added preferred-content log, and allow editing it with vicfg

This includes a full parser for the boolean expressions in the log,
that compiles them into Matchers. Those matchers are not used yet.

A complication is that matching against an expression should never
crash git-annex with an error. Instead, vicfg checks that the expressions
parse. If a bad expression (or an expression understood by some future
git-annex version) gets into the log, it'll be ignored.

Most of the code in Limit couldn't fail anyway, but I did have to make
limitCopies check its parameter first, and return an error if it's bad,
rather than erroring at runtime.

9 files changed, 193 insertions, 33 deletions

diff --git a/Annex.hs b/Annex.hs
index 87edb7c13..572823497 100644
--- a/Annex.hs
+++ b/Annex.hs
@@ -10,6 +10,7 @@
 module Annex (
 	Annex,
 	AnnexState(..),
+	PreferredContentMap,
 	new,
 	newState,
 	run,
@@ -47,6 +48,7 @@ import Types.BranchState
 import Types.TrustLevel
 import Types.Group
 import Types.Messages
+import Types.UUID
 import Utility.State
 import qualified Utility.Matcher
 import qualified Data.Map as M
@@ -74,6 +76,8 @@ instance MonadBaseControl IO Annex where
 
 type Matcher a = Either [Utility.Matcher.Token a] (Utility.Matcher.Matcher a)
 
+type PreferredContentMap = M.Map UUID (Utility.Matcher.Matcher (FilePath -> Annex Bool))
+
 -- internal state storage
 data AnnexState = AnnexState
 	{ repo :: Git.Repo
@@ -90,6 +94,7 @@ data AnnexState = AnnexState
 	, forcebackend :: Maybe String
 	, forcenumcopies :: Maybe Int
 	, limit :: Matcher (FilePath -> Annex Bool)
+	, preferredcontentmap :: Maybe PreferredContentMap
 	, shared :: Maybe SharedRepository
 	, forcetrust :: TrustMap
 	, trustmap :: Maybe TrustMap
@@ -117,6 +122,7 @@ newState gitrepo = AnnexState
 	, forcebackend = Nothing
 	, forcenumcopies = Nothing
 	, limit = Left []
+	, preferredcontentmap = Nothing
 	, shared = Nothing
 	, forcetrust = M.empty
 	, trustmap = Nothing
diff --git a/Command/Vicfg.hs b/Command/Vicfg.hs
index d44967b28..31b8f6f01 100644
--- a/Command/Vicfg.hs
+++ b/Command/Vicfg.hs
@@ -20,6 +20,7 @@ import Types.TrustLevel
 import Types.Group
 import Logs.Trust
 import Logs.Group
+import Logs.PreferredContent
 import Remote
 
 def :: [Command]
@@ -55,6 +56,7 @@ vicfg curcfg f = do
 data Cfg = Cfg
 	{ cfgTrustMap :: TrustMap
 	, cfgGroupMap :: M.Map UUID (S.Set Group)
+	, cfgPreferredContentMap :: M.Map UUID String
 	, cfgDescriptions :: M.Map UUID String
 	}
 
@@ -62,26 +64,29 @@ getCfg :: Annex Cfg
 getCfg = Cfg
 	<$> trustMapRaw -- without local trust overrides
 	<*> (groupsByUUID <$> groupMap)
+	<*> preferredContentMapRaw
 	<*> uuidDescriptions
 
-emptyCfg :: Cfg
-emptyCfg = Cfg M.empty M.empty M.empty
-
 setCfg :: Cfg -> Cfg -> Annex ()
 setCfg curcfg newcfg = do
-	let (trustchanges, groupchanges) = diffCfg curcfg newcfg
-	mapM_ (\(u,t) -> trustSet u t) $ M.toList trustchanges
-	mapM_ (\(u, gs) -> groupChange u $ const gs) $ M.toList groupchanges
+	let (trustchanges, groupchanges, preferredcontentchanges) = diffCfg curcfg newcfg
+	mapM_ (uncurry trustSet) $ M.toList trustchanges
+	mapM_ (uncurry groupSet) $ M.toList groupchanges
+	mapM_ (uncurry preferredContentSet) $ M.toList preferredcontentchanges
 
