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.

### Methods

+ - << <=> === >> _dump _load _parse _strptime ajd ajd_to_amjd ajd_to_jd amjd amjd_to_ajd asctime civil civil_to_jd commercial commercial_to_jd ctime cwday cweek cwyear day day_fraction day_fraction_to_time downto england eql? gregorian gregorian_leap? hash inspect italy jd jd jd_to_ajd jd_to_civil jd_to_commercial jd_to_ld jd_to_mjd jd_to_ordinal jd_to_wday julian julian_leap? ld ld_to_jd leap? mday mjd mjd_to_jd mon month new new_start next ns? ns? ordinal ordinal_to_jd os? os? parse start step strftime strptime succ time_to_day_fraction to_s today upto valid_civil? valid_commercial? valid_jd? valid_ordinal? wday yday year zone_to_diff

### Included Modules

Comparable

### Constants

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 | = | false |  | A constant used to indicate that a Date should always use the Julian calendar.
GREGORIAN | = | true |  | A constant used to indicate that a Date should always use the Gregorian calendar.
MONTHS | = | { 'january' => 1, 'february' => 2, 'march' => 3, 'april' => 4, 'may' => 5, 'june' => 6, 'july' => 7, 'august' => 8, 'september'=> 9, 'october' =>10, 'november' =>11, 'december' =>12
DAYS | = | { 'sunday' => 0, 'monday' => 1, 'tuesday' => 2, 'wednesday'=> 3, 'thursday' => 4, 'friday' => 5, 'saturday' => 6
ABBR_MONTHS | = | { 'jan' => 1, 'feb' => 2, 'mar' => 3, 'apr' => 4, 'may' => 5, 'jun' => 6, 'jul' => 7, 'aug' => 8, 'sep' => 9, 'oct' =>10, 'nov' =>11, 'dec' =>12
ABBR_DAYS | = | { 'sun' => 0, 'mon' => 1, 'tue' => 2, 'wed' => 3, 'thu' => 4, 'fri' => 5, 'sat' => 6
ZONES | = | { 'ut' => 0*3600, 'gmt' => 0*3600, 'est' => -5*3600, 'edt' => -4*3600, 'cst' => -6*3600, 'cdt' => -5*3600, 'mst' => -7*3600, 'mdt' => -6*3600, 'pst' => -8*3600, 'pdt' => -7*3600, 'a' => 1*3600, 'b' => 2*3600, 'c' => 3*3600, 'd' => 4*3600, 'e' => 5*3600, 'f' => 6*3600, 'g' => 7*3600, 'h' => 8*3600, 'i' => 9*3600, 'k' => 10*3600, 'l' => 11*3600, 'm' => 12*3600, 'n' => -1*3600, 'o' => -2*3600, 'p' => -3*3600, 'q' => -4*3600, 'r' => -5*3600, 's' => -6*3600, 't' => -7*3600, 'u' => -8*3600, 'v' => -9*3600, 'w' =>-10*3600, 'x' =>-11*3600, 'y' =>-12*3600, 'z' => 0*3600, 'utc' => 0*3600, 'wet' => 0*3600, 'bst' => 1*3600, 'wat' => -1*3600, 'at' => -2*3600, 'ast' => -4*3600, 'adt' => -3*3600, 'yst' => -9*3600, 'ydt' => -8*3600, 'hst' =>-10*3600, 'hdt' => -9*3600, 'cat' =>-10*3600, 'ahst'=>-10*3600, 'nt' =>-11*3600, 'idlw'=>-12*3600, 'cet' => 1*3600, 'met' => 1*3600, 'mewt'=> 1*3600, 'mest'=> 2*3600, 'mesz'=> 2*3600, 'swt' => 1*3600, 'sst' => 2*3600, 'fwt' => 1*3600, 'fst' => 2*3600, 'eet' => 2*3600, 'bt' => 3*3600, 'zp4' => 4*3600, 'zp5' => 5*3600, 'zp6' => 6*3600, 'wast'=> 7*3600, 'wadt'=> 8*3600, 'cct' => 8*3600, 'jst' => 9*3600, 'east'=> 10*3600, 'eadt'=> 11*3600, 'gst' => 10*3600, 'nzt' => 12*3600, 'nzst'=> 12*3600, 'nzdt'=> 13*3600, 'idle'=> 12*3600
PARSE_MONTHPAT | = | ABBR_MONTHS.keys.join('|')
PARSE_DAYPAT | = | ABBR_DAYS. keys.join('|')

