1 -----------------------------------------------------------------------------
3 -- Module : System.Time
4 -- Copyright : (c) The University of Glasgow 2001
5 -- License : BSD-style (see the file libraries/core/LICENSE)
7 -- Maintainer : libraries@haskell.org
8 -- Stability : provisional
9 -- Portability : portable
11 -- The standard Time library.
13 -----------------------------------------------------------------------------
16 Haskell 98 Time of Day Library
17 ------------------------------
19 The Time library provides standard functionality for clock times,
20 including timezone information (i.e, the functionality of "time.h",
21 adapted to the Haskell environment), It follows RFC 1129 in its use of
22 Coordinated Universal Time (UTC).
24 2000/06/17 <michael.weber@post.rwth-aachen.de>:
26 * min./max. time diff currently is restricted to
27 [minBound::Int, maxBound::Int]
29 * surely other restrictions wrt. min/max bounds
35 `showTime' (used in `instance Show ClockTime') always prints time
36 converted to the local timezone (even if it is taken from
37 `(toClockTime . toUTCTime)'), whereas `calendarTimeToString'
38 honors the tzone & tz fields and prints UTC or whatever timezone
39 is stored inside CalendarTime.
41 Maybe `showTime' should be changed to use UTC, since it would
42 better correspond to the actual representation of `ClockTime'
43 (can be done by replacing localtime(3) by gmtime(3)).
47 * add proper handling of microsecs, currently, they're mostly
50 * `formatFOO' case of `%s' is currently broken...
54 * check for unusual date cases, like 1970/1/1 00:00h, and conversions
55 between different timezone's etc.
57 * check, what needs to be in the IO monad, the current situation
58 seems to be a bit inconsistent to me
60 * check whether `isDst = -1' works as expected on other arch's
63 * add functions to parse strings to `CalendarTime' (some day...)
65 * implement padding capabilities ("%_", "%-") in `formatFOO'
67 * add rfc822 timezone (+0200 is CEST) representation ("%z") in `formatFOO'
75 , ClockTime(..) -- non-standard, lib. report gives this as abstract
77 -- instance Show (non-standard)
82 , noTimeDiff -- non-standard (but useful when constructing TimeDiff vals.)
86 , normalizeTimeDiff -- non-standard
87 , timeDiffToString -- non-standard
88 , formatTimeDiff -- non-standard
94 , calendarTimeToString
105 import System.IO.Unsafe
110 -- One way to partition and give name to chunks of a year and a week:
113 = January | February | March | April
114 | May | June | July | August
115 | September | October | November | December
116 deriving (Eq, Ord, Enum, Bounded, Ix, Read, Show)
119 = Sunday | Monday | Tuesday | Wednesday
120 | Thursday | Friday | Saturday
121 deriving (Eq, Ord, Enum, Bounded, Ix, Read, Show)
123 -- @ClockTime@ is an abstract type, used for the internal clock time.
124 -- Clock times may be compared, converted to strings, or converted to an
125 -- external calendar time @CalendarTime@.
127 data ClockTime = TOD Integer -- Seconds since 00:00:00 on 1 Jan 1970
128 Integer -- Picoseconds with the specified second
131 -- When a ClockTime is shown, it is converted to a CalendarTime in the current
132 -- timezone and then printed. FIXME: This is arguably wrong, since we can't
133 -- get the current timezone without being in the IO monad.
135 instance Show ClockTime where
136 showsPrec _ t = showString (calendarTimeToString
137 (unsafePerformIO (toCalendarTime t)))
140 @CalendarTime@ is a user-readable and manipulable
141 representation of the internal $ClockTime$ type. The
142 numeric fields have the following ranges.
148 year -maxInt .. maxInt [Pre-Gregorian dates are inaccurate]
149 mon 0 .. 11 [Jan = 0, Dec = 11]
153 sec 0 .. 61 [Allows for two leap seconds]
154 picosec 0 .. (10^12)-1 [This could be over-precise?]
