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Limnoria/others/dateutil/tz.py
Jeremy Fincher 27fe6554c7 Changing to a different date parsing module.
2004-09-30 07:40:45 +00:00

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"""
Copyright (c) 2003 Gustavo Niemeyer <niemeyer@conectiva.com>
This module offers extensions to the standard python 2.3+
datetime module.
"""
__author__ = "Gustavo Niemeyer <niemeyer@conectiva.com>"
__license__ = "PSF License"
import datetime
import struct
import time
relativedelta = None
parser = None
rrule = None
__all__ = ["tzutc", "tzoffset", "tzlocal", "tzfile",
"tzrange", "tzstr", "tzical", "gettz"]
ZERO = datetime.timedelta(0)
EPOCHORDINAL = datetime.datetime.utcfromtimestamp(0).toordinal()
class tzutc(datetime.tzinfo):
def utcoffset(self, dt):
return ZERO
def dst(self, dt):
return ZERO
def tzname(self, dt):
return "UTC"
def __eq__(self, other):
return (isinstance(other, tzutc) or
(isinstance(other, tzoffset) and other._offset == ZERO))
def __ne__(self, other):
return not self.__eq__(other)
def __repr__(self):
return "%s()" % self.__class__.__name__
class tzoffset(datetime.tzinfo):
def __init__(self, name, offset):
self._name = name
self._offset = datetime.timedelta(seconds=offset)
def utcoffset(self, dt):
return self._offset
def dst(self, dt):
return ZERO
def tzname(self, dt):
return self._name
def __eq__(self, other):
return (isinstance(other, tzoffset) and
self._offset == other._offset)
def __ne__(self, other):
return not self.__eq__(other)
def __repr__(self):
return "%s(%s, %s)" % (self.__class__.__name__,
`self._name`,
self._offset.days*86400+self._offset.seconds)
class tzlocal(datetime.tzinfo):
_std_offset = datetime.timedelta(seconds=-time.timezone)
if time.daylight:
_dst_offset = datetime.timedelta(seconds=-time.altzone)
else:
_dst_offset = _std_offset
def utcoffset(self, dt):
if self._isdst(dt):
return self._dst_offset
else:
return self._std_offset
def dst(self, dt):
if self._isdst(dt):
return self._dst_offset-self._std_offset
else:
return ZERO
def tzname(self, dt):
return time.tzname[self._isdst(dt)]
def _isdst(self, dt):
# We can't use mktime here. It is unstable when deciding if
# the hour near to a change is DST or not.
#
# timestamp = time.mktime((dt.year, dt.month, dt.day, dt.hour,
# dt.minute, dt.second, dt.weekday(), 0, -1))
# return time.localtime(timestamp).tm_isdst
#
# The code above yields the following result:
#
#>>> import tz, datetime
#>>> t = tz.tzlocal()
#>>> datetime.datetime(2003,2,15,23,tzinfo=t).tzname()
#'BRDT'
#>>> datetime.datetime(2003,2,16,0,tzinfo=t).tzname()
#'BRST'
#>>> datetime.datetime(2003,2,15,23,tzinfo=t).tzname()
#'BRST'
#>>> datetime.datetime(2003,2,15,22,tzinfo=t).tzname()
#'BRDT'
#>>> datetime.datetime(2003,2,15,23,tzinfo=t).tzname()
#'BRDT'
#
# Here is a more stable implementation:
#
timestamp = ((dt.toordinal() - EPOCHORDINAL) * 86400
+ dt.hour * 3600
+ dt.minute * 60
+ dt.second)
return time.localtime(timestamp+time.timezone).tm_isdst
def __eq__(self, other):
if not isinstance(other, tzlocal):
return False
return (self._std_offset == other._std_offset and
self._dst_offset == other._dst_offset)
return True
def __ne__(self, other):
return not self.__eq__(other)
def __repr__(self):
return "%s()" % self.__class__.__name__
class _ttinfo(object):
__slots__ = ["offset", "delta", "isdst", "abbr", "isstd", "isgmt"]
def __init__(self):
for attr in self.__slots__:
setattr(self, attr, None)
def __repr__(self):
l = []
for attr in self.__slots__:
value = getattr(self, attr)
if value is not None:
l.append("%s=%s" % (attr, `value`))
return "%s(%s)" % (self.__class__.__name__, ", ".join(l))
def __eq__(self, other):
if not isinstance(other, _ttinfo):
return False
return (self.offset == other.offset and
self.delta == other.delta and
self.isdst == other.isdst and
self.abbr == other.abbr and
self.isstd == other.isstd and
self.isgmt == other.isgmt)
def __ne__(self, other):
return not self.__eq__(other)
class tzfile(datetime.tzinfo):
# http://www.twinsun.com/tz/tz-link.htm
# ftp://elsie.nci.nih.gov/pub/tz*.tar.gz
def __init__(self, fileobj):
if isinstance(fileobj, basestring):
self._s = fileobj
fileobj = open(fileobj)
elif hasattr(fileobj, "name"):
self._s = fileobj.name
else:
