43 lines
1.1 KiB
Haskell
43 lines
1.1 KiB
Haskell
{- git versions
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-
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- Copyright 2011, 2013 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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data GitVersion = GitVersion String Integer
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deriving (Eq)
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instance Ord GitVersion where
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compare (GitVersion _ x) (GitVersion _ y) = compare x y
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instance Show GitVersion where
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show (GitVersion s _) = s
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installed :: IO GitVersion
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installed = normalize . extract <$> readProcess "git" ["--version"]
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where
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extract s = case lines s of
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[] -> ""
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(l:_) -> unwords $ drop 2 $ words l
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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 -> GitVersion
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normalize v = GitVersion v $
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sum $ mult 1 $ reverse $ extend precision $ take precision $
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map readi $ split "." v
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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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