155 wday 0 .. 6 [Sunday = 0, Saturday = 6]
156 yday 0 .. 365 [364 in non-Leap years]
157 tz -43200 .. 43200 [Variation from UTC in seconds]
160 The {\em tzname} field is the name of the time zone. The {\em isdst}
161 field indicates whether Daylight Savings Time would be in effect.
172 ctPicosec :: Integer,
179 deriving (Eq,Ord,Read,Show)
181 -- The @TimeDiff@ type records the difference between two clock times in
182 -- a user-readable way.
192 tdPicosec :: Integer -- not standard
194 deriving (Eq,Ord,Read,Show)
196 noTimeDiff :: TimeDiff
197 noTimeDiff = TimeDiff 0 0 0 0 0 0 0
199 -- -----------------------------------------------------------------------------
200 -- getClockTime returns the current time in its internal representation.
202 getClockTime :: IO ClockTime
203 #if HAVE_GETTIMEOFDAY
205 allocaBytes (#const sizeof(struct timeval)) $ \ p_timeval -> do
206 throwErrnoIfMinus1_ "getClockTime" $ gettimeofday p_timeval nullPtr
207 sec <- (#peek struct timeval,tv_sec) p_timeval :: IO CTime
208 usec <- (#peek struct timeval,tv_usec) p_timeval :: IO CTime
209 return (TOD (fromIntegral sec) ((fromIntegral usec) * 1000000))
213 allocaBytes (#const sizeof(struct timeb)) $ \ p_timeb -> do
215 sec <- (#peek struct timeb,time) p_timeb :: IO CTime
216 msec <- (#peek struct timeb,millitm) p_timeb :: IO CUShort
217 return (TOD (fromIntegral sec) (fromIntegral msec * 1000000000))
219 #else /* use POSIX time() */
221 secs <- time nullPtr -- can't fail, according to POSIX
222 return (TOD (fromIntegral secs) 0)
226 -- -----------------------------------------------------------------------------
227 -- addToClockTime d t adds a time difference d and a
228 -- clock time t to yield a new clock time. The difference d
229 -- may be either positive or negative. diffClockTimes t1 t2 returns
230 -- the difference between two clock times t1 and t2 as a TimeDiff.
232 addToClockTime :: TimeDiff -> ClockTime -> ClockTime
233 addToClockTime (TimeDiff year mon day hour min sec psec)
236 sec_diff = toInteger sec +
238 3600 * toInteger hour +
239 24 * 3600 * toInteger day
240 cal = toUTCTime (TOD (c_sec + sec_diff) (c_psec + psec))
242 new_mon = fromEnum (ctMonth cal) + r_mon
244 | new_mon < 0 = (toEnum (12 + new_mon), (-1))
245 | new_mon > 11 = (toEnum (new_mon `mod` 12), 1)
246 | otherwise = (toEnum new_mon, 0)
248 (r_yr, r_mon) = mon `quotRem` 12
250 year' = ctYear cal + year + r_yr + yr_diff
252 toClockTime cal{ctMonth=month', ctYear=year'}
254 diffClockTimes :: ClockTime -> ClockTime -> TimeDiff
255 -- diffClockTimes is meant to be the dual to `addToClockTime'.
256 -- If you want to have the TimeDiff properly splitted, use
257 -- `normalizeTimeDiff' on this function's result
259 -- CAVEAT: see comment of normalizeTimeDiff
260 diffClockTimes (TOD sa pa) (TOD sb pb) =
261 noTimeDiff{ tdSec = fromIntegral (sa - sb)
262 -- FIXME: can handle just 68 years...
263 , tdPicosec = pa - pb
267 normalizeTimeDiff :: TimeDiff -> TimeDiff
268 -- FIXME: handle psecs properly
269 -- FIXME: ?should be called by formatTimeDiff automagically?
