@@ -1,312 +1,324 @@
1{-# LANGUAGE CPP #-}
1{-# LANGUAGE CPP #-}
2−{-# LANGUAGE DeriveTraversable #-}
3{-# LANGUAGE FlexibleContexts #-}
2{-# LANGUAGE FlexibleContexts #-}
4−{-# LANGUAGE FlexibleInstances #-}
5−{-# LANGUAGE GeneralizedNewtypeDeriving #-}
6{-# LANGUAGE LambdaCase #-}
3{-# LANGUAGE LambdaCase #-}
7−{-# LANGUAGE MultiParamTypeClasses #-}
8{-# LANGUAGE PatternGuards #-}
4{-# LANGUAGE PatternGuards #-}
9−{-# LANGUAGE PatternSynonyms #-}
10{-# LANGUAGE ScopedTypeVariables #-}
5{-# LANGUAGE ScopedTypeVariables #-}
11{-# LANGUAGE StandaloneDeriving #-}
6{-# LANGUAGE StandaloneDeriving #-}
12−{-# LANGUAGE TemplateHaskell #-}
13−{-# LANGUAGE TypeApplications #-}
14{-# LANGUAGE TypeFamilies #-}
7{-# LANGUAGE TypeFamilies #-}
15−{-# LANGUAGE ViewPatterns #-}
8+{-# LANGUAGE UndecidableInstances #-}
17-- | 'Patch'es on 'Map' that can insert, delete, and move values from one key to
9-- | 'Patch'es on 'Map' that can insert, delete, and move values from one key to
19−module Data.Patch.MapWithMove
11+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
13import 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
15+import Control.Arrow
16+import Control.Monad.Trans.State
70import Data.List
19import Data.List
71import Data.Map (Map)
20import Data.Map (Map)
72import qualified Data.Map as Map
21import qualified Data.Map as Map
73−import Data.Proxy
22+import Data.Maybe
74−#if !MIN_VERSION_base(4,11,0)
23+#if !MIN_VERSION_base(4,9,0)
75−import Data.Semigroup (Semigroup (..))
24+import Data.Semigroup (Semigroup (..), (<>))
77−import Data.Traversable (foldMapDefault)
26+import Data.Monoid.DecidablyEmpty
27+import qualified Data.Set as Set
28+import Data.These (These (..))
79-- | Patch a Map with additions, deletions, and moves. Invariant: If key @k1@
31-- | 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@,
32-- 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.
33-- and vice versa. There should never be any unpaired From/To keys.
82−newtype PatchMapWithMove k (v :: Type) = PatchMapWithMove'
34+newtype PatchMapWithMove k p = PatchMapWithMove (Map k (NodeInfo k p))
83− { -- | Extract the underlying 'PatchMapWithPatchingMove k (Proxy v)'
35+deriving instance (Show k, Show p, Show (PatchTarget p)) => Show (PatchMapWithMove k p)
84− unPatchMapWithMove' :: PatchMapWithPatchingMove k (Proxy v)
36+deriving instance (Eq k, Eq p, Eq (PatchTarget p)) => Eq (PatchMapWithMove k p)
85− }
37+deriving instance (Ord k, Ord p, Ord (PatchTarget p)) => Ord (PatchMapWithMove k p)
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 .
98−pattern Coerce :: Coercible a b => a -> b
39+-- | Holds the information about each key: where its new value should come from,
99−pattern Coerce x <- (coerce -> x)
40+-- and where its old value should go to
100− where Coerce x = coerce x
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'.
41+data NodeInfo k p = NodeInfo
106−unPatchMapWithMove :: PatchMapWithMove k v -> Map k (NodeInfo k v)
42+ { _nodeInfo_from :: !(From k p)
107−pattern PatchMapWithMove { unPatchMapWithMove } = PatchMapWithMove' (PatchMapWithPatchingMove (Coerce unPatchMapWithMove))
43+ -- ^ Where do we get the new value for this key?
108−
44+ , _nodeInfo_to :: !(To k)
109−_PatchMapWithMove
45+ -- ^ If the old value is being kept (i.e. moved rather than deleted or
110− :: Iso
46+ -- replaced), where is it going?
