vicfg: Deleting configurations now resets to the default, where before it has no effect.

Added a Default instance for TrustLevel, and was able to use that to clear
up several other parts of the code too.

This commit was sponsored by Stephan Schulz

Annex/Branch/Transitions.hs

@@ -19,6 +19,7 @@ import Types.TrustLevel
 import Types.UUID
 
 import qualified Data.Map as M
+import Data.Default
 
 data FileTransition
 	= ChangeFile String
@@ -60,4 +61,4 @@ dropDeadFromPresenceLog :: TrustMap -> [Presence.LogLine] -> [Presence.LogLine]
 dropDeadFromPresenceLog trustmap = filter $ notDead trustmap (toUUID . Presence.info)
 
 notDead :: TrustMap -> (v -> UUID) -> v -> Bool
-notDead trustmap a v = M.findWithDefault SemiTrusted (a v) trustmap /= DeadTrusted
+notDead trustmap a v = M.findWithDefault def (a v) trustmap /= DeadTrusted

Command/Vicfg.hs

@@ -5,6 +5,8 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
+{-# LANGUAGE RankNTypes #-}
+
 module Command.Vicfg where
 
 import qualified Data.Map as M
@@ -12,6 +14,7 @@ import qualified Data.Set as S
 import System.Environment (getEnv)
 import Data.Tuple (swap)
 import Data.Char (isSpace)
+import Data.Default
 
 import Common.Annex
 import Command
@@ -49,7 +52,7 @@ vicfg curcfg f = do
 	-- Allow EDITOR to be processed by the shell, so it can contain options.
 	unlessM (liftIO $ boolSystem "sh" [Param "-c", Param $ unwords [vi, shellEscape f]]) $
 		error $ vi ++ " exited nonzero; aborting"
-	r <- parseCfg curcfg <$> liftIO (readFileStrict f)
+	r <- parseCfg (defCfg curcfg) <$> liftIO (readFileStrict f)
 	liftIO $ nukeFile f
 	case r of
 		Left s -> do
@@ -85,6 +88,21 @@ setCfg curcfg newcfg = do
 	mapM_ (uncurry groupPreferredContentSet) $ M.toList $ cfgGroupPreferredContentMap diff
 	mapM_ (uncurry scheduleSet) $ M.toList $ cfgScheduleMap diff
 
+{- Default config has all the keys from the input config, but with their
+ - default values. -}
+defCfg :: Cfg -> Cfg
+defCfg curcfg = Cfg
+	{ cfgTrustMap = mapdef $ cfgTrustMap curcfg
+	, cfgGroupMap = mapdef $ cfgGroupMap curcfg
+	, cfgPreferredContentMap = mapdef $ cfgPreferredContentMap curcfg
+	, cfgRequiredContentMap = mapdef $ cfgRequiredContentMap curcfg
+	, cfgGroupPreferredContentMap = mapdef $ cfgGroupPreferredContentMap curcfg
+	, cfgScheduleMap = mapdef $ cfgScheduleMap curcfg
+	}
+  where
+	mapdef :: forall k v. Default v => M.Map k v -> M.Map k v
+	mapdef = M.map (const Data.Default.def)
+
 diffCfg :: Cfg -> Cfg -> Cfg
 diffCfg curcfg newcfg = Cfg
 	{ cfgTrustMap = diff cfgTrustMap
@@ -124,7 +142,7 @@ genCfg cfg descs = unlines $ intercalate [""]
 		, com "(Valid trust levels: " ++ trustlevels ++ ")"
 		]
 		(\(t, u) -> line "trust" u $ showTrustLevel t)
-		(\u -> lcom $ line "trust" u $ showTrustLevel SemiTrusted)
+		(\u -> lcom $ line "trust" u $ showTrustLevel Data.Default.def)
 	  where
 		trustlevels = unwords $ map showTrustLevel [Trusted .. DeadTrusted]
 
@@ -203,7 +221,7 @@ lcom = map (\l -> if "#" `isPrefixOf` l then l else '#' : l)
 {- If there's a parse error, returns a new version of the file,
  - with the problem lines noted. -}
 parseCfg :: Cfg -> String -> Either String Cfg
-parseCfg curcfg = go [] curcfg . lines
+parseCfg defcfg = go [] defcfg . lines
   where
 	go c cfg []
 		| null (mapMaybe fst c) = Right cfg

Logs/Trust.hs

@@ -19,6 +19,7 @@ module Logs.Trust (
 ) where
 
 import qualified Data.Map as M
+import Data.Default
 
 import Common.Annex
 import Types.TrustLevel
@@ -38,7 +39,7 @@ trustGet level = M.keys . M.filter (== level) <$> trustMap
 
 {- Returns the TrustLevel of a given repo UUID. -}
 lookupTrust :: UUID -> Annex TrustLevel
-lookupTrust u = (fromMaybe SemiTrusted . M.lookup u) <$> trustMap
+lookupTrust u = (fromMaybe def . M.lookup u) <$> trustMap
 
 {- Partitions a list of UUIDs to those matching a TrustLevel and not. -}
 trustPartition :: TrustLevel -> [UUID] -> Annex ([UUID], [UUID])

Types/StandardGroups.hs

@@ -9,6 +9,7 @@ module Types.StandardGroups where
 
 import Types.Remote (RemoteConfig)
 import Types.Group
+import Data.Default
 
 import qualified Data.Map as M
 import Data.Maybe

Types/TrustLevel.hs

@@ -14,6 +14,7 @@ module Types.TrustLevel (
 ) where
 
 import qualified Data.Map as M
+import Data.Default
 
 import Types.UUID
 
@@ -22,6 +23,9 @@ import Types.UUID
 data TrustLevel = Trusted | SemiTrusted | UnTrusted | DeadTrusted
 	deriving (Eq, Enum, Ord, Bounded)
 
+instance Default TrustLevel  where
+	def = SemiTrusted
+
 type TrustMap = M.Map UUID TrustLevel
 
 readTrustLevel :: String -> Maybe TrustLevel

debian/changelog

@@ -1,3 +1,10 @@
+git-annex (5.20141014) UNRELEASED; urgency=medium
+
+  * vicfg: Deleting configurations now resets to the default, where
+    before it has no effect.
+
+ -- Joey Hess <joeyh@debian.org>  Tue, 14 Oct 2014 14:09:24 -0400
+
 git-annex (5.20141013) unstable; urgency=medium
 
   * Adjust cabal file to support building w/o assistant on the hurd.

doc/todo/vicfg_comment_gotcha.mdwn

@@ -9,8 +9,12 @@ but that way lies madness. Also, it's not at all clear what the "default"
 should be in response to such an action. The default varies per type of
 configuration, and vicfg does't know about defaults.
 
+> [[fixed|done]]; this was a job for Data.Default!  --[[Joey]]
+
 Instead, I think it should detect when a setting provided in the input
 version of the file is not present in the output version, and plop the user
 back into the editor with an error, telling them that cannot be handled,
 and suggesting they instead change the value to the value they now want it
 to have.
+
+> Nah, too complicated.