module Mod10

Constants

VERSION

Public Instance Methods

generate_check_digit(value) click to toggle source

Returns the Mod10 check digit for the given value, which can be integer or String.

# File lib/mod_10.rb, line 6
def generate_check_digit(value)
  total = 0
  value.to_s.reverse.split(//).map(&:to_i).each_with_index do |el, i|
    el *= 2 if i.even?
    if el > 9
      el = el.to_s.split(//).reduce(0) { |sum, x| sum += x.to_i }
    end
    total += el
  end
  10 - total.to_s[-1].to_i
end

is_mod10?(value) click to toggle source

Checks if a given value has a valid Mod10 check digit.

# File lib/mod_10.rb, line 19
def is_mod10?(value)
  digits = value.to_s.chars.map(&:to_i)
  check_digit = digits.pop

  sum = digits.reverse.each_slice(2).map do |x, y|
    [(x * 2).divmod(10), y || 0]
  end.flatten.inject(:+)

  10 - sum % 10 == check_digit
end