-- Copyright (C) 2002-2003 David Roundy -- -- This program is free software; you can redistribute it and/or modify -- it under the terms of the GNU General Public License as published by -- the Free Software Foundation; either version 2, or (at your option) -- any later version. -- -- This program is distributed in the hope that it will be useful, -- but WITHOUT ANY WARRANTY; without even the implied warranty of -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -- GNU General Public License for more details. -- -- You should have received a copy of the GNU General Public License -- along with this program; see the file COPYING. If not, write to -- the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, -- Boston, MA 02110-1301, USA. {-# OPTIONS_GHC -fno-warn-orphans -fno-warn-incomplete-patterns #-} {-# LANGUAGE CPP #-} module Darcs.Patch.V1.Commute ( merge, merger, unravel, publicUnravel, ) where import Control.Monad ( MonadPlus, mplus, msum, mzero, guard ) import Control.Applicative ( Applicative(..), Alternative(..) ) import Data.Maybe ( isJust ) import Darcs.Patch.Commute ( toFwdCommute, selfCommuter ) import Darcs.Patch.CommuteFn ( commuterIdFL, commuterFLId ) import Darcs.Patch.ConflictMarking ( mangleUnravelled ) import Darcs.Util.Path ( FileName ) import Darcs.Patch.Invert ( invertRL ) import Darcs.Patch.Merge ( Merge(..) ) import Darcs.Patch.Patchy ( Commute(..), PatchInspect(..), Invert(..) ) import Darcs.Patch.V1.Core ( Patch(..), isMerger, mergerUndo ) import Darcs.Patch.Conflict ( Conflict(..), CommuteNoConflicts(..) ) import Darcs.Patch.Effect ( Effect(..) ) import Darcs.Patch.FileHunk ( IsHunk(..) ) import Darcs.Patch.Prim ( FromPrim(..), PrimPatch, is_filepatch, sortCoalesceFL, ) import Darcs.Patch.Permutations ( headPermutationsRL, simpleHeadPermutationsFL ) import Darcs.Util.Printer ( text, vcat, ($$) ) import Darcs.Patch.V1.Show ( showPatch_ ) import Data.List ( nub, nubBy ) import Data.List.Ordered ( nubSort ) #include "impossible.h" import Darcs.Patch.Witnesses.Sealed ( Sealed(..) , mapSeal, unseal, FlippedSeal(..), mapFlipped , unsafeUnseal, unsafeUnsealFlipped ) import Darcs.Patch.Witnesses.Eq ( EqCheck(..), MyEq(..) ) import Darcs.Patch.Witnesses.Unsafe ( unsafeCoerceP, unsafeCoercePStart , unsafeCoercePEnd ) import Darcs.Patch.Witnesses.Ordered ( mapFL_FL, FL(..), RL(..), (:/\:)(..), (:<)(..), (:\/:)(..), (:>)(..), lengthFL, mapRL, reverseFL, reverseRL, concatFL ) data Perhaps a = Unknown | Failed | Succeeded a instance Functor Perhaps where fmap _ Unknown = Unknown fmap _ Failed = Failed fmap f (Succeeded x) = Succeeded (f x) instance Applicative Perhaps where pure = Succeeded _ <*> Failed = Failed _ <*> Unknown = Unknown Failed <*> _ = Failed Unknown <*> _ = Unknown Succeeded f <*> Succeeded x = Succeeded (f x) instance Monad Perhaps where (Succeeded x) >>= k = k x Failed >>= _ = Failed Unknown >>= _ = Unknown return = Succeeded fail _ = Unknown instance Alternative Perhaps where empty = Unknown Unknown <|> ys = ys Failed <|> _ = Failed (Succeeded x) <|> _ = Succeeded x instance MonadPlus Perhaps where mzero = Unknown