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- """
- This module provides an ISO 8601:2004 time zone info parser.
- It offers a function to parse the time zone offset as specified by ISO 8601.
- """
- import re
- from isodate.isoerror import ISO8601Error
- from isodate.tzinfo import UTC, ZERO, FixedOffset
- TZ_REGEX = (
- r"(?P<tzname>(Z|(?P<tzsign>[+-])" r"(?P<tzhour>[0-9]{2})(:?(?P<tzmin>[0-9]{2}))?)?)"
- )
- TZ_RE = re.compile(TZ_REGEX)
- def build_tzinfo(tzname, tzsign="+", tzhour=0, tzmin=0):
- """
- create a tzinfo instance according to given parameters.
- tzname:
- 'Z' ... return UTC
- '' | None ... return None
- other ... return FixedOffset
- """
- if tzname is None or tzname == "":
- return None
- if tzname == "Z":
- return UTC
- tzsign = ((tzsign == "-") and -1) or 1
- return FixedOffset(tzsign * tzhour, tzsign * tzmin, tzname)
- def parse_tzinfo(tzstring):
- """
- Parses ISO 8601 time zone designators to tzinfo objects.
- A time zone designator can be in the following format:
- no designator indicates local time zone
- Z UTC
- +-hhmm basic hours and minutes
- +-hh:mm extended hours and minutes
- +-hh hours
- """
- match = TZ_RE.match(tzstring)
- if match:
- groups = match.groupdict()
- return build_tzinfo(
- groups["tzname"],
- groups["tzsign"],
- int(groups["tzhour"] or 0),
- int(groups["tzmin"] or 0),
- )
- raise ISO8601Error("%s not a valid time zone info" % tzstring)
- def tz_isoformat(dt, format="%Z"):
- """
- return time zone offset ISO 8601 formatted.
- The various ISO formats can be chosen with the format parameter.
- if tzinfo is None returns ''
- if tzinfo is UTC returns 'Z'
- else the offset is rendered to the given format.
- format:
- %h ... +-HH
- %z ... +-HHMM
- %Z ... +-HH:MM
- """
- tzinfo = dt.tzinfo
- if (tzinfo is None) or (tzinfo.utcoffset(dt) is None):
- return ""
- if tzinfo.utcoffset(dt) == ZERO and tzinfo.dst(dt) == ZERO:
- return "Z"
- tdelta = tzinfo.utcoffset(dt)
- seconds = tdelta.days * 24 * 60 * 60 + tdelta.seconds
- sign = ((seconds < 0) and "-") or "+"
- seconds = abs(seconds)
- minutes, seconds = divmod(seconds, 60)
- hours, minutes = divmod(minutes, 60)
- if hours > 99:
- raise OverflowError("can not handle differences > 99 hours")
- if format == "%Z":
- return "%s%02d:%02d" % (sign, hours, minutes)
- elif format == "%z":
- return "%s%02d%02d" % (sign, hours, minutes)
- elif format == "%h":
- return "%s%02d" % (sign, hours)
- raise ValueError('unknown format string "%s"' % format)
|
