广州大学学生实验报告一、实验目的学生运用编译原理的知识在实验技能和方法小组设计实验方案并加以实现。

二、基本知识1、完整的编译过程2、LR分析法三、实验环境1、Windows操作系统2、C++语言四、实验要求运用编译原理知识，经检验，该程序能正确运行。

五、实验内容完成一个相对完整的编译器，该编译完成对变量类型（整数/浮点数）定义、赋值、四则运算、逻辑运算、跳转与循环控制功能。

其输入是源程序（参见“一个四则运算源程序示例”），输出是所有变量的最终值。

要求：（1）输入任意一个正确的文法G[S]，都能分析，并得出一个等价的LL(1)文法G[E];（2）根据该LL(1)文法G[E]的文法规则建立LL(1)分析表；（3）输出输入串分析过程。

其分析过程。

六、实验代码及实验截图实验代码如下：（2）根据该LL(1)文法G[E]的文法规则建立LL(1)分析表；（3）输出输入串分析过程。

其分析过程。

#define _CRT_SECURE_NO_DEPRECATE#include <iostream>#include <cstring>#include <cstdio>#include <algorithm>#include <cstdlib>#include <vector>#include <string>#include <cctype>#include <map>#include <set>#include <stack>#define MAX 507using namespace std;map<string, set<char> > first;map<string, set<char> > follow;map<string, int> VN_dic;vector<WF> VN_set;bool used[MAX];class WF{public:string left;set<string> right;WF(char s[]){left = s;}void print(){printf("%s->", left.c_str());set<string>::iterator it = right.begin();if (right.begin() != right.end()){printf("%s", it->c_str());it++;}for (; it != right.end(); it++)printf("|%s", it->c_str());puts("");}void insert(char s[]){right.insert(s);}};void dfs(int x){if (used[x]) return;used[x] = 1;string& left = VN_set[x].left;set<string>& right = VN_set[x].right;set<string>::iterator it = right.begin();for (; it != right.end(); it++)for (int i = 0; i < it->length(); i++){if (!isupper(it->at(i)) && it->at(i) != '\''){first[left].insert(it->at(i));break;}if (isupper(it->at(i))){int y;if (i != it->length() - 1 && it->at(i + 1) == '\'')y = VN_dic[it->substr(i, 2)] - 1;else y = VN_dic[it->substr(i, 1)] - 1;string& tleft = VN_set[y].left;dfs(y);set<char>& temp = first[tleft];set<char>::iterator it1 = temp.begin();bool flag = true;for (; it1 != temp.end(); it1++){if (*it1 == '~') flag = false;first[left].insert(*it1);}if (flag) break;}else continue;}}void make_first(){memset(used, 0, sizeof(used));for (int i = 0; i < VN_set.size(); i++)dfs(i);#define DEBUG#ifdef DEBUGputs("***************FIRST集***********************");map<string, set<char> >::iterator it = first.begin();for (; it != first.end(); it++){printf("FIRST(%s)={", it->first.c_str());set<char> & temp = it->second;set<char>::iterator it1 = temp.begin();bool flag = false;for (; it1 != temp.end(); it1++){if (flag) printf(",");printf("%c", *it1);flag = true;}puts("}");}#endif}void append(const string& str1, const string& str2){set<char>& from = follow[str1];set<char>& to = follow[str2];set<char>::iterator it = from.begin();for (; it != from.end(); it++)to.insert(*it);}void make_follow(){while (true){bool goon = false;for (int i = 0; i < VN_set.size(); i++){string& left = VN_set[i].left;set<string>& right = VN_set[i].right;set<string>::iterator it = right.begin();for (; it != right.end(); it++){bool flag = true;const string& str = *it;for (int j = it->length() - 1; j >= 0; j--){if (str[j] == '\''){int x = VN_dic[it->substr(j - 1, 2)] - 1;if (flag){int tt = follow[it->substr(j - 1, 2)].size();append(left, it->substr(j - 1, 2));int tt1 = follow[it->substr(j - 1, 2)].size();if (tt1 > tt) goon = true;if (!VN_set[x].right.count("~"))flag = false;}for (int k = j + 1; k < it->length(); k++){if (isupper(str[k])){string id;if (k != it->length() - 1 && str[k + 1] == '\'')id = it->substr(k, 2);else id = it->substr(k, 1);set<char>& from = first[id];set<char>& to = follow[it->substr(j - 1, 2)];int tt = to.size();set<char>::iterator it1 = from.begin();for (; it1 != from.end(); it1++)if (*it1 != '~')to.insert(*it1);int tt1 = follow[it->substr(j - 1, 2)].size();if (tt1 > tt) goon = true;if (!VN_set[VN_dic[id] - 1].right.count("~"))break;}else if (str[k] != '\''){int tt = follow[it->substr(j - 1, 2)].size();follow[it->substr(j - 1, 2)].insert(str[k]);int tt1 = follow[it->substr(j - 1, 2)].size();if (tt1 > tt)goon = true;break;}else continue;}j--;}else if (isupper(str[j])){int x = VN_dic[it->substr(j, 1)] - 1;if (flag){int tt = follow[it->substr(j, 1)].size();append(left, it->substr(j, 1));if (!VN_set[x].right.count("~"))flag = false;int tt1 = follow[it->substr(j, 1)].size();if (tt1 > tt) goon = true;}for (int k = j + 1; k < it->length(); k++){if (isupper(str[k])){string id;if (k != it->length() - 1 && str[k + 1] == '\'')id = it->substr(k, 2);else id = it->substr(k, 1);set<char>& from = first[id];set<char>& to = follow[it->substr(j, 1)];set<char>::iterator it1 = from.begin();int tt = follow[it->substr(j, 1)].size();for (; it1 != from.end(); it1++)if (*it1 != '~')to.insert(*it1);int