Data/Time/RFC822.hs

   1 module Data.Time.RFC822
   2     ( format
   3     , parse
   4
   5     -- private
   6     , showRFC822TimeZone
   7     )
   8     where
   9
  10 import qualified Text.Parsec as P
  11
  12 import Data.Time
  13 import Data.Time.Calendar.WeekDate
  14 import Data.Time.HTTP.Common
  15 import Data.Time.RFC822.Parsec
  16
  17
  18 {-
  19      date-time   =  [ day "," ] date time        ; dd mm yy
  20                                                  ;  hh:mm:ss zzz
  21
  22      day         =  "Mon"  / "Tue" /  "Wed"  / "Thu"
  23                  /  "Fri"  / "Sat" /  "Sun"
  24
  25      date        =  1*2DIGIT month 2DIGIT        ; day month year
  26                                                  ;  e.g. 20 Jun 82
  27
  28      month       =  "Jan"  /  "Feb" /  "Mar"  /  "Apr"
  29                  /  "May"  /  "Jun" /  "Jul"  /  "Aug"
  30                  /  "Sep"  /  "Oct" /  "Nov"  /  "Dec"
  31
  32      time        =  hour zone                    ; ANSI and Military
  33
  34      hour        =  2DIGIT ":" 2DIGIT [":" 2DIGIT]
  35                                                  ; 00:00:00 - 23:59:59
  36
  37      zone        =  "UT"  / "GMT"                ; Universal Time
  38                                                  ; North American : UT
  39                  /  "EST" / "EDT"                ;  Eastern:  - 5/ - 4
  40                  /  "CST" / "CDT"                ;  Central:  - 6/ - 5
  41                  /  "MST" / "MDT"                ;  Mountain: - 7/ - 6
  42                  /  "PST" / "PDT"                ;  Pacific:  - 8/ - 7
  43                  /  1ALPHA                       ; Military: Z = UT;
  44                                                  ;  A:-1; (J not used)
  45                                                  ;  M:-12; N:+1; Y:+12
  46                  / ( ("+" / "-") 4DIGIT )        ; Local differential
  47                                                  ;  hours+min. (HHMM)
  48 -}
  49
  50 format :: ZonedTime -> String
  51 format zonedTime
  52     = let localTime          = zonedTimeToLocalTime zonedTime
  53           timeZone           = zonedTimeZone zonedTime
  54           (year, month, day) = toGregorian (localDay localTime)
  55           (_, _, week)       = toWeekDate  (localDay localTime)
  56           timeOfDay          = localTimeOfDay localTime
  57       in
  58         concat [ shortWeekDayName week
  59                , ", "
  60                , show2 day
  61                , " "
  62                , shortMonthName month
  63                , " "
  64                , show2 (year `mod` 100)
  65                , " "
  66                , show2 (todHour timeOfDay)
  67                , ":"
  68                , show2 (todMin timeOfDay)
  69                , ":"
  70                , show2 (floor (todSec timeOfDay))
  71                , " "
  72                , showRFC822TimeZone timeZone
  73                ]
  74
  75 showRFC822TimeZone :: TimeZone -> String
  76 showRFC822TimeZone tz
  77     | timeZoneMinutes tz == 0 = "GMT"
  78     | otherwise               = show4digitsTZ tz
  79
  80 parse :: String -> Maybe ZonedTime
  81 parse src = case P.parse p "" src of
  82               Right zt -> Just zt
  83               Left  _  -> Nothing
  84     where
  85       p = do zt <- rfc822DateAndTime
  86              _  <- P.eof
  87              return zt