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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 ...>)
>>>
"""
from datetime import (
datetime,
timedelta,
tzinfo
)
from decimal import Decimal
import logging
import sys
import re
__all__ = ["parse_date", "ParseError"]
LOG = logging.getLogger(__name__)
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})
(-{0,1}(?P<month>[0-9]{1,2})){1}
(-{0,1}(?P<day>[0-9]{1,2})){1}
(
(?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}
""",
re.VERBOSE
)
class ParseError(Exception):
"""Raised when there is a problem parsing a date string"""
# Yoinked from python docs
ZERO = timedelta(0)
class Utc(tzinfo):
"""UTC
"""
def utcoffset(self, dt):
return ZERO
def tzname(self, dt):
return "UTC"
def dst(self, dt):
return ZERO
UTC = Utc()
class FixedOffset(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 = 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)
)
if isinstance(other, tzinfo):
return other == self
return False
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):
"""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, default)
LOG.debug("Got %r for %r with default %r", value, key, default)
if (value in ["", None]) and default_to_zero:
return 0
if value is None:
raise ParseError("Unable to read %s from %s" % (key, d))
return int(value)
def parse_timezone(matches, default_timezone=UTC):
"""Parses ISO 8601 time zone specs into tzinfo offsets
"""
if matches["timezone"] == "Z":
return default_timezone
# 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
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.
"""
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()
LOG.debug("Parsed %s into %s with default timezone %s", datestring, groups, default_timezone)
tz = parse_timezone(groups, default_timezone=default_timezone)
groups["second_fraction"] = int(Decimal("0.%s" % to_int(groups, "second_fraction", default_to_zero=True)) * Decimal("1000000.0"))
try:
return datetime(
year=to_int(groups, "year"),
month=to_int(groups, "month"),
day=to_int(groups, "day"),
hour=to_int(groups, "hour"),
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)
|
