hit-0.4.0: Data/Git/Repository.hs
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE ViewPatterns #-}
-- |
-- Module : Data.Git.Repository
-- License : BSD-style
-- Maintainer : Vincent Hanquez <vincent@snarc.org>
-- Stability : experimental
-- Portability : unix
--
module Data.Git.Repository
( Git
, HTree
, HTreeEnt(..)
, getCommit
, getTree
, rewrite
, buildHTree
, resolvePath
, resolveTreeish
, resolveRevision
, initRepo
, isRepo
) where
import Control.Applicative ((<$>))
import Control.Monad
import Data.Maybe (fromMaybe)
import Data.List (find)
import Data.ByteString (ByteString)
import Data.Git.Named
import Data.Git.Types
import Data.Git.Storage.Object
import Data.Git.Storage
import Data.Git.Revision
import Data.Git.Storage.Loose
import Data.Git.Storage.CacheFile
import Data.Git.Ref
import qualified Data.Map as M
-- | hierarchy tree, either a reference to a blob (file) or a tree (directory).
data HTreeEnt = TreeDir Ref HTree | TreeFile Ref
type HTree = [(Int,ByteString,HTreeEnt)]
-- should be a standard function that do that...
mapJustM f (Just o) = f o
mapJustM _ Nothing = return Nothing
-- | get a specified commit
getCommit :: Git -> Ref -> IO (Maybe Commit)
getCommit git ref = getObject git ref True >>= mapJustM unwrap
where
unwrap (objectToCommit -> Just c@(Commit {})) = return $ Just c
unwrap _ = return Nothing
-- | get a specified tree
getTree :: Git -> Ref -> IO (Maybe Tree)
getTree git ref = getObject git ref True >>= mapJustM unwrap
where
unwrap (objectToTree -> Just c@(Tree {})) = return $ Just c
unwrap _ = return Nothing
-- | try to resolve a string to a specific commit ref
-- for example: HEAD, HEAD^, master~3, shortRef
resolveRevision :: Git -> Revision -> IO (Maybe Ref)
resolveRevision git (Revision prefix modifiers) =
getCacheVal (packedNamed git) >>= \c -> resolvePrefix c >>= modf modifiers
where
resolvePrefix lookupCache = tryResolvers
[resolveNamedPrefix lookupCache namedResolvers
,resolvePrePrefix
]
resolveNamedPrefix _ [] = return Nothing
resolveNamedPrefix lookupCache (x:xs) = followToRef (resolveNamedPrefix lookupCache xs) x
where followToRef onFailure refty = do
exists <- existsRefFile (gitRepoPath git) refty
if exists
then do refcont <- readRefFile (gitRepoPath git) refty
case refcont of
RefDirect ref -> return $ Just ref
RefLink refspecty -> followToRef onFailure refspecty
_ -> error "cannot handle reference content"
else case M.lookup refty lookupCache of
Nothing -> onFailure
y -> return y
namedResolvers = case prefix of
"HEAD" -> [ RefHead ]
"ORIG_HEAD" -> [ RefOrigHead ]
"FETCH_HEAD" -> [ RefFetchHead ]
_ -> [ RefTag prefix, RefBranch prefix, RefRemote prefix ]
tryResolvers :: [IO (Maybe Ref)] -> IO Ref
tryResolvers [] = return $ fromHexString prefix
tryResolvers (resolver:xs) = resolver >>= isResolved
where isResolved (Just r) = return r
isResolved Nothing = tryResolvers xs
resolvePrePrefix :: IO (Maybe Ref)
resolvePrePrefix = do
refs <- findReferencesWithPrefix git prefix
case refs of
[] -> return Nothing
[r] -> return (Just r)
_ -> error "multiple references with this prefix"
modf [] ref = return (Just ref)
modf (RevModParent i:xs) ref = do
parentRefs <- getParentRefs ref
case i of
0 -> error "revision modifier ^0 is not implemented"
_ -> case drop (i - 1) parentRefs of
[] -> error "no such parent"
(p:_) -> modf xs p
modf (RevModParentFirstN 1:xs) ref = modf (RevModParent 1:xs) ref
modf (RevModParentFirstN n:xs) ref = do
parentRefs <- getParentRefs ref
modf (RevModParentFirstN (n-1):xs) (head parentRefs)
modf (_:_) _ = error "unimplemented revision modifier"
getParentRefs ref = do
obj <- getCommit git ref
case obj of
Just (Commit { commitParents = parents }) -> return parents
Nothing -> error "reference in commit chain doesn't exists"
-- | returns a tree from a ref that might be either a commit, a tree or a tag.
