| Class | Date |
| In: |
date.rb
date/format.rb |
| Parent: | Object |
Class representing a date.
See the documentation to the file date.rb for an overview.
Internally, the date is represented as an Astronomical Julian Day Number, ajd. The Day of Calendar Reform, sg, is also stored, for conversions to other date formats. (There is also an of field for a time zone offset, but this is only for the use of the DateTime subclass.)
A new Date object is created using one of the object creation class methods named after the corresponding date format, and the arguments appropriate to that date format; for instance, Date::civil() (aliased to Date::new()) with year, month, and day-of-month, or Date::ordinal() with year and day-of-year. All of these object creation class methods also take the Day of Calendar Reform as an optional argument.
Date objects are immutable once created.
Once a Date has been created, date values can be retrieved for the different date formats supported using instance methods. For instance, mon() gives the Civil month, cwday() gives the Commercial day of the week, and yday() gives the Ordinal day of the year. Date values can be retrieved in any format, regardless of what format was used to create the Date instance.
The Date class includes the Comparable module, allowing date objects to be compared and sorted, ranges of dates to be created, and so forth.
| MONTHNAMES | = | [nil] + %w(January February March April May June July August September October November December) | Full month names, in English. Months count from 1 to 12; a month‘s numerical representation indexed into this array gives the name of that month (hence the first element is nil). | |
| DAYNAMES | = | %w(Sunday Monday Tuesday Wednesday Thursday Friday Saturday) | Full names of days of the week, in English. Days of the week count from 0 to 6 (except in the commercial week); a day‘s numerical representation indexed into this array gives the name of that day. | |
| ABBR_MONTHNAMES | = | [nil] + %w(Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec) | Abbreviated month names, in English. | |
| ABBR_DAYNAMES | = | %w(Sun Mon Tue Wed Thu Fri Sat) | Abbreviated day names, in English. | |
| ITALY | = | 2299161 | The Julian Day Number of the Day of Calendar Reform for Italy and the Catholic countries. | |
| ENGLAND | = | 2361222 | The Julian Day Number of the Day of Calendar Reform for England and her Colonies. | |
| JULIAN | = | Infinity.new | A constant used to indicate that a Date should always use the Julian calendar. | |
| GREGORIAN | = | -Infinity.new | A constant used to indicate that a Date should always use the Gregorian calendar. |
| gregorian_leap? | -> | leap? |
| new | -> | new! |
| valid_civil? | -> | valid_date? |
| civil | -> | new |
Load from Marshall format.
# File date.rb, line 1352 def self._load(str) a = Marshal.load(str) if a.size == 2 ajd, sg = a of = 0 ajd -= 1.to_r/2 else ajd, of, sg = a end new!(ajd, of, sg) end
# File date/format.rb, line 958 def self._parse(str, comp=false) str = str.dup e = Format::Bag.new e._comp = comp str.gsub!(/[^-+',.\/:0-9@a-z\x80-\xff]+/in, ' ') _parse_time(str, e) # || _parse_beat(str, e) _parse_day(str, e) _parse_eu(str, e) || _parse_us(str, e) || _parse_iso(str, e) || _parse_jis(str, e) || _parse_vms(str, e) || _parse_sla_us(str, e) || _parse_iso2(str, e) || _parse_year(str, e) || _parse_mon(str, e) || _parse_mday(str, e) || _parse_ddd(str, e) if str.sub!(/\b(bc\b|bce\b|b\.c\.|b\.c\.e\.)/in, ' ') if e.year e.year = -e.year + 1 end end if str.sub!(/\A\s*(\d{1,2})\s*\z/n, ' ') if e.hour && !e.mday v = $1.to_i if (1..31) === v e.mday = v end end if e.mday && !e.hour v = $1.to_i if (0..24) === v e.hour = v end end end if e._comp and e.year if e.year >= 0 and e.year <= 99 if e.year >= 69 e.year += 1900 else e.year += 2000 end end end e.offset ||= zone_to_diff(e.zone) if e.zone e.to_hash end
# File date/format.rb, line 581 def self._strptime(str, fmt='%F') e = Format::Bag.new return unless _strptime_i(str.dup, fmt, e) if e._cent if e.cwyear e.cwyear += e._cent * 100 end if e.year e. year += e._cent * 100 end end if e._merid if e.hour e.hour %= 12 e.hour += e._merid end end e.to_hash end
Convert an Astronomical Julian Day Number to an Astronomical Modified Julian Day Number.
