?? yujufanyi.cpp
字號:
#include <math.h>
#include <iostream.h>
#include <string.h>
int c,k,t=0;
struct shuzu{
char *result[8];
char *ag1[8];
char *op[8];
char *ag2[8];
};
shuzu quad[20];
char prog[80],token[8];
char ch;
int syn,p,m,n,sum,kk;
char *rwtab[6]={"begin","if","then","while","do","end"};
int yucu();
int statement();
char *expression();
char *term();
char *factor();
char *newterm(void);
void emit(char*result,char*ag1,char*op,char*ag2);
int scaner()
{
for(n=0;n<8;n++)
token[n]=0;
m=0;
ch=prog[p];
while(ch==' ') ch=prog[p++];
if((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z'))
{
while((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z')||(ch>='0'&&ch<='9'))
{
token[m++]=ch;
ch=prog[p++];
}
token[m++]='\0';
p--;
syn=10;
for(n=0;n<6;n++)
if(strcmp(token,rwtab[n])==0)
switch(n){
case 0:
syn=1;
break;
case 1:
syn=2;
break;
case 2:
syn=3;
break;
case 3:
syn=4;
break;
case 4:
syn=5;
break;
case 5:
syn=6;
break;
default:break;
}
}
else
if(ch>='0'&&ch<='9'){sum=0;
while(ch>='0'&&ch<='9')
{sum=sum*10+ch-'0';
ch=prog[p++];
}
p--;
syn=11;
}
else
switch(ch){
case '<':m=0;
token[m++]=ch;
ch=prog[p++];
if(ch=='>')
{syn=21;
token[m++]=ch;}
else if(ch=='=')
{
syn=22;
token[m++]=ch;
}
else {syn=20;p--;}
break;
case'>':m=0;
token[m++]=ch;
ch=prog[p++];
if(ch=='=')
{syn=24;
token[m++]=ch;}
else{
syn=23;
p--;
}
break;
case ':':m=0;
token[m++]=ch;
ch=prog[p++];
if(ch=='=')
{syn=18;
token[m++]=ch;
}
else{
syn=17;
p--;
}
break;
case '=':
syn=25;
token[0]=ch;
break;
case'+': syn=13;
token[0]=ch;
break;
case'-':
syn=14;
token[0]=ch;
break;
case'*':
syn=15;
token[0]=ch;
break;
case'/':
syn=16;
token[0]=ch;
break;
case ';':
token[0]=ch;
syn=26;
break;
case '(':
token[0]=ch;
syn=27;
break;
case ')':
token[0]=ch;
syn=28;
break;
case'#':
syn=0;
token[0]=ch;
break;
default:
syn=-1;
}
return syn;
}
int lrparser(){
int schain=0;
if(syn==1){
scaner();
schain=yucu();
if(syn==6){
scaner();
if(syn==0&&kk==0){
cout<<"success!";
kk=1;}
}
else {
if(kk!=1) cout<<"缺end,錯誤!";
kk=1;}
}
else{cout<<"缺begin錯誤!";kk=1;}
return schain;
}
int yucu(){
int schain=0;
schain=statement();
while(syn==26){
scaner();
schain=statement();
}
return schain;
}
int statement(){
char tt[8],eplace[8];
int schain=0;
switch(syn){
case 10:
strcpy(tt,token);
scaner();
if(syn==18){
scaner();
strcpy(eplace,expression());
emit(tt,eplace,"","");
schain=0;
}
else{
cout<<"error!缺少賦值號!";
}
break;
}
return schain;
}
char *expression(){
char *tp,*ep2,*eplace,*tt;
tp=new char[12];
ep2=new char [12];
eplace=new char [12];
tt=new char [12];
strcpy(eplace,term());
while(syn==13||syn==14){
switch(syn){
case 13:
tt[c]='+';
break;
case 14:
tt[c]='-';
break;
default:break;
}
scaner();
strcpy(eplace,term());
strcpy(tp,newterm());
emit(tp,eplace,tt,ep2);
strcpy(eplace,tp);
}
return eplace;
}
char *term(){
char *tp,*ep2,*eplace,*tt;
tp=new char [12];
ep2=new char [12];
eplace=new char [12];
tt=new char [12];
strcpy(eplace,term());
while(syn==15||syn==16){
switch(syn){
case 15:
tt[c]='*';
break;
case 16:
tt[c]='/';
break;
default:break;
}
scaner();
strcpy(eplace,term());
strcpy(tp,newterm());
emit(tp,eplace,tt,ep2);
strcpy(eplace,tp);
}
return eplace;
}
char *factor(){
char *fplace;
fplace=new char [12];
strcpy(fplace," ");
if(syn==10){
strcpy(fplace,token);
scaner();
}
else if(syn==11){
itoa(sum,fplace,10);
scaner();
fplace=expression();
if(syn==28)
scaner();
else{cout<<"')'error!";
kk=1;
}
}
else{
cout<<"'('error!";
kk=1;
}
return fplace;
}
char *newterm(void){
char*p;
char m[8];
p=new char [8];
k++;
itoa(k,m,10);
strcpy(p+1,m);
p[0]='t';
return p;
}
void emit(char*result,char*ag1,char*op,char*ag2){
quad[t].result[0]=result;
quad[t].ag1[0]=ag1;
quad[t].op[0]=op;
quad[t].ag2[0]=ag2;
t++;
}
void main(){
int i;
p=0;
cout<<"please input string:\n";
cin.getline(prog,80);
scaner();
do{
lrparser();
factor();
}while(kk!=1);
for(i=0;i<=20;i++)
cout<<"("<<quad[i].result<<","<<quad[i].op<<","<<quad[i].ag1<<","<<quad[i].ag2<<","<<endl;
}
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