### External Aliases

gregorian_leap? | -> | leap?
new | -> | new0
valid_civil? | -> | valid_date?
civil | -> | new

### Public Class methods

_load(str)

Load from Marshall format.

[Source]

    # File date.rb, line 1032
      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
        new0(ajd, of, sg)
      end

_parse(str, comp=false)

[Source]

    # File date/format.rb, line 250
      def self._parse(str, comp=false)
        str = str.dup

        str.gsub!(/[^-+,.\/:0-9a-z]+/ino, ' ')

        # day
        if str.sub!(/(#{PARSE_DAYPAT})\S*/ino, ' ')
          wday = ABBR_DAYS[$1.downcase]
        end

        # time
        if str.sub!(
                    /(\d+):(\d+)
                     (?:
                       :(\d+)(?:[,.](\d*))?
                     )?
                     (?:
                       \s*
                       ([ap])(?:m\b|\.m\.)
                     )?
                     (?:
                       \s*
                       (
                         [a-z]+(?:\s+dst)?\b
                       |
                         [-+]\d+(?::?\d+)
                       )
                     )?
                    /inox,
                    ' ')
          hour = $1.to_i
          min = $2.to_i
          sec = $3.to_i if $3
          if $4
            sec_fraction = $4.to_i.to_r / (10**$4.size)
          end

          if $5
            hour %= 12
            if $5.downcase == 'p'
              hour += 12
            end
          end

          if $6
            zone = $6
          end
        end

        # eu
        if str.sub!(
                    /(\d+)\S*
                     \s+
                     (#{PARSE_MONTHPAT})\S*
                     (?:
                       \s+
                       (-?\d+)
                     )?
                    /inox,
                    ' ')
          mday = $1.to_i
          mon = ABBR_MONTHS[$2.downcase]

          if $3
            year = $3.to_i
            if $3.size > 2
              comp = false
            end
          end

        # us
        elsif str.sub!(
                       /(#{PARSE_MONTHPAT})\S*
                        \s+
                        (\d+)\S*
                        (?:
                          \s+
                          (-?\d+)
                        )?
                       /inox,
                       ' ')
          mon = ABBR_MONTHS[$1.downcase]
          mday = $2.to_i

          if $3
            year = $3.to_i
            if $3.size > 2
              comp = false
            end
          end

        # iso
        elsif str.sub!(/([-+]?\d+)-(\d+)-(-?\d+)/no, ' ')
          year = $1.to_i
          mon = $2.to_i
          mday = $3.to_i

          if $1.size > 2
            comp = false
          elsif $3.size > 2
            comp = false
            mday, mon, year = year, mon, mday
          end

        # jis
        elsif str.sub!(/([MTSH])(\d+)\.(\d+)\.(\d+)/ino, ' ')
          e = { 'm'=>1867,
                't'=>1911,
                's'=>1925,
                'h'=>1988
              }[$1.downcase]
          year = $2.to_i + e
          mon = $3.to_i
          mday = $4.to_i

        # vms
        elsif str.sub!(/(-?\d+)-(#{PARSE_MONTHPAT})[^-]*-(-?\d+)/ino, ' ')
          mday = $1.to_i
          mon = ABBR_MONTHS[$2.downcase]
          year = $3.to_i

          if $1.size > 2
            comp = false
            year, mon, mday = mday, mon, year
          elsif $3.size > 2
            comp = false
          end

        # sla
        elsif str.sub!(%r|(-?\d+)/(\d+)(?:/(-?\d+))?|no, ' ')
          mon = $1.to_i
          mday = $2.to_i

          if $3
            year = $3.to_i
            if $3.size > 2
              comp = false
            end
          end

          if $3 && $1.size > 2
            comp = false
            year, mon, mday = mon, mday, year
          end

