@@ -2,150 +2,97 @@
2{-# LANGUAGE DeriveTraversable #-}
2{-# LANGUAGE DeriveTraversable #-}
3{-# LANGUAGE FlexibleContexts #-}
3{-# LANGUAGE FlexibleContexts #-}
4{-# LANGUAGE FlexibleInstances #-}
4{-# LANGUAGE FlexibleInstances #-}
5−{-# LANGUAGE GeneralizedNewtypeDeriving #-}
6{-# LANGUAGE LambdaCase #-}
5{-# LANGUAGE LambdaCase #-}
7{-# LANGUAGE MultiParamTypeClasses #-}
6{-# LANGUAGE MultiParamTypeClasses #-}
8{-# LANGUAGE PatternGuards #-}
7{-# LANGUAGE PatternGuards #-}
9−{-# LANGUAGE PatternSynonyms #-}
10{-# LANGUAGE ScopedTypeVariables #-}
8{-# LANGUAGE ScopedTypeVariables #-}
11−{-# LANGUAGE StandaloneDeriving #-}
12{-# LANGUAGE TemplateHaskell #-}
9{-# LANGUAGE TemplateHaskell #-}
13{-# LANGUAGE TypeApplications #-}
10{-# LANGUAGE TypeApplications #-}
14{-# LANGUAGE TypeFamilies #-}
11{-# LANGUAGE TypeFamilies #-}
15−{-# LANGUAGE ViewPatterns #-}
17-- | 'Patch'es on 'Map' that can insert, delete, and move values from one key to
13-- | 'Patch'es on 'Map' that can insert, delete, and move values from one key to
19−module Data.Patch.MapWithMove
15+module Data.Patch.MapWithMove where
26− , patchMapWithMoveInsertAll
31− , unsafePatchMapWithMove
32− , patchMapWithMoveNewElements
33− , patchMapWithMoveNewElementsMap
34− , patchThatSortsMapWith
35− , patchThatChangesAndSortsMapWith
36− , patchThatChangesMap
64−import Data.Kind (Type)
65import Data.Patch.Class
17import Data.Patch.Class
66−import Data.Patch.MapWithPatchingMove (PatchMapWithPatchingMove(..), To)
67−import qualified Data.Patch.MapWithPatchingMove as PM -- already a transparent synonym
69−import Control.Lens
19+import Control.Lens hiding (from, to)
20+import Data.Align (align)
70import Data.List
23import Data.List
71import Data.Map (Map)
24import Data.Map (Map)
72import qualified Data.Map as Map
25import qualified Data.Map as Map
73−import Data.Proxy
26+import Data.Maybe
74#if !MIN_VERSION_base(4,11,0)
27#if !MIN_VERSION_base(4,11,0)
75import Data.Semigroup (Semigroup (..))
28import Data.Semigroup (Semigroup (..))
77−import Data.Traversable (foldMapDefault)
30+import Data.Set (Set)
31+import qualified Data.Set as Set
32+import Data.These (These(..))
79-- | Patch a Map with additions, deletions, and moves. Invariant: If key @k1@
34-- | Patch a Map with additions, deletions, and moves. Invariant: If key @k1@
80-- is coming from @From_Move k2@, then key @k2@ should be going to @Just k1@,
35-- is coming from @From_Move k2@, then key @k2@ should be going to @Just k1@,
81-- and vice versa. There should never be any unpaired From/To keys.
36-- and vice versa. There should never be any unpaired From/To keys.
82−newtype PatchMapWithMove k (v :: Type) = PatchMapWithMove'
37+newtype PatchMapWithMove k v = PatchMapWithMove
83− { -- | Extract the underlying 'PatchMapWithPatchingMove k (Proxy v)'
38+ { -- | Extract the internal representation of the 'PatchMapWithMove'
84− unPatchMapWithMove' :: PatchMapWithPatchingMove k (Proxy v)
39+ unPatchMapWithMove :: Map k (NodeInfo k v)
86 deriving ( Show, Read, Eq, Ord
41 deriving ( Show, Read, Eq, Ord
87−-- Haddock cannot handle documentation here before GHC 8.6
42+ , Functor, Foldable, Traversable
89−#if __GLASGOW_HASKELL__ >= 806
90− -- | Compose patches having the same effect as applying the
91− -- patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p .
