add directory to views for files that lack specified metadata

* view: New field?=glob and ?tag syntax that includes a directory "_"
  in the view for files that do not have the specified metadata set.
* Added annex.viewunsetdirectory git config to change the name of the
  "_" directory in a view.

When in a view using the new syntax, old git-annex will fail to parse the
view log. It errors with "Not in a view.", which is not ideal. But that
only affects view commands.

annex.viewunsetdirectory is included in the View for a couple of reasons.
One is to avoid needing to warn the user that it should not be changed when
in a view, since that would confuse git-annex. Another reason is that it
helped with plumbing the value through to some pure functions.

annex.viewunsetdirectory is actually mangled the same as any other view
directory. So if it's configured to something like "N/A", there won't be
multiple levels of directories, which would also confuse git-annex.

Sponsored-By: Jack Hill on Patreon

Annex/View.hs

@@ -1,6 +1,6 @@
 {- metadata based branch views
  -
- - Copyright 2014 Joey Hess <id@joeyh.name>
+ - Copyright 2014-2023 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU AGPL version 3 or higher.
  -}
@@ -56,19 +56,23 @@ viewTooLarge view = visibleViewSize view > 5
 visibleViewSize :: View -> Int
 visibleViewSize = length . filter viewVisible . viewComponents
 
-{- Parses field=value, field!=value, tag, and !tag
+{- Parses field=value, field!=value, field?=value, tag, !tag, and ?tag
  -
  - Note that the field may not be a legal metadata field name,
  - but it's let through anyway.
  - This is useful when matching on directory names with spaces,
  - which are not legal MetaFields.
  -}
-parseViewParam :: String -> (MetaField, ViewFilter)
-parseViewParam s = case separate (== '=') s of
+parseViewParam :: ViewUnset -> String -> (MetaField, ViewFilter)
+parseViewParam vu s = case separate (== '=') s of
 	('!':tag, []) | not (null tag) ->
 		( tagMetaField
 		, mkExcludeValues tag
 		)
+	('?':tag, []) | not (null tag) ->
+		( tagMetaField
+		, mkFilterOrUnsetValues tag
+		)
 	(tag, []) ->
 		( tagMetaField
 		, mkFilterValues tag
@@ -78,15 +82,22 @@ parseViewParam s = case separate (== '=') s of
 			( mkMetaFieldUnchecked (T.pack (beginning field))
 			, mkExcludeValues wanted
 			)
+		| end field == "?" ->
+			( mkMetaFieldUnchecked (T.pack (beginning field))
+			, mkFilterOrUnsetValues wanted
+			)
 		| otherwise ->
 			( mkMetaFieldUnchecked (T.pack field)
 			, mkFilterValues wanted
 			)
   where
+	mkExcludeValues = ExcludeValues . S.singleton . toMetaValue . encodeBS
 	mkFilterValues v
 		| any (`elem` v) ['*', '?'] = FilterGlob v
 		| otherwise = FilterValues $ S.singleton $ toMetaValue $ encodeBS v
-	mkExcludeValues = ExcludeValues . S.singleton . toMetaValue . encodeBS
+	mkFilterOrUnsetValues v
+		| any (`elem` v) ['*', '?'] = FilterGlobOrUnset v vu
+		| otherwise = FilterValuesOrUnset (S.singleton $ toMetaValue $ encodeBS v) vu
 
 data ViewChange = Unchanged | Narrowing | Widening
 	deriving (Ord, Eq, Show)
@@ -136,18 +147,8 @@ filterView v vs = v { viewComponents = viewComponents f' ++ viewComponents v}
 	toinvisible c = c { viewVisible = False }
 
