460 lines
14 KiB
Python
460 lines
14 KiB
Python
"""Python backwards-compat., date/time routines, seekable file object wrapper.
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Copyright 2002-2003 John J Lee <jjl@pobox.com>
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This code is free software; you can redistribute it and/or modify it under
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the terms of the BSD License (see the file COPYING included with the
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distribution).
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"""
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try: True
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except NameError:
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True = 1
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False = 0
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import re, string, time
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from types import TupleType
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from StringIO import StringIO
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try:
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from exceptions import StopIteration
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except ImportError:
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from ClientCookie._ClientCookie import StopIteration
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def startswith(string, initial):
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if len(initial) > len(string): return False
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return string[:len(initial)] == initial
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def endswith(string, final):
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if len(final) > len(string): return False
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return string[-len(final):] == final
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def compat_issubclass(obj, tuple_or_class):
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# for 2.1 and below
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if type(tuple_or_class) == TupleType:
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for klass in tuple_or_class:
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if issubclass(obj, klass):
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return True
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return False
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return issubclass(obj, tuple_or_class)
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def isstringlike(x):
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try: x+""
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except: return False
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else: return True
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try:
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from calendar import timegm
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timegm((2045, 1, 1, 22, 23, 32)) # overflows in 2.1
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except:
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# Number of days per month (except for February in leap years)
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mdays = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
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# Return 1 for leap years, 0 for non-leap years
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def isleap(year):
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return year % 4 == 0 and (year % 100 <> 0 or year % 400 == 0)
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# Return number of leap years in range [y1, y2)
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# Assume y1 <= y2 and no funny (non-leap century) years
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def leapdays(y1, y2):
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return (y2+3)/4 - (y1+3)/4
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EPOCH = 1970
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def timegm(tuple):
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"""Unrelated but handy function to calculate Unix timestamp from GMT."""
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year, month, day, hour, minute, second = tuple[:6]
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assert year >= EPOCH
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assert 1 <= month <= 12
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days = 365*(year-EPOCH) + leapdays(EPOCH, year)
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for i in range(1, month):
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days = days + mdays[i]
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if month > 2 and isleap(year):
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days = days + 1
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days = days + day - 1
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hours = days*24 + hour
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minutes = hours*60 + minute
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seconds = minutes*60L + second
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return seconds
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# Date/time conversion routines for formats used by the HTTP protocol.
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EPOCH = 1970
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def my_timegm(tt):
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year, month, mday, hour, min, sec = tt[:6]
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if ((year >= EPOCH) and (1 <= month <= 12) and (1 <= mday <= 31) and
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(0 <= hour <= 24) and (0 <= min <= 59) and (0 <= sec <= 61)):
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return timegm(tt)
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else:
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return None
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days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
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months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun",
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"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]
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months_lower = []
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for month in months: months_lower.append(string.lower(month))
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def time2isoz(t=None):
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"""Return a string representing time in seconds since epoch, t.
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If the function is called without an argument, it will use the current
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time.
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The format of the returned string is like "YYYY-MM-DD hh:mm:ssZ",
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representing Universal Time (UTC, aka GMT). An example of this format is:
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1994-11-24 08:49:37Z
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"""
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if t is None: t = time.time()
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year, mon, mday, hour, min, sec = time.gmtime(t)[:6]
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return "%04d-%02d-%02d %02d:%02d:%02dZ" % (
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year, mon, mday, hour, min, sec)
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def time2netscape(t=None):
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"""Return a string representing time in seconds since epoch, t.
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If the function is called without an argument, it will use the current
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time.
