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