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ruby--ruby/lib/time.rb
Jeremy Evans a9d4f2d03c Support %U/%u/%W/%w/%V/%g/%G formats in Time.strptime
Most of these formats were documented as supported, but were not
actually supported. Document that %g and %G are supported.

If %U/%W is specified without yday and mon/mday are not specified,
then Date.strptime is used to get the appropriate yday.

If cwyear is specifier without the year, or cwday and cweek are
specified without mday and mon, then use Date.strptime and convert
the resulting value to Time, since Time.make_time cannot handle
those conversions

Fixes [Bug #9836]
Fixes [Bug #14241]
2019-11-21 03:32:20 +02:00

740 lines
24 KiB
Ruby

# frozen_string_literal: true
require 'date'
# :stopdoc:
# = time.rb
#
# When 'time' is required, Time is extended with additional methods for parsing
# and converting Times.
#
# == Features
#
# This library extends the Time class with the following conversions between
# date strings and Time objects:
#
# * date-time defined by {RFC 2822}[http://www.ietf.org/rfc/rfc2822.txt]
# * HTTP-date defined by {RFC 2616}[http://www.ietf.org/rfc/rfc2616.txt]
# * dateTime defined by XML Schema Part 2: Datatypes ({ISO
# 8601}[http://www.iso.org/iso/date_and_time_format])
# * various formats handled by Date._parse
# * custom formats handled by Date._strptime
# :startdoc:
class Time
class << Time
#
# A hash of timezones mapped to hour differences from UTC. The
# set of time zones corresponds to the ones specified by RFC 2822
# and ISO 8601.
#
ZoneOffset = { # :nodoc:
'UTC' => 0,
# ISO 8601
'Z' => 0,
# RFC 822
'UT' => 0, 'GMT' => 0,
'EST' => -5, 'EDT' => -4,
'CST' => -6, 'CDT' => -5,
'MST' => -7, 'MDT' => -6,
'PST' => -8, 'PDT' => -7,
# Following definition of military zones is original one.
# See RFC 1123 and RFC 2822 for the error in RFC 822.
'A' => +1, 'B' => +2, 'C' => +3, 'D' => +4, 'E' => +5, 'F' => +6,
'G' => +7, 'H' => +8, 'I' => +9, 'K' => +10, 'L' => +11, 'M' => +12,
'N' => -1, 'O' => -2, 'P' => -3, 'Q' => -4, 'R' => -5, 'S' => -6,
'T' => -7, 'U' => -8, 'V' => -9, 'W' => -10, 'X' => -11, 'Y' => -12,
}
#
# Return the number of seconds the specified time zone differs
# from UTC.
#
# Numeric time zones that include minutes, such as
# <code>-10:00</code> or <code>+1330</code> will work, as will
# simpler hour-only time zones like <code>-10</code> or
# <code>+13</code>.
#
# Textual time zones listed in ZoneOffset are also supported.
#
# If the time zone does not match any of the above, +zone_offset+
# will check if the local time zone (both with and without
# potential Daylight Saving \Time changes being in effect) matches
# +zone+. Specifying a value for +year+ will change the year used
# to find the local time zone.
#
# If +zone_offset+ is unable to determine the offset, nil will be
# returned.
#
# require 'time'
#
# Time.zone_offset("EST") #=> -18000
#
# You must require 'time' to use this method.
#
def zone_offset(zone, year=self.now.year)
off = nil
zone = zone.upcase
if /\A([+-])(\d\d)(:?)(\d\d)(?:\3(\d\d))?\z/ =~ zone
off = ($1 == '-' ? -1 : 1) * (($2.to_i * 60 + $4.to_i) * 60 + $5.to_i)
elsif zone.match?(/\A[+-]\d\d\z/)
off = zone.to_i * 3600
elsif ZoneOffset.include?(zone)
off = ZoneOffset[zone] * 3600
elsif ((t = self.local(year, 1, 1)).zone.upcase == zone rescue false)
off = t.utc_offset
elsif ((t = self.local(year, 7, 1)).zone.upcase == zone rescue false)
off = t.utc_offset
end
off
end
def zone_utc?(zone)
