@@ -1,82 +1,151 @@
1−{-# LANGUAGE DeriveFoldable #-}
1+{-# LANGUAGE CPP #-}
2−{-# LANGUAGE DeriveFunctor #-}
3{-# LANGUAGE DeriveTraversable #-}
2{-# LANGUAGE DeriveTraversable #-}
4{-# LANGUAGE FlexibleContexts #-}
3{-# LANGUAGE FlexibleContexts #-}
4+{-# LANGUAGE FlexibleInstances #-}
5+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
5{-# LANGUAGE LambdaCase #-}
6{-# LANGUAGE LambdaCase #-}
7+{-# LANGUAGE MultiParamTypeClasses #-}
6{-# LANGUAGE PatternGuards #-}
8{-# LANGUAGE PatternGuards #-}
9+{-# LANGUAGE PatternSynonyms #-}
7{-# LANGUAGE ScopedTypeVariables #-}
10{-# LANGUAGE ScopedTypeVariables #-}
11+{-# LANGUAGE StandaloneDeriving #-}
12+{-# LANGUAGE TemplateHaskell #-}
13+{-# LANGUAGE TypeApplications #-}
8{-# LANGUAGE TypeFamilies #-}
14{-# LANGUAGE TypeFamilies #-}
15+{-# LANGUAGE ViewPatterns #-}
9-- | 'Patch'es on 'Map' that can insert, delete, and move values from one key to
17-- | 'Patch'es on 'Map' that can insert, delete, and move values from one key to
11−module Data.Patch.MapWithMove where
19+module Data.Patch.MapWithMove
26+ , patchMapWithMoveInsertAll
31+ , unsafePatchMapWithMove
32+ , patchMapWithMoveNewElements
33+ , patchMapWithMoveNewElementsMap
34+ , patchThatSortsMapWith
35+ , patchThatChangesAndSortsMapWith
36+ , patchThatChangesMap
64+import Data.Kind (Type)
13import Data.Patch.Class
65import Data.Patch.Class
66+import Data.Patch.MapWithPatchingMove (PatchMapWithPatchingMove(..), To)
67+import qualified Data.Patch.MapWithPatchingMove as PM -- already a transparent synonym
15−import Control.Arrow
69+import Control.Lens
16−import Control.Monad.Trans.State
19import Data.List
70import Data.List
20import Data.Map (Map)
71import Data.Map (Map)
21import qualified Data.Map as Map
72import qualified Data.Map as Map
22−import Data.Maybe
73+import Data.Proxy
74+#if !MIN_VERSION_base(4,11,0)
23−import Data.Semigroup (Semigroup (..), (<>))
75+import Data.Semigroup (Semigroup (..))
24−import qualified Data.Set as Set
76+#endif
25−import Data.These (These(..))
77+import Data.Traversable (foldMapDefault)
28−-- | Patch a DMap with additions, deletions, and moves. Invariant: If key @k1@
79+-- | Patch a Map with additions, deletions, and moves. Invariant: If key @k1@
29-- is coming from @From_Move k2@, then key @k2@ should be going to @Just k1@,
80-- is coming from @From_Move k2@, then key @k2@ should be going to @Just k1@,
30-- and vice versa. There should never be any unpaired From/To keys.
81-- and vice versa. There should never be any unpaired From/To keys.
31−newtype PatchMapWithMove k v = PatchMapWithMove (Map k (NodeInfo k v)) deriving (Show, Eq, Ord, Functor, Foldable, Traversable)
82+newtype PatchMapWithMove k (v :: Type) = PatchMapWithMove'
32−
83+ { -- | Extract the underlying 'PatchMapWithPatchingMove k (Proxy v)'
33−-- | Holds the information about each key: where its new value should come from,
84+ unPatchMapWithMove' :: PatchMapWithPatchingMove k (Proxy v)
34−-- and where its old value should go to
35−data NodeInfo k v = NodeInfo
36− { _nodeInfo_from :: !(From k v)
37− -- ^ Where do we get the new value for this key?
38− , _nodeInfo_to :: !(To k)
39− -- ^ If the old value is being kept (i.e. moved rather than deleted or
40− -- replaced), where is it going?
