minmax_transformed_element.h

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// This file's extension implies that it's C, but it's really -*- C++ -*-.
/*
 * Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration.
 */
#ifndef CXXUTILS_MINMAX_TRANSFORMED_ELEMENT_H
#define CXXUTILS_MINMAX_TRANSFORMED_ELEMENT_H
 
 
#include <ranges>
#include <utility>
#include <cstdlib>
 
 
namespace CxxUtils {
 
 
template <class RANGE, class FUNC>
inline
auto min_transformed_element (RANGE&& r, FUNC&& f)
{
  if (std::ranges::empty (r)) std::abort();
  auto it = std::ranges::begin(r);
  auto itmin = it;
  auto val = f(*it);
  for (++it; it != std::ranges::end(r); ++it) {
    auto val2 = f(*it);
    if (val2 < val) {
      val = val2;
      itmin = it;
    }
  }
  return std::make_pair (val, itmin);
}
 
 
template <class RANGE, class FUNC>
inline
auto max_transformed_element (RANGE&& r, FUNC&& f)
{
  if (std::ranges::empty (r)) std::abort();
  auto it = std::ranges::begin(r);
  auto itmax = it;
  auto val = f(*it);
  for (++it; it != std::ranges::end(r); ++it) {
    auto val2 = f(*it);
    if (val2 > val) {
      val = val2;
      itmax = it;
    }
  }
  return std::make_pair (val, itmax);
}
 
 
} // namespace CxxUtils
 
 
#endif // not CXXUTILS_MINMAX_TRANSFORMED_ELEMENT_H