gs.cpp

#include <string>
#include <vector>
#include <iostream>
using namespace std;

struct str_pair {
    string u, v;
};

void shift_numeration(vector<string>& v, int k) {
    for (int i = 0; i < v.size(); ++i) {
        string s = v.at(i);
        if ((s.at(0) == '>') || (s.at(0) == '&'))
            v.at(i) = s.at(0) + to_string(stoi(s.substr(1)) + k);
    }
}

bool remove_parentheses(string& s) {
    if ((s.at(0) == '(') && (s.at(s.length()-1) == ')')) {
        s = s.substr(1, s.length()-2);
        return true;
    }
    else
        return false;
}

int last_top_level(string s, char op) {
    int pos = -1;
    int braces_open = 0;
    for (int i = 0; i < s.length(); ++i) {
        char c = s.at(i);
        if (c == '(')
            braces_open++;
        else if (c == ')')
            braces_open--;
        else if ((c == op) && (braces_open == 0))
            pos = i;
    }

    return pos;
}

str_pair unfold(string s, char op) {
    int pos = last_top_level(s, op);
    return str_pair {
        s.substr(0, pos),
        s.substr(pos+1)
    };
}

vector<string> parse(string s) {
    str_pair p;
    vector<string> v;

    if (last_top_level(s, ';') != -1) {
        p = unfold(s, ';');
        remove_parentheses(p.u);
        remove_parentheses(p.v);

        vector<string> l = parse(p.u);
        vector<string> r = parse(p.v);

        int n_l = l.size();
        int n_r = r.size();

        v.push_back(">" + to_string(n_l + 3)); // set jump to second subarray
        shift_numeration(l, 1); // shift left subarray by one
        v.insert(v.end(), l.begin(), l.end( )); // insert the left subarray
        shift_numeration(r, n_l+2); // shift the numeration of right subarray
        v.push_back("&" + to_string(n_l + n_r + 3)); // set jump past second subarray
        v.insert(v.end(), r.begin(), r.end()); // insert the right subarray
    }
    else if (last_top_level(s, ',') != -1) {
        p = unfold(s, ',');

        bool u_par = remove_parentheses(p.u);
        bool v_par = remove_parentheses(p.v);

        vector<string> l = parse(p.u);
        vector<string> r = parse(p.v);

        if (u_par)
            shift_numeration(l, 1);
        if (v_par)
            shift_numeration(r, 1);

        v.insert(v.end(), l.begin(), l.end());
        v.insert(v.end(), r.begin(), r.end());
    }
    else {
        v.push_back(s);
    }
    return v;
}

int main() {
    string s = "A,(a;B),b;C;D";

    vector<string> t = parse(s);
    for (int i = 0; i < t.size(); ++i) {
        cout << i+1 << ". " << t.at(i) << endl;
    }

    return 0;
}