 {- Combine old and new ViewFilters, yielding a result that matches
- - either old+new, or only new.
- -
- - If we have FilterValues and change to a FilterGlob,
- - it's always a widening change, because the glob could match other
- - values. OTOH, going the other way, it's a Narrowing change if the old
- - glob matches all the new FilterValues.
- -
- - With two globs, the old one is discarded, and the new one is used.
- - We can tell if that's a narrowing change by checking if the old
- - glob matches the new glob. For example, "*" matches "foo*",
- - so that's narrowing. While "f?o" does not match "f??", so that's
- - widening.
+ - either old+new, or only new. Which depends on the types of things
+ - being combined.
  -}
 combineViewFilter :: ViewFilter -> ViewFilter -> (ViewFilter, ViewChange)
 combineViewFilter old@(FilterValues olds) (FilterValues news)
@@ -160,19 +161,74 @@ combineViewFilter old@(ExcludeValues olds) (ExcludeValues news)
 	| otherwise = (combined, Narrowing)
   where
 	combined = ExcludeValues (S.union olds news)
+{- If we have FilterValues and change to a FilterGlob,
+ - it's always a widening change, because the glob could match other
+ - values. OTOH, going the other way, it's a Narrowing change if the old
+ - glob matches all the new FilterValues. -}
 combineViewFilter (FilterValues _) newglob@(FilterGlob _) =
 	(newglob, Widening)
 combineViewFilter (FilterGlob oldglob) new@(FilterValues s)
 	| all (matchGlob (compileGlob oldglob CaseInsensative (GlobFilePath False)) . decodeBS . fromMetaValue) (S.toList s) = (new, Narrowing)
 	| otherwise = (new, Widening)
+{- With two globs, the old one is discarded, and the new one is used.
+ - We can tell if that's a narrowing change by checking if the old
+ - glob matches the new glob. For example, "*" matches "foo*",
+ - so that's narrowing. While "f?o" does not match "f??", so that's
+ - widening. -}
 combineViewFilter (FilterGlob old) newglob@(FilterGlob new)
 	| old == new = (newglob, Unchanged)
 	| matchGlob (compileGlob old CaseInsensative (GlobFilePath False)) new = (newglob, Narrowing)
 	| otherwise = (newglob, Widening)
+{- Combining FilterValuesOrUnset and FilterGlobOrUnset with FilterValues
+ - and FilterGlob maintains the OrUnset if the second parameter has it,
+ - and is otherwise the same as combining without OrUnset, except that
+ - eliminating the OrUnset can be narrowing, and adding it can be widening. -}
+combineViewFilter old@(FilterValuesOrUnset olds _) (FilterValuesOrUnset news newvu)
+	| combined == old = (combined, Unchanged)
+	| otherwise = (combined, Widening)
+  where
+	combined = FilterValuesOrUnset (S.union olds news) newvu
+combineViewFilter (FilterValues olds) (FilterValuesOrUnset news vu) =
+	(combined, Widening)
+  where
+	combined = FilterValuesOrUnset (S.union olds news) vu
+combineViewFilter old@(FilterValuesOrUnset olds _) (FilterValues news)
+	| combined == old = (combined, Narrowing)
+	| otherwise = (combined, Widening)
+  where
+	combined = FilterValues (S.union olds news)
+combineViewFilter (FilterValuesOrUnset _ _) newglob@(FilterGlob _) =
+	(newglob, Widening)
+combineViewFilter (FilterGlob _) new@(FilterValuesOrUnset _ _) =
+	(new, Widening)
+combineViewFilter (FilterValues _) newglob@(FilterGlobOrUnset _ _) =
+	(newglob, Widening)
+combineViewFilter (FilterValuesOrUnset _ _) newglob@(FilterGlobOrUnset _ _) =
+	(newglob, Widening)
+combineViewFilter (FilterGlobOrUnset oldglob _) new@(FilterValues _) =
+	combineViewFilter (FilterGlob oldglob) new
+combineViewFilter (FilterGlobOrUnset oldglob _) new@(FilterValuesOrUnset _ _) =
+	let (_, viewchange) = combineViewFilter (FilterGlob oldglob) new
+	in (new, viewchange)
+combineViewFilter (FilterGlobOrUnset old _) newglob@(FilterGlobOrUnset new _)
+	| old == new = (newglob, Unchanged)
+	| matchGlob (compileGlob old CaseInsensative (GlobFilePath False)) new = (newglob, Narrowing)
+	| otherwise = (newglob, Widening)
+combineViewFilter (FilterGlob _) newglob@(FilterGlobOrUnset _ _) =
+	(newglob, Widening)
+combineViewFilter (FilterGlobOrUnset _ _) newglob@(FilterGlob _) =
+	(newglob, Narrowing)
+{- There is not a way to filter a value and also apply an exclude. So:
+ - When adding an exclude to a filter, use only the exclude.
+ - When adding a filter to an exclude, use only the filter. -}
 combineViewFilter (FilterGlob _) new@(ExcludeValues _) = (new, Narrowing)
 combineViewFilter (ExcludeValues _) new@(FilterGlob _) = (new, Widening)
 combineViewFilter (FilterValues _) new@(ExcludeValues _) = (new, Narrowing)
 combineViewFilter (ExcludeValues _) new@(FilterValues _) = (new, Widening)
+combineViewFilter (FilterValuesOrUnset _ _) new@(ExcludeValues _) = (new, Narrowing)
+combineViewFilter (ExcludeValues _) new@(FilterValuesOrUnset _ _) = (new, Widening)
+combineViewFilter (FilterGlobOrUnset _ _) new@(ExcludeValues _) = (new, Narrowing)
+combineViewFilter (ExcludeValues _) new@(FilterGlobOrUnset _ _) = (new, Widening)
 
