Diff entirely within Both.

src/Alignment.hs

@@ -49,46 +49,47 @@ hasChanges = or . fmap (or . (True <$))
 
 -- | Split a diff, which may span multiple lines, into rows of split diffs paired with the Range of characters spanned by that Row on each side of the diff.
 splitDiffByLines :: Both (Source Char) -> Diff leaf Info -> [Row (SplitDiff leaf Info, Range)]
-splitDiffByLines sources = fmap (bothWithDefault (Line [])) . toList . iter (\ (Annotated infos syntax) -> splitAbstractedTerm ((Free .) . Annotated) (justBoth sources) (justBoth infos) syntax) . fmap (splitPatchByLines sources)
+splitDiffByLines sources = toList . iter (\ (Annotated infos syntax) -> splitAbstractedTerm ((Free .) . Annotated) sources infos syntax) . fmap (splitPatchByLines sources)
 
 -- | Split a patch, which may span multiple lines, into rows of split diffs.
-splitPatchByLines :: Both (Source Char) -> Patch (Term leaf Info) -> Adjoined (BothMaybe (Line (SplitDiff leaf Info, Range)))
+splitPatchByLines :: Both (Source Char) -> Patch (Term leaf Info) -> Adjoined (Both (Line (SplitDiff leaf Info, Range)))
 splitPatchByLines sources patch = wrapTermInPatch <$> lines
-    where lines = sequenceL $ justBoth (splitAndFoldTerm <$> sources <*> maybeBothOfThese (unPatch patch))
-          splitAndFoldTerm source (Just term) = (runIdentity <$> cata (splitAbstractedTerm (:<) (Identity source)) (Identity <$> term))
-          splitAndFoldTerm _ _ = nil
+    where lines = splitAndFoldTerm (unPatch patch)
+          splitAndFoldTerm (This deleted) = modifyBoth (second (const $ Line [])) <$> cata (splitAbstractedTerm (:<) sources) (pure <$> deleted)
+          splitAndFoldTerm (That inserted) = modifyBoth (first (const $ Line [])) <$> cata (splitAbstractedTerm (:<) sources) (pure <$> inserted)
+          splitAndFoldTerm (These deleted inserted) = alignRows $ both (fst <$> splitAndFoldTerm (This deleted)) (snd <$> splitAndFoldTerm (That inserted))
           wrapTermInPatch = fmap (fmap (first (Pure . constructor patch)))
           constructor (Replace _ _) = SplitReplace
           constructor (Insert _) = SplitInsert
           constructor (Delete _) = SplitDelete
 
 -- | Split a term comprised of an Info & Syntax up into one `outTerm` (abstracted by an alignment function & constructor) per line in `Source`.
-splitAbstractedTerm :: (Applicative f, Coalescent (f (Line (Maybe (Identity outTerm), Range))), Coalescent (f (Line (Maybe (T.Text, outTerm), Range))), Crosswalk f, Foldable f) => (Info -> Syntax leaf outTerm -> outTerm) -> f (Source Char) -> f Info -> Syntax leaf (Adjoined (f (Line (outTerm, Range)))) -> Adjoined (f (Line (outTerm, Range)))
+splitAbstractedTerm :: (Info -> Syntax leaf outTerm -> outTerm) -> Both (Source Char) -> Both Info -> Syntax leaf (Adjoined (Both (Line (outTerm, Range)))) -> Adjoined (Both (Line (outTerm, Range)))
 splitAbstractedTerm makeTerm sources infos syntax = case syntax of
-  Leaf a -> sequenceL $ fmap <$> ((\ categories -> fmap (\ range -> (makeTerm (Info range categories) (Leaf a), range))) <$> (Diff.categories <$> infos)) <*> (fmap fromList $ linesInRangeOfSource <$> (characterRange <$> infos) <*> sources)
+  Leaf a -> alignRows $ fmap <$> ((\ categories -> fmap (\ range -> (makeTerm (Info range categories) (Leaf a), range))) <$> (Diff.categories <$> infos)) <*> (fmap fromList $ linesInRangeOfSource <$> (characterRange <$> infos) <*> sources)
   Indexed children -> adjoinChildren sources infos (constructor (Indexed . fmap runIdentity)) (Identity <$> children)
   Fixed children -> adjoinChildren sources infos (constructor (Fixed . fmap runIdentity)) (Identity <$> children)
   Keyed children -> adjoinChildren sources infos (constructor (Keyed . Map.fromList)) (Map.toList children)
   where constructor with info = makeTerm info . with
 
