Method and device for matching regular expressions

Abstract

The embodiment of the invention provides a method and device for matching regular expressions. The method comprises the following steps of: firstly, inputting a message to be matched and a DFA (Deterministic Finite Automaton) state table, wherein the DFA state table comprises a state transition table including transition relationships between all state addresses and each state in the matching process of the regular expressions; secondly, judging a data type corresponding to the present state, wherein the data type includes a single-character Char type and a multi-character Str type, and the data corresponding to the Str type are a plurality of continuous characters; if the data type is the Str type, matching a plurality of character values in the current state of the message to be matchedand the matching condition, and when matched, shifting to the next state satisfying the matching condition; if the data type is the Char type, matching a single character value at the current state in the message to be matched and the matching condition, and when matched, shifting to the next state satisfying the matching condition; and when the next state is an accept state, finishing the matching process and outputting a success result of matching. The method for matching regular expressions has high matching speed and high efficiency and the space occupied by the DFA items is small.

Description

technical field [0001] The invention relates to the field of data processing, in particular to a regular expression matching method and device. Background technique [0002] Regular expression (Regular Expression) is a tool used to describe a specific string. Its syntax is rich, and it can accurately and flexibly describe strings with various complex characteristics. The regular expression engine can, according to the characteristics described by the regular expression, find out a subset of strings that meet the characteristics from a given set of strings. [0003] The regular expression engine has a very wide range of uses, such as text search and replacement, file retrieval, etc. Complete specific content identification and filtering, network monitoring, protocol identification, flow detection and flow control, attack protection, virus detection and other functions. [0004] Usually, regular expressions can be compiled to generate NFA (Nondeterministic Finite Automaton,...

AI Technical Summary

Problems solved by technology

[0007] Because the DFA table has complex rules (such as multiple .*), where . means any character and * means any number of occurrences, the DFA table item is relatively large and takes up a lot of storage space, so the DFA engine is processing this The matching speed will be slower when the DFA table is planted

Images