1 {-# OPTIONS_HADDOCK prune #-}
3 -- |This module provides functions to parse and format RFC 822 date
6 -- The syntax is as follows:
8 -- > date-time ::= [ day-of-week ", " ] date SP time SP zone
9 -- > day-of-week ::= "Mon" | "Tue" | "Wed" | "Thu"
10 -- > | "Fri" | "Sat" | "Sun"
11 -- > date ::= day SP month SP year
13 -- > year ::= 2DIGIT ; Yes, only 2 digits.
14 -- > month ::= "Jan" | "Feb" | "Mar" | "Apr"
15 -- > | "May" | "Jun" | "Jul" | "Aug"
16 -- > | "Sep" | "Oct" | "Nov" | "Dec"
17 -- > time ::= hour ":" minute [ ":" second ]
19 -- > minute ::= 2DIGIT
20 -- > second ::= 2DIGIT
21 -- > zone ::= "UT" | "GMT" ; Universal Time
22 -- > | "EST" | "EDT" ; Eastern : -5 / -4
23 -- > | "CST" | "CDT" ; Central : -6 / -5
24 -- > | "MST" | "MDT" ; Mountain: -7 / -6
25 -- > | "PST" | "PDT" ; Pacific : -8 / -7
31 -- > | ("+" | "-") 4DIGIT ; Local diff: HHMM
32 module Data.Time.RFC822
41 import qualified Text.Parsec as P
44 import Data.Time.Calendar.WeekDate
45 import Data.Time.HTTP.Common
46 import Data.Time.RFC822.Parsec
48 -- |Format a 'ZonedTime' in RFC 822.
49 format :: ZonedTime -> String
51 = let localTime = zonedTimeToLocalTime zonedTime
52 timeZone = zonedTimeZone zonedTime
53 (year, month, day) = toGregorian (localDay localTime)
54 (_, _, week) = toWeekDate (localDay localTime)
55 timeOfDay = localTimeOfDay localTime
57 concat [ shortWeekDayName week
61 , shortMonthName month
63 , show2 (year `mod` 100)
65 , show2 (todHour timeOfDay)
67 , show2 (todMin timeOfDay)
69 , show2 (floor (todSec timeOfDay))
71 , showRFC822TimeZone timeZone
74 showRFC822TimeZone :: TimeZone -> String
76 | timeZoneMinutes tz == 0 = "GMT"
77 | otherwise = show4digitsTZ tz
79 -- |Parse an RFC 822 date and time string. When the string can't be
80 -- parsed, it returns 'Nothing'.
81 parse :: String -> Maybe ZonedTime
82 parse src = case P.parse p "" src of
86 p = do zt <- rfc822DateAndTime