improve type signatures with a Ref newtype

In git, a Ref can be a Sha, or a Branch, or a Tag. I added type aliases for
those. Note that this does not prevent mixing up of eg, refs and branches
at the type level. Since git really doesn't care, except rare cases like
git update-ref, or git tag -d, that seems ok for now.

There's also a tree-ish, but let's just use Ref for it. A given Sha or Ref
may or may not be a tree-ish, depending on the object type, so there seems
no point in trying to represent it at the type level.
This commit is contained in:
Joey Hess 2011-11-16 02:23:34 -04:00
parent 272a67921c
commit 9290095fc2
10 changed files with 86 additions and 71 deletions

View file

@ -37,14 +37,14 @@ catFileStop (pid, from, to) = do
forceSuccess pid
{- Reads a file from a specified branch. -}
catFile :: CatFileHandle -> String -> FilePath -> IO L.ByteString
catFile h branch file = catObject h (branch ++ ":" ++ file)
catFile :: CatFileHandle -> Branch -> FilePath -> IO L.ByteString
catFile h branch file = catObject h $ Ref $ show branch ++ ":" ++ file
{- Uses a running git cat-file read the content of an object.
- Objects that do not exist will have "" returned. -}
catObject :: CatFileHandle -> String -> IO L.ByteString
catObject :: CatFileHandle -> Ref -> IO L.ByteString
catObject (_, from, to) object = do
hPutStrLn to object
hPutStrLn to $ show object
hFlush to
header <- hGetLine from
case words header of
@ -53,7 +53,7 @@ catObject (_, from, to) object = do
validobjtype objtype -> handle size
| otherwise -> empty
_
| header == object ++ " missing" -> empty
| header == show object ++ " missing" -> empty
| otherwise -> error $ "unknown response from git cat-file " ++ header
where
handle size = case reads size of