IF-ELSE条件语句的翻译程序

//基于LL(1)法的条件语句语法语义分析程序 #include<iostream.h> #include<fstream.h> #include<string.h> #include<iomanip.h> #include<malloc.h> enum keyword{ $right_paren,$left_paren,$mul,$div,$add,$sub,$fenhao, $equal,$IF,$THEN,$ELSE,$greater,$less,$id,$num,$end}; typedef struct Token { keyword type; char ch; }Token; typedef enum{JUMP,JG,JL,equal,END,add,mul,sub,div}OpKind; typedef struct { int label;//标号 OpKind op;//操作符 char par1,par2;//操作数 union { char result;//结果 int address;//地址 }; }Quad; //四元式入口 #define MAX_TOKEN 256//Token表大小 #define MAX_QUAD 256//四元式数组大小 Token tokentable[MAX_TOKEN]; Quad quad[MAX_QUAD]; int token_index;//token表索引 int total_len;//token表有效长度 int quad_len;//四元式表有效长度 int quad_index;//四元式索引 Token cur; Token queue[10]; int label,k,one; //标记接口 char curchar;//存储当前待比较字符 char curtocmp;//存储当前栈顶字符 ifstream ins; int trueadd,falseadd,end; int table[5][8]={{1,0,0,0,0,1,0,0}, {0,1,1,0,0,0,1,1}, {1,0,0,0,0,1,0,0}, {0,1,1,1,1,0,1,1}, {1,0,0,0,0,1,0,0}}; //存储预测分析表，1为有产生式，0为没有 int i,j; int flag; struct Lchar { char char_ch; struct Lchar *next; }Lchar,*temp,*top,*base; int right;//定义开关项 bool initialize(char filename[255]);//文件打开初始化 bool accidence();//词法分析 void print();//输出单词表 void backpath(int,int);//回填出口 void ERROR(); void sentence();//分析语句 void boolean();// 分析E->id < id | id > id语句 bool nexttoken();//读下一单词 char newchar(); void push();//进队列 char dosome(void);//算法函数 void pushs(char pchar);//入栈函数 void pop(void);//出栈函数 void doforpush(int t);//根据数组下标计算的值产生式入栈 void changchartoint();//根据curchar,curtocmp转为数字以判断是否有产生式 void semantic();//语法语义分析 char LL1();//LL(1)文法分析 void printQuad();//输出四元式 void ERROR(char str[20]); void AD_ADDRESS(int nlabel,OpKind nop,char npar1,char npar2,int naddress); void AD_RESULT(int nlabel,OpKind nop,char npar1,char npar2, char nresult); void main() { cout<<" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "<<endl <<" @ 基于LL(1)法的条件语句语法语义分析程序 @ "<<endl <<" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ "<<endl; cout<<"输入您要编译文件的文件名(文件名.txt):"; char fname[100]; cin>>fname; if(!initialize(fname)) return; if(!accidence()) return; char ch; while(1) { if(ins.eof()) break; ins>>ch; } cout<<endl<<"词法分析结果如下:"; print(); cout<<endl; cout<<"词法分析结束。"<<endl<<endl; semantic(); //语法语义分析 cout<<endl<<"输出四元式:"<<endl; printQuad(); if(right==1) cout<<"分析成功"<<endl; else cout<<"分析失败"<<endl; cout<<"语法语义分析结束"<<endl; } char newchar() { char p; p=char(k); k++; return p; } //文件打开初始化 bool initialize(char filename[100]) { one=0; token_index=0; total_len=0; quad_len=0; quad_index=0; label=0; end=0; k=48; ins.open(filename,ios::nocreate | ios::in); if(ins.fail()) { cout<<"文件打开出错!"<<endl; return false; } return true; } //词法分析 bool accidence() { int k=0; char buf[16]; char ch; while(1) { ins>>ch; if(ins.fail()) break; while(ch==' ') { ins>>ch;} if(ch=='I') { ins>>buf; if(strcmp(buf,"F")==0) tokentable[total_len++].type=$IF; } else if(ch=='T') { ins>>buf; if(strcmp(buf,"HEN")==0) tokentable[total_len++].type=$THEN; } else if(ch=='E') { ins>>buf; if(strcmp(buf,"LSE")==0) tokentable[total_len++].type=$ELSE; } else if(ch=='>') { tokentable[total_len++].type=$greater; } else