Added a module which handles parsing of time strings which include timezone information, tzparse.py.
- Legacy-Id: 4975
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Henrik Levkowetz
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8aa4922978
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185
tzparse.py
Executable file
185
tzparse.py
Executable file
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#!/usr/bin/env python
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"""
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NAME
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tzparse
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SYNOPSIS
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>>> tzparse("2008-09-08 14:40:35 +0200", "%Y-%m-%d %H:%M:%S %Z")
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datetime.datetime(2008, 9, 8, 14, 40, 35, tzinfo=pytz.FixedOffset(120))
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>>> print tzparse("14:40:35 CEST, 08 Sep 2008", "%H:%M:%S %Z, %d %b %Y")
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2008-09-08 14:40:35+02:00
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DESCRIPTION
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This describes the python 'tzparse' module. It exports only one function: tzparse().
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tzparse() parses a string according to a specified format, exactly as time.strptime()
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does, but with the added capability to parse most common timezone specifications,
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such as 'UTC', the standard timezones ('NST', 'EST', 'CST', 'MST', 'PST', 'HNY'
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[North America], 'WET', 'CET', 'EET', 'MSK' [Europe], and more), the summer timezones
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('CEST', 'EEST', 'EDT', PDT' etc.), military timezones ('A' .. 'Z') and numeric
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timezone indications ('+0200', '-0700', '-03:30' etc.).
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The time zone specification may be placed anywhere, not only at the end.
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tzparse() calls time.strptime() to parse everything except the timezone. To parse
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the timezone, it first tries to use the pytz module, but if that doesn't give
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any joy, it falls back to a hardcoded list of common time zone abbreviations and
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their offset from UTC.
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BUGS
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* tzparse() cannot parse all valid RFC 3339 formats: it doesn't extract
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fractional seconds, and the underlying time.strptime() doesn't parse fractional
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seconds.
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* Parsing according to format specifications using the generic %c, %x and %X
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specifiers will only succeed if there are explicit delimiting characters
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between the %Z specifier and the %c, %x or %X part.
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COPYRIGHT
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Copyright 2009 Henrik Levkowetz
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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"""
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import re
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import time
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from datetime import datetime as Datetime, timedelta as Timedelta
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import pytz
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tzdef = {
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"A": "+0100", "ACDT": "+1030", "ACST": "+0930", "ADT": "-0300",
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"AEDT": "+1100", "AEST": "+1000", "AKDT": "-0800", "AKST": "-0900",
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"AST": "-0400", "AWDT": "+0900", "AWST": "+0800", "B": "+0200",
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"BST": "+0100", "C": "+0300", "CDT": "+1030", "CDT": "-0500",
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"CEDT": "+0200", "CEST": "+0200", "CET": "+0100", "CST": "+1030",
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"CST": "+0930", "CST": "-0600", "CXT": "+0700", "D": "+0400",
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"E": "+0500", "EDT": "+1100", "EDT": "-0400", "EEDT": "+0300",
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"EEST": "+0300", "EET": "+0200", "EST": "+1100", "EST": "+1000",
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"EST": "-0500", "F": "+0600", "G": "+0700", "GMT": "+0000",
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"H": "+0800", "HAA": "-0300", "HAC": "-0500", "HADT": "-0900",
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"HAE": "-0400", "HAP": "-0700", "HAR": "-0600", "HAST": "-1000",
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"HAT": "-0230", "HAY": "-0800", "HNA": "-0400", "HNC": "-0600",
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"HNE": "-0500", "HNP": "-0800", "HNR": "-0700", "HNT": "-0330",
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"HNY": "-0900", "I": "+0900", "IST": "+0100", "K": "+1000",
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"L": "+1100", "M": "+1200", "MDT": "-0600", "MESZ": "+0200",
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"MEZ": "+0100", "MSD": "+0400", "MSK": "+0300", "MST": "-0700",
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"N": "-0100", "NDT": "-0230", "NFT": "+1130", "NST": "-0330",
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"O": "-0200", "P": "-0300", "PDT": "-0700", "PST": "-0800",
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"Q": "-0400", "R": "-0500", "S": "-0600", "T": "-0700",
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"U": "-0800", "UTC": "+0000", "V": "-0900", "W": "-1000",
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"WDT": "+0900", "WEDT": "+0100", "WEST": "+0100", "WET": "+0000",
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"WST": "+0900", "WST": "+0800", "X": "-1100", "Y": "-1200",
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"Z": "+0000",
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}
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def tzparse(string, format):
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# It's surprising that there's no tz parsing capability in the python standard
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# library...
