A regular expressions matching algorithm based on templates finite automata

When applying the method of the grouping rules to the problem of state explosion of the Deterministic Finite Automata (DFA), the efficiency of space compression significantly decreases with the increase of the quantity of the rules. Therefore, the paper proposes the Templates Finite Automata Grouping Algorithm (TFA), which divides rule sets into different groups based on templates of the rules. Each group is used to construct its corresponding matching engine. At the meantime, the number of rule subsets is altered according to the quantity of actual rules and the structure of a system to achieve better matching efficiency. Theoretical analysis and the experiments conducted indicate that comparing with the conventional grouping algorithms, the TFA requires far fewer groups at the relatively similar level of storage space compression; and comparing with other classical DFA improved algorithms, the TFA achieves shorter pretreatment time and demands smaller storage space with no noticeably decrease in the matching efficiency.