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📝 mergeMaybe, beforeTerm, and afterTerm.

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This commit is contained in:
Rob Rix 2016-07-05 09:45:28 -04:00
parent 5ea93ba8de
commit baafd5f7a8
1 changed files with 3 additions and 0 deletions
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src/Diff.hs
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@ -25,6 +25,7 @@ diffSum patchCost diff = sum $ fmap patchCost diff
diffCost :: Diff a annotation -> Integer
diffCost = diffSum $ patchSum termSize
-- | Merge a diff using a function to provide the Term (in Maybe, to simplify recovery of the before/after state) for every Patch.
mergeMaybe :: (Patch (Term leaf annotation) -> Maybe (Term leaf annotation)) -> Diff leaf annotation -> Maybe (Term leaf annotation)
mergeMaybe transform = cata algebra . fmap transform
where algebra :: FreeF (CofreeF (Syntax leaf) (Both annotation)) (Maybe (Term leaf annotation)) (Maybe (Term leaf annotation)) -> Maybe (Term leaf annotation)
@ -35,8 +36,10 @@ mergeMaybe transform = cata algebra . fmap transform
Fixed i -> Fixed (catMaybes i)
Keyed i -> Keyed (Map.fromList (Map.toList i >>= (\ (k, v) -> maybe [] (pure . (,) k) v)))
-- | Recover the before state of a diff.
beforeTerm :: Diff leaf annotation -> Maybe (Term leaf annotation)
beforeTerm = mergeMaybe before
-- | Recover the after state of a diff.
afterTerm :: Diff leaf annotation -> Maybe (Term leaf annotation)
afterTerm = mergeMaybe after