self._s = `fileobj`
# From tzfile(5):
#
# The time zone information files used by tzset(3)
# begin with the magic characters "TZif" to identify
# them as time zone information files, followed by
# sixteen bytes reserved for future use, followed by
# six four-byte values of type long, written in a
# ``standard'' byte order (the high-order byte
# of the value is written first).
if fileobj.read(4) != "TZif":
raise ValueError, "magic not found"
fileobj.read(16)
(
# The number of UTC/local indicators stored in the file.
ttisgmtcnt,
# The number of standard/wall indicators stored in the file.
ttisstdcnt,
# The number of leap seconds for which data is
# stored in the file.
leapcnt,
# The number of "transition times" for which data
# is stored in the file.
timecnt,
# The number of "local time types" for which data
# is stored in the file (must not be zero).
typecnt,
# The number of characters of "time zone
# abbreviation strings" stored in the file.
charcnt,
) = struct.unpack(">6l", fileobj.read(24))
# The above header is followed by tzh_timecnt four-byte
# values of type long, sorted in ascending order.
# These values are written in ``standard'' byte order.
# Each is used as a transition time (as returned by
# time(2)) at which the rules for computing local time
# change.
if timecnt:
self._trans_list = struct.unpack(">%dl" % timecnt,
fileobj.read(timecnt*4))
else:
self._trans_list = []
# Next come tzh_timecnt one-byte values of type unsigned
# char; each one tells which of the different types of
# ``local time'' types described in the file is associated
# with the same-indexed transition time. These values
# serve as indices into an array of ttinfo structures that
# appears next in the file.
if timecnt:
self._trans_idx = struct.unpack(">%dB" % timecnt,
fileobj.read(timecnt))
else:
self._trans_idx = []
# Each ttinfo structure is written as a four-byte value
# for tt_gmtoff of type long, in a standard byte
# order, followed by a one-byte value for tt_isdst
# and a one-byte value for tt_abbrind. In each
# structure, tt_gmtoff gives the number of
# seconds to be added to UTC, tt_isdst tells whether
# tm_isdst should be set by localtime(3), and
# tt_abbrind serves as an index into the array of
# time zone abbreviation characters that follow the
# ttinfo structure(s) in the file.
ttinfo = []
for i in range(typecnt):
ttinfo.append(struct.unpack(">lbb", fileobj.read(6)))
abbr = fileobj.read(charcnt)
