@@ -2,150 +2,98 @@
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.Arrow
20+import Control.Lens hiding (from, to)
21+import Control.Monad.Trans.State
70import Data.List
24import Data.List
71import Data.Map (Map)
25import Data.Map (Map)
72import qualified Data.Map as Map
26import qualified Data.Map as Map
73−import Data.Proxy
27+import Data.Maybe
74#if !MIN_VERSION_base(4,11,0)
28#if !MIN_VERSION_base(4,11,0)
75import Data.Semigroup (Semigroup (..))
29import Data.Semigroup (Semigroup (..))
77−import Data.Traversable (foldMapDefault)
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@
35-- | 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@,
36-- 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.
37-- and vice versa. There should never be any unpaired From/To keys.
82−newtype PatchMapWithMove k (v :: Type) = PatchMapWithMove'
38+newtype PatchMapWithMove k v = PatchMapWithMove
83− { -- | Extract the underlying 'PatchMapWithPatchingMove k (Proxy v)'
39+ { -- | Extract the internal representation of the 'PatchMapWithMove'
84− unPatchMapWithMove' :: PatchMapWithPatchingMove k (Proxy v)
40+ unPatchMapWithMove :: Map k (NodeInfo k v)
86 deriving ( Show, Read, Eq, Ord
42 deriving ( Show, Read, Eq, Ord
87−-- Haddock cannot handle documentation here before GHC 8.6
43+ , 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
46+-- | Holds the information about each key: where its new value should come from,
99−pattern Coerce x <- (coerce -> x)
47+-- and where its old value should go to
100− where Coerce x = coerce x
48+data NodeInfo k v = NodeInfo
101−
49+ { _nodeInfo_from :: !(From k v)
102−{-# COMPLETE PatchMapWithMove #-}
50+ -- ^ Where do we get the new value for this key?
103−pattern PatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
51+ , _nodeInfo_to :: !(To k)
104−-- | Extract the representation of the 'PatchMapWithMove' as a map of
52+ -- ^ If the old value is being kept (i.e. moved rather than deleted or
105−-- 'NodeInfo'.
53+ -- replaced), where is it going?
106−unPatchMapWithMove :: PatchMapWithMove k v -> Map k (NodeInfo k v)
54+ }
107−pattern PatchMapWithMove { unPatchMapWithMove } = PatchMapWithMove' (PatchMapWithPatchingMove (Coerce unPatchMapWithMove))
55+ 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
57+-- | Describe how a key's new value should be produced
118− fmap f = runIdentity . traverse (Identity . f)
58+data From k v
59+ = From_Insert v -- ^ Insert the given value here
60+ | From_Delete -- ^ Delete the existing value, if any, from here
61+ | From_Move !k -- ^ Move the value here from the given key
62+ deriving (Show, Read, Eq, Ord, Functor, Foldable, Traversable)
120−instance Foldable (PatchMapWithMove k) where
64+-- | Describe where a key's old value will go. If this is 'Just', that means
121− foldMap = foldMapDefault
65+-- the key's old value will be moved to the given other key; if it is 'Nothing',
66+-- that means it will be deleted.