111− (PatchMapWithMove k0 v0)
47+ }
112− (PatchMapWithMove k1 v1)
48+deriving instance (Show k, Show p, Show (PatchTarget p)) => Show (NodeInfo k p)
113− (Map k0 (NodeInfo k0 v0))
49+deriving instance (Read k, Read p, Read (PatchTarget p)) => Read (NodeInfo k p)
114− (Map k1 (NodeInfo k1 v1))
50+deriving instance (Eq k, Eq p, Eq (PatchTarget p)) => Eq (NodeInfo k p)
115−_PatchMapWithMove = iso unPatchMapWithMove PatchMapWithMove
51+deriving instance (Ord k, Ord p, Ord (PatchTarget p)) => Ord (NodeInfo k p)
117−instance Functor (PatchMapWithMove k) where
118− fmap f = runIdentity . traverse (Identity . f)
120−instance Foldable (PatchMapWithMove k) where
53+-- | Describe how a key's new value should be produced
121− foldMap = foldMapDefault
54+data From k p
55+ = From_Insert (PatchTarget p) -- ^ Insert the given value here
56+ | From_Delete -- ^ Delete the existing value, if any, from here
57+ | From_Move !k !p -- ^ Move the value here from the given key, and apply the given patch
123−instance Traversable (PatchMapWithMove k) where
59+deriving instance (Show k, Show p, Show (PatchTarget p)) => Show (From k p)
124− traverse =
60+deriving instance (Read k, Read p, Read (PatchTarget p)) => Read (From k p)
125− _PatchMapWithMove .
61+deriving instance (Eq k, Eq p, Eq (PatchTarget p)) => Eq (From k p)
126− traverse .
62+deriving instance (Ord k, Ord p, Ord (PatchTarget p)) => Ord (From k p)
129−instance FunctorWithIndex k (PatchMapWithMove k)
64+-- | Describe where a key's old value will go. If this is 'Just', that means
130−instance FoldableWithIndex k (PatchMapWithMove k)
65+-- the key's old value will be moved to the given other key; if it is 'Nothing',
131−instance TraversableWithIndex k (PatchMapWithMove k) where
66+-- that means it will be deleted.
132− itraverse = itraversed . Indexed
67+type To = Maybe
134− _PatchMapWithMove .>
138-- | Create a 'PatchMapWithMove', validating it
69-- | Create a 'PatchMapWithMove', validating it
139−patchMapWithMove :: Ord k => Map k (NodeInfo k v) -> Maybe (PatchMapWithMove k v)
71+ :: Ord k => Map k (NodeInfo k p) -> Maybe (PatchMapWithMove k p)
140−patchMapWithMove = fmap PatchMapWithMove' . PM.patchMapWithPatchingMove . coerce
72+patchMapWithMove m = if valid then Just $ PatchMapWithMove m else Nothing
73+ where valid = forwardLinks == backwardLinks
74+ forwardLinks = Map.mapMaybe _nodeInfo_to m
75+ backwardLinks = Map.fromList $ catMaybes $ flip fmap (Map.toList m) $ \(to, p) ->
76+ case _nodeInfo_from p of
77+ From_Move from _ -> Just (from, to)
142-- | Create a 'PatchMapWithMove' that inserts everything in the given 'Map'
80-- | Create a 'PatchMapWithMove' that inserts everything in the given 'Map'
143−patchMapWithMoveInsertAll :: Map k v -> PatchMapWithMove k v
81+patchMapWithMoveInsertAll
82+ :: Map k (PatchTarget p) -> PatchMapWithMove k p
144−patchMapWithMoveInsertAll = PatchMapWithMove' . PM.patchMapWithPatchingMoveInsertAll
83+patchMapWithMoveInsertAll m = PatchMapWithMove $ flip fmap m $ \v -> NodeInfo
84+ { _nodeInfo_from = From_Insert v
85+ , _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'.
88+-- | Extract the internal representation of the 'PatchMapWithMove'
147−insertMapKey :: k -> v -> PatchMapWithMove k v
89+unPatchMapWithMove
148−insertMapKey k v = PatchMapWithMove' $ PM.insertMapKey k v
90+ :: PatchMapWithMove k p -> Map k (NodeInfo k p)
91+unPatchMapWithMove (PatchMapWithMove p) = p
93+-- | Make a @'PatchMapWithMove' k p@ which has the effect of inserting or updating a value @v@ to the given key @k@, like 'Map.insert'.
