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