persistence_interval.h

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/*    This file is part of the Gudhi Library - https://gudhi.inria.fr/ - which is released under MIT.
 *    See file LICENSE or go to https://gudhi.inria.fr/licensing/ for full license details.
 *    Author(s):       Hannah Schreiber
 *
 *    Copyright (C) 2024 Inria
 *
 *    Modification(s):
 *      - YYYY/MM Author: Description of the modification
 */

 
#ifndef PM_INTERVAL_INCLUDED
#define PM_INTERVAL_INCLUDED
 
#include <ostream>  //std::ostream
#include <limits>   //std::numeric_limits
#include <tuple>
#include <utility>  //std::move
 
namespace Gudhi {
namespace persistence_matrix {

template <typename Dimension, typename Event_value>
struct Persistence_interval {
  static constexpr Event_value inf = std::numeric_limits<Event_value>::has_infinity
                                         ? std::numeric_limits<Event_value>::infinity()
                                         : static_cast<Event_value>(-1);

  Persistence_interval(Event_value birth = inf, Event_value death = inf, Dimension dim = -1)
      : dim(dim), birth(birth), death(death)
  {}
 
  Dimension dim;     
  Event_value birth; 
  Event_value death; 

  friend std::ostream& operator<<(std::ostream& stream, const Persistence_interval& interval)
  {
    stream << "[" << interval.dim << "] ";
    if constexpr (std::numeric_limits<Event_value>::has_infinity) {
      stream << interval.birth << " - " << interval.death;
    } else {
      if (interval.birth == inf)
        stream << "inf";
      else
        stream << interval.birth;
      stream << " - ";
      if (interval.death == inf)
        stream << "inf";
      else
        stream << interval.death;
    }
    return stream;
  }

  template <std::size_t I>
  constexpr auto& get() & noexcept
  {
    static_assert(I < 3, "Value mismatch at argument 1 in template parameter list. Maximal possible value is 2.");
 
    if constexpr (I == 0) return birth;
    if constexpr (I == 1) return death;
    if constexpr (I == 2) return dim;
  }

  template <std::size_t I>
  constexpr const auto& get() const& noexcept
  {
    static_assert(I < 3, "Value mismatch at argument 1 in template parameter list. Maximal possible value is 2.");
 
    if constexpr (I == 0) return birth;
    if constexpr (I == 1) return death;
    if constexpr (I == 2) return dim;
  }

  template <std::size_t I>
  constexpr auto&& get() && noexcept
  {
    static_assert(I < 3, "Value mismatch at argument 1 in template parameter list. Maximal possible value is 2.");
 
    if constexpr (I == 0) return std::move(birth);
    if constexpr (I == 1) return std::move(death);
    if constexpr (I == 2) return std::move(dim);
  }

  template <std::size_t I>
  constexpr const auto&& get() const&& noexcept
  {
    static_assert(I < 3, "Value mismatch at argument 1 in template parameter list. Maximal possible value is 2.");
 
    if constexpr (I == 0) return std::move(birth);
    if constexpr (I == 1) return std::move(death);
    if constexpr (I == 2) return std::move(dim);
  }
};
 
}  // namespace persistence_matrix
}  // namespace Gudhi
 
namespace std {

template <typename Dimension, typename Event_value>
struct tuple_size<Gudhi::persistence_matrix::Persistence_interval<Dimension, Event_value> >
    : integral_constant<size_t, 3> {};

template <size_t I, typename Dimension, typename Event_value>
struct tuple_element<I, Gudhi::persistence_matrix::Persistence_interval<Dimension, Event_value> > {
  static_assert(I < 3, "Value mismatch at argument 1 in template parameter list. Maximal possible value is 2.");
 
  using type = conditional_t < I<2, Event_value, Dimension>;
};

template <size_t I, typename Dimension, typename Event_value>
constexpr auto& get(Gudhi::persistence_matrix::Persistence_interval<Dimension, Event_value>& i) noexcept
{
  return i.template get<I>();
}

template <size_t I, typename Dimension, typename Event_value>
constexpr const auto& get(const Gudhi::persistence_matrix::Persistence_interval<Dimension, Event_value>& i) noexcept
{
  return i.template get<I>();
}

template <size_t I, typename Dimension, typename Event_value>
constexpr auto&& get(Gudhi::persistence_matrix::Persistence_interval<Dimension, Event_value>&& i) noexcept
{
  return std::move(i).template get<I>();
}

template <size_t I, typename Dimension, typename Event_value>
constexpr const auto&& get(const Gudhi::persistence_matrix::Persistence_interval<Dimension, Event_value>&& i) noexcept
{
  return std::move(i).template get<I>();
}
 
}  // namespace std
 
#endif  // PM_INTERVAL_INCLUDED