187 lines
6.3 KiB
Python
187 lines
6.3 KiB
Python
# isbn.py - functions for handling ISBNs
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#
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# Copyright (C) 2010, 2011, 2012, 2013 Arthur de Jong
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301 USA
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"""ISBN (International Standard Book Number).
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The ISBN is the International Standard Book Number, used to identify
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publications. This module supports both numbers in ISBN-10 (10-digit) and
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ISBN-13 (13-digit) format.
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>>> validate('978-9024538270')
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'9789024538270'
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>>> validate('978-9024538271')
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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>>> compact('1-85798-218-5')
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'1857982185'
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>>> format('9780471117094')
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'978-0-471-11709-4'
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>>> format('1857982185')
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'1-85798-218-5'
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>>> isbn_type('1-85798-218-5')
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'ISBN10'
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>>> isbn_type('978-0-471-11709-4')
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'ISBN13'
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>>> to_isbn13('1-85798-218-5')
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'978-1-85798-218-3'
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>>> to_isbn10('978-1-85798-218-3')
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'1-85798-218-5'
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"""
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from stdnum import ean
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from stdnum.exceptions import *
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from stdnum.util import clean
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def compact(number, convert=False):
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"""Convert the ISBN to the minimal representation. This strips the number
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of any valid ISBN separators and removes surrounding whitespace. If the
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covert parameter is True the number is also converted to ISBN-13
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format."""
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number = clean(number, ' -').strip().upper()
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if len(number) == 9:
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number = '0' + number
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if convert:
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return to_isbn13(number)
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return number
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def _calc_isbn10_check_digit(number):
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"""Calculate the ISBN check digit for 10-digit numbers. The number passed
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should not have the check bit included."""
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check = sum((i + 1) * int(n)
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for i, n in enumerate(number)) % 11
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return 'X' if check == 10 else str(check)
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def validate(number, convert=False):
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"""Checks to see if the number provided is a valid ISBN (either a legacy
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10-digit one or a 13-digit one). This checks the length and the check
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bit but does not check if the group and publisher are valid (use split()
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for that)."""
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number = compact(number, convert=False)
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if not number[:-1].isdigit():
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raise InvalidFormat()
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if len(number) == 10:
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if _calc_isbn10_check_digit(number[:-1]) != number[-1]:
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raise InvalidChecksum()
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elif len(number) == 13:
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ean.validate(number)
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else:
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raise InvalidLength()
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if convert:
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number = to_isbn13(number)
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return number
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def isbn_type(number):
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"""Check the passed number and returns 'ISBN13', 'ISBN10' or None (for
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invalid) for checking the type of number passed."""
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try:
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number = validate(number, convert=False)
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except ValidationError:
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return None
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if len(number) == 10:
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return 'ISBN10'
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elif len(number) == 13:
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return 'ISBN13'
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def is_valid(number):
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"""Checks to see if the number provided is a valid ISBN (either a legacy
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10-digit one or a 13-digit one). This checks the length and the check
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bit but does not check if the group and publisher are valid (use split()
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for that)."""
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try:
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return bool(validate(number))
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except ValidationError:
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return False
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def to_isbn13(number):
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"""Convert the number to ISBN-13 format."""
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number = number.strip()
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min_number = compact(number, convert=False)
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if len(min_number) == 13:
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return number # nothing to do, already ISBN-13
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# put new check digit in place
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number = number[:-1] + ean.calc_check_digit('978' + min_number[:-1])
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# add prefix
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if ' ' in number:
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return '978 ' + number
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elif '-' in number:
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return '978-' + number
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else:
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return '978' + number
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def to_isbn10(number):
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"""Convert the number to ISBN-10 format."""
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number = number.strip()
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min_number = compact(number, convert=False)
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if len(min_number) == 10:
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return number # nothing to do, already ISBN-13
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elif isbn_type(min_number) != 'ISBN13':
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raise InvalidFormat('Not a valid ISBN13.')
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elif not number.startswith('978'):
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raise InvalidFormat('Does not use 978 Bookland prefix.')
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# strip EAN prefix
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number = number[3:-1].strip().strip('-')
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digit = _calc_isbn10_check_digit(min_number[3:-1])
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# append the new check digit
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if ' ' in number:
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return number + ' ' + digit
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elif '-' in number:
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return number + '-' + digit
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else:
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return number + digit
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def split(number, convert=False):
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"""Split the specified ISBN into an EAN.UCC prefix, a group prefix, a
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registrant, an item number and a check-digit. If the number is in ISBN-10
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format the returned EAN.UCC prefix is '978'. If the covert parameter is
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True the number is converted to ISBN-13 format first."""
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from stdnum import numdb
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# clean up number
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number = compact(number, convert)
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# get Bookland prefix if any
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delprefix = False
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if len(number) == 10:
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number = '978' + number
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delprefix = True
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# split the number
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result = numdb.get('isbn').split(number[:-1])
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itemnr = result.pop() if result else ''
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prefix = result.pop(0) if result else ''
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group = result.pop(0) if result else ''
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publisher = result.pop(0) if result else ''
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# return results
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return ('' if delprefix else prefix, group, publisher, itemnr, number[-1])
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def format(number, separator='-', convert=False):
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"""Reformat the passed number to the standard format with the EAN.UCC
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prefix (if any), the group prefix, the registrant, the item number and
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the check-digit separated (if possible) by the specified separator.
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Passing an empty separator should equal compact() though this is less
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efficient. If the covert parameter is True the number is converted to
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ISBN-13 format first."""
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return separator.join(x for x in split(number, convert) if x)
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