 {- Generates views for a file from a branch, based on its metadata
  - and the filename used in the branch.
@@ -196,7 +252,7 @@ viewedFiles view =
 			then []
 			else 
 				let paths = pathProduct $
-					map (map toViewPath) (visible matches)
+					map (map toviewpath) (visible matches)
 				in if null paths
 					then [mkviewedfile file]
 					else map (</> mkviewedfile file) paths
@@ -204,28 +260,40 @@ viewedFiles view =
 	visible = map (fromJust . snd) .
 		filter (viewVisible . fst) .
 		zip (viewComponents view)
+	
+	toviewpath (MatchingMetaValue v) = toViewPath v
+	toviewpath (MatchingUnset v) = toViewPath (toMetaValue (encodeBS v))
+
+data MatchingValue = MatchingMetaValue MetaValue | MatchingUnset String
 
 {- Checks if metadata matches a ViewComponent filter, and if so
  - returns the value, or values that match. Self-memoizing on ViewComponent. -}
-viewComponentMatcher :: ViewComponent -> (MetaData -> Maybe [MetaValue])
+viewComponentMatcher :: ViewComponent -> (MetaData -> Maybe [MatchingValue])
 viewComponentMatcher viewcomponent = \metadata -> 
-	matcher (currentMetaDataValues metafield metadata)
+	matcher Nothing (viewFilter viewcomponent)
+		(currentMetaDataValues metafield metadata)
   where
 	metafield = viewField viewcomponent
-	matcher = case viewFilter viewcomponent of
-		FilterValues s -> \values -> setmatches $
-			S.intersection s values
-		FilterGlob glob ->
-			let cglob = compileGlob glob CaseInsensative (GlobFilePath False)
-			in \values -> setmatches $
-				S.filter (matchGlob cglob . decodeBS . fromMetaValue) values
-		ExcludeValues excludes -> \values -> 
+	matcher matchunset (FilterValues s) = 
+		\values -> setmatches matchunset $ S.intersection s values
+	matcher matchunset (FilterGlob glob) =
+		let cglob = compileGlob glob CaseInsensative (GlobFilePath False)
+		in \values -> setmatches matchunset $
+			S.filter (matchGlob cglob . decodeBS . fromMetaValue) values
+	matcher _ (ExcludeValues excludes) = 
+		\values -> 
 			if S.null (S.intersection values excludes)
 				then Just []
 				else Nothing
-	setmatches s
-		| S.null s = Nothing
-		| otherwise = Just (S.toList s)
+	matcher _ (FilterValuesOrUnset s (ViewUnset u)) =
+		matcher (Just [MatchingUnset u]) (FilterValues s)
+	matcher _ (FilterGlobOrUnset glob (ViewUnset u)) =
+		matcher (Just [MatchingUnset u]) (FilterGlob glob)
+
+	setmatches matchunset s
+		| S.null s = matchunset 
+		| otherwise = Just $
+			map MatchingMetaValue (S.toList s)
 
