flex和bison在软PLC编译器中的应用

Application of flex and bison in compiler for SoftPLC

软PLC(可编程逻辑控制器)编译器是软PLC开发系统中的重要部分,同时也是整个开发系统中实现难度最大的部分。flex(快速词法分析发生器)和bison是优秀的词法扫描和语法分析工具,二者已经成为标准的Unix实用程序。文章介绍了在Linux系统下,应用flex和bison对符合IEC61131标准的指令表语言进行词法和语法分析的详细过程,给出了主要的代码片段,并通过实例进行了验证,证明了方法的正确性和可行性。

The SoftPLC＇ （Programmable Logic Controller）compiler is the most important and difficult part of the SoftPLC＇s development.flex（Fast Lexical Analyzer Generator） and bison are outstanding tools for lexical and syntactic analyzing.The research is based on Linux operating system.This paper presents the detail process of using flex and bison to analyze the Instruction List （IL）,which is canonical and ordained by IEC61131-3.The validity and feasibility of the method given in the paper are testified with some examples.