1# figi.py - functions for handling FIGI numbers 2# 3# Copyright (C) 2018 Arthur de Jong 4# 5# This library is free software; you can redistribute it and/or 6# modify it under the terms of the GNU Lesser General Public 7# License as published by the Free Software Foundation; either 8# version 2.1 of the License, or (at your option) any later version. 9# 10# This library is distributed in the hope that it will be useful, 11# but WITHOUT ANY WARRANTY; without even the implied warranty of 12# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13# Lesser General Public License for more details. 14# 15# You should have received a copy of the GNU Lesser General Public 16# License along with this library; if not, write to the Free Software 17# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 18# 02110-1301 USA 19 20"""FIGI (Financial Instrument Global Identifier). 21 22The Financial Instrument Global Identifier (FIGI) is a 12-character 23alpha-numerical unique identifier of financial instruments such as common 24stock, options, derivatives, futures, corporate and government bonds, 25municipals, currencies, and mortgage products. 26 27More information: 28 29* https://openfigi.com/ 30* https://en.wikipedia.org/wiki/Financial_Instrument_Global_Identifier 31 32>>> validate('BBG000BLNQ16') 33'BBG000BLNQ16' 34>>> validate('BBG000BLNQ14') 35Traceback (most recent call last): 36 ... 37InvalidChecksum: ... 38""" 39 40from stdnum.exceptions import * 41from stdnum.util import clean, isdigits 42 43 44def compact(number): 45 """Convert the number to the minimal representation. This strips the 46 number of any valid separators and removes surrounding whitespace.""" 47 return clean(number, ' ').strip().upper() 48 49 50def calc_check_digit(number): 51 """Calculate the check digits for the number.""" 52 # we use the full alphabet for the check digit calculation 53 alphabet = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ' 54 # convert to numeric first, then double some, then sum individual digits 55 number = ''.join( 56 str(alphabet.index(n) * (1, 2)[i % 2]) 57 for i, n in enumerate(number[:11])) 58 return str((10 - sum(int(n) for n in number)) % 10) 59 60 61def validate(number): 62 """Check if the number provided is a valid FIGI.""" 63 number = compact(number) 64 if not all(x in '0123456789BCDFGHJKLMNPQRSTVWXYZ' for x in number): 65 raise InvalidFormat() 66 if len(number) != 12: 67 raise InvalidLength() 68 if isdigits(number[0]) or isdigits(number[1]): 69 raise InvalidFormat() 70 if number[:2] in ('BS', 'BM', 'GG', 'GB', 'VG'): 71 raise InvalidComponent() 72 if number[2] != 'G': 73 raise InvalidComponent() 74 if calc_check_digit(number[:-1]) != number[-1]: 75 raise InvalidChecksum() 76 return number 77 78 79def is_valid(number): 80 """Check if the number provided is a valid FIGI.""" 81 try: 82 return bool(validate(number)) 83 except ValidationError: 84 return False 85