tpl_ca_concepts.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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#ifndef TPL_CA_CONCEPTS_H
#define TPL_CA_CONCEPTS_H
 
#include <concepts>
#include <cstddef>
#include <tuple>
#include <type_traits>
#include <utility>
 
#include <ca-traits.H>
 
namespace Aleph {
namespace CA {
 
template <typename T>
concept CellState = std::regular<T>;
 
template <typename C, std::size_t N>
concept Coord = std::regular<C> and requires(C c, std::size_t i) {
  { c[i] } -> std::convertible_to<ca_index_t>;
  { C{}.size() } -> std::convertible_to<std::size_t>;
} and (std::tuple_size<C>::value == N);
 
template <typename L>
concept LatticeLike = requires {
  typename L::state_type;
  typename L::coord_type;
} and CellState<typename L::state_type> and requires(L &lat, const L &clat, const typename L::coord_type &c, const typename L::state_type &v, std::size_t d) {
  { clat.dimension() } -> std::convertible_to<std::size_t>;
  { clat.size(d) } -> std::convertible_to<std::size_t>;
  { clat.at(c) } -> std::convertible_to<typename L::state_type>;
  { lat.set(c, v) };
};
 
template <typename H>
concept NeighborhoodLike =
  requires {
    typename H::coord_type;
    { H::rank_v } -> std::convertible_to<std::size_t>;
    { H::size_v } -> std::convertible_to<std::size_t>;
  }
  and requires(const H &h, const typename H::coord_type &center) {
    { h.radius() } -> std::convertible_to<std::size_t>;
    { h.size()   } -> std::convertible_to<std::size_t>;
    h.for_each_offset(center, [](const auto &) {});
  };
 
template <typename R, typename L>
concept BasicRuleLike
  = LatticeLike<L>
and requires(const R &r, const typename L::state_type &s, Neighbor_View<typename L::state_type> v) {
      { r(s, v) } -> std::convertible_to<typename L::state_type>;
    };
 
template <typename R, typename L>
concept ContextualRuleLike
  = LatticeLike<L>
and requires(const R &r, const typename L::state_type &s,
             Neighbor_View<typename L::state_type> v,
             const Cell_Context<L::rank> &ctx) {
      { r(s, v, ctx) } -> std::convertible_to<typename L::state_type>;
    };
 
template <typename R, typename L>
concept RuleLike = BasicRuleLike<R, L> or ContextualRuleLike<R, L>;
 
template <typename Rule, typename State, std::size_t Rank>
[[nodiscard]] inline State apply_rule(const Rule &r,
                                      const State &s,
                                      Neighbor_View<State> v,
                                      const Cell_Context<Rank> &ctx)
{
  if constexpr (requires { r(s, v, ctx); })
    return r(s, v, ctx);
  else
    return r(s, v);
}
 
template <typename L>
concept HasRefreshHalo = requires(L &l) { l.refresh_halo(); };
 
// Forward declarations only: HexRenderable/TriRenderable below name these
// types in non-dependent expressions. std::declval<T>() (unlike `T{}`)
// never constructs a T, so it only needs T declared here, not complete;
// both are complete by the time the concepts are actually evaluated, at
// their use sites in ca-svg.H/ca-tikz.H, which include the full
// tpl_ca_hex_lattice.H/tpl_ca_triangular_lattice.H definitions. Including
// those headers here instead would be circular (they include this one).
struct Hex_Axial;
struct Tri_Coord;
 
template <typename Lattice>
concept HexRenderable = requires(const Lattice &lat) {
  lat.rows();
  lat.cols();
  lat.at_axial(std::declval<Hex_Axial>());
};
 
template <typename Lattice>
concept TriRenderable = requires(const Lattice &lat) {
  lat.rows();
  lat.cols();
  lat.at_tri(std::declval<Tri_Coord>());
};
 
}  // namespace CA
}  // namespace Aleph
 
#endif  // TPL_CA_CONCEPTS_H