src/Text/Pandoc/UUID.hs · typeable/pandoc

git.iko.soy/typeable/pandoc

on f449dfd help sign in

typeable/pandoc/src/Text/Pandoc/UUID.hs

77 lines 2.3 kB history raw

1{-

4This program is free software; you can redistribute it and/or modify

5it under the terms of the GNU General Public License as published by

6the Free Software Foundation; either version 2 of the License, or

7(at your option) any later version.

9This program is distributed in the hope that it will be useful,

10but WITHOUT ANY WARRANTY; without even the implied warranty of

11MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

12GNU General Public License for more details.

14You should have received a copy of the GNU General Public License

15along with this program; if not, write to the Free Software

16Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

17-}

19{- |

20 Module : Text.Pandoc.UUID

22 License : GNU GPL, version 2 or above

24 Maintainer : John MacFarlane <jgm@berkeley.edu>

25 Stability : alpha

26 Portability : portable

28UUID generation using Version 4 (random method) described

29in RFC4122. See http://tools.ietf.org/html/rfc4122

30-}

32module Text.Pandoc.UUID ( UUID, getRandomUUID ) where

34import Text.Printf ( printf )

35import System.Random ( randomIO )

36import Data.Word

37import Data.Bits ( setBit, clearBit )

38import Control.Monad ( liftM )

40data UUID = UUID Word8 Word8 Word8 Word8 Word8 Word8 Word8 Word8

41 Word8 Word8 Word8 Word8 Word8 Word8 Word8 Word8

43instance Show UUID where

44 show (UUID a b c d e f g h i j k l m n o p) =

45 "urn:uuid:" ++

46 printf "%02x" a ++

47 printf "%02x" b ++

48 printf "%02x" c ++

49 printf "%02x" d ++

50 "-" ++

51 printf "%02x" e ++

52 printf "%02x" f ++

53 "-" ++

54 printf "%02x" g ++

55 printf "%02x" h ++

56 "-" ++

57 printf "%02x" i ++

58 printf "%02x" j ++

59 "-" ++

60 printf "%02x" k ++

61 printf "%02x" l ++

62 printf "%02x" m ++

63 printf "%02x" n ++

64 printf "%02x" o ++

65 printf "%02x" p

67getRandomUUID :: IO UUID

68getRandomUUID = do

69 let getRN :: a -> IO Word8

70 getRN _ = liftM fromIntegral (randomIO :: IO Int)

71 [a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p] <- mapM getRN ([1..16] :: [Int])

72 -- set variant

73 let i' = i `setBit` 7 `clearBit` 6

74 -- set version (0100 for random)

75 let g' = g `clearBit` 7 `setBit` 6 `clearBit` 5 `clearBit` 4

76 return $ UUID a b c d e f g' h i' j k l m n o p