 -- | Adjoin a branch term’s lines, wrapping children & context in branch nodes using a constructor.
-adjoinChildren :: (Copointed c, Functor c, Applicative f, Coalescent (f (Line (Maybe (c a), Range))), Crosswalk f, Foldable f) => f (Source Char) -> f Info -> (Info -> [c a] -> outTerm) -> [c (Adjoined (f (Line (a, Range))))] -> Adjoined (f (Line (outTerm, Range)))
+adjoinChildren :: (Copointed c, Functor c) => Both (Source Char) -> Both Info -> (Info -> [c a] -> outTerm) -> [c (Adjoined (Both (Line (a, Range))))] -> Adjoined (Both (Line (outTerm, Range)))
 adjoinChildren sources infos constructor children = wrap <$> leadingContext <> lines
   where (lines, next) = foldr (childLines sources) (mempty, end <$> ranges) children
         ranges = characterRange <$> infos
         categories = Diff.categories <$> infos
-        leadingContext = sequenceL $ fromList . fmap (fmap ((,) Nothing)) <$> (linesInRangeOfSource <$> (Range <$> (start <$> ranges) <*> next) <*> sources)
+        leadingContext = alignRows $ fromList . fmap (fmap ((,) Nothing)) <$> (linesInRangeOfSource <$> (Range <$> (start <$> ranges) <*> next) <*> sources)
         wrap = (wrapLineContents <$> (makeBranchTerm constructor <$> categories <*> next) <*>)
         makeBranchTerm constructor categories next children = let range = unionRangesFrom (rangeAt next) $ Prelude.snd <$> children in
           (constructor (Info range categories) . catMaybes . toList $ Prelude.fst <$> children, range)
 
 -- | Accumulate the lines of and between a branch term’s children.
-childLines :: (Copointed c, Functor c, Applicative f, Coalescent (f (Line (Maybe (c a), Range))), Crosswalk f, Foldable f) => f (Source Char) -> c (Adjoined (f (Line (a, Range)))) -> (Adjoined (f (Line (Maybe (c a), Range))), f Int) -> (Adjoined (f (Line (Maybe (c a), Range))), f Int)
+childLines :: (Copointed c, Functor c) => Both (Source Char) -> c (Adjoined (Both (Line (a, Range)))) -> (Adjoined (Both (Line (Maybe (c a), Range))), Both Int) -> (Adjoined (Both (Line (Maybe (c a), Range))), Both Int)
 -- We depend on source ranges increasing monotonically. If a child invalidates that, e.g. if it’s a move in a Keyed node, we don’t output rows for it in this iteration. (It will still show up in the diff as context rows.) This works around https://github.com/github/semantic-diff/issues/488.
 childLines sources child (followingLines, next) | or $ (>) . end <$> childRanges <*> next = (followingLines, next)
                                                 | otherwise =
   ((placeChildAndRangeInContainer <$> copoint child)
-  <> sequenceL (fromList . pairWithNothing <$> trailingContextLines)
+  <> alignRows (fromList . pairWithNothing <$> trailingContextLines)
   <> followingLines, start <$> childRanges)
   where pairWithNothing = fmap (fmap ((,) Nothing))
         placeChildAndRangeInContainer = fmap (fmap (first (Just . (<$ child))))