36 lines
1,007 B
Haskell
36 lines
1,007 B
Haskell
{- dotted versions, such as 1.0.1
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-
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- Copyright 2011-2014 Joey Hess <joey@kitenet.net>
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-
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- License: BSD-2-clause
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-}
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module Utility.DottedVersion where
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import Common
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data DottedVersion = DottedVersion String Integer
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deriving (Eq)
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instance Ord DottedVersion where
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compare (DottedVersion _ x) (DottedVersion _ y) = compare x y
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instance Show DottedVersion where
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show (DottedVersion s _) = s
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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 -> DottedVersion
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normalize v = DottedVersion 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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