271 -- when applied to something coming out of `diffClockTimes', you loose
272 -- the duality to `addToClockTime', since a year does not always have
275 -- apply this function as late as possible to prevent those "rounding"
277 normalizeTimeDiff td =
284 + 365 * tdYear td))))
286 (diffYears, rest1) = rest0 `quotRem` (365 * 24 * 3600)
287 (diffMonths, rest2) = rest1 `quotRem` (30 * 24 * 3600)
288 (diffDays, rest3) = rest2 `quotRem` (24 * 3600)
289 (diffHours, rest4) = rest3 `quotRem` 3600
290 (diffMins, diffSecs) = rest4 `quotRem` 60
292 td{ tdYear = diffYears
293 , tdMonth = diffMonths
300 -- -----------------------------------------------------------------------------
301 -- How do we deal with timezones on this architecture?
303 -- The POSIX way to do it is through the global variable tzname[].
304 -- But that's crap, so we do it The BSD Way if we can: namely use the
305 -- tm_zone and tm_gmtoff fields of struct tm, if they're available.
307 zone :: Ptr CTm -> IO (Ptr CChar)
308 gmtoff :: Ptr CTm -> IO CLong
310 zone x = (#peek struct tm,tm_zone) x
311 gmtoff x = (#peek struct tm,tm_gmtoff) x
313 #else /* ! HAVE_TM_ZONE */
314 # if HAVE_TZNAME || defined(_WIN32)
315 # if cygwin32_TARGET_OS
316 # define tzname _tzname
318 # ifndef mingw32_TARGET_OS
319 foreign import ccall unsafe "&tzname" tzname :: Ptr (Ptr CChar)
321 foreign import ccall unsafe "__hscore_timezone" timezone :: Ptr CLong
322 foreign import ccall unsafe "__hscore_tzname" tzname :: Ptr (Ptr CChar)
325 dst <- (#peek struct tm,tm_isdst) x
326 if dst then peekElemOff tzname 1 else peekElemOff tzname 0
327 # else /* ! HAVE_TZNAME */
328 -- We're in trouble. If you should end up here, please report this as a bug.
329 # error "Don't know how to get at timezone name on your OS."
330 # endif /* ! HAVE_TZNAME */
332 -- Get the offset in secs from UTC, if (struct tm) doesn't supply it. */
334 foreign import ccall "&altzone" altzone :: Ptr CTime
335 foreign import ccall "&timezone" timezone :: Ptr CTime
337 dst <- (#peek struct tm,tm_isdst) x
338 tz <- if dst then peek altzone else peek timezone
339 return (-fromIntegral tz)
340 # else /* ! HAVE_ALTZONE */
342 #if !defined(mingw32_TARGET_OS)
343 foreign import ccall unsafe "timezone" timezone :: Ptr CLong
346 -- Assume that DST offset is 1 hour ...
348 dst <- (#peek struct tm,tm_isdst) x
350 -- According to the documentation for tzset(),
351 -- http://www.opengroup.org/onlinepubs/007908799/xsh/tzset.html
352 -- timezone offsets are > 0 west of the Prime Meridian.
354 -- This module assumes the interpretation of tm_gmtoff, i.e., offsets
355 -- are > 0 East of the Prime Meridian, so flip the sign.
