该语义分析器能实现编译器的前端，适用于自上而下的语法分析。在语法分析的同时加进语义动作，实现一遍处理，能提高对编译原理课程的理解-Semantic Analyzer to achieve the compiler front-end for top-down parsing. At the same time in the analysis of syntax into semantic actions to deal with the realization of it, the compil