TriangularAdapter.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) 2019-2024 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_TRIANGULARADAPTER_HPP
#define OPENKALMAN_TRIANGULARADAPTER_HPP

#include "linear-algebra/traits/triangle_type_of.hpp"

namespace OpenKalman
{
#ifdef __cpp_concepts
  template<square_shaped<applicability::permitted> NestedObject, triangle_type tri>
    requires (index_count_v<NestedObject> <= 2)
#else
  template<typename NestedObject, triangle_type tri>
#endif
  struct TriangularAdapter : OpenKalman::internal::AdapterBase<TriangularAdapter<NestedObject, tri>, NestedObject>
  {

#ifndef __cpp_concepts
    static_assert(square_shaped<NestedObject, applicability::permitted>);
    static_assert(index_count_v<NestedObject> <= 2);
#endif

  private:

    using Base = OpenKalman::internal::AdapterBase<TriangularAdapter, NestedObject>;

    static constexpr auto dim = dynamic_dimension<NestedObject, 0> ? index_dimension_of_v<NestedObject, 1> :
      index_dimension_of_v<NestedObject, 0>;

    template<typename Arg>
    static bool constexpr dimensions_match = dimension_size_of_index_is<Arg, 0, dim, applicability::permitted> and
      dimension_size_of_index_is<Arg, 1, dim, applicability::permitted>;

  public:

    using Scalar = scalar_type_of_t<NestedObject>;


#ifdef __cpp_concepts
    TriangularAdapter() requires std::default_initializable<NestedObject> and (not has_dynamic_dimensions<NestedObject>)
#else
    template<bool Enable = true, std::enable_if_t<Enable and
      stdex::default_initializable<NestedObject> and (not has_dynamic_dimensions<NestedObject>), int> = 0>
    TriangularAdapter()
#endif
      : Base {} {}


#ifdef __cpp_concepts
    template<triangular_adapter Arg> requires (not std::is_base_of_v<TriangularAdapter, std::decay_t<Arg>>) and
      triangular_matrix<Arg, tri> and (not diagonal_matrix<NestedObject>) and
      dimensions_match<nested_object_of_t<Arg>> and
# if OPENKALMAN_CPP_FEATURE_CONCEPTS
      requires(Arg&& arg) { NestedObject {nested_object(std::forward<Arg>(arg))}; } //-- not accepted in GCC 10.1.0
# else
      std::constructible_from<NestedObject, decltype(nested_object(std::declval<Arg&&>()))>
# endif
#else
    template<typename Arg, std::enable_if_t<triangular_adapter<Arg> and (not std::is_base_of_v<TriangularAdapter, std::decay_t<Arg>>) and
      (triangular_matrix<Arg, tri>) and (not diagonal_matrix<NestedObject>) and
      dimensions_match<typename nested_object_of<Arg>::type> and
      std::is_constructible<NestedObject, decltype(nested_object(std::declval<Arg&&>()))>::value, int> = 0>
#endif
    TriangularAdapter(Arg&& arg) : Base {nested_object(std::forward<Arg>(arg))} {}


#ifdef __cpp_concepts
    template<square_shaped<applicability::permitted> Arg> requires (not triangular_matrix<Arg, tri>) and
      (not diagonal_matrix<NestedObject>) and dimensions_match<Arg> and std::constructible_from<NestedObject, Arg&&>
#else
    template<typename Arg, std::enable_if_t<square_shaped<Arg, applicability::permitted> and
      (not triangular_matrix<Arg, tri>) and (not diagonal_matrix<NestedObject>) and
      dimensions_match<Arg> and stdex::constructible_from<NestedObject, Arg&&>, int> = 0>
#endif
    explicit TriangularAdapter(Arg&& arg) : Base {
      [](Arg&& arg) -> decltype(auto) {
          if constexpr (has_dynamic_dimensions<Arg>) if (not is_square_shaped(arg)) throw std::invalid_argument {
            "Argument to TriangularAdapter must be a square matrix, but the argument has dimensions " +
            std::to_string(get_index_dimension_of<0>(arg)) + "×" + std::to_string(get_index_dimension_of<1>(arg)) +
            " in " + __func__ + " at line " + std::to_string(__LINE__) + " of " + __FILE__};
          return std::forward<Arg>(arg);
      }(std::forward<Arg>(arg))
    } {}


#ifdef __cpp_concepts
    template<triangular_matrix<tri> Arg> requires (not triangular_adapter<Arg>) and
      (not has_nested_object<Arg> or (diagonal_matrix<NestedObject> and diagonal_matrix<Arg>)) and
      dimensions_match<Arg> and std::constructible_from<NestedObject, Arg&&>
#else
    template<typename Arg, std::enable_if_t<triangular_matrix<Arg, tri> and (not triangular_adapter<Arg>) and
      (not has_nested_object<Arg> or (diagonal_matrix<NestedObject> and diagonal_matrix<Arg>)) and
      dimensions_match<Arg> and std::is_constructible<NestedObject, Arg&&>::value, int> = 0>
#endif
    TriangularAdapter(Arg&& arg) : Base {std::forward<Arg>(arg)} {}


