Sha256: a4649ad4f7afae7c73ba32caee30a819a0c811ce900b42a0cf6aead8bbdc3926
Contents?: true
Size: 722 Bytes
Versions: 16
Compression:
Stored size: 722 Bytes
Contents
require "petrarca/helpers"
module Petrarca
module ISBN10
extend self
def valid?(isbn)
correct_format?(isbn) && isbn[-1] == calc_check_digit(isbn)
end
def correct_format?(isbn)
isbn = isbn.delete("-")
!!(/\A\d{9}[0-9X]\z/ =~ isbn)
end
def calc_check_digit(isbn)
nums = isbn.delete("-").split("")[0, 9].map{|x| x.to_i }
sum = nums.zip((2..10).to_a.reverse).map{|x, y| x * y }.inject(:+)
check_digit = 11 - (sum % 11)
case check_digit
when 10
"X"
when 11
"0"
else
check_digit.to_s
end
end
def hyphenate(isbn)
s = ISBN13.hyphenate("978" + isbn)
s.sub(/^978-/, "")
end
end
end
Version data entries
16 entries across 16 versions & 1 rubygems