python实现DFA模拟程序(附java实现代码)

M=(K，∑，f，S，Z)

G[S]:   
S->aU|bV
U->bV|aQ
Q->aQ|bQ

 -*- coding: utf-8 -*- #
#@author: chlinlearn
#@createTime: 2019/4/13 14:12
#@fileName: DFA
class DFA():
    def __init__(self):
        #状态集
        self.listEdge = []
        #初态
        self.S = []
        #终态
        self.Z = []

    #判断是否是终态集
    def isZ(self,ch):
        for i in range(0,len(self.Z)) :
            if self.Z[0] == ch or self.Z[1] == ch:
                return True
            else:
                return False

    #输入
    def input(self):
        self.S = input("请输入开始符：")
        self.Z = input("请输入终态集(终集符组成的一个字符串)：")
        self.Z = self.Z.split(",")
        print("请输入正规文法以exit结尾：")
        print("example:S,aZ")
        while(True):
            list = []
            inStr = input()
            if inStr=='exit':
                break
            inStr = inStr.split(',')
            # 读取第一个状态集
            s = inStr[0]
            for i in range(0,len(inStr[1])):
                #ch,ns
                if len(inStr[1])==2:
                    c = inStr[1][0]
                    n = inStr[1][1]
                    list = [s,c,n]
                    self.listEdge.append(list)
                elif len(inStr[1])==1:
                    c = inStr[1][0]
                    list = [s, c, self.Z[0]]
                    self.listEdge.append(list)

    #转换函数
    def isNextState(self,s,ch):
        for i in range(0,len(self.listEdge)):
            if s == self.listEdge[i][0] and ch == self.listEdge[i][1]:
                return self.listEdge[i][2]
        return

    def judgeDFA(self):
        print("请输入要判断的字符串:")
        while(True):
            #获取字母表
            str = input()
            if '#' in str :
                print("程序已退出，欢迎下次使用!")
                return
            temp = self.S[0]
            for i in range(0,len(str)):
                if str[i] is 'a':
                    temp = self.isNextState(temp,'a')
                elif str[i] is 'b':
                    temp = self.isNextState(temp, 'b')
                else:
                    break
            if self.isZ(temp):
                print("此字符串“属于”该文法！")
            else:
                print("此字符串“不属于”该文法！")
            print("再次判断请输入字符串(退出程序输入#):")

if __name__ == '__main__':
    DFA = DFA()
    DFA.input()
    DFA.judgeDFA()

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

class edge {
	
    char PriorityState;
    char ch; 
    char NextState;
    edge(char p,char c, char n){
        PriorityState = p;
        ch = c;
        NextState = n;
    }
    @Override
    public String toString() {
        return "edge [PriorityState=" + PriorityState + ", ch=" + ch + ", NextState=" + NextState + "]";
    }
}
/**DFA的构造*/
public class DFA {
    static List<edge> listEdge = new ArrayList<edge>();//状态集
    //static HashMap<edge, Character> mapEdge = new HashMap<>();
    static String S;//初态集
    static String Z;//终态集
    //flag is here
    static boolean judeZ(char ch){       
        for(int j=0; j<Z.length(); j++){
            if(Z.charAt(j)==ch) return true;
        }
        return false;
    }
    static void input() {
        Scanner in = new Scanner(System.in);
        String instr = null;
        String subStr[] = null;
        System.out.println("请输入开始符：");
        S = in.next();
        System.out.println("请输入终态集(终集符组成的一个字符串)：");
        Z = in.next();
        System.out.println("请输入正规文法以end结尾(形式如下图)：");
        System.out.println("----------");
        System.out.println("|  S-aU  |");
        System.out.println("|  S-bV  |");
        System.out.println("|  U-bV  |");
        System.out.println("|  ....  |");
        System.out.println("|  end   |");
        System.out.println("----------");
        while(in.hasNext()){
            instr = in.next();
            if("end".equals(instr)) 
            	break;
            subStr = instr.split("-|\\|");//连字符
            System.out.println("subStr:"+subStr);
            String s = subStr[0];//读取一行f(转换函数)
            System.out.println(s);
            for(int i=1; i<subStr.length; i++){
                edge e = null;
                System.out.println(subStr[1]);
                if(subStr[i].length()==2){
                    char c = subStr[i].charAt(0);//字母表
                    char n = subStr[i].charAt(1);//状态集
                    listEdge.add(new edge(s.charAt(0),c,n));//f(S,a)=U
                }
                
                if(subStr[i].length()==1){
                    char c = subStr[i].charAt(0);
                    listEdge.add(new edge(s.charAt(0),c,Z.charAt(0)));
                }
            }
        }
    }
    
    static char judeNextState(char s,char ch){
        for(int i=0; i<listEdge.size(); i++){
            if(s==listEdge.get(i).PriorityState && ch==listEdge.get(i).ch){
                return listEdge.get(i).NextState;
            }
        }
        return '0';
    }
    
    static void judeDFA(){
        Scanner in = new Scanner(System.in);
        System.out.println("请输入要判断的字符串:");
        while(in.hasNext()){
            String str = in.next();
            if(str.equals("#")){
                System.out.println("程序已退出，欢迎下次使用!");
                return;
            }
            char temp = S.charAt(0);
            int i=0;
            //System.out.println(temp+" "+mapEdge.get(e));
            for(; i<str.length(); i++){
                //System.out.println("temp="+temp);
                if(str.charAt(i)=='a'){
                    temp = judeNextState(temp, 'a');
                }
                else if(str.charAt(i)=='b'){
                    temp = judeNextState(temp, 'b');
                }
                else break;
            }
            //flag is here
            if(i>=str.length() && judeZ(temp)) System.out.println("此字符串“属于”该文法！");
            else System.out.println("此字符串“不属于”该文法！");
            System.out.println("再次判断请输入字符串(退出程序输入#):");
        }
        
    }
    
    /*main*/
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        DFA.input();
        DFA.judeDFA();
    }
}