module Sjekksum::UPC
Module for calculation and validation of UPC
(Universal Product Code) checksums
@see en.wikipedia.org/wiki/Universal_Product_Code#Check_digits Universal Product Code
It's like Luhn
but multiplies by 3 instead of 2. Also it must allow validation of numbers with leading zeros.
Public Instance Methods
Transforms a number by appending the UPC
checksum digit
It will preserve type (Integer/String) and therefore leading zeros.
@example
Sjekksum::UPC.convert("03600024145") #=> "036000241457"
@param number [Integer, String] number without a checksum
@return [Integer, String] final number including the checksum
# File lib/sjekksum/upc.rb, line 62 def convert number raise_on_type_mismatch number typed_conversion number end
Calculates UPC
checksum
@example
Sjekksum::UPC.of("03600024145") #=> 7
@param number [Integer, String] number for which the checksum should be calculated
@return [Integer] calculated checksum
# File lib/sjekksum/upc.rb, line 23 def of number raise_on_type_mismatch number digits = convert_number_to_digits(number) sum = digits.map.with_index do |digit, idx| idx.even? ? (digit * 3) : digit end.reduce(&:+) (10 - sum % 10) % 10 end
UPC
validation of provided number
@example
Sjekksum::UPC.valid?("036000241457") #=> true
@param number [Integer, String] number with included checksum
@return [Boolean]
# File lib/sjekksum/upc.rb, line 44 def valid? number raise_on_type_mismatch number num, check = split_number(number) self.of(num) == check end