-- Copyright (C) 2002-2003 David Roundy -- Copyright (C) 2009 Ganesh Sittampalam -- -- 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 #-} {-# LANGUAGE CPP #-} module Darcs.Patch.Permutations ( removeFL, removeRL, removeCommon, commuteWhatWeCanFL, commuteWhatWeCanRL, genCommuteWhatWeCanRL, genCommuteWhatWeCanFL, partitionFL, partitionRL, simpleHeadPermutationsFL, headPermutationsRL, headPermutationsFL, removeSubsequenceFL, removeSubsequenceRL, partitionConflictingFL, inverseCommuter ) where import Data.Maybe ( mapMaybe ) import Darcs.Patch.Commute ( Commute, commute, commuteFLorComplain, commuteRL ) import Darcs.Patch.CommuteFn ( CommuteFn ) import Darcs.Patch.Invert ( Invert(..) ) import Darcs.Patch.Witnesses.Eq ( MyEq(..), EqCheck(..) ) import Darcs.Patch.Witnesses.Ordered ( FL(..), RL(..), (:>)(..), (+<+) , reverseFL, (+>+), (:\/:)(..), lengthFL , lengthRL, reverseRL ) #include "impossible.h" -- |split an 'FL' into "left" and "right" lists according to a predicate @p@, using commutation as necessary. -- If a patch does satisfy the predicate but cannot be commuted past one that does not satisfy -- the predicate, it goes in the "middle" list; to sum up, we have: @all p left@ and @all (not.p) right@, while -- midddle is mixed. -- Note that @p@ should be invariant under commutation (i.e. if 'x1' can commute to 'x2' then 'p x1 <=> p x2'). partitionFL :: Commute p => (forall wU wV . p wU wV -> Bool) -- ^predicate; if true we would like the patch in the "left" list -> FL p wX wY -- ^input 'FL' -> (FL p :> FL p :> FL p) wX wY -- ^"left", "middle" and "right" -- optimise by using an accumulating parameter to track all the "right" patches that we've found so far partitionFL' :: Commute p => (forall wU wV . p wU wV -> Bool) -> RL p wA wB -- the "middle" patches found so far -> RL p wB wC -- the "right" patches found so far -> FL p wC wD -> (FL p :> FL p :> FL p) wA wD partitionFL keepleft = partitionFL' keepleft NilRL NilRL partitionFL' _ middle right NilFL = NilFL :> reverseRL middle :> reverseRL right partitionFL' keepleft middle right (p :>: ps) | keepleft p = case commuteRL (right :> p) of Just (p' :> right') -> case commuteRL (middle :> p') of Just (p'' :> middle') -> case partitionFL' keepleft middle' right' ps of (a :> b :> c) -> p'' :>: a :> b :> c Nothing -> partitionFL' keepleft (p' :<: middle) right' ps Nothing -> case commuteWhatWeCanRL (right :> p) of (tomiddle :> p' :> right') -> partitionFL' keepleft (p' :<: tomiddle +<+ middle) right' ps | otherwise = partitionFL' keepleft middle (p :<: right) ps -- |split an 'RL' into "left" and "right" lists according to a predicate, using commutation as necessary. -- If a patch does satisfy the predicate but cannot be commuted past one that does not satisfy -- the predicate, it goes in the "left" list. partitionRL :: Commute p => (forall wU wV . p wU wV -> Bool) -- ^predicate; if true we would like the patch in the "right" list -> RL p wX wY -- ^input 'RL' -> (RL p :> RL p) wX wY -- ^"left" and "right" results -- optimise by using an accumulating parameter to track all the "left" patches that we've found so far partitionRL' :: Commute p => (forall wU wV . p wU wV -> Bool) -> RL p wX wZ -> FL p wZ wY -- the "left" patches found so far -> (RL p :> RL p) wX wY partitionRL keepright ps = partitionRL' keepright ps NilFL partitionRL' _ NilRL qs = reverseFL qs :> NilRL partitionRL' keepright (p :<: ps) qs | keepright p, Right (qs' :> p') <- commuteFLorComplain (p :> qs) = case