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|
{- git-union-merge library
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Git.UnionMerge (
merge,
merge_index,
update_index,
update_index_line,
ls_tree
) where
import System.Cmd.Utils
import Data.List
import Data.Maybe
import Data.String.Utils
import qualified Data.ByteString.Lazy.Char8 as L
import Common
import Git
{- Performs a union merge between two branches, staging it in the index.
- Any previously staged changes in the index will be lost.
-
- Should be run with a temporary index file configured by Git.useIndex.
-}
merge :: Repo -> String -> String -> IO ()
merge g x y = do
a <- ls_tree g x
b <- merge_trees g x y
update_index g (a++b)
{- Merges a list of branches into the index. Previously staged changed in
- the index are preserved (and participate in the merge). -}
merge_index :: Repo -> [String] -> IO ()
merge_index g bs = update_index g =<< concat <$> mapM (merge_tree_index g) bs
{- Feeds a list into update-index. Later items in the list can override
- earlier ones, so the list can be generated from any combination of
- ls_tree, merge_trees, and merge_tree_index. -}
update_index :: Repo -> [String] -> IO ()
update_index g l = togit ["update-index", "-z", "--index-info"] (join "\0" l)
where
togit ps content = pipeWrite g (map Param ps) (L.pack content)
>>= forceSuccess
{- Generates a line suitable to be fed into update-index, to add
- a given file with a given sha. -}
update_index_line :: String -> FilePath -> String
update_index_line sha file = "100644 blob " ++ sha ++ "\t" ++ file
{- Gets the contents of a tree in a format suitable for update_index. -}
ls_tree :: Repo -> String -> IO [String]
ls_tree g x = pipeNullSplit g $
map Param ["ls-tree", "-z", "-r", "--full-tree", x]
{- For merging two trees. -}
merge_trees :: Repo -> String -> String -> IO [String]
merge_trees g x y = calc_merge g $ "diff-tree":diff_opts ++ [x, y]
{- For merging a single tree into the index. -}
merge_tree_index :: Repo -> String -> IO [String]
merge_tree_index g x = calc_merge g $ "diff-index":diff_opts ++ ["--cached", x]
diff_opts :: [String]
diff_opts = ["--raw", "-z", "-r", "--no-renames", "-l0"]
{- Calculates how to perform a merge, using git to get a raw diff,
- and returning a list suitable for update_index. -}
calc_merge :: Repo -> [String] -> IO [String]
calc_merge g differ = do
diff <- pipeNullSplit g $ map Param differ
l <- mapM (mergeFile g) (pairs diff)
return $ catMaybes l
where
pairs [] = []
pairs (_:[]) = error "calc_merge parse error"
pairs (a:b:rest) = (a,b):pairs rest
{- Injects some content into git, returning its hash. -}
hashObject :: Repo -> L.ByteString -> IO String
hashObject repo content = getSha subcmd $ do
(h, s) <- pipeWriteRead repo (map Param params) content
L.length s `seq` do
forceSuccess h
reap -- XXX unsure why this is needed
return $ L.unpack s
where
subcmd = "hash-object"
params = [subcmd, "-w", "--stdin"]
{- Given an info line from a git raw diff, and the filename, generates
- a line suitable for update_index that union merges the two sides of the
- diff. -}
mergeFile :: Repo -> (String, FilePath) -> IO (Maybe String)
mergeFile g (info, file) = case filter (/= nullsha) [asha, bsha] of
[] -> return Nothing
(sha:[]) -> return $ Just $ update_index_line sha file
shas -> do
content <- pipeRead g $ map Param ("show":shas)
sha <- hashObject g $ unionmerge content
return $ Just $ update_index_line sha file
where
[_colonamode, _bmode, asha, bsha, _status] = words info
nullsha = replicate shaSize '0'
unionmerge = L.unlines . nub . L.lines
|