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The format of the returned string is like this:
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Wdy, DD-Mon-YYYY HH:MM:SS GMT
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"""
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if t is None: t = time.time()
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year, mon, mday, hour, min, sec, wday = time.gmtime(t)[:7]
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return "%s %02d-%s-%04d %02d:%02d:%02d GMT" % (
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days[wday], mday, months[mon-1], year, hour, min, sec)
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UTC_ZONES = {"GMT": None, "UTC": None, "UT": None, "Z": None}
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timezone_re = re.compile(r"^([-+])?(\d\d?):?(\d\d)?$")
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def offset_from_tz_string(tz):
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offset = None
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if UTC_ZONES.has_key(tz):
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offset = 0
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else:
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m = timezone_re.search(tz)
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if m:
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offset = 3600 * int(m.group(2))
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if m.group(3):
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offset = offset + 60 * int(m.group(3))
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if m.group(1) == '-':
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offset = -offset
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return offset
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def _str2time(day, mon, yr, hr, min, sec, tz):
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# translate month name to number
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# month numbers start with 1 (January)
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try:
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mon = months_lower.index(string.lower(mon))+1
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except ValueError:
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# maybe it's already a number
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try:
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imon = int(mon)
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except ValueError:
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return None
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if 1 <= imon <= 12:
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mon = imon
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else:
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return None
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# make sure clock elements are defined
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if hr is None: hr = 0
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if min is None: min = 0
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if sec is None: sec = 0
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yr = int(yr)
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day = int(day)
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hr = int(hr)
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min = int(min)
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sec = int(sec)
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if yr < 1000:
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# find "obvious" year
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cur_yr = time.localtime(time.time())[0]
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m = cur_yr % 100
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tmp = yr
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yr = yr + cur_yr - m
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m = m - tmp
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if abs(m) > 50:
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if m > 0: yr = yr + 100
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else: yr = yr - 100
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# convert UTC time tuple to seconds since epoch (not timezone-adjusted)
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t = my_timegm((yr, mon, day, hr, min, sec, tz))
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if t is not None:
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# adjust time using timezone string, to get absolute time since epoch
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if tz is None:
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tz = "UTC"
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tz = string.upper(tz)
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offset = offset_from_tz_string(tz)
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if offset is None:
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return None
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t = t - offset
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return t
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strict_re = re.compile(r"^[SMTWF][a-z][a-z], (\d\d) ([JFMASOND][a-z][a-z]) (\d\d\d\d) (\d\d):(\d\d):(\d\d) GMT$")
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wkday_re = re.compile(
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r"^(?:Sun|Mon|Tue|Wed|Thu|Fri|Sat)[a-z]*,?\s*", re.I)
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loose_http_re = re.compile(
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r"""^
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(\d\d?) # day
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(?:\s+|[-\/])
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(\w+) # month
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(?:\s+|[-\/])
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(\d+) # year
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(?:
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(?:\s+|:) # separator before clock
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(\d\d?):(\d\d) # hour:min
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(?::(\d\d))? # optional seconds
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)? # optional clock
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\s*
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([-+]?\d{2,4}|(?![APap][Mm]\b)[A-Za-z]+)? # timezone
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\s*
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(?:\(\w+\))? # ASCII representation of timezone in parens.
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\s*$""", re.X)
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def http2time(text):
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"""Returns time in seconds since epoch of time represented by a string.
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Return value is an integer.
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None is returned if the format of str is unrecognized, the time is outside
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the representable range, or the timezone string is not recognized. The
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time formats recognized are the same as for parse_date. If the string
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contains no timezone, UTC is assumed.
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The timezone in the string may be numerical (like "-0800" or "+0100") or a
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string timezone (like "UTC", "GMT", "BST" or "EST"). Currently, only the
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timezone strings equivalent to UTC (zero offset) are known to the function.
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The function loosely parses the following formats:
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Wed, 09 Feb 1994 22:23:32 GMT -- HTTP format
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Tuesday, 08-Feb-94 14:15:29 GMT -- old rfc850 HTTP format
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Tuesday, 08-Feb-1994 14:15:29 GMT -- broken rfc850 HTTP format
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09 Feb 1994 22:23:32 GMT -- HTTP format (no weekday)
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08-Feb-94 14:15:29 GMT -- rfc850 format (no weekday)
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08-Feb-1994 14:15:29 GMT -- broken rfc850 format (no weekday)
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The parser ignores leading and trailing whitespace. The time may be
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absent.
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If the year is given with only 2 digits, then parse_date will select the
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century that makes the year closest to the current date.
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"""
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# fast exit for strictly conforming string
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m = strict_re.search(text)
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if m:
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g = m.groups()
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mon = months_lower.index(string.lower(g[1])) + 1
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tt = (int(g[2]), mon, int(g[0]),
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int(g[3]), int(g[4]), float(g[5]))
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return my_timegm(tt)
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# No, we need some messy parsing...
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# clean up
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text = string.lstrip(text)
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text = wkday_re.sub("", text, 1) # Useless weekday
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# tz is time zone specifier string
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day, mon, yr, hr, min, sec, tz = [None]*7
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# loose regexp parse
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m = loose_http_re.search(text)
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if m is not None:
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day, mon, yr, hr, min, sec, tz = m.groups()
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else:
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return None # bad format
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return _str2time(day, mon, yr, hr, min, sec, tz)
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iso_re = re.compile(
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"""^
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(\d{4}) # year
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[-\/]?
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(\d\d?) # numerical month
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[-\/]?
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(\d\d?) # day
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(?:
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(?:\s+|[-:Tt]) # separator before clock
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(\d\d?):?(\d\d) # hour:min
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(?::?(\d\d(?:\.\d*)?))? # optional seconds (and fractional)
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)? # optional clock
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\s*
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([-+]?\d\d?:?(:?\d\d)?
