ratio.hpp

// This file is part of the ACTS project.
//
// Copyright (C) 2016 CERN for the benefit of the ACTS project
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at https://mozilla.org/MPL/2.0/.
 
#pragma once
 
// System include(s)
#include <ratio>
 
namespace detray {

template <typename... ratios>
struct ratio_sum_helper;

template <typename R>
struct ratio_sum_helper<R> {
  using ratio = R;
};

template <typename ratio1, typename ratio2, typename... ratios>
struct ratio_sum_helper<ratio1, ratio2, ratios...> {
  using first_two_sum = std::ratio_add<ratio1, ratio2>;

  using next_helper = ratio_sum_helper<first_two_sum, ratios...>;
 
  // recursive summation of first two std::ratio
  using ratio =
      typename std::conditional_t<sizeof...(ratios) == 0, first_two_sum,
                                  typename next_helper::ratio>;
};


template <typename... ratios>
struct ratio_sum {
  using helper = ratio_sum_helper<ratios...>;
  using ratio = typename helper::ratio;
};

template <typename R>
struct is_ratio_one {
  static constexpr bool value = (R::num == R::den);
};

template <class R>
inline constexpr bool is_ratio_one_v = is_ratio_one<R>::value;
 
}  // namespace detray