42− deriving (Show, Read, Eq, Ord, Functor, Foldable, Traversable)
86+ deriving ( Show, Read, Eq, Ord
87+-- Haddock cannot handle documentation here before GHC 8.6
89+#if __GLASGOW_HASKELL__ >= 806
90+ -- | Compose patches having the same effect as applying the
91+ -- patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p .
44−-- | Describe how a key's new value should be produced
98+pattern Coerce :: Coercible a b => a -> b
45−data From k v
99+pattern Coerce x <- (coerce -> x)
46− = From_Insert v -- ^ Insert the given value here
100+ where Coerce x = coerce x
47− | From_Delete -- ^ Delete the existing value, if any, from here
101+
48− | From_Move !k -- ^ Move the value here from the given key
102+{-# COMPLETE PatchMapWithMove #-}
49− deriving (Show, Read, Eq, Ord, Functor, Foldable, Traversable)
103+pattern PatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
104+-- | Extract the representation of the 'PatchMapWithMove' as a map of
106+unPatchMapWithMove :: PatchMapWithMove k v -> Map k (NodeInfo k v)
107+pattern PatchMapWithMove { unPatchMapWithMove } = PatchMapWithMove' (PatchMapWithPatchingMove (Coerce unPatchMapWithMove))
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
51−-- | Describe where a key's old value will go. If this is 'Just', that means
117+instance Functor (PatchMapWithMove k) where
52−-- the key's old value will be moved to the given other key; if it is 'Nothing',
118+ fmap f = runIdentity . traverse (Identity . f)
53−-- that means it will be deleted.
119+
54−type To = Maybe
120+instance Foldable (PatchMapWithMove k) where
121+ foldMap = foldMapDefault
123+instance Traversable (PatchMapWithMove k) where
129+instance FunctorWithIndex k (PatchMapWithMove k)
130+instance FoldableWithIndex k (PatchMapWithMove k)
131+instance TraversableWithIndex k (PatchMapWithMove k) where
132+ itraverse = itraversed . Indexed
134+ _PatchMapWithMove .>
56-- | Create a 'PatchMapWithMove', validating it
138-- | Create a 'PatchMapWithMove', validating it
57patchMapWithMove :: Ord k => Map k (NodeInfo k v) -> Maybe (PatchMapWithMove k v)
139patchMapWithMove :: Ord k => Map k (NodeInfo k v) -> Maybe (PatchMapWithMove k v)
58−patchMapWithMove m = if valid then Just $ PatchMapWithMove m else Nothing
140+patchMapWithMove = fmap PatchMapWithMove' . PM.patchMapWithPatchingMove . coerce
59− where valid = forwardLinks == backwardLinks
60− forwardLinks = Map.mapMaybe _nodeInfo_to m
61− backwardLinks = Map.fromList $ catMaybes $ flip fmap (Map.toList m) $ \(to, v) ->
62− case _nodeInfo_from v of
63− From_Move from -> Just (from, to)
66-- | Create a 'PatchMapWithMove' that inserts everything in the given 'Map'
142-- | Create a 'PatchMapWithMove' that inserts everything in the given 'Map'
67patchMapWithMoveInsertAll :: Map k v -> PatchMapWithMove k v
143patchMapWithMoveInsertAll :: Map k v -> PatchMapWithMove k v
68−patchMapWithMoveInsertAll m = PatchMapWithMove $ flip fmap m $ \v -> NodeInfo
144+patchMapWithMoveInsertAll = PatchMapWithMove' . PM.patchMapWithPatchingMoveInsertAll
69− { _nodeInfo_from = From_Insert v
70− , _nodeInfo_to = Nothing
73−-- | Extract the internal representation of the 'PatchMapWithMove'
74−unPatchMapWithMove :: PatchMapWithMove k v -> Map k (NodeInfo k v)
75−unPatchMapWithMove (PatchMapWithMove p) = p
77-- | Make a @'PatchMapWithMove' k v@ which has the effect of inserting or updating a value @v@ to the given key @k@, like 'Map.insert'.
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'.
