Class: RBook::ISBN

Inherits:
Object
  • Object
show all
Defined in:
lib/rbook/isbn.rb

Overview

A collection of useful functions for dealing with ISBNs. Each function can be used directly - examples listed below. To use these examples you will need the following 2 lines at the top of your script:

require 'rubygems'
require 'rbook/isbn'

Class Method Summary collapse

Class Method Details

.add_groups(isbn) ⇒ Object

adds hyphens to a valid isbn in the appropriate spots

ISBN.add_groups("020161622X")
      #=> 0-201-61622-X
ISBN.add_groups("9780201616224")
      #=> 978-0-201-61622-4



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# File 'lib/rbook/isbn.rb', line 16

def self.add_groups(isbn)
  return nil unless isbn.class == String
  if valid_isbn10?(isbn)
    isbn = isbn.gsub("-","")
    isbn = isbn.insert(1, "-")
    isbn = isbn.insert(7, "-")
    isbn = isbn.insert(11, "-")
    return isbn
  elsif valid_isbn13?(isbn)
    isbn = isbn.gsub("-","")
    isbn = isbn.insert(3, "-")
    isbn = isbn.insert(5, "-")
    isbn = isbn.insert(11, "-")
    isbn = isbn.insert(15, "-")
    return isbn
  else
    return isbn
  end
end

.calc_isbn10_check(isbn) ⇒ Object

Attempts to calculate the check digit on a supplied 9 digit string.

If passed nil or a non string, nil is returned.

If the supplied string length isn’t chars 9 long, nil is returned.

If the supplied string is 9 chars long, the check digit is calculated and returned

ISBN.calc_isbn10_check("020161622")
      #=> X
ISBN.calc_isbn10_check("020161622X")
      #=> nil
ISBN.calc_isbn10_check("9780201616224")
      #=> nil
ISBN.calc_isbn10_check("9780201616223")
      #=> nil
ISBN.calc_isbn10_check("not an isbn")
      #=> nil



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# File 'lib/rbook/isbn.rb', line 117

def self.calc_isbn10_check(isbn)
  if isbn.nil? || isbn.class != String || isbn.length != 9
    return nil
  else
    check = isbn[0,1].to_i
    check = check + isbn[1,1].to_i * 2
    check = check + isbn[2,1].to_i * 3
    check = check + isbn[3,1].to_i * 4
    check = check + isbn[4,1].to_i * 5
    check = check + isbn[5,1].to_i * 6
    check = check + isbn[6,1].to_i * 7
    check = check + isbn[7,1].to_i * 8
    check = check + isbn[8,1].to_i * 9
    check = check % 11

    if check == 10
      return "X"
    else
      return check.to_s
    end
  end
end

.calc_isbn13_check(isbn) ⇒ Object

Attempts to calculate the check digit on a supplied 12 digit string.

If passed nil or a non String, nil is returned.

If the supplied string isn’t 12 digits long, nil is returned.

For all other strings the check digit will be returned

ISBN.calc_isbn13_check("978020161622")
      #=> 4
ISBN.calc_isbn13_check("9780201616224")
      #=> nil
ISBN.calc_isbn13_check("020161622X")
      #=> nil
ISBN.calc_isbn13_check("9780201616223")
      #=> nil
ISBN.calc_isbn13_check("not an isbn")
      #=> nil



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# File 'lib/rbook/isbn.rb', line 158

def self.calc_isbn13_check(isbn)
  if isbn.nil? || isbn.class != String || isbn.length != 12
    return nil
  else
    checkdigit = isbn[0,1].to_i * 1
    checkdigit = checkdigit + isbn[1,1].to_i * 3
    checkdigit = checkdigit + isbn[2,1].to_i * 1
    checkdigit = checkdigit + isbn[3,1].to_i * 3
    checkdigit = checkdigit + isbn[4,1].to_i * 1
    checkdigit = checkdigit + isbn[5,1].to_i * 3
    checkdigit = checkdigit + isbn[6,1].to_i * 1
    checkdigit = checkdigit + isbn[7,1].to_i * 3
    checkdigit = checkdigit + isbn[8,1].to_i * 1
    checkdigit = checkdigit + isbn[9,1].to_i * 3
    checkdigit = checkdigit + isbn[10,1].to_i * 1
    checkdigit = checkdigit + isbn[11,1].to_i * 3

    remainder = checkdigit % 10

    if remainder == 0
      checkdigit = 0
    else
      checkdigit = (10 - remainder)
    end

    return checkdigit.to_s

  end
end

.convert_to_isbn10(convert_me) ⇒ Object

Attempts to convert a valid isbn13 into an isbn10.

