#include <queue>

namespace ... {

class DoWork {

std::queue<int> contexts;

public:

DoWork(int request) {
    contexts.push_back(request);
}

void operator () () {
    while (!contexts.empty()) {
        int request = contexts.pop_front();
        if (...) {
            contexts.push_back(data);
        }
    }
}

};

}