78insertMapKey :: k -> v -> PatchMapWithMove k v
147insertMapKey :: k -> v -> PatchMapWithMove k v
79−insertMapKey k v = PatchMapWithMove . Map.singleton k $ NodeInfo (From_Insert v) Nothing
148+insertMapKey k v = PatchMapWithMove' $ PM.insertMapKey k v
81-- |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:
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:
@@ -84,84 +153,53 @@ insertMapKey k v = PatchMapWithMove . Map.singleton k $ NodeInfo (From_Insert v)
84-- 'Map.delete' src (maybe map ('Map.insert' dst) (Map.lookup src map))
153-- 'Map.delete' src (maybe map ('Map.insert' dst) (Map.lookup src map))
86moveMapKey :: Ord k => k -> k -> PatchMapWithMove k v
155moveMapKey :: Ord k => k -> k -> PatchMapWithMove k v
87−moveMapKey src dst
156+moveMapKey src dst = PatchMapWithMove' $ PM.moveMapKey src dst
88− | src == dst = mempty
90− PatchMapWithMove $ Map.fromList
91− [ (dst, NodeInfo (From_Move src) Nothing)
92− , (src, NodeInfo From_Delete (Just dst))
95-- |Make a @'PatchMapWithMove' k v@ which has the effect of swapping two keys in the mapping, equivalent to:
158-- |Make a @'PatchMapWithMove' k v@ which has the effect of swapping two keys in the mapping, equivalent to:
98-- let aMay = Map.lookup a map
161-- let aMay = Map.lookup a map
99-- bMay = Map.lookup b map
162-- bMay = Map.lookup b map
100−-- in maybe id (Map.insert a) (bMay `mplus` aMay)
163+-- in maybe id (Map.insert a) (bMay <> aMay)
101−-- . maybe id (Map.insert b) (aMay `mplus` bMay)
164+-- . maybe id (Map.insert b) (aMay <> bMay)
102-- . Map.delete a . Map.delete b $ map
165-- . Map.delete a . Map.delete b $ map
104swapMapKey :: Ord k => k -> k -> PatchMapWithMove k v
167swapMapKey :: Ord k => k -> k -> PatchMapWithMove k v
105−swapMapKey src dst
168+swapMapKey src dst = PatchMapWithMove' $ PM.swapMapKey src dst
106− | src == dst = mempty
108− PatchMapWithMove $ Map.fromList
109− [ (dst, NodeInfo (From_Move src) (Just src))
110− , (src, NodeInfo (From_Move dst) (Just dst))
113-- |Make a @'PatchMapWithMove' k v@ which has the effect of deleting a key in the mapping, equivalent to 'Map.delete'.
170-- |Make a @'PatchMapWithMove' k v@ which has the effect of deleting a key in the mapping, equivalent to 'Map.delete'.
114deleteMapKey :: k -> PatchMapWithMove k v
171deleteMapKey :: k -> PatchMapWithMove k v
115−deleteMapKey k = PatchMapWithMove . Map.singleton k $ NodeInfo From_Delete Nothing
172+deleteMapKey = PatchMapWithMove' . PM.deleteMapKey
117-- | Wrap a @'Map' k (NodeInfo k v)@ representing patch changes into a @'PatchMapWithMove' k v@, without checking any invariants.
174-- | Wrap a @'Map' k (NodeInfo k v)@ representing patch changes into a @'PatchMapWithMove' k v@, without checking any invariants.
119-- __Warning:__ when using this function, you must ensure that the invariants of 'PatchMapWithMove' are preserved; they will not be checked.
176-- __Warning:__ when using this function, you must ensure that the invariants of 'PatchMapWithMove' are preserved; they will not be checked.
120unsafePatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
177unsafePatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
121−unsafePatchMapWithMove = PatchMapWithMove
178+unsafePatchMapWithMove = coerce PM.unsafePatchMapWithPatchingMove
123-- | Apply the insertions, deletions, and moves to a given 'Map'
180-- | Apply the insertions, deletions, and moves to a given 'Map'
124instance Ord k => Patch (PatchMapWithMove k v) where
181instance Ord k => Patch (PatchMapWithMove k v) where
125 type PatchTarget (PatchMapWithMove k v) = Map k v
182 type PatchTarget (PatchMapWithMove k v) = Map k v
126− 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?
183+ apply (PatchMapWithMove' p) = apply p
127− where insertions = flip Map.mapMaybeWithKey p $ \_ ni -> case _nodeInfo_from ni of
128− From_Insert v -> Just v
129− From_Move k -> Map.lookup k old
130− From_Delete -> Nothing
131− deletions = flip Map.mapMaybeWithKey p $ \_ ni -> case _nodeInfo_from ni of
132− From_Delete -> Just ()
135-- | Returns all the new elements that will be added to the 'Map'.