if(ch=='<') { tokentable[total_len++].type=$less; } else if(ch=='=') { tokentable[total_len++].type=$equal; } else if((ch>='A'&& ch<='Z' )|| (ch>='a' && ch<='z')) { tokentable[total_len].type=$id; tokentable[total_len++].ch=ch; } else if(ch>='0' && ch<='9') { tokentable[total_len].type=$num; tokentable[total_len++].ch =ch; } else switch (ch) {case '+' : tokentable[total_len].type=$add; tokentable[total_len++].ch =ch; break; case '-' : tokentable[total_len].type=$sub; tokentable[total_len++].ch =ch; break; case '/' : tokentable[total_len].type=$div; tokentable[total_len++].ch =ch; break; case '*' : tokentable[total_len].type=$mul; tokentable[total_len++].ch =ch; break; case ';' : tokentable[total_len].type=$fenhao; tokentable[total_len++].ch =ch; break; case '(' : tokentable[total_len].type=$left_paren; tokentable[total_len++].ch =ch; break; case ')' : tokentable[total_len].type=$right_paren; tokentable[total_len++].ch =ch; break; default:cout<<"!"<<endl; } } return true; } //语法语义分析 void semantic() { if(!nexttoken()) ERROR("s(0)"); cout<<"开始进行语法语义分析:"<<endl <<"所使用的产生式:"<<endl <<"<if语句> -> if E then S else S"<<endl <<"S->if E then else P2"<<endl <<"E->a>b"<<endl <<"P->x:=a*c"<<endl <<"P->x:=b*c"<<endl <<"语法语义分析过程如下:"<<endl; if(cur.type==$IF) { boolean();//分析布尔语句 if(!nexttoken()) ERROR("S(0)"); if(cur.type==$THEN) { backpath(trueadd,quad_len);//回填出口 sentence();//分析语句 end=quad_len; AD_ADDRESS(quad_len,JUMP,'-','-',end); //产生跳转地址的四元式 if(cur.type==$ELSE) { backpath(falseadd,quad_len); sentence(); backpath(end,quad_len); } else ERROR("S(else)"); } else { ERROR("S(then)"); } } else ERROR("S(if)"); AD_RESULT(quad_len,END,0,0,'-'); //产生数值语句的四元式 } //读下一单词 bool nexttoken() { if(token_index>=total_len) return false; if(tokentable[token_index].type==$fenhao) token_index++; cur.type=tokentable[token_index].type; cur.ch=tokentable[token_index].ch; token_index++; return true; } //进队列 void push() { one=0; while(tokentable[token_index].type!=$fenhao) { queue[one].type=tokentable[token_index].type; queue[one].ch=tokentable[token_index].ch; cout<<queue[one].ch; token_index++; one++; } queue[one].type=$end; queue[one].ch='#'; cout<<queue[one].ch; } //队列下一个字符 void next() { cur.type=queue[one].type; cur.ch =queue[one].ch ; one++; } // 分析E->id < id | id > id语句 void boolean() { char a,b; int c; if(!nexttoken()) ERROR("E(0)"); if(cur.type==$id||cur.type==$num) { a=cur.ch; if(!nexttoken()) ERROR("E(0)"); if(cur.type==$greater||cur.type==$less) { c=cur.type ; if(!nexttoken()) ERROR("E(0)"); if(cur.type==$id||cur.type==$num) b=cur.ch; else ERROR("E(id/num)"); if(c==$greater) { trueadd=quad_len-1; falseadd=quad_len; AD_ADDRESS(quad_len,JG,a,b,trueadd); AD_ADDRESS(quad_len,JUMP,0,0,falseadd); } else { trueadd=quad_len; falseadd=quad_len+1; AD_ADDRESS(quad_len,JL,a,b,trueadd); AD_ADDRESS(quad_len,JUMP,0,0,falseadd); } } else ERROR("E(id/num)"); } else ERROR("E(greater/less)"); } //分析语句 void sentence() { char rtn; char c; if(!nexttoken()) ERROR("S(0)"); if(cur.type==$id) { c=cur.ch; if(!nexttoken()) ERROR("S(0)"); if(cur.type!=$equal) ERROR("S(equal)"); push(); one=0; rtn=LL1(); AD_RESULT(quad_len,equal,rtn,'-',c); nexttoken(); while(cur.type==$id)