/usr/lib/python3/dist-packages/pytz/tzfile.py is in python3-tz 2012c-1build1.
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 | #!/usr/bin/env python
'''
$Id: tzfile.py,v 1.8 2004/06/03 00:15:24 zenzen Exp $
'''
try:
from cStringIO import StringIO
except ImportError:
from io import StringIO
from datetime import datetime, timedelta
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('US-ASCII')
_NULL = _byte_string('\0')
def _std_string(s):
"""Cast a string or byte string to an ASCII string."""
return str(s.decode('US-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(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
# Patched in Debian, use the system zoninfo from the tzdata package
base = '/usr/share/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)
#print tz.asPython(4)
#print tz.transitions_mapping
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