git-annex/Types/RefSpec.hs
Joey Hess 9eb10caa27
Some optimisations to string splitting code.
Turns out that Data.List.Utils.split is slow and makes a lot of
allocations. Here's a much simpler single character splitter that behaves
the same (even in wacky corner cases) while running in half the time and
75% the allocations.

As well as being an optimisation, this helps move toward eliminating use of
missingh.

(Data.List.Split.splitOn is nearly as slow as Data.List.Utils.split and
allocates even more.)

I have not benchmarked the effect on git-annex, but would not be surprised
to see some parsing of eg, large streams from git commands run twice as
fast, and possibly in less memory.

This commit was sponsored by Boyd Stephen Smith Jr. on Patreon.
2017-01-31 19:06:22 -04:00

52 lines
1.4 KiB
Haskell

{- This is not the same as git's fetch/push refspecs.
-
- Copyright 2015 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Types.RefSpec where
import Common
import Utility.Glob
import Git.Types
import Data.Either
type RefSpec = [RefSpecPart]
data RefSpecPart
= AddRef Ref
| AddMatching Glob
| AddRefLog
| RemoveMatching Glob
allRefSpec :: RefSpec
allRefSpec = [AddMatching $ compileGlob "*" CaseSensative]
parseRefSpec :: String -> Either String RefSpec
parseRefSpec v = case partitionEithers (map mk $ splitc ':' v) of
([],refspec) -> Right refspec
(e:_,_) -> Left e
where
mk ('+':s)
| any (`elem` s) "*?" =
Right $ AddMatching $ compileGlob s CaseSensative
| otherwise = Right $ AddRef $ Ref s
mk ('-':s) = Right $ RemoveMatching $ compileGlob s CaseSensative
mk "reflog" = Right AddRefLog
mk s = Left $ "bad refspec item \"" ++ s ++ "\" (expected + or - prefix)"
applyRefSpec :: Monad m => RefSpec -> [Ref] -> m [Sha] -> m [Ref]
applyRefSpec refspec rs getreflog = go [] refspec
where
go c [] = return (reverse c)
go c (AddRef r : rest) = go (r:c) rest
go c (AddMatching g : rest) =
let add = filter (matchGlob g . fromRef) rs
in go (add ++ c) rest
go c (AddRefLog : rest) = do
reflog <- getreflog
go (reflog ++ c) rest
go c (RemoveMatching g : rest) =
go (filter (not . matchGlob g . fromRef) c) rest