Lib/tzparse.py

   1 """Parse a timezone specification."""
   2
   3 # XXX Unfinished.
   4 # XXX Only the typical form "XXXhhYYY;ddd/hh,ddd/hh" is currently supported.
   5
   6 import warnings
   7 warnings.warn(
   8     "The tzparse module is obsolete and will disappear in the future",
   9     DeprecationWarning)
  10
  11 tzpat = ('^([A-Z][A-Z][A-Z])([-+]?[0-9]+)([A-Z][A-Z][A-Z]);'
  12           '([0-9]+)/([0-9]+),([0-9]+)/([0-9]+)$')
  13
  14 tzprog = None
  15
  16 def tzparse(tzstr):
  17     """Given a timezone spec, return a tuple of information
  18     (tzname, delta, dstname, daystart, hourstart, dayend, hourend),
  19     where 'tzname' is the name of the timezone, 'delta' is the offset
  20     in hours from GMT, 'dstname' is the name of the daylight-saving
  21     timezone, and 'daystart'/'hourstart' and 'dayend'/'hourend'
  22     specify the starting and ending points for daylight saving time."""
  23     global tzprog
  24     if tzprog is None:
  25         import re
  26         tzprog = re.compile(tzpat)
  27     match = tzprog.match(tzstr)
  28     if not match:
  29         raise ValueError, 'not the TZ syntax I understand'
  30     subs = []
  31     for i in range(1, 8):
  32         subs.append(match.group(i))
  33     for i in (1, 3, 4, 5, 6):
  34         subs[i] = eval(subs[i])
  35     [tzname, delta, dstname, daystart, hourstart, dayend, hourend] = subs
  36     return (tzname, delta, dstname, daystart, hourstart, dayend, hourend)
  37
  38 def tzlocaltime(secs, params):
  39     """Given a Unix time in seconds and a tuple of information about
  40     a timezone as returned by tzparse(), return the local time in the
  41     form (year, month, day, hour, min, sec, yday, wday, tzname)."""
  42     import time
  43     (tzname, delta, dstname, daystart, hourstart, dayend, hourend) = params
  44     year, month, days, hours, mins, secs, yday, wday, isdst = \
  45             time.gmtime(secs - delta*3600)
  46     if (daystart, hourstart) <= (yday+1, hours) < (dayend, hourend):
  47         tzname = dstname
  48         hours = hours + 1
  49     return year, month, days, hours, mins, secs, yday, wday, tzname
  50
  51 def tzset():
  52     """Determine the current timezone from the "TZ" environment variable."""
  53     global tzparams, timezone, altzone, daylight, tzname
  54     import os
  55     tzstr = os.environ['TZ']
  56     tzparams = tzparse(tzstr)
  57     timezone = tzparams[1] * 3600
  58     altzone = timezone - 3600
  59     daylight = 1
  60     tzname = tzparams[0], tzparams[2]
  61
  62 def isdst(secs):
  63     """Return true if daylight-saving time is in effect for the given
  64     Unix time in the current timezone."""
  65     import time
  66     (tzname, delta, dstname, daystart, hourstart, dayend, hourend) = \
  67             tzparams
  68     year, month, days, hours, mins, secs, yday, wday, isdst = \
  69             time.gmtime(secs - delta*3600)
  70     return (daystart, hourstart) <= (yday+1, hours) < (dayend, hourend)
  71
  72 tzset()
  73
  74 def localtime(secs):
  75     """Get the local time in the current timezone."""
  76     return tzlocaltime(secs, tzparams)
  77
  78 def test():
  79     from time import asctime, gmtime
  80     import time, sys
  81     now = time.time()
  82     x = localtime(now)
  83     tm = x[:-1] + (0,)
  84     print 'now =', now, '=', asctime(tm), x[-1]
  85     now = now - now % (24*3600)
  86     if sys.argv[1:]: now = now + eval(sys.argv[1])
  87     x = gmtime(now)
  88     tm = x[:-1] + (0,)
  89     print 'gmtime =', now, '=', asctime(tm), 'yday =', x[-2]
  90     jan1 = now - x[-2]*24*3600
  91     x = localtime(jan1)
  92     tm = x[:-1] + (0,)
  93     print 'jan1 =', jan1, '=', asctime(tm), x[-1]
  94     for d in range(85, 95) + range(265, 275):
  95         t = jan1 + d*24*3600
  96         x = localtime(t)
  97         tm = x[:-1] + (0,)
  98         print 'd =', d, 't =', t, '=', asctime(tm), x[-1]