356 return (- (if dst then (fromIntegral tz - 3600) else tz))
357 # endif /* ! HAVE_ALTZONE */
358 #endif /* ! HAVE_TM_ZONE */
360 -- -----------------------------------------------------------------------------
361 -- toCalendarTime t converts t to a local time, modified by
362 -- the current timezone and daylight savings time settings. toUTCTime
363 -- t converts t into UTC time. toClockTime l converts l into the
364 -- corresponding internal ClockTime. The wday, yday, tzname, and isdst fields
368 toCalendarTime :: ClockTime -> IO CalendarTime
370 toCalendarTime = clockToCalendarTime_reentrant (throwAwayReturnPointer localtime_r) False
372 toCalendarTime = clockToCalendarTime_static localtime False
375 toUTCTime :: ClockTime -> CalendarTime
377 toUTCTime = unsafePerformIO . clockToCalendarTime_reentrant (throwAwayReturnPointer gmtime_r) True
379 toUTCTime = unsafePerformIO . clockToCalendarTime_static gmtime True
382 throwAwayReturnPointer :: (Ptr CTime -> Ptr CTm -> IO (Ptr CTm))
383 -> (Ptr CTime -> Ptr CTm -> IO ( ))
384 throwAwayReturnPointer fun x y = fun x y >> return ()
386 clockToCalendarTime_static :: (Ptr CTime -> IO (Ptr CTm)) -> Bool -> ClockTime
388 clockToCalendarTime_static fun is_utc (TOD secs psec) = do
389 withObject (fromIntegral secs :: CTime) $ \ p_timer -> do
390 p_tm <- fun p_timer -- can't fail, according to POSIX
391 clockToCalendarTime_aux is_utc p_tm psec
393 clockToCalendarTime_reentrant :: (Ptr CTime -> Ptr CTm -> IO ()) -> Bool -> ClockTime
395 clockToCalendarTime_reentrant fun is_utc (TOD secs psec) = do
396 withObject (fromIntegral secs :: CTime) $ \ p_timer -> do
397 allocaBytes (#const sizeof(struct tm)) $ \ p_tm -> do
399 clockToCalendarTime_aux is_utc p_tm psec
401 clockToCalendarTime_aux :: Bool -> Ptr CTm -> Integer -> IO CalendarTime
402 clockToCalendarTime_aux is_utc p_tm psec = do
403 sec <- (#peek struct tm,tm_sec ) p_tm :: IO CInt
404 min <- (#peek struct tm,tm_min ) p_tm :: IO CInt
405 hour <- (#peek struct tm,tm_hour ) p_tm :: IO CInt
406 mday <- (#peek struct tm,tm_mday ) p_tm :: IO CInt
407 mon <- (#peek struct tm,tm_mon ) p_tm :: IO CInt
408 year <- (#peek struct tm,tm_year ) p_tm :: IO CInt
409 wday <- (#peek struct tm,tm_wday ) p_tm :: IO CInt
410 yday <- (#peek struct tm,tm_yday ) p_tm :: IO CInt
411 isdst <- (#peek struct tm,tm_isdst) p_tm :: IO CInt
415 tzname <- peekCString zone
417 let month | mon >= 0 && mon <= 11 = toEnum (fromIntegral mon)
418 | otherwise = error ("toCalendarTime: illegal month value: " ++ show mon)
421 (1900 + fromIntegral year)
428 (toEnum (fromIntegral wday))
430 (if is_utc then "UTC" else tzname)
431 (if is_utc then 0 else fromIntegral tz)
432 (if is_utc then False else isdst /= 0))
435 toClockTime :: CalendarTime -> ClockTime
436 toClockTime (CalendarTime year mon mday hour min sec psec
437 _wday _yday _tzname tz isdst) =
439 -- `isDst' causes the date to be wrong by one hour...
440 -- FIXME: check, whether this works on other arch's than Linux, too...
442 -- so we set it to (-1) (means `unknown') and let `mktime' determine
444 let isDst = -1 :: CInt in -- if isdst then (1::Int) else 0
446 if psec < 0 || psec > 999999999999 then
447 error "Time.toClockTime: picoseconds out of range"
448 else if tz < -43200 || tz > 43200 then
449 error "Time.toClockTime: timezone offset out of range"
452 allocaBytes (#const sizeof(struct tm)) $ \ p_tm -> do
453 (#poke struct tm,tm_sec ) p_tm (fromIntegral sec :: CInt)
454 (#poke struct tm,tm_min ) p_tm (fromIntegral min :: CInt)
455 (#poke struct tm,tm_hour ) p_tm (fromIntegral hour :: CInt)
456 (#poke struct tm,tm_mday ) p_tm (fromIntegral mday :: CInt)
457 (#poke struct tm,tm_mon ) p_tm (fromIntegral (fromEnum mon) :: CInt)
458 (#poke struct tm,tm_year ) p_tm (fromIntegral year - 1900 :: CInt)
459 (#poke struct tm,tm_isdst) p_tm isDst
460 t <- throwIf (== -1) (\_ -> "Time.toClockTime: invalid input")
463 -- mktime expects its argument to be in the local timezone, but
464 -- toUTCTime makes UTC-encoded CalendarTime's ...