 -- This is '∕', a unicode character that displays the same as '/' but is
 -- not it. It is encoded using the filesystem encoding, which allows it
@@ -282,14 +350,25 @@ pathProduct (l:ls) = foldl combinel l ls
  - Derived metadata is excluded.
  -}
 fromView :: View -> ViewedFile -> MetaData
-fromView view f = MetaData $
-	M.fromList (zip fields values) `M.difference` derived
+fromView view f = MetaData $ m `M.difference` derived
   where
+	m = M.fromList $ map convfield $
+		filter (not . isviewunset) (zip visible values)
 	visible = filter viewVisible (viewComponents view)
-	fields = map viewField visible
 	paths = splitDirectories (dropFileName f)
 	values = map (S.singleton . fromViewPath) paths
 	MetaData derived = getViewedFileMetaData f
+	convfield (vc, v) = (viewField vc, v)
+
+	-- When a directory is the one used to hold files that don't
+	-- have the metadata set, don't include it in the MetaData.
+	isviewunset (vc, v) = case viewFilter vc of
+		FilterValues {} -> False
+		FilterGlob {} -> False
+		ExcludeValues {} -> False
+		FilterValuesOrUnset _ (ViewUnset vu) -> isviewunset' vu v
+		FilterGlobOrUnset _ (ViewUnset vu) -> isviewunset' vu v
+	isviewunset' vu v = S.member (fromViewPath vu) v
 
 {- Constructing a view that will match arbitrary metadata, and applying
  - it to a file yields a set of ViewedFile which all contain the same

CHANGELOG

@@ -2,6 +2,10 @@ git-annex (10.20230127) UNRELEASED; urgency=medium
 
   * S3: Support a region= configuration useful for some non-Amazon S3
     implementations. This feature needs git-annex to be built with aws-0.24.
+  * view: New field?=glob and ?tag syntax that includes a directory "_"
+    in the view for files that do not have the specified metadata set.
+  * Added annex.viewunsetdirectory git config to change the name of the
+    "_" directory in a view.
 
  -- Joey Hess <id@joeyh.name>  Mon, 06 Feb 2023 13:39:18 -0400
 

Command/VAdd.hs

@@ -8,6 +8,7 @@
 module Command.VAdd where
 
 import Command
+import qualified Annex
 import Annex.View
 import Command.View (checkoutViewBranch)
 
@@ -24,8 +25,9 @@ seek = withWords (commandAction . start)
 start :: [String] -> CommandStart
 start params = starting "vadd" (ActionItemOther Nothing) (SeekInput params) $ 
 	withCurrentView $ \view -> do
+		vu <- annexViewUnsetDirectory <$> Annex.getGitConfig
 		let (view', change) = refineView view $
-			map parseViewParam $ reverse params
+			map (parseViewParam vu) (reverse params)
 		case change of
 			Unchanged -> do
 				showNote "unchanged"

Command/VFilter.hs

@@ -8,6 +8,7 @@
 module Command.VFilter where
 
 import Command
+import qualified Annex
 import Annex.View
 import Command.View (paramView, checkoutViewBranch)
 
@@ -22,8 +23,9 @@ seek = withWords (commandAction . start)
 start :: [String] -> CommandStart
 start params = starting "vfilter" (ActionItemOther Nothing) (SeekInput params) $
 	withCurrentView $ \view -> do
+		vu <- annexViewUnsetDirectory <$> Annex.getGitConfig
 		let view' = filterView view $
-			map parseViewParam $ reverse params
+			map (parseViewParam vu) (reverse params)
 		next $ if visibleViewSize view' > visibleViewSize view
 			then giveup "That would add an additional level of directory structure to the view, rather than filtering it. If you want to do that, use vadd instead of vfilter."
 			else checkoutViewBranch view' narrowView

