app/django/utils/checksums.py
author Sverre Rabbelier <srabbelier@gmail.com>
Sun, 07 Dec 2008 17:02:10 +0000
changeset 705 0ab17e14df95
parent 54 03e267d67478
permissions -rw-r--r--
Move document sidebar entries extraction to document.View This way other modules can benefit from the same logic. Also make use of the sidebar.getSidebarMenu method so that getMenusForScope is no longer specific to full menu's. Patch by: Sverre Rabbelier

"""
Common checksum routines (used in multiple localflavor/ cases, for example).
"""

__all__ = ['luhn',]

LUHN_ODD_LOOKUP = (0, 2, 4, 6, 8, 1, 3, 5, 7, 9) # sum_of_digits(index * 2)

def luhn(candidate):
    """
    Checks a candidate number for validity according to the Luhn
    algorithm (used in validation of, for example, credit cards).
    Both numeric and string candidates are accepted.
    """
    if not isinstance(candidate, basestring):
        candidate = str(candidate)
    try:
        evens = sum([int(c) for c in candidate[-1::-2]])
        odds = sum([LUHN_ODD_LOOKUP[int(c)] for c in candidate[-2::-2]])
        return ((evens + odds) % 10 == 0)
    except ValueError:  # Raised if an int conversion fails
        return False