123−instance Traversable (PatchMapWithMove k) where
69+makeWrapped ''PatchMapWithMove
129instance FunctorWithIndex k (PatchMapWithMove k)
71instance FunctorWithIndex k (PatchMapWithMove k)
130instance FoldableWithIndex k (PatchMapWithMove k)
72instance FoldableWithIndex k (PatchMapWithMove k)
131instance TraversableWithIndex k (PatchMapWithMove k) where
73instance TraversableWithIndex k (PatchMapWithMove k) where
132 itraverse = itraversed . Indexed
74 itraverse = itraversed . Indexed
133− itraversed =
75+ itraversed = _Wrapped .> itraversed <. traversed
134− _PatchMapWithMove .>
138-- | Create a 'PatchMapWithMove', validating it
77-- | Create a 'PatchMapWithMove', validating it
139patchMapWithMove :: Ord k => Map k (NodeInfo k v) -> Maybe (PatchMapWithMove k v)
78patchMapWithMove :: Ord k => Map k (NodeInfo k v) -> Maybe (PatchMapWithMove k v)
140−patchMapWithMove = fmap PatchMapWithMove' . PM.patchMapWithPatchingMove . coerce
79+patchMapWithMove m = if valid then Just $ PatchMapWithMove m else Nothing
80+ where valid = forwardLinks == backwardLinks
81+ forwardLinks = Map.mapMaybe _nodeInfo_to m
82+ backwardLinks = Map.fromList $ catMaybes $ flip fmap (Map.toList m) $ \(to, v) ->
83+ case _nodeInfo_from v of
84+ From_Move from -> Just (from, to)
142-- | Create a 'PatchMapWithMove' that inserts everything in the given 'Map'
87-- | Create a 'PatchMapWithMove' that inserts everything in the given 'Map'
143patchMapWithMoveInsertAll :: Map k v -> PatchMapWithMove k v
88patchMapWithMoveInsertAll :: Map k v -> PatchMapWithMove k v
144−patchMapWithMoveInsertAll = PatchMapWithMove' . PM.patchMapWithPatchingMoveInsertAll
89+patchMapWithMoveInsertAll m = PatchMapWithMove $ flip fmap m $ \v -> NodeInfo
90+ { _nodeInfo_from = From_Insert v
91+ , _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'.
94-- | 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
95insertMapKey :: k -> v -> PatchMapWithMove k v
148−insertMapKey k v = PatchMapWithMove' $ PM.insertMapKey k v
96+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:
98-- |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:
@@ -153,53 +101,84 @@ insertMapKey k v = PatchMapWithMove' $ PM.insertMapKey k v
153-- 'Map.delete' src (maybe map ('Map.insert' dst) (Map.lookup src map))
101-- 'Map.delete' src (maybe map ('Map.insert' dst) (Map.lookup src map))
155moveMapKey :: Ord k => k -> k -> PatchMapWithMove k v
103moveMapKey :: Ord k => k -> k -> PatchMapWithMove k v
156−moveMapKey src dst = PatchMapWithMove' $ PM.moveMapKey src dst
104+moveMapKey src dst
105+ | src == dst = mempty
107+ PatchMapWithMove $ Map.fromList
108+ [ (dst, NodeInfo (From_Move src) Nothing)
109+ , (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:
112-- |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
115-- let aMay = Map.lookup a map
162-- bMay = Map.lookup b map
116-- bMay = Map.lookup b map
163−-- in maybe id (Map.insert a) (bMay <> aMay)
117+-- in maybe id (Map.insert a) (bMay `mplus` aMay)
164−-- . maybe id (Map.insert b) (aMay <> bMay)
118+-- . maybe id (Map.insert b) (aMay `mplus` bMay)
165-- . Map.delete a . Map.delete b $ map
119-- . Map.delete a . Map.delete b $ map
167swapMapKey :: Ord k => k -> k -> PatchMapWithMove k v
121swapMapKey :: Ord k => k -> k -> PatchMapWithMove k v
168−swapMapKey src dst = PatchMapWithMove' $ PM.swapMapKey src dst
122+swapMapKey src dst
123+ | src == dst = mempty
125+ PatchMapWithMove $ Map.fromList
126+ [ (dst, NodeInfo (From_Move src) (Just src))
127+ , (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'.
130-- |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
131deleteMapKey :: k -> PatchMapWithMove k v
172−deleteMapKey = PatchMapWithMove' . PM.deleteMapKey
132+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.
134-- | 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.
136-- __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
137unsafePatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
178−unsafePatchMapWithMove = coerce PM.unsafePatchMapWithPatchingMove
138+unsafePatchMapWithMove = PatchMapWithMove
180-- | Apply the insertions, deletions, and moves to a given 'Map'
140-- | Apply the insertions, deletions, and moves to a given 'Map'
181instance Ord k => Patch (PatchMapWithMove k v) where
141instance Ord k => Patch (PatchMapWithMove k v) where
182 type PatchTarget (PatchMapWithMove k v) = Map k v
142 type PatchTarget (PatchMapWithMove k v) = Map k v
183− apply (PatchMapWithMove' p) = apply p
143+ 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?