#ifdef __cpp_concepts
    template<diagonal_matrix Arg> requires (not std::is_base_of_v<TriangularAdapter, std::decay_t<Arg>>) and
      diagonal_matrix<NestedObject> and dimensions_match<Arg> and (not std::constructible_from<NestedObject, Arg&&>) and
      requires(Arg&& arg) { NestedObject {diagonal_of(std::forward<Arg>(arg))}; }
#else
    template<typename Arg, std::enable_if_t<(not std::is_base_of_v<TriangularAdapter, std::decay_t<Arg>>) and
      diagonal_matrix<NestedObject> and dimensions_match<Arg> and (not stdex::constructible_from<NestedObject, Arg&&>) and
      std::is_constructible<NestedObject, decltype(diagonal_of(std::declval<Arg&&>()))>::value, int> = 0>
#endif
    TriangularAdapter(Arg&& arg) : Base {diagonal_of(std::forward<Arg>(arg))} {}


#ifdef __cpp_concepts
    template<square_shaped<applicability::permitted> Arg> requires (not triangular_matrix<Arg>) and diagonal_matrix<NestedObject> and
      dimensions_match<Arg> and requires(Arg&& arg) { NestedObject {diagonal_of(std::forward<Arg>(arg))}; }
#else
    template<typename Arg, std::enable_if_t<square_shaped<Arg, applicability::permitted> and
      (not triangular_matrix<Arg>) and diagonal_matrix<NestedObject> and
      dimensions_match<Arg> and std::is_constructible<NestedObject, decltype(diagonal_of(std::declval<Arg&&>()))>::value, int> = 0>
#endif
    explicit TriangularAdapter(Arg&& arg) : Base {
      [](Arg&& arg) -> decltype(auto) {
          if constexpr (has_dynamic_dimensions<Arg>) if (not is_square_shaped(arg)) throw std::invalid_argument {
            "Argument to TriangularAdapter must be a square matrix, but the argument has dimensions " +
            std::to_string(get_index_dimension_of<0>(arg)) + "×" + std::to_string(get_index_dimension_of<1>(arg)) +
            " in " + __func__ + " at line " + std::to_string(__LINE__) + " of " + __FILE__};
          return diagonal_of(std::forward<Arg>(arg));
      }(std::forward<Arg>(arg))
    } {}


#ifdef __cpp_concepts
    template<std::convertible_to<const Scalar>...Args> requires (sizeof...(Args) > 0) and
      (tri != triangle_type::diagonal) and (not diagonal_matrix<NestedObject>) and
      requires(Args...args) { NestedObject {make_dense_object_from<NestedObject>(static_cast<const Scalar>(args)...)}; }
#else
    template<typename...Args, std::enable_if_t<std::conjunction_v<std::is_convertible<Args, const Scalar>...> and
      (sizeof...(Args) > 0) and (tri != triangle_type::diagonal) and (not diagonal_matrix<NestedObject>), int> = 0>
#endif
    TriangularAdapter(Args...args)
      : Base {make_dense_object_from<NestedObject>(static_cast<const Scalar>(args)...)} {}


#if defined(__cpp_concepts) and OPENKALMAN_CPP_FEATURE_CONCEPTS
    template<std::convertible_to<const Scalar>...Args> requires (sizeof...(Args) > 0) and
      (tri == triangle_type::diagonal or diagonal_matrix<NestedObject>) and
      requires(Args ... args) { NestedObject {
        to_diagonal(make_dense_object_from<NestedObject>(
          std::tuple<Dimensions<sizeof...(Args)>, Dimensions<1>>{}, static_cast<const Scalar>(args)...))}; }
#else
    template<typename ... Args, std::enable_if_t<std::conjunction_v<std::is_convertible<Args, const Scalar>...> and
      (sizeof...(Args) > 0) and (tri == triangle_type::diagonal or diagonal_matrix<NestedObject>), int> = 0>
#endif
    TriangularAdapter(Args...args) : Base {to_diagonal(make_dense_object_from<NestedObject>(
      std::tuple<Dimensions<sizeof...(Args)>, Dimensions<1>>{}, static_cast<const Scalar>(args)...))} {}


