[编译原理]SLR分析器

题目：

考虑简单算术表达式文法G:

E→E + T | T

T→T * F | F

F→(E) | id

试设计SLR(1)或者LR(1)分析程序，以输入的 (a+b)*c+(d+e) 符号串进行语法分析。

解：

解题步骤：求增广文法->求LR(0)自动机->求Follow集->求SLR分析表

增广文法：

LR(0)自动机：

Follow集：

SLR分析表：

        

#include<bits/stdc++.h>
using namespace std;


string input_str;
string input_stack[1000];
int input_top = -1;//输入栈
string sysbol_stack[1000];
int sysbol_top = -1;//符号栈
int num[100];//状态栈
int state_top = -1;
map<int, map<string, pair<string, int >>>Action;
map<string, int> hasp_map;
map<int,map<string,int> >Goto;
map<string, int> len_hash;//映射长度

pair<string,string> Equation[30];//产生式
int Equation_tot=-1;



void print()
{
	//打印输出结果
	//打印状态栈
	//cout << "状态栈->符号栈->剩余输入" << endl;
	for (int i = 0; i <= 20 || i <= state_top; i++)
	{
		if (i <= state_top)
			cout << num[i] << " ";
		else
			cout << " ";
	}
	//打印符号栈
	for (int i = 0; i <= 30 || i <= sysbol_top; i++)
	{
		if (i <= sysbol_top)
			cout << sysbol_stack[i] << " ";
		else
			cout << " ";
	}
	//打印剩余输入
	for (int i = input_top; i>=0; i--)
	{
		if (i>=0)
			cout << input_stack[i] << " ";
		else
			cout << " ";
	}
	cout << endl;
}

bool parse()
{
	while (input_top != -1)
	{
		print();
		//cout << "第一个：" << Action[num[state_top]][input_stack[input_top]].first << endl;
		if (Action[num[state_top]][input_stack[input_top]].first == "s")
		{
			//移入操作
			int state = Action[num[state_top]][input_stack[input_top]].second;
			num[++state_top] = state;//移入状态
			sysbol_stack[++sysbol_top] = input_stack[input_top];//移入符号
			input_top--;//输入栈出栈
		}
		else if (Action[num[state_top]][input_stack[input_top]].first == "r")
		{
			//归约操作
			int Equation_num=Action[num[state_top]][input_stack[input_top]].second;//归约的式子
			//cout << "归约的式子" << Equation[Equation_num].first <<"->" << Equation[Equation_num].second << endl;
			//cout << "长度：" << Equation[Equation_num].second.size() << endl;
			//int len = Equation[Equation_num].second.size();
			int temp_len = len_hash[Equation[Equation_num].second];
			sysbol_top -= temp_len;//符号栈出栈
			sysbol_stack[++sysbol_top] = Equation[Equation_num].first;//放入归约后的符号

			state_top-= temp_len;//状态栈出栈
			int temp = state_top;
			num[++state_top] = Goto[num[temp]][sysbol_stack[sysbol_top]];//放入归约后的数字
		}
		else if (Action[num[state_top]][input_stack[input_top]].first == "acc")
		{
			return 1;
		}
		else
		{
			return 0;
		}
	}
	return 0;
}
void init()
{
	//初始化输入栈
	input_stack[++input_top] = "$";
	reverse(input_str.begin(), input_str.end());
	for (int i = 0; i < input_str.size(); i++)
	{
		if (input_str[i] >= 'a' && input_str[i] <= 'z')
			input_stack[++input_top] = "id";
		else
			input_stack[++input_top].push_back(input_str[i]);
	}
	//初始化状态栈
	num[++state_top] = 0;//初始化为0
	//初始化符号栈
	sysbol_stack[++sysbol_top] = "$";//初始化栈顶
	//初始化符号映射关系
	//初始化Goto
	Goto[0]["E"] = 1;
	Goto[0]["T"] = 2;
	Goto[0]["F"] = 3;

	Goto[4]["T"] = 2;
	Goto[4]["F"] = 3; 
	Goto[4]["E"] = 8;

