Class: Lisbn

Inherits:
String
  • Object
show all
Extended by:
CacheMethod
Defined in:
lib/lisbn/lisbn.rb,
lib/lisbn/ranges.rb,
lib/lisbn/cache_method.rb

Defined Under Namespace

Modules: CacheMethod, Ranges

Instance Method Summary collapse

Methods included from CacheMethod

cache_method

Instance Method Details

#isbn ⇒ Object

Returns a normalized ISBN form



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# File 'lib/lisbn/lisbn.rb', line 3

def isbn
  upcase.gsub(/[^0-9X]/, '')
end

#isbn10 ⇒ Object

Returns a valid ISBN in ISBN-10 format. Returns nil if the ISBN is invalid or incapable of conversion to ISBN-10.



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# File 'lib/lisbn/lisbn.rb', line 31

def isbn10
  return unless valid?
  return isbn if isbn.length == 10
  return unless isbn[0..2] == "978"

  isbn[3..-2] + isbn_10_checksum
end

#isbn13 ⇒ Object

Returns a valid ISBN in ISBN-13 format. Returns nil if the ISBN is invalid.



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# File 'lib/lisbn/lisbn.rb', line 41

def isbn13
  return unless valid?
  return isbn if isbn.length == 13

  '978' + isbn[0..-2] + isbn_13_checksum
end

#isbn_10_checksum ⇒ Object 



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# File 'lib/lisbn/lisbn.rb', line 86

def isbn_10_checksum
  base = isbn.length == 13 ? isbn[3..-2] : isbn[0..-2]

  products = base.each_char.each_with_index.map do |chr, i|
    chr.to_i * (10 - i)
  end

  remainder = products.inject(0) {|m, v| m + v} % 11
  case remainder
    when 0
      0
    when 1
      'X'
    else
      11 - remainder
  end.to_s
end

#isbn_13_checksum ⇒ Object 



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# File 'lib/lisbn/lisbn.rb', line 104

def isbn_13_checksum
  base = (isbn.length == 13 ? '' : '978') + isbn[0..-2]

  products = base.each_char.each_with_index.map do |chr, i|
    chr.to_i * (i % 2 == 0 ? 1 : 3)
  end

  remainder = products.inject(0) {|m, v| m + v} % 10
  (remainder == 0 ? 0 : 10 - remainder).to_s
end

#isbn_with_dash ⇒ Object 



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

def isbn_with_dash
  if valid_isbn_13? && parts
    parts.join("-")
  elsif isbn.length > 3
    isbn[0..-2] + "-" + isbn[-1]
  else
    isbn
  end
end

#parts ⇒ Object

Returns an Array with the 'parts' of the ISBN-13 in left-to-right order. The parts of an ISBN are as follows:

- GS1 prefix
- Group identifier
- Prefix/publisher code
- Item number
- Check digit

Returns nil if the ISBN is not valid. Returns nil if the group and prefix cannot be identified.



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

def parts
  return unless isbn13

  group = prefix = nil

  RANGES.each_pair do |g, prefixes|
    next unless isbn13.match("^#{g}")
    group = g

    pre_loc = group.length
    prefixes.each do |p|
      number = isbn13.slice(pre_loc, p[:length]).to_i
      next unless p[:range].include?(number)

      prefix = p.merge(:number => number)
      break
    end

    break
  end

  # In the unlikely event we can't categorize it...
  return unless group && prefix

  prefix = sprintf("%0#{prefix[:length]}d", prefix[:number])
  [group[0..2], group[3..-1], prefix, isbn13[(group.length + prefix.length)..-2], isbn13[-1..-1]]
end

#valid? ⇒ Boolean

Returns true if the ISBN is valid, false otherwise.

Returns:

  • (Boolean) 


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

def valid?
  case isbn.length
    when 10
      valid_isbn_10?
    when 13
      valid_isbn_13?
    else
      false
  end
end