#ifdef __cpp_concepts
    template<triangular_matrix<tri> Arg> requires
      (not std::is_base_of_v<TriangularAdapter, std::decay_t<Arg>>) and
      vector_space_descriptors_may_match_with<NestedObject, Arg> and
      (not values::fixed<constant_diagonal_value<NestedObject>> or
        requires { requires constant_diagonal_value<NestedObject>::value == constant_diagonal_value<Arg>::value; }) and
      (not (diagonal_matrix<NestedObject> or tri == triangle_type::diagonal) or diagonal_matrix<Arg>)
#else
    template<typename Arg, std::enable_if_t<triangular_matrix<Arg, tri> and
      (not std::is_base_of_v<TriangularAdapter, std::decay_t<Arg>>) and vector_space_descriptors_may_match_with<NestedObject, Arg> and
      (not constant_diagonal_matrix<NestedObject> or constant_diagonal_matrix<Arg>) and
      (not (diagonal_matrix<NestedObject> or tri == triangle_type::diagonal) or diagonal_matrix<Arg>), int> = 0>
#endif
    auto& operator=(Arg&& arg)
    {
      if constexpr (not constant_diagonal_matrix<NestedObject>)
        internal::set_triangle<tri>(this->nested_object(), std::forward<Arg>(arg));
      return *this;
    }


#ifdef __cpp_concepts
    template<vector_space_descriptors_may_match_with<NestedObject> Arg, triangle_type t>
#else
    template<typename Arg, triangle_type t, std::enable_if_t<vector_space_descriptors_may_match_with<Arg, NestedObject>, int> = 0>
#endif
    auto& operator+=(const TriangularAdapter<Arg, tri>& arg)
    {
      internal::set_triangle<tri>(this->nested_object(), this->nested_object() + std::forward<Arg>(arg));
      return *this;
    }


#ifdef __cpp_concepts
    template<vector_space_descriptors_may_match_with<NestedObject> Arg, triangle_type t>
#else
    template<typename Arg, triangle_type t, std::enable_if_t<vector_space_descriptors_may_match_with<Arg, NestedObject>, int> = 0>
#endif
    auto& operator-=(const TriangularAdapter<Arg, tri>& arg)
    {
      internal::set_triangle<tri>(this->nested_object(), this->nested_object() - std::forward<Arg>(arg));
      return *this;
    }


#ifdef __cpp_concepts
    template<std::convertible_to<Scalar> S>
#else
    template<typename S, std::enable_if_t<stdex::convertible_to<S, Scalar>, int> = 0>
#endif
    auto& operator*=(const S s)
    {
      internal::set_triangle<tri>(this->nested_object(), scalar_product(this->nested_object(), s));
      return *this;
    }


#ifdef __cpp_concepts
    template<std::convertible_to<Scalar> S>
#else
    template<typename S, std::enable_if_t<stdex::convertible_to<S, Scalar>, int> = 0>
#endif
    auto& operator/=(const S s)
    {
      internal::set_triangle<tri>(this->nested_object(), scalar_quotient(this->nested_object(), s));
      return *this;
    }


#ifdef __cpp_concepts
    template<vector_space_descriptors_may_match_with<NestedObject> Arg>
#else
    template<typename Arg, std::enable_if_t<vector_space_descriptors_may_match_with<Arg, NestedObject>, int> = 0>
#endif
    auto& operator*=(const TriangularAdapter<Arg, tri>& arg)
    {
      contract_in_place(this->nested_object(), to_dense_object(arg));
      return *this;
    }


#ifdef __cpp_concepts
    template<typename Arg> requires std::same_as<std::decay_t<Arg>, TriangularAdapter>
    friend decltype(auto) operator-(Arg&& arg)
    {
      return make_triangular_matrix<triangle_type_of_v<Arg>>(-nested_object(std::forward<Arg>(arg)));
    }
#else
    decltype(auto) operator-() const&
    {
      return make_triangular_matrix<tri>(-nested_object(*this));
    }

    decltype(auto) operator-() const&&
    {
      return make_triangular_matrix<tri>(-nested_object(std::move(*this)));
    }
#endif


#ifdef __cpp_concepts
    template<typename Arg, std::convertible_to<const scalar_type_of_t<Arg>> S> requires std::same_as<std::decay_t<Arg>, TriangularAdapter>
#else
    template<typename Arg, typename S, std::enable_if_t<
      std::is_same_v<std::decay_t<Arg>, TriangularAdapter> and stdex::convertible_to<S, const scalar_type_of_t<Arg>>>>
#endif
    friend decltype(auto) operator*(Arg&& arg, S s)
    {
      return make_triangular_matrix<triangle_type_of_v<Arg>>(nested_object(std::forward<Arg>(arg)) * s);
    }


#ifdef __cpp_concepts
    template<typename Arg, std::convertible_to<const scalar_type_of_t<Arg>> S> requires std::same_as<std::decay_t<Arg>, TriangularAdapter>
#else
    template<typename Arg, typename S, std::enable_if_t<
      std::is_same_v<std::decay_t<Arg>, TriangularAdapter> and stdex::convertible_to<S, const scalar_type_of_t<Arg>>>>
#endif
    friend decltype(auto) operator*(S s, Arg&& arg)
    {
      return make_triangular_matrix<triangle_type_of_v<Arg>>(s * nested_object(std::forward<Arg>(arg)));
    }


