A structural matching engine for non-deterministic filtering operations is provided. The structural matching engine includes an active node processor (ANP) configured to process a state of an active list to determine possible future states of a non-deterministic finite automaton (NFA). The ANP processes the state according to rules. The structural matching engine includes an active list processor (ALP) configured to initiate a lookup for a token value corresponding to the state of the active list. The ALP provides a next sate of the active list to the ANP for processing according to the rules upon completion of the processing of the state by the ANP, wherein the possible future states of the NFA are linked by the ALP to form a target list, the target list stacked on top of the active list in a data structure. A processor and a method for filtering data associated with non-deterministic states are also included.