add git annex view command

(And a vpop command, which is still a bit buggy.)

Still need to do vadd and vrm, though this also adds their documentation.

Currently not very happy with the view log data serialization. I had to
lose the TDFA regexps temporarily, so I can have Read/Show instances of
View. I expect the view log format will change in some incompatable way
later, probably adding last known refs for the parent branch to View
or something like that.

Anyway, it basically works, although it's a bit slow looking up the
metadata. The actual git branch construction is about as fast as it can be
using the current git plumbing.

This commit was sponsored by Peter Hogg.

1 files changed, 46 insertions, 0 deletions

diff --git a/Annex/Index.hs b/Annex/Index.hs
new file mode 100644
index 000000000..a1b2442fc
--- /dev/null
+++ b/Annex/Index.hs
@@ -0,0 +1,46 @@
+{- Using other git index files
+ -
+ - Copyright 2014 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+{-# LANGUAGE CPP #-}
+
+module Annex.Index (
+	withIndexFile,
+) where
+
+import qualified Control.Exception as E
+
+import Common.Annex
+import Git.Types
+import qualified Annex
+import Utility.Env
+import Annex.Exception
+
+{- Runs an action using a different git index file. -}
+withIndexFile :: FilePath -> Annex a -> Annex a
+withIndexFile f a = do
+	g <- gitRepo
+#ifdef __ANDROID__
+	{- This should not be necessary on Android, but there is some
+	 - weird getEnvironment breakage. See
+	 - https://github.com/neurocyte/ghc-android/issues/7
+	 - Use getEnv to get some key environment variables that
+	 - git expects to have. -}
+	let keyenv = words "USER PATH GIT_EXEC_PATH HOSTNAME HOME"
+	let getEnvPair k = maybe Nothing (\v -> Just (k, v)) <$> getEnv k
+	e <- liftIO $ catMaybes <$> forM keyenv getEnvPair
+	let e' = ("GIT_INDEX_FILE", f):e
+#else
+	e <- liftIO getEnvironment
+	let e' = addEntry "GIT_INDEX_FILE" f e
+#endif
+	let g' = g { gitEnv = Just e' }
+
+	r <- tryAnnex $ do
+		Annex.changeState $ \s -> s { Annex.repo = g' }
+		a
+	Annex.changeState $ \s -> s { Annex.repo = (Annex.repo s) { gitEnv = gitEnv g} }
+	either E.throw return r