Module: ISBN13

Defined in:
lib/isbn13.rb,
lib/version.rb

Constant Summary collapse

VERSION = 
'1.0'

Class Method Summary collapse

Class Method Details

.format(isbn) ⇒ Object

Raises:



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# File 'lib/isbn13.rb', line 19

def self.format(isbn)
  raise ISBNError.new("#{isbn} is not a proper ISBN13 number") unless valid_form?(isbn)
  load

  breaks = [3]
  found = false
  size = nil
  @ranges.keys.max.to_s.size.downto(3) do |x|
    found = @ranges.has_key?(isbn[0, x].to_i)
    size = x
    break if found
  end
  raise ISBNError.new("group not found") unless found
  breaks << size - breaks.first

  data = @ranges[isbn[0, size].to_i]
  pub_size = nil
  found = false
  data[:min].upto(isbn.size - breaks.last) do |x|
    found = data[:ranges].any? { |range| range.cover?(isbn[size, x].to_i) }
    pub_size = x
    break if found
  end
  raise ISBNError.new("publisher not found") unless found
  breaks << pub_size

  breaks << isbn.size - breaks.reduce(&:+) - 1
  breaks << 1

  result = []
  idx = 0
  breaks.each do |x|
    result << isbn[idx, x]
    idx += x
  end

  result.join('-')
end

.ranges_path ⇒ Object 



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# File 'lib/isbn13.rb', line 58

def self.ranges_path
  File.join(File.dirname(__FILE__), 'ranges.bin')
end

.valid?(isbn) ⇒ Boolean

based on ruby example on en.wikipedia.org/wiki/International_Standard_Book_Number#ISBN-13

Returns:

  • (Boolean) 


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# File 'lib/isbn13.rb', line 8

def self.valid?(isbn)
  return false if isbn.nil?

  isbn = isbn.gsub(/-/, '')
  return false unless valid_form?(isbn)

  sum = 0
  13.times { |i| sum += i.modulo(2)==0 ? isbn[i].to_i : isbn[i].to_i*3 }
  0 == sum.modulo(10)
end