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@@ -3,36 +3,67 @@ import pyparsing as pp
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class QueryParser:
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def __init__(self):
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+ """
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+ Constructs a parser for all named queries using PyParsing.
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+ """
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# TODO: allow lists as input, like: ipaddress(macaddress in [1,2,3])
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extractor = pp.Keyword("random") ^ pp.Keyword("first") ^ pp.Keyword("last")
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+
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# Valid selectors - except "avg", because not all attributes can be combined with it
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selector_no_avg = pp.Keyword("most_used") ^ pp.Keyword("least_used") ^ pp.Keyword("all")
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+
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+ # All attributes that cannot be combined with "avg"
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attributes_no_avg = pp.Keyword("ipaddress") ^ pp.Keyword("macaddress") ^ pp.Keyword("portnumber") ^\
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pp.Keyword("protocolname") ^ pp.Keyword("winsize") ^ pp.Keyword("ipclass")
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+ # All attributes that can be combined with "avg"
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attributes_avg = pp.Keyword("ttlvalue") ^ pp.Keyword("mssvalue") ^\
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pp.Keyword("pktssent") ^ pp.Keyword("pktsreceived") ^ pp.Keyword("mss") ^\
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pp.Keyword("kbytesreceived") ^ pp.Keyword("kbytessent")
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+ # Collection of all attributes for simpler specification
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attributes_all = attributes_no_avg ^ attributes_avg
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+
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+ # Simple selector + attribute query, only allowing "avg" with compatible attributes
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simple_selector_query = (selector_no_avg + pp.Suppress("(") + attributes_all + pp.Suppress(")")) ^\
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(pp.Keyword("avg") + pp.Suppress("(") + attributes_avg + pp.Suppress(")"))
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+ # Selectors for parameterized queries - they are replaced in the result to avoid ambiguity
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param_selectors = pp.Keyword("ipaddress").setParseAction(pp.replaceWith("ipaddress_param")) ^\
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pp.Keyword("macaddress").setParseAction(pp.replaceWith("macaddress_param"))
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+ # All operators allowed in parameterized queries
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operators = pp.Literal("<=") ^ pp.Literal("<") ^ pp.Literal("=") ^\
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pp.Literal(">=") ^ pp.Literal(">") ^ pp.CaselessLiteral("in")
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+
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+ # Placeholder for nesting in parameterized queries
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expr = pp.Forward()
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+
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+ # One "attribute-operator-value" triplet. Value can be alphanumeric plus dot and colon, or a nested query
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comparison = pp.Group(attributes_all + operators + (pp.Word(pp.alphanums + ".:") ^ expr))
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+
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+ # A full parameterized query, consisting of a parameterized selector and a comma-separated list of comparisons
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parameterized_query = param_selectors + pp.Suppress("(") + pp.Group(pp.delimitedList(comparison)) + pp.Suppress(")")
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+ # Combination of simple and parameterized queries
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all_selector_queries = (simple_selector_query ^ parameterized_query)
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+
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+ # All queries can be combined with an extractor
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extractor_selector_query = extractor + pp.Suppress("(") + all_selector_queries + pp.Suppress(")")
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+ # Queries can be used with an extractor or without
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named_query = (extractor_selector_query ^ all_selector_queries)
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+
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+ # The placeholder can be replaced with any query
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expr << pp.Group(named_query)
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+
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+ # Make sure all queries end with a semicolon, and we're done
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self.full_query = named_query + pp.Suppress(";")
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def parse_query(self, querystring: str) -> pp.ParseResults:
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+ """
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+ Parses the passed query with a pre-constructed parser.
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+ :param querystring: The named query to be executed
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+ :return: A ParseResults-object, which essentially is a list of tokens
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+ """
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return self.full_query.parseString(querystring)
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