编译原理： LR分析器（Java）

基本要求

文法：

输入：LR分析表

输出：栈内容和输入内容的变化序列

代码

import java.util.Scanner;
import java.util.Stack;

public class LR {
	
	private static String Sub = null;          //输入串的待处理部分
	private static boolean acc = false;        // 是否已处理完输入串
	private static boolean bResult = false;    // 是否出错
	// 转移
    private static int[][] Goto = new int[][] { { 1, 2, 3 }, { 0, 0, 0 }, { 0, 0, 0 }, 
    	                                        { 0, 0, 0 }, { 8, 2, 3 }, { 0, 0, 0 }, 
    	                                        { 0, 9, 3 }, { 0, 0, 10 }, { 0, 0, 0 }, 
    	                                        { 0, 0, 0 }, { 0, 0, 0 }, { 0, 0, 0 } }; 
    // 输入要分析的字符串
    private String input() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入以#结尾的字符串：");
        String s = scanner.nextLine();
        scanner.close();
        return s;
    }
    
    public static void tran(int state, char nonterminal,Stack<String> stack) {
		int i = -1;
		if (nonterminal == 'E')
			i = 0;
		if (nonterminal == 'T')
			i = 1;
		if (nonterminal == 'F')
			i = 2;
		stack.push(nonterminal + "");    
		stack.push(Goto[state][i] + "");  
 