95+ :: k -> PatchTarget p -> PatchMapWithMove k p
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 p@ which has the effect of moving the value from the first key @k@ to the second key @k@, equivalent to:
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))
155−moveMapKey :: Ord k => k -> k -> PatchMapWithMove k v
104+ :: (DecidablyEmpty p, Patch p) => Ord k => k -> k -> PatchMapWithMove k p
156−moveMapKey src dst = PatchMapWithMove' $ PM.moveMapKey src dst
105+moveMapKey src dst
157−
106+ | src == dst = mempty
108+ PatchMapWithMove $ Map.fromList
109+ [ (dst, NodeInfo (From_Move src mempty) Nothing)
110+ , (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:
113+-- |Make a @'PatchMapWithMove' k p@ which has the effect of swapping two keys in the mapping, equivalent to:
161-- let aMay = Map.lookup a map
116-- let aMay = Map.lookup a map
162-- bMay = Map.lookup b map
117-- bMay = Map.lookup b map
163−-- in maybe id (Map.insert a) (bMay <> aMay)
118+-- in maybe id (Map.insert a) (bMay `mplus` aMay)
164−-- . maybe id (Map.insert b) (aMay <> bMay)
119+-- . maybe id (Map.insert b) (aMay `mplus` bMay)
165-- . Map.delete a . Map.delete b $ map
120-- . Map.delete a . Map.delete b $ map
167−swapMapKey :: Ord k => k -> k -> PatchMapWithMove k v
123+ :: (DecidablyEmpty p, Patch p) => Ord k => k -> k -> PatchMapWithMove k p
168−swapMapKey src dst = PatchMapWithMove' $ PM.swapMapKey src dst
124+swapMapKey src dst
125+ | src == dst = mempty
127+ PatchMapWithMove $ Map.fromList
128+ [ (dst, NodeInfo (From_Move src mempty) (Just src))
129+ , (src, NodeInfo (From_Move dst mempty) (Just dst))
170-- |Make a @'PatchMapWithMove' k v@ which has the effect of deleting a key in the mapping, equivalent to 'Map.delete'.
132-- |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
134+ :: k -> PatchMapWithMove k v
172−deleteMapKey = PatchMapWithMove' . PM.deleteMapKey
135+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.
137-- | 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.
139-- __Warning:__ when using this function, you must ensure that the invariants of 'PatchMapWithMove' are preserved; they will not be checked.
140+unsafePatchMapWithMove
177−unsafePatchMapWithMove :: Map k (NodeInfo k v) -> PatchMapWithMove k v
141+ :: Map k (NodeInfo k p) -> PatchMapWithMove k p
178−unsafePatchMapWithMove = coerce PM.unsafePatchMapWithPatchingMove
142+unsafePatchMapWithMove = PatchMapWithMove
180-- | Apply the insertions, deletions, and moves to a given 'Map'
144-- | Apply the insertions, deletions, and moves to a given 'Map'
181−instance Ord k => Patch (PatchMapWithMove k v) where
145+instance (Ord k, Patch p) => PatchHet (PatchMapWithMove k p) where
182− type PatchTarget (PatchMapWithMove k v) = Map k v
146+ type PatchSource (PatchMapWithMove k p) = Map k (PatchSource p)
183− apply (PatchMapWithMove' p) = apply p
147+ type PatchTarget (PatchMapWithMove k p) = Map k (PatchTarget p)
184−
148+instance (Ord k, Patch p) => Patch (PatchMapWithMove k p) where
149+ -- TODO: return Nothing sometimes
150+ -- Note: the strict application here is critical to ensuring that incremental
151+ -- merges don't hold onto all their prerequisite events forever; can we make
152+ -- this more robust?
153+ apply (PatchMapWithMove m) old = Just $! insertions `Map.union` (old `Map.difference` deletions)
154+ where insertions = flip Map.mapMaybeWithKey m $ \_ ni -> case _nodeInfo_from ni of
155+ From_Insert v -> Just v
156+ From_Move k p -> applyAlways p <$> Map.lookup k old
157+ From_Delete -> Nothing
158+ deletions = flip Map.mapMaybeWithKey m $ \_ ni -> case _nodeInfo_from ni of
159+ From_Delete -> Just ()
185−-- | Returns all the new elements that will be added to the 'Map'.
