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 wf = new ArrayList();
private HashMap> follow = new HashMap>();
private String[][] table = new String[12][9];
private Stack stateStack = new Stack();
private Stack charStack = new Stack();
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 Sfl = new ArrayList();
List Efl = new ArrayList();
List Tfl = new ArrayList();
List Ffl = new ArrayList();
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 stateStr = new ArrayList();
List charStr = new ArrayList();
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
