96 lines
3 KiB
Python
96 lines
3 KiB
Python
# itin.py - functions for handling ITINs
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#
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# Copyright (C) 2013 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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"""ITIN (U.S. Individual Taxpayer Identification Number).
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The Individual Taxpayer Identification Number is issued by the United
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States IRS to individuals who are required to have a taxpayer
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identification number but who are not eligible to obtain a Social Security
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Number.
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It is a nine-digit number that begins with the number 9 and the
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fourth and fifth digit are expected to be in a certain range.
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>>> validate('912-90-3456')
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'912903456'
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>>> validate('9129-03456') # dash in the wrong place
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Traceback (most recent call last):
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...
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InvalidFormat: ...
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>>> validate('123-45-6789') # wrong start digit
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Traceback (most recent call last):
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...
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InvalidComponent: ...
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>>> validate('912-93-4567') # wrong group
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Traceback (most recent call last):
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...
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InvalidComponent: ...
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>>> compact('1234-56-789')
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'123456789'
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>>> format('111223333')
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'111-22-3333'
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"""
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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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# regular expression for matching ITINs
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_itin_re = re.compile('^(?P<area>[0-9]{3})-?(?P<group>[0-9]{2})-?[0-9]{4}$')
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# allowed group digits
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_allowed_groups = set((str(x) for x in range(70, 100) if x not in (89, 93)))
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def compact(number):
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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()
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def validate(number):
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"""Checks to see if the number provided is a valid ITIN. This checks
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the length, groups and formatting if it is present."""
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match = _itin_re.search(clean(number, '').strip())
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if not match:
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raise InvalidFormat()
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area = match.group('area')
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group = match.group('group')
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if area[0] != '9' or group not in _allowed_groups:
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raise InvalidComponent()
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return compact(number)
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def is_valid(number):
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"""Checks to see if the number provided is a valid ITIN. This checks
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the length, groups and formatting if it is present."""
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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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def format(number):
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"""Reformat the passed number to the standard format."""
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if len(number) == 9:
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number = number[:3] + '-' + number[3:5] + '-' + number[5:]
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return number
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