LL(1)语法分析程序

import java.io.IOException;
import java.util.Stack;

/**
 * 语法分析程序
 * @author 霍淇滨
 *
 */
public class Analysis {
	private Stack<Character> ans;		//分析栈
	private Stack<Character> aim;		//余留字符串栈
	private String[][] table;		//分析表
	private int count = 1;
	/**
	 * 构造函数，初始化栈和表
	 * @param str
	 */
	public Analysis(String str) {
		ans = new Stack<Character>();
		aim = new Stack<Character>();
		table = new String[5][6];		
		System.out.println(str);
		
		aim.push('#');
		for(int i = str.length()-1;i>=0;i--)		//初始化余留字符串栈
			aim.push(str.charAt(i));
		ans.push('#');		//初始化分析栈
		
		construct();		//构建分析表
	}
	
	/**
	 * 构建分析表
	 */
	private void construct() {
		table[0][0] = "TS";table[0][1] = "error";table[0][2] = "error";table[0][3] = "TS";table[0][4] = "error";table[0][5] = "error";
		table[1][0] = "error";table[1][1] = "+TS";table[1][2] = "error";table[1][3] = "error";table[1][4] = "0";table[1][5] = "0";
		table[2][0] = "FZ";table[2][1] = "error";table[2][2] = "error";table[2][3] = "FZ";table[2][4] = "error";table[2][5] = "error";
		table[3][0] = "error";table[3][1] = "0";table[3][2] = "*FZ";table[3][3] = "error";table[3][4] = "0";table[3][5] = "0";
		table[4][0] = "i";table[4][1] = "error";table[4][2] = "error";table[4][3] = "(E)";table[4][4] = "error";table[4][5] = "error";
	}
	
	/**
	 * 从分析表中获取字符串
	 * @param A
	 * @param a
	 * @return
	 */
	public String getString(char A,char a) {
		int i=0,j=0;
		switch(A) {		//匹配非终结符
		case 'E':	i = 0;break;
		case 'S':	i = 1;break;
		case 'T':	i = 2;break;
		case 'Z':	i = 3;break;
		case 'F':	i = 4;break;
		}
		switch(a) {		//匹配终结符
		case 'i':	j = 0;break;
		case '+':	j = 1;break;
		case '*':	j = 2;break;
		case '(':	j = 3;break;
		case ')':	j = 4;break;
		case '#':	j = 5;break;
		}
		return table[i][j];
	}
	
	/**
	 * 语法分析方法
	 */
	public void analyzer() {
		char N,n;
		ans.push('E');
		PrintHead();
		n = aim.pop();
		aim.push(n);
		Print('E',n);
		
		while(!ans.isEmpty()) {		//终结条件：分析栈为空
			char A = ans.pop();		//分析栈出栈
			char a = aim.pop();		//余留栈出栈
			
			if(A == a) {
				Print('$','$');
				continue;	//相同，双方都需要出栈，继续循环
			}
			aim.push(a);	//否则余留字符重新入栈
			String st = getString(A,a);		//查询分析表
			if(st.equals("error")) {		//为空，算法结束，匹配不成功
				Print(A,a);
				break;
			}
			else if(st.equals("0")) {
				Print(A,a);
				continue;		//0表示空，不需要入分析栈直接进行下一次循环
			}
			else {
				for(int i = st.length()-1;i>=0;i--) {		//逆序入栈
					ans.push(st.charAt(i));
				}
				Print(A,a);
			}
		}
		if(aim.isEmpty() && ans.isEmpty()) 	System.out.println("success");
		else System.out.println("failture");
	}
	
	/**
	 * 打印栈
	 * @param stack
	 */
	public void printStack(Stack<Character> stack) {
		for(Character s : stack)
			System.out.print(s);
		System.out.print("\t");
	}
	/**
	 * 打印分析过程
	 * @param A
	 * @param a
	 */
	public void Print(char A, char a) {
		if(ans.isEmpty()) return;
		System.out.print("步骤" + count++ +"\t");
		printStack(ans);
		printStack(aim);
		if(count==2) {
			System.out.println();
			return;
		}
		if(A == '$' && a == '$') {
			System.out.println();
			return;
		}
		else {
			if(A == '#') System.out.println("success");
			else {
				System.out.print("" + A + "->" + getString(A,a));
				System.out.println();
			}
		}
		
	}
	/**
	 * 打印头部
	 */
	public void PrintHead() {
		System.out.println("步骤\t"+"分析栈\t"+"余留栈\t"+"上个步骤所用产生式");
	}
	/**
	 * 测试方法
	 * @param args
	 * @throws IOException 
	 */
	public static void main(String[] args) throws IOException {
		Analyzer ans = new Analyzer("./src/success.txt");//成功样例
		//Analyzer ans = new Analyzer("./src/failture.txt");//失败样例
		ans.readFile();	
		ans.analyse();	
		String str = ans.reStr();

		Analysis run = new Analysis(str);
		run.analyzer();
	}
}