lib/subunit/python/subunit/iso8601.py

   1 # Copyright (c) 2007 Michael Twomey
   2 #
   3 # Permission is hereby granted, free of charge, to any person obtaining a
   4 # copy of this software and associated documentation files (the
   5 # "Software"), to deal in the Software without restriction, including
   6 # without limitation the rights to use, copy, modify, merge, publish,
   7 # distribute, sublicense, and/or sell copies of the Software, and to
   8 # permit persons to whom the Software is furnished to do so, subject to
   9 # the following conditions:
  10 #
  11 # The above copyright notice and this permission notice shall be included
  12 # in all copies or substantial portions of the Software.
  13 #
  14 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  15 # OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  16 # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  17 # IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  18 # CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  19 # TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  20 # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  21
  22 """ISO 8601 date time string parsing
  23
  24 Basic usage:
  25 >>> import iso8601
  26 >>> iso8601.parse_date("2007-01-25T12:00:00Z")
  27 datetime.datetime(2007, 1, 25, 12, 0, tzinfo=<iso8601.iso8601.Utc ...>)
  28 >>>
  29
  30 """
  31
  32 from datetime import datetime, timedelta, tzinfo
  33 import re
  34
  35 __all__ = ["parse_date", "ParseError"]
  36
  37 # Adapted from http://delete.me.uk/2005/03/iso8601.html
  38 ISO8601_REGEX = re.compile(r"(?P<year>[0-9]{4})(-(?P<month>[0-9]{1,2})(-(?P<day>[0-9]{1,2})"
  39     r"((?P<separator>.)(?P<hour>[0-9]{2}):(?P<minute>[0-9]{2})(:(?P<second>[0-9]{2})(\.(?P<fraction>[0-9]+))?)?"
  40     r"(?P<timezone>Z|(([-+])([0-9]{2}):([0-9]{2})))?)?)?)?"
  41 )
  42 TIMEZONE_REGEX = re.compile("(?P<prefix>[+-])(?P<hours>[0-9]{2}).(?P<minutes>[0-9]{2})")
  43
  44 class ParseError(Exception):
  45     """Raised when there is a problem parsing a date string"""
  46
  47 # Yoinked from python docs
  48 ZERO = timedelta(0)
  49 class Utc(tzinfo):
  50     """UTC
  51
  52     """
  53     def utcoffset(self, dt):
  54         return ZERO
  55
  56     def tzname(self, dt):
  57         return "UTC"
  58
  59     def dst(self, dt):
  60         return ZERO
  61 UTC = Utc()
  62
  63 class FixedOffset(tzinfo):
  64     """Fixed offset in hours and minutes from UTC
  65
  66     """
  67     def __init__(self, offset_hours, offset_minutes, name):
  68         self.__offset = timedelta(hours=offset_hours, minutes=offset_minutes)
  69         self.__name = name
  70
  71     def utcoffset(self, dt):
  72         return self.__offset
  73
  74     def tzname(self, dt):
  75         return self.__name
  76
  77     def dst(self, dt):
  78         return ZERO
  79
  80     def __repr__(self):
  81         return "<FixedOffset %r>" % self.__name
  82
  83 def parse_timezone(tzstring, default_timezone=UTC):
  84     """Parses ISO 8601 time zone specs into tzinfo offsets
  85
  86     """
  87     if tzstring == "Z":
  88         return default_timezone
  89     # This isn't strictly correct, but it's common to encounter dates without
  90     # timezones so I'll assume the default (which defaults to UTC).
  91     # Addresses issue 4.
  92     if tzstring is None:
  93         return default_timezone
  94     m = TIMEZONE_REGEX.match(tzstring)
  95     prefix, hours, minutes = m.groups()
  96     hours, minutes = int(hours), int(minutes)
  97     if prefix == "-":
  98         hours = -hours
  99         minutes = -minutes
 100     return FixedOffset(hours, minutes, tzstring)
 101
 102 def parse_date(datestring, default_timezone=UTC):
 103     """Parses ISO 8601 dates into datetime objects
 104
 105     The timezone is parsed from the date string. However it is quite common to
 106     have dates without a timezone (not strictly correct). In this case the
 107     default timezone specified in default_timezone is used. This is UTC by
 108     default.
 109     """
 110     if not isinstance(datestring, basestring):
 111         raise ParseError("Expecting a string %r" % datestring)
 112     m = ISO8601_REGEX.match(datestring)
 113     if not m:
 114         raise ParseError("Unable to parse date string %r" % datestring)
 115     groups = m.groupdict()
 116     tz = parse_timezone(groups["timezone"], default_timezone=default_timezone)
 117     if groups["fraction"] is None:
 118         groups["fraction"] = 0
 119     else:
 120         groups["fraction"] = int(float("0.%s" % groups["fraction"]) * 1e6)
 121     return datetime(int(groups["year"]), int(groups["month"]), int(groups["day"]),
 122         int(groups["hour"]), int(groups["minute"]), int(groups["second"]),
 123         int(groups["fraction"]), tz)