git-annex/Git/History.hs
2019-05-01 13:38:40 -04:00

105 lines
2.8 KiB
Haskell

{-# LANGUAGE BangPatterns #-}
{- git commit history interface
-
- Copyright 2019 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Git.History where
import Common
import Git
import Git.Command
import Git.Sha
import qualified Data.Set as S
data History t = History t (S.Set (History t))
deriving (Show, Eq, Ord)
mapHistory :: (Ord a, Ord b) => (a -> b) -> History a -> History b
mapHistory f (History t s) = History (f t) (S.map (mapHistory f) s)
historyDepth :: History t -> Integer
historyDepth (History _ s)
| S.null s = 1
| otherwise = 1 + maximum (map historyDepth (S.toList s))
truncateHistoryToDepth :: Ord t => Integer -> History t -> History t
truncateHistoryToDepth n (History t ps) = History t (go 1 ps)
where
go depth s
| depth >= n = S.empty
| otherwise =
let depth' = succ depth
in flip S.map s $ \(History t' s') ->
History t' (go depth' s')
data HistoryCommit = HistoryCommit
{ historyCommit :: Sha
, historyCommitTree :: Sha
, historyCommitParents :: [Sha]
} deriving (Show, Eq, Ord)
{- Gets a History starting with the provided commit, and down to the
- requested depth. -}
getHistoryToDepth :: Integer -> Ref -> Repo -> IO (Maybe (History HistoryCommit))
getHistoryToDepth n commit r = do
(_, Just inh, _, pid) <- createProcess (gitCreateProcess params r)
{ std_out = CreatePipe }
!h <- fmap (truncateHistoryToDepth n)
. build Nothing
. map parsehistorycommit
. lines
<$> hGetContents inh
hClose inh
void $ waitForProcess pid
return h
where
build h [] = fmap (mapHistory fst) h
build _ (Nothing:_) = Nothing
build Nothing (Just v:rest) =
build (Just (History v S.empty)) rest
build (Just h) (Just v:rest) =
let h' = traverseadd v h
in build (Just h') $
-- detect when all parents down to desired depth
-- have been found, and avoid processing any more,
-- this makes it much faster when there is a lot of
-- history.
if parentsfound h' then [] else rest
traverseadd v@(hc, _ps) (History v'@(hc', ps') s)
| historyCommit hc `elem` ps' =
let ps'' = filter (/= historyCommit hc) ps'
in History (hc', ps'') (S.insert (History v S.empty) s)
| otherwise = History v' (S.map (traverseadd v) s)
parentsfound = parentsfound' 1
parentsfound' depth (History (_hc, ps) s)
| not (null ps) = False
| null ps && depth == n = True
| depth >= n = True
| otherwise = all (parentsfound' (succ depth)) (S.toList s)
params =
[ Param "log"
, Param (fromRef commit)
, Param "--full-history"
, Param "--no-abbrev"
, Param "--format=%T %H %P"
]
parsehistorycommit l = case map extractSha (splitc ' ' l) of
(Just t:Just c:ps) -> Just $
( HistoryCommit
{ historyCommit = c
, historyCommitTree = t
, historyCommitParents = catMaybes ps
}
, catMaybes ps
)
_ -> Nothing