        # ddd
        elsif str.sub!(
                       /([-+]?)(\d{4,14})
                        (?:
                          \s*
                          T?
                          \s*
                          (\d{2,6})(?:[,.](\d*))?
                        )?
                        (?:
                          \s*
                          (
                            Z
                          |
                            [-+]\d{2,4}
                          )
                          \b
                        )?
                       /inox,
                       ' ')
          case $2.size
          when 4
            mon  = $2[ 0, 2].to_i
            mday = $2[ 2, 2].to_i
          when 6
            year = ($1 + $2[ 0, 2]).to_i
            mon  = $2[ 2, 2].to_i
            mday = $2[ 4, 2].to_i
          when 8, 10, 12, 14
            year = ($1 + $2[ 0, 4]).to_i
            mon  = $2[ 4, 2].to_i
            mday = $2[ 6, 2].to_i
            hour = $2[ 8, 2].to_i if $2.size >= 10
            min  = $2[10, 2].to_i if $2.size >= 12
            sec  = $2[12, 2].to_i if $2.size >= 14
            comp = false
          end
          if $3
            case $3.size
            when 2, 4, 6
              hour = $3[ 0, 2].to_i
              min  = $3[ 2, 2].to_i if $3.size >= 4
              sec  = $3[ 4, 2].to_i if $3.size >= 6
            end
          end
          if $4
            sec_fraction = $4.to_i.to_r / (10**$4.size)
          end
          if $5
            zone = $5
          end
        end

        if str.sub!(/\b(bc\b|bce\b|b\.c\.|b\.c\.e\.)/ino, ' ')
          if year
            year = -year + 1
          end
        end

        if comp and year
          if year >= 0 and year <= 99
            if year >= 69
              year += 1900
            else
              year += 2000
            end
          end
        end

        elem = {}
        elem[:year] = year if year
        elem[:mon] = mon if mon
        elem[:mday] = mday if mday
        elem[:hour] = hour if hour
        elem[:min] = min if min
        elem[:sec] = sec if sec
        elem[:sec_fraction] = sec_fraction if sec_fraction
        elem[:zone] = zone if zone
        offset = zone_to_diff(zone) if zone
        elem[:offset] = offset if offset
        elem[:wday] = wday if wday
        elem
      end

_strptime(str, fmt='%F')

[Source]

    # File date/format.rb, line 242
      def self._strptime(str, fmt='%F')
        elem = {}
        elem if __strptime(str.dup, fmt, elem)
      end

ajd_to_amjd(ajd)

Convert an Astronomical Julian Day Number to an Astronomical Modified Julian Day Number.

[Source]

    # File date.rb, line 448
      def self.ajd_to_amjd(ajd) ajd - 4800001.to_r/2 end

ajd_to_jd(ajd, of=0)

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.

[Source]

    # File date.rb, line 414
      def self.ajd_to_jd(ajd, of=0) clfloor(ajd + of + 1.to_r/2) end

amjd_to_ajd(amjd)

Convert an Astronomical Modified Julian Day Number to an Astronomical Julian Day Number.

[Source]

    # File date.rb, line 444
      def self.amjd_to_ajd(amjd) amjd + 4800001.to_r/2 end

civil(y=-4712, m=1, d=1, sg=ITALY)

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.

[Source]

    # File date.rb, line 590
      def self.civil(y=-4712, m=1, d=1, sg=ITALY)
        unless jd = valid_civil?(y, m, d, sg)
          raise ArgumentError, 'invalid date'
        end
        new0(jd_to_ajd(jd, 0, 0), 0, sg)
      end

civil_to_jd(y, m, d, sg=GREGORIAN)

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.

[Source]

    # File date.rb, line 295
      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 os?(jd, sg)
          jd -= b
        end
        jd
      end

commercial(y=1582, w=41, d=5, sg=ITALY)

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.