# * +0000
# In RFC 2822, +0000 indicate a time zone at Universal Time.
# Europe/Lisbon is "a time zone at Universal Time" in Winter.
# Atlantic/Reykjavik is "a time zone at Universal Time".
# Africa/Dakar is "a time zone at Universal Time".
# So +0000 is a local time such as Europe/London, etc.
# * GMT
# GMT is used as a time zone abbreviation in Europe/London,
# Africa/Dakar, etc.
# So it is a local time.
#
# * -0000, -00:00
# In RFC 2822, -0000 the date-time contains no information about the
# local time zone.
# In RFC 3339, -00:00 is used for the time in UTC is known,
# but the offset to local time is unknown.
# They are not appropriate for specific time zone such as
# Europe/London because time zone neutral,
# So -00:00 and -0000 are treated as UTC.
zone.match?(/\A(?:-00:00|-0000|-00|UTC|Z|UT)\z/i)
end
private :zone_utc?
def force_zone!(t, zone, offset=nil)
if zone_utc?(zone)
t.utc
elsif offset ||= zone_offset(zone)
# Prefer the local timezone over the fixed offset timezone because
# the former is a real timezone and latter is an artificial timezone.
t.localtime
if t.utc_offset != offset
# Use the fixed offset timezone only if the local timezone cannot
# represent the given offset.
t.localtime(offset)
end
else
t.localtime
end
end
private :force_zone!
LeapYearMonthDays = [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] # :nodoc:
CommonYearMonthDays = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31] # :nodoc:
def month_days(y, m)
if ((y % 4 == 0) && (y % 100 != 0)) || (y % 400 == 0)
LeapYearMonthDays[m-1]
else
CommonYearMonthDays[m-1]
end
end
private :month_days
def apply_offset(year, mon, day, hour, min, sec, off)
if off < 0
off = -off
off, o = off.divmod(60)
if o != 0 then sec += o; o, sec = sec.divmod(60); off += o end
off, o = off.divmod(60)
if o != 0 then min += o; o, min = min.divmod(60); off += o end
off, o = off.divmod(24)
if o != 0 then hour += o; o, hour = hour.divmod(24); off += o end
if off != 0
day += off
days = month_days(year, mon)
if days and days < day
mon += 1
if 12 < mon
mon = 1
year += 1
end
day = 1
end
end
elsif 0 < off
off, o = off.divmod(60)
if o != 0 then sec -= o; o, sec = sec.divmod(60); off -= o end
off, o = off.divmod(60)
if o != 0 then min -= o; o, min = min.divmod(60); off -= o end
off, o = off.divmod(24)
if o != 0 then hour -= o; o, hour = hour.divmod(24); off -= o end
if off != 0 then
day -= off
if day < 1
mon -= 1
if mon < 1
year -= 1
mon = 12
end
day = month_days(year, mon)
end
end
end
return year, mon, day, hour, min, sec
end
private :apply_offset
def make_time(date, year, yday, mon, day, hour, min, sec, sec_fraction, zone, now)
if !year && !yday && !mon && !day && !hour && !min && !sec && !sec_fraction
raise ArgumentError, "no time information in #{date.inspect}"
end
off = nil
if year || now
off_year = year || now.year
off = zone_offset(zone, off_year) if zone
end
if yday
unless (1..366) === yday
raise ArgumentError, "yday #{yday} out of range"
end
mon, day = (yday-1).divmod(31)
mon += 1
day += 1
t = make_time(date, year, nil, mon, day, hour, min, sec, sec_fraction, zone, now)
diff = yday - t.yday
return t if diff.zero?
day += diff
if day > 28 and day > (mday = month_days(off_year, mon))
if (mon += 1) > 12
raise ArgumentError, "yday #{yday} out of range"
end
day -= mday
end
return make_time(date, year, nil, mon, day, hour, min, sec, sec_fraction, zone, now)
end
if now and now.respond_to?(:getlocal)
if off
now = now.getlocal(off) if now.utc_offset != off
else
now = now.getlocal
end
end
usec = nil
usec = sec_fraction * 1000000 if sec_fraction
if now
begin
break if year; year = now.year
break if mon; mon = now.mon
break if day; day = now.day
break if hour; hour = now.hour
break if min; min = now.min
break if sec; sec = now.sec
break if sec_fraction; usec = now.tv_usec
end until true
end
year ||= 1970
mon ||= 1
day ||= 1
hour ||= 0
min ||= 0
sec ||= 0
usec ||= 0
if year != off_year
off = nil
off = zone_offset(zone, year) if zone
end
if off
year, mon, day, hour, min, sec =
apply_offset(year, mon, day, hour, min, sec, off)
t = self.utc(year, mon, day, hour, min, sec, usec)
force_zone!(t, zone, off)
t
else
self.local(year, mon, day, hour, min, sec, usec)