466 -- Since there is no any_tz_struct_tm-to-time_t conversion
467 -- function, we have to fake one... :-) If not in all, it works in
468 -- most cases (before, it was the other way round...)
470 -- Luckily, mktime tells us, what it *thinks* the timezone is, so,
471 -- to compensate, we add the timezone difference to mktime's
474 gmtoff <- gmtoff p_tm
475 let res = fromIntegral t - tz + fromIntegral gmtoff
476 return (TOD (fromIntegral res) psec)
478 -- -----------------------------------------------------------------------------
479 -- Converting time values to strings.
481 calendarTimeToString :: CalendarTime -> String
482 calendarTimeToString = formatCalendarTime defaultTimeLocale "%c"
484 formatCalendarTime :: TimeLocale -> String -> CalendarTime -> String
485 formatCalendarTime l fmt (CalendarTime year mon day hour min sec _
486 wday yday tzname _ _) =
488 where doFmt ('%':'-':cs) = doFmt ('%':cs) -- padding not implemented
489 doFmt ('%':'_':cs) = doFmt ('%':cs) -- padding not implemented
490 doFmt ('%':c:cs) = decode c ++ doFmt cs
491 doFmt (c:cs) = c : doFmt cs
494 decode 'A' = fst (wDays l !! fromEnum wday) -- day of the week, full name
495 decode 'a' = snd (wDays l !! fromEnum wday) -- day of the week, abbrev.
496 decode 'B' = fst (months l !! fromEnum mon) -- month, full name
497 decode 'b' = snd (months l !! fromEnum mon) -- month, abbrev
498 decode 'h' = snd (months l !! fromEnum mon) -- ditto
499 decode 'C' = show2 (year `quot` 100) -- century
500 decode 'c' = doFmt (dateTimeFmt l) -- locale's data and time format.
501 decode 'D' = doFmt "%m/%d/%y"
502 decode 'd' = show2 day -- day of the month
503 decode 'e' = show2' day -- ditto, padded
504 decode 'H' = show2 hour -- hours, 24-hour clock, padded
505 decode 'I' = show2 (to12 hour) -- hours, 12-hour clock
506 decode 'j' = show3 yday -- day of the year
507 decode 'k' = show2' hour -- hours, 24-hour clock, no padding
508 decode 'l' = show2' (to12 hour) -- hours, 12-hour clock, no padding
509 decode 'M' = show2 min -- minutes
510 decode 'm' = show2 (fromEnum mon+1) -- numeric month
512 decode 'p' = (if hour < 12 then fst else snd) (amPm l) -- am or pm
513 decode 'R' = doFmt "%H:%M"
514 decode 'r' = doFmt (time12Fmt l)
515 decode 'T' = doFmt "%H:%M:%S"
517 decode 'S' = show2 sec -- seconds
518 decode 's' = show2 sec -- number of secs since Epoch. (ToDo.)
519 decode 'U' = show2 ((yday + 7 - fromEnum wday) `div` 7) -- week number, starting on Sunday.
520 decode 'u' = show (let n = fromEnum wday in -- numeric day of the week (1=Monday, 7=Sunday)
521 if n == 0 then 7 else n)
522 decode 'V' = -- week number (as per ISO-8601.)
523 let (week, days) = -- [yep, I've always wanted to be able to display that too.]
524 (yday + 7 - if fromEnum wday > 0 then
525 fromEnum wday - 1 else 6) `divMod` 7
526 in show2 (if days >= 4 then
528 else if week == 0 then 53 else week)
530 decode 'W' = -- week number, weeks starting on monday
531 show2 ((yday + 7 - if fromEnum wday > 0 then
532 fromEnum wday - 1 else 6) `div` 7)
533 decode 'w' = show (fromEnum wday) -- numeric day of the week, weeks starting on Sunday.