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"""
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Given a time specification string and a format, tzparse() returns a localized
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datetime.datetime.
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>>> print tzparse("9 Oct 2009 CEST 13:58", "%d %b %Y %Z %H:%M")
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2009-10-09 13:58:00+02:00
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>>> print tzparse("9 Oct 2009 13:58:00 Europe/Stockholm", "%d %b %Y %H:%M:%S %Z")
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2009-10-09 13:58:00+02:00
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>>> print tzparse("9 Oct 2009 13:58:00 +0200", "%d %b %Y %H:%M:%S %Z")
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2009-10-09 13:58:00+02:00
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>>> print tzparse("Fri, 9 Oct 2009 13:58:00 +0200", "%a, %d %b %Y %H:%M:%S %Z")
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2009-10-09 13:58:00+02:00
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>>> print tzparse("2009-10-09 13:58:00 EST", '%Y-%m-%d %H:%M:%S %Z')
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2009-10-09 13:58:00-05:00
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>>> print tzparse("2009-10-09 13:58:00+02:00", "%Y-%m-%d %H:%M:%S%Z")
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2009-10-09 13:58:00+02:00
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>>> print tzparse("1985-04-12T23:20:50Z", "%Y-%m-%dT%H:%M:%S%Z")
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1985-04-12 23:20:50+00:00
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>>> print tzparse("1996-12-19T16:39:57-08:00", "%Y-%m-%dT%H:%M:%S%Z")
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1996-12-19 16:39:57-08:00
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>>> print tzparse("1996-12-19T16:39:57", "%Y-%m-%dT%H:%M:%S")
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1996-12-19 16:39:57+01:00
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"""
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if not "%Z" in format:
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timetuple = time.strptime(string, format)
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tzstr = time.tzname[0]
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else:
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# extract the %Z part from the format and build a pattern to extract it
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# from the string, too.
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def fmt2pat(s):
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s = re.sub("%[dHIjmMSUwWyY]", "\d+", s)
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s = re.sub("%[aAbBp]", "\w+", s)
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s = re.sub("%[cxX]", ".+", s)
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s = s.replace("%%", "%")
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return s
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frontfmt, backfmt = format.split("%Z")
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frontpat = "^" + fmt2pat(frontfmt)
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backpat = fmt2pat(backfmt) + "$"
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frontstr = re.search(frontpat, string) and re.search(frontpat, string).group(0) or ""
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backstr = re.search(backpat, string) and re.search(backpat, string).group(0) or ""
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tzstr = string.replace(frontstr, "").replace(backstr, "") # This will fail is backstr occurs twice
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timetuple = time.strptime(frontstr+backstr, frontfmt+backfmt)
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dt = Datetime(*timetuple[:6])
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if not tzstr:
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tzstr = time.tzname[0]
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#raise ValueError("No timezone string found in '%s', but format contained %Z: '%s'."%(string, format))
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try:
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tz = pytz.timezone(tzstr)
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except KeyError:
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if tzstr in tzdef:
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# if we know the offset of the abbreviation, fall back to that
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tzstr = tzdef[tzstr]
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if re.search("^[+-][0-9][0-9]:?[0-9][0-9]$", tzstr):
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if ":" in tzstr:
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tzstr = tzstr[:3]+tzstr[4:]
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# convert numeric timezone to minutes
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sign = tzstr[0]
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h = int(tzstr[1:3])
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m = h*60 + int(tzstr[3:5])
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if sign == "-":
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m = -m
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tz = pytz.FixedOffset(m)
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else:
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raise ValueError("Unknown timezone '%s'" % tzstr)
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dt = tz.localize(dt)
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return dt
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if __name__ == "__main__":
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import sys
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if len(sys.argv[1:]) == 2:
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print tzparse(sys.argv[1], sys.argv[2])
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else:
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print "Running module tests:\n"
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import doctest
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print doctest.testmod()
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