end
end
private :make_time
#
# Takes a string representation of a Time and attempts to parse it
# using a heuristic.
#
# require 'time'
#
# Time.parse("2010-10-31") #=> 2010-10-31 00:00:00 -0500
#
# Any missing pieces of the date are inferred based on the current date.
#
# require 'time'
#
# # assuming the current date is "2011-10-31"
# Time.parse("12:00") #=> 2011-10-31 12:00:00 -0500
#
# We can change the date used to infer our missing elements by passing a second
# object that responds to #mon, #day and #year, such as Date, Time or DateTime.
# We can also use our own object.
#
# require 'time'
#
# class MyDate
# attr_reader :mon, :day, :year
#
# def initialize(mon, day, year)
# @mon, @day, @year = mon, day, year
# end
# end
#
# d = Date.parse("2010-10-28")
# t = Time.parse("2010-10-29")
# dt = DateTime.parse("2010-10-30")
# md = MyDate.new(10,31,2010)
#
# Time.parse("12:00", d) #=> 2010-10-28 12:00:00 -0500
# Time.parse("12:00", t) #=> 2010-10-29 12:00:00 -0500
# Time.parse("12:00", dt) #=> 2010-10-30 12:00:00 -0500
# Time.parse("12:00", md) #=> 2010-10-31 12:00:00 -0500
#
# If a block is given, the year described in +date+ is converted
# by the block. This is specifically designed for handling two
# digit years. For example, if you wanted to treat all two digit
# years prior to 70 as the year 2000+ you could write this:
#
# require 'time'
#
# Time.parse("01-10-31") {|year| year + (year < 70 ? 2000 : 1900)}
# #=> 2001-10-31 00:00:00 -0500
# Time.parse("70-10-31") {|year| year + (year < 70 ? 2000 : 1900)}
# #=> 1970-10-31 00:00:00 -0500
#
# If the upper components of the given time are broken or missing, they are
# supplied with those of +now+. For the lower components, the minimum
# values (1 or 0) are assumed if broken or missing. For example:
#
# require 'time'
#
# # Suppose it is "Thu Nov 29 14:33:20 2001" now and
# # your time zone is EST which is GMT-5.
# now = Time.parse("Thu Nov 29 14:33:20 2001")
# Time.parse("16:30", now) #=> 2001-11-29 16:30:00 -0500
# Time.parse("7/23", now) #=> 2001-07-23 00:00:00 -0500
# Time.parse("Aug 31", now) #=> 2001-08-31 00:00:00 -0500
# Time.parse("Aug 2000", now) #=> 2000-08-01 00:00:00 -0500
#
# Since there are numerous conflicts among locally defined time zone
# abbreviations all over the world, this method is not intended to
# understand all of them. For example, the abbreviation "CST" is
# used variously as:
#
# -06:00 in America/Chicago,
# -05:00 in America/Havana,
# +08:00 in Asia/Harbin,
# +09:30 in Australia/Darwin,
# +10:30 in Australia/Adelaide,
# etc.
#
# Based on this fact, this method only understands the time zone
# abbreviations described in RFC 822 and the system time zone, in the
# order named. (i.e. a definition in RFC 822 overrides the system
# time zone definition.) The system time zone is taken from
# <tt>Time.local(year, 1, 1).zone</tt> and
# <tt>Time.local(year, 7, 1).zone</tt>.
# If the extracted time zone abbreviation does not match any of them,
# it is ignored and the given time is regarded as a local time.
#
# ArgumentError is raised if Date._parse cannot extract information from
# +date+ or if the Time class cannot represent specified date.
#
# This method can be used as a fail-safe for other parsing methods as:
#
# Time.rfc2822(date) rescue Time.parse(date)
# Time.httpdate(date) rescue Time.parse(date)
# Time.xmlschema(date) rescue Time.parse(date)
#
# A failure of Time.parse should be checked, though.
#
# You must require 'time' to use this method.
#
def parse(date, now=self.now)
comp = !block_given?