# File date.rb, line 513 def self.ajd_to_amjd(ajd) ajd - 4800001.to_r/2 end
Convert an Astronomical Julian Day Number to a (civil) Julian Day Number.
ajd is the Astronomical Julian Day Number to convert. of is the offset from UTC as a fraction of a day (defaults to 0).
Returns the (civil) Julian Day Number as [day_number, fraction] where fraction is always 1/2.
# File date.rb, line 479 def self.ajd_to_jd(ajd, of=0) (ajd + of + 1.to_r/2).divmod(1) end
Convert an Astronomical Modified Julian Day Number to an Astronomical Julian Day Number.
# File date.rb, line 509 def self.amjd_to_ajd(amjd) amjd + 4800001.to_r/2 end
Create a new Date object for the Civil Date specified by year y, month m, and day-of-month d.
m and d can be negative, in which case they count backwards from the end of the year and the end of the month respectively. No wraparound is performed, however, and invalid values cause an ArgumentError to be raised. can be negative
y defaults to -4712, m to 1, and d to 1; this is Julian Day Number day 0.
sg specifies the Day of Calendar Reform.
# File date.rb, line 725 def self.civil(y=-4712, m=1, d=1, sg=ITALY) unless jd = valid_civil?(y, m, d, sg) raise ArgumentError, 'invalid date' end new!(jd_to_ajd(jd, 0, 0), 0, sg) end
Convert a Civil Date to a Julian Day Number. y, m, and d are the year, month, and day of the month. sg specifies the Day of Calendar Reform.
Returns the corresponding Julian Day Number.
# File date.rb, line 383 def self.civil_to_jd(y, m, d, sg=GREGORIAN) if m <= 2 y -= 1 m += 12 end a = (y / 100.0).floor b = 2 - a + (a / 4.0).floor jd = (365.25 * (y + 4716)).floor + (30.6001 * (m + 1)).floor + d + b - 1524 if julian?(jd, sg) jd -= b end jd end
Create a new Date object for the Commercial Date specified by year y, week-of-year w, and day-of-week d.
Monday is day-of-week 1; Sunday is day-of-week 7.
w and d can be negative, in which case they count backwards from the end of the year and the end of the week respectively. No wraparound is performed, however, and invalid values cause an ArgumentError to be raised.
y defaults to 1582, w to 41, and d to 5, the Day of Calendar Reform for Italy and the Catholic countries.
sg specifies the Day of Calendar Reform.
# File date.rb, line 748 def self.commercial(y=1582, w=41, d=5, sg=ITALY) unless jd = valid_commercial?(y, w, d, sg) raise ArgumentError, 'invalid date' end new!(jd_to_ajd(jd, 0, 0), 0, sg) end
Convert a Commercial Date to a Julian Day Number.
y, w, and d are the (commercial) year, week of the year, and day of the week of the Commercial Date to convert. sg specifies the Day of Calendar Reform.
# File date.rb, line 432 def self.commercial_to_jd(y, w, d, ns=GREGORIAN) jd = civil_to_jd(y, 1, 4, ns) (jd - (((jd - 1) + 1) % 7)) + 7 * (w - 1) + (d - 1) end
Convert a (civil) Julian Day Number to an Astronomical Julian Day Number.
jd is the Julian Day Number to convert, and fr is a fractional day. of is the offset from UTC as a fraction of a day (defaults to 0).
Returns the Astronomical Julian Day Number as a single numeric value.
# File date.rb, line 490 def self.jd_to_ajd(jd, fr, of=0) jd + fr - of - 1.to_r/2 end
Convert a Julian Day Number to a Civil Date. jd is the Julian Day Number. sg specifies the Day of Calendar Reform.