162+-- | Returns all the new elements that will be added to the 'Map'
186−patchMapWithMoveNewElements :: PatchMapWithMove k v -> [v]
163+patchMapWithMoveNewElements
187−patchMapWithMoveNewElements = PM.patchMapWithPatchingMoveNewElements . unPatchMapWithMove'
164+ :: PatchMapWithMove k p -> [PatchTarget p]
165+patchMapWithMoveNewElements = Map.elems . patchMapWithMoveNewElementsMap
189-- | Return a @'Map' k v@ with all the inserts/updates from the given @'PatchMapWithMove' k v@.
167-- | Return a @'Map' k v@ with all the inserts/updates from the given @'PatchMapWithMove' k v@.
190−patchMapWithMoveNewElementsMap :: PatchMapWithMove k v -> Map k v
168+patchMapWithMoveNewElementsMap
169+ :: PatchMapWithMove k p -> Map k (PatchTarget p)
191−patchMapWithMoveNewElementsMap = PM.patchMapWithPatchingMoveNewElementsMap . unPatchMapWithMove'
170+patchMapWithMoveNewElementsMap (PatchMapWithMove p) = Map.mapMaybe f p
171+ where f ni = case _nodeInfo_from ni of
172+ From_Insert v -> Just v
173+ From_Move _ _ -> Nothing
174+ From_Delete -> Nothing
193-- | Create a 'PatchMapWithMove' that, if applied to the given 'Map', will sort
176-- | 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
177-- its values using the given ordering function. The set keys of the 'Map' is
195-- not changed.
178-- not changed.
196−patchThatSortsMapWith :: Ord k => (v -> v -> Ordering) -> Map k v -> PatchMapWithMove k v
179+patchThatSortsMapWith
180+ :: (Ord k, Monoid p)
181+ => (PatchTarget p -> PatchTarget p -> Ordering)
182+ -> Map k (PatchTarget p) -> PatchMapWithMove k p
197−patchThatSortsMapWith cmp = PatchMapWithMove' . PM.patchThatSortsMapWith cmp
183+patchThatSortsMapWith cmp m = PatchMapWithMove $ Map.fromList $ catMaybes $ zipWith g unsorted sorted
184+ where unsorted = Map.toList m
185+ sorted = sortBy (cmp `on` snd) unsorted
186+ f (to, _) (from, _) = if to == from then Nothing else
188+ reverseMapping = Map.fromList $ catMaybes $ zipWith f unsorted sorted
189+ g (to, _) (from, _) = if to == from then Nothing else
190+ let Just movingTo = Map.lookup from reverseMapping
191+ in Just (to, NodeInfo (From_Move from mempty) $ Just movingTo)
199-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
193-- | 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
194-- will produce a 'Map' with the same values as the second 'Map' but with the
201-- values sorted with the given ordering function.
195-- 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
196+patchThatChangesAndSortsMapWith
197+ :: forall k p. (Ord k, Ord (PatchTarget p), Monoid p)
198+ => (PatchTarget p -> PatchTarget p -> Ordering)
199+ -> Map k (PatchTarget p) -> Map k (PatchTarget p) -> PatchMapWithMove k p
203patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatChangesMap oldByIndex newByIndex
200patchThatChangesAndSortsMapWith cmp oldByIndex newByIndexUnsorted = patchThatChangesMap oldByIndex newByIndex
204 where newList = Map.toList newByIndexUnsorted
201 where newList = Map.toList newByIndexUnsorted
205 newByIndex = Map.fromList $ zip (fst <$> newList) $ sortBy cmp $ snd <$> newList
202 newByIndex = Map.fromList $ zip (fst <$> newList) $ sortBy cmp $ snd <$> newList
207-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
204-- | Create a 'PatchMapWithMove' that, if applied to the first 'Map' provided,
208-- will produce the second 'Map'.
205-- will produce the second 'Map'.