# Then there are tzh_leapcnt pairs of four-byte
# values, written in standard byte order; the
# first value of each pair gives the time (as
# returned by time(2)) at which a leap second
# occurs; the second gives the total number of
# leap seconds to be applied after the given time.
# The pairs of values are sorted in ascending order
# by time.
# Not used, for now
if leapcnt:
leap = struct.unpack(">%dl" % leapcnt*2,
fileobj.read(leapcnt*8))
# Then there are tzh_ttisstdcnt standard/wall
# indicators, each stored as a one-byte value;
# they tell whether the transition times associated
# with local time types were specified as standard
# time or wall clock time, and are used when
# a time zone file is used in handling POSIX-style
# time zone environment variables.
if ttisstdcnt:
isstd = struct.unpack(">%db" % ttisstdcnt,
fileobj.read(ttisstdcnt))
# Finally, there are tzh_ttisgmtcnt UTC/local
# indicators, each stored as a one-byte value;
# they tell whether the transition times associated
# with local time types were specified as UTC or
# local time, and are used when a time zone file
# is used in handling POSIX-style time zone envi-
# ronment variables.
if ttisgmtcnt:
isgmt = struct.unpack(">%db" % ttisgmtcnt,
fileobj.read(ttisgmtcnt))
# ** Everything has been read **
# Build ttinfo list
self._ttinfo_list = []
for i in range(typecnt):
tti = _ttinfo()
tti.offset = ttinfo[i][0]
tti.delta = datetime.timedelta(seconds=ttinfo[i][0])
tti.isdst = ttinfo[i][1]
tti.abbr = abbr[ttinfo[i][2]:abbr.find('\x00', ttinfo[i][2])]
tti.isstd = (ttisstdcnt > i and isstd[i] != 0)
tti.isgmt = (ttisgmtcnt > i and isgmt[i] != 0)
self._ttinfo_list.append(tti)
# Replace ttinfo indexes for ttinfo objects.
trans_idx = []
for idx in self._trans_idx:
trans_idx.append(self._ttinfo_list[idx])
self._trans_idx = tuple(trans_idx)
# Set standard, dst, and before ttinfos. before will be
# used when a given time is before any transitions,
# and will be set to the first non-dst ttinfo, or to
# the first dst, if all of them are dst.
self._ttinfo_std = None
self._ttinfo_dst = None
self._ttinfo_before = None
if self._ttinfo_list:
if not self._trans_list:
self._ttinfo_std = self._ttinfo_first = self._ttinfo_list[0]
else:
for i in range(timecnt-1,-1,-1):
tti = self._trans_idx[i]
if not self._ttinfo_std and not tti.isdst:
self._ttinfo_std = tti
elif not self._ttinfo_dst and tti.isdst:
self._ttinfo_dst = tti
if self._ttinfo_std and self._ttinfo_dst:
break
else:
if self._ttinfo_dst and not self._ttinfo_std:
self._ttinfo_std = self._ttinfo_dst
for tti in self._ttinfo_list:
if not tti.isdst:
self._ttinfo_before = tti
break
else:
self._ttinfo_before = self._ttinfo_list[0]
# Now fix transition times to become relative to wall time.
#
# I'm not sure about this. In my tests, the tz source file
# is setup to wall time, and in the binary file isstd and
# isgmt are off, so it should be in wall time. OTOH, it's
# always in gmt time. Let me know if you have comments
# about this.
laststdoffset = 0
self._trans_list = list(self._trans_list)
for i in range(len(self._trans_list)):
tti = self._trans_idx[i]
if not tti.isdst:
# This is std time.
self._trans_list[i] += tti.offset
laststdoffset = tti.offset
else:
# This is dst time. Convert to std.
self._trans_list[i] += laststdoffset
self._trans_list = tuple(self._trans_list)
def _find_ttinfo(self, dt, laststd=0):
timestamp = ((dt.toordinal() - EPOCHORDINAL) * 86400
+ dt.hour * 3600
+ dt.minute * 60
+ dt.second)
idx = 0
for trans in self._trans_list:
if timestamp < trans:
break
idx += 1
else:
return self._ttinfo_std
if idx == 0:
return self._ttinfo_before
if laststd:
while idx > 0:
tti = self._trans_idx[idx-1]
if not tti.isdst:
return tti
idx -= 1
else:
return self._ttinfo_std
else:
return self._trans_idx[idx-1]
def utcoffset(self, dt):
if not self._ttinfo_std:
return ZERO
return self._find_ttinfo(dt).delta
def dst(self, dt):
if not self._ttinfo_dst:
return ZERO
tti = self._find_ttinfo(dt)
if not tti.isdst:
