Finished docs

[time-http.git] / Data / Time / RFC822.hs

diff --git a/Data/Time/RFC822.hs b/Data/Time/RFC822.hs
index 72e3b28f2634b2ce39416b35d3b70b19244b4cd3..4c8e333d6f294d2435a6a2db46338ec16e969001 100644 (file)
--- a/Data/Time/RFC822.hs
+++ b/Data/Time/RFC822.hs
@@ -1,4 +1,88 @@
+{-# OPTIONS_HADDOCK prune #-}
+
+-- |This module provides functions to parse and format RFC 822 date
+-- and time formats.
+--
+-- The syntax is as follows:
+--
+-- > date-time   ::= [ day-of-week ", " ] date SP time SP zone
+-- > day-of-week ::= "Mon" | "Tue" | "Wed" | "Thu"
+-- >               | "Fri" | "Sat" | "Sun"
+-- > date        ::= day SP month SP year
+-- > day         ::= 2DIGIT
+-- > year        ::= 2DIGIT             ; Yes, only 2 digits.
+-- > month       ::= "Jan" | "Feb" | "Mar" | "Apr"
+-- >               | "May" | "Jun" | "Jul" | "Aug"
+-- >               | "Sep" | "Oct" | "Nov" | "Dec"
+-- > time        ::= hour ":" minute [ ":" second ]
+-- > hour        ::= 2DIGIT
+-- > minute      ::= 2DIGIT
+-- > second      ::= 2DIGIT
+-- > zone        ::= "UT"  | "GMT"      ; Universal Time
+-- >               | "EST" | "EDT"      ; Eastern : -5 / -4
+-- >               | "CST" | "CDT"      ; Central : -6 / -5
+-- >               | "MST" | "MDT"      ; Mountain: -7 / -6
+-- >               | "PST" | "PDT"      ; Pacific : -8 / -7
+-- >               | "Z"                ; UT
+-- >               | "A"                ;  -1
+-- >               | "M"                ; -12
+-- >               | "N"                ;  +1
+-- >               | "Y"                ; +12
+-- >               | ("+" | "-") 4DIGIT ; Local diff: HHMM
 module Data.Time.RFC822
-    (
+    ( format
+    , parse
+
+    -- private
+    , showRFC822TimeZone
     )
     where
+
+import qualified Text.Parsec as P
+
+import Data.Time
+import Data.Time.Calendar.WeekDate
+import Data.Time.HTTP.Common
+import Data.Time.RFC822.Parsec
+
+-- |Format a 'ZonedTime' in RFC 822.
+format :: ZonedTime -> String
+format zonedTime
+    = let localTime          = zonedTimeToLocalTime zonedTime
+          timeZone           = zonedTimeZone zonedTime
+          (year, month, day) = toGregorian (localDay localTime)
+          (_, _, week)       = toWeekDate  (localDay localTime)
+          timeOfDay          = localTimeOfDay localTime
+      in
+        concat [ shortWeekDayName week
+               , ", "
+               , show2 day
+               , " "
+               , shortMonthName month
+               , " "
+               , show2 (year `mod` 100)
+               , " "
+               , show2 (todHour timeOfDay)
+               , ":"
+               , show2 (todMin timeOfDay)
+               , ":"
+               , show2 (floor (todSec timeOfDay))
+               , " "
+               , showRFC822TimeZone timeZone
+               ]
+
+showRFC822TimeZone :: TimeZone -> String
+showRFC822TimeZone tz
+    | timeZoneMinutes tz == 0 = "GMT"
+    | otherwise               = show4digitsTZ tz
+
+-- |Parse an RFC 822 date and time string. When the string can't be
+-- parsed, it returns 'Nothing'.
+parse :: String -> Maybe ZonedTime
+parse src = case P.parse p "" src of
+              Right zt -> Just zt
+              Left  _  -> Nothing
+    where
+      p = do zt <- rfc822DateAndTime
+             _  <- P.eof
+             return zt