185-- | Returns all the new elements that will be added to the 'Map'.
136patchMapWithMoveNewElements :: PatchMapWithMove k v -> [v]
186patchMapWithMoveNewElements :: PatchMapWithMove k v -> [v]
137−patchMapWithMoveNewElements = Map.elems . patchMapWithMoveNewElementsMap
187+patchMapWithMoveNewElements = PM.patchMapWithPatchingMoveNewElements . unPatchMapWithMove'
139-- | Return a @'Map' k v@ with all the inserts/updates from the given @'PatchMapWithMove' k v@.
189-- | Return a @'Map' k v@ with all the inserts/updates from the given @'PatchMapWithMove' k v@.
140patchMapWithMoveNewElementsMap :: PatchMapWithMove k v -> Map k v
190patchMapWithMoveNewElementsMap :: PatchMapWithMove k v -> Map k v
141−patchMapWithMoveNewElementsMap (PatchMapWithMove p) = Map.mapMaybe f p
191+patchMapWithMoveNewElementsMap = PM.patchMapWithPatchingMoveNewElementsMap . unPatchMapWithMove'
142− where f ni = case _nodeInfo_from ni of
143− From_Insert v -> Just v
144− From_Move _ -> Nothing
145− From_Delete -> Nothing
147-- | Create a 'PatchMapWithMove' that, if applied to the given 'Map', will sort
193-- | Create a 'PatchMapWithMove' that, if applied to the given 'Map', will sort
148-- its values using the given ordering function. The set keys of the 'Map' is
194-- its values using the given ordering function. The set keys of the 'Map' is
149-- not changed.
195-- not changed.
150patchThatSortsMapWith :: Ord k => (v -> v -> Ordering) -> Map k v -> PatchMapWithMove k v
196patchThatSortsMapWith :: Ord k => (v -> v -> Ordering) -> Map k v -> PatchMapWithMove k v
151−patchThatSortsMapWith cmp m = PatchMapWithMove $ Map.fromList $ catMaybes $ zipWith g unsorted sorted
197+patchThatSortsMapWith cmp = PatchMapWithMove' . PM.patchThatSortsMapWith cmp
152− where unsorted = Map.toList m
153− sorted = sortBy (cmp `on` snd) unsorted
154− f (to, _) (from, _) = if to == from then Nothing else
156− reverseMapping = Map.fromList $ catMaybes $ zipWith f unsorted sorted
157− g (to, _) (from, _) = if to == from then Nothing else
158− let Just movingTo = Map.lookup to reverseMapping
159− in Just (to, NodeInfo (From_Move from) $ Just movingTo)
161-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
199-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
162-- will produce a 'Map' with the same values as the second 'Map' but with the
200-- will produce a 'Map' with the same values as the second 'Map' but with the
163-- values sorted with the given ordering function.
201-- values sorted with the given ordering function.
164−patchThatChangesAndSortsMapWith :: forall k v. (Ord k, Ord v) => (v -> v -> Ordering) -> Map k v -> Map k v -> PatchMapWithMove k v
202+patchThatChangesAndSortsMapWith :: (Ord k, Ord v) => (v -> v -> Ordering) -> Map k v -> Map k v -> PatchMapWithMove k v
165patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatChangesMap oldByIndex newByIndex
203patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatChangesMap oldByIndex newByIndex
166 where newList = Map.toList newByIndexUnsorted
204 where newList = Map.toList newByIndexUnsorted
167 newByIndex = Map.fromList $ zip (fst <$> newList) $ sortBy cmp $ snd <$> newList
205 newByIndex = Map.fromList $ zip (fst <$> newList) $ sortBy cmp $ snd <$> newList
@@ -169,102 +207,106 @@ patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatCha
169-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
207-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
170-- will produce the second 'Map'.
208-- will produce the second 'Map'.
