def roll_element(element)
      # sample ["1d6", nil, "1", "d6"]
      # sample ["+1d6", "+", "1", "d6"]
      # sample ["+1", "+", "1", nil]
      original, sign, numerator, denominator = element[0], element[1], element[2], element[3]
      sign = "+" unless sign
      error = false

      # Dice cap
      if numerator.to_i > 10000
        numerator = "10000"
        original = sign + numerator + denominator # feign original
        error = true
      end

      if denominator && denominator.delete("d").to_i > 10000
        denominator = "d10000"
        original = sign + numerator + denominator  # feign original
        error = true
      end

      # fix for "d20"
      if (not denominator) and original =~ /^(\+|-)?d(\d+)/
        sign = $1
        numerator = 1
        denominator = $2
      end

      if denominator
        result = []
        numerator.to_i.times do
          result << random(denominator.delete("d").to_i)
        end
      else
        result = [numerator.to_i]
      end

      # flip result unless sign
      if sign == "-"
        result = result.map{ |r| 0 - r}
      end

      # Dice cap
      # invoke "too many dice message" by triggering long line
      if error
        200.times do
          result << 9999
        end
      end

      return result
    end

    def random(value)
      return 0 if value == 0
      return rand(value)+1
    end

  end