+{-# 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 Data.Time.HTTP.Common
import Data.Time.RFC822.Parsec
-
-{-
- date-time = [ day "," ] date time ; dd mm yy
- ; hh:mm:ss zzz
-
- day = "Mon" / "Tue" / "Wed" / "Thu"
- / "Fri" / "Sat" / "Sun"
-
- date = 1*2DIGIT month 2DIGIT ; day month year
- ; e.g. 20 Jun 82
-
- month = "Jan" / "Feb" / "Mar" / "Apr"
- / "May" / "Jun" / "Jul" / "Aug"
- / "Sep" / "Oct" / "Nov" / "Dec"
-
- time = hour zone ; ANSI and Military
-
- hour = 2DIGIT ":" 2DIGIT [":" 2DIGIT]
- ; 00:00:00 - 23:59:59
-
- zone = "UT" / "GMT" ; Universal Time
- ; North American : UT
- / "EST" / "EDT" ; Eastern: - 5/ - 4
- / "CST" / "CDT" ; Central: - 6/ - 5
- / "MST" / "MDT" ; Mountain: - 7/ - 6
- / "PST" / "PDT" ; Pacific: - 8/ - 7
- / 1ALPHA ; Military: Z = UT;
- ; A:-1; (J not used)
- ; M:-12; N:+1; Y:+12
- / ( ("+" / "-") 4DIGIT ) ; Local differential
- ; hours+min. (HHMM)
--}
-
+-- |Format a 'ZonedTime' in RFC 822.
format :: ZonedTime -> String
format zonedTime
= let localTime = zonedTimeToLocalTime zonedTime
, ":"
, show2 (floor (todSec timeOfDay))
, " "
- , show4digitsTZ timeZone
+ , 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 <- parser
+ p = do zt <- rfc822DateAndTime
_ <- P.eof
return zt