#include <iostream>
#include <string>
#include <vector>

class Field {
private:
    std::string fieldName;
    std::string fieldValue;
public:
    Field(std::string fieldName) : fieldName(std::move(fieldName)) {}

    Field& operator =(std::string newValue) {
        fieldValue = std::move(newValue);
        return *this;
    }

    std::string& operator()() {
        return fieldValue;
    }
private:

    std::string& get_name() {
        return fieldName;
    }

    friend class Writer;
    friend class Object;
};

class Object {
private:
    friend class Writer;
    std::vector<Field *> fields_;

    std::vector<Field *>& getFields() {
        return fields_;
    }
public:
    Object() = default;

protected:
    void registerField(Field *field) {
        fields_.push_back(field);
    }
};


class Writer {
public:

    void write(std::vector<Object *> objects) {
        if (objects.empty()) return ;
        const auto& fields = objects.front()->fields_;
        for (int i = 0; i < fields.size(); i ++) {
            std::cout << fields[i]->get_name();
            if (i + 1 != fields.size()) std::cout << ",";
        }
        std::cout << "\n";
        for (auto obj : objects) {
            for (int i = 0; i < fields.size(); i ++) {
                std::cout << (*obj->fields_[i])();
                if (i + 1 != fields.size()) std::cout << ",";
            }
            std::cout << "\n";
        }
    }
};


class Agency : public Object {
public:
    Field agencyId;
    Field agencyName;
    Field agencyUrl;

    Agency()
        : agencyId("agency_id")
        , agencyName("agency_name")
        , agencyUrl("agency_url")
    {
        registerField(&agencyId);
        registerField(&agencyName);
        registerField(&agencyUrl);
    }
};

class Stop : public Object {
public:
    Field stopId;
    Field stopName;

    Stop()
        : stopId("stop_id")
        , stopName("stop_name")
    {
        registerField(&stopId);
        registerField(&stopName);
    }
};

int main() {
    Agency a;
    a.agencyName = "Yandex";
    a.agencyId = "123";
    a.agencyUrl = "http://yandex.ru/";

    Stop s;
    s.stopName = "Аптека";
    s.stopId = "2";
    std::vector<Object *> vec;
    vec.push_back(&a);

    Writer w;
    w.write(vec);
    vec.clear();
    vec.push_back(&s);
    w.write(vec);
    return 0;
}