Research And Implementation Of Flight Intelligence Analysis Based On Regular Expressions

The intelligence analysis system play an important role in flight safety of the aircraft.This paper aims to achieve a intelligence analysis system base on regular expression.In the past,the intelligence analysis system is directly call the regular engine library to achieve regular matching,The disadvantage of this approach is that each call to the regular matching function must go through the process from the automaton configuration to the regular matching.Because of the regular expression that makes up all the flight intelligence fields is fixed,this paper we create our own regular engine based on DFA to achieve regular matching.In this way,the intelligence analysis system will be more efficient.In order to create an optimized DFA,first extends the Thompson algorithm to meet the regular meta-characters required by the system,then uses the extended Thompson algorithm to create the NFA and determine it to DFA.In order to compress the number of DFA states,this paper implements a DFA state minimization algorithm by eliminating unreachable states and merging indistinguishable states;In order to reduce the DFA transitions,this paper based on the fact that a state may arrive to the same purpose state under different excitation characters combination of the default edge length optimization strategy,then the optimized D~2FA algorithm is proposed.The test data shows that compared with the original D~2FA algorithm,the D~2FA algorithm after the second optimization has improved the compression rate of DFA by 4.3%.Finally,on the basis of optimized DFA,this paper designs a parsing algorithm based on regular expression for each meteorological message and air traffic announcement message;In particular,for AFTN message,this paper proposes a parsing algorithm based on context-free grammar and regular expression,so that all AFTN messages share a decoding function,greatly reducing the amount of parsing code.The results of this paper have been used in a actual air traffic control system,the design of the intelligence analysis subsystem is running well.