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Shared/lib/python3.4/site-packages/stdnum/us/itin.py

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