1 files changed, 267 insertions, 0 deletions
diff --git a/lib/date2.rb b/lib/date2.rb
new file mode 100644
index 0000000000..58bfbe5a23
--- /dev/null
+++ b/lib/date2.rb
@@ -0,0 +1,267 @@
+# date2.rb: Written by Tadayoshi Funaba 1998, 1999
+# $Id: date2.rb,v 1.13 1999/08/11 01:10:02 tadf Exp $
+
+class Date
+
+  include Comparable
+
+  MONTHNAMES = [ nil, 'January', 'February', 'March',
+    'April', 'May', 'June', 'July', 'August',
+    'September', 'October', 'November', 'December' ]
+
+  DAYNAMES = [ 'Sunday', 'Monday', 'Tuesday',
+    'Wednesday', 'Thursday', 'Friday', 'Saturday' ]
+
+  ITALY   = 2299161 # Oct  15, 1582
+  ENGLAND = 2361222 # Sept 14, 1752
+
+  class << self
+
+    def os? (jd, sg)
+      case sg
+      when Numeric; jd < sg
+      else;         not sg
+      end
+    end
+
+    def ns? (jd, sg) not os?(jd, sg) end
+
+    def civil_to_jd(y, m, d, sg=true)
+      if m <= 2
+	y -= 1
+	m += 12
+      end
+      a = (y / 100).to_i
+      b = 2 - a + (a / 4).to_i
+      jd = (365.25 * (y + 4716)).to_i +
+	(30.6001 * (m + 1)).to_i +
+	d + b - 1524
+      if os?(jd, sg)
+	jd -= b
+      end
+      jd
+    end
+
+    def jd_to_civil(jd, sg=true)
+      if os?(jd, sg)
+	a = jd
+      else
+	x = ((jd - 1867216.25) / 36524.25).to_i
+	a = jd + 1 + x - (x / 4).to_i
+      end
+      b = a + 1524
+      c = ((b - 122.1) / 365.25).to_i
+      d = (365.25 * c).to_i
+      e = ((b - d) / 30.6001).to_i
+      dom = b - d - (30.6001 * e).to_i
+      if e <= 13
+	m = e - 1
+	y = c - 4716
+      else
+	m = e - 13
+	y = c - 4715
+      end
+      return y, m, dom
+    end
+
+    def ordinal_to_jd(y, d, sg=true)
+      civil_to_jd(y, 1, d, sg)
+    end
+
+    def jd_to_ordinal(jd, sg=true)
+      y = jd_to_civil(jd, sg)[0]
+      pl = civil_to_jd(y - 1, 12, 31, ns?(jd, sg))
+      doy = jd - pl
+      return y, doy
+    end
+
+    def mjd_to_jd(mjd) mjd + 2400000.5 end
+    def jd_to_mjd(jd) jd - 2400000.5 end
+    def tjd_to_jd(tjd) tjd + 2440000.5 end
+    def jd_to_tjd(jd) jd - 2440000.5 end
+
+    def julian_leap? (y) y % 4 == 0 end
+    def gregorian_leap? (y) y % 4 == 0 and y % 100 != 0 or y % 400 == 0 end
+
+    alias_method :leap?, :gregorian_leap?
+
+    def exist3? (y, m, d, sg=ITALY)
+      if m < 0
+	m += 13
+      end
+      if d < 0
+	ljd = nil
+	31.downto 1 do |ld|
+	  break if ljd = exist3?(y, m, ld, sg)
+	end
+	x  = y * 12 + m
+	ny = x / 12
+	nm = x % 12 + 1
+	d = jd_to_civil(civil_to_jd(ny, nm, 1, ns?(ljd, sg)) + d,
+			ns?(ljd, sg))[-1]
+      end
+      jd = civil_to_jd(y, m, d, sg)
+      if [y, m, d] == jd_to_civil(jd, sg)
+	jd
+      end
+    end
+
+    alias_method :exist?, :exist3?