Returns the corresponding [year, month, day_of_month] as a three-element array.
# File date.rb, line 405 def self.jd_to_civil(jd, sg=GREGORIAN) if julian?(jd, sg) a = jd else x = ((jd - 1867216.25) / 36524.25).floor a = jd + 1 + x - (x / 4.0).floor end b = a + 1524 c = ((b - 122.1) / 365.25).floor d = (365.25 * c).floor e = ((b - d) / 30.6001).floor dom = b - d - (30.6001 * e).floor if e <= 13 m = e - 1 y = c - 4716 else m = e - 13 y = c - 4715 end return y, m, dom end
Convert a Julian Day Number to a Commercial Date
jd is the Julian Day Number to convert. sg specifies the Day of Calendar Reform.
Returns the corresponding Commercial Date as [commercial_year, week_of_year, day_of_week]
# File date.rb, line 446 def self.jd_to_commercial(jd, sg=GREGORIAN) ns = fix_style(jd, sg) a = jd_to_civil(jd - 3, ns)[0] y = if jd >= commercial_to_jd(a + 1, 1, 1, ns) then a + 1 else a end w = 1 + ((jd - commercial_to_jd(y, 1, 1, ns)) / 7).floor d = (jd + 1) % 7 d = 7 if d == 0 return y, w, d end
Convert a Julian Day Number to the number of days since the adoption of the Gregorian Calendar (in Italy).
# File date.rb, line 529 def self.jd_to_ld(jd) jd - 2299160 end
Convert a Julian Day Number to a Modified Julian Day Number.
# File date.rb, line 521 def self.jd_to_mjd(jd) jd - 2400001 end
Convert a Julian Day Number to an Ordinal Date.
jd is the Julian Day Number to convert. sg specifies the Day of Calendar Reform.
Returns the corresponding Ordinal Date as [year, day_of_year]
# File date.rb, line 372 def self.jd_to_ordinal(jd, sg=GREGORIAN) y = jd_to_civil(jd, sg)[0] doy = jd - civil_to_jd(y - 1, 12, 31, fix_style(jd, sg)) return y, doy end
Does a given Julian Day Number fall inside the old-style (Julian) calendar?
jd is the Julian Day Number in question. sg may be Date::GREGORIAN, in which case the answer is false; it may be Date::JULIAN, in which case the answer is true; or it may a number representing the Day of Calendar Reform. Date::ENGLAND and Date::ITALY are two possible such days.
# File date.rb, line 327 def self.julian? (jd, sg) case sg when Numeric jd < sg else if $VERBOSE warn("#{caller.shift.sub(/:in .*/, '')}: " \ "warning: do not use non-numerical object as julian day number anymore") end not sg end end
Convert a count of the number of days since the adoption of the Gregorian Calendar (in Italy) to a Julian Day Number.
# File date.rb, line 525 def self.ld_to_jd(ld) ld + 2299160 end
Convert a Modified Julian Day Number to a Julian Day Number.
# File date.rb, line 517 def self.mjd_to_jd(mjd) mjd + 2400001 end
NOTE this is the documentation for the method new!(). If you are reading this as the documentation for new(), that is because rdoc doesn‘t fully support the aliasing of the initialize() method. new() is in fact an alias for civil(): read the documentation for that method instead.
ajd is the Astronomical Julian Day Number. of is the offset from UTC as a fraction of a day. Both default to 0.
sg specifies the Day of Calendar Reform to use for this Date object.
Using one of the factory methods such as Date::civil is generally easier and safer.
# File date.rb, line 1016 def initialize(ajd=0, of=0, sg=ITALY) @ajd, @of, @sg = ajd, of, sg end
Create a new Date object from an Ordinal Date, specified by year y and day-of-year d. d can be negative, in which it counts backwards from the end of the year. No year wraparound is performed, however. An invalid value for d results in an ArgumentError being raised.
y defaults to -4712, and d to 1; this is Julian Day Number day 0.
sg specifies the Day of Calendar Reform.