209−patchThatChangesMap :: (Ord k, Ord v) => Map k v -> Map k v -> PatchMapWithMove k v
206+patchThatChangesMap
207+ :: (Ord k, Ord (PatchTarget p), Monoid p)
208+ => Map k (PatchTarget p) -> Map k (PatchTarget p) -> PatchMapWithMove k p
210−patchThatChangesMap oldByIndex newByIndex = PatchMapWithMove' $
209+patchThatChangesMap oldByIndex newByIndex = patch
211− PM.patchThatChangesMap oldByIndex newByIndex
210+ where oldByValue = Map.fromListWith Set.union $ swap . first Set.singleton <$> Map.toList oldByIndex
212−
211+ (insertsAndMoves, unusedValuesByValue) = flip runState oldByValue $ do
213−--
212+ let f k v = do
214−-- NodeInfo
213+ remainingValues <- get
215−--
214+ let putRemainingKeys remainingKeys = put $ if Set.null remainingKeys
216−
215+ then Map.delete v remainingValues
217−-- | Holds the information about each key: where its new value should come from,
216+ else Map.insert v remainingKeys remainingValues
218−-- and where its old value should go to
217+ case Map.lookup v remainingValues of
219−newtype NodeInfo k (v :: Type) = NodeInfo' { unNodeInfo' :: PM.NodeInfo k (Proxy v) }
218+ 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)
220+ if k `Set.member` fromKs
222−deriving instance (Read k, Read p) => Read (NodeInfo k p)
221+ then do
223−deriving instance (Eq k, Eq p) => Eq (NodeInfo k p)
222+ putRemainingKeys $ Set.delete k fromKs
224−deriving instance (Ord k, Ord p) => Ord (NodeInfo k p)
223+ return $ NodeInfo (From_Move k mempty) $ Just undefined -- There's an existing value, and it's here, so no patch necessary
226−{-# COMPLETE NodeInfo #-}
225+ (fromK, remainingKeys) <- return . fromJust $ Set.minView fromKs -- There's an existing value, but it's not here; move it here
227−pattern NodeInfo :: To k -> From k v -> NodeInfo k v
226+ putRemainingKeys remainingKeys
228−_nodeInfo_to :: NodeInfo k v -> To k
227+ return $ NodeInfo (From_Move fromK mempty) $ Just undefined
229−_nodeInfo_from :: NodeInfo k v -> From k v
228+ Map.traverseWithKey f newByIndex
230−pattern NodeInfo { _nodeInfo_to, _nodeInfo_from } = NodeInfo'
229+ unusedOldKeys = fold unusedValuesByValue
231− PM.NodeInfo
230+ pointlessMove k = \case
232− { PM._nodeInfo_to = _nodeInfo_to
231+ From_Move k' _ | k == k' -> True
233− , PM._nodeInfo_from = Coerce _nodeInfo_from
232+ _ -> False
234− }
233+ keyWasMoved k = if k `Map.member` oldByIndex && not (k `Set.member` unusedOldKeys)
235−
234+ then Just undefined
236−_NodeInfo
235+ else Nothing
237− :: Iso
236+ 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'
238-- | Change the 'From' value of a 'NodeInfo'
263−nodeInfoMapFrom :: (From k v -> From k v) -> NodeInfo k v -> NodeInfo k v
240+ :: (From k v -> From k v) -> NodeInfo k v -> NodeInfo k v
264−nodeInfoMapFrom f = coerce $ PM.nodeInfoMapFrom (unFrom' . f . From')
241+nodeInfoMapFrom f ni = ni { _nodeInfo_from = f $ _nodeInfo_from ni }
266-- | Change the 'From' value of a 'NodeInfo', using a 'Functor' (or
243-- | Change the 'From' value of a 'NodeInfo', using a 'Functor' (or
267-- 'Applicative', 'Monad', etc.) action to get the new value
244-- 'Applicative', 'Monad', etc.) action to get the new value
268nodeInfoMapMFrom
245nodeInfoMapMFrom
270− => (From k v -> f (From k v))
271− -> NodeInfo k v -> f (NodeInfo k v)
246+ :: Functor f => (From k v -> f (From k v)) -> NodeInfo k v -> f (NodeInfo k v)
272−nodeInfoMapMFrom f = fmap NodeInfo'
247+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'
249-- | Set the 'To' field of a 'NodeInfo'
277−nodeInfoSetTo :: To k -> NodeInfo k v -> NodeInfo k v
251+ :: To k -> NodeInfo k v -> NodeInfo k v
278−nodeInfoSetTo = coerce . PM.nodeInfoSetTo
252+nodeInfoSetTo to ni = ni { _nodeInfo_to = to }
280−--
254+-- |Helper data structure used for composing patches using the monoid instance.
