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153 lines
9.5 KiB
Haskell
153 lines
9.5 KiB
Haskell
{-# LANGUAGE RankNTypes, ScopedTypeVariables #-}
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module Alignment
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( hasChanges
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, numberedRows
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, alignDiff
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, alignBranch
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, applyThese
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, modifyJoin
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) where
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import Prologue hiding (fst, snd)
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import Data.Align
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import Data.Bifunctor.Join
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import Data.Functor.Both
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import Data.List (partition)
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import Data.Maybe (fromJust)
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import Data.Record
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import Data.These
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import Diff
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import Info
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import Patch
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import Range
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import Source hiding (break, fromList, uncons)
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import SplitDiff
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import Syntax
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import Term
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-- | Assign line numbers to the lines on each side of a list of rows.
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numberedRows :: [Join These a] -> [Join These (Int, a)]
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numberedRows = countUp (both 1 1)
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where countUp _ [] = []
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countUp from (row : rows) = numberedLine from row : countUp (nextLineNumbers from row) rows
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numberedLine from row = fromJust ((,) <$> modifyJoin (uncurry These) from `applyThese` row)
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nextLineNumbers from row = modifyJoin (fromThese identity identity) (succ <$ row) <*> from
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-- | Determine whether a line contains any patches.
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hasChanges :: (Foldable f, Functor f) => SplitDiff f annotation -> Bool
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hasChanges = or . (True <$)
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-- | Align a Diff into a list of Join These SplitDiffs representing the (possibly blank) lines on either side.
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alignDiff :: HasField fields Range => Both (Source Char) -> SyntaxDiff leaf fields -> [Join These (SplitSyntaxDiff leaf fields)]
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alignDiff sources diff = iter (alignSyntax (runBothWith ((Join .) . These)) wrap getRange sources) (alignPatch sources <$> diff)
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-- | Align the contents of a patch into a list of lines on the corresponding side(s) of the diff.
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alignPatch :: forall fields leaf. HasField fields Range => Both (Source Char) -> Patch (SyntaxTerm leaf fields) -> [Join These (SplitSyntaxDiff leaf fields)]
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alignPatch sources patch = case patch of
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Delete term -> fmap (pure . SplitDelete) <$> alignSyntax' this (fst sources) term
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Insert term -> fmap (pure . SplitInsert) <$> alignSyntax' that (snd sources) term
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Replace term1 term2 -> fmap (pure . SplitReplace) <$> alignWith (fmap (these identity identity const . runJoin) . Join)
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(alignSyntax' this (fst sources) term1)
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(alignSyntax' that (snd sources) term2)
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where getRange = characterRange . extract
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alignSyntax' :: (forall a. Identity a -> Join These a) -> Source Char -> SyntaxTerm leaf fields -> [Join These (SyntaxTerm leaf fields)]
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alignSyntax' side source term = hylo (alignSyntax side cofree getRange (Identity source)) runCofree (Identity <$> term)
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this = Join . This . runIdentity
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that = Join . That . runIdentity
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-- | The Applicative instance f is either Identity or Both. Identity is for Terms in Patches, Both is for Diffs in unchanged portions of the diff.
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alignSyntax :: (Applicative f, HasField fields Range) => (forall a. f a -> Join These a) -> (SyntaxTermF leaf fields term -> term) -> (term -> Range) -> f (Source Char) -> TermF (Syntax leaf) (f (Record fields)) [Join These term] -> [Join These term]
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alignSyntax toJoinThese toNode getRange sources (infos :< syntax) = catMaybes $ case syntax of
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Leaf s -> wrapInBranch (const (Leaf s)) <$> alignBranch getRange [] bothRanges
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Syntax.Comment a -> wrapInBranch (const (Syntax.Comment a)) <$> alignBranch getRange [] bothRanges
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Fixed children -> wrapInBranch Fixed <$> alignBranch getRange (join children) bothRanges
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_ -> wrapInBranch Indexed <$> alignBranch getRange (join (toList syntax)) bothRanges
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where bothRanges = modifyJoin (fromThese [] []) lineRanges
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lineRanges = toJoinThese $ actualLineRanges <$> (characterRange <$> infos) <*> sources
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wrapInBranch constructor = applyThese $ toJoinThese ((\ info (range, children) -> toNode (setCharacterRange info range :< constructor children)) <$> infos)
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-- | Given a function to get the range, a list of already-aligned children, and the lists of ranges spanned by a branch, return the aligned lines.
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alignBranch :: (term -> Range) -> [Join These term] -> Both [Range] -> [Join These (Range, [term])]
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-- There are no more ranges, so we’re done.
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alignBranch _ _ (Join ([], [])) = []
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-- There are no more children, so we can just zip the remaining ranges together.
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alignBranch _ [] ranges = runBothWith (alignWith Join) (fmap (flip (,) []) <$> ranges)
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-- There are both children and ranges, so we need to proceed line by line
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alignBranch getRange children ranges = case intersectingChildren of
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-- No child intersects the current ranges on either side, so advance.
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[] -> (flip (,) [] <$> headRanges) : alignBranch getRange children (drop 1 <$> ranges)
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-- At least one child intersects on at least one side.
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_ -> case intersectionsWithHeadRanges <$> listToMaybe symmetricalChildren of
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-- At least one child intersects on both sides, so align symmetrically.
