tpl_ca_multi_field_lattice.H

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/*
                          Aleph_w
 
  Data structures & Algorithms
  version 2.0.0b
  https://github.com/lrleon/Aleph-w
 
  This file is part of Aleph-w library
 
  Copyright (c) 2002-2026 Leandro Rabindranath Leon
 
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  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
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  copies of the Software, and to permit persons to whom the Software is
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*/
 
#ifndef TPL_CA_MULTI_FIELD_LATTICE_H
#define TPL_CA_MULTI_FIELD_LATTICE_H
 
#include <array>
#include <concepts>
#include <cstddef>
#include <tuple>
#include <type_traits>
#include <utility>
 
#include <ah-errors.H>
 
#include <ca-traits.H>
#include <tpl_ca_concepts.H>
#include <tpl_ca_lattice.H>
#include <tpl_ca_storage.H>
 
namespace Aleph {
namespace CA {
 
struct Layout_AoS
{
};
 
struct Layout_SoA
{
};
 
namespace ca_mf_detail {
 
template <std::size_t... I>
using index_seq = std::index_sequence<I...>;
 
template <std::size_t Rank, typename Boundary, typename... Fields>
using soa_storages = std::tuple<Lattice<Dense_Cell_Storage<Fields, Rank>, Boundary>...>;
 
template <typename... Fields>
using aos_cell = std::tuple<Fields...>;
 
template <std::size_t Rank, typename Boundary, typename... Fields>
using aos_lattice = Lattice<Dense_Cell_Storage<aos_cell<Fields...>, Rank>, Boundary>;
 
}  // namespace ca_mf_detail
 
template <typename Layout, typename Boundary, std::size_t Rank, typename... Fields>
class Multi_Field_Lattice
{
  static_assert(sizeof...(Fields) >= 1, "Multi_Field_Lattice requires at least one field");
  static_assert((CellState<Fields> and ...), "Every field type must satisfy CellState");
  static_assert(std::is_same_v<Layout, Layout_AoS> or std::is_same_v<Layout, Layout_SoA>,
                "Layout must be Layout_AoS or Layout_SoA");
 
public:
  using layout_type = Layout;
  using boundary_type = Boundary;
  using coord_type = Coord_Vec<Rank>;
  using extents_type = std::array<ca_size_t, Rank>;
  static constexpr std::size_t field_count = sizeof...(Fields);
  static constexpr std::size_t rank = Rank;
  using field_types = std::tuple<Fields...>;
 
  template <std::size_t I>
  using field_type = std::tuple_element_t<I, field_types>;
 
private:
  // Pick the underlying representation based on the layout tag.
  using soa_storage_type = ca_mf_detail::soa_storages<Rank, Boundary, Fields...>;
  using aos_lattice_type = ca_mf_detail::aos_lattice<Rank, Boundary, Fields...>;
 
  using storage_type
    = std::conditional_t<std::is_same_v<Layout, Layout_SoA>, soa_storage_type, aos_lattice_type>;
 
  storage_type store_{};
  extents_type extents_{};
 
  // ---------------------------------------------------------------------
  // SoA construction helpers
  // ---------------------------------------------------------------------
  template <std::size_t... I>
  static soa_storage_type make_soa(const extents_type &ext, ca_mf_detail::index_seq<I...>)
  {
    return soa_storage_type{Lattice<Dense_Cell_Storage<Fields, Rank>, Boundary>(ext, Fields{})...};
  }
 
  template <std::size_t... I>
  static soa_storage_type make_soa_init(const extents_type &ext,
                                        const std::tuple<Fields...> &init,
                                        ca_mf_detail::index_seq<I...>)
  {
    return soa_storage_type{
      Lattice<Dense_Cell_Storage<Fields, Rank>, Boundary>(ext, std::get<I>(init))...};
  }
 
public:
  Multi_Field_Lattice() = default;
 
  explicit Multi_Field_Lattice(const extents_type &ext) : extents_(ext)
  {
    if constexpr (std::is_same_v<Layout, Layout_SoA>)
      store_ = make_soa(ext, std::index_sequence_for<Fields...>{});
    else
      store_ = aos_lattice_type(ext, ca_mf_detail::aos_cell<Fields...>{});
  }
 
  Multi_Field_Lattice(const extents_type &ext, const std::tuple<Fields...> &init) : extents_(ext)
  {
    if constexpr (std::is_same_v<Layout, Layout_SoA>)
      store_ = make_soa_init(ext, init, std::index_sequence_for<Fields...>{});
    else
      store_ = aos_lattice_type(ext, init);
  }
 
  // ---------------------------------------------------------------------
  // Geometry
  // ---------------------------------------------------------------------
 
  [[nodiscard]] static constexpr std::size_t dimension() noexcept
  {
    return Rank;
  }
 
  [[nodiscard]] ca_size_t size() const noexcept
  {
    ca_size_t n = 1;
    for (std::size_t d = 0; d < Rank; ++d)
      n *= extents_[d];
    return n;
  }
 
  [[nodiscard]] ca_size_t size(const std::size_t d) const
  {
    ah_out_of_range_error_if(d >= Rank) << "Multi_Field_Lattice::size: axis " << d << " out of range";
    return extents_[d];
  }
 