98−pattern Coerce :: Coercible a b => a -> b
45+-- | Holds the information about each key: where its new value should come from,
99−pattern Coerce x <- (coerce -> x)
46+-- and where its old value should go to
100− where Coerce x = coerce x
47+data NodeInfo k v = NodeInfo
101−
48+ { _nodeInfo_from :: !(From k v)
102−{-# COMPLETE PatchMapWithMove #-}
49+ -- ^ Where do we get the new value for this key?
103−pattern PatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
50+ , _nodeInfo_to :: !(To k)
104−-- | Extract the representation of the 'PatchMapWithMove' as a map of
51+ -- ^ If the old value is being kept (i.e. moved rather than deleted or
105−-- 'NodeInfo'.
52+ -- replaced), where is it going?
106−unPatchMapWithMove :: PatchMapWithMove k v -> Map k (NodeInfo k v)
53+ }
107−pattern PatchMapWithMove { unPatchMapWithMove } = PatchMapWithMove' (PatchMapWithPatchingMove (Coerce unPatchMapWithMove))
54+ deriving (Show, Read, Eq, Ord, Functor, Foldable, Traversable)
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
117−instance Functor (PatchMapWithMove k) where
56+-- | Describe how a key's new value should be produced
118− fmap f = runIdentity . traverse (Identity . f)
57+data From k v
58+ = From_Insert v -- ^ Insert the given value here
59+ | From_Delete -- ^ Delete the existing value, if any, from here
60+ | From_Move !k -- ^ Move the value here from the given key
61+ deriving (Show, Read, Eq, Ord, Functor, Foldable, Traversable)
120−instance Foldable (PatchMapWithMove k) where
63+-- | Describe where a key's old value will go. If this is 'Just', that means
121− foldMap = foldMapDefault
64+-- the key's old value will be moved to the given other key; if it is 'Nothing',
65+-- that means it will be deleted.
123−instance Traversable (PatchMapWithMove k) where
68+makeWrapped ''PatchMapWithMove
129instance FunctorWithIndex k (PatchMapWithMove k)
70instance FunctorWithIndex k (PatchMapWithMove k)
130instance FoldableWithIndex k (PatchMapWithMove k)
71instance FoldableWithIndex k (PatchMapWithMove k)
131instance TraversableWithIndex k (PatchMapWithMove k) where
72instance TraversableWithIndex k (PatchMapWithMove k) where
132 itraverse = itraversed . Indexed
73 itraverse = itraversed . Indexed
133− itraversed =
74+ itraversed = _Wrapped .> itraversed <. traversed
134− _PatchMapWithMove .>
138-- | Create a 'PatchMapWithMove', validating it
76-- | Create a 'PatchMapWithMove', validating it
139patchMapWithMove :: Ord k => Map k (NodeInfo k v) -> Maybe (PatchMapWithMove k v)
77patchMapWithMove :: Ord k => Map k (NodeInfo k v) -> Maybe (PatchMapWithMove k v)
140−patchMapWithMove = fmap PatchMapWithMove' . PM.patchMapWithPatchingMove . coerce
78+patchMapWithMove m = if valid then Just $ PatchMapWithMove m else Nothing
79+ where valid = forwardLinks == backwardLinks
80+ forwardLinks = Map.mapMaybe _nodeInfo_to m
81+ backwardLinks = Map.fromList $ catMaybes $ flip fmap (Map.toList m) $ \(to, v) ->
82+ case _nodeInfo_from v of
83+ From_Move from -> Just (from, to)
142-- | Create a 'PatchMapWithMove' that inserts everything in the given 'Map'
86-- | Create a 'PatchMapWithMove' that inserts everything in the given 'Map'
143patchMapWithMoveInsertAll :: Map k v -> PatchMapWithMove k v
87patchMapWithMoveInsertAll :: Map k v -> PatchMapWithMove k v
144−patchMapWithMoveInsertAll = PatchMapWithMove' . PM.patchMapWithPatchingMoveInsertAll
88+patchMapWithMoveInsertAll m = PatchMapWithMove $ flip fmap m $ \v -> NodeInfo
89+ { _nodeInfo_from = From_Insert v
90+ , _nodeInfo_to = Nothing
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'.