171patchThatChangesMap :: (Ord k, Ord v) => Map k v -> Map k v -> PatchMapWithMove k v
209patchThatChangesMap :: (Ord k, Ord v) => Map k v -> Map k v -> PatchMapWithMove k v
172−patchThatChangesMap oldByIndex newByIndex = patch
210+patchThatChangesMap oldByIndex newByIndex = PatchMapWithMove' $
173− where oldByValue = Map.fromListWith Set.union $ swap . first Set.singleton <$> Map.toList oldByIndex
211+ PM.patchThatChangesMap oldByIndex newByIndex
174− (insertsAndMoves, unusedValuesByValue) = flip runState oldByValue $ do
212+
175− let f k v = do
213+--
176− remainingValues <- get
214+-- NodeInfo
177− let putRemainingKeys remainingKeys = put $ if Set.null remainingKeys
215+--
178− then Map.delete v remainingValues
216+
179− else Map.insert v remainingKeys remainingValues
217+-- | Holds the information about each key: where its new value should come from,
180− case Map.lookup v remainingValues of
218+-- and where its old value should go to
181− Nothing -> return $ NodeInfo (From_Insert v) $ Just undefined -- There's no existing value we can take
219+newtype NodeInfo k (v :: Type) = NodeInfo' { unNodeInfo' :: PM.NodeInfo k (Proxy v) }
183− if k `Set.member` fromKs
221+deriving instance (Show k, Show p) => Show (NodeInfo k p)
184− then do
222+deriving instance (Read k, Read p) => Read (NodeInfo k p)
185− putRemainingKeys $ Set.delete k fromKs
223+deriving instance (Eq k, Eq p) => Eq (NodeInfo k p)
186− return $ NodeInfo (From_Move k) $ Just undefined -- There's an existing value, and it's here, so no patch necessary
224+deriving instance (Ord k, Ord p) => Ord (NodeInfo k p)
188− (fromK, remainingKeys) <- return . fromJust $ Set.minView fromKs -- There's an existing value, but it's not here; move it here
226+{-# COMPLETE NodeInfo #-}
189− putRemainingKeys remainingKeys
227+pattern NodeInfo :: To k -> From k v -> NodeInfo k v
190− return $ NodeInfo (From_Move fromK) $ Just undefined
228+_nodeInfo_to :: NodeInfo k v -> To k
191− Map.traverseWithKey f newByIndex
229+_nodeInfo_from :: NodeInfo k v -> From k v
192− unusedOldKeys = fold unusedValuesByValue
230+pattern NodeInfo { _nodeInfo_to, _nodeInfo_from } = NodeInfo'
193− pointlessMove k = \case
231+ PM.NodeInfo
194− From_Move k' | k == k' -> True
232+ { PM._nodeInfo_to = _nodeInfo_to
195− _ -> False
233+ , PM._nodeInfo_from = Coerce _nodeInfo_from
196− keyWasMoved k = if k `Map.member` oldByIndex && not (k `Set.member` unusedOldKeys)
234+ }
197− then Just undefined
235+
198− else Nothing
236+_NodeInfo
199− 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
237+ :: Iso
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
201-- | Change the 'From' value of a 'NodeInfo'
262-- | Change the 'From' value of a 'NodeInfo'
202nodeInfoMapFrom :: (From k v -> From k v) -> NodeInfo k v -> NodeInfo k v
263nodeInfoMapFrom :: (From k v -> From k v) -> NodeInfo k v -> NodeInfo k v
203−nodeInfoMapFrom f ni = ni { _nodeInfo_from = f $ _nodeInfo_from ni }
264+nodeInfoMapFrom f = coerce $ PM.nodeInfoMapFrom (unFrom' . f . From')
205-- | Change the 'From' value of a 'NodeInfo', using a 'Functor' (or
266-- | Change the 'From' value of a 'NodeInfo', using a 'Functor' (or
206-- 'Applicative', 'Monad', etc.) action to get the new value
267-- 'Applicative', 'Monad', etc.) action to get the new value
270+ => (From k v -> f (From k v))
207−nodeInfoMapMFrom :: Functor f => (From k v -> f (From k v)) -> NodeInfo k v -> f (NodeInfo k v)
271+ -> NodeInfo k v -> f (NodeInfo k v)
208−nodeInfoMapMFrom f ni = fmap (\result -> ni { _nodeInfo_from = result }) $ f $ _nodeInfo_from ni
272+nodeInfoMapMFrom f = fmap NodeInfo'
273+ . PM.nodeInfoMapMFrom (fmap unFrom' . f . From')
210-- | Set the 'To' field of a 'NodeInfo'
276-- | Set the 'To' field of a 'NodeInfo'
211nodeInfoSetTo :: To k -> NodeInfo k v -> NodeInfo k v
277nodeInfoSetTo :: To k -> NodeInfo k v -> NodeInfo k v
212−nodeInfoSetTo to ni = ni { _nodeInfo_to = to }
278+nodeInfoSetTo = coerce . PM.nodeInfoSetTo
214−-- |Helper data structure used for composing patches using the monoid instance.