return ZERO
# The documentation says that utcoffset()-dst() must
# be constant for every dt.
return self._find_ttinfo(dt, laststd=1).delta-tti.delta
# An alternative for that would be:
#
# return self._ttinfo_dst.offset-self._ttinfo_std.offset
#
# However, this class stores historical changes in the
# dst offset, so I belive that this wouldn't be the right
# way to implement this.
def tzname(self, dt):
if not self._ttinfo_std:
return None
return self._find_ttinfo(dt).abbr
def __eq__(self, other):
if not isinstance(other, tzfile):
return False
return (self._trans_list == other._trans_list and
self._trans_idx == other._trans_idx and
self._ttinfo_list == other._ttinfo_list)
def __ne__(self, other):
return not self.__eq__(other)
def __repr__(self):
return "%s(%s)" % (self.__class__.__name__, `self._s`)
class tzrange(datetime.tzinfo):
def __init__(self, stdabbr, stdoffset=None,
dstabbr=None, dstoffset=None,
start=None, end=None):
global relativedelta
if not relativedelta:
from dateutil import relativedelta
self._std_abbr = stdabbr
self._dst_abbr = dstabbr
if stdoffset is not None:
self._std_offset = datetime.timedelta(seconds=stdoffset)
else:
self._std_offset = ZERO
if dstoffset is not None:
self._dst_offset = datetime.timedelta(seconds=dstoffset)
elif dstabbr and stdoffset is not None:
self._dst_offset = self._std_offset+datetime.timedelta(hours=+1)
else:
self._dst_offset = ZERO
if start is None:
self._start_delta = relativedelta.relativedelta(
hours=+2, month=4, day=1, weekday=relativedelta.SU(+1))
else:
self._start_delta = start
if end is None:
self._end_delta = relativedelta.relativedelta(
hours=+1, month=10, day=31, weekday=relativedelta.SU(-1))
else:
self._end_delta = end
def utcoffset(self, dt):
if self._isdst(dt):
return self._dst_offset
else:
return self._std_offset
def dst(self, dt):
if self._isdst(dt):
return self._dst_offset-self._std_offset
else:
return ZERO
def tzname(self, dt):
if self._isdst(dt):
return self._dst_abbr
else:
return self._std_abbr
def _isdst(self, dt):
if not self._start_delta:
return False
year = datetime.date(dt.year,1,1)
start = year+self._start_delta
end = year+self._end_delta
dt = dt.replace(tzinfo=None)
if start < end:
return dt >= start and dt < end
else:
return dt >= start or dt < end
def __eq__(self, other):
if not isinstance(other, tzrange):
return False
return (self._std_abbr == other._std_abbr and
self._dst_abbr == other._dst_abbr and
self._std_offset == other._std_offset and
self._dst_offset == other._dst_offset and
self._start_delta == other._start_delta and
self._end_delta == other._end_delta)
def __ne__(self, other):
return not self.__eq__(other)
def __repr__(self):
return "%s(...)" % self.__class__.__name__
class tzstr(tzrange):
def __init__(self, s):
global parser
if not parser:
from dateutil import parser
self._s = s
res = parser._parsetz(s)
if res is None:
raise ValueError, "unknown string format"
# We must initialize it first, since _delta() needs
# _std_offset and _dst_offset set. Use False in start/end
# to avoid building it two times.
tzrange.__init__(self, res.stdabbr, res.stdoffset,
res.dstabbr, res.dstoffset,
start=False, end=False)
self._start_delta = self._delta(res.start)
if self._start_delta:
self._end_delta = self._delta(res.end, isend=1)
def _delta(self, x, isend=0):
kwargs = {}
if x.month is not None:
kwargs["month"] = x.month
if x.weekday is not None:
kwargs["weekday"] = relativedelta.weekday(x.weekday, x.week)
if x.week > 0:
kwargs["day"] = 1
else:
kwargs["day"] = 31
elif x.day:
kwargs["day"] = x.day
elif x.yday is not None:
kwargs["yearday"] = x.yday
elif x.jyday is not None:
kwargs["nlyearday"] = x.jyday
if not kwargs:
# Default is to start on first sunday of april, and end
# on last sunday of october.
if not isend:
kwargs["month"] = 4
kwargs["day"] = 1
kwargs["weekday"] = relativedelta.SU(+1)
else:
kwargs["month"] = 10
kwargs["day"] = 31
kwargs["weekday"] = relativedelta.SU(-1)
if x.time is not None:
kwargs["seconds"] = x.time
else:
