"""ISO-8601 date format support, sufficient for the profile defined in
<http://www.w3.org/TR/NOTE-datetime>.
The parser is more flexible on the input format than is required to support
the W3C profile, but all accepted date/time values are legal ISO 8601 dates.
The tostring() method only generates formatted dates that are conformant to
the profile.
This module was written by Fred L. Drake, Jr. <fdrake@acm.org>.
"""
__version__ = '1.0'
import string
import time
def parse(s):
"""Parse an ISO-8601 date/time string, returning the value in seconds
since the epoch."""
m = __datetime_rx.match(s)
if m is None or m.group() != s:
raise ValueError, "unknown or illegal ISO-8601 date format: " + `s`
gmt = __extract_date(m) + __extract_time(m) + (0, 0, 0)
return time.mktime(gmt) + __extract_tzd(m) - time.timezone
def parse_timezone(timezone):
"""Parse an ISO-8601 time zone designator, returning the value in seconds
relative to UTC."""
m = __tzd_rx.match(timezone)
if not m:
raise ValueError, "unknown timezone specifier: " + `timezone`
if m.group() != timezone:
raise ValueError, "unknown timezone specifier: " + `timezone`
return __extract_tzd(m)
def tostring(t, timezone=0):
"""Format a time in ISO-8601 format.
If `timezone' is specified, the time will be specified for that timezone,
otherwise for UTC.
Some effort is made to avoid adding text for the 'seconds' field, but
seconds are supported to the hundredths.
"""
if type(timezone) is type(''):
timezone = parse_timezone(timezone)
else:
timezone = int(timezone)
if timezone:
sign = (timezone < 0) and "+" or "-"
timezone = abs(timezone)
hours = timezone / (60 * 60)
minutes = (timezone % (60 * 60)) / 60
tzspecifier = "%c%02d:%02d" % (sign, hours, minutes)
else:
tzspecifier = "Z"
psecs = t - int(t)
t = time.gmtime(int(t) - timezone)
year, month, day, hours, minutes, seconds = t[:6]
if seconds or psecs:
if psecs:
psecs = int(round(psecs * 100))
f = "%4d-%02d-%02dT%02d:%02d:%02d.%02d%s"
v = (year, month, day, hours, minutes, seconds, psecs, tzspecifier)
else:
f = "%4d-%02d-%02dT%02d:%02d:%02d%s"
v = (year, month, day, hours, minutes, seconds, tzspecifier)
else:
f = "%4d-%02d-%02dT%02d:%02d%s"
v = (year, month, day, hours, minutes, tzspecifier)
return f % v
def ctime(t):
"""Similar to time.ctime(), but using ISO-8601 format."""
return tostring(t, time.timezone)
# Internal data and functions:
import re
__date_re = ("(?P<year>\d\d\d\d)"
"(?:(?P<dsep>-|)"
"(?:(?P<julian>\d\d\d)"
"|(?P<month>\d\d)(?:(?P=dsep)(?P<day>\d\d))?))?")
__tzd_re = "(?P<tzd>[-+](?P<tzdhours>\d\d)(?::?(?P<tzdminutes>\d\d))|Z)"
__tzd_rx = re.compile(__tzd_re)
__time_re = ("(?P<hours>\d\d)(?P<tsep>:|)(?P<minutes>\d\d)"
"(?:(?P=tsep)(?P<seconds>\d\d(?:[.,]\d+)?))?"
+ __tzd_re)
__datetime_re = "%s(?:T%s)?" % (__date_re, __time_re)
__datetime_rx = re.compile(__datetime_re)
del re
def __extract_date(m):
year = string.atoi(m.group("year"), 10)
julian = m.group("julian")
if julian:
return __find_julian(year, string.atoi(julian, 10))
month = string.atoi(m.group("month"), 10)
day = 1
if month is None:
month = 1
elif not 1 <= month <= 12:
raise ValueError, "illegal month number: " + m.group("month")
else:
day = m.group("day")
if day:
day = string.atoi(day)
if not 1 <= day <= 31:
raise ValueError, "illegal day number: " + m.group("day")
else:
day = 1
return year, month, day
def __extract_time(m):
if not m:
return 0, 0, 0
hours = m.group("hours")
if not hours:
return 0, 0, 0
hours = string.atoi(hours, 10)
if not 0 <= hours <= 23:
raise ValueError, "illegal hour number: " + m.group("hours")
minutes = string.atoi(m.group("minutes"), 10)
if not 0 <= minutes <= 59:
raise ValueError, "illegal minutes number: " + m.group("minutes")
seconds = m.group("seconds")
if seconds:
seconds = string.atof(seconds)
if not 0 <= seconds <= 59:
raise ValueError, "illegal seconds number: " + m.group("seconds")
else:
seconds = 0
return hours, minutes, seconds
def __extract_tzd(m):
"""Return the Time Zone Designator as an offset in seconds from UTC."""
if not m:
return 0
tzd = m.group("tzd")
if not tzd:
return 0
if tzd == "Z":
return 0
hours = string.atoi(m.group("tzdhours"), 10)
minutes = m.group("tzdminutes")
if minutes:
minutes = string.atoi(minutes, 10)
else:
minutes = 0
offset = (hours*60 + minutes) * 60
if tzd[0] == "+":
return -offset
return offset
def __find_julian(year, julian):
month = julian / 30 + 1
day = julian % 30 + 1
jday = None
while jday != julian:
t = time.mktime((year, month, day, 0, 0, 0, 0, 0, 0))
jday = time.gmtime(t)[-2]
diff = abs(jday - julian)
if jday > julian:
if diff < day:
day = day - diff
else:
month = month - 1
day = 31
elif jday < julian:
if day + diff < 28:
day = day + diff
else:
month = month + 1
return year, month, day
|