d = Date._parse(date, comp)
year = d[:year]
year = yield(year) if year && !comp
make_time(date, year, d[:yday], d[:mon], d[:mday], d[:hour], d[:min], d[:sec], d[:sec_fraction], d[:zone], now)
end
#
# Works similar to +parse+ except that instead of using a
# heuristic to detect the format of the input string, you provide
# a second argument that describes the format of the string.
#
# If a block is given, the year described in +date+ is converted by the
# block. For example:
#
# Time.strptime(...) {|y| y < 100 ? (y >= 69 ? y + 1900 : y + 2000) : y}
#
# Below is a list of the formatting options:
#
# %a :: The abbreviated weekday name ("Sun")
# %A :: The full weekday name ("Sunday")
# %b :: The abbreviated month name ("Jan")
# %B :: The full month name ("January")
# %c :: The preferred local date and time representation
# %C :: Century (20 in 2009)
# %d :: Day of the month (01..31)
# %D :: Date (%m/%d/%y)
# %e :: Day of the month, blank-padded ( 1..31)
# %F :: Equivalent to %Y-%m-%d (the ISO 8601 date format)
# %g :: The last two digits of the commercial year
# %G :: The week-based year according to ISO-8601 (week 1 starts on Monday
# and includes January 4)
# %h :: Equivalent to %b
# %H :: Hour of the day, 24-hour clock (00..23)
# %I :: Hour of the day, 12-hour clock (01..12)
# %j :: Day of the year (001..366)
# %k :: hour, 24-hour clock, blank-padded ( 0..23)
# %l :: hour, 12-hour clock, blank-padded ( 0..12)
# %L :: Millisecond of the second (000..999)
# %m :: Month of the year (01..12)
# %M :: Minute of the hour (00..59)
# %n :: Newline (\n)
# %N :: Fractional seconds digits
# %p :: Meridian indicator ("AM" or "PM")
# %P :: Meridian indicator ("am" or "pm")
# %r :: time, 12-hour (same as %I:%M:%S %p)
# %R :: time, 24-hour (%H:%M)
# %s :: Number of seconds since 1970-01-01 00:00:00 UTC.
# %S :: Second of the minute (00..60)
# %t :: Tab character (\t)
# %T :: time, 24-hour (%H:%M:%S)
# %u :: Day of the week as a decimal, Monday being 1. (1..7)
# %U :: Week number of the current year, starting with the first Sunday as
# the first day of the first week (00..53)
# %v :: VMS date (%e-%b-%Y)
# %V :: Week number of year according to ISO 8601 (01..53)
# %W :: Week number of the current year, starting with the first Monday
# as the first day of the first week (00..53)
# %w :: Day of the week (Sunday is 0, 0..6)
# %x :: Preferred representation for the date alone, no time
# %X :: Preferred representation for the time alone, no date
# %y :: Year without a century (00..99)
# %Y :: Year which may include century, if provided
# %z :: Time zone as hour offset from UTC (e.g. +0900)
# %Z :: Time zone name
# %% :: Literal "%" character
# %+ :: date(1) (%a %b %e %H:%M:%S %Z %Y)
#
# require 'time'
#
# Time.strptime("2000-10-31", "%Y-%m-%d") #=> 2000-10-31 00:00:00 -0500
#
# You must require 'time' to use this method.
#
def strptime(date, format, now=self.now)
d = Date._strptime(date, format)
raise ArgumentError, "invalid date or strptime format - `#{date}' `#{format}'" unless d
if seconds = d[:seconds]
if sec_fraction = d[:sec_fraction]
usec = sec_fraction * 1000000
usec *= -1 if seconds < 0
else
usec = 0
end
t = Time.at(seconds, usec)
if zone = d[:zone]
force_zone!(t, zone)
end
else
year = d[:year]
year = yield(year) if year && block_given?