93-- | Make a @'PatchMapWithMove' k v@ which has the effect of inserting or updating a value @v@ to the given key @k@, like 'Map.insert'.
147insertMapKey :: k -> v -> PatchMapWithMove k v
94insertMapKey :: k -> v -> PatchMapWithMove k v
148−insertMapKey k v = PatchMapWithMove' $ PM.insertMapKey k v
95+insertMapKey k v = PatchMapWithMove . Map.singleton k $ NodeInfo (From_Insert v) Nothing
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:
97-- |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:
@@ -153,160 +100,188 @@ insertMapKey k v = PatchMapWithMove' $ PM.insertMapKey k v
153-- 'Map.delete' src (maybe map ('Map.insert' dst) (Map.lookup src map))
100-- 'Map.delete' src (maybe map ('Map.insert' dst) (Map.lookup src map))
155moveMapKey :: Ord k => k -> k -> PatchMapWithMove k v
102moveMapKey :: Ord k => k -> k -> PatchMapWithMove k v
156−moveMapKey src dst = PatchMapWithMove' $ PM.moveMapKey src dst
103+moveMapKey src dst
104+ | src == dst = mempty
106+ PatchMapWithMove $ Map.fromList
107+ [ (dst, NodeInfo (From_Move src) Nothing)
108+ , (src, NodeInfo From_Delete (Just dst))
158-- |Make a @'PatchMapWithMove' k v@ which has the effect of swapping two keys in the mapping, equivalent to:
111-- |Make a @'PatchMapWithMove' k v@ which has the effect of swapping two keys in the mapping, equivalent to:
161-- let aMay = Map.lookup a map
114-- let aMay = Map.lookup a map
162-- bMay = Map.lookup b map
115-- bMay = Map.lookup b map
163−-- in maybe id (Map.insert a) (bMay <> aMay)
116+-- in maybe id (Map.insert a) (bMay `mplus` aMay)
164−-- . maybe id (Map.insert b) (aMay <> bMay)
117+-- . maybe id (Map.insert b) (aMay `mplus` bMay)
165-- . Map.delete a . Map.delete b $ map
118-- . Map.delete a . Map.delete b $ map
167swapMapKey :: Ord k => k -> k -> PatchMapWithMove k v
120swapMapKey :: Ord k => k -> k -> PatchMapWithMove k v
168−swapMapKey src dst = PatchMapWithMove' $ PM.swapMapKey src dst
121+swapMapKey src dst
122+ | src == dst = mempty
124+ PatchMapWithMove $ Map.fromList
125+ [ (dst, NodeInfo (From_Move src) (Just src))
126+ , (src, NodeInfo (From_Move dst) (Just dst))
170-- |Make a @'PatchMapWithMove' k v@ which has the effect of deleting a key in the mapping, equivalent to 'Map.delete'.
129-- |Make a @'PatchMapWithMove' k v@ which has the effect of deleting a key in the mapping, equivalent to 'Map.delete'.
171deleteMapKey :: k -> PatchMapWithMove k v
130deleteMapKey :: k -> PatchMapWithMove k v
172−deleteMapKey = PatchMapWithMove' . PM.deleteMapKey
131+deleteMapKey k = PatchMapWithMove . Map.singleton k $ NodeInfo From_Delete Nothing
174-- | Wrap a @'Map' k (NodeInfo k v)@ representing patch changes into a @'PatchMapWithMove' k v@, without checking any invariants.
133-- | Wrap a @'Map' k (NodeInfo k v)@ representing patch changes into a @'PatchMapWithMove' k v@, without checking any invariants.
176-- __Warning:__ when using this function, you must ensure that the invariants of 'PatchMapWithMove' are preserved; they will not be checked.
