Data/Time/RFC733.hs

   1 module Data.Time.RFC733
   2     ( format
   3     , parse
   4     )
   5     where
   6
   7 import qualified Text.Parsec as P
   8
   9 import Data.Time
  10 import Data.Time.Calendar.WeekDate
  11 import Data.Time.HTTP.Common
  12 import Data.Time.RFC733.Parsec
  13
  14 {-
  15 date-time   =  [ day-of-week "," ] date time
  16
  17 day-of-week =  "Monday"    / "Mon"  / "Tuesday"   / "Tue"
  18             /  "Wednesday" / "Wed"  / "Thursday"  / "Thu"
  19             /  "Friday"    / "Fri"  / "Saturday"  / "Sat"
  20             /  "Sunday"    / "Sun"
  21
  22 date        =  1*2DIGIT ["-"] month         ; day month year
  23                ["-"] (2DIGIT /4DIGIT)       ;  e.g. 20 Aug [19]77
  24
  25 month       =  "January"   / "Jan"  / "February"  / "Feb"
  26             /  "March"     / "Mar"  / "April"     / "Apr"
  27             /  "May"                / "June"      / "Jun"
  28             /  "July"      / "Jul"  / "August"    / "Aug"
  29             /  "September" / "Sep"  / "October"   / "Oct"
  30             /  "November"  / "Nov"  / "December"  / "Dec"
  31
  32 time        =  hour zone                    ; ANSI and Military
  33                                             ;  (seconds optional)
  34
  35 hour        =  2DIGIT [":"] 2DIGIT [ [":"] 2DIGIT ]
  36                                             ; 0000[00] - 2359[59]
  37
  38 zone        = ( ["-"] ( "GMT"               ; Relative to GMT:
  39                                             ; North American
  40                  /  "NST" /                 ;  Newfoundland:-3:30
  41                  /  "AST" / "ADT"           ;  Atlantic: - 4/ - 3
  42                  /  "EST" / "EDT"           ;  Eastern:  - 5/ - 4
  43                  /  "CST" / "CDT"           ;  Central:  - 6/ - 5
  44                  /  "MST" / "MDT"           ;  Mountain: - 7/ - 6
  45                  /  "PST" / "PDT"           ;  Pacific:  - 8/ - 7
  46                  /  "YST" / "YDT"           ;  Yukon:    - 9/ - 8
  47                  /  "HST" / "HDT"           ;  Haw/Ala   -10/ - 9
  48                  /  "BST" / "BDT"           ;  Bering:   -11/ -10
  49                     1ALPHA       ))         ; Military: Z = GMT;
  50                                             ;  A:-1; (J not used)
  51                                             ;  M:-12; N:+1; Y:+12
  52             / ( ("+" / "-") 4DIGIT )        ; Local differential
  53                                             ;  hours/min. (HHMM)
  54 -}
  55
  56 format :: ZonedTime -> String
  57 format zonedTime
  58     = let localTime          = zonedTimeToLocalTime zonedTime
  59           timeZone           = zonedTimeZone zonedTime
  60           (year, month, day) = toGregorian (localDay localTime)
  61           (_, _, week)       = toWeekDate  (localDay localTime)
  62           timeOfDay          = localTimeOfDay localTime
  63       in
  64         concat [ longWeekDayName week
  65                , ", "
  66                , show2 day
  67                , "-"
  68                , shortMonthName month
  69                , "-"
  70                , show4 year
  71                , " "
  72                , show2 (todHour timeOfDay)
  73                , ":"
  74                , show2 (todMin timeOfDay)
  75                , ":"
  76                , show2 (floor (todSec timeOfDay))
  77                , " "
  78                , show4digitsTZ timeZone
  79                ]
  80
  81 parse :: String -> Maybe ZonedTime
  82 parse src = case P.parse p "" src of
  83               Right zt -> Just zt
  84               Left  _  -> Nothing
  85     where
  86       p = do zt <- parser
  87              _  <- P.eof
  88              return zt