# File date.rb, line 705 def self.ordinal(y=-4712, d=1, sg=ITALY) unless jd = valid_ordinal?(y, d, sg) raise ArgumentError, 'invalid date' end new!(jd_to_ajd(jd, 0, 0), 0, sg) end
Create a new Date object by parsing from a String, without specifying the format.
str is a String holding a date representation. comp specifies whether to interpret 2-digit years as 19XX (>= 69) or 20XX (< 69); the default is not to. The method will attempt to parse a date from the String using various heuristics; see _parse in date/format.rb for more details. If parsing fails, an ArgumentError will be raised.
The default str is ’-4712-01-01’; this is Julian Day Number day 0.
sg specifies the Day of Calendar Reform.
# File date.rb, line 973 def self.parse(str='-4712-01-01', comp=false, sg=ITALY) elem = _parse(str, comp) new_by_frags(elem, sg) end
Create a new Date object by parsing from a String according to a specified format.
str is a String holding a date representation. fmt is the format that the date is in. See date/format.rb for details on supported formats.
The default str is ’-4712-01-01’, and the default fmt is ’%F’, which means Year-Month-Day_of_Month. This gives Julian Day Number day 0.
sg specifies the Day of Calendar Reform.
An ArgumentError will be raised if str cannot be parsed.
# File date.rb, line 953 def self.strptime(str='-4712-01-01', fmt='%F', sg=ITALY) elem = _strptime(str, fmt) new_by_frags(elem, sg) end
Do year y, month m, and day-of-month d make a valid Civil Date? Returns the corresponding Julian Day Number if they do, nil if they don‘t.
m and d can be negative, in which case they count backwards from the end of the year and the end of the month respectively. No wraparound is performed, however, and invalid values cause an ArgumentError to be raised. A date falling in the period skipped in the Day of Calendar Reform adjustment is not valid.
sg specifies the Day of Calendar Reform.
# File date.rb, line 595 def self.valid_civil? (y, m, d, sg=ITALY) if m < 0 m += 13 end if d < 0 ny, nm = (y * 12 + m).divmod(12) nm, = (nm + 1).divmod(1) jd = civil_to_jd(ny, nm, d + 1, sg) ns = fix_style(jd, sg) return unless [y, m] == jd_to_civil(jd, sg)[0..1] return unless [ny, nm, 1] == jd_to_civil(jd - d, ns) else jd = civil_to_jd(y, m, d, sg) return unless [y, m, d] == jd_to_civil(jd, sg) end jd end
Do year y, week-of-year w, and day-of-week d make a valid Commercial Date? Returns the corresponding Julian Day Number if they do, nil if they don‘t.
Monday is day-of-week 1; Sunday is day-of-week 7.
w and d can be negative, in which case they count backwards from the end of the year and the end of the week respectively. No wraparound is performed, however, and invalid values cause an ArgumentError to be raised. A date falling in the period skipped in the Day of Calendar Reform adjustment is not valid.
sg specifies the Day of Calendar Reform.
# File date.rb, line 629 def self.valid_commercial? (y, w, d, sg=ITALY) if d < 0 d += 8 end if w < 0 ny, nw, nd = jd_to_commercial(commercial_to_jd(y + 1, 1, 1) + w * 7) return unless ny == y w = nw end jd = commercial_to_jd(y, w, d) return unless gregorian?(jd, sg) return unless [y, w, d] == jd_to_commercial(jd) jd end
Do the year y and day-of-year d make a valid Ordinal Date? Returns the corresponding Julian Day Number if they do, or nil if they don‘t.
d can be a negative number, in which case it counts backwards from the end of the year (-1 being the last day of the year). No year wraparound is performed, however, so valid values of d are -365 .. -1, 1 .. 365 on a non-leap-year, -366 .. -1, 1 .. 366 on a leap year. A date falling in the period skipped in the Day of Calendar Reform adjustment is not valid.
sg specifies the Day of Calendar Reform.