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Just (True, True) -> let (line, remaining) = lineAndRemaining intersectingChildren (Just headRanges) in
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line $ alignBranch getRange (remaining <> nonIntersectingChildren) (drop 1 <$> ranges)
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-- A symmetrical child intersects on the right, so align asymmetrically on the left.
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Just (False, True) -> alignAsymmetrically leftRange first
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-- A symmetrical child intersects on the left, so align asymmetrically on the right.
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Just (True, False) -> alignAsymmetrically rightRange second
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-- No symmetrical child intersects, so align asymmetrically, picking the left side first to match the deletion/insertion order convention in diffs.
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_ -> if any (isThis . runJoin) asymmetricalChildren
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then alignAsymmetrically leftRange first
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else alignAsymmetrically rightRange second
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where (intersectingChildren, nonIntersectingChildren) = partition (or . intersects getRange headRanges) children
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(symmetricalChildren, asymmetricalChildren) = partition (isThese . runJoin) intersectingChildren
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intersectionsWithHeadRanges = fromThese True True . runJoin . intersects getRange headRanges
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Just headRanges = Join <$> bisequenceL (runJoin (listToMaybe <$> Join (runBothWith These ranges)))
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(leftRange, rightRange) = splitThese headRanges
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alignAsymmetrically range advanceBy = let (line, remaining) = lineAndRemaining asymmetricalChildren range in
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line $ alignBranch getRange (remaining <> symmetricalChildren <> nonIntersectingChildren) (modifyJoin (advanceBy (drop 1)) ranges)
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lineAndRemaining _ Nothing = (identity, [])
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lineAndRemaining children (Just ranges) = let (intersections, remaining) = alignChildren getRange children ranges in
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((:) $ (,) <$> ranges `applyToBoth` (sortBy (compare `on` getRange) <$> intersections), remaining)
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-- | Given a list of aligned children, produce lists of their intersecting first lines, and a list of the remaining lines/nonintersecting first lines.
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alignChildren :: (term -> Range) -> [Join These term] -> Join These Range -> (Both [term], [Join These term])
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alignChildren _ [] _ = (both [] [], [])
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alignChildren getRange (first:rest) headRanges
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| ~(l, r) <- splitThese first
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= case intersectionsWithHeadRanges first of
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-- It intersects on both sides, so we can just take the first line whole.
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(True, True) -> ((<>) <$> toTerms first <*> firstRemaining, restRemaining)
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-- It only intersects on the left, so split it up.
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(True, False) -> ((<>) <$> toTerms (fromJust l) <*> firstRemaining, maybe identity (:) r restRemaining)
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-- It only intersects on the right, so split it up.
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(False, True) -> ((<>) <$> toTerms (fromJust r) <*> firstRemaining, maybe identity (:) l restRemaining)
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-- It doesn’t intersect at all, so skip it and move along.
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(False, False) -> (firstRemaining, first:restRemaining)
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| otherwise = alignChildren getRange rest headRanges
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where (firstRemaining, restRemaining) = alignChildren getRange rest headRanges
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toTerms line = modifyJoin (fromThese [] []) (pure <$> line)
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intersectionsWithHeadRanges = fromThese False False . runJoin . intersects getRange headRanges
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-- | Test ranges and terms for intersection on either or both sides.
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intersects :: (term -> Range) -> Join These Range -> Join These term -> Join These Bool
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intersects getRange ranges line = intersectsRange <$> ranges `applyToBoth` modifyJoin (fromThese (Range (-1) (-1)) (Range (-1) (-1))) (getRange <$> line)
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-- | Split a These value up into independent These values representing the left and right sides, if any.
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splitThese :: Join These a -> (Maybe (Join These a), Maybe (Join These a))
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splitThese these = fromThese Nothing Nothing $ bimap (Just . Join . This) (Just . Join . That) (runJoin these)
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infixl 4 `applyThese`
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-- | Like `<*>`, but it returns its result in `Maybe` since the result is the intersection of the shapes of the inputs.
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applyThese :: Join These (a -> b) -> Join These a -> Maybe (Join These b)
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applyThese (Join fg) (Join ab) = fmap Join . uncurry maybeThese $ uncurry (***) (bimap (<*>) (<*>) (unpack fg)) (unpack ab)
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where unpack = fromThese Nothing Nothing . bimap Just Just
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infixl 4 `applyToBoth`
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-- | Like `<*>`, but it takes a `Both` on the right to ensure that it can always return a value.
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applyToBoth :: Join These (a -> b) -> Both a -> Join These b
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applyToBoth (Join fg) (Join (a, b)) = Join $ these (This . ($ a)) (That . ($ b)) (\ f g -> These (f a) (g b)) fg
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-- Map over the bifunctor inside a Join, producing another Join.
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modifyJoin :: (p a a -> q b b) -> Join p a -> Join q b
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modifyJoin f = Join . f . runJoin
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-- | Given a pair of Maybes, produce a These containing Just their values, or Nothing if they haven’t any.
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maybeThese :: Maybe a -> Maybe b -> Maybe (These a b)
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maybeThese (Just a) (Just b) = Just (These a b)
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maybeThese (Just a) _ = Just (This a)
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maybeThese _ (Just b) = Just (That b)
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maybeThese _ _ = Nothing
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