word-count FSM in simple way

word-count FSM in simple way.cpp

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

enum STATE
{
    IN,
    OUT,
};

enum EVENT
{
    WhiteSpace,
    Char,
};

enum TRANSITION
{
    OUT_IN,
    Nope,
};


//[WhiteSpace][IN] = OUT;
//[WhiteSpace][OUT] = OUT;
//[Char][IN] = IN;
//[Char][OUT] = IN;
STATE StateEvents[2][2] = {
    OUT,
    OUT,
    IN,
    IN,
};


std::map<std::pair<STATE, STATE>, TRANSITION> StateTrans = {
    {{OUT, OUT}, Nope},
    {{OUT, IN}, OUT_IN},
    {{IN, OUT}, Nope},
    {{IN, IN}, Nope},
};


int main()
{
    char c;
    int count = 0; // word count
    STATE state = OUT;
    while (scanf("%c", &c) != EOF && c != '\n') {
        EVENT event;
        // event judge
        if (c == ' ' || c == '\t') {
            event = WhiteSpace;
        } else {
            event = Char;
        }
        STATE newState = StateEvents[event][state];
        auto trans = StateTrans[{state, newState}];
        // tranition execute
        if (trans == OUT_IN) {
            count++;
        }
        state = newState;
    }
    printf("word count: %d\n", count);
    return 0;
}