280+--
215−data Fixup k v
281+-- From
216− = Fixup_Delete
282+--
217− | Fixup_Update (These (From k v) (To k))
283+
218−
284+-- | Describe how a key's new value should be produced
219−-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
285+newtype From k (v :: Type) = From' { unFrom' :: PM.From k (Proxy v) }
220−instance Ord k => Semigroup (PatchMapWithMove k v) where
286+
221− PatchMapWithMove ma <> PatchMapWithMove mb = PatchMapWithMove m
287+{-# COMPLETE From_Insert, From_Delete, From_Move #-}
223− connections = Map.toList $ Map.intersectionWithKey (\_ a b -> (_nodeInfo_to a, _nodeInfo_from b)) ma mb
289+-- | Insert the given value here
224− h :: (k, (Maybe k, From k v)) -> [(k, Fixup k v)]
290+pattern From_Insert :: v -> From k v
225− h (_, (mToAfter, editBefore)) = case (mToAfter, editBefore) of
291+pattern From_Insert v = From' (PM.From_Insert v)
226− (Just toAfter, From_Move fromBefore)
292+
227− | fromBefore == toAfter
293+-- | Delete the existing value, if any, from here
228− -> [(toAfter, Fixup_Delete)]
294+pattern From_Delete :: From k v
229− | otherwise
295+pattern From_Delete = From' PM.From_Delete
230− -> [ (toAfter, Fixup_Update (This editBefore))
296+
231− , (fromBefore, Fixup_Update (That mToAfter))
297+-- | Move the value here from the given key
232− ]
298+pattern From_Move :: k -> From k v
233− (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
299+pattern From_Move k = From' (PM.From_Move k Proxy)
234− (Just toAfter, _) -> [(toAfter, Fixup_Update (This editBefore))]
300+
235− (Nothing, _) -> []
301+bitraverseFrom
236− mergeFixups _ Fixup_Delete Fixup_Delete = Fixup_Delete
302+ :: Applicative f
237− mergeFixups _ (Fixup_Update a) (Fixup_Update b)
303+ => (k0 -> f k1)
238− | This x <- a, That y <- b
304+ -> (v0 -> f v1)
239− = Fixup_Update $ These x y
305+ -> From k0 v0 -> f (From k1 v1)
240− | That y <- a, This x <- b
306+bitraverseFrom fk fv = fmap From'
241− = Fixup_Update $ These x y
307+ . PM.bitraverseFrom fk (\ ~Proxy -> pure Proxy) fv
242− mergeFixups _ _ _ = error "PatchMapWithMove: incompatible fixups"
308+ . coerce
243− fixups = Map.fromListWithKey mergeFixups $ concatMap h connections
309+
244− combineNodeInfos _ nia nib = NodeInfo
310+makeWrapped ''PatchMapWithMove
245− { _nodeInfo_from = _nodeInfo_from nia
311+makeWrapped ''NodeInfo
246− , _nodeInfo_to = _nodeInfo_to nib
312+makeWrapped ''From
248− applyFixup _ ni = \case
249− Fixup_Delete -> Nothing
250− Fixup_Update u -> Just $ NodeInfo
251− { _nodeInfo_from = fromMaybe (_nodeInfo_from ni) $ getHere u
252− , _nodeInfo_to = fromMaybe (_nodeInfo_to ni) $ getThere u
254− m = Map.differenceWithKey applyFixup (Map.unionWithKey combineNodeInfos ma mb) fixups
255− getHere :: These a b -> Maybe a
260− getThere :: These a b -> Maybe b
266−--TODO: Figure out how to implement this in terms of PatchDMapWithMove rather than duplicating it here
267−-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
268−instance Ord k => Monoid (PatchMapWithMove k v) where
269− mempty = PatchMapWithMove mempty