87 lines
2.9 KiB
Python
87 lines
2.9 KiB
Python
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# figi.py - functions for handling FIGI numbers
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#
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# Copyright (C) 2018 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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"""FIGI (Financial Instrument Global Identifier).
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The Financial Instrument Global Identifier (FIGI) is a 12-character
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alpha-numerical unique identifier of financial instruments such as common
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stock, options, derivatives, futures, corporate and government bonds,
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municipals, currencies, and mortgage products.
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More information:
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* https://openfigi.com/
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* https://en.wikipedia.org/wiki/Financial_Instrument_Global_Identifier
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>>> validate('BBG000BLNQ16')
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'BBG000BLNQ16'
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>>> validate('BBG000BLNQ14')
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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"""
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from __future__ import annotations
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from stdnum.exceptions import *
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from stdnum.util import clean, isdigits
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def compact(number: str) -> str:
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"""Convert the number to the minimal representation. This strips the
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number of any valid separators and removes surrounding whitespace."""
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return clean(number, ' ').strip().upper()
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def calc_check_digit(number: str) -> str:
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"""Calculate the check digits for the number."""
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# we use the full alphabet for the check digit calculation
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alphabet = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ'
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# convert to numeric first, then double some, then sum individual digits
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number = ''.join(
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str(alphabet.index(n) * (1, 2)[i % 2])
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for i, n in enumerate(number[:11]))
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return str((10 - sum(int(n) for n in number)) % 10)
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def validate(number: str) -> str:
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"""Check if the number provided is a valid FIGI."""
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number = compact(number)
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if not all(x in '0123456789BCDFGHJKLMNPQRSTVWXYZ' for x in number):
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raise InvalidFormat()
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if len(number) != 12:
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raise InvalidLength()
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if isdigits(number[0]) or isdigits(number[1]):
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raise InvalidFormat()
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if number[:2] in ('BS', 'BM', 'GG', 'GB', 'VG'):
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raise InvalidComponent()
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if number[2] != 'G':
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raise InvalidComponent()
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if calc_check_digit(number[:-1]) != 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 FIGI."""
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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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