编译原理语义分析程序设计

1、实验3 语义分析程序设计【实验目的】加深对语法制导翻译原理的理解，掌握将语法分析所识别的语法成分变换为中间代码的语义翻译方法。【实验内容】采用递归下降语法制导翻译法，对算术表达式、赋值语句进行语义分析并生成四元式序列。置初值调用scaner读下一个单词符号调用lrparser结束【设计思路】1、流程图输出四元式图2.1递归下降分析程序示意图2、源程序代码（1）scan.h /头文件-扫描程序#include#includechar prog80,token8;char ch;int syn,p,m,n,sum; /p是缓冲区prog的指针，m是token的指针char *rwtab6=begi

2、n,if,then,while,do,end;void scanner() /词法扫描程序memset(token,0,sizeof(token);/清空数组tokenm=0;while(ch= )+p;ch=progp; /读下一个字符;if(ch=a&ch=A&ch=a&ch=A&ch=0&ch=9)tokenm+=ch;+p;ch=progp;/读下一个字符;tokenm+=0;syn=10;for(n=0;n=0&ch=0&ch=9)sum=sum*10+ch-0;/将ch转换为数字+p;ch=progp;syn=11;elseswitch(ch)/其他字符情况case)syn=21;

3、+m;tokenm=ch;else if(ch=)syn=22;+m;tokenm=ch;elsesyn=20;break;case:token0=ch;+p;ch=progp;if(ch=)syn=24;token0=ch;elsesyn=23;break;case:token0=ch;+p;ch=progp;if(ch=)syn=18;+m;tokenm=ch;+p;ch=progp;elsesyn=17;break;case+:syn=13;token0=ch;ch=prog+p;break;case-:syn=14;token0=ch;ch=prog+p;break;case*:syn

4、=15;token0=ch;ch=prog+p;break;case/:syn=16;token0=ch;ch=prog+p;break;case=:syn=25;token0=ch;ch=prog+p;break;case;:syn=26;token0=ch;ch=prog+p;break;case(:syn=27;token0=ch;ch=prog+p;break;case):syn=28;token0=ch;ch=prog+p;break;case#:syn=0; token0=ch;ch=prog+p;break;default:syn=-1;（2）yuyi.cpp / 语法分析主程序

5、#include#includescan.hint kk=0,q=0,k=0;structchar result8;char agl8;char op8;char ag28;quad20;int lrparser();int yucu();int statement();char * expression(void);char * term();char * factor();char * newtemp(void);void emit(char *result,char *agl,char *op,char *ag2);void main()kk=0;rewind(stdin);memset

6、(prog,0,sizeof(prog);/清空数组progp=0;printf(n please input string:n);doch=getchar();progp+=ch;while(ch!=#);p=0;ch=prog0;scanner();lrparser();for(int i=0;iq;+i)printf(%s=%s%s%sn,quadi.result,quadi.agl,quadi.op,quadi.ag2);int lrparser()int schain=0;kk=0;if(1=syn)scanner();schain=yucu();if(6=syn)scanner()

7、;if(0=syn|0=kk)printf(success!n);elseif(kk!=1) printf(缺end!);kk=1;elseprintf(缺begin!);kk=1;return schain;int yucu() /语句串分析函数int schain=0;schain=statement();while(26=syn)scanner();schain=statement();return schain;int statement()char tt8,eplace8;int schain=0;switch(syn)case 10:strcpy(tt,token);scanner

8、();if(18=syn)scanner();strcpy(eplace,expression();emit(tt,eplace,);schain=0;else printf(缺赋值号!);kk=1;return schain;break;char * expression(void)/表达式分析函数char *tp,*ep2,*eplace,*tt;tp=(char *)malloc(12);ep2=(char *)malloc(12);eplace=(char *)malloc(12);tt=(char *)malloc(12);strcpy(eplace,term();while(13=

9、syn)|(14=syn)strcpy(tt,token);scanner();strcpy(ep2,term();strcpy(tp,newtemp();emit(tp,eplace,tt,ep2);strcpy(eplace,tp);return eplace;char *term(void)char *tp,*ep2,*eplace,*tt;tp=(char *)malloc(12);ep2=(char *)malloc(12);eplace=(char *)malloc(12);tt=(char *)malloc(12);strcpy(eplace,factor();while(15=

10、syn)|(16=syn)strcpy(tt,token);scanner();strcpy(ep2,factor();strcpy(tp,newtemp();emit(tp,eplace,tt,ep2);strcpy(eplace,tp);return eplace;char *factor(void)char *fplace;fplace=(char *)malloc(12);strcpy(fplace, );if(10=syn)strcpy(fplace,token);scanner();else if(11=syn)itoa(sum,fplace,10);scanner();else if(27=syn)scanner();fplace=expression();if(28=syn)scanner();elseprintf()错误!);kk=1;elseprintf(错误!);kk=1;return fplace;char * newtemp(void)char *p;char m8;p=(char *)malloc(8);k+;itoa(k,m,10);strcpy(p+1,m);p0=t;ret