# File date.rb, line 569 def self.valid_ordinal? (y, d, sg=ITALY) if d < 0 ny, = (y + 1).divmod(1) jd = ordinal_to_jd(ny, d + 1, sg) ns = fix_style(jd, sg) return unless [y] == jd_to_ordinal(jd, sg)[0..0] return unless [ny, 1] == jd_to_ordinal(jd - d, ns) else jd = ordinal_to_jd(y, d, sg) return unless [y, d] == jd_to_ordinal(jd, sg) end jd end
Do hour h, minute min, and second s constitute a valid time?
If they do, returns their value as a fraction of a day. If not, returns nil.
The 24-hour clock is used. Negative values of h, min, and sec are treating as counting backwards from the end of the next larger unit (e.g. a min of -2 is treated as 58). No wraparound is performed.
# File date.rb, line 672 def self.valid_time? (h, min, s) h += 24 if h < 0 min += 60 if min < 0 s += 60 if s < 0 return unless ((0..23) === h && (0..59) === min && (0..59) === s) || (24 == h && 0 == min && 0 == s) time_to_day_fraction(h, min, s) end
Return a new Date object that is n days later than the current one.
n may be a negative value, in which case the new Date is earlier than the current one; however, #-() might be more intuitive.
If n is not a Numeric, a TypeError will be thrown. In particular, two Dates cannot be added to each other.
# File date.rb, line 1201 def + (n) case n when Numeric; return self.class.new!(@ajd + n, @of, @sg) end raise TypeError, 'expected numeric' end
If x is a Numeric value, create a new Date object that is x days earlier than the current one.
If x is a Date, return the number of days between the two dates; or, more precisely, how many days later the current date is than x.
If x is neither Numeric nor a Date, a TypeError is raised.
# File date.rb, line 1216 def - (x) case x when Numeric; return self.class.new!(@ajd - x, @of, @sg) when Date; return @ajd - x.ajd end raise TypeError, 'expected numeric or date' end
Return a new Date object that is n months earlier than the current one.
If the day-of-the-month of the current Date is greater than the last day of the target month, the day-of-the-month of the returned Date will be the last day of the target month.
# File date.rb, line 1287 def << (n) self >> -n end
Compare this date with another date.
other can also be a Numeric value, in which case it is interpreted as an Astronomical Julian Day Number.
Comparison is by Astronomical Julian Day Number, including fractional days. This means that both the time and the timezone offset are taken into account when comparing two DateTime instances. When comparing a DateTime instance with a Date instance, the time of the latter will be considered as falling on midnight UTC.
# File date.rb, line 1235 def <=> (other) case other when Numeric; return @ajd <=> other when Date; return @ajd <=> other.ajd end nil end
The relationship operator for Date.
Compares dates by Julian Day Number. When comparing two DateTime instances, or a DateTime with a Date, the instances will be regarded as equivalent if they fall on the same date in local time.
# File date.rb, line 1249 def === (other) case other when Numeric; return jd == other when Date; return jd == other.jd end false end
Return a new Date object that is n months later than the current one.
If the day-of-the-month of the current Date is greater than the last day of the target month, the day-of-the-month of the returned Date will be the last day of the target month.
# File date.rb, line 1273 def >> (n) y, m = (year * 12 + (mon - 1) + n).divmod(12) m, = (m + 1) .divmod(1) d = mday d -= 1 until jd2 = self.class.valid_civil?(y, m, d, fix_style) self + (jd2 - jd) end
Dump to Marshal format.
# File date.rb, line 1347 def _dump(limit) Marshal.dump([@ajd, @of, @sg], -1) end
Get the date as an Astronomical Modified Julian Day Number.
# File date.rb, line 1022 def amjd() self.class.ajd_to_amjd(@ajd) end
Get the commercial day of the week of this date. Monday is commercial day-of-week 1; Sunday is commercial day-of-week 7.
# File date.rb, line 1115 def cwday() commercial[2] end
Get the commercial week of the year of this date.
# File date.rb, line 1111 def cweek() commercial[1] end
Get the commercial year of this date. See Commercial Date in the introduction for how this differs from the normal year.
# File date.rb, line 1108 def cwyear() commercial[0] end