all.hpp

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/* This file is part of OpenKalman, a header-only C++ library for
 * Kalman filters and other recursive filters.
 *
 * Copyright (c) 2025 Christopher Lee Ogden <ogden@gatech.edu>
 *
 * 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/.
 */

#ifndef OPENKALMAN_COLLECTIONS_VIEWS_ALL_HPP
#define OPENKALMAN_COLLECTIONS_VIEWS_ALL_HPP

#ifdef __cpp_lib_ranges
#include <ranges>
#else
#include "basics/compatibility/ranges.hpp"
#include "basics/compatibility/views/range_adaptor_closure.hpp"
#include "basics/compatibility/views/single.hpp"
#endif
#include "collections/concepts/viewable_collection.hpp"
#include "from_tuple.hpp"
#include "to_tuple.hpp"

namespace OpenKalman::collections::views
{
  namespace detail
  {
    struct all_closure
#if __cpp_lib_ranges >= 202202L
      : std::ranges::range_adaptor_closure<all_closure>
#else
      : ranges::range_adaptor_closure<all_closure>
#endif
    {
#ifdef __cpp_concepts
      template<viewable_collection R>
      constexpr collection_view auto
#else
      template<typename R, std::enable_if_t<viewable_collection<R>, int> = 0>
      constexpr auto
#endif
      operator() [[nodiscard]] (R&& r) const
      {
        using namespace std;
        if constexpr (collection_view<R>)
        {
          return static_cast<std::decay_t<R>>(std::forward<R>(r));
        }
        else if constexpr (uniform_tuple_like<R>)
        {
          if constexpr (size_of_v<R> == 1)
  #ifdef __cpp_lib_ranges
            return std::ranges::views::single(OpenKalman::internal::generalized_std_get<0>(std::forward<R>(r)));
  #else
            return ranges::views::single(OpenKalman::internal::generalized_std_get<0>(std::forward<R>(r)));
  #endif
          else return from_tuple {std::forward<R>(r)};
        }
        else // std::ranges::random_access_range<T> and std::ranges::viewable_range<T>
        {
          return to_tuple {std::forward<R>(r)};
        }
      }
    };
  }


  inline constexpr detail::all_closure all;


#ifdef __cpp_concepts
  template<viewable_collection R>
#else
  template<typename R, std::enable_if_t<viewable_collection<R>, int> = 0>
#endif
  using all_t = decltype(all(std::declval<R>()));

}


#endif //OPENKALMAN_COLLECTIONS_VIEWS_ALL_HPP