ValueIndexPairSorting.h

/**************************************************************************
 * BASF2 (Belle Analysis Framework 2)                                     *
 * Copyright(C) 2019  Belle II Collaboration                              *
 *                                                                        *
 * Author: The Belle II Collaboration                                     *
 * Contributors: Frank Meier                                              *
 *                                                                        *
 * This software is provided "as is" without any warranty.                *
 **************************************************************************/
 
#pragma once
 
#include <utility>
 
namespace Belle2 {
  namespace ValueIndexPairSorting {
 
    template <class T>
    auto higherPair = [](const T& a, const T& b) -> bool {
      // always put NaN to the end
      if (std::isnan(a.first)) return false;
      if (std::isnan(b.first)) return true;
      return a.first > b.first;
    };
 
    template <class T>
    auto lowerPair = [](const T& a, const T& b) -> bool {
      // always put NaN to the end
      if (std::isnan(a.first)) return false;
      if (std::isnan(b.first)) return true;
      return a.first < b.first;
    };
  }
}