-diffCfg :: Cfg -> Cfg -> (TrustMap, M.Map UUID (S.Set Group))
-diffCfg curcfg newcfg = (diff cfgTrustMap, diff cfgGroupMap)
+diffCfg :: Cfg -> Cfg -> (TrustMap, M.Map UUID (S.Set Group), M.Map UUID String)
+diffCfg curcfg newcfg = (diff cfgTrustMap, diff cfgGroupMap, diff cfgPreferredContentMap)
 	where
 		diff f = M.differenceWith (\x y -> if x == y then Nothing else Just x)
 			(f newcfg) (f curcfg)
 
 genCfg :: Cfg -> String
 genCfg cfg = unlines $ concat
-	[intro, trustintro, trust, defaulttrust, groupsintro, groups, defaultgroups]
+	[ intro
+	, trustintro, trust, defaulttrust
+	, groupsintro, groups, defaultgroups
+	, preferredcontentintro, preferredcontent, defaultpreferredcontent
+	]
 	where
 		intro =
 			[ com "git-annex configuration"
@@ -91,6 +96,7 @@ genCfg cfg = unlines $ concat
 			, com "Lines in this file have the format:"
 			, com "  setting repo = value"
 			]
+
 		trustintro =
 			[ ""
 			, com "Repository trust configuration"
@@ -100,6 +106,7 @@ genCfg cfg = unlines $ concat
 			]
 		trust = map (\(t, u) -> line "trust" u $ showTrustLevel t) $
 			sort $ map swap $ M.toList $ cfgTrustMap cfg
+
 		defaulttrust = map (\u -> pcom $ line "trust" u $ showTrustLevel SemiTrusted) $
 			missing cfgTrustMap
 		groupsintro = 
@@ -112,6 +119,15 @@ genCfg cfg = unlines $ concat
 		defaultgroups = map (\u -> pcom $ line "group" u "") $
 			missing cfgGroupMap
 
+		preferredcontentintro = 
+			[ ""
+			, com "Repository preferred contents"
+			]
+		preferredcontent = sort $ map (\(s, u) -> line "preferred-content" u s) $
+			map swap $ M.toList $ cfgPreferredContentMap cfg
+		defaultpreferredcontent = map (\u -> pcom $ line "preferred-content" u "") $
+			missing cfgPreferredContentMap
+
 		line setting u value = unwords
 			[ setting
 			, showu u
@@ -160,6 +176,12 @@ parseCfg curcfg = go [] curcfg . lines
 			| setting == "group" =
 				let m = M.insert u (S.fromList $ words value) (cfgGroupMap cfg)
 				in Right $ cfg { cfgGroupMap = m }
+			| setting == "preferred-content" = 
+				case checkPreferredContentExpression value of
+					Just e -> Left e
+					Nothing ->
+						let m = M.insert u value (cfgPreferredContentMap cfg)
+						in Right $ cfg { cfgPreferredContentMap = m }
 			| otherwise = badval "setting" setting
 
 		name2uuid = M.fromList $ map swap $
diff --git a/Limit.hs b/Limit.hs
index dd512689f..89156a783 100644
--- a/Limit.hs
+++ b/Limit.hs
@@ -1,6 +1,6 @@
 {- user-specified limits on files to act on
  -
- - Copyright 2011 Joey Hess <joey@kitenet.net>
+ - Copyright 2011,2012 Joey Hess <joey@kitenet.net>
  -
  - Licensed under the GNU GPL version 3 or higher.
  -}
@@ -24,6 +24,7 @@ import Logs.Group
 import Utility.HumanTime
 
 type Limit = Utility.Matcher.Token (FilePath -> Annex Bool)
+type MkLimit = String -> Either String (FilePath -> Annex Bool)
 
 {- Checks if there are user-specified limits. -}
 limited :: Annex Bool
@@ -56,16 +57,22 @@ addToken :: String -> Annex ()
 addToken = add . Utility.Matcher.token
 
