class Rules(list):
    """A list of rules for identifying effective top-level domains.
 
    Rules are formatted as described by the `Public Suffix List`_.
 
    >>> tlds = Rules()
 
    Add rules to the list using the ``Rules.load`` method:
 
    >>> tlds.load(['com', '*.org'])
    >>> 'com' in tlds
    True
    >>> 'example.com' in tlds
    False
    >>> 'example.org' in tlds
    True
 
    ``Rules.load`` will ignore comments and empty rules.  This allows the
    `Public Suffix List`_ to be loaded unmodified.
 
    >>> tlds.load(['// comment', '', '*.net'])
    >>> '// comment' in tlds
    False
    >>> '' in tlds
    False
    >>> 'example.net' in tlds
    True
 
    .. _`Public Suffix List`: http://publicsuffix.org/
 
    """
 
    def __contains__(self, domain):
        """Check if `domain` matches any of the rules."""
        if super(Rules, self).__contains__(domain): return True
        exception = '!%s' % domain
        if super(Rules, self).__contains__(exception): return False
        # TODO: The rules allow wildcards at any level of the domain; this
        #       only handles wildcards at the beginning of the domain.
        #       Fix that.
        wildcard = '*.%s' % '.'.join(domain.split('.')[1:])
        return super(Rules, self).__contains__(wildcard)
 
    def load(self, rules):
        if isinstance(rules, basestring):
            rules = [rules]
        for rule in rules:
            rule = rule.strip()
            if not rule or rule.startswith('//'): continue
            rule = rule.split()[0] # read only to the first white space
            self.append(rule)
 
 
if __name__ == '__main__':
    import doctest
    doctest.testmod()