# Default is 2AM.
kwargs["seconds"] = 7200
if isend:
# Convert to standard time, to follow the documented way
# of working with the extra hour. See the documentation
# of the tzinfo class.
delta = self._dst_offset-self._std_offset
kwargs["seconds"] -= delta.seconds+delta.days*86400
return relativedelta.relativedelta(**kwargs)
def __repr__(self):
return "%s(%s)" % (self.__class__.__name__, `self._s`)
class _tzicalvtzcomp:
def __init__(self, tzoffsetfrom, tzoffsetto, isdst,
tzname=None, rrule=None):
self.tzoffsetfrom = datetime.timedelta(seconds=tzoffsetfrom)
self.tzoffsetto = datetime.timedelta(seconds=tzoffsetto)
self.tzoffsetdiff = self.tzoffsetto-self.tzoffsetfrom
self.isdst = isdst
self.tzname = tzname
self.rrule = rrule
class _tzicalvtz(datetime.tzinfo):
def __init__(self, tzid, comps=[]):
self._tzid = tzid
self._comps = comps
self._cachedate = []
self._cachecomp = []
def _find_comp(self, dt):
if len(self._comps) == 1:
return self._comps[0]
dt = dt.replace(tzinfo=None)
try:
return self._cachecomp[self._cachedate.index(dt)]
except ValueError:
pass
lastcomp = None
lastcompdt = None
for comp in self._comps:
if not comp.isdst:
# Handle the extra hour in DST -> STD
compdt = comp.rrule.before(dt-comp.tzoffsetdiff, inc=True)
else:
compdt = comp.rrule.before(dt, inc=True)
if compdt and (not lastcompdt or lastcompdt < compdt):
lastcompdt = compdt
lastcomp = comp
if not lastcomp:
# RFC says nothing about what to do when a given
# time is before the first onset date. We'll look for the
# first standard component, or the first component, if
# none is found.
for comp in self._comps:
if not comp.isdst:
lastcomp = comp
break
else:
lastcomp = comp[0]
self._cachedate.insert(0, dt)
self._cachecomp.insert(0, lastcomp)
if len(self._cachedate) > 10:
self._cachedate.pop()
self._cachecomp.pop()
return lastcomp
def utcoffset(self, dt):
return self._find_comp(dt).tzoffsetto
def dst(self, dt):
comp = self._find_comp(dt)
if comp.isdst:
return comp.tzoffsetdiff
else:
return ZERO
def tzname(self, dt):
return self._find_comp(dt).tzname
def __repr__(self):
return "<tzicalvtz %s>" % `self._tzid`
class tzical:
def __init__(self, fileobj):
global rrule
if not rrule:
from dateutil import rrule
if isinstance(fileobj, basestring):
self._s = fileobj
fileobj = open(fileobj)
elif hasattr(fileobj, "name"):
self._s = fileobj.name
else:
self._s = `fileobj`
self._vtz = {}
self._parse_rfc(fileobj.read())
def keys(self):
return self._vtz.keys()
def get(self, tzid=None):
if tzid is None:
keys = self._vtz.keys()
if len(keys) == 0:
raise "no timezones defined"
elif len(keys) > 1:
raise "more than one timezone available"
tzid = keys[0]
return self._vtz.get(tzid)
def _parse_offset(self, s):
s = s.strip()
if not s:
raise ValueError, "empty offset"
if s[0] in ('+', '-'):
signal = (-1,+1)[s[0]=='+']
s = s[1:]
else:
signal = +1
if len(s) == 4:
return (int(s[:2])*3600+int(s[2:])*60)*signal
elif len(s) == 6:
return (int(s[:2])*3600+int(s[2:4])*60+int(s[4:]))*signal
else:
raise ValueError, "invalid offset: "+s
def _parse_rfc(self, s):
lines = s.splitlines()
if not lines:
raise ValueError, "empty string"
# Unfold
i = 0
while i < len(lines):
line = lines[i].rstrip()
if not line:
del lines[i]
elif i > 0 and line[0] == " ":
lines[i-1] += line[1:]
del lines[i]
else:
i += 1
invtz = False
comptype = None
for line in lines:
if not line:
continue
name, value = line.split(':', 1)
