+{-# LANGUAGE FlexibleContexts #-}
+module Data.Time.RFC733.Parsec
+ ( parser
+ )
+ where
+
+import Control.Monad
+import Data.Fixed
+import Data.Time
+import Data.Time.Calendar.WeekDate
+import Data.Time.HTTP.Common
+import Text.Parsec
+
+
+parser :: Stream s m Char => ParsecT s u m ZonedTime
+parser = dateTime
+
+dateTime :: Stream s m Char => ParsecT s u m ZonedTime
+dateTime = do weekDay <- optionMaybe $
+ do w <- try longWeekDayNameP
+ <|>
+ shortWeekDayNameP
+ _ <- string ", "
+ return w
+ gregDay <- date
+ case weekDay of
+ Nothing
+ -> return ()
+ Just givenWD
+ -> assertWeekDayIsGood givenWD gregDay
+ (tod, timeZone) <- time
+ let lt = LocalTime gregDay tod
+ zt = ZonedTime lt timeZone
+ return zt
+
+date :: Stream s m Char => ParsecT s u m Day
+date = do day <- read2
+ _ <- char '-' <|> char ' '
+ month <- try longMonthNameP
+ <|>
+ shortMonthNameP
+ _ <- char '-' <|> char ' '
+ year <- try read4
+ <|>
+ liftM (+ 1900) read2
+ _ <- char ' '
+ assertGregorianDateIsGood (toInteger year) month day
+
+time :: Stream s m Char => ParsecT s u m (TimeOfDay, TimeZone)
+time = do tod <- hour
+ _ <- char ' '
+ tz <- zone
+ return (tod, tz)
+
+hour :: Stream s m Char => ParsecT s u m TimeOfDay
+hour = do hour <- read2
+ _ <- optional (char ':')
+ minute <- read2
+ second <- option 0 $
+ do _ <- optional (char ':')
+ read2
+ assertTimeOfDayIsGood hour minute second
+
+zone :: Stream s m Char => ParsecT s u m TimeZone
+zone = choice [ string "GMT" >> return (TimeZone 0 False "GMT")
+ , char 'N'
+ >> choice [ string "ST" >> return (TimeZone ((-3) * 60 - 30) False "NST")
+ , return (TimeZone (1 * 60) False "N")
+ ]
+ , char 'A'
+ >> choice [ string "ST" >> return (TimeZone ((-4) * 60) False "AST")
+ , string "DT" >> return (TimeZone ((-3) * 60) False "AST")
+ , return (TimeZone ((-1) * 60) False "A")
+ ]
+ , char 'E'
+ >> choice [ string "ST" >> return (TimeZone ((-5) * 60) False "EST")
+ , string "DT" >> return (TimeZone ((-4) * 60) True "EDT")
+ ]
+ , char 'C'
+ >> choice [ string "ST" >> return (TimeZone ((-6) * 60) False "CST")
+ , string "DT" >> return (TimeZone ((-5) * 60) True "CDT")
+ ]
+ , char 'M'
+ >> choice [ string "ST" >> return (TimeZone ((-7) * 60) False "MST")
+ , string "DT" >> return (TimeZone ((-6) * 60) True "MDT")
+ , return (TimeZone ((-12) * 60) False "M")
+ ]
+ , char 'P'
+ >> choice [ string "ST" >> return (TimeZone ((-8) * 60) False "PST")
+ , string "DT" >> return (TimeZone ((-7) * 60) True "PDT")
+ ]
+ , char 'Y'
+ >> choice [ string "ST" >> return (TimeZone ((-9) * 60) False "YST")
+ , string "DT" >> return (TimeZone ((-8) * 60) True "YDT")
+ , return (TimeZone ( 12 * 60) False "Y")
+ ]
+ , char 'H'
+ >> choice [ string "ST" >> return (TimeZone ((-10) * 60) False "HST")
+ , string "DT" >> return (TimeZone (( -9) * 60) True "HDT")
+ ]
+ , char 'B'
+ >> choice [ string "ST" >> return (TimeZone ((-11) * 60) False "BST")
+ , string "DT" >> return (TimeZone ((-10) * 60) True "BDT")
+ ]
+ , char 'Z' >> return (TimeZone 0 False "Z")
+ , read4digitsTZ
+ ]