  [[nodiscard]] const extents_type &extents() const noexcept
  {
    return extents_;
  }
 
  // ---------------------------------------------------------------------
  // Per-field access (uniform across layouts)
  // ---------------------------------------------------------------------
 
  template <std::size_t I>
  [[nodiscard]] field_type<I> at(const coord_type &c) const
  {
    static_assert(I < field_count, "field index out of range");
    if constexpr (std::is_same_v<Layout, Layout_SoA>)
      return std::get<I>(store_).at(c);
    else
      return std::get<I>(store_.at(c));
  }
 
  template <std::size_t I>
  [[nodiscard]] field_type<I> at_safe(const coord_type &c) const
  {
    static_assert(I < field_count, "field index out of range");
    if constexpr (std::is_same_v<Layout, Layout_SoA>)
      return std::get<I>(store_).at_safe(c);
    else
      return std::get<I>(store_.at_safe(c));
  }
 
  template <std::size_t I, typename V>
  void set(const coord_type &c, const V &v)
  {
    static_assert(I < field_count, "field index out of range");
    if constexpr (std::is_same_v<Layout, Layout_SoA>)
      {
        std::get<I>(store_).set(c, static_cast<field_type<I>>(v));
      }
    else
      {
        ca_mf_detail::aos_cell<Fields...> cell = store_.at(c);
        std::get<I>(cell) = static_cast<field_type<I>>(v);
        store_.set(c, cell);
      }
  }
 
  void set_cell(const coord_type &c, const std::tuple<Fields...> &cell)
  {
    if constexpr (std::is_same_v<Layout, Layout_SoA>)
      set_cell_impl(c, cell, std::index_sequence_for<Fields...>{});
    else
      store_.set(c, cell);
  }
 
  [[nodiscard]] std::tuple<Fields...> at_cell(const coord_type &c) const
  {
    if constexpr (std::is_same_v<Layout, Layout_SoA>)
      return at_cell_impl(c, std::index_sequence_for<Fields...>{});
    else
      return store_.at(c);
  }
 
  // ---------------------------------------------------------------------
  // SoA-only: hand a single-field Lattice<> to the legacy mono-field
  // engines.
  // ---------------------------------------------------------------------
 
  template <std::size_t I>
  [[nodiscard]] auto &field()
    requires std::is_same_v<Layout, Layout_SoA>
  {
    static_assert(I < field_count, "field index out of range");
    return std::get<I>(store_);
  }
 
  template <std::size_t I>
  [[nodiscard]] const auto &field() const
    requires std::is_same_v<Layout, Layout_SoA>
  {
    static_assert(I < field_count, "field index out of range");
    return std::get<I>(store_);
  }
 
  // ---------------------------------------------------------------------
  // Bulk operations
  // ---------------------------------------------------------------------
 
  void fill(const std::tuple<Fields...> &init)
  {
    if constexpr (std::is_same_v<Layout, Layout_SoA>)
      fill_impl(init, std::index_sequence_for<Fields...>{});
    else
      store_.fill(init);
  }
 
  void swap(Multi_Field_Lattice &other) noexcept
  {
    using std::swap;
    swap(store_, other.store_);
    swap(extents_, other.extents_);
  }
 
  template <std::size_t I>
  void swap_field(Multi_Field_Lattice &other)
    requires std::is_same_v<Layout, Layout_SoA>
  {
    static_assert(I < field_count, "field index out of range");
    using std::swap;
    swap(std::get<I>(store_), std::get<I>(other.store_));
  }
 
private:
  // SoA helpers ---------------------------------------------------------
  template <std::size_t... I>
  void set_cell_impl(const coord_type &c,
                     const std::tuple<Fields...> &cell,
                     ca_mf_detail::index_seq<I...>)
  {
    ((std::get<I>(store_).set(c, std::get<I>(cell))), ...);
  }
 
  template <std::size_t... I>
  std::tuple<Fields...> at_cell_impl(const coord_type &c, ca_mf_detail::index_seq<I...>) const
  {
    return std::tuple<Fields...>{std::get<I>(store_).at(c)...};
  }
 
  template <std::size_t... I>
  void fill_impl(const std::tuple<Fields...> &init, ca_mf_detail::index_seq<I...>)
  {
    ((std::get<I>(store_).fill(std::get<I>(init))), ...);
  }
};
 
template <typename Layout, typename Boundary, std::size_t Rank, typename... Fields>
inline void swap(Multi_Field_Lattice<Layout, Boundary, Rank, Fields...> &a,
                 Multi_Field_Lattice<Layout, Boundary, Rank, Fields...> &b) noexcept
{
  a.swap(b);
}
 
template <typename L>
concept MultiFieldLatticeLike = requires {
  typename L::coord_type;
  typename L::extents_type;
  { L::field_count } -> std::convertible_to<std::size_t>;
  { L::rank } -> std::convertible_to<std::size_t>;
} and requires(const L &l, std::size_t d) {
  { l.dimension() } -> std::convertible_to<std::size_t>;
  { l.size(d) } -> std::convertible_to<std::size_t>;
};
 
}  // namespace CA
}  // namespace Aleph
 
#endif  // TPL_CA_MULTI_FIELD_LATTICE_H