Enumerator # pair

pair.shard.rb

module PairEnumerator
 
  def pair
    if block_given?
      if any?
        last_item = self.next
        each do |this_item|
          result = yield(last_item, this_item)
          last_item = this_item
          result
        end
      end
    else
      Enumerator.new do |y|
        pair { |last_item, this_item| y.<<(last_item, this_item) }
      end
    end
  end
 
end
 
class Enumerator
  include PairEnumerator
end