dropdead per-remote metadata

Had to refactor pure code into separate modules so it is accessible
inside Annex.Branch.Transitions.

This commit was sponsored by Peter on Patreon.

Logs/SingleValue.hs

@@ -11,46 +11,20 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-module Logs.SingleValue where
+module Logs.SingleValue (
+	module Logs.SingleValue.Pure,
+	readLog,
+	getLog,
+	setLog,
+) where
 
 import Annex.Common
 import qualified Annex.Branch
-import Logs.Line
+import Logs.SingleValue.Pure
 import Annex.VectorClock
 
 import qualified Data.Set as S
 
-class SingleValueSerializable v where
-	serialize :: v -> String
-	deserialize :: String -> Maybe v
-
-data LogEntry v = LogEntry
-	{ changed :: VectorClock
-	, value :: v
-	} deriving (Eq, Ord)
-
-type Log v = S.Set (LogEntry v)
-
-showLog :: (SingleValueSerializable v) => Log v -> String
-showLog = unlines . map showline . S.toList
-  where
-	showline (LogEntry c v) = unwords [formatVectorClock c, serialize v]
-
-parseLog :: (Ord v, SingleValueSerializable v) => String -> Log v
-parseLog = S.fromList . mapMaybe parse . splitLines
-  where
-	parse line = do
-		let (sc, s) = splitword line
-		c <- parseVectorClock sc
-		v <- deserialize s
-		Just (LogEntry c v)
-	splitword = separate (== ' ')
-
-newestValue :: Log v -> Maybe v
-newestValue s
-	| S.null s = Nothing
-	| otherwise = Just (value $ S.findMax s)
-
 readLog :: (Ord v, SingleValueSerializable v) => FilePath -> Annex (Log v)
 readLog = parseLog <$$> Annex.Branch.get