	Goto[6]["F"] = 3;
	Goto[6]["T"] = 9;
	Goto[7]["F"] = 10;
	//初始化构造表
	Action[0]["id"].first = "s";	Action[0]["id"].second = 5;
	Action[0]["("].first = "s";	Action[0]["("].second = 4;

	Action[1]["+"].first = "s";	Action[1]["+"].second = 6;
	Action[1]["$"].first = "acc";

	Action[2]["+"].first = "r";	Action[2]["+"].second =2;
	Action[2][")"].first = "r";	Action[2][")"].second =2;
	Action[2]["$"].first = "r";	Action[2]["$"].second =2;
	Action[2]["*"].first = "s";	Action[2]["*"].second =7;

	Action[3]["+"].first = "r";	Action[3]["+"].second = 4;
	Action[3][")"].first = "r";	Action[3][")"].second = 4;
	Action[3]["$"].first = "r";	Action[3]["$"].second = 4;
	Action[3]["*"].first = "r";	Action[3]["*"].second = 4;

	Action[4]["id"].first = "s";	Action[4]["id"].second = 5;
	Action[4]["("].first = "s";	Action[4]["("].second = 4;
	
	Action[5]["+"].first = "r";	Action[5]["+"].second = 6;
	Action[5][")"].first = "r";	Action[5][")"].second = 6;
	Action[5]["$"].first = "r";	Action[5]["$"].second = 6;
	Action[5]["*"].first = "r";	Action[5]["*"].second = 6;

	Action[6]["id"].first = "s";	Action[6]["id"].second = 5;
	Action[6]["("].first = "s";	Action[6]["("].second = 4;

	Action[7]["id"].first = "s";	Action[7]["id"].second = 5;
	Action[7]["("].first = "s";	Action[7]["("].second = 4;


	Action[8]["+"].first = "s";	Action[8]["+"].second = 6;
	Action[8][")"].first = "s";	Action[8][")"].second = 11;

	Action[9]["+"].first = "r";	Action[9]["+"].second = 1;
	Action[9][")"].first = "r";	Action[9][")"].second = 1;
	Action[9]["$"].first = "r";	Action[9]["$"].second = 1;
	Action[9]["*"].first = "s";	Action[9]["*"].second = 7;

	Action[10]["+"].first = "r";	Action[10]["+"].second = 3;
	Action[10][")"].first = "r";	Action[10][")"].second = 3;
	Action[10]["$"].first = "r";	Action[10]["$"].second = 3;
	Action[10]["*"].first = "r";	Action[10]["*"].second = 3;

	Action[11]["+"].first = "r";	Action[11]["+"].second = 5;
	Action[11][")"].first = "r";	Action[11][")"].second = 5;
	Action[11]["$"].first = "r";	Action[11]["$"].second = 5;
	Action[11]["*"].first = "r";	Action[11]["*"].second = 5;

	//初始化产生式
	Equation[++Equation_tot].first = "S", Equation[Equation_tot].second = "E";
	Equation[++Equation_tot].first = "E", Equation[Equation_tot].second = "E+T";
	Equation[++Equation_tot].first = "E", Equation[Equation_tot].second = "T";
	Equation[++Equation_tot].first = "T", Equation[Equation_tot].second = "T*F";
	Equation[++Equation_tot].first = "T", Equation[Equation_tot].second = "F";
	Equation[++Equation_tot].first = "F", Equation[Equation_tot].second = "(E)";
	Equation[++Equation_tot].first = "F", Equation[Equation_tot].second = "id";
	//映射长度
	len_hash["E+T"] = 3;
	len_hash["(E)"] = 3;
	len_hash["T*F"] = 3;
	len_hash["id"] = 1;
	len_hash["E"] = len_hash["T"]= len_hash["F"]=1;

}

int main()
{
	cin >> input_str;//输入串
	init();
	//初始化分析表
	bool ans=parse();
	if (ans)
	{
		cout << "accept!" << endl;
	}
	else
	{
		cout << "wrong!" << endl;
	}
	return 0;
}