You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
134 lines
4.6 KiB
Python
134 lines
4.6 KiB
Python
'''
|
|
$Id: tzfile.py,v 1.8 2004/06/03 00:15:24 zenzen Exp $
|
|
'''
|
|
|
|
from datetime import datetime
|
|
from struct import unpack, calcsize
|
|
|
|
from pytz.tzinfo import StaticTzInfo, DstTzInfo, memorized_ttinfo
|
|
from pytz.tzinfo import memorized_datetime, memorized_timedelta
|
|
|
|
|
|
def _byte_string(s):
|
|
"""Cast a string or byte string to an ASCII byte string."""
|
|
return s.encode('ASCII')
|
|
|
|
_NULL = _byte_string('\0')
|
|
|
|
|
|
def _std_string(s):
|
|
"""Cast a string or byte string to an ASCII string."""
|
|
return str(s.decode('ASCII'))
|
|
|
|
|
|
def build_tzinfo(zone, fp):
|
|
head_fmt = '>4s c 15x 6l'
|
|
head_size = calcsize(head_fmt)
|
|
(magic, format, ttisgmtcnt, ttisstdcnt, leapcnt, timecnt,
|
|
typecnt, charcnt) = unpack(head_fmt, fp.read(head_size))
|
|
|
|
# Make sure it is a tzfile(5) file
|
|
assert magic == _byte_string('TZif'), 'Got magic %s' % repr(magic)
|
|
|
|
# Read out the transition times, localtime indices and ttinfo structures.
|
|
data_fmt = '>%(timecnt)dl %(timecnt)dB %(ttinfo)s %(charcnt)ds' % dict(
|
|
timecnt=timecnt, ttinfo='lBB' * typecnt, charcnt=charcnt)
|
|
data_size = calcsize(data_fmt)
|
|
data = unpack(data_fmt, fp.read(data_size))
|
|
|
|
# make sure we unpacked the right number of values
|
|
assert len(data) == 2 * timecnt + 3 * typecnt + 1
|
|
transitions = [memorized_datetime(trans)
|
|
for trans in data[:timecnt]]
|
|
lindexes = list(data[timecnt:2 * timecnt])
|
|
ttinfo_raw = data[2 * timecnt:-1]
|
|
tznames_raw = data[-1]
|
|
del data
|
|
|
|
# Process ttinfo into separate structs
|
|
ttinfo = []
|
|
tznames = {}
|
|
i = 0
|
|
while i < len(ttinfo_raw):
|
|
# have we looked up this timezone name yet?
|
|
tzname_offset = ttinfo_raw[i + 2]
|
|
if tzname_offset not in tznames:
|
|
nul = tznames_raw.find(_NULL, tzname_offset)
|
|
if nul < 0:
|
|
nul = len(tznames_raw)
|
|
tznames[tzname_offset] = _std_string(
|
|
tznames_raw[tzname_offset:nul])
|
|
ttinfo.append((ttinfo_raw[i],
|
|
bool(ttinfo_raw[i + 1]),
|
|
tznames[tzname_offset]))
|
|
i += 3
|
|
|
|
# Now build the timezone object
|
|
if len(ttinfo) == 1 or len(transitions) == 0:
|
|
ttinfo[0][0], ttinfo[0][2]
|
|
cls = type(zone, (StaticTzInfo,), dict(
|
|
zone=zone,
|
|
_utcoffset=memorized_timedelta(ttinfo[0][0]),
|
|
_tzname=ttinfo[0][2]))
|
|
else:
|
|
# Early dates use the first standard time ttinfo
|
|
i = 0
|
|
while ttinfo[i][1]:
|
|
i += 1
|
|
if ttinfo[i] == ttinfo[lindexes[0]]:
|
|
transitions[0] = datetime.min
|
|
else:
|
|
transitions.insert(0, datetime.min)
|
|
lindexes.insert(0, i)
|
|
|
|
# calculate transition info
|
|
transition_info = []
|
|
for i in range(len(transitions)):
|
|
inf = ttinfo[lindexes[i]]
|
|
utcoffset = inf[0]
|
|
if not inf[1]:
|
|
dst = 0
|
|
else:
|
|
for j in range(i - 1, -1, -1):
|
|
prev_inf = ttinfo[lindexes[j]]
|
|
if not prev_inf[1]:
|
|
break
|
|
dst = inf[0] - prev_inf[0] # dst offset
|
|
|
|
# Bad dst? Look further. DST > 24 hours happens when
|
|
# a timzone has moved across the international dateline.
|
|
if dst <= 0 or dst > 3600 * 3:
|
|
for j in range(i + 1, len(transitions)):
|
|
stdinf = ttinfo[lindexes[j]]
|
|
if not stdinf[1]:
|
|
dst = inf[0] - stdinf[0]
|
|
if dst > 0:
|
|
break # Found a useful std time.
|
|
|
|
tzname = inf[2]
|
|
|
|
# Round utcoffset and dst to the nearest minute or the
|
|
# datetime library will complain. Conversions to these timezones
|
|
# might be up to plus or minus 30 seconds out, but it is
|
|
# the best we can do.
|
|
utcoffset = int((utcoffset + 30) // 60) * 60
|
|
dst = int((dst + 30) // 60) * 60
|
|
transition_info.append(memorized_ttinfo(utcoffset, dst, tzname))
|
|
|
|
cls = type(zone, (DstTzInfo,), dict(
|
|
zone=zone,
|
|
_utc_transition_times=transitions,
|
|
_transition_info=transition_info))
|
|
|
|
return cls()
|
|
|
|
if __name__ == '__main__':
|
|
import os.path
|
|
from pprint import pprint
|
|
base = os.path.join(os.path.dirname(__file__), 'zoneinfo')
|
|
tz = build_tzinfo('Australia/Melbourne',
|
|
open(os.path.join(base, 'Australia', 'Melbourne'), 'rb'))
|
|
tz = build_tzinfo('US/Eastern',
|
|
open(os.path.join(base, 'US', 'Eastern'), 'rb'))
|
|
pprint(tz._utc_transition_times)
|