9eb10caa27
Turns out that Data.List.Utils.split is slow and makes a lot of allocations. Here's a much simpler single character splitter that behaves the same (even in wacky corner cases) while running in half the time and 75% the allocations. As well as being an optimisation, this helps move toward eliminating use of missingh. (Data.List.Split.splitOn is nearly as slow as Data.List.Utils.split and allocates even more.) I have not benchmarked the effect on git-annex, but would not be surprised to see some parsing of eg, large streams from git commands run twice as fast, and possibly in less memory. This commit was sponsored by Boyd Stephen Smith Jr. on Patreon.
38 lines
1 KiB
Haskell
38 lines
1 KiB
Haskell
{- dotted versions, such as 1.0.1
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-
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- Copyright 2011-2014 Joey Hess <id@joeyh.name>
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-
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- License: BSD-2-clause
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-}
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{-# OPTIONS_GHC -fno-warn-tabs #-}
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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 $ splitc '.' 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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