[Source]

    # File date.rb, line 640
      def self.commercial(y=1582, w=41, d=5, sg=ITALY)
        unless jd = valid_commercial?(y, w, d, sg)
          raise ArgumentError, 'invalid date'
        end
        new0(jd_to_ajd(jd, 0, 0), 0, sg)
      end

commercial_to_jd(y, w, d, ns=GREGORIAN)

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.

[Source]

    # File date.rb, line 384
      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

day_fraction_to_time(fr)

Convert a fractional day `fr` to [hours, minutes, seconds, fraction_of_a_second]

[Source]

    # File date.rb, line 429
      def self.day_fraction_to_time(fr)
        h,   fr = clfloor(fr, 1.to_r/24)
        min, fr = clfloor(fr, 1.to_r/1440)
        s,   fr = clfloor(fr, 1.to_r/86400)
        return h, min, s, fr
      end

gregorian_leap?(y)

Is a year a leap year in the Gregorian calendar?

All years divisible by 4 are leap years in the Gregorian calendar, except for years divisible by 100 and not by 400.

[Source]

    # File date.rb, line 480
      def self.gregorian_leap? (y) y % 4 == 0 and y % 100 != 0 or y % 400 == 0 end

jd(jd=0, sg=ITALY)

Create a new Date object from a Julian Day Number.

`jd` is the Julian Day Number; if not specified, it defaults to 0. `sg` specifies the Day of Calendar Reform.

[Source]

    # File date.rb, line 496
      def self.jd(jd=0, sg=ITALY)
        jd = valid_jd?(jd, sg)
        new0(jd_to_ajd(jd, 0, 0), 0, sg)
      end

jd_to_ajd(jd, fr, of=0)

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.

[Source]

    # File date.rb, line 425
      def self.jd_to_ajd(jd, fr, of=0) jd + fr - of - 1.to_r/2 end

jd_to_civil(jd, sg=GREGORIAN)

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.

[Source]

    # File date.rb, line 317
      def self.jd_to_civil(jd, sg=GREGORIAN)
        if os?(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

jd_to_commercial(jd, sg=GREGORIAN)

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]

[Source]

    # File date.rb, line 369
      def self.jd_to_commercial(jd, sg=GREGORIAN)
        ns = ns?(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
        d = (jd + 1) % 7
        if d.zero? then d = 7 end
        return y, w, d
      end

jd_to_ld(jd)

Convert a Julian Day Number to the number of days since the adoption of the Gregorian Calendar (in Italy).

[Source]

    # File date.rb, line 464
      def self.jd_to_ld(jd) jd - 2299160 end

jd_to_mjd(jd)

Convert a Julian Day Number to a Modified Julian Day Number.

[Source]

    # File date.rb, line 456
      def self.jd_to_mjd(jd) jd - 2400001 end

jd_to_ordinal(jd, sg=GREGORIAN)

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]

[Source]

    # File date.rb, line 356
      def self.jd_to_ordinal(jd, sg=GREGORIAN)
        y = jd_to_civil(jd, sg)[0]
        doy = jd - civil_to_jd(y - 1, 12, 31, ns?(jd, sg))
        return y, doy
      end

jd_to_wday(jd)

Convert a Julian Day Number to the day of the week.

Sunday is day-of-week 0; Saturday is day-of-week 6.

[Source]

    # File date.rb, line 469
      def self.jd_to_wday(jd) (jd + 1) % 7 end

julian_leap?(y)

Is a year a leap year in the Julian calendar?

All years divisible by 4 are leap years in the Julian calendar.

[Source]

    # File date.rb, line 474
      def self.julian_leap? (y) y % 4 == 0 end

ld_to_jd(ld)

Convert a count of the number of days since the adoption of the Gregorian Calendar (in Italy) to a Julian Day Number.

[Source]

    # File date.rb, line 460
      def self.ld_to_jd(ld) ld + 2299160 end

mjd_to_jd(mjd)

Convert a Modified Julian Day Number to a Julian Day Number.

[Source]

    # File date.rb, line 452
      def self.mjd_to_jd(mjd) mjd + 2400001 end

new(ajd=0, of=0, sg=ITALY)

NOTE this is the documentation for the method new0(). 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.

