Rewrote RFC733

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

diff --git a/Data/Time/Asctime.hs b/Data/Time/Asctime.hs
index 0da530571a329787d82c91136f668b457f51febf..f8d28ccd80091fb0424c779245aaa6627d50068a 100644 (file)
--- a/Data/Time/Asctime.hs
+++ b/Data/Time/Asctime.hs
@@ -1,65 +1,108 @@
--- |This module is for ANSI C's asctime() format.
+{-# LANGUAGE
+    FlexibleInstances
+  , MultiParamTypeClasses
+  , OverloadedStrings
+  , TemplateHaskell
+  , UnicodeSyntax
+  #-}
+-- |This module provides functions for ANSI C's asctime() format.
 --
 -- ANSI C's asctime() format looks like:
 --
--- @Wdy Mon DD HH:MM:SS YYYY@
+-- @Wdy Mon [D]D HH:MM:SS YYYY@
 --
 -- The exact syntax is as follows:
 --
--- > date-time ::= wday ' ' month ' ' day ' ' time ' ' year
+-- > date-time ::= wday SP month SP day SP time SP year
 -- > wday      ::= "Mon" | "Tue" | "Wed" | "Thu"
 -- >             | "Fri" | "Sat" | "Sun"
 -- > month     ::= "Jan" | "Feb" | "Mar" | "Apr"
 -- >             | "May" | "Jun" | "Jul" | "Aug"
 -- >             | "Sep" | "Oct" | "Nov" | "Dec"
--- > day       ::= 2DIGIT
+-- > day       ::= 2DIGIT | SP 1DIGIT
 -- > time      ::= 2DIGIT ':' 2DIGIT [':' 2DIGIT]
 -- > year      ::= 4DIGIT
 --
 -- As you can see, it has no time zone info. "Data.Time.HTTP" will
 -- treat it as UTC.
 module Data.Time.Asctime
-    ( format
-    , parse
+    ( Asctime
+    , asctime
     )
     where
-
-import qualified Text.Parsec as P
-
+import Control.Applicative
+import Data.Ascii (Ascii, AsciiBuilder)
+import qualified Data.Ascii as A
+import Data.Attoparsec.Char8
+import Data.Convertible.Base
+import Data.Monoid.Unicode
+import Data.Tagged
 import Data.Time
 import Data.Time.Calendar.WeekDate
 import Data.Time.HTTP.Common
-import Data.Time.Asctime.Parsec
+import Prelude.Unicode
+
+-- |The phantom type for conversion between ANSI C's @asctime()@
+-- string and 'LocalTime'.
+--
+-- >>> convertSuccess (LocalTime (ModifiedJulianDay 49662) (TimeOfDay 8 49 37))
+-- Tagged "Sun Nov  6 08:49:37 1994"
+data Asctime
+
+instance ConvertSuccess LocalTime (Tagged Asctime Ascii) where
+    {-# INLINE convertSuccess #-}
+    convertSuccess = (A.fromAsciiBuilder <$>) ∘ cs
+
+instance ConvertSuccess LocalTime (Tagged Asctime AsciiBuilder) where
+    {-# INLINE convertSuccess #-}
+    convertSuccess = Tagged ∘ toAsciiBuilder
+
+instance ConvertAttempt (Tagged Asctime Ascii) LocalTime where
+    {-# INLINE convertAttempt #-}
+    convertAttempt = parseAttempt' asctime ∘ untag
 
--- |Format a 'LocalTime' in the ANSI C's asctime() way.
-format :: LocalTime -> String
-format localTime
+-- |Parse an ANSI C's @asctime()@ string.
+asctime ∷ Parser LocalTime
+asctime = do weekDay ← shortWeekDayNameP
+             _       ← char ' '
+             month   ← shortMonthNameP
+             _       ← char ' '
+             day     ← read2'
+             _       ← char ' '
+             hour    ← read2
+             _       ← char ':'
+             minute  ← read2
+             _       ← char ':'
+             second  ← read2
+             _       ← char ' '
+             year    ← read4
+
+             gregDay ← assertGregorianDateIsGood year month day
+             _       ← assertWeekDayIsGood weekDay gregDay
+             tod     ← assertTimeOfDayIsGood hour minute second
+
+             return (LocalTime gregDay tod)
+
+toAsciiBuilder ∷ LocalTime → AsciiBuilder
+toAsciiBuilder localTime
     = let (year, month, day) = toGregorian (localDay localTime)
           (_, _, week)       = toWeekDate  (localDay localTime)
           timeOfDay          = localTimeOfDay localTime
       in
-        concat [ shortWeekDayName week
-               , ", "
-               , shortMonthName month
-               , " "
-               , show2 day
-               , " "
-               , show2 (todHour timeOfDay)
-               , ":"
-               , show2 (todMin timeOfDay)
-               , ":"
-               , show2 (floor (todSec timeOfDay))
-               , " "
-               , show4 year
-               ]
+        shortWeekDayName week
+        ⊕ A.toAsciiBuilder " "
+        ⊕ shortMonthName month
+        ⊕ A.toAsciiBuilder " "
+        ⊕ show2' day
+        ⊕ A.toAsciiBuilder " "
+        ⊕ show2 (todHour timeOfDay)
+        ⊕ A.toAsciiBuilder ":"
+        ⊕ show2 (todMin timeOfDay)
+        ⊕ A.toAsciiBuilder ":"
+        ⊕ show2 (floor (todSec timeOfDay) ∷ Int)
+        ⊕ A.toAsciiBuilder " "
+        ⊕ show4 year
 
--- |Parse an ANSI C's asctime() format to 'LocalTime'. When the string
--- can't be parsed, it returns 'Nothing'.
-parse :: String -> Maybe LocalTime
-parse src = case P.parse p "" src of
-              Right zt -> Just zt
-              Left  _  -> Nothing
-    where
-      p = do zt <- asctime
-             _  <- P.eof
-             return zt
+deriveAttempts [ ([t| LocalTime |], [t| Tagged Asctime Ascii        |])
+               , ([t| LocalTime |], [t| Tagged Asctime AsciiBuilder |])
+               ]