increm3.cc

#include <atomic>
#include <iostream>

/* 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);
*/

using std::cout;
using std::endl;

// for cSlow
template<typename T, typename V>
void increm(T val, V& counter)
{
  cout<<"Last val, we increase anyhow"<<endl;
  ++counter;
}

// if we ended up on the last limit/counter pair
template<typename T, typename V>
void increm(T val, T lim, V& counter)
{
  cout<<"single val: "<<val<<", lim="<<lim<<", current counter="<<counter<<endl;
  if(val < lim) {
    cout<<"We increase!"<<endl;
    ++counter;
  }
  else {
    cout<<"We hit the end & can't recurse"<<endl;
  }
    

}

// the entry version
template<typename T, typename V, typename... Args>
void increm(T val, T lim, V& counter, Args&&... args)
{
  cout<<"mult val: "<<val<<", lim="<<lim<<", current counter="<<counter<<endl;
  if(val < lim) {
    cout<<"We increase & are done"<<endl;
    ++counter;
  } 
  else {
    cout<<"We recurse.."<<endl;
    increm(val, std::forward<Args>(args)...);
  }
}

int main(int argc, char** argv)
{
  std::atomic<int> c0_1{0}, c1_10{0}, c10_100{0}, cSlow{0};

  increm(7, 1, c0_1, 10, c1_10, cSlow);
  

  std::cout<< c0_1<<", "<<c1_10<<", "<<c10_100<<", "<<cSlow<<"\n";

  //     v   l  c        l   c       l    c         c
  increm(120, 1, c0_1, 10, c1_10, 100, c10_100, cSlow);
  
  std::cout<< c0_1<<", "<<c1_10<<", "<<c10_100<<", "<<cSlow<<"\n";
  
}