Create a new Date object.

`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.

[Source]

    # File date.rb, line 751
      def initialize(ajd=0, of=0, sg=ITALY) @ajd, @of, @sg = ajd, of, sg end

ns?(jd, sg)

Does a given Julian Day Number fall inside the new-style (Gregorian) calendar?

The reverse of self.os? See the documentation for that method for more details.

[Source]

    # File date.rb, line 288
      def self.ns? (jd, sg) not os?(jd, sg) end

ordinal(y=-4712, d=1, sg=ITALY)

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.

[Source]

    # File date.rb, line 538
      def self.ordinal(y=-4712, d=1, sg=ITALY)
        unless jd = valid_ordinal?(y, d, sg)
          raise ArgumentError, 'invalid date'
        end
        new0(jd_to_ajd(jd, 0, 0), 0, sg)
      end

ordinal_to_jd(y, d, sg=GREGORIAN)

Convert an Ordinal Date to a Julian Day Number.

`y` and `d` are the year and day-of-year to convert. `sg` specifies the Day of Calendar Reform.

Returns the corresponding Julian Day Number.

[Source]

    # File date.rb, line 345
      def self.ordinal_to_jd(y, d, sg=GREGORIAN)
        civil_to_jd(y, 1, d, sg)
      end

os?(jd, sg)

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.

[Source]

    # File date.rb, line 276
      def self.os? (jd, sg)
        case sg
        when Numeric; jd < sg
        else;         not sg
        end
      end

parse(str='-4712-01-01', comp=false, sg=ITALY)

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.

[Source]

    # File date.rb, line 694
      def self.parse(str='-4712-01-01', comp=false, sg=ITALY)
        elem = _parse(str, comp)
        new_with_hash(elem, sg)
      end

strptime(str='-4712-01-01', fmt='%F', sg=ITALY)

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.

[Source]

    # File date.rb, line 674
      def self.strptime(str='-4712-01-01', fmt='%F', sg=ITALY)
        elem = _strptime(str, fmt)
        new_with_hash(elem, sg)
      end

time_to_day_fraction(h, min, s)

Convert an `h` hour, `min` minutes, `s` seconds period to a fractional day.

[Source]

    # File date.rb, line 438
      def self.time_to_day_fraction(h, min, s)
        h.to_r/24 + min.to_r/1440 + s.to_r/86400
      end

today(sg=ITALY)

Create a new Date object representing today.

`sg` specifies the Day of Calendar Reform.

[Source]

    # File date.rb, line 702
      def self.today(sg=ITALY)
        jd = civil_to_jd(*(Time.now.to_a[3..5].reverse << sg))
        new0(jd_to_ajd(jd, 0, 0), 0, sg)
      end

valid_civil?(y, m, d, sg=ITALY)

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.

[Source]

    # File date.rb, line 557
      def self.valid_civil? (y, m, d, sg=ITALY)
        if m < 0
          m += 13
        end
        if d < 0
          ny, nm = clfloor(y * 12 + m, 12)
          nm,    = clfloor(nm + 1, 1)
          jd = civil_to_jd(ny, nm, d + 1, sg)
          ns = ns?(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

valid_commercial?(y, w, d, sg=ITALY)

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.

[Source]

    # File date.rb, line 613
      def self.valid_commercial? (y, w, d, sg=ITALY)
        if d < 0
          d += 8
        end
        if w < 0
          w = jd_to_commercial(commercial_to_jd(y + 1, 1, 1) + w * 7)[1]
        end
        jd = commercial_to_jd(y, w, d)
        return unless ns?(jd, sg)
        return unless [y, w, d] == jd_to_commercial(jd)
        jd
      end

valid_jd?(jd, sg=ITALY)

Is `jd` a valid Julian Day Number?

If it is, returns it. In fact, any value is treated as a valid Julian Day Number.

[Source]

    # File date.rb, line 489
      def self.valid_jd? (jd, sg=ITALY) jd end

valid_ordinal?(y, d, sg=ITALY)

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.