partitionRL' keepright ps qs' of a :> b -> a :> p' :<: b | otherwise = partitionRL' keepright ps (p :>: qs) commuteWhatWeCanFL :: Commute p => (p :> FL p) wX wY -> (FL p :> p :> FL p) wX wY commuteWhatWeCanFL = genCommuteWhatWeCanFL commute genCommuteWhatWeCanFL :: Commute q => (forall wA wB . ((p:>q) wA wB -> Maybe ((q:>p)wA wB))) -> (p :> FL q) wX wY -> (FL q :> p :> FL q) wX wY genCommuteWhatWeCanFL com (p :> x :>: xs) = case com (p :> x) of Nothing -> case commuteWhatWeCanFL (x :> xs) of xs1 :> x' :> xs2 -> case genCommuteWhatWeCanFL com (p :> xs1) of xs1' :> p' :> xs2' -> xs1' :> p' :> xs2' +>+ x' :>: xs2 Just (x' :> p') -> case genCommuteWhatWeCanFL com (p' :> xs) of a :> p'' :> c -> x' :>: a :> p'' :> c genCommuteWhatWeCanFL _ (y :> NilFL) = NilFL :> y :> NilFL commuteWhatWeCanRL :: Commute p => (RL p :> p) wX wY -> (RL p :> p :> RL p) wX wY commuteWhatWeCanRL = genCommuteWhatWeCanRL commute genCommuteWhatWeCanRL :: Commute p => (forall wA wB . ((p :> q) wA wB -> Maybe ((q :> p) wA wB))) -> (RL p :> q) wX wY -> (RL p :> q :> RL p) wX wY genCommuteWhatWeCanRL com (x :<: xs :> p) = case com (x :> p) of Nothing -> case commuteWhatWeCanRL (xs :> x) of xs1 :> x' :> xs2 -> case genCommuteWhatWeCanRL com (xs2 :> p) of xs1' :> p' :> xs2' -> xs1' +<+ x' :<: xs1 :> p' :> xs2' Just (p' :> x') -> case genCommuteWhatWeCanRL com (xs :> p') of a :> p'' :> c -> a :> p'' :> x' :<: c genCommuteWhatWeCanRL _ (NilRL :> y) = NilRL :> y :> NilRL removeCommon :: (MyEq p, Commute p) => (FL p :\/: FL p) wX wY -> (FL p :\/: FL p) wX wY removeCommon (xs :\/: NilFL) = xs :\/: NilFL removeCommon (NilFL :\/: xs) = NilFL :\/: xs removeCommon (xs :\/: ys) = rc xs (headPermutationsFL ys) where rc :: (MyEq p, Commute p) => FL p wX wY -> [(p:>FL p) wX wZ] -> (FL p :\/: FL p) wY wZ rc nms ((n:>ns):_) | Just ms <- removeFL n nms = removeCommon (ms :\/: ns) rc ms [n:>ns] = ms :\/: n:>:ns rc ms (_:nss) = rc ms nss rc _ [] = impossible -- because we already checked for NilFL case -- | 'removeFL' @x xs@ removes @x@ from @xs@ if @x@ can be commuted to its head. -- Otherwise it returns 'Nothing' removeFL :: (MyEq p, Commute p) => p wX wY -> FL p wX wZ -> Maybe (FL p wY wZ) removeFL x xs = r x $ headPermutationsFL xs where r :: (MyEq p, Commute p) => p wX wY -> [(p:>FL p) wX wZ] -> Maybe (FL p wY wZ) r _ [] = Nothing r z ((z':>zs):zss) | IsEq <- z =\/= z' = Just zs | otherwise = r z zss -- | 'removeRL' is like 'removeFL' except with 'RL' removeRL :: (MyEq p, Commute p) => p wY wZ -> RL p wX wZ -> Maybe (RL p wX wY) removeRL x xs = r x $ headPermutationsRL xs where r :: (MyEq p, Commute p) => p wY wZ -> [RL p wX wZ] -> Maybe (RL p wX wY) r z ((z':<:zs):zss) | IsEq <- z =/\= z' = Just zs | otherwise = r z zss r _ _ = Nothing -- | 'removeSubsequenceFL' @ab abc@ returns @Just c'@ where all the patches in -- @ab@ have been commuted out of it, if possible. If this is not possible -- for any reason (the set of patches @ab@ is not actually a subset of @abc@, -- or they can't be commuted out) we return 'Nothing'. removeSubsequenceFL :: (MyEq p, Commute p) => FL p wA wB -> FL p wA wC -> Maybe (FL p wB wC) removeSubsequenceFL a b | lengthFL a > lengthFL b = Nothing | otherwise = rsFL a b where rsFL :: (MyEq p, Commute p) => FL p wA wB -> FL p wA wC -> Maybe (FL p wB wC) rsFL NilFL ys = Just ys rsFL (x:>:xs) yys = removeFL x yys >>= removeSubsequenceFL xs -- | 'removeSubsequenceRL' is like @removeSubsequenceFL@ except that it works -- on 'RL' removeSubsequenceRL :: (MyEq p, Commute p) => RL