135-- __Warning:__ when using this function, you must ensure that the invariants of 'PatchMapWithMove' are preserved; they will not be checked.
177unsafePatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
136unsafePatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
178−unsafePatchMapWithMove = coerce PM.unsafePatchMapWithPatchingMove
137+unsafePatchMapWithMove = PatchMapWithMove
180-- | Apply the insertions, deletions, and moves to a given 'Map'
139-- | Apply the insertions, deletions, and moves to a given 'Map'
181instance Ord k => Patch (PatchMapWithMove k v) where
140instance Ord k => Patch (PatchMapWithMove k v) where
182 type PatchTarget (PatchMapWithMove k v) = Map k v
141 type PatchTarget (PatchMapWithMove k v) = Map k v
183− apply (PatchMapWithMove' p) = apply p
142+ apply (PatchMapWithMove p) 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?
143+ where insertions = flip Map.mapMaybeWithKey p $ \_ ni -> case _nodeInfo_from ni of
144+ From_Insert v -> Just v
145+ From_Move k -> Map.lookup k old
146+ From_Delete -> Nothing
147+ deletions = flip Map.mapMaybeWithKey p $ \_ ni -> case _nodeInfo_from ni of
148+ From_Delete -> Just ()
185-- | Returns all the new elements that will be added to the 'Map'.
151-- | Returns all the new elements that will be added to the 'Map'.
186patchMapWithMoveNewElements :: PatchMapWithMove k v -> [v]
152patchMapWithMoveNewElements :: PatchMapWithMove k v -> [v]
187−patchMapWithMoveNewElements = PM.patchMapWithPatchingMoveNewElements . unPatchMapWithMove'
153+patchMapWithMoveNewElements = Map.elems . patchMapWithMoveNewElementsMap
189-- | Return a @'Map' k v@ with all the inserts/updates from the given @'PatchMapWithMove' k v@.
155-- | Return a @'Map' k v@ with all the inserts/updates from the given @'PatchMapWithMove' k v@.
190patchMapWithMoveNewElementsMap :: PatchMapWithMove k v -> Map k v
156patchMapWithMoveNewElementsMap :: PatchMapWithMove k v -> Map k v
191−patchMapWithMoveNewElementsMap = PM.patchMapWithPatchingMoveNewElementsMap . unPatchMapWithMove'
157+patchMapWithMoveNewElementsMap (PatchMapWithMove p) = Map.mapMaybe f p
158+ where f ni = case _nodeInfo_from ni of
159+ From_Insert v -> Just v
160+ From_Move _ -> Nothing
161+ From_Delete -> Nothing
193-- | Create a 'PatchMapWithMove' that, if applied to the given 'Map', will sort
163-- | Create a 'PatchMapWithMove' that, if applied to the given 'Map', will sort
194-- its values using the given ordering function. The set keys of the 'Map' is
164-- its values using the given ordering function. The set keys of the 'Map' is
195-- not changed.
165-- not changed.
196patchThatSortsMapWith :: Ord k => (v -> v -> Ordering) -> Map k v -> PatchMapWithMove k v
166patchThatSortsMapWith :: Ord k => (v -> v -> Ordering) -> Map k v -> PatchMapWithMove k v
197−patchThatSortsMapWith cmp = PatchMapWithMove' . PM.patchThatSortsMapWith cmp
167+patchThatSortsMapWith cmp m = PatchMapWithMove $ Map.fromList $ catMaybes $ zipWith g unsorted sorted
168+ where unsorted = Map.toList m
169+ sorted = sortBy (cmp `on` snd) unsorted
170+ f (to, _) (from, _) = if to == from then Nothing else
172+ reverseMapping = Map.fromList $ catMaybes $ zipWith f unsorted sorted
173+ g (to, _) (from, _) = if to == from then Nothing else
174+ let Just movingTo = Map.lookup to reverseMapping
175+ in Just (to, NodeInfo (From_Move from) $ Just movingTo)
199-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
177-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
200-- will produce a 'Map' with the same values as the second 'Map' but with the
178-- will produce a 'Map' with the same values as the second 'Map' but with the
201-- values sorted with the given ordering function.
