1 files changed, 221 insertions, 0 deletions
diff --git a/lib/date.rb b/lib/date.rb
new file mode 100644
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+++ b/lib/date.rb
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+#
+#               Date.rb - 
+#                       $Release Version: $
+#                       $Revision: 1.2 $
+#                       $Date: 1997/02/14 11:05:29 $
+#                       by Yasuo OHBA(SHL Japan Inc. Technology Dept.)
+#
+# --
+#
+#    September 1752
+#  S  M Tu  W Th  F  S
+#        1  2 14 15 16
+# 17 18 19 20 21 22 23
+# 24 25 26 27 28 29 30
+#       
+
+class Date
+  include Comparable
+  
+  def initialize(y = 1, m = 1, d = 1)
+    if y.kind_of?(String) && y.size == 8
+      @year = y[0,4].to_i
+      @month = y[4,2].to_i
+      @day = y[6,2].to_i
+    else
+      if m.kind_of?(String)
+        ml = {"jan"=>1, "feb"=>2, "mar"=>3, "apr"=>4, "may"=>5, "jun"=>6, "jul"=>7, "aug"=>8, "sep"=>9, "oct"=>10, "nov"=>11, "dec"=>12}
+        m = ml[m.downcase]
+        if m.nil?
+          raise ArgumentError, "Wrong argument. (month)"
+        end
+      end
+      @year = y.to_i
+      @month = m.to_i
+      @day = d.to_i
+    end
+    _check_date
+    return self
+  end
+  
+  def year
+    return @year
+  end
+  
+  def month
+    return @month
+  end
+  
+  def day
+    return @day
+  end
+  
+  def period
+    return Date.period!(@year, @month, @day)
+  end
+  
+  def day_of_week
+    dl = Date.daylist(@year)
+    d = Date.jan1!(@year)
+    for m in 1..(@month - 1)
+      d += dl[m]
+    end
+    d += @day - 1
+    if @year == 1752 && @month == 9 && @day >= 14
+      d -= (14 - 3)
+    end
+    return (d % 7)
+  end
+  
+  Weektag = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"]
+  def name_of_week
+    return Weektag[self.day_of_week]
+  end
+  
+  def +(o)
+    if o.kind_of?(Integer)
+      d = self.period + o
+    elsif o.kind_of?(Date)
+      d = self.period + o.period
+    else
+      raise TypeError, "Illegal type. (Integer or Date)"
+    end
+    return Date.at(d)
+  end
+  
+  def -(o)
+    if o.kind_of?(Integer)
+      d = self.period - o
+    elsif o.kind_of?(Date)
+      d = self.period - o.period
+    else
+      raise TypeError, "Illegal type. (Integer or Date)"
+    end
+    if d <= 0
+      raise ArgumentError, "argument out of range. (self > other)"
+    end
+    return Date.at(d)
+  end
+  
+  def <=>(o)
+    if o.kind_of?(Integer)
+      d = o
+    elsif o.kind_of?(Date)
+      d = o.period
+    else
+      raise TypeError, "Illegal type. (Integer or Date)"
+    end
+    return self.period <=> d
+  end
+
+  def eql?(o)
+    self == o
+  end
+  
+  def hash
+    return @year ^ @month ^ @day
+  end
+  
+  def leapyear?
+    if Date.leapyear(@year) == 1
+      return FALSE
+    else
+      return TRUE
+    end
+  end
+
+  def _check_date
+    m = Date.daylist(@year)
+    if @month < 1 || @month > 12
+      raise ArgumentError, "argument(month) out of range."
+      return nil
+    end
+    if @year == 1752 && @month == 9
+      if @day >= 3 && @day <= 13
+        raise ArgumentError, "argument(1752/09/3-13) out of range."
+        return nil
+      end
+      d = 30
+    else
+      d = m[@month]
+    end
+    if @day < 1 || @day > d
+      raise ArgumentError, "argument(day) out of range."
+      return nil
+    end
+    return self
+  end
+  
+  private :_check_date
+end
+
+def Date.at(d)
+  mm = 1
+  yy = (d / 366.0).to_i
+  if yy != 0
+    dd = d - (Date.period!(yy, 1, 1) - 1)
+  else
+    dd = d
+    yy = 1
+  end
+  dl = Date.daylist(yy)
+  while dd > dl[mm]
+    if dd > dl[0]
+      dd -= dl[0]
+      yy += 1
+      dl = Date.daylist(yy)
+    else
+      dd -= dl[mm]
+      mm += 1
+    end
+  end
+  if yy == 1752 && mm == 9 && dd >= 3 && dd <= 19
+    dd += (14 - 3)              # 1752/09/03-19 -> 1752/09/14-30
+  end
+  
+  return Date.new(yy, mm, dd)
+end
+
+def Date.period!(y, m, d)
+  p = d
+  dl = Date.daylist(y)
+  for mm in 1..(m - 1)
+    p += dl[mm]
+  end
+  p += (y - 1) * 365 + ((y - 1) / 4.0).to_i
+  if (y - 1) > 1752
+    p -= ((y - 1 - 1752) / 100.0).to_i
+    p += ((y - 1 - 1752) / 400.0).to_i
+    p -= (14 - 3)
+  elsif y == 1752 && m == 9 && d >= 14 && d <= 30
+    p -= (14 - 3)
+  end
+  return p
+end
+
+def Date.leapyear(yy)
+  return ((Date.jan1!(yy + 1) + 7 - Date.jan1!(yy)) % 7)
+end
+
+def Date.daylist(yy)
+  case (Date.leapyear(yy))
+  when 1 # non-leapyear
+    return [365, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
+  when 2 # leapyear
+    return [366, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]
+  else   # 1752
+    return [355, 31, 29, 31, 30, 31, 30, 31, 31, 19, 31, 30, 31]
+  end
+end
+
+def Date.jan1!(y)
+  d = 4 + y + (y + 3) / 4
+  if y > 1800
+    d -= (y - 1701) / 100
+    d += (y - 1601) / 400
+  end
+  if y > 1752
+    d += 3
+  end
+  return (d % 7)
+end