#ifdef __cpp_concepts
    template<typename Arg, std::convertible_to<const scalar_type_of_t<Arg>> S> requires std::same_as<std::decay_t<Arg>, TriangularAdapter>
#else
    template<typename Arg, typename S, std::enable_if_t<
      std::is_same_v<std::decay_t<Arg>, TriangularAdapter> and stdex::convertible_to<S, const scalar_type_of_t<Arg>>>>
#endif
    friend decltype(auto) operator/(Arg&& arg, S s)
    {
      return make_triangular_matrix<triangle_type_of_v<Arg>>(nested_object(std::forward<Arg>(arg)) / s);
    }

  };


  // ------------------------------- //
  //        Deduction Guides         //
  // ------------------------------- //

#ifdef __cpp_concepts
  template<triangular_matrix M>
#else
  template<typename M, std::enable_if_t<triangular_matrix<M>, int> = 0>
#endif
  TriangularAdapter(M&&) -> TriangularAdapter<
    std::conditional_t<triangular_adapter<M>, nested_object_of_t<M>, M>,
    triangle_type_of_v<M>>;


#ifdef __cpp_concepts
  template<hermitian_matrix<applicability::permitted> M> requires (not triangular_matrix<M>)
#else
  template<typename M, std::enable_if_t<hermitian_matrix<M, applicability::permitted> and
    (not triangular_matrix<M>), int> = 0>
#endif
  explicit TriangularAdapter(M&&) -> TriangularAdapter<
    std::conditional_t<hermitian_adapter<M>, nested_object_of_t<M>, M>,
    hermitian_adapter<M, HermitianAdapterType::upper> ? triangle_type::upper : triangle_type::lower>;


#ifdef __cpp_concepts
  template<indexible M> requires (not triangular_matrix<M>) and
    (not hermitian_matrix<M, applicability::permitted>)
#else
  template<typename M, std::enable_if_t<indexible<M> and (not triangular_matrix<M>) and
      (not hermitian_matrix<M, applicability::permitted>), int> = 0>
#endif
  explicit TriangularAdapter(M&&) -> TriangularAdapter<M, triangle_type::lower>;


  // ------------------------- //
  //        Interfaces         //
  // ------------------------- //

  namespace interface
  {
    template<typename NestedObject, triangle_type tri>
    struct object_traits<TriangularAdapter<NestedObject, tri>>
    {
      using scalar_type = scalar_type_of_t<NestedObject>;


      template<typename Arg>
      static constexpr auto count_indices(const Arg& arg) { return std::integral_constant<std::size_t, 2>{}; }


      template<typename Arg, typename N>
      static constexpr auto get_pattern_collection(Arg&& arg, N n)
      {
        return internal::most_fixed_pattern(
          OpenKalman::get_pattern_collection<0>(nested_object(arg)),
          OpenKalman::get_pattern_collection<1>(nested_object(arg)));
      }


      template<typename Arg>
      static decltype(auto) nested_object(Arg&& arg)
      {
        return std::forward<Arg>(arg).nested_object();
      }


      template<typename Arg>
      static constexpr auto get_constant_diagonal(const Arg& arg)
      {
        if constexpr (tri == triangle_type::diagonal and not diagonal_matrix<NestedObject>)
          return constant_value{OpenKalman::nested_object(arg)};
        else
          return constant_diagonal_value{OpenKalman::nested_object(arg)};
      }


      template<applicability b>
      static constexpr bool one_dimensional = OpenKalman::one_dimensional<NestedObject, b>;


      template<applicability b>
      static constexpr bool is_square = OpenKalman::square_shaped<NestedObject, b>;


      static constexpr triangle_type triangle_type_value = tri * triangle_type_of_v<NestedObject>;


      static constexpr bool is_triangular_adapter = true;


      static constexpr bool is_writable = false;


#ifdef __cpp_lib_concepts
      template<typename Arg> requires OpenKalman::one_dimensional<nested_object_of_t<Arg&>> and raw_data_defined_for<nested_object_of_t<Arg&>>
#else
      template<typename Arg, std::enable_if_t<one_dimensional<typename nested_object_of<Arg&>::type> and
        raw_data_defined_for<typename nested_object_of<Arg&>::type>, int> = 0>
#endif
      static constexpr auto * const
      raw_data(Arg& arg) { return internal::raw_data(OpenKalman::nested_object(arg)); }


      static constexpr data_layout layout = OpenKalman::one_dimensional<NestedObject> ? layout_of_v<NestedObject> : data_layout::none;

    };

  }

}


#endif