534 decode 'X' = doFmt (timeFmt l) -- locale's preferred way of printing time.
535 decode 'x' = doFmt (dateFmt l) -- locale's preferred way of printing dates.
536 decode 'Y' = show year -- year, including century.
537 decode 'y' = show2 (year `rem` 100) -- year, within century.
538 decode 'Z' = tzname -- timezone name
543 show2, show2', show3 :: Int -> String
545 | x' < 10 = '0': show x'
546 | otherwise = show x'
547 where x' = x `rem` 100
550 | x' < 10 = ' ': show x'
551 | otherwise = show x'
552 where x' = x `rem` 100
554 show3 x = show (x `quot` 100) ++ show2 (x `rem` 100)
555 where x' = x `rem` 1000
558 to12 h = let h' = h `mod` 12 in if h' == 0 then 12 else h'
560 -- Useful extensions for formatting TimeDiffs.
562 timeDiffToString :: TimeDiff -> String
563 timeDiffToString = formatTimeDiff defaultTimeLocale "%c"
565 formatTimeDiff :: TimeLocale -> String -> TimeDiff -> String
566 formatTimeDiff l fmt td@(TimeDiff year month day hour min sec _)
570 doFmt ('%':'-':cs) = doFmt ('%':cs) -- padding not implemented
571 doFmt ('%':'_':cs) = doFmt ('%':cs) -- padding not implemented
572 doFmt ('%':c:cs) = decode c ++ doFmt cs
573 doFmt (c:cs) = c : doFmt cs
577 'B' -> fst (months l !! fromEnum month)
578 'b' -> snd (months l !! fromEnum month)
579 'h' -> snd (months l !! fromEnum month)
580 'c' -> defaultTimeDiffFmt td
581 'C' -> show2 (year `quot` 100)
582 'D' -> doFmt "%m/%d/%y"
586 'I' -> show2 (to12 hour)
588 'l' -> show2' (to12 hour)
590 'm' -> show2 (fromEnum month + 1)
592 'p' -> (if hour < 12 then fst else snd) (amPm l)
594 'r' -> doFmt (time12Fmt l)
595 'T' -> doFmt "%H:%M:%S"
598 's' -> show2 sec -- Implementation-dependent, sez the lib doc..
599 'X' -> doFmt (timeFmt l)
600 'x' -> doFmt (dateFmt l)
602 'y' -> show2 (year `rem` 100)
606 defaultTimeDiffFmt (TimeDiff year month day hour min sec _) =
607 foldr (\ (v,s) rest ->
609 then show v ++ ' ':(addS v s)
610 ++ if null rest then "" else ", "
614 (zip [year, month, day, hour, min, sec] (intervals l))
616 addS v s = if abs v == 1 then fst s else snd s
619 -- -----------------------------------------------------------------------------
620 -- Foreign time interface (POSIX)
622 type CTm = () -- struct tm
625 foreign import ccall unsafe localtime_r :: Ptr CTime -> Ptr CTm -> IO (Ptr CTm)
627 foreign import ccall unsafe localtime :: Ptr CTime -> IO (Ptr CTm)
630 foreign import ccall unsafe gmtime_r :: Ptr CTime -> Ptr CTm -> IO (Ptr CTm)
632 foreign import ccall unsafe gmtime :: Ptr CTime -> IO (Ptr CTm)
634 foreign import ccall unsafe mktime :: Ptr CTm -> IO CTime
635 foreign import ccall unsafe time :: Ptr CTime -> IO CTime
637 #if HAVE_GETTIMEOFDAY
639 foreign import ccall unsafe gettimeofday :: Ptr CTimeVal -> Ptr () -> IO CInt
644 #ifndef mingw32_TARGET_OS
645 foreign import ccall unsafe ftime :: Ptr CTimeB -> IO CInt
647 foreign import ccall unsafe ftime :: Ptr CTimeB -> IO ()