -> pure Proxy) fv
260+ . coerce
170261
171262-- | Change the 'From' value of a 'NodeInfo'
172263nodeInfoMapFrom :: (From k v -> From k v) -> NodeInfo k v -> NodeInfo k v
173−nodeInfoMapFrom f ni = ni { _nodeInfo_from = f $ _nodeInfo_from ni }
264+nodeInfoMapFrom f = coerce $ PM.nodeInfoMapFrom (unFrom' . f . From')
174265
175266-- | Change the 'From' value of a 'NodeInfo', using a 'Functor' (or
176267-- 'Applicative', 'Monad', etc.) action to get the new value
177−nodeInfoMapMFrom :: Functor f => (From k v -> f (From k v)) -> NodeInfo k v -> f (NodeInfo k v)
178−nodeInfoMapMFrom f ni = fmap (\result -> ni { _nodeInfo_from = result }) $ f $ _nodeInfo_from ni
268+nodeInfoMapMFrom
269+ :: Functor f
270+ => (From k v -> f (From k v))
271+ -> NodeInfo k v -> f (NodeInfo k v)
272+nodeInfoMapMFrom f = fmap NodeInfo'
273+ . PM.nodeInfoMapMFrom (fmap unFrom' . f . From')
274+ . coerce
179275
180276-- | Set the 'To' field of a 'NodeInfo'
181277nodeInfoSetTo :: To k -> NodeInfo k v -> NodeInfo k v
182−nodeInfoSetTo to ni = ni { _nodeInfo_to = to }
183−
184−-- |Helper data structure used for composing patches using the monoid instance.
185−data Fixup k v
186− = Fixup_Delete
187− | Fixup_Update (These (From k v) (To k))
188−
189−-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
190−instance (Ord k, Monoid p, Eq p, Patch p) => Semigroup (PatchMapWithMove k p) where
191− PatchMapWithMove ma <> PatchMapWithMove mb = PatchMapWithMove m
192− where
193− connections = Map.toList $ Map.intersectionWithKey (\_ a b -> (_nodeInfo_to a, _nodeInfo_from b)) ma mb
194− h :: (k, (Maybe k, From k p)) -> [(k, Fixup k p)]
195− h (_, (mToAfter, editBefore)) = case (mToAfter, editBefore) of
196− (Just toAfter, From_Move fromBefore p)
197− | fromBefore == toAfter && p == mempty
198− -> [(toAfter, Fixup_Delete)]
199− | otherwise
200− -> [ (toAfter, Fixup_Update (This editBefore))
201− , (fromBefore, Fixup_Update (That mToAfter))
202− ]
203− (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
204− (Just toAfter, _) -> [(toAfter, Fixup_Update (This editBefore))]
205− (Nothing, _) -> []
206− mergeFixups _ Fixup_Delete Fixup_Delete = Fixup_Delete
207− mergeFixups _ (Fixup_Update a) (Fixup_Update b)
208− | This x <- a, That y <- b
209− = Fixup_Update $ These x y
210− | That y <- a, This x <- b
211− = Fixup_Update $ These x y
212− mergeFixups _ _ _ = error "PatchMapWithMove: incompatible fixups"
213− fixups = Map.fromListWithKey mergeFixups $ concatMap h connections
214− combineNodeInfos _ nia nib = NodeInfo
215− { _nodeInfo_from = _nodeInfo_from nia
216− , _nodeInfo_to = _nodeInfo_to nib
217− }
218− applyFixup _ ni = \case
219− Fixup_Delete -> Nothing
220− Fixup_Update u -> Just $ NodeInfo
221− { _nodeInfo_from = case _nodeInfo_from ni of
222− f@(From_Move _ p') -> case getHere u of -- The `from` fixup comes from the "old" patch
223− Nothing -> f -- If there's no `from` fixup, just use the "new" `from`
224− Just (From_Insert v) -> From_Insert $ applyAlways p' v
225− Just From_Delete -> From_Delete
226− Just (From_Move oldKey p) -> From_Move oldKey $ p' <> p
227− _ -> error "PatchMapWithMove: fixup for non-move From"
228− , _nodeInfo_to = fromMaybe (_nodeInfo_to ni) $ getThere u
229− }
230− m = Map.differenceWithKey applyFixup (Map.unionWithKey combineNodeInfos ma mb) fixups
231− getHere :: These a b -> Maybe a
232− getHere = \case
233− This a -> Just a
234− These a _ -> Just a
235− That _ -> Nothing
236− getThere :: These a b -> Maybe b
237− getThere = \case
238− This _ -> Nothing
239− These _ b -> Just b
240− That b -> Just b
241−
242−--TODO: Figure out how to implement this in terms of PatchDMapWithMove rather than duplicating it here
243−-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
244−instance (Ord k, Monoid p, Eq p, Patch p) => Monoid (PatchMapWithMove k p) where
245− mempty = PatchMapWithMove mempty
246− mappend = (<>)
278+nodeInfoSetTo = coerce . PM.nodeInfoSetTo
279+
280+--
281+-- From
282+--
283+
284+-- | Describe how a key's new value should be produced
285+newtype From k (v :: Type) = From' { unFrom' :: PM.From k (Proxy v) }
286+
287+{-# COMPLETE From_Insert, From_Delete, From_Move #-}
288+
289+-- | Insert the given value here
290+pattern From_Insert :: v -> From k v
291+pattern From_Insert v = From' (PM.From_Insert v)
292+
293+-- | Delete the existing value, if any, from here
294+pattern From_Delete :: From k v
295+pattern From_Delete = From' PM.From_Delete
296+
297+-- | Move the value here from the given key
298+pattern From_Move :: k -> From k v
299+pattern From_Move k = From' (PM.From_Move k Proxy)
300+
301+bitraverseFrom
302+ :: Applicative f
303+ => (k0 -> f k1)
304+ -> (v0 -> f v1)
305+ -> From k0 v0 -> f (From k1 v1)
306+bitraverseFrom fk fv = fmap From'
307+ . PM.bitraverseFrom fk (\ ~Proxy -> pure Proxy) fv
308+ . coerce
309+
310+makeWrapped ''PatchMapWithMove
311+makeWrapped ''NodeInfo
312+makeWrapped ''From