clean up read/show abuse

Avoid ever using read to parse a non-haskell formatted input string.

show :: Key is arguably still show abuse, but displaying Keys as filenames
is just too useful to give up.

Logs/Location.hs

@@ -37,7 +37,7 @@ logChange repo _ NoUUID _ = error $
 {- Returns a list of repository UUIDs that, according to the log, have
  - the value of a key. -}
 keyLocations :: Key -> Annex [UUID]
-keyLocations key = map read <$> (currentLog . logFile) key
+keyLocations key = map toUUID <$> (currentLog . logFile) key
 
 {- Finds all keys that have location log information.
  - (There may be duplicate keys in the list.) -}

Logs/Presence.hs

@@ -16,6 +16,7 @@ module Logs.Presence (
 	addLog,
 	readLog,
 	parseLog,
+	showLog,
 	logNow,
 	compactLog,
 	currentLog,
@@ -36,41 +37,9 @@ data LogLine = LogLine {
 	info :: String
 } deriving (Eq)
 
-data LogStatus = InfoPresent | InfoMissing | Undefined
+data LogStatus = InfoPresent | InfoMissing
 	deriving (Eq)
 
-instance Show LogStatus where
-	show InfoPresent = "1"
-	show InfoMissing = "0"
-	show Undefined = "undefined"
-
-instance Read LogStatus where
-	readsPrec _ "1" = [(InfoPresent, "")]
-	readsPrec _ "0" = [(InfoMissing, "")]
-	readsPrec _ _   = [(Undefined, "")]
-
-instance Show LogLine where
-	show (LogLine d s i) = unwords [show d, show s, i]
-
-instance Read LogLine where
-	-- This parser is robust in that even unparsable log lines are
-	-- read without an exception being thrown.
-	-- Such lines have a status of Undefined.
-	readsPrec _ string = 
-		if length w >= 3
-			then maybe bad good pdate
-			else bad
-		where
-			w = words string
-			s = read $ w !! 1
-			i = w !! 2
-			pdate :: Maybe UTCTime
-			pdate = parseTime defaultTimeLocale "%s%Qs" $ head w
-
-			good v = ret $ LogLine (utcTimeToPOSIXSeconds v) s i
-			bad = ret $ LogLine 0 Undefined ""
-			ret v = [(v, "")]
-
 addLog :: FilePath -> LogLine -> Annex ()
 addLog file line = Annex.Branch.change file $ \s -> 
 	showLog $ compactLog (line : parseLog s)
@@ -80,15 +49,26 @@ addLog file line = Annex.Branch.change file $ \s ->
 readLog :: FilePath -> Annex [LogLine]
 readLog file = parseLog <$> Annex.Branch.get file
 
+{- Parses a log file. Unparseable lines are ignored. -}
 parseLog :: String -> [LogLine]
-parseLog = filter parsable . map read . lines
+parseLog = mapMaybe (parseline . words) . lines
 	where
-		-- some lines may be unparseable, avoid them
-		parsable l = status l /= Undefined
+		parseline (a:b:c:_) = do
+			d <- parseTime defaultTimeLocale "%s%Qs" a
+			s <- parsestatus b
+			Just $ LogLine (utcTimeToPOSIXSeconds d) s c
+		parseline _ = Nothing
+		parsestatus "1" = Just InfoPresent
+		parsestatus "0" = Just InfoMissing
+		parsestatus _ = Nothing
 
 {- Generates a log file. -}
 showLog :: [LogLine] -> String
-showLog = unlines . map show
+showLog = unlines . map genline
+	where
+		genline (LogLine d s i) = unwords [show d, genstatus s, i]
+		genstatus InfoPresent = "1"
+		genstatus InfoMissing = "0"
 
 {- Generates a new LogLine with the current date. -}
 logNow :: LogStatus -> String -> Annex LogLine

Logs/Trust.hs

@@ -45,18 +45,26 @@ trustMap = do
 
 parseTrust :: String -> Maybe TrustLevel
 parseTrust s
-	| length w > 0 = readMaybe $ head w
+	| length w > 0 = Just $ parse $ head w
 	-- back-compat; the trust.log used to only list trusted repos
-	| otherwise = Just Trusted
+	| otherwise = Just $ Trusted
 	where
 		w = words s
+		parse "1" = Trusted
+		parse "0" = UnTrusted
+		parse _ = SemiTrusted
+
+showTrust :: TrustLevel -> String
+showTrust SemiTrusted = "?"
+showTrust UnTrusted = "0"
+showTrust Trusted = "1"
 
 {- Changes the trust level for a uuid in the trustLog. -}
 trustSet :: UUID -> TrustLevel -> Annex ()
 trustSet uuid@(UUID _) level = do
 	ts <- liftIO $ getPOSIXTime
 	Annex.Branch.change trustLog $
-		showLog show . changeLog ts uuid level . parseLog parseTrust
+		showLog showTrust . changeLog ts uuid level . parseLog parseTrust
 	Annex.changeState $ \s -> s { Annex.trustmap = Nothing }
 trustSet NoUUID _ = error "unknown UUID; cannot modify trust level"
 

Logs/UUIDBased.hs

@@ -50,28 +50,27 @@ showLog :: (a -> String) -> Log a -> String
 showLog shower = unlines . map showpair . M.toList
 	where
 		showpair (k, LogEntry (Date p) v) =
-			unwords [show k, shower v, tskey ++ show p]
+			unwords [fromUUID k, shower v, tskey ++ show p]
 		showpair (k, LogEntry Unknown v) =
-			unwords [show k, shower v]
+			unwords [fromUUID k, shower v]
 
 parseLog :: (String -> Maybe a) -> String -> Log a
-parseLog parser = M.fromListWith best . catMaybes . map pair . lines
+parseLog parser = M.fromListWith best . catMaybes . map parse . lines
 	where
-		pair line
+		parse line
 			| null ws = Nothing
-			| otherwise = case parser $ unwords info of
-				Nothing -> Nothing
-				Just v -> Just (read u, LogEntry c v)
+			| otherwise = parser (unwords info) >>= makepair
 			where
+				makepair v = Just (toUUID u, LogEntry ts v)
 				ws = words line
 				u = head ws
 				end = last ws
-				c
+				ts
 					| tskey `isPrefixOf` end =
 						pdate $ tail $ dropWhile (/= '=') end
 					| otherwise = Unknown
 				info
-					| c == Unknown = drop 1 ws
+					| ts == Unknown = drop 1 ws
 					| otherwise = drop 1 $ init ws
 				pdate s = case parseTime defaultTimeLocale "%s%Qs" s of
 					Nothing -> Unknown