[Source]

    # File date.rb, line 514
      def self.valid_ordinal? (y, d, sg=ITALY)
        if d < 0
          ny, = clfloor(y + 1, 1)
          jd = ordinal_to_jd(ny, d + 1, sg)
          ns = ns?(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

zone_to_diff(str)

[Source]

    # File date/format.rb, line 479
      def self.zone_to_diff(str)
        abb, dst = str.downcase.split(/\s+/o, 2)
        if ZONES.include?(abb)
          offset  = ZONES[abb]
          offset += 3600 if dst
        elsif /\A([-+])(\d{2}):?(\d{2})?\Z/no =~ str
          offset = $2.to_i * 3600 + $3.to_i * 60
          offset *= -1 if $1 == '-'
        end
        offset
      end

### Public Instance methods

+(n)

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.

[Source]

    # File date.rb, line 901
      def + (n)
        case n
        when Numeric; return self.class.new0(@ajd + n, @of, @sg)
        end
        raise TypeError, 'expected numeric'
      end

-(x)

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.

[Source]

    # File date.rb, line 916
      def - (x)
        case x
        when Numeric; return self.class.new0(@ajd - x, @of, @sg)
        when Date;    return @ajd - x.ajd
        end
        raise TypeError, 'expected numeric or date'
      end

<<(n)

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.

[Source]

    # File date.rb, line 977
      def << (n) self >> -n end

<=>(other)

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.

[Source]

    # File date.rb, line 935
      def <=> (other)
        case other
        when Numeric; return @ajd <=> other
        when Date;    return @ajd <=> other.ajd
        end
        nil
      end

===(other)

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.

[Source]

    # File date.rb, line 949
      def === (other)
        case other
        when Numeric; return jd == other
        when Date;    return jd == other.jd
        end
        false
      end

>>(n)

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.

[Source]

    # File date.rb, line 963
      def >> (n)
        y, m = clfloor(year * 12 + (mon - 1) + n, 12)
        m,   = clfloor(m + 1, 1)
        d = mday
        d -= 1 until jd2 = self.class.valid_civil?(y, m, d, ns?)
        self + (jd2 - jd)
      end

_dump(limit)

Dump to Marshal format.

[Source]

    # File date.rb, line 1027
      def _dump(limit) Marshal.dump([@ajd, @of, @sg], -1) end

ajd()

Get the date as an Astronomical Julian Day Number.

[Source]

    # File date.rb, line 754
      def ajd() @ajd end

amjd()

Get the date as an Astronomical Modified Julian Day Number.

[Source]

    # File date.rb, line 757
      def amjd() self.class.ajd_to_amjd(@ajd) end

asctime()

alias_method :format, :strftime

[Source]

    # File date/format.rb, line 582
      def asctime() strftime('%c') end

ctime()

Alias for asctime

cwday()

Get the commercial day of the week of this date. Monday is commercial day-of-week 1; Sunday is commercial day-of-week 7.

[Source]

    # File date.rb, line 841
      def cwday() commercial[2] end

cweek()

Get the commercial week of the year of this date.

[Source]

    # File date.rb, line 837
      def cweek() commercial[1] end

cwyear()

Get the commercial year of this date. See Commercial Date in the introduction for how this differs from the normal year.

[Source]

    # File date.rb, line 834
      def cwyear() commercial[0] end

day()

Alias for mday

day_fraction()

Get any fractional day part of the date.

[Source]

    # File date.rb, line 765
      def day_fraction() self.class.ajd_to_jd(@ajd, @of)[1] end

downto(min) {|date| ...}

Step backward one day at a time until we reach `min` (inclusive), yielding each date as we go.

[Source]

    # File date.rb, line 1001
      def downto(min, &block) # :yield: date
          step(min, -1, &block)
      end

england()

Create a copy of this Date object that uses the English/Colonial Day of Calendar Reform.

[Source]

    # File date.rb, line 877
      def england() new_start(self.class::ENGLAND) end

eql?(other)

Is this Date equal to `other`?

`other` must both be a Date object, and represent the same date.

[Source]

    # File date.rb, line 1013
      def eql? (other) Date === other and self == other end

gregorian()

Create a copy of this Date object that always uses the Gregorian Calendar.