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|Z|z)? # timezone (Z is "zero meridian", i.e. GMT)
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\s*$""", re.X)
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def iso2time(text):
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"""
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As for httpstr2time, but parses the ISO 8601 formats:
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1994-02-03 14:15:29 -0100 -- ISO 8601 format
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1994-02-03 14:15:29 -- zone is optional
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1994-02-03 -- only date
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1994-02-03T14:15:29 -- Use T as separator
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19940203T141529Z -- ISO 8601 compact format
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19940203 -- only date
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"""
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# clean up
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text = string.lstrip(text)
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# tz is time zone specifier string
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day, mon, yr, hr, min, sec, tz = [None]*7
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# loose regexp parse
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m = iso_re.search(text)
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if m is not None:
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# XXX there's an extra bit of the timezone I'm ignoring here: is
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# this the right thing to do?
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yr, mon, day, hr, min, sec, tz, _ = m.groups()
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else:
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return None # bad format
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return _str2time(day, mon, yr, hr, min, sec, tz)
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# XXX Andrew Dalke kindly sent me a similar class in response to my request on
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# comp.lang.python, which I then proceeded to lose. I wrote this class
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# instead, but I think he's released his code publicly since, could pinch the
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# tests from it, at least...
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class seek_wrapper:
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"""Adds a seek method to a file object.
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This is only designed for seeking on readonly file-like objects.
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Wrapped file-like object must have a read method. The readline method is
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only supported if that method is present on the wrapped object. The
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readlines method is always supported. xreadlines and iteration are
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supported only for Python 2.2 and above.
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Public attribute: wrapped (the wrapped file object).
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WARNING: All other attributes of the wrapped object (ie. those that are not
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one of wrapped, read, readline, readlines, xreadlines, __iter__ and next)
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are passed through unaltered, which may or may not make sense for your
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particular file object.
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"""
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# General strategy is to check that cache is full enough, then delegate
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# everything to the cache (self._cache, which is a StringIO.StringIO
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# instance. Seems to be some cStringIO.StringIO problem on 1.5.2 -- I
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# get a StringOobject, with no readlines method.
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# Invariant: the end of the cache is always at the same place as the
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# end of the wrapped file:
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# self.wrapped.tell() == len(self._cache.getvalue())
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def __init__(self, wrapped):
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self.wrapped = wrapped
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self.__have_readline = hasattr(self.wrapped, "readline")
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self.__cache = StringIO()
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def __getattr__(self, name): return getattr(self.wrapped, name)
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def seek(self, offset, whence=0):
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# make sure we have read all data up to the point we are seeking to
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pos = self.__cache.tell()
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if whence == 0: # absolute
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to_read = offset - pos
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elif whence == 1: # relative to current position
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to_read = offset
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elif whence == 2: # relative to end of *wrapped* file
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# since we don't know yet where the end of that file is, we must
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# read everything
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to_read = None
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if to_read >= 0 or to_read is None:
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if to_read is None:
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self.__cache.write(self.wrapped.read())
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else:
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self.__cache.write(self.wrapped.read(to_read))
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self.__cache.seek(pos)
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return self.__cache.seek(offset, whence)
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def read(self, size=-1):
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pos = self.__cache.tell()
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self.__cache.seek(pos)
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end = len(self.__cache.getvalue())
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available = end - pos
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# enough data already cached?
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if size <= available and size != -1:
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return self.__cache.read(size)
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# no, so read sufficient data from wrapped file and cache it
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to_read = size - available
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assert to_read > 0 or size == -1
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self.__cache.seek(0, 2)
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if size == -1:
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self.__cache.write(self.wrapped.read())
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else:
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self.__cache.write(self.wrapped.read(to_read))
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self.__cache.seek(pos)
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return self.__cache.read(size)
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def readline(self, size=-1):
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if not self.__have_readline:
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raise NotImplementedError("no readline method on wrapped object")
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# line we're about to read might not be complete in the cache, so
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# read another line first
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pos = self.__cache.tell()
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self.__cache.seek(0, 2)
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self.__cache.write(self.wrapped.readline())
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self.__cache.seek(pos)
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data = self.__cache.readline()
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if size != -1:
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r = data[:size]
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self.__cache.seek(pos+size)
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else:
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r = data
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return r
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def readlines(self, sizehint=-1):
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pos = self.__cache.tell()
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self.__cache.seek(0, 2)
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self.__cache.write(self.wrapped.read())
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self.__cache.seek(pos)
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try:
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return self.__cache.readlines(sizehint)
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except TypeError: # 1.5.2 hack
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return self.__cache.readlines()
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def __iter__(self): return self
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def next(self):
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line = self.readline()
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if line == "": raise StopIteration
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return line
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xreadlines = __iter__
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def __repr__(self):
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return ("<%s at %s whose wrapped object = %s>" %
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(self.__class__.__name__, `id(self)`, `self.wrapped`))
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def close(self):
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self.read = None
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self.readline = None
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self.readlines = None
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self.seek = None
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if self.wrapped: self.wrapped.close()
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self.wrapped = None
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