git-annex/Git/LsTree.hs
Joey Hess 9290095fc2 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.
2011-11-16 02:41:46 -04:00

50 lines
1.2 KiB
Haskell

{- git ls-tree interface
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Git.LsTree (
TreeItem(..),
lsTree,
parseLsTree
) where
import Numeric
import Control.Applicative
import System.Posix.Types
import qualified Data.ByteString.Lazy.Char8 as L
import Git
import Utility.SafeCommand
data TreeItem = TreeItem
{ mode :: FileMode
, typeobj :: String
, sha :: String
, file :: FilePath
} deriving Show
{- Lists the contents of a Ref -}
lsTree :: Ref -> Repo -> IO [TreeItem]
lsTree t repo = map parseLsTree <$>
pipeNullSplitB [Params "ls-tree --full-tree -z -r --", File $ show t] repo
{- Parses a line of ls-tree output.
- (The --long format is not currently supported.) -}
parseLsTree :: L.ByteString -> TreeItem
parseLsTree l = TreeItem
{ mode = fst $ head $ readOct $ L.unpack m
, typeobj = L.unpack t
, sha = L.unpack s
, file = decodeGitFile $ L.unpack f
}
where
-- l = <mode> SP <type> SP <sha> TAB <file>
-- All fields are fixed, so we can pull them out of
-- specific positions in the line.
(m, past_m) = L.splitAt 7 l
(t, past_t) = L.splitAt 4 past_m
(s, past_s) = L.splitAt 40 $ L.tail past_t
f = L.tail past_s