tt1 = follow[it->substr(j, 1)].size();if (tt1 > tt) goon = true;if (!VN_set[VN_dic[id] - 1].right.count("~"))break;}else if (str[k] != '\''){int tt = follow[it->substr(j, 1)].size();follow[it->substr(j, 1)].insert(str[k]);int tt1 = follow[it->substr(j, 1)].size();if (tt1 > tt) goon = true;break;}else continue;}}else flag = false;}}}if (!goon) break;}#define DEBUG#ifdef DEBUGputs("****************FOLLOW集**********************");map<string, set<char> >::iterator it = follow.begin();for (; it != follow.end(); it++){printf("FOLLOW(%s)={", it->first.c_str());set<char> & temp = it->second;temp.insert('#');set<char>::iterator it1 = temp.begin();bool flag = false;for (; it1 != temp.end(); it1++){if (flag) printf(",");printf("%c", *it1);flag = true;}puts("}");}#endif}vector<map<char, string> > predict_table;//检查一个字符是否属于一个字符串的FIRST集合bool check_first(const string& text, char ch){for (int i = 0; i < text.length(); i++){bool hasEmpty = false;if (!isupper(text[i]) && text[i] != '\''){if (text[i] != ch) return false;else return true;}else if (isupper(text[i])){string temp;if (i != text.length() - 1 && text[i + 1] == '\'')temp = text.substr(i, 2);elsetemp = text.substr(i, 1);set<char>& dic = first[temp];set<char>::iterator it = dic.begin();for (; it != dic.end(); it++){if (*it == '~') hasEmpty = true;if (*it == ch) return true;}if (!hasEmpty) break;}else continue;}return false;}//检查一个字符是否属于一个字符串的FOLLOW集合bool check_follow(const string& text, char ch){set<char>& dic = follow[text];set<char>::iterator it = dic.begin();for (; it != dic.end(); it++)if (*it == ch) return true;return false;}void make_table(){map<char, string> temp;vector<char> letter;bool vis[500];memset(vis, 0, sizeof(vis));for (int i = 0; i < VN_set.size(); i++){set<string>& right = VN_set[i].right;set<string>::iterator it = right.begin();for (; it != right.end(); it++)for (int j = 0; j < it->length(); j++)if (!isupper(it->at(j)) && it->at(j) != '\''){if (vis[it->at(j)]) continue;vis[it->at(j)] = true;letter.push_back(it->at(j));}}for (int i = 0; i < VN_set.size(); i++){temp.clear();string& left = VN_set[i].left;set<string>& right = VN_set[i].right;set<string>::iterator it = right.begin();for (; it != right.end(); it++)for (int j = 0; j < letter.size(); j++){//cout << *it << " " << letter[j] << endl;if (check_first(*it, letter[j])){//cout << "YES" << endl;temp[letter[j]] = *it;}if (it->at(0) == '~' && check_follow(left, letter[j]))temp[letter[j]] = *it;}predict_table.push_back(temp);}#define DEBUG#ifdef DEBUGfor (int i = 0; i <= (letter.size() + 1) * 10; i++)printf("-");puts("");printf("|%9s", "|");for (int i = 0; i < letter.size(); i++)printf("%5c%5s", letter[i], "|");puts("");for (int i = 0; i <= (letter.size() + 1) * 10; i++)printf("-");puts("");for (int i = 0; i < VN_set.size(); i++){printf("|%5s%4s", VN_set[i].left.c_str(), "|");for (int j = 0; j < letter.size(); j++)if (predict_table[i].count(letter[j]))printf("%7s%3s", predict_table[i][letter[j]].c_str(), "|");else printf("%10s", "|");puts("");for (int i = 0; i <= (letter.size() + 1) * 10; i++)printf("-");puts("");}#endif}void print(int steps, stack<string> stk, string src, string wf, int x){printf("%-10d", steps);string out = "";while (!stk.empty()){out = stk.top() + out;stk.pop();}printf("#%-9s", out.c_str());out = "";for (int i = x; i < src.length(); i++)out += src[i];printf("%-10s", (out + "#").c_str());printf("%-10s\n", wf.c_str());}void analyse(const string& src){stack<string> stk;stk.push("E");int steps = 0;int idx = 0;printf("%-10s%-10s%-10s%-10s\n", "步骤", "符号栈", "输入串", "所用产生式");while (!stk.empty()){string u = stk.top();string tmp = "";stk.pop();if (!isupper(u[0])){if (idx == src.length() && u[0] == '~');else if (src[idx] == u[0])idx++;}else{int x = VN_dic[u] - 1;tmp = predict_table[x][src[idx]];for (int i = tmp.length() - 1; i >= 0; i--){if (tmp[i] == '\''){string v = tmp.substr(i - 1, 2);stk.push(v);i--;}else{string v = tmp.substr(i, 1);stk.push(v);}}tmp = u + "->" + tmp;}print(steps++, stk, src, tmp, idx);}}int main(){int n;char s[MAX];while (cin >> n){for (int i = 0; i < n; i++){cin >> s;int len = strlen(s), j;for (j = 0; j < len; j++)if (s[j] == '-') break;s[j] = 0;if (!VN_dic[s]){VN_set.push_back(s);VN_dic[s] = VN_set.size();}int x = VN_dic[s] - 1;VN_set[x].insert(s + j + 2);}make_first();make_follow();make_table();string in = "i*i+i";analyse(in);}}实验截图如下：输入串First集Follow集分析过程七、实验分析本实验是综合实验，输入文法后，将其放入容器进行处理，完成输入操作。