Command/View.hs

@@ -8,6 +8,7 @@
 module Command.View where
 
 import Command
+import qualified Annex
 import qualified Git
 import qualified Git.Command
 import qualified Git.Ref
@@ -83,8 +84,10 @@ mkView :: [String] -> Annex View
 mkView ps = go =<< inRepo Git.Branch.current
   where
 	go Nothing = giveup "not on any branch!"
-	go (Just b) = return $ fst $ refineView (View b []) $
-		map parseViewParam $ reverse ps
+	go (Just b) = do
+		vu <- annexViewUnsetDirectory <$> Annex.getGitConfig
+		return $ fst $ refineView (View b []) $
+			map (parseViewParam vu) (reverse ps)
 
 checkoutViewBranch :: View -> (View -> Annex Git.Branch) -> CommandCleanup
 checkoutViewBranch view mkbranch = do

Logs/View.hs

@@ -86,6 +86,8 @@ branchView view
 	branchvals (FilterValues set) = '=' : branchset set
 	branchvals (FilterGlob glob) = '=' : forcelegal glob
 	branchvals (ExcludeValues set) = "!=" ++ branchset set
+	branchvals (FilterValuesOrUnset set _) = '=' : branchset set
+	branchvals (FilterGlobOrUnset glob _) = '=' : forcelegal glob
 	branchset = intercalate ","
 		. map (forcelegal . decodeBS . fromMetaValue)
 		. S.toList

Types/GitConfig.hs

@@ -43,6 +43,7 @@ import Types.Difference
 import Types.RefSpec
 import Types.RepoVersion
 import Types.StallDetection
+import Types.View
 import Config.DynamicConfig
 import Utility.HumanTime
 import Utility.Gpg (GpgCmd, mkGpgCmd)
@@ -145,6 +146,7 @@ data GitConfig = GitConfig
 	, mergeDirectoryRenames :: Maybe String
 	, annexPrivateRepos :: S.Set UUID
 	, annexAdviceNoSshCaching :: Bool
+	, annexViewUnsetDirectory :: ViewUnset
 	}
 
 extractGitConfig :: ConfigSource -> Git.Repo -> GitConfig
@@ -266,6 +268,8 @@ extractGitConfig configsource r = GitConfig
 		  in mapMaybe get (M.toList (Git.config r))
 		]
 	, annexAdviceNoSshCaching = getbool (annexConfig "advicenosshcaching") True
+	, annexViewUnsetDirectory = ViewUnset $ fromMaybe "_" $
+		getmaybe (annexConfig "viewunsetdirectory")
 	}
   where
 	getbool k d = fromMaybe d $ getmaybebool k

Types/View.hs

@@ -1,6 +1,6 @@
 {- types for metadata based branch views
  -
- - Copyright 2014 Joey Hess <id@joeyh.name>
+ - Copyright 2014-2023 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU AGPL version 3 or higher.
  -}
@@ -9,9 +9,9 @@
 
 module Types.View where
 
-import Annex.Common
 import Types.MetaData
 import Utility.QuickCheck
+import Utility.Monad
 import qualified Git
 
 import qualified Data.Set as S
@@ -42,6 +42,11 @@ data ViewFilter
 	= FilterValues (S.Set MetaValue)
 	| FilterGlob String
 	| ExcludeValues (S.Set MetaValue)
+	| FilterValuesOrUnset (S.Set MetaValue) ViewUnset
+	| FilterGlobOrUnset String ViewUnset
+	deriving (Eq, Read, Show)
+
+newtype ViewUnset = ViewUnset String
 	deriving (Eq, Read, Show)
 
 instance Arbitrary ViewFilter where
@@ -60,3 +65,5 @@ multiValue :: ViewFilter -> Bool
 multiValue (FilterValues s) = S.size s > 1
 multiValue (FilterGlob _) = True
 multiValue (ExcludeValues _) = False
+multiValue (FilterValuesOrUnset _ _) = True
+multiValue (FilterGlobOrUnset _ _) = True

doc/git-annex-vadd.mdwn

@@ -4,7 +4,7 @@ git-annex vadd - add subdirs to current view
 
 # SYNOPSIS
 
-git annex vadd `[field=glob ...] [field=value ...] [tag ...]`
+git annex vadd `[field=glob ...] [field=value ...] [tag ...] [?tag ...] [field?=glob]`
 