144+ where insertions = flip Map.mapMaybeWithKey p $ \_ ni -> case _nodeInfo_from ni of
145+ From_Insert v -> Just v
146+ From_Move k -> Map.lookup k old
147+ From_Delete -> Nothing
148+ deletions = flip Map.mapMaybeWithKey p $ \_ ni -> case _nodeInfo_from ni of
149+ From_Delete -> Just ()
185-- | Returns all the new elements that will be added to the 'Map'.
152-- | Returns all the new elements that will be added to the 'Map'.
186patchMapWithMoveNewElements :: PatchMapWithMove k v -> [v]
153patchMapWithMoveNewElements :: PatchMapWithMove k v -> [v]
187−patchMapWithMoveNewElements = PM.patchMapWithPatchingMoveNewElements . unPatchMapWithMove'
154+patchMapWithMoveNewElements = Map.elems . patchMapWithMoveNewElementsMap
189-- | Return a @'Map' k v@ with all the inserts/updates from the given @'PatchMapWithMove' k v@.
156-- | Return a @'Map' k v@ with all the inserts/updates from the given @'PatchMapWithMove' k v@.
190patchMapWithMoveNewElementsMap :: PatchMapWithMove k v -> Map k v
157patchMapWithMoveNewElementsMap :: PatchMapWithMove k v -> Map k v
191−patchMapWithMoveNewElementsMap = PM.patchMapWithPatchingMoveNewElementsMap . unPatchMapWithMove'
158+patchMapWithMoveNewElementsMap (PatchMapWithMove p) = Map.mapMaybe f p
159+ where f ni = case _nodeInfo_from ni of
160+ From_Insert v -> Just v
161+ From_Move _ -> Nothing
162+ From_Delete -> Nothing
193-- | Create a 'PatchMapWithMove' that, if applied to the given 'Map', will sort
164-- | 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
165-- its values using the given ordering function. The set keys of the 'Map' is
195-- not changed.
166-- not changed.
196patchThatSortsMapWith :: Ord k => (v -> v -> Ordering) -> Map k v -> PatchMapWithMove k v
167patchThatSortsMapWith :: Ord k => (v -> v -> Ordering) -> Map k v -> PatchMapWithMove k v
197−patchThatSortsMapWith cmp = PatchMapWithMove' . PM.patchThatSortsMapWith cmp
168+patchThatSortsMapWith cmp m = PatchMapWithMove $ Map.fromList $ catMaybes $ zipWith g unsorted sorted
169+ where unsorted = Map.toList m
170+ sorted = sortBy (cmp `on` snd) unsorted
171+ f (to, _) (from, _) = if to == from then Nothing else
173+ reverseMapping = Map.fromList $ catMaybes $ zipWith f unsorted sorted
174+ g (to, _) (from, _) = if to == from then Nothing else
175+ let Just movingTo = Map.lookup to reverseMapping
176+ in Just (to, NodeInfo (From_Move from) $ Just movingTo)
199-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
178-- | 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
179-- will produce a 'Map' with the same values as the second 'Map' but with the
201-- values sorted with the given ordering function.
180-- 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
181+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
182patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatChangesMap oldByIndex newByIndex
204 where newList = Map.toList newByIndexUnsorted
183 where newList = Map.toList newByIndexUnsorted
205 newByIndex = Map.fromList $ zip (fst <$> newList) $ sortBy cmp $ snd <$> newList
184 newByIndex = Map.fromList $ zip (fst <$> newList) $ sortBy cmp $ snd <$> newList
@@ -207,106 +186,104 @@ patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatCha
207-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
186-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
208-- will produce the second 'Map'.
187-- will produce the second 'Map'.
