split out Git/Ref.hs

Git/Ref.hs

@@ -0,0 +1,47 @@
+{- git ref stuff
+ -
+ - Copyright 2011 Joey Hess <joey@kitenet.net>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Git.Ref where
+
+import qualified Data.ByteString.Lazy.Char8 as L
+
+import Common
+import Git
+
+{- Converts a fully qualified git ref into a user-visible version. -}
+describe :: Ref -> String
+describe = remove "refs/heads/" . remove "refs/remotes/" . show
+	where
+		remove prefix s
+			| prefix `isPrefixOf` s = drop (length prefix) s
+			| otherwise = s
+
+{- Checks if a ref exists. -}
+exists :: Ref -> Repo -> IO Bool
+exists ref = runBool "show-ref" 
+	[Param "--verify", Param "-q", Param $ show ref]
+
+{- Get the sha of a fully qualified git ref, if it exists. -}
+sha :: Branch -> Repo -> IO (Maybe Sha)
+sha branch repo = process . L.unpack <$> showref repo
+	where
+		showref = pipeRead [Param "show-ref",
+			Param "--hash", -- get the hash
+			Param $ show branch]
+		process [] = Nothing
+		process s = Just $ Ref $ firstLine s
+
+{- List of (refs, branches) matching a given ref spec.
+ - Duplicate refs are filtered out. -}
+matching :: Ref -> Repo -> IO [(Git.Ref, Git.Branch)]
+matching ref repo = do
+	r <- Git.pipeRead [Param "show-ref", Param $ show ref] repo
+	return $ nubBy uref $ map (gen . words . L.unpack) (L.lines r)
+	where
+		gen l = (Git.Ref $ head l, Git.Ref $ last l)
+		uref (a, _) (b, _) = a == b
+