mplus = (<|>) toMaybe :: Perhaps a -> Maybe a toMaybe (Succeeded x) = Just x toMaybe _ = Nothing toPerhaps :: Maybe a -> Perhaps a toPerhaps (Just x) = Succeeded x toPerhaps Nothing = Failed -- | 'cleverCommute' attempts to commute two patches @p1@ and @p2@, in their -- original order, with the given commute function. If the commute function -- doesn't know how to handle the patches (i.e. it returns Unknown as a -- result), then we try again with @invert p2@ and @invert p1@ (inverting the -- results, if succesful). -- -- TODO: when can the first attempt fail, but the second not? What's so clever -- in this function? cleverCommute :: Invert prim => CommuteFunction prim -> CommuteFunction prim cleverCommute c (p1: Succeeded x Failed -> Failed Unknown -> case c (invert p2 :< invert p1) of Succeeded (p1' :< p2') -> Succeeded (invert p2' :< invert p1') Failed -> Failed Unknown -> Unknown -- | If we have two Filepatches which modify different files, we can return a -- result early, since the patches trivially commute. speedyCommute :: PrimPatch prim => CommuteFunction prim speedyCommute (p1 :< p2) | isJust p1_modifies && isJust p2_modifies && p1_modifies /= p2_modifies = Succeeded (unsafeCoerceP p2 :< unsafeCoerceP p1) | otherwise = Unknown where p1_modifies = isFilepatchMerger p1 p2_modifies = isFilepatchMerger p2 everythingElseCommute :: forall prim . PrimPatch prim => CommuteFunction prim everythingElseCommute (PP px :< PP py) = toPerhaps $ do x' :> y' <- commute (py :> px) return (PP y' :< PP x') everythingElseCommute _xx = msum [ cleverCommute commuteRecursiveMerger _xx ,cleverCommute otherCommuteRecursiveMerger _xx ] {- Note that it must be true that commutex (A^-1 A, P) = Just (P, A'^-1 A') and if commutex (A, B) == Just (B', A') then commutex (B^-1, A^-1) == Just (A'^-1, B'^-1) -} unsafeMerger :: PrimPatch prim => String -> Patch prim wX wY -> Patch prim wX wZ -> Patch prim wA wB unsafeMerger x p1 p2 = unsafeCoercePStart $ unsafeUnseal $ merger x p1 p2 -- | Attempt to commute two patches, the first of which is a Merger patch. mergerCommute :: PrimPatch prim => (Patch prim :< Patch prim) wX wY -> Perhaps ((Patch prim :< Patch prim) wX wY) mergerCommute (Merger _ _ p1 p2 :< pA) | unsafeCompare pA p1 = Succeeded (unsafeMerger "0.0" p2 p1 :< unsafeCoercePStart p2) | unsafeCompare pA (invert (unsafeMerger "0.0" p2 p1)) = Failed mergerCommute (Merger _ _ (Merger _ _ c b) (Merger _ _ c' a) :< Merger _ _ b' c'') | unsafeCompare b' b && unsafeCompare c c' && unsafeCompare c c'' = Succeeded (unsafeMerger "0.0" (unsafeMerger "0.0" b (unsafeCoercePStart a)) (unsafeMerger "0.0" b c) :< unsafeMerger "0.0" b (unsafeCoercePStart a)) mergerCommute _ = Unknown instance PrimPatch prim => Merge (Patch prim) where merge (y :\/: z) = case actualMerge (y:\/:z) of -- actualMerge returns one "arm" of a merge result (@y'@, which applies -- "after" @z@), but we need to return both arms. We therefore commute -- @z@ and @y'@, to obtain a @z'@, which applies "after" @y'' == y@. Sealed y' -> case commute (z :> y') of Nothing -> bugDoc $ text "merge_patches bug" $$ showPatch_ y $$ showPatch_ z $$ showPatch_ y' Just (_ :> z') -> unsafeCoercePStart z' :/\: y' instance PrimPatch prim => Commute (Patch prim) where commute x = toMaybe $ msum [toFwdCommute speedyCommute x, toFwdCommute (cleverCommute mergerCommute) x, toFwdCommute everythingElseCommute x ] instance PrimPatch prim => PatchInspect (Patch prim) where -- Recurse on everything, these are potentially spoofed patches listTouchedFiles (Merger _ _ p1 p2) = nubSort $ listTouchedFiles p1 ++ listTouchedFiles p2 listTouchedFiles c@(Regrem{}) = listTouchedFiles $ invert c listTouchedFiles (PP p) = listTouchedFiles p hunkMatches f (Merger _ _ p1 p2) = hunkMatches f p1 || hunkMatches f p2 hunkMatches f c@(Regrem{}) = hunkMatches f $ invert c hunkMatches f (PP p) = hunkMatches f p commuteNoMerger :: PrimPatch prim => MaybeCommute prim commuteNoMerger x = toMaybe $ msum [speedyCommute x, everythingElseCommute x] isFilepatchMerger :: PrimPatch prim => Patch prim wX wY -> Maybe FileName isFilepatchMerger (PP p) = is_filepatch p isFilepatchMerger (Merger _ _ p1 p2) = do f1 <- isFilepatchMerger p1 f2 <- isFilepatchMerger p2 if f1 == f2 then return f1 else Nothing isFilepatchMerger (Regrem und unw p1 p2) = isFilepatchMerger (Merger und unw p1 p2) commuteRecursiveMerger :: PrimPatch prim => (Patch prim :< Patch prim) wX wY -> Perhaps ((Patch prim :< Patch prim) wX wY) commuteRecursiveMerger (p@(Merger _ _ p1 p2) :< pA) = toPerhaps $ do (_ :> pA') <- commuterIdFL selfCommuter (pA :> undo) _ <- commuterIdFL selfCommuter (pA' :> invert undo) (_ :> pAmid) <- commute (pA :> unsafeCoercePStart (invert p1)) (p1' :> pAx) <- commute (pAmid :> p1) guard (pAx `unsafeCompare` pA) (p2' :> _) <- commute (pAmid :> p2) (p2o :> _) <- commute (invert pAmid :> p2') guard (p2o `unsafeCompare` p2) let p' = if unsafeCompare p1' p1 && unsafeCompare p2' p2 then unsafeCoerceP p else unsafeMerger "0.0" p1' p2' undo' = mergerUndo p' (pAo :> _) <- commuterFLId selfCommuter (undo' :> pA') guard (pAo `unsafeCompare` pA) return (pA' :< p') where undo = mergerUndo p commuteRecursiveMerger _ = Unknown otherCommuteRecursiveMerger :: PrimPatch prim => (Patch prim :< Patch prim) wX wY -> Perhaps ((Patch prim :< Patch prim) wX wY) otherCommuteRecursiveMerger (pA':< p_old@(Merger _ _ p1' p2')) = toPerhaps $ do (pA :> _) <- commuterFLId selfCommuter (mergerUndo p_old :> pA') (pAmid :> p1) <- commute (unsafeCoercePEnd p1' :> pA) (_ :> pAmido) <- commute (pA :> invert p1) guard (pAmido `unsafeCompare` pAmid) (p2 :> _) <- commute (invert pAmid :> p2') (p2o' :> _) <- commute (pAmid :> p2) guard (p2o' `unsafeCompare` p2') let p = if p1 `unsafeCompare` p1' && p2 `unsafeCompare` p2' then unsafeCoerceP p_old else unsafeMerger "0.0" p1 p2 undo = mergerUndo p guard (not $ pA `unsafeCompare` p1) -- special case here... (_ :> pAo') <- commuterIdFL selfCommuter (pA :> undo) guard (pAo' `unsafeCompare` pA') return (p :< pA) otherCommuteRecursiveMerger _ = Unknown type CommuteFunction prim = forall wX wY . (Patch prim :< Patch prim) wX wY -> Perhaps ((Patch prim :< Patch prim) wX wY) type MaybeCommute prim = forall wX wY . (Patch prim :< Patch