Initial implementation of Darcs patch reader
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fr33domlover
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c8b085fbc8
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7782e83419
1 changed files with 79 additions and 40 deletions
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@ -31,23 +31,29 @@ import Darcs.Util.Path
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import Darcs.Util.Tree
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import Darcs.Util.Tree.Hashed
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import Data.Bool (bool)
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import Data.Maybe (listToMaybe, mapMaybe)
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import Data.List.NonEmpty (NonEmpty (..))
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import Data.Maybe (listToMaybe, mapMaybe, fromMaybe)
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import Data.Text (Text)
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import Data.Text.Encoding (encodeUtf8, decodeUtf8With)
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import Data.Text.Encoding (encodeUtf8, decodeUtf8With, decodeUtf8)
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import Data.Text.Encoding.Error (strictDecode)
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import Data.Time.Clock (UTCTime, getCurrentTime, diffUTCTime)
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import Data.Traversable (for)
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import Development.Darcs.Internal.Hash.Codec
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import Development.Darcs.Internal.Hash.Types
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import Development.Darcs.Internal.Inventory.Parser
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import Development.Darcs.Internal.Inventory.Read
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import Development.Darcs.Internal.Inventory.Types
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import Development.Darcs.Internal.Patch.Types
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import System.FilePath ((</>))
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import Text.Email.Validate (emailAddress)
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import qualified Data.Attoparsec.Text as A
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import qualified Data.ByteString.Lazy as BL (ByteString)
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import qualified Data.ByteString.Base16 as B16 (encode)
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import qualified Data.ByteString.Base16 as B16 (encode, decode)
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import qualified Data.Foldable as F (find)
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import qualified Data.Text as T (takeWhile, stripEnd)
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import qualified Data.Text as T (unpack, takeWhile, stripEnd)
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import qualified Data.Vector as V (empty)
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import qualified Development.Darcs.Internal.Patch.Parser as P
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import Darcs.Local.Repository
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import Data.Either.Local (maybeRight)
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@ -221,40 +227,73 @@ lastChange path now = fmap maybeRight $ runExceptT $ do
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FriendlyConvert $
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now `diffUTCTime` piTime pi
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-- TODO
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-- | Read patch content, both metadata and the actual diff, from a given Darcs
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-- repository. Preconditions:
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--
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-- * The repository is assumed to exist. If it doesn't, an exception is thrown.
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-- * The repository is assumed to be in a consistent state, all the expected
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-- inventory files and patch files and so on are assumed to exist and have
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-- the expected format. If not, an exception is thrown.
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-- * The hash may or may not be found in the repo. If there's no patch in the
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-- repo with the given hash, 'Nothing' is returned.
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readPatch :: FilePath -> Text -> IO (Maybe Patch)
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readPatch path hash = error "Not implemented"
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-- I'm not sure what's the fastest way to find a patch file given its info
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-- hash, maybe Darcs keeps some cache or something. But assuming there are
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-- no tricks like that, here's an idea how to grab the patch:
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--
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-- (1) Start going over the whole inventory, whose order is from latest to
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-- oldest, looking for a patch with the given hash.
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-- (2) Once found, determine the patch filename from its size and content
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-- hash
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-- (3) Run the patch parser on that file, through a zlib decompressor
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-- though (check how I did that for the inventories parser)
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--
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-- TODO idea: Use hints to speed up finding the patch! In the repo history
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-- log page, embed hints into the hyperlinks to the patches, and in the
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-- patch page handler, use the hint to figure out the patch location.
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-- Actually, since the inventory file contains patch content hashes, I can
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-- use that as a hint and skip the whole step of looking for the patch!
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--
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-- TODO maybe start by finding the patch hash in patch_ids and use the
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-- position as a hint to its location in the inventories
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--
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-- TODO maybe I can figure out from darcs source code how a given patch
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-- hash is found? Just in case there's a faster way
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--
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-- TODO find out what's the index and patch_index files under _darcs and
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-- maybe other files there, possibly there's a way to patch the info hash
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-- with the content hash.
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--
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-- UPDATE: I read about index and patch_index, looks like they won't help.
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-- But possibly the global cache system will? However interesting note:
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-- Vervis on my laptop has a patch_index, but on the server it doesn't.
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-- Probably because `darcs log` never runs on the server since I parse
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-- patches manually. If I end up using the patch index for something, it
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-- may be a good idea to trigger its generation, so that it's available
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-- when people browser repo pages.
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readPatch path hash = do
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let pih = PatchInfoHash $ fst $ B16.decode $ encodeUtf8 hash
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li <- handle =<< readLatestInventory path latestInventoryAllP
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mp <- loop pih (liPatches li) (fst <$> liPrevTag li)
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for mp $ \ (pi, pch) -> do
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(_pir, hunks) <- handle =<< readCompressedPatch path pch P.patch
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let (an, ae) =
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either error id $
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A.parseOnly (author <* A.endOfInput) $ piAuthor pi
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return Patch
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{ patchAuthorName = an
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, patchAuthorEmail = ae
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, patchTime = piTime pi
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, patchTitle = piTitle pi
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, patchDescription = fromMaybe "" $ piDescription pi
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, patchDiff = map mkedit hunks
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}
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where
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handle = either (const $ fail "readPatch failed") pure
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lookup' pih ps = case F.find (\ (_pi, pih', _pch) -> pih' == pih) ps of
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Nothing -> Nothing
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Just (pi, _pih, pch) -> Just (pi, pch)
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loop pih ps mih = case lookup' pih ps of
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Just p -> return $ Just p
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Nothing -> case mih of
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Nothing -> return Nothing
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Just ih -> do
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i <- handle =<< readCompressedInventory path ih earlyInventoryAllP
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case i of
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Left ei -> loop pih (eiPatches ei) Nothing
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Right mi -> loop pih (miPatches mi) (Just $ miPrevious mi)
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email = maybe (fail "invalid email") pure . emailAddress . encodeUtf8
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author = (,)
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<$> A.takeWhile1 (const True)
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<* " <"
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<*> (A.takeWhile1 (/= '>') >>= email)
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<* A.skip (== '>')
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mkhunk h = case P.hunkRemove h of
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[] -> Hunk
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{ hunkAddFirst = map decodeUtf8 $ P.hunkAdd h
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, hunkRemoveAdd = []
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, hunkRemoveLast = []
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}
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r:rs -> case P.hunkAdd h of
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[] -> Hunk
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{ hunkAddFirst = []
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, hunkRemoveAdd = []
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, hunkRemoveLast = map decodeUtf8 $ r : rs
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}
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a:as -> Hunk
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{ hunkAddFirst = []
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, hunkRemoveAdd = [(decodeUtf8 <$> r :| rs, decodeUtf8 <$> a :| as)]
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, hunkRemoveLast = []
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}
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mkedit hunk =
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EditTextFile
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(T.unpack $ decodeUtf8 $ P.hunkFile hunk)
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V.empty
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((False, P.hunkLine hunk, mkhunk hunk) :| [])
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0 0
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