+
+    def new3(y=-4712, m=1, d=1, sg=ITALY)
+      unless jd = exist3?(y, m, d, sg)
+	fail ArgumentError, 'invalid date'
+      end
+      new(jd, sg)
+    end
+
+    def exist2? (y, d, sg=ITALY)
+      if d < 0
+	ljd = nil
+	366.downto 1 do |ld|
+	  break if ljd = exist2?(y, ld, sg)
+	end
+	ny = y + 1
+	d = jd_to_ordinal(ordinal_to_jd(ny, 1, ns?(ljd, sg)) + d,
+			  ns?(ljd, sg))[-1]
+      end
+      jd = ordinal_to_jd(y, d, sg)
+      if [y, d] == jd_to_ordinal(jd, sg)
+	jd
+      end
+    end
+
+    def new2(y=-4712, d=1, sg=ITALY)
+      unless jd = exist2?(y, d, sg)
+	fail ArgumentError, 'invalid date'
+      end
+      new(jd, sg)
+    end
+
+    def today(sg=ITALY)
+      new(civil_to_jd(*(Time.now.to_a[3..5].reverse << sg)), sg)
+    end
+
+  end
+
+  def initialize(jd=0, sg=ITALY) @jd, @sg = jd, sg end
+
+  def jd() @jd end
+
+  def mjd
+    def self.mjd() @mjd end
+    @mjd = Date.jd_to_mjd(@jd)
+  end
+
+  def tjd
+    def self.tjd() @tjd end
+    @tjd = Date.jd_to_tjd(@jd)
+  end
+
+  def civil
+    def self.year() @year end
+    def self.mon() @mon end
+    def self.month() @mon end
+    def self.mday() @mday end
+    def self.day() @mday end
+    @year, @mon, @mday = Date.jd_to_civil(@jd, @sg)
+  end
+
+  private :civil
+
+  def year
+    civil
+    @year
+  end
+
+  def yday
+    def self.yday() @yday end
+    @yday = Date.jd_to_ordinal(@jd, @sg)[-1]
+    @yday
+  end
+
+  def mon
+    civil
+    @mon
+  end
+
+  alias_method :month, :mon
+
+  def mday
+    civil
+    @mday
+  end
+
+  alias_method :day, :mday
+
+  def wday
+    def self.wday() @wday end
+    @wday = (@jd + 1) % 7
+  end
+
+  def os? () Date.os?(@jd, @sg) end
+  def ns? () Date.ns?(@jd, @sg) end
+
+  def leap?
+    def self.leap?() @leap_p end
+    @leap_p = Date.jd_to_civil(Date.civil_to_jd(year, 3, 1, ns?) - 1,
+			       ns?)[-1] == 29
+  end
+
+  def + (other)
+    case other
+    when Numeric; return Date.new(@jd + other, @sg)
+    end
+    fail TypeError, 'expected numeric'
+  end
+
+  def - (other)
+    case other
+    when Numeric; return Date.new(@jd - other, @sg)
+    when Date;    return @jd - other.jd
+    end
+    fail TypeError, 'expected numeric or date'
+  end
+
+  def <=> (other)
+    case other
+    when Numeric; return @jd <=> other
+    when Date;    return @jd <=> other.jd
+    end
+    fail TypeError, 'expected numeric or date'
+  end
+
+  def downto(min)
+    @jd.downto(min.jd) do |jd|
+      yield Date.new(jd, @sg)
+    end
+    self
+  end
+
+  def upto(max)
+    @jd.upto(max.jd) do |jd|
+      yield Date.new(jd, @sg)
+    end
+    self
+  end
+
+  def step(limit, step)
+    @jd.step(limit.jd, step) do |jd|
+      yield Date.new(jd, @sg)
+    end
+    self
+  end
+
+  def succ() self + 1 end
+
+  alias_method :next, :succ
+
+  def eql? (other) self == other end
+  def hash() @jd end
+  def inspect() format('#<Date: %s,%s>', @jd, @sg) end
+  def to_s() format('%.4d-%02d-%02d', year, mon, mday) end
+
+  def _dump(limit) Marshal.dump([@jd, @sg], -1) end
+  def Date._load(str) Date.new(*Marshal.load(str)) end
+
+end