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# ecnumber.py - functions for handling European Community Numbers
# Copyright (C) 2023 Daniel Weber
#
# 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
"""EC Number (European Community number).
The EC Number is a unique seven-digit number assigned to chemical substances
for regulatory purposes within the European Union by the European Commission.
More information:
* https://en.wikipedia.org/wiki/European_Community_number
>>> validate('200-001-8')
'200-001-8'
>>> validate('200-001-9')
Traceback (most recent call last):
...
InvalidChecksum: ...
>>> validate('20-0001-8')
Traceback (most recent call last):
...
InvalidFormat: ...
"""
import re
from stdnum.exceptions import *
from stdnum.util import clean
_ec_number_re = re.compile(r'^[0-9]{3}-[0-9]{3}-[0-9]$')
def compact(number):
"""Convert the number to the minimal representation."""
number = clean(number, ' ').strip()
if '-' not in number:
number = '-'.join((number[:3], number[3:6], number[6:]))
return number
def calc_check_digit(number):
"""Calculate the check digit for the number. The passed number should not
have the check digit included."""
number = compact(number).replace('-', '')
return str(
sum((i + 1) * int(n) for i, n in enumerate(number)) % 11)[0]
def validate(number):
"""Check if the number provided is a valid EC Number."""
number = compact(number)
if not len(number) == 9:
raise InvalidLength()
if not _ec_number_re.match(number):
raise InvalidFormat()
if number[-1] != calc_check_digit(number[:-1]):
raise InvalidChecksum()
return number
def is_valid(number):
"""Check if the number provided is a valid EC Number."""
try:
return bool(validate(number))
except ValidationError:
return False
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