Mini Shell

# date.rb: Written by Tadayoshi Funaba 1998-2011

require 'date_core'
require 'date/format'

class Date

  class Infinity < Numeric # :nodoc:

    include Comparable

    def initialize(d=1) @d = d <=> 0 end

    def d() @d end

    protected :d

    def zero? () false end
    def finite? () false end
    def infinite? () d.nonzero? end
    def nan? () d.zero? end

    def abs() self.class.new end

    def -@ () self.class.new(-d) end
    def +@ () self.class.new(+d) end

    def <=> (other)
      case other
      when Infinity; return d <=> other.d
      when Numeric; return d
      else
	begin
	  l, r = other.coerce(self)
	  return l <=> r
	rescue NoMethodError
	end
      end
      nil
    end

    def coerce(other)
      case other
      when Numeric; return -d, d
      else
	super
      end
    end

    def to_f
      return 0 if @d == 0
      if @d > 0
	Float::INFINITY
      else
	-Float::INFINITY
      end
    end

  end

end