{- data size display and parsing - - Copyright 2011 Joey Hess - - License: BSD-2-clause - - - And now a rant: - - In the beginning, we had powers of two, and they were good. - - Disk drive manufacturers noticed that some powers of two were - sorta close to some powers of ten, and that rounding down to the nearest - power of ten allowed them to advertise their drives were bigger. This - was sorta annoying. - - Then drives got big. Really, really big. This was good. - - Except that the small rounding error perpretrated by the drive - manufacturers suffered the fate of a small error, and became a large - error. This was bad. - - So, a committee was formed. And it arrived at a committee-like decision, - which satisfied noone, confused everyone, and made the world an uglier - place. As with all committees, this was meh. - - And the drive manufacturers happily continued selling drives that are - increasingly smaller than you'd expect, if you don't count on your - fingers. But that are increasingly too big for anyone to much notice. - This caused me to need git-annex. - - Thus, I use units here that I loathe. Because if I didn't, people would - be confused that their drives seem the wrong size, and other people would - complain at me for not being standards compliant. And we call this - progress? -} module Utility.DataUnits ( dataUnits, storageUnits, memoryUnits, bandwidthUnits, oldSchoolUnits, Unit(..), ByteSize, roughSize, compareSizes, readSize ) where import Data.List import Data.Char import Utility.HumanNumber type ByteSize = Integer type Name = String type Abbrev = String data Unit = Unit ByteSize Abbrev Name deriving (Ord, Show, Eq) dataUnits :: [Unit] dataUnits = storageUnits ++ memoryUnits {- Storage units are (stupidly) powers of ten. -} storageUnits :: [Unit] storageUnits = [ Unit (p 8) "YB" "yottabyte" , Unit (p 7) "ZB" "zettabyte" , Unit (p 6) "EB" "exabyte" , Unit (p 5) "PB" "petabyte" , Unit (p 4) "TB" "terabyte" , Unit (p 3) "GB" "gigabyte" , Unit (p 2) "MB" "megabyte" , Unit (p 1) "kB" "kilobyte" -- weird capitalization thanks to committe , Unit (p 0) "B" "byte" ] where p :: Integer -> Integer p n = 1000^n {- Memory units are (stupidly named) powers of 2. -} memoryUnits :: [Unit] memoryUnits = [ Unit (p 8) "YiB" "yobibyte" , Unit (p 7) "ZiB" "zebibyte" , Unit (p 6) "EiB" "exbibyte" , Unit (p 5) "PiB" "pebibyte" , Unit (p 4) "TiB" "tebibyte" , Unit (p 3) "GiB" "gibibyte" , Unit (p 2) "MiB" "mebibyte" , Unit (p 1) "KiB" "kibibyte" , Unit (p 0) "B" "byte" ] where p :: Integer -> Integer p n = 2^(n*10) {- Bandwidth units are only measured in bits if you're some crazy telco. -} bandwidthUnits :: [Unit] bandwidthUnits = error "stop trying to rip people off" {- Do you yearn for the days when men were men and megabytes were megabytes? -} oldSchoolUnits :: [Unit] oldSchoolUnits = zipWith (curry mingle) storageUnits memoryUnits where mingle (Unit _ a n, Unit s' _ _) = Unit s' a n {- approximate display of a particular number of bytes -} roughSize :: [Unit] -> Bool -> ByteSize -> String roughSize units short i | i < 0 = '-' : findUnit units' (negate i) | otherwise = findUnit units' i where units' = sortBy (flip compare) units -- largest first findUnit (u@(Unit s _ _):us) i' | i' >= s = showUnit i' u | otherwise = findUnit us i' findUnit [] i' = showUnit i' (last units') -- bytes showUnit x (Unit size abbrev name) = s ++ " " ++ unit where v = (fromInteger x :: Double) / fromInteger size s = showImprecise 2 v unit | short = abbrev | s == "1" = name | otherwise = name ++ "s" {- displays comparison of two sizes -} compareSizes :: [Unit] -> Bool -> ByteSize -> ByteSize -> String compareSizes units abbrev old new | old > new = roughSize units abbrev (old - new) ++ " smaller" | old < new = roughSize units abbrev (new - old) ++ " larger" | otherwise = "same" {- Parses strings like "10 kilobytes" or "0.5tb". -} readSize :: [Unit] -> String -> Maybe ByteSize readSize units input | null parsednum || null parsedunit = Nothing | otherwise = Just $ round $ number * fromIntegral multiplier where (number, rest) = head parsednum multiplier = head parsedunit unitname = takeWhile isAlpha $ dropWhile isSpace rest parsednum = reads input :: [(Double, String)] parsedunit = lookupUnit units unitname lookupUnit _ [] = [1] -- no unit given, assume bytes lookupUnit [] _ = [] lookupUnit (Unit s a n:us) v | a ~~ v || n ~~ v = [s] | plural n ~~ v || a ~~ byteabbrev v = [s] | otherwise = lookupUnit us v a ~~ b = map toLower a == map toLower b plural n = n ++ "s" byteabbrev a = a ++ "b"