First word-count FSM Implement

word-count FSM Implement.cpp

#include <stdio.h>
#include <map>
#include <utility>
#include <functional>

enum STATE {
    IN,
    OUT,
};

std::map<STATE, std::function<STATE(char, int *)>> fsm = {
    {
        OUT, [](char c, int *count){
            if (c == ' ' || c == '\t')
                return OUT;
            else {
                *count = *count + 1;
                return IN;
            }
        }},
    {
        IN, [](char c, int *count){
            if (c != ' ' && c != '\t') {
                return IN;
            } else {
                return OUT;
            }
        }
    }

};


std::map<std::pair<STATE, STATE>, std::function<STATE(int *)>> fsm2 = {
    {
        {OUT, OUT}, [](int *count){
            return OUT;
        }
    },
    {
        {OUT, IN}, [](int *count){
            *count = *count + 1;
            return IN;
        }
    },
    {
        {IN, OUT}, [](int *count){
            return OUT;
        }
    },
    {
        {IN, IN}, [](int *count){
            return IN;
        }
    },
};

std::map<STATE, std::function<void(void)>> fsm2_enter = {
    {
        OUT, [](){
            printf("enter OUT\n");
        }
    },
    {
        IN, [](){
            printf("enter IN\n");
        }
    },

};

std::map<STATE, std::function<void(void)>> fsm2_exit = {
    {
        OUT, [](){
            printf("exit OUT\n");
        }
    },
    {
        IN, [](){
            printf("exit IN\n");
        }
    },

};

std::map<std::pair<STATE, STATE>, std::function<void(int *)>> fsm2_2 = {
    {
        {OUT, IN}, [](int *count){
            fsm2_exit[OUT]();
            *count = *count + 1;
            fsm2_enter[IN]();
        }
    },
    {
        {OUT, OUT}, [](int *count){
            fsm2_exit[OUT]();
            fsm2_enter[OUT]();
        }
    },
    {
        {IN, IN}, [](int *count){
            fsm2_exit[IN]();
            fsm2_enter[IN]();
        }
    },

    {
        {IN, OUT}, [](int *count){
            fsm2_exit[IN]();
            fsm2_enter[OUT]();
        }
    },
};





std::map<STATE, std::function<std::pair<STATE,STATE>(char)>> fsm2_judge = {
    {
        OUT, [](char c){
            return (c == ' ' || c == '\t') ? std::make_pair(OUT, OUT) : std::make_pair(OUT, IN);
        }
    },
    {
        IN, [](char c){
            return (c != ' ' && c != '\t') ? std::make_pair(IN, IN) : std::make_pair(IN, OUT);
        }

    },
};



int main()
{
    char c;
    int count = 0; // word count
    STATE state = OUT;
    while ( scanf("%c", &c) != EOF && c != '\n' ) {
        // 1. first implement
        // state = fsm[state](c, &count);

        // 2. second implement
        /*
         switch (state) {
         case OUT:
         {
         if (c == ' ' || c == '\t')
         {
         state = fsm2[{OUT,OUT}](&count);
         }
         else
         {
         state = fsm2[{OUT,IN}](&count);
         }

         }
         break;
         case IN:
         if (c != ' ' && c != '\t') {
         state = fsm2[{IN,IN}](&count);
         }
         else {
         state = fsm2[{IN,OUT}](&count);
         }
         break;
         }
         */

        // 3. third implement based on 2
        //state = fsm2[fsm2_judge[state](c)](&count);

        // 4. 4th implement based on 3
        auto state_transfrom = fsm2_judge[state](c);
        if (fsm2_2.find(state_transfrom) != fsm2_2.end()) {
            fsm2_2[state_transfrom](&count);
        }
        state = state_transfrom.second;
    }
    printf("word count: %d\n",count);
    return 0;
}

TODO: rewrite it in OOP way