parms = name.split(';')
if not parms:
raise ValueError, "empty property name"
name = parms[0].upper()
parms = parms[1:]
if invtz:
if name == "BEGIN":
if value in ("STANDARD", "DAYLIGHT"):
# Process component
pass
else:
raise ValueError, "unknown component: "+value
comptype = value
founddtstart = False
tzoffsetfrom = None
tzoffsetto = None
rrulelines = []
tzname = None
elif name == "END":
if value == "VTIMEZONE":
if comptype:
raise ValueError, \
"component not closed: "+comptype
if not tzid:
raise ValueError, \
"mandatory TZID not found"
if not comps:
raise ValueError, \
"at least one component is needed"
# Process vtimezone
self._vtz[tzid] = _tzicalvtz(tzid, comps)
invtz = False
elif value == comptype:
if not founddtstart:
raise ValueError, \
"mandatory DTSTART not found"
if not tzoffsetfrom:
raise ValueError, \
"mandatory TZOFFSETFROM not found"
if not tzoffsetto:
raise ValueError, \
"mandatory TZOFFSETFROM not found"
# Process component
rr = None
if rrulelines:
rr = rrule.rrulestr("\n".join(rrulelines),
compatible=True,
ignoretz=True,
cache=True)
comp = _tzicalvtzcomp(tzoffsetfrom, tzoffsetto,
(comptype == "DAYLIGHT"),
tzname, rr)
comps.append(comp)
comptype = None
else:
raise ValueError, \
"invalid component end: "+value
elif comptype:
if name == "DTSTART":
rrulelines.append(line)
founddtstart = True
elif name in ("RRULE", "RDATE", "EXRULE", "EXDATE"):
rrulelines.append(line)
elif name == "TZOFFSETFROM":
if parms:
raise ValueError, \
"unsupported %s parm: %s "%(name, parms[0])
tzoffsetfrom = self._parse_offset(value)
elif name == "TZOFFSETTO":
if parms:
raise ValueError, \
"unsupported TZOFFSETTO parm: "+parms[0]
tzoffsetto = self._parse_offset(value)
elif name == "TZNAME":
if parms:
raise ValueError, \
"unsupported TZNAME parm: "+parms[0]
tzname = value
elif name == "COMMENT":
pass
else:
raise ValueError, "unsupported property: "+name
else:
if name == "TZID":
if parms:
raise ValueError, \
"unsupported TZID parm: "+parms[0]
tzid = value
elif name in ("TZURL", "LAST-MODIFIED", "COMMENT"):
pass
else:
raise ValueError, "unsupported property: "+name
elif name == "BEGIN" and value == "VTIMEZONE":
tzid = None
comps = []
invtz = True
def __repr__(self):
return "%s(%s)" % (self.__class__.__name__, `self._s`)
TZFILES = ["/etc/localtime", "localtime"]
TZPATHS = ["/usr/share/zoneinfo", "/usr/lib/zoneinfo", "/etc/zoneinfo"]
import os
def gettz(name=None):
tz = None
if not name:
try:
name = os.environ["TZ"]
except KeyError:
pass
if name is None:
for filepath in TZFILES:
if not os.path.isabs(filepath):
filename = filepath
for path in TZPATHS:
filepath = os.path.join(path, filename)
if os.path.isfile(filepath):
break
else:
continue
if os.path.isfile(filepath):
try:
tz = tzfile(filepath)
break
except (IOError, OSError, ValueError):
pass
else:
if name and name[0] == ":":
name = name[:-1]
for path in TZPATHS:
filepath = os.path.join(path, name)
if not os.path.isfile(filepath):
filepath = filepath.replace(' ','_')
if not os.path.isfile(filepath):
continue
try:
tz = tzfile(filepath)
break
except (IOError, OSError, ValueError):
pass
else:
for c in name:
# name must have at least one offset to be a tzstr
if c in "0123456789":
try:
tz = tzstr(name)
except ValueError:
pass
break
else:
if name in ("GMT", "UTC"):
tz = tzutc()
elif name in time.tzname:
tz = tzlocal()
return tz
# vim:ts=4:sw=4:et
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