# isan.py - functions for handling International Standard Audiovisual Numbers
# (ISANs)
#
# Copyright (C) 2010, 2011, 2012, 2013 Arthur de Jong
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
"""ISAN (International Standard Audiovisual Number).
The ISAN (International Standard Audiovisual Number) is used to identify
audiovisual works.
The number is hexadecimal and can consists of at least a root identifier,
and an episode or part. After that an optional check digit, optional
version and optionally another check digit can be provided. The check
digits are validated using the ISO 7064 Mod 37, 36 algorithm.
>>> validate('000000018947000000000000')
'000000018947000000000000'
>>> compact('0000-0000-D07A-0090-Q-0000-0000-X')
'00000000D07A009000000000'
>>> validate('0000-0001-8CFA-0000-I-0000-0000-K')
'000000018CFA0000I00000000K'
>>> validate('0000-0001-8CFA-0000-A-0000-0000-K')
Traceback (most recent call last):
...
InvalidChecksum: ...
>>> format('000000018947000000000000')
'0000-0001-8947-0000-8-0000-0000-D'
>>> to_urn('00000000D07A009000000000')
'URN:ISAN:0000-0000-D07A-0090-Q-0000-0000-X'
>>> to_xml('1881-66C7-3420-6541-Y-9F3A-0245-O')
''
"""
from stdnum.exceptions import *
from stdnum.iso7064 import mod_37_36
from stdnum.util import clean
def split(number):
"""Splits the number into a root, an episode or part, a check digit a
version and another check digit. If any of the parts are missing an
empty string is returned."""
number = clean(number, ' -').strip().upper()
if len(number) == 17 or len(number) == 26:
return number[0:12], number[12:16], number[16], number[17:25], number[25:]
elif len(number) > 16:
return number[0:12], number[12:16], '', number[16:24], number[24:]
else:
return number[0:12], number[12:16], number[16:], '', ''
def compact(number, strip_check_digits=True):
"""Convert the ISAN to the minimal representation. This strips the number
of any valid separators and removes surrounding whitespace. The check
digits are removed by default."""
number = list(split(number))
number[2] = number[4] = ''
return ''.join(number)
def validate(number, strip_check_digits=False, add_check_digits=False):
"""Checks to see if the number provided is a valid ISAN. If check digits
are present in the number they are validated. If strip_check_digits is
True any existing check digits will be removed (after checking). If
add_check_digits is True the check digit will be added if they are not
present yet."""
(root, episode, check1, version, check2) = split(number)
# check digits used
for x in root + episode + version:
if x not in '0123456789ABCDEF':
raise InvalidFormat()
# check length of all components
if len(root) != 12 or len(episode) != 4 or len(check1) not in (0, 1) or \
len(version) not in (0, 8) or len(check1) not in (0, 1):
raise InvalidLength()
# check check digits
if check1:
mod_37_36.validate(root + episode + check1)
if check2:
mod_37_36.validate(root + episode + version + check2)
# remove or add check digits
if strip_check_digits:
check1 = check2 = ''
if add_check_digits and not check1:
check1 = mod_37_36.calc_check_digit(root + episode)
if add_check_digits and not check2 and version:
check2 = mod_37_36.calc_check_digit(root + episode + version)
return root + episode + check1 + version + check2
def is_valid(number):
"""Checks to see if the number provided is a valid ISAN. If check digits
are present in the number they are validated."""
try:
return bool(validate(number))
except ValidationError:
return False
def format(number, separator='-', strip_check_digits=False, add_check_digits=True):
"""Reformat the passed number to the standard format. If
add_check_digits is True the check digit will be added if they are not
present yet. If both strip_check_digits and add_check_digits are True the
check digits will be recalculated."""
(root, episode, check1, version, check2) = split(number)
if strip_check_digits:
check1 = check2 = ''
if add_check_digits and not check1:
check1 = mod_37_36.calc_check_digit(root + episode)
if add_check_digits and not check2 and version:
check2 = mod_37_36.calc_check_digit(root + episode + version)
number = [root[i:i + 4] for i in range(0, 12, 4)] + [episode]
if check1:
number.append(check1)
if version:
number.extend((version[0:4], version[4:]))
if check2:
number.append(check2)
return separator.join(number)
def to_binary(number):
"""Convert the number to it's binary representation (without the check
digits)."""
import sys
number = compact(number, strip_check_digits=True)
if sys.version > '3': # pragma: no cover (Python 2/3 specific code)
return bytes.fromhex(number)
else: # pragma: no cover (Python 2/3 specific code)
return number.decode('hex')
def to_xml(number):
"""Returns the XML form of the ISAN as a string."""
number = format(number, strip_check_digits=True, add_check_digits=False)
return '' % (
number[0:14], number[15:19], number[20:])
def to_urn(number):
"""Returns the URN representation of the ISAN."""
return 'URN:ISAN:' + format(number, add_check_digits=True)