281−-- From
255+data Fixup k v
282−--
256+ = Fixup_Delete
283−
257+ | Fixup_Update (These (From k v) (To k))
284−-- | Describe how a key's new value should be produced
258+
285−newtype From k (v :: Type) = From' { unFrom' :: PM.From k (Proxy v) }
259+-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
287−{-# COMPLETE From_Insert, From_Delete, From_Move #-}
261+ , Monoid p
288−
262+ , DecidablyEmpty p
289−-- | Insert the given value here
263+ , Patch p
290−pattern From_Insert :: v -> From k v
264+ ) => Semigroup (PatchMapWithMove k p) where
291−pattern From_Insert v = From' (PM.From_Insert v)
265+ PatchMapWithMove ma <> PatchMapWithMove mb = PatchMapWithMove m
293−-- | Delete the existing value, if any, from here
267+ connections = Map.toList $ Map.intersectionWithKey (\_ a b -> (_nodeInfo_to a, _nodeInfo_from b)) ma mb
294−pattern From_Delete :: From k v
268+ h :: (k, (Maybe k, From k p)) -> [(k, Fixup k p)]
295−pattern From_Delete = From' PM.From_Delete
269+ h (_, (mToAfter, editBefore)) = case (mToAfter, editBefore) of
296−
270+ (Just toAfter, From_Move fromBefore p)
297−-- | Move the value here from the given key
271+ | fromBefore == toAfter && isNull p
298−pattern From_Move :: k -> From k v
272+ -> [(toAfter, Fixup_Delete)]
299−pattern From_Move k = From' (PM.From_Move k Proxy)
273+ | otherwise
300−
274+ -> [ (toAfter, Fixup_Update (This editBefore))
301−bitraverseFrom
275+ , (fromBefore, Fixup_Update (That mToAfter))
302− :: Applicative f
276+ ]
303− => (k0 -> f k1)
277+ (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
304− -> (v0 -> f v1)
278+ (Just toAfter, _) -> [(toAfter, Fixup_Update (This editBefore))]
305− -> From k0 v0 -> f (From k1 v1)
279+ (Nothing, _) -> []
306−bitraverseFrom fk fv = fmap From'
280+ mergeFixups _ Fixup_Delete Fixup_Delete = Fixup_Delete
307− . PM.bitraverseFrom fk (\ ~Proxy -> pure Proxy) fv
281+ mergeFixups _ (Fixup_Update a) (Fixup_Update b)
308− . coerce
282+ | This x <- a, That y <- b
309−
283+ = Fixup_Update $ These x y
284+ | That y <- a, This x <- b
285+ = Fixup_Update $ These x y
286+ mergeFixups _ _ _ = error "PatchMapWithMove: incompatible fixups"
287+ fixups = Map.fromListWithKey mergeFixups $ concatMap h connections
288+ combineNodeInfos _ nia nib = NodeInfo
289+ { _nodeInfo_from = _nodeInfo_from nia
290+ , _nodeInfo_to = _nodeInfo_to nib
292+ applyFixup _ ni = \case
293+ Fixup_Delete -> Nothing
294+ Fixup_Update u -> Just $ NodeInfo
295+ { _nodeInfo_from = case _nodeInfo_from ni of
296+ f@(From_Move _ p') -> case getHere u of -- The `from` fixup comes from the "old" patch
297+ Nothing -> f -- If there's no `from` fixup, just use the "new" `from`
298+ Just (From_Insert v) -> From_Insert $ applyAlways p' v
299+ Just From_Delete -> From_Delete
300+ Just (From_Move oldKey p) -> From_Move oldKey $ p' <> p
301+ _ -> error "PatchMapWithMove: fixup for non-move From"
302+ , _nodeInfo_to = fromMaybe (_nodeInfo_to ni) $ getThere u
304+ m = Map.differenceWithKey applyFixup (Map.unionWithKey combineNodeInfos ma mb) fixups
305+ getHere :: These a b -> Maybe a
310+ getThere :: These a b -> Maybe b
316+--TODO: Figure out how to implement this in terms of PatchDMapWithMove rather than duplicating it here
317+-- |Compose patches having the same effect as applying the patches in turn: @'applyAlways' (p <> q) == 'applyAlways' p . 'applyAlways' q@
322+ ) => Monoid (PatchMapWithMove k p) where
310−makeWrapped ''PatchMapWithMove
323+ mempty = PatchMapWithMove mempty
311−makeWrapped ''NodeInfo
324+ mappend = (<>)