 {- Adds a new limit. -}
-addLimit :: (FilePath -> Annex Bool) -> Annex ()
-addLimit = add . Utility.Matcher.Operation
+addLimit :: Either String (FilePath -> Annex Bool) -> Annex ()
+addLimit = either error (add . Utility.Matcher.Operation)
 
 {- Add a limit to skip files that do not match the glob. -}
 addInclude :: String -> Annex ()
-addInclude glob = addLimit $ return . matchglob glob
+addInclude = addLimit . limitInclude
+
+limitInclude :: MkLimit
+limitInclude glob = Right $ return . matchglob glob
 
 {- Add a limit to skip files that match the glob. -}
 addExclude :: String -> Annex ()
-addExclude glob = addLimit $ return . not . matchglob glob
+addExclude = addLimit . limitExclude
+
+limitExclude :: MkLimit
+limitExclude glob = Right $ return . not . matchglob glob
 
 matchglob :: String -> FilePath -> Bool
 matchglob glob f = isJust $ match cregex f []
@@ -76,7 +83,10 @@ matchglob glob f = isJust $ match cregex f []
 {- Adds a limit to skip files not believed to be present
  - in a specfied repository. -}
 addIn :: String -> Annex ()
-addIn name = addLimit $ check $ if name == "." then inAnnex else inremote
+addIn = addLimit . limitIn
+
+limitIn :: MkLimit
+limitIn name = Right $ check $ if name == "." then inAnnex else inremote
 	where
 		check a = Backend.lookupFile >=> handle a
 		handle _ Nothing = return False
@@ -89,18 +99,22 @@ addIn name = addLimit $ check $ if name == "." then inAnnex else inremote
 {- Adds a limit to skip files not believed to have the specified number
  - of copies. -}
 addCopies :: String -> Annex ()
-addCopies want = addLimit . check $ readnum num
+addCopies = addLimit . limitCopies
+
+limitCopies :: MkLimit
+limitCopies want = case split ":" want of
+	[v, n] -> case readTrustLevel v of
+		Just trust -> go n $ checktrust trust
+		Nothing -> go n $ checkgroup v
+	[n] -> go n $ const $ return True
+	_ -> Left "bad value for copies"
 	where
-		(num, good) = case split ":" want of
-			[v, n] -> case readTrustLevel v of
-				Just trust -> (n, checktrust trust)
-				Nothing -> (n, checkgroup v)
-			[n] -> (n, const $ return True)
-			_ -> error "bad value for --copies"
-		readnum = maybe (error "bad number for --copies") id . readish
-		check n = Backend.lookupFile >=> handle n
-		handle _ Nothing = return False
-		handle n (Just (key, _)) = do
+		go num good = case readish num of
+			Nothing -> Left "bad number for copies"
+			Just n -> Right $ check n good
+		check n good = Backend.lookupFile >=> handle n good
+		handle _ _ Nothing = return False
+		handle n good (Just (key, _)) = do
 			us <- filterM good =<< Remote.keyLocations key
 			return $ length us >= n
 		checktrust t u = (== t) <$> lookupTrust u
@@ -108,7 +122,10 @@ addCopies want = addLimit . check $ readnum num
 
 {- Adds a limit to skip files not using a specified key-value backend. -}
 addInBackend :: String -> Annex ()
-addInBackend name = addLimit $ Backend.lookupFile >=> check
+addInBackend = addLimit . limitInBackend
+
+limitInBackend :: MkLimit
+limitInBackend name = Right $ Backend.lookupFile >=> check
 	where
 		wanted = Backend.lookupBackendName name
 		check = return . maybe False ((==) wanted . snd)
@@ -118,11 +135,10 @@ addTimeLimit s = do
 	let seconds = fromMaybe (error "bad time-limit") $ parseDuration s
 	start <- liftIO getPOSIXTime
 	let cutoff = start + seconds
-	addLimit $ const $ do
+	addLimit $ Right $ const $ do
 		now <- liftIO getPOSIXTime
 		if now > cutoff
 			then do
 				warning $ "Time limit (" ++ s ++ ") reached!"
 				liftIO $ exitWith $ ExitFailure 101
 			else return True
-		
diff --git a/Logs/Group.hs b/Logs/Group.hs
index 59f48f3a3..09d431e63 100644
--- a/Logs/Group.hs
+++ b/Logs/Group.hs
@@ -7,6 +7,7 @@
 