p wAb wAbc -> RL p wA wAbc -> Maybe (RL p wA wAb) removeSubsequenceRL a b | lengthRL a > lengthRL b = Nothing | otherwise = rsRL a b where rsRL :: (MyEq p, Commute p) => RL p wAb wAbc -> RL p wA wAbc -> Maybe (RL p wA wAb) rsRL NilRL ys = Just ys rsRL (x:<:xs) yys = removeRL x yys >>= removeSubsequenceRL xs -- | This is a minor variant of 'headPermutationsFL' with each permutation -- is simply returned as a 'FL' simpleHeadPermutationsFL :: Commute p => FL p wX wY -> [FL p wX wY] simpleHeadPermutationsFL ps = map (\ (x:>xs) -> x:>:xs) $ headPermutationsFL ps -- | 'headPermutationsFL' @p:>:ps@ returns all the permutations of the list -- in which one element of @ps@ is commuted past @p@ -- -- Suppose we have a sequence of patches -- -- > X h a y s-t-c k -- -- Suppose furthermore that the patch @c@ depends on @t@, which in turn -- depends on @s@. This function will return -- -- > X :> h a y s t c k -- > h :> X a y s t c k -- > a :> X h y s t c k -- > y :> X h a s t c k -- > s :> X h a y t c k -- > k :> X h a y s t c headPermutationsFL :: Commute p => FL p wX wY -> [(p :> FL p) wX wY] headPermutationsFL NilFL = [] headPermutationsFL (p:>:ps) = (p:>ps) : mapMaybe (swapfirstFL.(p:>)) (headPermutationsFL ps) where swapfirstFL (p1:>p2:>xs) = do p2':>p1' <- commute (p1:>p2) Just $ p2':>p1':>:xs -- | 'headPermutationsRL' is like 'headPermutationsFL', except that we -- operate on an 'RL' (in other words, we are pushing things to the end of a -- patch sequence instead of to the beginning). headPermutationsRL :: Commute p => RL p wX wY -> [RL p wX wY] headPermutationsRL NilRL = [] headPermutationsRL (p:<:ps) = (p:<:ps) : mapMaybe (swapfirstRL.(p:<:)) (headPermutationsRL ps) where swapfirstRL (p1:<:p2:<:xs) = do p1':>p2' <- commute (p2:>p1) Just $ p2':<:p1':<:xs swapfirstRL _ = Nothing instance (MyEq p, Commute p) => MyEq (FL p) where a =\/= b | lengthFL a /= lengthFL b = NotEq | otherwise = cmpSameLength a b where cmpSameLength :: FL p wX wY -> FL p wX wZ -> EqCheck wY wZ cmpSameLength (x:>:xs) xys | Just ys <- removeFL x xys = cmpSameLength xs ys cmpSameLength NilFL NilFL = IsEq cmpSameLength _ _ = NotEq xs =/\= ys = reverseFL xs =/\= reverseFL ys instance (MyEq p, Commute p) => MyEq (RL p) where unsafeCompare = bug "Buggy use of unsafeCompare on RL" a =/\= b | lengthRL a /= lengthRL b = NotEq | otherwise = cmpSameLength a b where cmpSameLength :: RL p wX wY -> RL p wW wY -> EqCheck wX wW cmpSameLength (x:<:xs) xys | Just ys <- removeRL x xys = cmpSameLength xs ys cmpSameLength NilRL NilRL = IsEq cmpSameLength _ _ = NotEq xs =\/= ys = reverseRL xs =\/= reverseRL ys -- |Partition a list into the patches that merge with the given patch and those that don't (including dependencies) partitionConflictingFL :: (Commute p1, Invert p1) => CommuteFn p1 p2 -> FL p1 wX wY -> p2 wX wZ -> (FL p1 :> FL p1) wX wY partitionConflictingFL _ NilFL _ = NilFL :> NilFL partitionConflictingFL commuter (x :>: xs) y = case commuter (invert x :> y) of Nothing -> case commuteWhatWeCanFL (x :> xs) of xs_ok :> x' :> xs_deps -> case partitionConflictingFL commuter xs_ok y of xs_clean :> xs_conflicts -> xs_clean :> (xs_conflicts +>+ (x' :>: xs_deps)) Just (y' :> _) -> case partitionConflictingFL commuter xs y' of xs_clean :> xs_conflicts -> (x :>: xs_clean) :> xs_conflicts inverseCommuter :: (Invert p, Invert q) => CommuteFn p q -> CommuteFn q p inverseCommuter commuter (p :> q) = do invp' :> invq' <- commuter (invert q :> invert p) return (invert invq' :> invert invp')