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Shared/lib/python3.4/site-packages/stdnum/issn.py

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+# issn.py - functions for handling ISSNs
+#
+# Copyright (C) 2010, 2011, 2012, 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
+
+"""ISSN (International Standard Serial Number).
+
+The ISSN (International Standard Serial Number) is the standard code to
+identify periodical publications. It has a checksum similar to ISBN-10.
+
+>>> validate('0024-9319')
+'00249319'
+>>> validate('0032147X')
+Traceback (most recent call last):
+    ...
+InvalidChecksum: ...
+>>> validate('003214712')
+Traceback (most recent call last):
+    ...
+InvalidLength: ...
+>>> compact('0032-1478')
+'00321478'
+>>> format('00249319')
+'0024-9319'
+>>> to_ean('0264-3596')
+'9770264359008'
+"""
+
+from stdnum import ean
+from stdnum.exceptions import *
+from stdnum.util import clean
+
+
+def compact(number):
+    """Convert the ISSN to the minimal representation. This strips the number
+    of any valid ISSN separators and removes surrounding whitespace."""
+    return clean(number, ' -').strip().upper()
+
+
+def calc_check_digit(number):
+    """Calculate the ISSN check digit for 10-digit numbers. The number passed
+    should not have the check bit included."""
+    check = (11 - sum((8 - i) * int(n)
+                      for i, n in enumerate(number))) % 11
+    return 'X' if check == 10 else str(check)
+
+
+def validate(number):
+    """Checks to see if the number provided is a valid ISSN. This checks
+    the length and whether the check digit is correct."""
+    number = compact(number)
+    if not number[:-1].isdigit():
+        raise InvalidFormat()
+    if len(number) != 8:
+        raise InvalidLength()
+    if calc_check_digit(number[:-1]) != number[-1]:
+        raise InvalidChecksum()
+    return number
+
+
+def is_valid(number):
+    """Checks to see if the number provided is a valid ISSN. This checks
+    the length and whether the check digit is correct."""
+    try:
+        return bool(validate(number))
+    except ValidationError:
+        return False
+
+
+def format(number):
+    """Reformat the passed number to the standard format."""
+    number = compact(number)
+    return number[:4] + '-' + number[4:]
+
+
+def to_ean(number, issue_code='00'):
+    """Convert the number to EAN-13 format."""
+    number = '977' + validate(number)[:-1] + issue_code
+    return number + ean.calc_check_digit(number)