 module Logs.Group (
 	groupChange,
+	groupSet,
 	lookupGroups,
 	groupMap,
 ) where
@@ -39,7 +40,10 @@ groupChange uuid@(UUID _) modifier = do
 			changeLog ts uuid (modifier curr) .
 				parseLog (Just . S.fromList . words)
 	Annex.changeState $ \s -> s { Annex.groupmap = Nothing }
-groupChange NoUUID _ = error "unknown UUID; cannot modify group"
+groupChange NoUUID _ = error "unknown UUID; cannot modify"
+
+groupSet :: UUID -> S.Set Group -> Annex ()
+groupSet u g = groupChange u (const g)
 
 {- Read the groupLog into a map. The map is cached for speed. -}
 groupMap :: Annex GroupMap
diff --git a/Logs/PreferredContent.hs b/Logs/PreferredContent.hs
new file mode 100644
index 000000000..f482ac57b
--- /dev/null
+++ b/Logs/PreferredContent.hs
@@ -0,0 +1,93 @@
+{- git-annex preferred content matcher configuration
+ -
+ - Copyright 2012 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Logs.PreferredContent (
+	preferredContentSet,
+	preferredContentMap,
+	preferredContentMapRaw,
+	checkPreferredContentExpression,
+) where
+
+import qualified Data.Map as M
+import Data.Either
+import Data.Time.Clock.POSIX
+
+import Common.Annex
+import qualified Annex.Branch
+import qualified Annex
+import Logs.UUIDBased
+import Limit (limitInclude, limitExclude, limitIn, limitCopies, limitInBackend)
+import qualified Utility.Matcher
+
+{- Filename of preferred-content.log. -}
+preferredContentLog :: FilePath
+preferredContentLog = "preferred-content.log"
+
+{- Changes the preferred content configuration of a remote. -}
+preferredContentSet :: UUID -> String -> Annex ()
+preferredContentSet uuid@(UUID _) val = do
+	ts <- liftIO getPOSIXTime
+	Annex.Branch.change preferredContentLog $
+		showLog id . changeLog ts uuid val . parseLog Just
+	Annex.changeState $ \s -> s { Annex.groupmap = Nothing }
+preferredContentSet NoUUID _ = error "unknown UUID; cannot modify"
+
+{- Read the preferredContentLog into a map. The map is cached for speed. -}
+preferredContentMap :: Annex Annex.PreferredContentMap
+preferredContentMap = do
+	cached <- Annex.getState Annex.preferredcontentmap
+	case cached of
+		Just m -> return m
+		Nothing -> do
+			m <- simpleMap . parseLog (Just . makeMatcher)
+				<$> Annex.Branch.get preferredContentLog
+			Annex.changeState $ \s -> s { Annex.preferredcontentmap = Just m }
+			return m
+
+preferredContentMapRaw :: Annex (M.Map UUID String)
+preferredContentMapRaw = simpleMap . parseLog Just
+	<$> Annex.Branch.get preferredContentLog
+
+{- This intentionally never fails, even on unparsable expressions,
+ - because the configuration is shared amoung repositories and newer
+ - versions of git-annex may add new features. Instead, parse errors
+ - result in a Matcher that will always succeed. -}
+makeMatcher :: String -> Utility.Matcher.Matcher (FilePath -> Annex Bool)
+makeMatcher s
+	| null (lefts tokens) =  Utility.Matcher.generate $ rights tokens
+ 	| otherwise = Utility.Matcher.generate []
+	where
+		tokens = map parseToken $ tokenizeMatcher s
+
+{- Checks if an expression can be parsed, if not returns Just error -}
+checkPreferredContentExpression :: String -> Maybe String
+checkPreferredContentExpression s = case lefts $ map parseToken $ tokenizeMatcher s of
+	[] -> Nothing
+	l -> Just $ unwords $ map ("Parse failure: " ++) l
+
+parseToken :: String -> Either String (Utility.Matcher.Token (FilePath -> Annex Bool))
+parseToken t
+	| any (== t) Utility.Matcher.tokens = Right $ Utility.Matcher.token t
+	| otherwise = maybe (Left $ "near " ++ show t) use $ M.lookup k m
+	where
+		(k, v) = separate (== '=') t
+		m = M.fromList
+			[ ("include", limitInclude)
+			, ("exclude", limitExclude)
+			, ("in", limitIn)
+			, ("copies", limitCopies)
+			, ("backend", limitInBackend)
+			]
+		use a = Utility.Matcher.Operation <$> a v
+
+{- This is really dumb tokenization; there's no support for quoted values.
+ - Open and close parens are always treated as standalone tokens;
+ - otherwise tokens must be separated by whitespace. -}
+tokenizeMatcher :: String -> [String]
+tokenizeMatcher = filter (not . null ) . concatMap splitparens . words
+	where
+		splitparens = segmentDelim (`elem` "()")
diff --git a/Logs/Trust.hs b/Logs/Trust.hs
index ce7615ba5..1a29f8cf0 100644
--- a/Logs/Trust.hs
+++ b/Logs/Trust.hs
@@ -46,7 +46,7 @@ trustSet uuid@(UUID _) level = do
 			changeLog ts uuid level .
 				parseLog (Just . parseTrustLog)
 	Annex.changeState $ \s -> s { Annex.trustmap = Nothing }
-trustSet NoUUID _ = error "unknown UUID; cannot modify trust level"
+trustSet NoUUID _ = error "unknown UUID; cannot modify"
 
