Esempio n. 1
0
class Query(Composer):
    '''
        Finds a match for the LHS.
    '''
    def __init__(self, LHS):
        '''
            Finds a match for the LHS.
            @param LHS: The pre-condition pattern (LHS + NACs).
        '''
        super(Query, self).__init__()
        self.M = Matcher(condition=LHS, max=1)
        self.I = Iterator(max_iterations=1)
    
    def packet_in(self, packet):
        self.exception = None
        self.is_success = False
        # Match
        packet = self.M.packet_in(packet)
        if not self.M.is_success:
            self.exception = self.M.exception
            return packet
        # Choose the only match
        packet = self.I.packet_in(packet)
        if not self.I.is_success:
            # Clean the packet: required since there is no Rewriter in a Query
            if  len(packet.match_sets[self.I.condition].matches) == 0:
                del packet.match_sets[self.I.condition]
            self.exception = self.I.exception
            return packet
        # Output success packet
        self.is_success = True
        return packet
Esempio n. 2
0
class LRule(Composer):
    '''
        Applies an inner rule for each match of the LHS.
    '''
    def __init__(self, LHS, inner_rule, max_iterations=INFINITY):
        '''
            Applies an inner rule for each match of the LHS.
            @param LHS: The pre-condition pattern (LHS + NACs).
            @param inner_rule: The rule to apply in the loop.
            @param max_iterations: The maximum number of matches of the LHS.
        '''
        super(LRule, self).__init__()
        self.M = Matcher(condition=LHS, max=max_iterations)
        self.I = Iterator(max_iterations=max_iterations)
        self.inner_rule = inner_rule
    
    def packet_in(self, packet):
        self.exception = None
        self.is_success = False
        # Match
        packet = self.M.packet_in(packet)
        if not self.M.is_success:
            self.exception = self.M.exception
            return packet
        # Choose the first match
        packet = self.I.packet_in(packet)
        if not self.I.is_success:
            self.exception = self.I.exception
            return packet
        while True:
            # Apply the inner rule
            packet = self.inner_rule.packet_in(packet)
            if not self.inner_rule.is_success:
                if self.inner_rule.exception:
                    self.exception = self.inner_rule.exception
                    return packet
            # Clean the packet: required since there is no Rewriter in a Query
            if  len(packet.match_sets[self.I.condition].matches) == 0:
                del packet.match_sets[self.I.condition]
            # Choose another match
            packet = self.I.next_in(packet)
            # No more iterations are left
            if not self.I.is_success:
                if self.I.exception:
                    self.exception = self.I.exception
                else:
                    # Output success packet
                    self.is_success = True
                return packet
Esempio n. 3
0
class ARule(Composer):
    """
        Applies the transformation on one match.
    """

    def __init__(self, LHS, RHS):
        """
            Applies the transformation on one match.
            @param LHS: The pre-condition pattern (LHS + NACs).
            @param RHS: The post-condition pattern (RHS).
        """
        super(ARule, self).__init__()
        self.M = Matcher(condition=LHS, max=1)
        self.I = Iterator(max_iterations=1)
        self.W = Rewriter(condition=RHS)

    def packet_in(self, packet):
        self.exception = None
        self.is_success = False
        # Match
        packet = self.M.packet_in(packet)
        if not self.M.is_success:
            self.exception = self.M.exception
            return packet
        # Choose the only match
        packet = self.I.packet_in(packet)
        if not self.I.is_success:
            self.exception = self.I.exception
            return packet
        # Rewrite
        packet = self.W.packet_in(packet)
        if not self.W.is_success:
            self.exception = self.W.exception
            return packet
        # Output success packet
        self.is_success = True
        return packet