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|
{- git branch stuff
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE BangPatterns #-}
module Git.Branch where
import Common
import Git
import Git.Sha
import Git.Command
import qualified Git.Ref
{- The currently checked out branch.
-
- In a just initialized git repo before the first commit,
- symbolic-ref will show the master branch, even though that
- branch is not created yet. So, this also looks at show-ref HEAD
- to double-check.
-}
current :: Repo -> IO (Maybe Git.Ref)
current r = do
v <- currentUnsafe r
case v of
Nothing -> return Nothing
Just branch ->
ifM (null <$> pipeReadStrict [Param "show-ref", Param $ fromRef branch] r)
( return Nothing
, return v
)
{- The current branch, which may not really exist yet. -}
currentUnsafe :: Repo -> IO (Maybe Git.Ref)
currentUnsafe r = parse . firstLine
<$> pipeReadStrict [Param "symbolic-ref", Param $ fromRef Git.Ref.headRef] r
where
parse l
| null l = Nothing
| otherwise = Just $ Git.Ref l
{- Checks if the second branch has any commits not present on the first
- branch. -}
changed :: Branch -> Branch -> Repo -> IO Bool
changed origbranch newbranch repo
| origbranch == newbranch = return False
| otherwise = not . null <$> diffs
where
diffs = pipeReadStrict
[ Param "log"
, Param (fromRef origbranch ++ ".." ++ fromRef newbranch)
, Param "-n1"
, Param "--pretty=%H"
] repo
{- Check if it's possible to fast-forward from the old
- ref to the new ref.
-
- This requires there to be a path from the old to the new. -}
fastForwardable :: Ref -> Ref -> Repo -> IO Bool
fastForwardable old new repo = not . null <$>
pipeReadStrict
[ Param "log"
, Param $ fromRef old ++ ".." ++ fromRef new
, Param "-n1"
, Param "--pretty=%H"
, Param "--ancestry-path"
] repo
{- Given a set of refs that are all known to have commits not
- on the branch, tries to update the branch by a fast-forward.
-
- In order for that to be possible, one of the refs must contain
- every commit present in all the other refs.
-}
fastForward :: Branch -> [Ref] -> Repo -> IO Bool
fastForward _ [] _ = return True
fastForward branch (first:rest) repo =
-- First, check that the branch does not contain any
-- new commits that are not in the first ref. If it does,
-- cannot fast-forward.
ifM (changed first branch repo)
( no_ff
, maybe no_ff do_ff =<< findbest first rest
)
where
no_ff = return False
do_ff to = do
update branch to repo
return True
findbest c [] = return $ Just c
findbest c (r:rs)
| c == r = findbest c rs
| otherwise = do
better <- changed c r repo
worse <- changed r c repo
case (better, worse) of
(True, True) -> return Nothing -- divergent fail
(True, False) -> findbest r rs -- better
(False, True) -> findbest c rs -- worse
(False, False) -> findbest c rs -- same
{- Commits the index into the specified branch (or other ref),
- with the specified parent refs, and returns the committed sha.
-
- Without allowempy set, avoids making a commit if there is exactly
- one parent, and it has the same tree that would be committed.
-
- Unlike git-commit, does not run any hooks, or examine the work tree
- in any way.
-}
commit :: Bool -> String -> Branch -> [Ref] -> Repo -> IO (Maybe Sha)
commit allowempty message branch parentrefs repo = do
tree <- getSha "write-tree" $
pipeReadStrict [Param "write-tree"] repo
ifM (cancommit tree)
( do
sha <- getSha "commit-tree" $ pipeWriteRead
(map Param $ ["commit-tree", fromRef tree] ++ ps)
(Just $ flip hPutStr message) repo
update branch sha repo
return $ Just sha
, return Nothing
)
where
ps = concatMap (\r -> ["-p", fromRef r]) parentrefs
cancommit tree
| allowempty = return True
| otherwise = case parentrefs of
[p] -> maybe False (tree /=) <$> Git.Ref.tree p repo
_ -> return True
commitAlways :: String -> Branch -> [Ref] -> Repo -> IO Sha
commitAlways message branch parentrefs repo = fromJust
<$> commit True message branch parentrefs repo
{- A leading + makes git-push force pushing a branch. -}
forcePush :: String -> String
forcePush b = "+" ++ b
{- Updates a branch (or other ref) to a new Sha. -}
update :: Branch -> Sha -> Repo -> IO ()
update branch sha = run
[ Param "update-ref"
, Param $ fromRef branch
, Param $ fromRef sha
]
{- Checks out a branch, creating it if necessary. -}
checkout :: Branch -> Repo -> IO ()
checkout branch = run
[ Param "checkout"
, Param "-q"
, Param "-B"
, Param $ fromRef $ Git.Ref.base branch
]
{- Removes a branch. -}
delete :: Branch -> Repo -> IO ()
delete branch = run
[ Param "branch"
, Param "-q"
, Param "-D"
, Param $ fromRef $ Git.Ref.base branch
]
|