prim) wX wY -> Maybe ((Patch prim :< Patch prim) wX wY) revCommuteFLId :: MaybeCommute prim -> (FL (Patch prim) :< Patch prim) wX wY -> Maybe ((Patch prim :< FL (Patch prim)) wX wY) revCommuteFLId _ (NilFL :< p) = return (p :< NilFL) revCommuteFLId commuter ((q :>: qs) :< p) = do p' :< q' <- commuter (q :< p) p'' :< qs' <- revCommuteFLId commuter (qs :< p') return (p'' :< (q' :>: qs')) -- | elegantMerge attempts to perform the "intuitive" merge of two patches, -- from a common starting context @wX@. elegantMerge :: PrimPatch prim => (Patch prim :\/: Patch prim) wX wY -> Maybe ((Patch prim :/\: Patch prim) wX wY) elegantMerge (p1 :\/: p2) = do p1' :> ip2' <- commute (invert p2 :> p1) p1o :> _ <- commute (p2 :> p1') guard $ unsafeCompare p1o p1 -- should be a redundant check return $ invert ip2' :/\: p1' {- A note about mergers and type witnesses --------------------------------------- The merger code predates the introduction of type witnesses, and because of its complexity has proved the hardest part of the codebase to retrofit. Attempting to do this has exposed various places where the code behaves oddly (e.g. 'putBefore' below); these are likely to be bugs but fixing them would be potentially disruptive and dangerous as it might change the existing merge behaviour and thus break existing repositories. As a result the addition of witnesses to this code has required the liberal use of unsafe operators. In effect, witnesses bring no safety in this area; the sole purpose of adding them here was to allow this code to run as part of a codebase that uses witnesses everywhere else. A key problem point is the type of the 'Merger' and 'Regrem' constructors of Patch, where the witnesses seem odd. It is likely that some or many of the unsafe operations could be removed by finding a better type for these constructors. -} -- |actualMerge attempts to perform a merge; if successful, it returns the -- "right" branch of the merge -- -- TODO: why does this code throw away the other branch, only for merge to -- rebuild it? actualMerge :: PrimPatch prim => (Patch prim :\/: Patch prim) wX wY -> Sealed (Patch prim wY) actualMerge (p1 :\/: p2) = case elegantMerge (p1:\/:p2) of Just (_ :/\: p1') -> Sealed p1' Nothing -> merger "0.0" p2 p1 -- Recreates a patch history in reverse. unwind :: Patch prim wX wY -> Sealed (RL (Patch prim) wX) unwind (Merger _ unwindings _ _) = Sealed unwindings unwind p = Sealed (p :<: NilRL) -- Recreates a patch history in reverse. The patch being unwound is always at -- the start of the list of patches. trueUnwind :: PrimPatch prim => Patch prim wX wY -> Sealed (RL (Patch prim) wX) trueUnwind p@(Merger _ _ p1 p2) = case (unwind p1, unwind p2) of (Sealed (_:<:p1s),Sealed (_:<:p2s)) -> Sealed (p :<: unsafeCoerceP p1 :<: unsafeUnsealFlipped (reconcileUnwindings p p1s (unsafeCoercePEnd p2s))) _ -> impossible trueUnwind _ = impossible reconcileUnwindings :: PrimPatch prim => Patch prim wA wB -> RL (Patch prim) wX wZ -> RL (Patch prim) wY wZ -> FlippedSeal (RL (Patch prim)) wZ reconcileUnwindings _ NilRL p2s = FlippedSeal p2s reconcileUnwindings _ p1s NilRL = FlippedSeal p1s reconcileUnwindings p (p1:<:p1s) p2s@(p2:<:tp2s) = case [(p1s', p2s')| p1s'@(hp1s':<:_) <- headPermutationsRL (p1:<:p1s), p2s'@(hp2s':<:_) <- headPermutationsRL p2s, hp1s' `unsafeCompare` hp2s'] of ((p1':<:p1s', _:<:p2s'):_) -> mapFlipped (p1' :<:) $ reconcileUnwindings p p1s' (unsafeCoercePEnd p2s') [] -> case reverseFL `fmap` putBefore p1 (reverseRL p2s) of Just p2s' -> mapFlipped (p1 :<:) $ reconcileUnwindings p p1s p2s' Nothing -> case fmap reverseFL $ putBefore p2 $ reverseRL (p1:<:p1s) of Just p1s' -> mapFlipped (p2 :<:) $ reconcileUnwindings p p1s' tp2s Nothing -> bugDoc $ text "in function reconcileUnwindings" $$ text "Original patch:" $$ showPatch_ p _ -> bug "in reconcileUnwindings" -- This code seems wrong, shouldn't the commute be invert p1 :> p2 ? And why isn't p1' re-inverted? -- it seems to have been this way forever: -- Fri May 23 10:27:04 BST 2003 droundy@abridgegame.org -- * fix bug in unwind and add docs on unwind algorithm. putBefore :: PrimPatch prim => Patch prim wY wZ -> FL (Patch prim) wX wZ -> Maybe (FL (Patch prim) wY wW) putBefore p1 (p2:>:p2s) = do p1' :> p2' <- commute (unsafeCoerceP p2 :> invert p1) _ <- commute (p2' :> p1) (unsafeCoerceP p2' :>:) `fmap` putBefore p1' (unsafeCoerceP p2s) putBefore _ NilFL = Just (unsafeCoerceP NilFL) instance PrimPatch prim => CommuteNoConflicts (Patch prim) where commuteNoConflicts (x:>y) = do x' :< y' <- commuteNoMerger (y :< x) return (y':>x') instance PrimPatch prim => Conflict (Patch prim) where resolveConflicts patch = rcs NilFL (patch :<: NilRL) where rcs :: FL (Patch prim) wY wW -> RL (Patch prim) wX wY -> [[Sealed (FL prim wW)]] rcs _ NilRL = [] rcs passedby (p@(Merger{}):<:ps) = case revCommuteFLId commuteNoMerger (passedby: map Sealed (nubBy unsafeCompare $ effect (unsafeCoercePStart $ unsafeUnseal (glump09 p1 p2)) : map (unsafeCoercePStart . unsafeUnseal) (unravel p')) : rcs (p :>: passedby) ps Nothing -> rcs (p :>: passedby) ps _ -> impossible rcs passedby (p:<:ps) = seq passedby $ rcs (p :>: passedby) ps -- This type seems wrong - the most natural type for the result would seem to be -- [Sealed (FL Prim wX)], given the type of unwind. -- However downstream code in darcs convert assumes the wY type, and I was unable -- to figure out whether this could/should reasonably be changed -- Ganesh 13/4/10 publicUnravel :: PrimPatch prim => Patch prim wX wY -> [Sealed (FL prim wY)] publicUnravel = map (mapSeal unsafeCoercePStart) . unravel unravel :: PrimPatch prim => Patch prim wX wY -> [Sealed (FL prim wX)] unravel p = nub $ map (mapSeal (sortCoalesceFL . concatFL . mapFL_FL effect)) $ getSupers $ map (mapSeal reverseRL) $ unseal (newUr p) $ unwind p getSupers :: PrimPatch prim => [Sealed (FL (Patch prim) wX)] -> [Sealed (FL (Patch prim) wX)] getSupers (x:xs) = case filter (not.