东北大学编译原理实验3

编译原理程序设计实验报告——四元式生成班级：计算机1507班姓名：罗艺博学号：20154377一、实验目标：利用上次实验所编写的语法分析器，完成算术表达式四元式翻译器的设计。

二、实验内容：1.概要设计：2.流程图主程序Z子程序E子程序T子程序F 3.关键函数//主程序int ParserPlus(){is = 0; //初始化flag = 0;qt = qToken.front(); //Next(w)qreal = qTreal.front();SubE();if(qt==50&&flag==0){cout << "语法正确！" << endl;cout << endl;cout << "生成的四元式如下：" << endl;}else if(flag != 0)return 1;else{flag = 1;cout << "语法错误(err 1)！" << endl;return flag;}//cout<<"myQT.size="<<myQT.size()<<endl;for(int k=0;k<myQT.size();k++) //输出四元式{myQT[k].printQT();}return 0;}//子程序Eint SubE(){SubT();while(qt==60||qt==61){if(qt == 60) //GEQ(+){Nextword();SubT();char c = '+';GEQ(c);}else if(qt == 61) //GEQ(-){Nextword();SubT();char c = '-';GEQ(c);}}return 0;}//子程序Tint SubT(){SubF();while(qt==70||qt==71){if(qt == 70) //GEQ(*){Nextword();SubF();char c = '*';GEQ(c);}else if(qt == 71) //GEQ(/){Nextword();SubF();char c = '/';GEQ(c);}}return 0;}//子程序Fint SubF(){qtw = qt/10;if(qtw==1||qtw==2) //为i的情况下{sem.push(qt);qsem.push(qreal);Nextword();}else if(qtw == 3) //为(的情况下{Nextword();//cout<<qreal<<"1"<<endl;SubE();qtw = qt/10; //若无qtw仍为3//cout<<qreal<<"2"<<endl;//cout<<qt<<"###"<<qtw<<endl;if(qtw == 4) //若为){Nextword();}else{flag = 3;cout << "语法错误(err 3)！" << endl;return flag;}}else{flag = 2;cout << "语法错误(err 2)！" << endl;return flag;}return 0;}//创建临时变量int Newtemp(){int i = 0;for(i=0; i<100; i++){if(used[i] == 0){used[i] = i+1;return i; //返回t编号i}}}//生成四元式void GEQ(char c){string el2 = qsem.top();qsem.pop();sem.pop();string el1 = qsem.top();qsem.pop();sem.pop();int tt = Newtemp();sem.push(10);string treal = "t";treal += to_string(tt);qsem.push(treal);Send(c, el1, el2, treal);}//将四元式作为类对象储存void Send(char s, string e1, string e2,string t) {myQT.push_back(QT(s,e1,e2,t));}源程序代码：（加入注释）int ParserPlus() //主程序{is = 0; //初始化flag = 0;qt = qToken.front(); //Next(w)qreal = qTreal.front();SubE();if(qt==50&&flag==0){cout << "语法正确！" << endl;cout << endl;cout << "生成的四元式如下：" << endl;}else if(flag != 0)return 1;else{flag = 1;cout << "语法错误(err 1)！" << endl;return flag;}//cout<<"myQT.size="<<myQT.size()<<endl;for(int k=0;k<myQT.size();k++) //输出四元式{myQT[k].printQT();}return 0;}int SubE() //子程序E{SubT();while(qt==60||qt==61){if(qt == 60) //GEQ(+){Nextword();SubT();char c = '+';GEQ(c);}else if(qt == 61) //GEQ(-){Nextword();SubT();char c = '-';GEQ(c);}}return 0;}int SubT() //子程序T{SubF();while(qt==70||qt==71){if(qt == 70) //GEQ(*){Nextword();SubF();char c = '*';GEQ(c);}else if(qt == 71) //GEQ(/){Nextword();SubF();char c = '/';GEQ(c);}}return 0;}int SubF() //子程序F{qtw = qt/10;if(qtw==1||qtw==2) //为i的情况下{sem.push(qt);qsem.push(qreal);Nextword();}else if(qtw == 3) //为(的情况下{Nextword();//cout<<qreal<<"1"<<endl;SubE();qtw = qt/10; //若无qtw仍为3//cout<<qreal<<"2"<<endl;//cout<<qt<<"###"<<qtw<<endl;if(qtw == 4) //若为){Nextword();}else{flag = 3;cout << "语法错误(err 3)！" << endl;return flag;}}else{flag = 2;cout << "语法错误(err 2)！" << endl;return flag;}return 0;}void Nextword() //NEXT(w){qToken.pop();qt = qToken.front();qTreal.pop();//cout<<"!!!"<<qTreal.size()<<endl;qreal = qTreal.front();}#include <iostream>#include <cstdlib>#include <string.h>#include <queue>#include <stack>#include <vector>using namespace std;char ch; //当前字符int is; //处理到当前字符串第几个int it; //token串第几个char str[100]; //输入字符串char token[5]; //用于生成tokenint state; //词法分析此状态int statebefore; //词法分析前状态int code;int code1;int code2;int qt; //语法分析存放当前token(word) string qreal; //四元式用int qtw; //判断qt属于哪种字符int flag; //用于存放语法错误原因int lexer; //存放Lexer函数的返回值int parser; //存放Parser函数的返回值int used[50] = {0}; //存放临时变量char *PT0[2] = {"+", "-"};char *PT1[2] = {"*", "/"};char *PT2[1] = {"("};char *PT3[1] = {")"};char *PT4[1] = {"#"};queue<int> qToken;queue<string> qTreal; //四元式用存放真正的字符stack<int> sem; //语义栈stack<string> qsem; //四元式用存放真正的字符int IsAlpha(char c); //判断是否为字母int IsNum(char c); //判断是否为数字int IsPT0(char c); //判断是否为‘+’，‘-’int IsPT1(char c); //判断是否为‘*’，‘/’int state_change(int sta, char c);int state_to_code(int stabe, char* tok);void Nextword(); //NEXT(w)void GEQ(char c); //生成四元式void Send(char s, string e1, string e2,string t); //存四元式int SubE(); //子程序Eint SubT(); //子程序Tint SubF(); //子程序Fint Lexer(); //词法分析器int ParserPlus(); //语法分析器改进版class QTpublic :QT(char s, string e1, string e2, string t):symbol(s),element1(e1),element2(e2),ttemporary(t){} //设置四元式~QT(){}void printQT() //打印四元式{cout<<"( "<<symbol<<" "<<element1<<" "<<element2<<" "<<ttemporary<<" )"<<endl;}private:char symbol; //符号变量1 变量2 临时变量string element1;string element2;string ttemporary;};vector<QT> myQT; //将类对象放入向量，便于储存和最后的输出int main(){cout << "请输入算术表达式，以‘#’号结束。