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{- git version checking
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Git.Version where
import Common
import qualified Build.SysConfig
{- Using the version it was configured for avoids running git to check its
- version, at the cost that upgrading git won't be noticed.
- This is only acceptable because it's rare that git's version influences
- code's behavior. -}
version :: String
version = Build.SysConfig.gitversion
older :: String -> Bool
older v = normalize version < normalize v
{- To compare dotted versions like 1.7.7 and 1.8, they are normalized to
- a somewhat arbitrary integer representation. -}
normalize :: String -> Integer
normalize = sum . mult 1 . reverse .
extend precision . take precision .
map readi . split "."
where
extend n l = l ++ replicate (n - length l) 0
mult _ [] = []
mult n (x:xs) = (n*x) : mult (n*10^width) xs
readi :: String -> Integer
readi s = case reads s of
((x,_):_) -> x
_ -> 0
precision = 10 -- number of segments of the version to compare
width = length "yyyymmddhhmmss" -- maximum width of a segment
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