	}
    
    private void drive(String token) {
        Stack<String> anStack = new Stack<>();
        Sub = token;
		anStack.push(String.valueOf(0));
		while (!bResult && acc == false) {
			switch (anStack.peek().charAt(0)) {
			case '0':
				System.out.printf("%-52s%-50s%-50s\n"," 栈"," 输入","动作");
		        System.out.printf("%-30s%-30s",anStack.toString(),token);
				if (Sub.substring(0, 2).equals("id")) {
					anStack.push("id");
					anStack.push("" + 5);
					Sub = Sub.substring(2, Sub.length());
					token = token.substring(2);
					System.out.println("移进");
				    System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else if (Sub.substring(0, 1).equals("(")) {
					anStack.push("(");
					anStack.push("" + 4);
					Sub = Sub.substring(1, Sub.length());
					token = token.substring(1);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);	
				} else {
					System.out.println("error");
				}
				break;
			case '1':
				if ("1".equals(anStack.peek())) {
					if (Sub.substring(0, 1).equals("+")) {
						anStack.push("+");
						anStack.push("" + 6);
						Sub = Sub.substring(1, Sub.length());
						token = token.substring(1);
						System.out.println("移进");
						System.out.printf("%-30s%-30s",anStack.toString(),token);
					} else if (Sub.substring(0, 1).equals("#")) {
						acc = true;
						System.out.println("接受");
						//System.out.printf("%-30s%-30s",anStack.toString(),token);
					} else {
						System.out.println("error");
				    }
					break;
				} else if (anStack.peek().charAt(1) == '0') {
					if (Sub.substring(0, 1).equals("+")||Sub.substring(0, 1).equals(")")
						||Sub.substring(0, 1).equals("#")||Sub.substring(0, 1).equals("*")) {
						for(int i=0;i<6;i++)
							anStack.pop();
						tran((int) anStack.peek().charAt(0) - (int) '0', 'T', anStack);
						System.out.println("按T->T*F归约");
						System.out.printf("%-30s%-30s",anStack.toString(),token);
						break;
					}
					else {
					    for(int i=0;i<=6;i++)
						    anStack.pop();
					    tran((int) anStack.peek().charAt(0) - (int) '0', 'F', anStack);
					    System.out.println("按F->(E)归约");
					    System.out.printf("%-30s%-30s",anStack.toString(),token); 
					}
				break;
			}
			case '2':
				if (Sub.substring(0, 1).equals("*")) {
					anStack.push("*");
				    anStack.push("" + 7);
					Sub = Sub.substring(1, Sub.length());
					token = token.substring(1);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else if (Sub.substring(0, 1).equals("+")||Sub.substring(0, 1).equals(")")
						   ||Sub.substring(0, 1).equals("#")) {
					anStack.pop();
					anStack.pop();
					tran((int) anStack.peek().charAt(0) - (int) '0', 'E', anStack);
					System.out.println("按E->T归约");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else {
					System.out.println("error");
			      }
				break;
			case '3':
				if(Sub.substring(0, 1).equals("+")||Sub.substring(0, 1).equals("*")
				   ||Sub.substring(0, 1).equals(")")||Sub.substring(0, 1).equals("#")) {
					anStack.pop();
					anStack.pop();
				    tran((int) anStack.peek().charAt(0) - (int) '0', 'T', anStack);
				    System.out.println("按T->F归约");
				    System.out.printf("%-30s%-30s",anStack.toString(),token);
				    break;
				}
			case '4':
				if (Sub.substring(0, 2).equals("id")) {
					anStack.push("id");
					anStack.push("" + 5);
					Sub = Sub.substring(2, Sub.length());
					token = token.substring(2);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else if (Sub.substring(0, 1).equals("(")) {
					anStack.push("(");
					anStack.push("" + 4);
					Sub = Sub.substring(1, Sub.length());
					token = token.substring(1);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else
					System.out.println("error");
				break;
			case '5':
				if(Sub.substring(0, 1).equals("+")||Sub.substring(0, 1).equals("*")
				   ||Sub.substring(0, 1).equals(")")||Sub.substring(0, 1).equals("#")) {
					anStack.pop();
					anStack.pop();
					tran((int) anStack.peek().charAt(0) - (int) '0', 'F', anStack);
					System.out.println("按F->id归约");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				}
				break;
			case '6':
				if (Sub.substring(0, 2).equals("id")) {
					anStack.push("id");
					anStack.push("" + 5);
					Sub = Sub.substring(2, Sub.length());
					token = token.substring(2);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else if (Sub.substring(0, 1).equals("(")) {
					anStack.push("(");
					anStack.push("" + 4);
					Sub = Sub.substring(1, Sub.length());
					token = token.substring(1);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else
					System.out.println("error");
				break;
			case '7':
				if (Sub.substring(0, 2).equals("id")) {
					anStack.push("id");
					anStack.push("" + 5);
					Sub = Sub.substring(2, Sub.length());
					token = token.substring(2);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else if (Sub.substring(0, 1).equals("(")) {
					anStack.push("(");
					anStack.push("" + 4);
					Sub = Sub.substring(1, Sub.length());
					token = token.substring(1);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else
					System.out.println("error");
				break;
			case '8':
				if (Sub.substring(0, 1).equals("+")) {
					anStack.push("+");
					anStack.push("" + 6);
					Sub = Sub.substring(1, Sub.length());
					token = token.substring(1);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else if (Sub.substring(0, 1).equals(")")) {
					anStack.push(")");
					anStack.push("" + 11);
					Sub = Sub.substring(1, Sub.length());
					token = token.substring(1);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else
					System.out.println("error");
				break;
			case '9':
				if (Sub.substring(0, 1).equals("*")) {
					anStack.push("*");
					anStack.push("" + 7);
					Sub = Sub.substring(1, Sub.length());
					token = token.substring(1);
					System.out.println("移进");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				} else if(Sub.substring(0, 1).equals("+")||Sub.substring(0, 1).equals(")")||Sub.substring(0, 1).equals("#")){
					for(int i=0;i<=5;i++)
						anStack.pop();
					tran((int) anStack.peek().charAt(0) - (int) '0', 'E', anStack);
					System.out.println("按E->E+T归约");
					System.out.printf("%-30s%-30s",anStack.toString(),token);
				}
				break;
			}
			
		}
		if (acc)
		    System.out.println("匹配成功");
}

    public static void main(String[] args) {
        LR p = new LR();
        String token = p.input();
        p.drive(token);
    }
}

运行结果

本文地址：https://blog.csdn.net/weixin_45596016/article/details/110846339