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