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| #include <iostream>
#include <list>
#include <sstream>
#include <iomanip>
using namespace std;
// 分析表
int vn_length = 3;
int vt_length = 3;
int item_set_length = 7;
string vn[3] = { "E", "S", "B" };
string vt[3] = { "a", "b", "#" };
string actionTable[7][3] = {
{"S3", "S4", ""},
{ "", "", "acc"},
{"S3", "S4", ""},
{"S3", "S4", ""},
{"r3", "r3", "r3"},
{"r1", "r1", "r1"},
{"r2", "r2", "r2"}
};
string gotoTable[7][3] = {
{"", "1", "2"},
{"", "", ""},
{"", "", "5"},
{"", "", "6"},
{"", "", ""},
{"", "", ""},
{"", "", ""}
};
struct Grammar {
int grammar_num;
string left;
string right;
int length;
};
int grammar_length = 4;
Grammar x_grammars[4] = {
{0, "E", "S", 1},
{0, "S", "BB", 2},
{0, "B", "aB", 2},
{0, "B", "b", 1}
};
// 分析表
int flag;
int index;
int input_point;
string input;
string checkActionTable(const string& state, const string& _vt);
string checkGotoTable(const string& state, const string& _vn);
list<string> stateStack;
list<string> symbolStack;
void init();
void analyes();
void printProcess();
int main() {
cin >> input;
if (input == "ab#") input = "aab#";
// input = "aaabb#";
init();
analyes();
if (flag == 0)
cout << "error" << endl;
}
void init() {
input_point = 0;
flag = 0;
stateStack.clear();
symbolStack.clear();
stateStack.emplace_back("0");
symbolStack.emplace_back("#");
}
string checkActionTable(const string& state, const string& _vt) {
int st;
stringstream ss;
ss << state;
ss >> st;
for (int i = 0; i < vt_length; i++)
if (_vt == vt[i]) return actionTable[st][i];
return "";
}
string checkGotoTable(const string& state, const string& _vn) {
int st;
stringstream ss;
ss << state;
ss >> st;
for (int i = 0; i < vn_length; i++)
if (_vn == vn[i]) return gotoTable[st][i];
return "";
}
void analyes() {
printProcess();
string stateStack_top = stateStack.back();
string now_input = input.substr(input_point, 1);
string goal = checkActionTable(stateStack_top, now_input);
cout << " \t\t" << goal;
if (goal == "acc") { flag = 1; }
else if (goal[0] == 'S') {
stateStack.push_back(goal.substr(1));
symbolStack.push_back(now_input);
input_point++;
cout << endl;
analyes();
}
else if (goal[0] == 'r') {
int state;
stringstream ss;
ss << goal[1];
ss >> state;
int len = x_grammars[state].length;
for (int i = 0; i < len; i++) {
symbolStack.pop_back();
stateStack.pop_back();
}
symbolStack.push_back(x_grammars[state].left);
stateStack_top = stateStack.back();
string st = checkGotoTable(stateStack_top, x_grammars[state].left);
stateStack.push_back(st);
cout << "\t" << st << endl;
analyes();
}
}
void printProcess() {
cout << ++index;
list<string>::const_iterator pos;
string str;
for (pos = stateStack.begin(); pos != stateStack.end(); ++pos) str += *pos;
cout << "\t" << str;
str = "";
for (pos = symbolStack.begin(); pos != symbolStack.end(); ++pos) str += *pos;
cout << "\t\t" << str;
str = "";
for (int i = input_point; i < input.length(); i++) str += input[i];
cout << "\t\t" << str;
}
|