209patchThatChangesMap :: (Ord k, Ord v) => Map k v -> Map k v -> PatchMapWithMove k v
188patchThatChangesMap :: (Ord k, Ord v) => Map k v -> Map k v -> PatchMapWithMove k v
210−patchThatChangesMap oldByIndex newByIndex = PatchMapWithMove' $
189+patchThatChangesMap oldByIndex newByIndex = patch
211− PM.patchThatChangesMap oldByIndex newByIndex
190+ where oldByValue = Map.fromListWith Set.union $ swap . first Set.singleton <$> Map.toList oldByIndex
212−
191+ (insertsAndMoves, unusedValuesByValue) = flip runState oldByValue $ do
213−--
192+ let f k v = do
214−-- NodeInfo
193+ remainingValues <- get
215−--
194+ let putRemainingKeys remainingKeys = put $ if Set.null remainingKeys
216−
195+ then Map.delete v remainingValues
217−-- | Holds the information about each key: where its new value should come from,
196+ else Map.insert v remainingKeys remainingValues
218−-- and where its old value should go to
197+ case Map.lookup v remainingValues of
219−newtype NodeInfo k (v :: Type) = NodeInfo' { unNodeInfo' :: PM.NodeInfo k (Proxy v) }
198+ Nothing -> return $ NodeInfo (From_Insert v) $ Just undefined -- There's no existing value we can take
221−deriving instance (Show k, Show p) => Show (NodeInfo k p)
200+ if k `Set.member` fromKs
222−deriving instance (Read k, Read p) => Read (NodeInfo k p)
201+ then do
223−deriving instance (Eq k, Eq p) => Eq (NodeInfo k p)
202+ putRemainingKeys $ Set.delete k fromKs
224−deriving instance (Ord k, Ord p) => Ord (NodeInfo k p)
203+ return $ NodeInfo (From_Move k) $ Just undefined -- There's an existing value, and it's here, so no patch necessary
226−{-# COMPLETE NodeInfo #-}
205+ (fromK, remainingKeys) <- return $
227−pattern NodeInfo :: To k -> From k v -> NodeInfo k v
206+ fromMaybe (error "PatchMapWithMove.patchThatChangesMap: impossible: fromKs was empty") $
228−_nodeInfo_to :: NodeInfo k v -> To k
207+ Set.minView fromKs -- There's an existing value, but it's not here; move it here
229−_nodeInfo_from :: NodeInfo k v -> From k v
208+ putRemainingKeys remainingKeys
230−pattern NodeInfo { _nodeInfo_to, _nodeInfo_from } = NodeInfo'
209+ return $ NodeInfo (From_Move fromK) $ Just undefined
231− PM.NodeInfo
210+ Map.traverseWithKey f newByIndex
232− { PM._nodeInfo_to = _nodeInfo_to
211+ unusedOldKeys = fold unusedValuesByValue
233− , PM._nodeInfo_from = Coerce _nodeInfo_from
212+ pointlessMove k = \case
234− }
213+ From_Move k' | k == k' -> True
236−_NodeInfo
215+ keyWasMoved k = if k `Map.member` oldByIndex && not (k `Set.member` unusedOldKeys)
237− :: Iso
216+ then Just undefined
238− (NodeInfo k0 v0)
217+ else Nothing
239− (NodeInfo k1 v1)
218+ 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
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'
220-- | Change the 'From' value of a 'NodeInfo'
263nodeInfoMapFrom :: (From k v -> From k v) -> NodeInfo k v -> NodeInfo k v
221nodeInfoMapFrom :: (From k v -> From k v) -> NodeInfo k v -> NodeInfo k v
264−nodeInfoMapFrom f = coerce $ PM.nodeInfoMapFrom (unFrom' . f . From')
222+nodeInfoMapFrom f ni = ni { _nodeInfo_from = f $ _nodeInfo_from ni }
266-- | Change the 'From' value of a 'NodeInfo', using a 'Functor' (or
224-- | Change the 'From' value of a 'NodeInfo', using a 'Functor' (or
267-- 'Applicative', 'Monad', etc.) action to get the new value
225-- '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)
226+nodeInfoMapMFrom :: Functor f => (From k v -> f (From k v)) -> NodeInfo k v -> f (NodeInfo k v)
272−nodeInfoMapMFrom f = fmap NodeInfo'
227+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'
229-- | Set the 'To' field of a 'NodeInfo'
277nodeInfoSetTo :: To k -> NodeInfo k v -> NodeInfo k v
230nodeInfoSetTo :: To k -> NodeInfo k v -> NodeInfo k v
278−nodeInfoSetTo = coerce . PM.nodeInfoSetTo
231+nodeInfoSetTo to ni = ni { _nodeInfo_to = to }
280−--
233+-- |Helper data structure used for composing patches using the monoid instance.
