--branch, stage 1

Added --branch option to copy, drop, fsck, get, metadata, mirror, move, and
whereis commands. This option makes git-annex operate on files that are
included in a specified branch (or other treeish).

The names of the files from the branch that are being operated on are not
displayed yet; only the keys. Displaying the filenames will need changes
to every affected command.

Also, note that --branch can be specified repeatedly. This is not really
documented, but seemed worth supporting, especially since we may later want
the ability to operate on all branches matching a refspec. However, when
operating on two branches that contain the same key, that key will be
operated on twice.

CmdLine/GitAnnex/Options.hs

@@ -141,6 +141,7 @@ data KeyOptions
 	| WantUnusedKeys
 	| WantSpecificKey Key
 	| WantIncompleteKeys
+	| WantBranchKeys [Branch]
 
 parseKeyOptions :: Bool -> Parser KeyOptions
 parseKeyOptions allowincomplete = if allowincomplete
@@ -152,6 +153,10 @@ parseKeyOptions allowincomplete = if allowincomplete
 	else base
   where
 	base = parseAllOption
+		<|> WantBranchKeys <$> many (option (str >>= pure . Ref)
+			( long "branch" <> metavar paramRef
+			<> help "operate on files in the specified branch or treeish"
+			))
 		<|> flag' WantUnusedKeys
 			( long "unused" <> short 'U'
 			<> help "operate on files found by last run of git-annex unused"

CmdLine/Seek.hs

@@ -154,7 +154,7 @@ withNothing :: CommandStart -> CmdParams -> CommandSeek
 withNothing a [] = seekActions $ return [a]
 withNothing _ _ = error "This command takes no parameters."
 
-{- Handles the --all, --unused, --key, and --incomplete options,
+{- Handles the --all, --branch, --unused, --key, and --incomplete options,
  - which specify particular keys to run an action on.
  -
  - In a bare repo, --all is the default.
@@ -162,34 +162,49 @@ withNothing _ _ = error "This command takes no parameters."
  - Otherwise falls back to a regular CommandSeek action on
  - whatever params were passed. -}
 withKeyOptions :: Maybe KeyOptions -> Bool -> (Key -> CommandStart) -> (CmdParams -> CommandSeek) -> CmdParams -> CommandSeek
-withKeyOptions ko auto keyaction = withKeyOptions' ko auto $ \getkeys -> do
-	matcher <- Limit.getMatcher
-	seekActions $ map (process matcher) <$> getkeys
+withKeyOptions ko auto keyaction = withKeyOptions' ko auto mkkeyaction
   where
+	mkkeyaction = do
+		matcher <- Limit.getMatcher
+		return $ \getkeys ->
+			seekActions $ map (process matcher) <$> getkeys
 	process matcher k = ifM (matcher $ MatchingKey k)
 		( keyaction k
 		, return Nothing
 		)
 
-withKeyOptions' :: Maybe KeyOptions -> Bool -> (Annex [Key] -> Annex ()) -> (CmdParams -> CommandSeek) -> CmdParams -> CommandSeek
-withKeyOptions' ko auto keyaction fallbackaction params = do
+withKeyOptions' :: Maybe KeyOptions -> Bool -> Annex (Annex [Key] -> Annex ()) -> (CmdParams -> CommandSeek) -> CmdParams -> CommandSeek
+withKeyOptions' ko auto mkkeyaction fallbackaction params = do
 	bare <- fromRepo Git.repoIsLocalBare
 	when (auto && bare) $
 		error "Cannot use --auto in a bare repository"
 	case (null params, ko) of
 		(True, Nothing)
-			| bare -> go auto loggedKeys
+			| bare -> noauto $ runkeyaction loggedKeys
 			| otherwise -> fallbackaction params
 		(False, Nothing) -> fallbackaction params
-		(True, Just WantAllKeys) -> go auto loggedKeys
-		(True, Just WantUnusedKeys) -> go auto unusedKeys'
-		(True, Just (WantSpecificKey k)) -> go auto $ return [k]
-		(True, Just WantIncompleteKeys) -> go auto incompletekeys
-		(False, Just _) -> error "Can only specify one of file names, --all, --unused, --key, or --incomplete"
+		(True, Just WantAllKeys) -> noauto $ runkeyaction loggedKeys
+		(True, Just WantUnusedKeys) -> noauto $ runkeyaction unusedKeys'
+		(True, Just (WantSpecificKey k)) -> noauto $ runkeyaction (return [k])
+		(True, Just WantIncompleteKeys) -> noauto $ runkeyaction incompletekeys
+		(True, Just (WantBranchKeys bs)) -> noauto $ runbranchkeys bs
+		(False, Just _) -> error "Can only specify one of file names, --all, --branch, --unused, --key, or --incomplete"
   where
-	go True _ = error "Cannot use --auto with --all or --unused or --key or --incomplete"
-	go False getkeys = keyaction getkeys
+	noauto a
+		| auto = error "Cannot use --auto with --all or --branch or --unused or --key or --incomplete"
+		| otherwise = a
 	incompletekeys = staleKeysPrune gitAnnexTmpObjectDir True
+	runkeyaction ks = do
+		keyaction <- mkkeyaction
+		keyaction ks
+	runbranchkeys bs = do
+		keyaction <- mkkeyaction
+		forM_ bs $ \b -> do
+			(l, cleanup) <- inRepo $ LsTree.lsTree b
+			forM_ l $ \i ->
+				maybe noop (\k -> keyaction (return [k]))
+					=<< catKey (LsTree.sha i)
+			liftIO $ void cleanup
 
 prepFiltered :: (FilePath -> CommandStart) -> Annex [FilePath] -> Annex [CommandStart]
 prepFiltered a fs = do
@@ -200,9 +215,7 @@ prepFiltered a fs = do
 		( a f , return Nothing )
 
 seekActions :: Annex [CommandStart] -> Annex ()
-seekActions gen = do
-	as <- gen
-	mapM_ commandAction as
+seekActions gen = mapM_ commandAction =<< gen
 
 seekHelper :: ([FilePath] -> Git.Repo -> IO ([FilePath], IO Bool)) -> [FilePath] -> Annex [FilePath]
 seekHelper a params = do