src/Maskbits.hs

   1 module Maskbits
   2 ( Maskbits(..),
   3   decrement,
   4   maskbits_from_string
   5 ) where
   6
   7 import Test.QuickCheck
   8
   9 -- | A type representing the number of bits in a CIDR netmask.
  10 data Maskbits =
  11     Zero
  12   | One
  13   | Two
  14   | Three
  15   | Four
  16   | Five
  17   | Six
  18   | Seven
  19   | Eight
  20   | Nine
  21   | Ten
  22   | Eleven
  23   | Twelve
  24   | Thirteen
  25   | Fourteen
  26   | Fifteen
  27   | Sixteen
  28   | Seventeen
  29   | Eighteen
  30   | Nineteen
  31   | Twenty
  32   | TwentyOne
  33   | TwentyTwo
  34   | TwentyThree
  35   | TwentyFour
  36   | TwentyFive
  37   | TwentySix
  38   | TwentySeven
  39   | TwentyEight
  40   | TwentyNine
  41   | Thirty
  42   | ThirtyOne
  43   | ThirtyTwo
  44     deriving (Eq, Ord)
  45
  46
  47 instance Show Maskbits where
  48   show Zero        = "0"
  49   show One         = "1"
  50   show Two         = "2"
  51   show Three       = "3"
  52   show Four        = "4"
  53   show Five        = "5"
  54   show Six         = "6"
  55   show Seven       = "7"
  56   show Eight       = "8"
  57   show Nine        = "9"
  58   show Ten         = "10"
  59   show Eleven      = "11"
  60   show Twelve      = "12"
  61   show Thirteen    = "13"
  62   show Fourteen    = "14"
  63   show Fifteen     = "15"
  64   show Sixteen     = "16"
  65   show Seventeen   = "17"
  66   show Eighteen    = "18"
  67   show Nineteen    = "19"
  68   show Twenty      = "20"
  69   show TwentyOne   = "21"
  70   show TwentyTwo   = "22"
  71   show TwentyThree = "23"
  72   show TwentyFour  = "24"
  73   show TwentyFive  = "25"
  74   show TwentySix   = "26"
  75   show TwentySeven = "27"
  76   show TwentyEight = "28"
  77   show TwentyNine  = "29"
  78   show Thirty      = "30"
  79   show ThirtyOne   = "31"
  80   show ThirtyTwo   = "32"
  81
  82
  83 instance Arbitrary Maskbits where
  84   arbitrary =
  85     elements [ Zero,
  86                One,
  87                Two,
  88                Three,
  89                Four,
  90                Five,
  91                Six,
  92                Seven,
  93                Eight,
  94                Nine,
  95                Ten,
  96                Eleven,
  97                Twelve,
  98                Thirteen,
  99                Fourteen,
 100                Fifteen,
 101                Sixteen,
 102                Seventeen,
 103                Eighteen,
 104                Nineteen,
 105                Twenty,
 106                TwentyOne,
 107                TwentyTwo,
 108                TwentyThree,
 109                TwentyFour,
 110                TwentyFive,
 111                TwentySix,
 112                TwentySeven,
 113                TwentyEight,
 114                TwentyNine,
 115                Thirty,
 116                ThirtyOne,
 117                ThirtyTwo ]
 118
 119
 120
 121 -- | There are only 32 bits in an IPv4 address, so there
 122 --   can't be more bits than that in the mask.
 123 maskbits_from_int :: Int -> Maybe Maskbits
 124 maskbits_from_int 0  = Just Zero
 125 maskbits_from_int 1  = Just One
 126 maskbits_from_int 2  = Just Two
 127 maskbits_from_int 3  = Just Three
 128 maskbits_from_int 4  = Just Four
 129 maskbits_from_int 5  = Just Five
 130 maskbits_from_int 6  = Just Six
 131 maskbits_from_int 7  = Just Seven
 132 maskbits_from_int 8  = Just Eight
 133 maskbits_from_int 9  = Just Nine
 134 maskbits_from_int 10 = Just Ten
 135 maskbits_from_int 11 = Just Eleven
 136 maskbits_from_int 12 = Just Twelve
 137 maskbits_from_int 13 = Just Thirteen
 138 maskbits_from_int 14 = Just Fourteen
 139 maskbits_from_int 15 = Just Fifteen
 140 maskbits_from_int 16 = Just Sixteen
 141 maskbits_from_int 17 = Just Seventeen
 142 maskbits_from_int 18 = Just Eighteen
 143 maskbits_from_int 19 = Just Nineteen
 144 maskbits_from_int 20 = Just Twenty
 145 maskbits_from_int 21 = Just TwentyOne
 146 maskbits_from_int 22 = Just TwentyTwo
 147 maskbits_from_int 23 = Just TwentyThree
 148 maskbits_from_int 24 = Just TwentyFour
 149 maskbits_from_int 25 = Just TwentyFive
 150 maskbits_from_int 26 = Just TwentySix
 151 maskbits_from_int 27 = Just TwentySeven
 152 maskbits_from_int 28 = Just TwentyEight
 153 maskbits_from_int 29 = Just TwentyNine
 154 maskbits_from_int 30 = Just Thirty
 155 maskbits_from_int 31 = Just ThirtyOne
 156 maskbits_from_int 32 = Just ThirtyTwo
 157 maskbits_from_int _  = Nothing
 158
 159
 160 -- | Convert a String to Maskbits, if possible.
 161 maskbits_from_string :: String -> Maybe Maskbits
 162 maskbits_from_string s =
 163   case (reads s :: [(Int, String)]) of
 164     []   -> Nothing
 165     x:_ -> maskbits_from_int (fst x)
 166
 167
 168
 169 -- | Maskbits are just natural numbers, this returns the previous one.
 170 decrement :: Maskbits -> Maskbits
 171 decrement Zero = Zero
 172 decrement One = Zero
 173 decrement Two = One
 174 decrement Three = Two
 175 decrement Four = Three
 176 decrement Five = Four
 177 decrement Six = Five
 178 decrement Seven = Six
 179 decrement Eight = Seven
 180 decrement Nine = Eight
 181 decrement Ten = Nine
 182 decrement Eleven = Ten
 183 decrement Twelve = Eleven
 184 decrement Thirteen = Twelve
 185 decrement Fourteen = Thirteen
 186 decrement Fifteen = Fourteen
 187 decrement Sixteen = Fifteen
 188 decrement Seventeen = Sixteen
 189 decrement Eighteen = Seventeen
 190 decrement Nineteen = Eighteen
 191 decrement Twenty = Nineteen
 192 decrement TwentyOne = Twenty
 193 decrement TwentyTwo = TwentyOne
 194 decrement TwentyThree = TwentyTwo
 195 decrement TwentyFour = TwentyThree
 196 decrement TwentyFive = TwentyFour
 197 decrement TwentySix = TwentyFive
 198 decrement TwentySeven = TwentySix
 199 decrement TwentyEight = TwentySeven
 200 decrement TwentyNine = TwentyEight
 201 decrement Thirty = TwentyNine
 202 decrement ThirtyOne = Thirty
 203 decrement ThirtyTwo = ThirtyOne