[Source]

    # File date.rb, line 885
      def gregorian() new_start(self.class::GREGORIAN) end

hash()

Calculate a hash value for this date.

[Source]

    # File date.rb, line 1016
      def hash() @ajd.hash end

inspect()

Return internal object state as a programmer-readable string.

[Source]

    # File date.rb, line 1019
      def inspect() format('#<%s: %s,%s,%s>', self.class, @ajd, @of, @sg) end

italy()

Create a copy of this Date object that uses the Italian/Catholic Day of Calendar Reform.

[Source]

    # File date.rb, line 873
      def italy() new_start(self.class::ITALY) end

jd()

Get the date as a Julian Day Number.

[Source]

    # File date.rb, line 762
      def jd() self.class.ajd_to_jd(@ajd, @of)[0] end

julian()

Create a copy of this Date object that always uses the Julian Calendar.

[Source]

    # File date.rb, line 881
      def julian() new_start(self.class::JULIAN) end

ld()

Get the date as the number of days since the Day of Calendar Reform (in Italy and the Catholic countries).

[Source]

    # File date.rb, line 772
      def ld() self.class.jd_to_ld(jd) end

leap?()

Is this a leap year?

[Source]

    # File date.rb, line 858
      def leap?
        self.class.jd_to_civil(self.class.civil_to_jd(year, 3, 1, ns?) - 1,
                         ns?)[-1] == 29
      end

mday()

Get the day-of-the-month of this date.

[Source]

    # File date.rb, line 802
      def mday() civil[2] end

mjd()

Get the date as a Modified Julian Day Number.

[Source]

    # File date.rb, line 768
      def mjd() self.class.jd_to_mjd(jd) end

mon()

Get the month of this date.

January is month 1.

[Source]

    # File date.rb, line 799
      def mon() civil[1] end

month()

Alias for mon

new_start(sg=self.class::ITALY)

Create a copy of this Date object using a new Day of Calendar Reform.

[Source]

    # File date.rb, line 869
      def new_start(sg=self.class::ITALY) self.class.new0(@ajd, @of, sg) end

next()

Alias for succ

ns?()

Is the current date new-style (Gregorian Calendar)?

[Source]

    # File date.rb, line 853
      def ns? () self.class.ns?(jd, @sg) end

os?()

Is the current date old-style (Julian Calendar)?

[Source]

    # File date.rb, line 850
      def os? () self.class.os?(jd, @sg) end

start()

When is the Day of Calendar Reform for this Date object?

[Source]

    # File date.rb, line 866
      def start() @sg end

step(limit, step) {|date| ...}

Step the current date forward `step` days at a time (or backward, if `step` is negative) until we reach `limit` (inclusive), yielding the resultant date at each step.

[Source]

    # File date.rb, line 983
      def step(limit, step)  # :yield: date
        da = self
        op = [:-,:<=,:>=][step<=>0]
        while da.__send__(op, limit)
          yield da
          da += step
        end
        self
      end

strftime(fmt='%F')

[Source]

