159 lines
7.0 KiB
Python
159 lines
7.0 KiB
Python
##############################################################################
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# Copyright 2009, Gerhard Weis
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions are met:
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#
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# * Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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# * Neither the name of the authors nor the names of its contributors
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# may be used to endorse or promote products derived from this software
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# without specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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# CONTRACT, STRICT LIABILITY, OR TORT
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##############################################################################
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'''
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This modules provides a method to parse an ISO 8601:2004 time string to a
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Python datetime.time instance.
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It supports all basic and extended formats including time zone specifications
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as described in the ISO standard.
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'''
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import re
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from decimal import Decimal
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from datetime import time
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from isodate.isostrf import strftime, TIME_EXT_COMPLETE, TZ_EXT
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from isodate.isoerror import ISO8601Error
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from isodate.isotzinfo import TZ_REGEX, build_tzinfo
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TIME_REGEX_CACHE = []
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# used to cache regular expressions to parse ISO time strings.
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def build_time_regexps():
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'''
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Build regular expressions to parse ISO time string.
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The regular expressions are compiled and stored in TIME_REGEX_CACHE
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for later reuse.
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'''
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if not TIME_REGEX_CACHE:
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# ISO 8601 time representations allow decimal fractions on least
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# significant time component. Command and Full Stop are both valid
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# fraction separators.
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# The letter 'T' is allowed as time designator in front of a time
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# expression.
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# Immediately after a time expression, a time zone definition is
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# allowed.
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# a TZ may be missing (local time), be a 'Z' for UTC or a string of
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# +-hh:mm where the ':mm' part can be skipped.
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# TZ information patterns:
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# ''
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# Z
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# +-hh:mm
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# +-hhmm
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# +-hh =>
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# isotzinfo.TZ_REGEX
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# 1. complete time:
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# hh:mm:ss.ss ... extended format
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TIME_REGEX_CACHE.append(re.compile(r"T?(?P<hour>[0-9]{2}):"
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r"(?P<minute>[0-9]{2}):"
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r"(?P<second>[0-9]{2}"
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r"([,.][0-9]+)?)" + TZ_REGEX))
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# hhmmss.ss ... basic format
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TIME_REGEX_CACHE.append(re.compile(r"T?(?P<hour>[0-9]{2})"
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r"(?P<minute>[0-9]{2})"
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r"(?P<second>[0-9]{2}"
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r"([,.][0-9]+)?)" + TZ_REGEX))
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# 2. reduced accuracy:
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# hh:mm.mm ... extended format
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TIME_REGEX_CACHE.append(re.compile(r"T?(?P<hour>[0-9]{2}):"
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r"(?P<minute>[0-9]{2}"
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r"([,.][0-9]+)?)" + TZ_REGEX))
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# hhmm.mm ... basic format
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TIME_REGEX_CACHE.append(re.compile(r"T?(?P<hour>[0-9]{2})"
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r"(?P<minute>[0-9]{2}"
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r"([,.][0-9]+)?)" + TZ_REGEX))
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# hh.hh ... basic format
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TIME_REGEX_CACHE.append(re.compile(r"T?(?P<hour>[0-9]{2}"
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r"([,.][0-9]+)?)" + TZ_REGEX))
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return TIME_REGEX_CACHE
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def parse_time(timestring):
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'''
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Parses ISO 8601 times into datetime.time objects.
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Following ISO 8601 formats are supported:
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(as decimal separator a ',' or a '.' is allowed)
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hhmmss.ssTZD basic complete time
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hh:mm:ss.ssTZD extended compelte time
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hhmm.mmTZD basic reduced accuracy time
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hh:mm.mmTZD extended reduced accuracy time
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hh.hhTZD basic reduced accuracy time
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TZD is the time zone designator which can be in the following format:
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no designator indicates local time zone
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Z UTC
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+-hhmm basic hours and minutes
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+-hh:mm extended hours and minutes
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+-hh hours
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'''
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isotimes = build_time_regexps()
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for pattern in isotimes:
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match = pattern.match(timestring)
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if match:
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groups = match.groupdict()
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for key, value in groups.items():
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if value is not None:
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groups[key] = value.replace(',', '.')
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tzinfo = build_tzinfo(groups['tzname'], groups['tzsign'],
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int(groups['tzhour'] or 0),
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int(groups['tzmin'] or 0))
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if 'second' in groups:
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# round to microseconds if fractional seconds are more precise
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second = Decimal(groups['second']).quantize(Decimal('.000001'))
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microsecond = (second - int(second)) * int(1e6)
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# int(...) ... no rounding
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# to_integral() ... rounding
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return time(int(groups['hour']), int(groups['minute']),
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int(second), int(microsecond.to_integral()),
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tzinfo)
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if 'minute' in groups:
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minute = Decimal(groups['minute'])
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second = (minute - int(minute)) * 60
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microsecond = (second - int(second)) * int(1e6)
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return time(int(groups['hour']), int(minute), int(second),
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int(microsecond.to_integral()), tzinfo)
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else:
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microsecond, second, minute = 0, 0, 0
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hour = Decimal(groups['hour'])
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minute = (hour - int(hour)) * 60
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second = (minute - int(minute)) * 60
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microsecond = (second - int(second)) * int(1e6)
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return time(int(hour), int(minute), int(second),
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int(microsecond.to_integral()), tzinfo)
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raise ISO8601Error('Unrecognised ISO 8601 time format: %r' % timestring)
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def time_isoformat(ttime, format=TIME_EXT_COMPLETE + TZ_EXT):
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'''
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Format time strings.
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This method is just a wrapper around isodate.isostrf.strftime and uses
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Time-Extended-Complete with extended time zone as default format.
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'''
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return strftime(ttime, format)
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