From 85dd6f26be85f33986c2cd25c5a10cfdf4a5306c Mon Sep 17 00:00:00 2001
From: Sharoon Thomas <sharoon.thomas@openlabs.co.in>
Date: Tue, 18 Mar 2014 21:09:01 +0530
Subject: Add support for ISO6346

Add validation and creation of check digit for ISO6346 codes.

See: https://github.com/arthurdejong/python-stdnum/pull/9
---
 stdnum/iso6346.py | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 stdnum/iso6346.py

(limited to 'stdnum/iso6346.py')

diff --git a/stdnum/iso6346.py b/stdnum/iso6346.py
new file mode 100644
index 0000000..07d1a85
--- /dev/null
+++ b/stdnum/iso6346.py
@@ -0,0 +1,84 @@
+# iso6346.py - functions for handling ISO 6346
+#
+# Copyright (C) 2014 Openlabs Technologies & Consulting (P) Limited
+# Copyright (C) 2014 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
+
+"""ISO 6346 (International standard for container identification)
+
+ISO 6346 is an international standard covering the coding, identification and
+marking of intermodal (shipping) containers used within containerized
+intermodal freight transport. The standard establishes a visual identification
+system for every container that includes a unique serial number (with check
+digit), the owner, a country code, a size, type and equipment category as well
+as any operational marks. The standard is managed by the International
+Container Bureau (BIC).
+
+>>> validate('csqu3054383')
+'CSQU3054383'
+>>> validate('CSQU3054384')
+Traceback (most recent call last):
+    ...
+InvalidChecksum: ...
+"""
+
+import re
+import string
+
+from stdnum.exceptions import InvalidChecksum, InvalidFormat, InvalidLength, \
+    ValidationError
+from stdnum.util import clean
+
+
+_iso6346_re = re.compile('^\w{3}(U|J|Z|R)\d{7}$')
+
+
+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().upper()
+
+
+def calc_check_digit(number):
+    """Calculate check digit and return it for the 10 digit owner code and
+    serial number."""
+    number = compact(number)
+    alphabet = '0123456789A BCDEFGHIJK LMNOPQRSTU VWXYZ'
+    return str(sum(
+        alphabet.index(n) * pow(2, i)
+        for i, n in enumerate(number)) % 11)
+
+
+def validate(number):
+    """Validate the given number (unicode) for conformity to ISO 6346."""
+    number = compact(number)
+    if len(number) != 11:
+        raise InvalidLength()
+    if not _iso6346_re.match(number):
+        raise InvalidFormat()
+    if calc_check_digit(number[:-1]) != number[-1]:
+        raise InvalidChecksum()
+    return number
+
+
+def is_valid(number):
+    """Check whether the number conforms to the standard ISO6346. Unlike
+    the validate function, this will not raise ValidationError(s)."""
+    try:
+        return bool(validate(number))
+    except ValidationError:
+        return False
-- 
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