/*
* @Author: cos
* @Date: 2022-04-12 23:03:36
* @LastEditTime: 2022-04-13 01:32:58
* @LastEditors: cos
* @Description:
* @FilePath: \CS\experiment_2\main.cpp
*/
#include <iostream>
#include <string>
#include <fstream>
#include <vector>
#include <cstring>
using namespace std;
const string ExpFileName = "./exp.txt";
char analyeStack[20]; /*分析栈*/
char restStack[20]; /*剩余栈*/
const string v1 = "i+*()#"; /*终结符 */
const string v2 = "EGTSF"; /*非终结符 */
int top, ridx, len; /*len为输入串长度 */
struct type { /*产生式类型定义 */
char origin; /*产生式左侧字符 大写字符 */
string array; /*产生式右边字符 */
int length; /*字符个数 */
type():origin('N'), array(""), length(0) {}
void init(char a, string b) {
origin = a;
array = b;
length = array.length();
}
};
type e, t, g, g1, s, s1, f, f1; /* 产生式结构体变量 */
type C[10][10]; /* 预测分析表 */
void print() {/*输出分析栈和剩余栈 */
for(int i = 0; i <= top + 1; ++i) /*输出分析栈 */
cout << analyeStack[i];
cout << "\t\t";
for(int i = 0; i < ridx; ++i) /*输出对齐符*/
cout << ' ';
for(int i = ridx; i <= len; ++i) /*输出剩余串*/
cout << restStack[i];
cout << "\t\t\t";
}
// 读文件
vector<string> readFile(string fileName) {
vector<string> res;
try {
ifstream fin;
fin.open(fileName);
string temp;
while (getline(fin, temp))
res.push_back(temp);
return res;
} catch(const exception& e) {
cerr << e.what() << '\n';
return res;
}
}
bool isTerminator(char c) { // 判断是否是终结符
return v1.find(c) != string::npos;
}
void init(string exp) {
top = ridx = 0;
len = exp.length(); /*分析串长度*/
for(int i = 0; i < len; ++i)
restStack[i] = exp[i];
}
void analyze(string exp) { // 分析一个文法
init(exp);
int k = 0;
analyeStack[top] = '#';
analyeStack[++top] = 'E'; /*'#','E'进栈*/
cout << "步骤\t\t分析栈 \t\t剩余字符 \t\t所用产生式 " << endl;
while(true) {
char ch = restStack[ridx];
char x = analyeStack[top--]; /*x为当前栈顶字符*/
cout << ++k << "\t\t";
if(x == '#') {
cout << "分析成功！AC！\n" << endl; /*接受 */
return;
}
if(isTerminator(x)) {
if (x == ch) { // 匹配上了
print();
cout << ch << "匹配" << endl;
ch = restStack[++ridx]; /*下一个输入字符*/
} else { /*出错处理*/
print();
cout << "分析出错，错误终结符为" << ch << endl; /*输出出错终结符*/
return;
}
} else { /*非终结符处理*/
int m, n; // 非终结符下标， 终结符下标
v2.find(x) != string::npos ? m = v2.find(x) : -1; // m为-1则说明找不到该非终结符，出错
v1.find(ch) != string::npos ? n = v1.find(ch) : -1; // n为-1则说明找不到该终结符，出错
if(m == -1 || n == -1) { /*出错处理*/
print();
cout << "分析出错，错误非终结符为" << x << endl; /*输出出错非终结符*/
return;
}
type nowType = C[m][n];/*用来接受C[m][n]*/
if(nowType.origin != 'N') {/*判断是否为空*/
print();
cout << nowType.origin << "->" << nowType.array << endl; /*输出产生式*/
for (int j = (nowType.length - 1); j >= 0; --j) /*产生式逆序入栈*/
analyeStack[++top] = nowType.array[j];
if (analyeStack[top] == '^') /*为空则不进栈*/
top--;
} else { /*出错处理*/
print();
cout << "分析出错，错误非终结符为" << x << endl; /*输出出错非终结符*/
return;
}
}
}
}
int main() {
e.init('E', "TG"), t.init('T', "FS");
g.init('G', "+TG"), g1.init('G', "^");
s.init('S', "*FS"), s1.init('S', "^");
f.init('F', "(E)"), f1.init('F', "i"); /* 结构体变量 */
/*填充分析表*/
C[0][0] = C[0][3] = e;
C[1][1] = g;
C[1][4] = C[1][5] = g1;
C[2][0] = C[2][3] = t;
C[3][2] = s;
C[3][4] = C[3][5] = C[3][1] = s1;
C[4][0] = f1; C[4][3] = f;
cout << "LL（1）分析程序分析程序，编制人：xxx xxx 计科xxxx班" << endl;
cout << "提示:本程序只能对由'i','+','*','(',')'构成的以'#'结束的字符串进行分析，每行一个读入的字符串" << endl;
cout << "读取的文件名为：" << ExpFileName << endl;
vector<string> exps = readFile(ExpFileName);
int len = exps.size();
for(int i = 0; i < len; i++) {
string exp = exps[i];
cout << "------------------待分析字符串" << i+1 << "："<< exp << "--------------------" << endl;
bool flag = true;
for(int j = 0; j < exp.length(); j++) {
if(!isTerminator(exp[j])) {
cout << "第"<< i+1 << "行输入的字符串不合法，请重新输入" << endl;
flag = false;
break;
}
}
if(flag) {
cout << "字符串" << i+1 << "：" << exp << endl;
analyze(exp);
}
}
return 0;
}
