Map reduce context

[neozhangthe1]

for mabo: context in map reduce function use case:

struct alpha_beta_type {
    int alpha;
    int beta;

    alpha_beta_type() :
            alpha(-1), beta(-1) {
    }
    alpha_beta_type(int alpha_beta, bool inside) {
        alpha = -1;
        beta = -1;
        if (inside) {
            beta = alpha_beta;
        } else {
            alpha = alpha_beta;
        }
    }

    alpha_beta_type& operator+=(const alpha_beta_type& other) {
        if (other.beta > -1) {
            if (beta > -1) {
                beta = std::min(beta, other.beta);
            } else {
                beta = other.beta;
            }
        } else if (other.alpha > -1) {
            if (alpha > -1) {
                alpha = std::max(alpha, other.alpha);
            } else {
                alpha = other.alpha;
            }
        }
        std::cout << " alpha:" << alpha << " beta:" << beta << endl;
        return *this;
    }

    static alpha_beta_type aggregator(icontext_type& context, graph_type::vertex_type& vertex) {
        std::cout << "id:" << vertex.id() << " inside: " << vertex.data().inside
                << " alpha:" << vertex.data().alpha_beta << std::endl;
        return alpha_beta_type(vertex.data().alpha_beta, vertex.data().inside);
    }
};