traversal_3_variation_step.cpp

struct VariationCount
{
   boost::optional<double> m_initial;
   int m_count;
};

struct CountVariationBiggerThan
{
   CountVariationBiggerThan(double limit) : m_limit(limit) {}
   double m_limit;
   
   VariationCount operator()() const { return VariationCount{}; }
   VariationCount operator()(VariationCount gap, double val) const
   {
      if (!gap.m_initial)
         return VariationCount { val, 0 };
      if (abs(val - *gap.m_initial) > m_limit)
         gap.m_count++;
      return gap;
   }
};