179-- values sorted with the given ordering function.
202−patchThatChangesAndSortsMapWith :: (Ord k, Ord v) => (v -> v -> Ordering) -> Map k v -> Map k v -> PatchMapWithMove k v
180+patchThatChangesAndSortsMapWith :: forall k v. (Ord k, Ord v) => (v -> v -> Ordering) -> Map k v -> Map k v -> PatchMapWithMove k v
203patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatChangesMap oldByIndex newByIndex
181patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatChangesMap oldByIndex newByIndex
204 where newList = Map.toList newByIndexUnsorted
182 where newList = Map.toList newByIndexUnsorted
205 newByIndex = Map.fromList $ zip (fst <$> newList) $ sortBy cmp $ snd <$> newList
183 newByIndex = Map.fromList $ zip (fst <$> newList) $ sortBy cmp $ snd <$> newList
207-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
185-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
208-- will produce the second 'Map'.
186-- will produce the second 'Map'.
209−patchThatChangesMap :: (Ord k, Ord v) => Map k v -> Map k v -> PatchMapWithMove k v
187+patchThatChangesMap :: forall k v. (Ord k, Ord v) => Map k v -> Map k v -> PatchMapWithMove k v
210−patchThatChangesMap oldByIndex newByIndex = PatchMapWithMove' $
188+patchThatChangesMap oldByIndex newByIndex = patch
211− PM.patchThatChangesMap oldByIndex newByIndex
189+ where invert :: Map k v -> Map v (Set k)
212−
190+ invert = Map.fromListWith (<>) . fmap (\(k, v) -> (v, Set.singleton k)) . Map.toList
213−--
191+ -- In the places where we use unionDistinct, a non-distinct key indicates a bug in this function
214−-- NodeInfo
192+ unionDistinct :: forall k' v'. Ord k' => Map k' v' -> Map k' v' -> Map k' v'
215−--
193+ unionDistinct = Map.unionWith (error "patchThatChangesMap: non-distinct keys")
216−
194+ unionPairDistinct :: (Map k (From k v), Map k (To k)) -> (Map k (From k v), Map k (To k)) -> (Map k (From k v), Map k (To k))
217−-- | Holds the information about each key: where its new value should come from,
195+ unionPairDistinct (oldFroms, oldTos) (newFroms, newTos) = (unionDistinct oldFroms newFroms, unionDistinct oldTos newTos)
218−-- and where its old value should go to
196+ -- Generate patch info for a single value
219−newtype NodeInfo k (v :: Type) = NodeInfo' { unNodeInfo' :: PM.NodeInfo k (Proxy v) }
197+ -- Keys that are found in both the old and new sets will not be patched
220−
198+ -- Keys that are found in only the old set will be moved to a new position if any are available; otherwise they will be deleted
221−deriving instance (Show k, Show p) => Show (NodeInfo k p)
199+ -- Keys that are found in only the new set will be populated by moving an old key if any are available; otherwise they will be inserted
222−deriving instance (Read k, Read p) => Read (NodeInfo k p)
200+ patchSingleValue :: v -> Set k -> Set k -> (Map k (From k v), Map k (To k))
223−deriving instance (Eq k, Eq p) => Eq (NodeInfo k p)
201+ patchSingleValue v oldKeys newKeys = foldl' unionPairDistinct mempty $ align (toList $ oldKeys `Set.difference` newKeys) (toList $ newKeys `Set.difference` oldKeys) <&> \case
224−deriving instance (Ord k, Ord p) => Ord (NodeInfo k p)
202+ This oldK -> (mempty, Map.singleton oldK Nothing) -- There's nowhere for this value to go, so we know we are deleting it
225−
203+ That newK -> (Map.singleton newK $ From_Insert v, mempty) -- There's nowhere fo this value to come from, so we know we are inserting it
