move hashObject to HashObject library and generalize it to support all git object types

Git/CatFile.hs

@@ -21,6 +21,7 @@ import Common
 import Git
 import Git.Sha
 import Git.Command
+import Git.Types
 import qualified Utility.CoProcess as CoProcess
 
 type CatFileHandle = CoProcess.CoProcessHandle
@@ -52,7 +53,7 @@ catObject h object = CoProcess.query h send receive
 			case words header of
 				[sha, objtype, size]
 					| length sha == shaSize &&
-					  validobjtype objtype -> 
+					  isJust (readObjectType objtype) -> 
 						case reads size of
 							[(bytes, "")] -> readcontent bytes from
 							_ -> dne
@@ -67,8 +68,3 @@ catObject h object = CoProcess.query h send receive
 				error "missing newline from git cat-file"
 			return $ L.fromChunks [content]
 		dne = return L.empty
-		validobjtype t
-			| t == "blob" = True
-			| t == "commit" = True
-			| t == "tree" = True
-			| otherwise = False

Git/HashObject.hs

@@ -9,7 +9,9 @@ module Git.HashObject where
 
 import Common
 import Git
+import Git.Sha
 import Git.Command
+import Git.Types
 import qualified Utility.CoProcess as CoProcess
 
 type HashObjectHandle = CoProcess.CoProcessHandle
@@ -24,11 +26,23 @@ hashObjectStart = CoProcess.start "git" . toCommand . gitCommandLine
 hashObjectStop :: HashObjectHandle -> IO ()
 hashObjectStop = CoProcess.stop
 
-{- Injects a file into git, returning the shas of the objects. -}
+{- Injects a file into git, returning the Sha of the object. -}
 hashFile :: HashObjectHandle -> FilePath -> IO Sha
 hashFile h file = CoProcess.query h send receive
 	where
 		send to = do
 			fileEncoding to
 			hPutStrLn to file
-		receive from = Ref <$> hGetLine from
+		receive from = getSha "hash-object" $ hGetLine from
+
+{- Injects some content into git, returning its Sha. -}
+hashObject :: Repo -> ObjectType -> String -> IO Sha
+hashObject repo objtype content = getSha subcmd $ do
+	(h, s) <- pipeWriteRead (map Param params) content repo
+	length s `seq` do
+		forceSuccess h
+		reap -- XXX unsure why this is needed
+		return s
+	where
+		subcmd = "hash-object"
+		params = [subcmd, "-t", show objtype, "-w", "--stdin"]

Git/Types.hs

@@ -48,3 +48,18 @@ instance Show Ref where
 type Branch = Ref
 type Sha = Ref
 type Tag = Ref
+
+{- Types of objects that can be stored in git. -}
+data ObjectType = BlobObject | CommitObject | TreeObject
+
+instance Show ObjectType where
+	show BlobObject = "blob"
+	show CommitObject = "commit"
+	show TreeObject = "tree"
+
+readObjectType :: String -> Maybe ObjectType
+readObjectType "blob" = Just BlobObject
+readObjectType "commit" = Just CommitObject
+readObjectType "tree" = Just TreeObject
+readObjectType _ = Nothing
+

Git/UnionMerge.hs

@@ -10,7 +10,6 @@ module Git.UnionMerge (
 	merge_index
 ) where
 
-import System.Cmd.Utils
 import qualified Data.Text.Lazy as L
 import qualified Data.Text.Lazy.Encoding as L
 import qualified Data.Set as S
@@ -21,6 +20,8 @@ import Git.Sha
 import Git.CatFile
 import Git.Command
 import Git.UpdateIndex
+import Git.HashObject
+import Git.Types
 
 {- Performs a union merge between two branches, staging it in the index.
  - Any previously staged changes in the index will be lost.
@@ -72,7 +73,7 @@ mergeFile :: String -> FilePath -> CatFileHandle -> Repo -> IO (Maybe String)
 mergeFile info file h repo = case filter (/= nullSha) [Ref asha, Ref bsha] of
 	[] -> return Nothing
 	(sha:[]) -> use sha
-	shas -> use =<< either return (hashObject repo . unlines) =<<
+	shas -> use =<< either return (hashObject repo BlobObject . unlines) =<<
 		calcMerge . zip shas <$> mapM getcontents shas
 	where
 		[_colonmode, _bmode, asha, bsha, _status] = words info
@@ -80,18 +81,6 @@ mergeFile info file h repo = case filter (/= nullSha) [Ref asha, Ref bsha] of
 			L.decodeUtf8 <$> catObject h s
 		use sha = return $ Just $ update_index_line sha file
 
-{- Injects some content into git, returning its Sha. -}
-hashObject :: Repo -> String -> IO Sha
-hashObject repo content = getSha subcmd $ do
-	(h, s) <- pipeWriteRead (map Param params) content repo
-	length s `seq` do
-		forceSuccess h
-		reap -- XXX unsure why this is needed
-		return s
-	where
-		subcmd = "hash-object"
-		params = [subcmd, "-w", "--stdin"]
-
 {- Calculates a union merge between a list of refs, with contents.
  -
  - When possible, reuses the content of an existing ref, rather than