Method empty

compute/perf/perf_tbb_merge.cpp:28–28

where to put merged sequence

    Iterator begin2, end2; // [begin2,end2) is 2nd sequence to be merged
    Iterator out;               // where to put merged sequence
    bool empty()   const {return (end1-begin1)+(end2-begin2)==0;}
    bool is_divisible() const {
        return (std::min)( end1-begin1, end2-begin2 ) > grainsize;
    }