226−{-# COMPLETE NodeInfo #-}
204+ These oldK newK -> (Map.singleton newK $ From_Move oldK, Map.singleton oldK $ Just newK)
227−pattern NodeInfo :: To k -> From k v -> NodeInfo k v
205+ -- Run patchSingleValue on a These. Missing old or new sets are considered empty
228−_nodeInfo_to :: NodeInfo k v -> To k
206+ patchSingleValueThese :: v -> These (Set k) (Set k) -> (Map k (From k v), Map k (To k))
229−_nodeInfo_from :: NodeInfo k v -> From k v
207+ patchSingleValueThese v = \case
230−pattern NodeInfo { _nodeInfo_to, _nodeInfo_from } = NodeInfo'
208+ This oldKeys -> patchSingleValue v oldKeys mempty
231− PM.NodeInfo
209+ That newKeys -> patchSingleValue v mempty newKeys
232− { PM._nodeInfo_to = _nodeInfo_to
210+ These oldKeys newKeys -> patchSingleValue v oldKeys newKeys
233− , PM._nodeInfo_from = Coerce _nodeInfo_from
211+ -- Generate froms and tos for all values, then merge them together
234− }
212+ (froms, tos) = foldl' unionPairDistinct mempty $ Map.mapWithKey patchSingleValueThese $ align (invert oldByIndex) (invert newByIndex)
235−
213+ patch = unsafePatchMapWithMove $ align froms tos <&> \case
236−_NodeInfo
214+ This from -> NodeInfo from Nothing -- Since we don't have a 'to' record for this key, that must mean it isn't being moved anywhere, so it should be deleted.
237− :: Iso
215+ That to -> NodeInfo From_Delete to -- Since we don't have a 'from' record for this key, it must be getting deleted
238− (NodeInfo k0 v0)
216+ These from to -> NodeInfo from to
240− (PM.NodeInfo k0 (Proxy v0))
241− (PM.NodeInfo k1 (Proxy v1))
242−_NodeInfo = iso unNodeInfo' NodeInfo'
244−instance Functor (NodeInfo k) where
245− fmap f = runIdentity . traverse (Identity . f)
247−instance Foldable (NodeInfo k) where
248− foldMap = foldMapDefault
250−instance Traversable (NodeInfo k) where
251− traverse = bitraverseNodeInfo pure
257− -> NodeInfo k0 v0 -> f (NodeInfo k1 v1)
258−bitraverseNodeInfo fk fv = fmap NodeInfo'
259− . PM.bitraverseNodeInfo fk (\ ~Proxy -> pure Proxy) fv
262-- | Change the 'From' value of a 'NodeInfo'
218-- | Change the 'From' value of a 'NodeInfo'
263nodeInfoMapFrom :: (From k v -> From k v) -> NodeInfo k v -> NodeInfo k v
219nodeInfoMapFrom :: (From k v -> From k v) -> NodeInfo k v -> NodeInfo k v
264−nodeInfoMapFrom f = coerce $ PM.nodeInfoMapFrom (unFrom' . f . From')
220+nodeInfoMapFrom f ni = ni { _nodeInfo_from = f $ _nodeInfo_from ni }
266-- | Change the 'From' value of a 'NodeInfo', using a 'Functor' (or
222-- | Change the 'From' value of a 'NodeInfo', using a 'Functor' (or
267-- 'Applicative', 'Monad', etc.) action to get the new value
223-- 'Applicative', 'Monad', etc.) action to get the new value
270− => (From k v -> f (From k v))
271− -> NodeInfo k v -> f (NodeInfo k v)
224+nodeInfoMapMFrom :: Functor f => (From k v -> f (From k v)) -> NodeInfo k v -> f (NodeInfo k v)
272−nodeInfoMapMFrom f = fmap NodeInfo'
225+nodeInfoMapMFrom f ni = fmap (\result -> ni { _nodeInfo_from = result }) $ f $ _nodeInfo_from ni
273− . PM.nodeInfoMapMFrom (fmap unFrom' . f . From')
276-- | Set the 'To' field of a 'NodeInfo'
227-- | Set the 'To' field of a 'NodeInfo'
277nodeInfoSetTo :: To k -> NodeInfo k v -> NodeInfo k v
228nodeInfoSetTo :: To k -> NodeInfo k v -> NodeInfo k v
278−nodeInfoSetTo = coerce . PM.nodeInfoSetTo
229+nodeInfoSetTo to ni = ni { _nodeInfo_to = to }
280−--
231+-- |Helper data structure used for composing patches using the monoid instance.