If supplied string is a valid isbn10, it is returned unchanged.

If if the string is a valid isbn13 and starts with 978, it is converted to an isbn10.

All other strings return nil.

ISBN.convert_to_isbn10("9780201616224")
      #=> 020161622X
ISBN.convert_to_isbn10("020161622X")
      #=> 020161622X
ISBN.convert_to_isbn10("9793472834833")
      #=> nil
ISBN.convert_to_isbn10("not an isbn")
      #=> nil



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# File 'lib/rbook/isbn.rb', line 204

def self.convert_to_isbn10(convert_me)
  return nil unless convert_me.class == String
  convert_me = convert_me.gsub("-","")
  if self.valid_isbn10?(convert_me)
    convert_me
  elsif self.valid_isbn13?(convert_me) && convert_me[0,3] == '978'
    convert_me[3,9] + self.calc_isbn10_check(convert_me[3,9])
  else
    nil
  end
end

.convert_to_isbn13(convert_me) ⇒ Object

Attempts to convert the supplied string into an ISBN13.

If the string is a valid isbn13, it is returned unchanged.

If the string is a valid isbn10, it will be converted to isbn13.

All other strings will return nil.

ISBN.convert_to_isbn13("020161622X")
      #=> 9780201616224
ISBN.convert_to_isbn13("9780201616224")
      #=> 9780201616224
ISBN.convert_to_isbn13("9793472834833")
      #=> nil
ISBN.convert_to_isbn13("not an isbn")
      #=> nil



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# File 'lib/rbook/isbn.rb', line 232

def self.convert_to_isbn13(convert_me)
  return nil unless convert_me.class == String
  convert_me = convert_me.gsub("-","")
  if self.valid_isbn13?(convert_me)
    convert_me
  elsif self.valid_isbn10?(convert_me)
  '978'+convert_me[0,9] + self.calc_isbn13_check('978'+convert_me[0,9])
  else
    nil
  end
end

.valid_isbn10?(isbn) ⇒ Boolean

returns true if the supplied string is a valid isbn10

ISBN.valid_isbn10?("020161622X")
      #=> true
ISBN.valid_isbn10?("9780201616224")
      #=> false
ISBN.valid_isbn10?("9780201616223")
      #=> false
ISBN.valid_isbn10?("not an isbn")
      #=> false

Returns:

  • (Boolean) 


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# File 'lib/rbook/isbn.rb', line 60

def self.valid_isbn10?(isbn)
  return false unless isbn.class == String
  isbn = isbn.gsub("-","")
  if isbn.length != 10
    false
  elsif isbn[/[^\dxX]/]
    false
  else
    checkdigit = self.calc_isbn10_check(isbn.to_s[0,9])
    if checkdigit.eql?("X")
      isbn == isbn[0,9] + "x" || isbn == isbn[0,9] + "X"
    else
      isbn == isbn[0,9] + checkdigit
    end
  end
end

.valid_isbn13?(isbn) ⇒ Boolean

returns true if the supplied string is a valid isbn13

ISBN.valid_isbn13?("020161622X")
      #=> false
ISBN.valid_isbn13?("9780201616224")
      #=> true
ISBN.valid_isbn13?("9780201616223")
      #=> false
ISBN.valid_isbn13?("not an isbn")
      #=> false

Returns:

  • (Boolean) 


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# File 'lib/rbook/isbn.rb', line 87

def self.valid_isbn13?(isbn)
  return false unless isbn.class == String
  isbn = isbn.gsub("-","")
  if isbn.length != 13
    false
  elsif isbn[/[^\dxX]/]
    false
  else
    isbn == isbn[0,12] + self.calc_isbn13_check(isbn[0,12])
  end
end

.valid_isbn?(isbn) ⇒ Boolean

Returns true if the supplied string is a valid isbn10 or isbn13

ISBN.valid_isbn?("020161622X")
      #=> true
ISBN.valid_isbn?("9780201616224")
      #=> true
ISBN.valid_isbn?("9780201616223")
      #=> false
ISBN.valid_isbn?("not an isbn")
      #=> false

Returns:

  • (Boolean) 


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# File 'lib/rbook/isbn.rb', line 46

def self.valid_isbn?(isbn)
  valid_isbn10?(isbn) || valid_isbn13?(isbn)
end