Patent Document ID: 7710988
Application ID: 11373228

Base Claim:
1. A structural matching engine for non-deterministic finite automaton filtering operations, comprising: 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 processing the state according to rules; and an active list processor (ALP) configured to initiate a lookup for a token value corresponding to the state of the active list, the ALP providing a next state 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 stack structure, wherein the structural matching engine is implemented in hardware.

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Claim 4:
4. The structural matching engine of claim 1 , wherein the stack structure is a walker stack and wherein stacks of the stack structure are added for each start token of a message being processed and stacks of the stack structure are removed for each end token of the message being processed.