resolveTreeish :: Git -> Ref -> IO (Maybe Tree)
resolveTreeish git ref = getObject git ref True >>= mapJustM recToTree where
recToTree (objectToCommit -> Just (Commit { commitTreeish = tree })) = resolveTreeish git tree
recToTree (objectToTag -> Just (Tag tref _ _ _ _)) = resolveTreeish git tref
recToTree (objectToTree -> Just t@(Tree _)) = return $ Just t
recToTree _ = return Nothing
-- | Rewrite a set of commits from a revision and returns the new ref.
--
-- If during revision traversal (diving) there's a commit with zero or multiple
-- parents then the traversal will stop regardless of the amount of parent requested.
--
-- calling "rewrite f 2 (revisionOf d)" on the following tree:
--
-- a <-- b <-- c <-- d
--
-- result in the following tree after mapping with f:
--
-- a <-- f(b) <-- f(c) <-- f(d)
--
rewrite :: Git -- ^ Repository
-> (Commit -> IO Commit) -- ^ Mapping function
-> Revision -- ^ revision to start from
-> Int -- ^ the number of parents to map
-> IO Ref -- ^ return the new head REF
rewrite git mapCommit revision nbParent = do
ref <- fromMaybe (error "revision cannot be found") <$> resolveRevision git revision
resolveParents nbParent ref >>= process . reverse
where resolveParents :: Int -> Ref -> IO [ (Ref, Commit) ]
resolveParents 0 ref = (:[]) . (,) ref . fromMaybe (error "commit cannot be found") <$> getCommit git ref
resolveParents n ref = do commit <- fromMaybe (error "commit cannot be found") <$> getCommit git ref
case commitParents commit of
[parentRef] -> liftM ((ref,commit) :) (resolveParents (n-1) parentRef)
_ -> return [(ref,commit)]
process [] = error "nothing to rewrite"
process ((_,commit):next) =
mapCommit commit >>= looseWrite (gitRepoPath git) . toObject >>= flip rewriteOne next
rewriteOne prevRef [] = return prevRef
rewriteOne prevRef ((_,commit):next) = do
newCommit <- mapCommit $ commit { commitParents = [prevRef] }
ref <- looseWrite (gitRepoPath git) (toObject newCommit)
rewriteOne ref next
-- | build a hierarchy tree from a tree object
buildHTree :: Git -> Tree -> IO HTree
buildHTree git (Tree ents) = mapM resolveTree ents
where resolveTree (perm, ent, ref) = do
obj <- getObjectType git ref
case obj of
Just TypeBlob -> return (perm, ent, TreeFile ref)
Just TypeTree -> do
ctree <- getTree git ref
case ctree of
Nothing -> error "unknown reference in tree object: no such child"
Just t -> do
dir <- buildHTree git t
return (perm, ent, TreeDir ref dir)
Just _ -> error "wrong type embedded in tree object"
Nothing -> error "unknown reference in tree object"
-- | resolve the ref (tree or blob) related to a path at a specific commit ref
resolvePath :: Git -- ^ repository
-> Ref -- ^ commit reference
-> [ByteString] -- ^ paths
-> IO (Maybe Ref)
resolvePath git commitRef paths = do
commit <- getCommit git commitRef
case commit of
Just (Commit { commitTreeish = tree }) -> resolve tree paths
Nothing -> error ("not a valid commit ref: " ++ show commitRef)
where
resolve :: Ref -> [ByteString] -> IO (Maybe Ref)
resolve treeRef [] = return $ Just treeRef
resolve treeRef (x:xs) = do
tree <- getTree git treeRef
case tree of
Just (Tree ents) -> do
let cEnt = treeEntRef <$> findEnt x ents
if xs == []
then return cEnt
else maybe (return Nothing) (\z -> resolve z xs) cEnt
Nothing -> error ("not a valid tree ref: " ++ show treeRef)
findEnt x = find (\(_, b, _) -> b == x)
treeEntRef (_,_,r) = r