    # File date/format.rb, line 491
      def strftime(fmt='%F')
        o = ''
        fmt.scan(/%[EO]?.|./o) do |c|
          cc = c.sub(/^%[EO]?(.)$/o, '%\\1')
          case cc
          when '%A'; o << DAYNAMES[wday]
          when '%a'; o << ABBR_DAYNAMES[wday]
          when '%B'; o << MONTHNAMES[mon]
          when '%b'; o << ABBR_MONTHNAMES[mon]
          when '%C'; o << '%02d' % (year / 100.0).floor             # P2,ID
          when '%c'; o << strftime('%a %b %e %H:%M:%S %Y')
          when '%D'; o << strftime('%m/%d/%y')                      # P2,ID
          when '%d'; o << '%02d' % mday
          when '%e'; o <<  '%2d' % mday
          when '%F'; o << strftime('%Y-%m-%d')                      # ID
          when '%G'; o << '%.4d' %  cwyear                          # ID
          when '%g'; o << '%02d' % (cwyear % 100)                   # ID
          when '%H'; o << '%02d' %   hour
          when '%h'; o << strftime('%b')                            # P2,ID
          when '%I'; o << '%02d' % ((hour % 12).nonzero? or 12)
          when '%j'; o << '%03d' % yday
          when '%k'; o <<  '%2d' %   hour                           # AR,TZ,GL
          when '%l'; o <<  '%2d' % ((hour % 12).nonzero? or 12)     # AR,TZ,GL
          when '%M'; o << '%02d' % min
          when '%m'; o << '%02d' % mon
    ??
          when '%n'; o << "\n"                                      # P2,ID
          when '%P'; o << if hour < 12 then 'am' else 'pm' end      # GL
          when '%p'; o << if hour < 12 then 'AM' else 'PM' end
          when '%R'; o << strftime('%H:%M')                         # ID
          when '%r'; o << strftime('%I:%M:%S %p')                   # P2,ID
          when '%S'; o << '%02d' % sec
          when '%s'                                                 # TZ,GL
            d = ajd - self.class.jd_to_ajd(self.class.civil_to_jd(1970,1,1), 0)
            s = (d * 86400).to_i
            o << '%d' % s
          when '%T'; o << strftime('%H:%M:%S')                      # P2,ID
          when '%t'; o << "\t"                                      # P2,ID
          when '%U', '%W'
            a = self.class.civil_to_jd(year, 1, 1, ns?) + 6
            k = if c == '%U' then 0 else 1 end
            w = (jd - (a - ((a - k) + 1) % 7) + 7) / 7
            o << '%02d' % w
          when '%u'; o <<   '%d' % cwday                            # P2,ID
          when '%V'; o << '%02d' % cweek                            # P2,ID
          when '%v'; o << strftime('%e-%b-%Y')                      # AR,TZ
          when '%w'; o <<   '%d' % wday
          when '%X'; o << strftime('%H:%M:%S')
          when '%x'; o << strftime('%m/%d/%y')
          when '%Y'; o << '%.4d' %  year
          when '%y'; o << '%02d' % (year % 100)
          when '%Z'; o << (if offset.zero? then 'Z' else strftime('%z') end)
          when '%z'                                                 # ID
            o << if offset < 0 then '-' else '+' end
            of = offset.abs
            hh, fr = of.divmod(1.to_r/24)
            mm = fr / (1.to_r/1440)
            o << '%02d' % hh
            o << '%02d' % mm
          when '%%'; o << '%'
          when '%+'; o << strftime('%a %b %e %H:%M:%S %Z %Y')       # TZ
    ??
          when '%1'
            if $VERBOSE
              warn("warning: %1 is deprecated; forget this")
            end
            o <<   '%d' % jd
          when '%2'
            if $VERBOSE
              warn("warning: %2 is deprecated; use '%Y-%j'")
            end
            o << strftime('%Y-%j')
          when '%3'
            if $VERBOSE
              warn("warning: %3 is deprecated; use '%F'")
            end
            o << strftime('%F')
          else;      o << c
          end
        end
        o
      end

succ()

Return a new Date one day after this one.

[Source]

    # File date.rb, line 1006
      def succ() self + 1 end

to_s()

Return the date as a human-readable string.

The format used is YYYY-MM-DD.

[Source]

    # File date.rb, line 1024
      def to_s() strftime end

upto(max) {|date| ...}

Step forward one day at a time until we reach `max` (inclusive), yielding each date as we go.

[Source]

    # File date.rb, line 995
      def upto(max, &block)  # :yield: date
          step(max, +1, &block)
      end

wday()

Get the week day of this date. Sunday is day-of-week 0; Saturday is day-of-week 6.

[Source]

    # File date.rb, line 845
      def wday() self.class.jd_to_wday(jd) end

yday()

Get the day-of-the-year of this date.

January 1 is day-of-the-year 1

[Source]

    # File date.rb, line 794
      def yday() ordinal[1] end

year()

Get the year of this date.

[Source]

    # File date.rb, line 789
      def year() civil[0] end

[Validate]