yday = d[:yday]
if (d[:cwyear] && !year) || ((d[:cwday] || d[:cweek]) && !(d[:mon] && d[:mday]))
# make_time doesn't deal with cwyear/cwday/cweek
return Date.strptime(date, format).to_time
end
if (d[:wnum0] || d[:wnum1]) && !yday && !(d[:mon] && d[:mday])
yday = Date.strptime(date, format).yday
end
t = make_time(date, year, yday, d[:mon], d[:mday], d[:hour], d[:min], d[:sec], d[:sec_fraction], d[:zone], now)
end
t
end
MonthValue = { # :nodoc:
'JAN' => 1, 'FEB' => 2, 'MAR' => 3, 'APR' => 4, 'MAY' => 5, 'JUN' => 6,
'JUL' => 7, 'AUG' => 8, 'SEP' => 9, 'OCT' =>10, 'NOV' =>11, 'DEC' =>12
}
#
# Parses +date+ as date-time defined by RFC 2822 and converts it to a Time
# object. The format is identical to the date format defined by RFC 822 and
# updated by RFC 1123.
#
# ArgumentError is raised if +date+ is not compliant with RFC 2822
# or if the Time class cannot represent specified date.
#
# See #rfc2822 for more information on this format.
#
# require 'time'
#
# Time.rfc2822("Wed, 05 Oct 2011 22:26:12 -0400")
# #=> 2010-10-05 22:26:12 -0400
#
# You must require 'time' to use this method.
#
def rfc2822(date)
if /\A\s*
(?:(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun)\s*,\s*)?
(\d{1,2})\s+
(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\s+
(\d{2,})\s+
(\d{2})\s*
:\s*(\d{2})\s*
(?::\s*(\d{2}))?\s+
([+-]\d{4}|
UT|GMT|EST|EDT|CST|CDT|MST|MDT|PST|PDT|[A-IK-Z])/ix =~ date
# Since RFC 2822 permit comments, the regexp has no right anchor.
day = $1.to_i
mon = MonthValue[$2.upcase]
year = $3.to_i
short_year_p = $3.length <= 3
hour = $4.to_i
min = $5.to_i
sec = $6 ? $6.to_i : 0
zone = $7
if short_year_p
# following year completion is compliant with RFC 2822.
year = if year < 50
2000 + year
else
1900 + year
end
end
off = zone_offset(zone)
year, mon, day, hour, min, sec =
apply_offset(year, mon, day, hour, min, sec, off)
t = self.utc(year, mon, day, hour, min, sec)
force_zone!(t, zone, off)
t
else
raise ArgumentError.new("not RFC 2822 compliant date: #{date.inspect}")
end
end
alias rfc822 rfc2822
#
# Parses +date+ as an HTTP-date defined by RFC 2616 and converts it to a
# Time object.
#
# ArgumentError is raised if +date+ is not compliant with RFC 2616 or if
# the Time class cannot represent specified date.
#
# See #httpdate for more information on this format.
#
# require 'time'
#
# Time.httpdate("Thu, 06 Oct 2011 02:26:12 GMT")
# #=> 2011-10-06 02:26:12 UTC
#
# You must require 'time' to use this method.
#
def httpdate(date)
if date.match?(/\A\s*
(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun),\x20
(\d{2})\x20
(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\x20
(\d{4})\x20
(\d{2}):(\d{2}):(\d{2})\x20
GMT
\s*\z/ix)
self.rfc2822(date).utc
elsif /\A\s*
(?:Monday|Tuesday|Wednesday|Thursday|Friday|Saturday|Sunday),\x20
(\d\d)-(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)-(\d\d)\x20
(\d\d):(\d\d):(\d\d)\x20
GMT
\s*\z/ix =~ date
year = $3.to_i
if year < 50
year += 2000
else
year += 1900
end
self.utc(year, $2, $1.to_i, $4.to_i, $5.to_i, $6.to_i)
elsif /\A\s*
(?:Mon|Tue|Wed|Thu|Fri|Sat|Sun)\x20
(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\x20
(\d\d|\x20\d)\x20
(\d\d):(\d\d):(\d\d)\x20
(\d{4})
\s*\z/ix =~ date
self.utc($6.to_i, MonthValue[$1.upcase], $2.to_i,
$3.to_i, $4.to_i, $5.to_i)
else
raise ArgumentError.new("not RFC 2616 compliant date: #{date.inspect}")
