1 -- |This module provides functions to parse and format RFC 822 date
4 -- The syntax is as follows:
6 -- > date-time ::= [ day-of-week ", " ] date SP time SP zone
7 -- > day-of-week ::= "Mon" | "Tue" | "Wed" | "Thu"
8 -- > | "Fri" | "Sat" | "Sun"
9 -- > date ::= day SP month SP year
11 -- > year ::= 2DIGIT ; Yes, only 2 digits.
12 -- > month ::= "Jan" | "Feb" | "Mar" | "Apr"
13 -- > | "May" | "Jun" | "Jul" | "Aug"
14 -- > | "Sep" | "Oct" | "Nov" | "Dec"
15 -- > time ::= hour ":" minute [ ":" second ]
17 -- > minute ::= 2DIGIT
18 -- > second ::= 2DIGIT
19 -- > zone ::= "UT" | "GMT" ; Universal Time
20 -- > | "EST" | "EDT" ; Eastern : -5 / -4
21 -- > | "CST" | "CDT" ; Central : -6 / -5
22 -- > | "MST" | "MDT" ; Mountain: -7 / -6
23 -- > | "PST" | "PDT" ; Pacific : -8 / -7
29 -- > | ("+" | "-") 4DIGIT ; Local diff: HHMM
30 module Data.Time.RFC822
39 import Data.Time.Calendar.WeekDate
40 import Data.Time.HTTP.Common
41 import Data.Time.RFC822.Internal
43 -- |Format a 'ZonedTime' in RFC 822.
44 format :: ZonedTime -> String
46 = let localTime = zonedTimeToLocalTime zonedTime
47 timeZone = zonedTimeZone zonedTime
48 (year, month, day) = toGregorian (localDay localTime)
49 (_, _, week) = toWeekDate (localDay localTime)
50 timeOfDay = localTimeOfDay localTime
52 concat [ shortWeekDayName week
56 , shortMonthName month
58 , show2 (year `mod` 100)
60 , show2 (todHour timeOfDay)
62 , show2 (todMin timeOfDay)
64 , show2 (floor (todSec timeOfDay))
66 , showRFC822TimeZone timeZone
70 showRFC822TimeZone :: TimeZone -> String
72 | timeZoneMinutes tz == 0 = "GMT"
73 | otherwise = show4digitsTZ tz
75 -- |Parse an RFC 822 date and time string. When the string can't be
76 -- parsed, it returns 'Nothing'.
77 parse :: String -> Maybe ZonedTime
78 parse src = case P.parse p "" src of
82 p = do zt <- rfc822DateAndTime