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{- dotted versions, such as 1.0.1
-
- Copyright 2011-2014 Joey Hess <id@joeyh.name>
-
- License: BSD-2-clause
-}
{-# OPTIONS_GHC -fno-warn-tabs #-}
module Utility.DottedVersion where
import Common
data DottedVersion = DottedVersion String Integer
deriving (Eq)
instance Ord DottedVersion where
compare (DottedVersion _ x) (DottedVersion _ y) = compare x y
instance Show DottedVersion where
show (DottedVersion s _) = s
{- To compare dotted versions like 1.7.7 and 1.8, they are normalized to
- a somewhat arbitrary integer representation. -}
normalize :: String -> DottedVersion
normalize v = DottedVersion v $
sum $ mult 1 $ reverse $ extend precision $ take precision $
map readi $ split "." v
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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