palo_alto_base.py 文件源码

def tag_delta(expression, tag_list):
        """Take in a tag expression and a list of tags and give the delta of tags to meet the expression

        :return tuple( list( "required tags" ),  list( "tuple of options" ) )
        """

        if tag_list is None:
            tag_list = []

        required_tags = []
        optional_tags = []

        def parse_and(tokens):
            args = tokens[0][0::2]
            extend_list = filter(lambda x: isinstance(x, str) and x not in tag_list, args)
            required_tags.extend(extend_list)

        def parse_or(tokens):
            args = tokens[0][0::2]
            append_list = filter(lambda x: isinstance(x, str) and x not in tag_list, args)
            if append_list == args:
                optional_tags.append(tuple(append_list))

        identifier = pp.Word(pp.alphanums + "_" + "-" + "'")

        expr = pp.infixNotation(identifier, [
            ("AND", 2, pp.opAssoc.LEFT, parse_and),
            ("OR", 2, pp.opAssoc.LEFT, parse_or),
            ("and", 2, pp.opAssoc.LEFT, parse_and),
            ("or", 2, pp.opAssoc.LEFT, parse_or),
        ])

        expr.parseString(expression)

        if expression and not required_tags and expression not in tag_list:
            # single tag in the expression
            required_tags.append(expression)

        return required_tags, optional_tags