281−-- From
232+data Fixup k v
282−--
233+ = Fixup_Delete
283−
234+ | Fixup_Update (These (From k v) (To k))
284−-- | Describe how a key's new value should be produced
235+
285−newtype From k (v :: Type) = From' { unFrom' :: PM.From k (Proxy v) }
236+-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
286−
237+instance Ord k => Semigroup (PatchMapWithMove k v) where
287−{-# COMPLETE From_Insert, From_Delete, From_Move #-}
238+ PatchMapWithMove ma <> PatchMapWithMove mb = PatchMapWithMove m
289−-- | Insert the given value here
240+ connections = Map.toList $ Map.intersectionWithKey (\_ a b -> (_nodeInfo_to a, _nodeInfo_from b)) ma mb
290−pattern From_Insert :: v -> From k v
241+ h :: (k, (Maybe k, From k v)) -> [(k, Fixup k v)]
291−pattern From_Insert v = From' (PM.From_Insert v)
242+ h (_, (mToAfter, editBefore)) = case (mToAfter, editBefore) of
292−
243+ (Just toAfter, From_Move fromBefore)
293−-- | Delete the existing value, if any, from here
244+ | fromBefore == toAfter
294−pattern From_Delete :: From k v
245+ -> [(toAfter, Fixup_Delete)]
295−pattern From_Delete = From' PM.From_Delete
246+ | otherwise
296−
247+ -> [ (toAfter, Fixup_Update (This editBefore))
297−-- | Move the value here from the given key
248+ , (fromBefore, Fixup_Update (That mToAfter))
298−pattern From_Move :: k -> From k v
249+ ]
299−pattern From_Move k = From' (PM.From_Move k Proxy)
250+ (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
300−
251+ (Just toAfter, _) -> [(toAfter, Fixup_Update (This editBefore))]
301−bitraverseFrom
252+ (Nothing, _) -> []
302− :: Applicative f
253+ mergeFixups _ Fixup_Delete Fixup_Delete = Fixup_Delete
303− => (k0 -> f k1)
254+ mergeFixups _ (Fixup_Update a) (Fixup_Update b)
304− -> (v0 -> f v1)
255+ | This x <- a, That y <- b
305− -> From k0 v0 -> f (From k1 v1)
256+ = Fixup_Update $ These x y
306−bitraverseFrom fk fv = fmap From'
257+ | That y <- a, This x <- b
307− . PM.bitraverseFrom fk (\ ~Proxy -> pure Proxy) fv
258+ = Fixup_Update $ These x y
308− . coerce
259+ mergeFixups _ _ _ = error "PatchMapWithMove: incompatible fixups"
309−
260+ fixups = Map.fromListWithKey mergeFixups $ concatMap h connections
310−makeWrapped ''PatchMapWithMove
261+ combineNodeInfos _ nia nib = NodeInfo
311−makeWrapped ''NodeInfo
262+ { _nodeInfo_from = _nodeInfo_from nia
312−makeWrapped ''From
263+ , _nodeInfo_to = _nodeInfo_to nib
265+ applyFixup _ ni = \case
266+ Fixup_Delete -> Nothing
267+ Fixup_Update u -> Just $ NodeInfo
268+ { _nodeInfo_from = fromMaybe (_nodeInfo_from ni) $ getHere u
269+ , _nodeInfo_to = fromMaybe (_nodeInfo_to ni) $ getThere u
271+ m = Map.differenceWithKey applyFixup (Map.unionWithKey combineNodeInfos ma mb) fixups
272+ getHere :: These a b -> Maybe a
277+ getThere :: These a b -> Maybe b
283+--TODO: Figure out how to implement this in terms of PatchDMapWithMove rather than duplicating it here
284+-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
285+instance Ord k => Monoid (PatchMapWithMove k v) where
286+ mempty = PatchMapWithMove mempty