 {- Returns the TrustLevel of a given repo UUID. -}
 lookupTrust :: UUID -> Annex TrustLevel
diff --git a/Utility/Matcher.hs b/Utility/Matcher.hs
index 9b6005767..83a2b1d61 100644
--- a/Utility/Matcher.hs
+++ b/Utility/Matcher.hs
@@ -19,6 +19,7 @@ module Utility.Matcher (
 	Token(..),
 	Matcher,
 	token,
+	tokens,
 	generate,
 	match,
 	matchM,
@@ -48,6 +49,9 @@ token "(" = Open
 token ")" = Close
 token t = error $ "unknown token " ++ t
 
+tokens :: [String]
+tokens = words "and or not ( )"
+
 {- Converts a list of Tokens into a Matcher. -}
 generate :: [Token op] -> Matcher op
 generate = go MAny
diff --git a/Utility/Misc.hs b/Utility/Misc.hs
index 349b20efe..88d210de6 100644
--- a/Utility/Misc.hs
+++ b/Utility/Misc.hs
@@ -42,11 +42,15 @@ firstLine = takeWhile (/= '\n')
 {- Splits a list into segments that are delimited by items matching
  - a predicate. (The delimiters are not included in the segments.) -}
 segment :: (a -> Bool) -> [a] -> [[a]]
-segment p l = map reverse $ go [] [] l
+segment p = filter (not . all p) . segmentDelim p
+
+{- Includes the delimiters as segments of their own. -}
+segmentDelim :: (a -> Bool) -> [a] -> [[a]]
+segmentDelim p l = map reverse $ go [] [] l
 	where
 		go c r [] = reverse $ c:r
 		go c r (i:is)
-			| p i = go [] (c:r) is
+			| p i = go [] ([i]:c:r) is
 			| otherwise = go (i:c) r is
 
 {- Given two orderings, returns the second if the first is EQ and returns
diff --git a/doc/internals.mdwn b/doc/internals.mdwn
index 26e1d2fc2..89940ba6a 100644
--- a/doc/internals.mdwn
+++ b/doc/internals.mdwn
@@ -75,6 +75,17 @@ The file format is one line per repository, with the uuid followed by a space,
 and then a space-separated list of groups this repository is part of,
 and finally a timestamp.
 
+## `preferred-content.log`
+
+Used to indicate which repositories prefer to contain which file contents.
+
+The file format is one line per repository, with the uuid followed by a space,
+then a boolean expression, and finally a timestamp.
+
+Files matching the expression are preferred to be retained in the
+repository, while files not matching it are preferred to be stored
+somewhere else.
+
 ## `aaa/bbb/*.log`
 
 These log files record [[location_tracking]] information