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|
"""ISO 8601 date time string parsing
Basic usage:
>>> import iso8601
>>> iso8601.parse_date("2007-01-25T12:00:00Z")
datetime.datetime(2007, 1, 25, 12, 0, tzinfo=<iso8601.iso8601.Utc ...>)
>>>
"""
import datetime
from decimal import Decimal
import sys
import re
__all__ = ["parse_date", "ParseError", "UTC",
"FixedOffset"]
if sys.version_info >= (3, 0, 0):
_basestring = str
else:
_basestring = basestring
# Adapted from http://delete.me.uk/2005/03/iso8601.html
ISO8601_REGEX = re.compile(
r"""
(?P<year>[0-9]{4})
(
(
(-(?P<monthdash>[0-9]{1,2}))
|
(?P<month>[0-9]{2})
(?!$) # Don't allow YYYYMM
)
(
(
(-(?P<daydash>[0-9]{1,2}))
|
(?P<day>[0-9]{2})
)
(
(
(?P<separator>[ T])
(?P<hour>[0-9]{2})
(:{0,1}(?P<minute>[0-9]{2})){0,1}
(
:{0,1}(?P<second>[0-9]{1,2})
([.,](?P<second_fraction>[0-9]+)){0,1}
){0,1}
(?P<timezone>
Z
|
(
(?P<tz_sign>[-+])
(?P<tz_hour>[0-9]{2})
:{0,1}
(?P<tz_minute>[0-9]{2}){0,1}
)
){0,1}
){0,1}
)
){0,1} # YYYY-MM
){0,1} # YYYY only
$
""",
re.VERBOSE
)
class ParseError(Exception):
"""Raised when there is a problem parsing a date string"""
if sys.version_info >= (3, 2, 0):
UTC = datetime.timezone.utc
def FixedOffset(offset_hours, offset_minutes, name):
return datetime.timezone(
datetime.timedelta(
hours=offset_hours, minutes=offset_minutes),
name)
else:
# Yoinked from python docs
ZERO = datetime.timedelta(0)
class Utc(datetime.tzinfo):
"""UTC Timezone
"""
def utcoffset(self, dt):
return ZERO
def tzname(self, dt):
return "UTC"
def dst(self, dt):
return ZERO
def __repr__(self):
return "<iso8601.Utc>"
UTC = Utc()
class FixedOffset(datetime.tzinfo):
"""Fixed offset in hours and minutes from UTC
"""
def __init__(self, offset_hours, offset_minutes, name):
self.__offset_hours = offset_hours # Keep for later __getinitargs__
self.__offset_minutes = offset_minutes # Keep for later __getinitargs__
self.__offset = datetime.timedelta(
hours=offset_hours, minutes=offset_minutes)
self.__name = name
def __eq__(self, other):
if isinstance(other, FixedOffset):
return (
(other.__offset == self.__offset)
and
(other.__name == self.__name)
)
return NotImplemented
def __getinitargs__(self):
return (self.__offset_hours, self.__offset_minutes, self.__name)
def utcoffset(self, dt):
return self.__offset
def tzname(self, dt):
return self.__name
def dst(self, dt):
return ZERO
def __repr__(self):
return "<FixedOffset %r %r>" % (self.__name, self.__offset)
def to_int(d, key, default_to_zero=False, default=None, required=True):
"""Pull a value from the dict and convert to int
:param default_to_zero: If the value is None or empty, treat it as zero
:param default: If the value is missing in the dict use this default
"""
value = d.get(key) or default
if (value in ["", None]) and default_to_zero:
return 0
if value is None:
if required:
raise ParseError("Unable to read %s from %s" % (key, d))
else:
return int(value)
def parse_timezone(matches, default_timezone=UTC):
"""Parses ISO 8601 time zone specs into tzinfo offsets
"""
if matches["timezone"] == "Z":
return UTC
# This isn't strictly correct, but it's common to encounter dates without
# timezones so I'll assume the default (which defaults to UTC).
# Addresses issue 4.
if matches["timezone"] is None:
return default_timezone
sign = matches["tz_sign"]
hours = to_int(matches, "tz_hour")
minutes = to_int(matches, "tz_minute", default_to_zero=True)
description = "%s%02d:%02d" % (sign, hours, minutes)
if sign == "-":
hours = -hours
minutes = -minutes
return FixedOffset(hours, minutes, description)
def parse_date(datestring, default_timezone=UTC):
"""Parses ISO 8601 dates into datetime objects
The timezone is parsed from the date string. However it is quite common to
have dates without a timezone (not strictly correct). In this case the
default timezone specified in default_timezone is used. This is UTC by
default.
:param datestring: The date to parse as a string
:param default_timezone: A datetime tzinfo instance to use when no timezone
is specified in the datestring. If this is set to
None then a naive datetime object is returned.
:returns: A datetime.datetime instance
:raises: ParseError when there is a problem parsing the date or
constructing the datetime instance.
"""
if not isinstance(datestring, _basestring):
raise ParseError("Expecting a string %r" % datestring)
m = ISO8601_REGEX.match(datestring)
if not m:
raise ParseError("Unable to parse date string %r" % datestring)
groups = m.groupdict()
tz = parse_timezone(groups, default_timezone=default_timezone)
groups["second_fraction"] = int(Decimal("0.%s" % (groups["second_fraction"] or 0)) * Decimal("1000000.0"))
try:
return datetime.datetime(
year=to_int(groups, "year"),
month=to_int(groups, "month", default=to_int(groups, "monthdash", required=False, default=1)),
day=to_int(groups, "day", default=to_int(groups, "daydash", required=False, default=1)),
hour=to_int(groups, "hour", default_to_zero=True),
minute=to_int(groups, "minute", default_to_zero=True),
second=to_int(groups, "second", default_to_zero=True),
microsecond=groups["second_fraction"],
tzinfo=tz,
)
except Exception as e:
raise ParseError(e)
|
