brainfuckインタプリタ仮置き

bf.cpp

#include<bits/stdc++.h>

using namespace std;

template<size_t buffer_size = 1024>
class Brainfucker{
public:
    string code;
    string input;
    string output;
    // vector<int> buffer(buffer_size);
    char buffer[buffer_size];
    size_t ptr_c = 0;
    size_t ptr_v = 0;
    size_t ptr_i = 0;
    
    int fault = 0; // 本当はenum作るべき
    // 1: ptr_v error / 2: not found ']' / 3: not found '['
    
    Brainfucker(const string& c,const string& i):code(c),input(i){reset();}
    Brainfucker(const string& c):code(c){reset();}
    Brainfucker(){reset();}
    
    void reset(){
        output.clear();
        ptr_v = ptr_c = ptr_i = 0;
        fault = 0;
        fill(buffer,buffer+buffer_size,0);
    }
    
    bool is_halt(){
        return ptr_c == code.size() || fault;
    }
    
    bool step(){
        if (is_halt()) return false;
        switch(code[ptr_c]){
            case '+':
                if (ptr_v < 0 || buffer_size <= ptr_v){
                    fault = 1;
                    return false;
                }
                buffer[ptr_v]=(buffer[ptr_v]+1)&255;
                break;
            case '-':
                if (ptr_v < 0 || buffer_size <= ptr_v){
                    fault = 1;
                    return false;
                }
                buffer[ptr_v]=(buffer[ptr_v]-1)&255;
                break;
            case '>':
                ptr_v++;
                break;
            case '<':
                ptr_v--;
                break;
            case '[':
                if (buffer[ptr_v]==0)
                    while (ptr_c < code.size()-1 && code[++ptr_c]!=']');
                if (ptr_c == code.size()){
                    fault = 2;
                    return false;
                }
                break;
            case ']':
                if (buffer[ptr_v]!=0)
                    while (0 < ptr_c && code[--ptr_c]!='[');
                if (ptr_c == -1){
                    fault = 3;
                    return false;
                }
                break;
            case ',':
                if (ptr_i < input.size())
                    buffer[ptr_v]=input[ptr_i++];
                else
                    buffer[ptr_v]=0;
                break;
            case '.':
                output.push_back(buffer[ptr_v]);
                break;
            default:
                break;
        }
        ptr_c++;
        return true;
    }
    
    void run(long long count = -1){
        while (step() && --count);
    }
};


int m,n;

int main(){
    int i,j,k;
    
    Brainfucker<> bf(">++++++++[<+++++++++>-]<.>++++[<+++++++>-]<+.+++++++..+++.>++++[<------>-]<.>++++[<++++++>-]<.+++.------.--------.");
    
    bf.run();
    
    cout << bf.output << endl;

    return 0;
}