 # DESCRIPTION
 

doc/git-annex-vfilter.mdwn

@@ -4,7 +4,7 @@ git-annex vfilter - filter current view
 
 # SYNOPSIS
 
-git annex vfilter `[tag ...] [field=value ...] [!tag ...] [field!=value ...]`
+git annex vfilter `[tag ...] [field=value ...] [?tag ...] [field?=glob] [!tag ...] [field!=value ...]`
 
 # DESCRIPTION
 

doc/git-annex-view.mdwn

@@ -4,7 +4,7 @@ git-annex view - enter a view branch
 
 # SYNOPSIS
 
-git annex view `[tag ...] [field=value ...] [field=glob ...] [!tag ...] [field!=value ...]`
+git annex view `[tag ...] [field=value ...] [field=glob ...] [?tag ...] [field?=glob] [!tag ...] [field!=value ...]`
 
 # DESCRIPTION
 
@@ -21,12 +21,12 @@ Once within such a view, you can make additional directories, and
 copy or move files into them. When you commit, the metadata will
 be updated to correspond to your changes. Deleting files and committing
 also updates the metadata.
-  
-There are fields corresponding to the path to the file. So a file
-"foo/bar/baz/file" has fields "/=foo", "foo/=bar", and "foo/bar/=baz".
-These location fields can be used the same as other metadata to construct
-the view.
-  
+
+As well as the usual metadata, there are fields available corresponding
+to the path to the file. So a file "foo/bar/baz/file" has fields "/=foo",
+"foo/=bar", and "foo/bar/=baz". These location fields can be used the
+same as other metadata to construct the view.
+
 For example, `/=foo` will only include files from the foo
 directory in the view, while `foo/=*` will preserve the
 subdirectories of the foo directory in the view.
@@ -34,6 +34,16 @@ subdirectories of the foo directory in the view.
 To enter a view containing only files that lack a given metadata
 value or tag, specify field!=value or !tag. (Globs cannot be used here.)
 
+`field?=*` is like `field=*` but adds an additional directory named `_` (by
+default) that contains files that do not have the field set to any value.
+Similarly, `?tag` adds an additional directory named `_` that contains
+files that do not have any tags set. Moving files from the `_` directory to
+another directory and committing will set the metadata. And moving files
+into the `_` directory and committing will unset the metadata. 
+
+The name of the `_` directory can be changed using the annex.viewunsetdirectory
+git config.
+
 # OPTIONS
 
 * The [[git-annex-common-options]](1) can be used.

doc/git-annex.mdwn

@@ -506,7 +506,7 @@ content from the key-value store.
 
   See [[git-annex-metadata]](1) for details.
 
-* `view [tag ...] [field=value ...] [field=glob ...] [!tag ...] [field!=value ...]`
+* `view [tag ...] [field=value ...] [field=glob ...] [?tag ...] [field?=glob] [!tag ...] [field!=value ...]`
 
   Uses metadata to build a view branch of the files in the current branch,
   and checks out the view branch. Only files in the current branch whose
@@ -1177,6 +1177,12 @@ repository, using [[git-annex-config]]. See its man page for a list.)
   To configure the behavior in all clones of the repository,
   this can be set in [[git-annex-config]](1).
 
+* `annex.viewunsetdirectory`
+
+  This configures the name of a directory that is used in a view to contain
+  files that do not have metadata set. The default name for the directory 
+  is `"_"`. See [[git-annex-view]](1) for details.
+
 * `annex.debug`
 
   Set to true to enable debug logging by default.

doc/todo/Adding_unmatched_files_to_a_view.mdwn

@@ -11,3 +11,5 @@ What do you think? Is something like `git annex view --show-unmatched '???'` wor
 Thanks again for git-annex, I love it, it's so versatile... 💛
 
 Yann
+
+> [[fixed|done]] --[[Joey]]

doc/todo/Adding_unmatched_files_to_a_view/comment_2_271f37d6c3e0f61324f9f50cb9cf24c7._comment

@@ -0,0 +1,8 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 2"""
+ date="2023-02-07T20:19:29Z"
+ content="""
+Implemented this! Using the "field?=*" syntax described.
+With the directory configurable by annex.viewunsetdirectory
+"""]]