編譯原理語義分析報告實驗報告材料

1、語義分析實驗報告1、 實驗目的：通過上機實習，加深對語法制導翻譯原理的理解，掌握將 語法分析所識別的語法成分變換為中間代碼的語義翻譯方法。2、 實驗要求：采用遞歸下降語法制導翻譯法，對算術(shù)表達式、賦值語句 進行語義分析并生成四元式序列。三、算法思想：1'設置語義過程。(1) emit(char *result,char *ag1 ,char *op,char *ag2)該函數(shù)的功能是生成一個三地址語 句送到四元式表中。四元式表的結(jié)構(gòu)如下：structchar result8;char ag18;char op8;char ag28;quad20;char*newtemp()該函數(shù)回送一

2、個新的臨時變量名，臨時變量名產(chǎn)生的順序為T1 ，T2，char *newtemp(void) char *p;char m8;p=(char *)malloc(8);k+;itoa(k,m,10); strcpy(p+1,m);p0= r；return(p);)2、函數(shù)Irparser在原來語法分析的基礎上插入相應的語義動作： 將輸入串翻譯成四元式序列。在實驗中我們只對表達式、賦值語句進 行翻譯。四、源程/予代碼：#include<stdio.h> #include<string.h> #include<iostream.h>#include<stdl

3、ib.h> struct char result12;char ag112;char op12;char ag212;quad;char prog80,token12;char ch;int syn,p,m=O,n,sum=O,kk; /p 是緩沖區(qū) prog 的指針、m 是 token 的指針char *rwtab6=''begin,1f,",thenM,Hwhile,；'do,；,endn;void scaner();char *factor(void);char *term(void);char *expression(void);int yucu

4、();void emit(char *result,char *ag1 ,char *op,char *ag2);char *newtemp();int statement();int k=0;void emit(char *result,char *ag1 ,char *op,char *ag2) (strcpy(quad.result,result);strcpy(quad.ag15ag1);strcpy(quad.op,op);strcpy(quad.ag2,ag2);cout«quad.result«,f=n«quad.ag1«quad.op&#

5、171;quad.ag2«endl; )char *newtemp() (char *p;char m12;p=(char *)malloc(12);k+;itoa(k5m510);strcpy(p+13m);pO=t； return (p);)void scaner()(for(n=0;n<8;n+) tokenn=NULL;ch=progp+;while(ch= *) (ch=progp;P+；Hf(ch>='a'&&ch<='z')|(ch>='A,&&ch<='Z&#

6、39;) (m=O;while(ch>=,0'&&ch<='9')|(ch>='a'&&ch<='z')|(ch>="A'&&ch<='Z') < tokenm+=ch; ch=progp+;token m+='O'P-；syn=10;for(n=0;n<6;n+)if(strcmp(token,rwtabn)=0)syn=n+1; break;)else if(ch>='0

7、9;&&ch<=,9') (sum=0;while(ch>='0'&&ch<='9') (sum=sum*10+chO1;ch=progp+;P-;syn=11;if(sum>32767) syn=-1;else switch(ch)(case,<f:m=0;tokenm+=ch;ch=progp+;if(ch='>f)(syn=21;tokenm+=ch;)else if(ch=,=,)(syn=22; tokenm+=ch;)elsesyn=23;P-;)break;case

8、,>,:m=0;tokenm+=ch;ch=progp+;if(ch='=,)(syn=24; tokenm+=ch;jelse(syn=20;P-；)break;case,:l:m=0;tokenm+=ch;ch=progp+;if(ch='=,)fsyn=18; tokenm+=ch;elsesyn=17;P-;)break;case,*,:syn=13;token0=ch;break; case7,:syn=14;token0=ch;break;casef+f:syn=15;token0=ch;break; case,J:syn=16;token0=ch;break

9、;case =f:syn=25;token0=ch;break;case,;l：syn=26;token0=ch;break; case'(,:syn=27;token0=ch;break;case,),:syn=28;token0=ch;break; case,#,:syn=0;token0=ch;break; default: syn=-1 ;break;int lrparser()coutvv” 調(diào)用 lrparserH«endl; int schain=O;kk=O;if(syn=1)(scaner(); schain=yucu();if(syn=6)scaner()

10、; if(syn=O && (kk=O) cout«Hsuccess!H«endl;)elseif(kk!=1)coutvv” 缺 end!”vvendl;kk=1;)elsecoutvv” 缺 begin!"«endl;kk=1; return(schain);int yucu()“coutvv” 調(diào)用 yucu"«endl;int schain=O;schain=statement();while(syn=26)(scaner();schain=statement();)return(schain);int sta

11、tement()coutvv” 調(diào)用 statement"«endl;char *eplace,*tt;eplace=(char *)malloc(12);tt=(char *)malloc(12);int schain=O;switch(syn)(case 10:strcpy(tt,token);scaner();if(syn=18)scaner();strcpy(eplace,expression();emit(tt5eplace；n,；n,);schain=O;elsecoutvv”缺少賦值符r«endl;kk=1;return(schain);break;

12、return(schain);char *expression(void)char *tp,*ep25*eplace,*tt; tp=(char *)malloc(12); ep2=(char *)malloc(12); eplace=(char*)malloc(12); tt =(char *)malloc(12); strcpy(eplace,term ();if(syn=15)strcpy(tt,H+,f); elsewhile(syn=15)|(syn=16)/調(diào)用term分析產(chǎn)生表達式計算的第一項eplacestrcpy(tt/,J,); scaner();strcpy(ep2,te

13、rm();strcpy(tp,newtemp();emit(tp,eplace,tt,ep2);strcpy(eplace,tp);/調(diào)用term分析產(chǎn)生表達式計算的第二項ep2調(diào)用newtemp產(chǎn)生臨時變量tp存儲計算結(jié)果/生成四元式送入四元式表»return(eplace);char *term(void)/ coutvv” 調(diào)用 termH«endl; char *tp/ep2,*eplace,*tt; tp=(char *)malloc(12); ep2=(char*)malloc(12); eplace=(char *)malloc(12); tt=(char *

14、)malloc(12); strcpy(eplace,factor();while(syn=13)|(syn=14) df(syn=13)strcpy(tt,'*n); else strcpy(tt/7"); scaner();strcpy(ep2,factor(); strcpy(tp,newtemp(); emit(tp,eplace,tt,ep2); strcpy(eplace,tp);)return(eplace);/調(diào)用factor分析產(chǎn)生表達式計算的第二項ep2 char *factor(void)調(diào)用newtemp產(chǎn)生臨時變量tp存儲計算結(jié)果char *fpla

15、ce;生成四元式送入四元式表fplace=(char *)malloc(12); strcpy(fplace,flt);if(syn=1O)strcpy(fplace,token);/將標識符token的值賦給fplacescaner();else if(syn=11)dtoa(sum,fplace,10); scaner();)else if(syn=27) scaner();fplace=expression(); 調(diào)用 expression if(syn=28) 分析返回表達式的值scaner();else(cout«n 缺)錯誤!”vvendl;kk=1;)elsecout«"缺(錯誤!"«endl;kk=1;)return(fplace);void main()(P=o；coutvv” 語義分析程序 *-«endl;cout«,fPlease input string:n«endl; docin.get(ch); prog