281−-- From
234+data Fixup k v
282−--
235+ = Fixup_Delete
283−
236+ | Fixup_Update (These (From k v) (To k))
284−-- | Describe how a key's new value should be produced
237+
285−newtype From k (v :: Type) = From' { unFrom' :: PM.From k (Proxy v) }
238+-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
286−
239+instance Ord k => Semigroup (PatchMapWithMove k v) where
287−{-# COMPLETE From_Insert, From_Delete, From_Move #-}
240+ PatchMapWithMove ma <> PatchMapWithMove mb = PatchMapWithMove m
289−-- | Insert the given value here
242+ connections = Map.toList $ Map.intersectionWithKey (\_ a b -> (_nodeInfo_to a, _nodeInfo_from b)) ma mb
290−pattern From_Insert :: v -> From k v
243+ h :: (k, (Maybe k, From k v)) -> [(k, Fixup k v)]
291−pattern From_Insert v = From' (PM.From_Insert v)
244+ h (_, (mToAfter, editBefore)) = case (mToAfter, editBefore) of
292−
245+ (Just toAfter, From_Move fromBefore)
293−-- | Delete the existing value, if any, from here
246+ | fromBefore == toAfter
294−pattern From_Delete :: From k v
247+ -> [(toAfter, Fixup_Delete)]
295−pattern From_Delete = From' PM.From_Delete
248+ | otherwise
296−
249+ -> [ (toAfter, Fixup_Update (This editBefore))
297−-- | Move the value here from the given key
250+ , (fromBefore, Fixup_Update (That mToAfter))
298−pattern From_Move :: k -> From k v
251+ ]
299−pattern From_Move k = From' (PM.From_Move k Proxy)
252+ (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−
253+ (Just toAfter, _) -> [(toAfter, Fixup_Update (This editBefore))]
301−bitraverseFrom
254+ (Nothing, _) -> []
302− :: Applicative f
255+ mergeFixups _ Fixup_Delete Fixup_Delete = Fixup_Delete
303− => (k0 -> f k1)
256+ mergeFixups _ (Fixup_Update a) (Fixup_Update b)
304− -> (v0 -> f v1)
257+ | This x <- a, That y <- b
305− -> From k0 v0 -> f (From k1 v1)
258+ = Fixup_Update $ These x y
306−bitraverseFrom fk fv = fmap From'
259+ | That y <- a, This x <- b
307− . PM.bitraverseFrom fk (\ ~Proxy -> pure Proxy) fv
260+ = Fixup_Update $ These x y
308− . coerce
261+ mergeFixups _ _ _ = error "PatchMapWithMove: incompatible fixups"
309−
262+ fixups = Map.fromListWithKey mergeFixups $ concatMap h connections
310−makeWrapped ''PatchMapWithMove
263+ combineNodeInfos _ nia nib = NodeInfo
311−makeWrapped ''NodeInfo
264+ { _nodeInfo_from = _nodeInfo_from nia
312−makeWrapped ''From
265+ , _nodeInfo_to = _nodeInfo_to nib
267+ applyFixup _ ni = \case
268+ Fixup_Delete -> Nothing
269+ Fixup_Update u -> Just $ NodeInfo
270+ { _nodeInfo_from = fromMaybe (_nodeInfo_from ni) $ getHere u
271+ , _nodeInfo_to = fromMaybe (_nodeInfo_to ni) $ getThere u
273+ m = Map.differenceWithKey applyFixup (Map.unionWithKey combineNodeInfos ma mb) fixups
274+ getHere :: These a b -> Maybe a
279+ getThere :: These a b -> Maybe b
285+--TODO: Figure out how to implement this in terms of PatchDMapWithMove rather than duplicating it here
286+-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
287+instance Ord k => Monoid (PatchMapWithMove k v) where
288+ mempty = PatchMapWithMove mempty