increm.cc

#include <atomic>
#include <utility>
#include <functional>

/* goal, replace:
   if(x < 1)
     ++c0_1;
   else if(x < 10)
     ++c1_10;
   else if(x< 100)
     ++c10_100;
   else
     ++cSlow;

   by:

   increm(x, 1, c1, 10, c10, 100, c100, cSlow);
*/


// for cSlow
template<typename T, typename V>
void increm(T val, V& counter)
{
  ++counter;
}

// if we ended up on the last limit/counter pair
template<typename T, typename V>
void increm(T val, T lim, V& counter)
{
  if(val < lim)
    ++counter;

}

// the entry version
template<typename T, typename V, typename... Args>
void increm(T val, T lim, V& counter, Args... args)
{
  if(val < lim)
    ++counter;
  else increm(val, args...);
}

int main(int argc, char** argv)
{
  std::atomic<int> c0_1, c1_10, c10_100, cSlow;


  // this breaks because it does not take a reference to cSlow
  increm(12, 1, c0_1, cSlow);
  
  //     v   l  c   l   c       l    c         c
  increm(12, 1, c0_1, 10, c1_10, 100, c10_100, cSlow);
  
}