end
end
#
# Parses +date+ as a dateTime defined by the XML Schema and converts it to
# a Time object. The format is a restricted version of the format defined
# by ISO 8601.
#
# ArgumentError is raised if +date+ is not compliant with the format or if
# the Time class cannot represent specified date.
#
# See #xmlschema for more information on this format.
#
# require 'time'
#
# Time.xmlschema("2011-10-05T22:26:12-04:00")
# #=> 2011-10-05 22:26:12-04:00
#
# You must require 'time' to use this method.
#
def xmlschema(date)
if /\A\s*
(-?\d+)-(\d\d)-(\d\d)
T
(\d\d):(\d\d):(\d\d)
(\.\d+)?
(Z|[+-]\d\d(?::?\d\d)?)?
\s*\z/ix =~ date
year = $1.to_i
mon = $2.to_i
day = $3.to_i
hour = $4.to_i
min = $5.to_i
sec = $6.to_i
usec = 0
if $7
usec = Rational($7) * 1000000
end
if $8
zone = $8
off = zone_offset(zone)
year, mon, day, hour, min, sec =
apply_offset(year, mon, day, hour, min, sec, off)
t = self.utc(year, mon, day, hour, min, sec, usec)
force_zone!(t, zone, off)
t
else
self.local(year, mon, day, hour, min, sec, usec)
end
else
raise ArgumentError.new("invalid date: #{date.inspect}")
end
end
alias iso8601 xmlschema
end # class << self
#
# Returns a string which represents the time as date-time defined by RFC 2822:
#
# day-of-week, DD month-name CCYY hh:mm:ss zone
#
# where zone is [+-]hhmm.
#
# If +self+ is a UTC time, -0000 is used as zone.
#
# require 'time'
#
# t = Time.now
# t.rfc2822 # => "Wed, 05 Oct 2011 22:26:12 -0400"
#
# You must require 'time' to use this method.
#
def rfc2822
sprintf('%s, %02d %s %0*d %02d:%02d:%02d ',
RFC2822_DAY_NAME[wday],
day, RFC2822_MONTH_NAME[mon-1], year < 0 ? 5 : 4, year,
hour, min, sec) <<
if utc?
'-0000'
else
off = utc_offset
sign = off < 0 ? '-' : '+'
sprintf('%s%02d%02d', sign, *(off.abs / 60).divmod(60))
end
end
alias rfc822 rfc2822
RFC2822_DAY_NAME = [ # :nodoc:
'Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'
]
RFC2822_MONTH_NAME = [ # :nodoc:
'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun',
'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'
]
#
# Returns a string which represents the time as RFC 1123 date of HTTP-date
# defined by RFC 2616:
#
# day-of-week, DD month-name CCYY hh:mm:ss GMT
#
# Note that the result is always UTC (GMT).
#
# require 'time'
#
# t = Time.now
# t.httpdate # => "Thu, 06 Oct 2011 02:26:12 GMT"
#
# You must require 'time' to use this method.
#
def httpdate
t = dup.utc
sprintf('%s, %02d %s %0*d %02d:%02d:%02d GMT',
RFC2822_DAY_NAME[t.wday],
t.day, RFC2822_MONTH_NAME[t.mon-1], t.year < 0 ? 5 : 4, t.year,
t.hour, t.min, t.sec)
end
#
# Returns a string which represents the time as a dateTime defined by XML
# Schema:
#
# CCYY-MM-DDThh:mm:ssTZD
# CCYY-MM-DDThh:mm:ss.sssTZD
#
# where TZD is Z or [+-]hh:mm.
#
# If self is a UTC time, Z is used as TZD. [+-]hh:mm is used otherwise.
#
# +fractional_digits+ specifies a number of digits to use for fractional
# seconds. Its default value is 0.
#
# require 'time'
#
# t = Time.now
# t.iso8601 # => "2011-10-05T22:26:12-04:00"
#
# You must require 'time' to use this method.
#
def xmlschema(fraction_digits=0)
fraction_digits = fraction_digits.to_i
s = strftime("%FT%T")
if fraction_digits > 0
s << strftime(".%#{fraction_digits}N")
end
s << (utc? ? 'Z' : strftime("%:z"))
end
alias iso8601 xmlschema
end