SLR(1)语法分析(JAVA实现)

要求

代码

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Stack;

public class SLRFX {

    private List<String> wf = new ArrayList<String>();
    private HashMap<String,List<String>> follow = new HashMap<String, List<String>>();
    private String[][] table = new String[12][9];
    private Stack<String> stateStack = new Stack<String>();
    private Stack<String> charStack = new Stack<String>();

    public SLRFX(){
        init();
    }

    /**
     * 初始化
     */
    private void  init(){
        wf.add("S->E");
        wf.add("E->E+T");
        wf.add("E->T");
        wf.add("T->T*F");
        wf.add("T->F");
        wf.add("F->(E)");
        wf.add("F->i");
        List<String> Sfl = new ArrayList<String>();
        List<String> Efl = new ArrayList<String>();
        List<String> Tfl = new ArrayList<String>();
        List<String> Ffl = new ArrayList<String>();
        Sfl.add("#");
        Efl.add("#");
        Efl.add(")");
        Efl.add("+");
        Tfl.add("#");
        Tfl.add(")");
        Tfl.add("+");
        Tfl.add("*");
        Ffl.addAll(Tfl);
        follow.put("S",Sfl);
        follow.put("E",Efl);
        follow.put("T",Tfl);
        follow.put("F",Ffl);
        for (int i = 0; i < 12; i++) {
            for (int j = 0; j < 9; j++) {
                table[i][j] = "";
            }
        }
        table[0][0] = "s5";
        table[0][3] = "s4";
        table[0][6] = "1";
        table[0][7] = "2";
        table[0][8] = "3";
        table[1][1] = "s6";
        table[1][5] = "acc";
        table[2][1] = "r2";
        table[2][2] = "s7";
        table[2][4] = "r2";
        table[2][5] = "r2";
        table[3][1] = "r4";
        table[3][2] = "r4";
        table[3][4] = "r4";
        table[3][5] = "r4";
        table[4][0] = "s5";
        table[4][3] = "s4";
        table[4][6] = "8";
        table[4][7] = "2";
        table[4][8] = "3";
        table[5][1] = "r6";
        table[5][2] = "r6";
        table[5][4] = "r6";
        table[5][5] = "r6";
        table[6][0] = "s5";
        table[6][3] = "s4";
        table[6][7] = "9";
        table[6][8] = "3";
        table[7][0] = "s5";
        table[7][3] = "s4";
        table[7][8] = "10";
        table[8][1] = "s6";
        table[8][4] = "s4";
        table[9][1] = "r1";
        table[9][2] = "s7";
        table[9][4] = "r1";
        table[9][5] = "r1";
        table[10][1] = "r3";
        table[10][2] = "r3";
        table[10][4] = "r3";
        table[10][5] = "r3";
        table[11][1] = "r5";
        table[11][2] = "r5";
        table[11][4] = "r5";
        table[11][5] = "r5";
    }

    /**
     * 展示文法的信息
     */
    private void showTips(){
        System.out.println("输入的文法:");
        for (String s : wf) {
            System.out.println(s);
        }
        System.out.println("VT:+\t*\t(\r)\ti\t#");
        System.out.println("VN:E\tT\tF");
        System.out.println("\ti\t+\t*\t(\t)\t#\tE\tT\tF");
        for (int i = 0; i < 12; i++) {
            System.out.print(i);
            for (int j = 0; j < 9; j++) {
                System.out.print("\t" + table[i][j]);
            }
            System.out.println();
        }
    }

    /**
     * 删除字符串的第一个字符
     * @param str
     * @return
     */
    private String deleteFirstChar(String str){
        String[] strings = str.split("||");
        String newStr = "";
        for (int i = 1; i < strings.length; i++) {
            newStr += strings[i];
        }
        return newStr;
    }

    /**
     * 分析过程
     * @param jz
     */
    private void fx(String jz){
        List<String> stateStr = new ArrayList<String>();
        List<String> charStr = new ArrayList<String>();
        stateStack.push("0");
        stateStr.add("0");
        charStack.push("#");
        charStr.add("#");
        String sr = jz;
        boolean isok = false;
        int bz = 1;
        System.out.println("步骤\t\t状态栈\t\t符号栈\t\t输入串\t\tACTION\t\tGOTO\t\t动作");
        while (!isok){
            int topState = Integer.valueOf(stateStack.peek()).intValue();
            char nowChar = sr.charAt(0);
            String what = table[topState][getIndex(nowChar)];
            if (what.startsWith("s")){
                //移进
                String[] split = what.split("||");
                stateStack.push(split[1]);
                stateStr.add(split[1]);
                charStack.push(nowChar + "");
                charStr.add(nowChar + "");
                System.out.println(bz + "\t\t" + stateStr.toString() + "\t\t" + charStr  + "\t\t" + sr +
                        "\t\t" + what + "\t\t\t\t" + "0" + "\t\t移进");
                //输入串要减少
                sr = deleteFirstChar(sr);
            }else if (what.startsWith("r")){
                //规约
                String[] split = what.split("||");
                String[] css = wf.get(Integer.valueOf(split[1])).split("->");
                String VT = css[0];
                int popNum = css[1].length();
                //出栈
                for (int i = 0; i < popNum; i++) {
                    stateStack.pop();
                    stateStr.remove(stateStr.size()-1);
                    charStack.pop();
                    charStr.remove(charStr.size()-1);
                }
                int newTopState = Integer.valueOf(stateStack.peek()).intValue();
                String newState = table[newTopState][getIndex(VT.charAt(0))];
                stateStack.push(newState);
                stateStr.add(newState);
                charStack.push(VT);
                charStr.add(VT);
                System.out.println(bz + "\t\t" + stateStr.toString() + "\t\t" + charStr.toString() + "\t\t" +sr +
                        "\t\t" + what + "\t\t\t\t" + newState + "\t\t规约");
            }else if (what.equals("acc")){
                isok = true;
                System.out.println(bz + "\t\t" + stateStr.toString() + "\t\t" + charStr.toString() + "\t\t" +sr +
                        "\t\t" + "acc" + "\t\t\t\t" + "0" + "\t\t接受");
            }else {
                System.err.println("分析错误!输入的句子不符合语法!");
                System.exit(-1);
            }
            bz++;
        }
        System.out.println("分析完成!");
    }

    private int getIndex(char t){
        switch (t){
            case 'i':return 0;
            case '+':return 1;
            case '*':return 2;
            case '(':return 3;
            case ')':return 4;
            case '#':return 5;
            case 'E':return 6;
            case 'T':return 7;
            case 'F':return 8;
        }
        return -1;
    }

    public void run(String jz){
        showTips();
        fx(jz);
    }

}

测试代码：

public class TestSLR {

    public static void main(String[] args) {
        SLRFX slrfx = new SLRFX();
        slrfx.run("i+i*i#");
    }

}

结果