(x `isSuperpatchOf`)) xs of xs' -> if any (`isSuperpatchOf` x) xs' then getSupers xs' else x : getSupers xs' getSupers [] = [] isSuperpatchOf :: PrimPatch prim => Sealed (FL (Patch prim) wX) -> Sealed (FL (Patch prim) wX) -> Bool Sealed x `isSuperpatchOf` Sealed y | lengthFL y > lengthFL x = False -- should be just an optimisation Sealed x `isSuperpatchOf` Sealed y = x `iso` y where iso :: PrimPatch prim => FL (Patch prim) wX wY -> FL (Patch prim) wX wZ -> Bool _ `iso` NilFL = True NilFL `iso` _ = False a `iso` (b:>:bs) = head $ ([as `iso` bs | (ah :>: as) <- simpleHeadPermutationsFL a, IsEq <- [ah =\/= b]] :: [Bool]) ++ [False] -- | merger takes two patches, (which have been determined to conflict) and -- constructs a Merger patch to represent the conflict. @p1@ is considered to -- be conflicting with @p2@ (@p1@ is the "first" patch in the repo ordering), -- the resulting Merger is therefore a representation of @p2@. merger :: PrimPatch prim => String -> Patch prim wX wY -> Patch prim wX wZ -> Sealed (Patch prim wY) merger "0.0" p1 p2 = Sealed $ Merger undoit unwindings p1 p2 where fake_p = Merger NilFL NilRL p1 p2 unwindings = unsafeUnseal (trueUnwind fake_p) p = Merger NilFL unwindings p1 p2 undoit = case (isMerger p1, isMerger p2) of (True ,True ) -> case unwind p of Sealed (_:<:t) -> unsafeCoerceP $ invertRL t _ -> impossible (False,False) -> unsafeCoerceP $ invert p1 :>: NilFL (True ,False) -> unsafeCoerceP NilFL (False,True ) -> unsafeCoerceP $ invert p1 :>: mergerUndo p2 merger g _ _ = error $ "Cannot handle mergers other than version 0.0\n"++g ++ "\nPlease use darcs optimize --modernize with an older darcs." glump09 :: PrimPatch prim => Patch prim wX wY -> Patch prim wX wZ -> Sealed (FL (Patch prim) wY) glump09 p1 p2 = mapSeal (mapFL_FL fromPrim) $ mangleUnravelled $ unseal unravel $ merger "0.0" p1 p2 instance PrimPatch prim => Effect (Patch prim) where effect p@(Merger{}) = sortCoalesceFL $ effect $ mergerUndo p effect p@(Regrem{}) = invert $ effect $ invert p effect (PP p) = p :>: NilFL instance IsHunk prim => IsHunk (Patch prim) where isHunk p = do PP p' <- return p isHunk p' newUr :: PrimPatch prim => Patch prim wA wB -> RL (Patch prim) wX wY -> [Sealed (RL (Patch prim) wX)] newUr p (Merger _ _ p1 p2 :<: ps) = case filter (\(pp:<:_) -> pp `unsafeCompare` p1) $ headPermutationsRL ps of ((_:<:ps'):_) -> newUr p (unsafeCoercePStart p1:<:ps') ++ newUr p (unsafeCoercePStart p2:<:ps') _ -> bugDoc $ text "in function newUr" $$ text "Original patch:" $$ showPatch_ p $$ text "Unwound:" $$ vcat (unseal (mapRL showPatch_) $ unwind p) newUr op ps = case filter (\(p:<:_) -> isMerger p) $ headPermutationsRL ps of [] -> [Sealed ps] (ps':_) -> newUr op ps' instance Invert prim => Invert (Patch prim) where invert (Merger undo unwindings p1 p2) = Regrem undo unwindings p1 p2 invert (Regrem undo unwindings p1 p2) = Merger undo unwindings p1 p2 invert (PP p) = PP (invert p) instance MyEq prim => MyEq (Patch prim) where unsafeCompare = eqPatches instance MyEq prim => Eq (Patch prim wX wY) where (==) = unsafeCompare eqPatches :: MyEq prim => Patch prim wX wY -> Patch prim wW wZ -> Bool eqPatches (PP p1) (PP p2) = unsafeCompare p1 p2 eqPatches (Merger _ _ p1a p1b) (Merger _ _ p2a p2b) = eqPatches p1a p2a && eqPatches p1b p2b eqPatches (Regrem _ _ p1a p1b) (Regrem _ _ p2a p2b) = eqPatches p1a p2a && eqPatches p1b p2b eqPatches _ _ = False