tpl_ca_neighborhood_test.cc

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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
 
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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*/
 
# include <array>
# include <cstdint>
# include <set>
# include <span>
# include <stdexcept>
 
# include <gtest/gtest.h>
 
# include <ca-traits.H>
# include <tpl_ca_concepts.H>
# include <tpl_ca_storage.H>
# include <tpl_ca_lattice.H>
# include <tpl_ca_neighborhood.H>
 
using namespace Aleph;
using namespace Aleph::CA;
 
// ---------------------------------------------------------------------------
// Compile-time concept conformance.
// ---------------------------------------------------------------------------
 
static_assert(NeighborhoodLike<Moore<2, 1>>);
static_assert(NeighborhoodLike<Moore<2, 2>>);
static_assert(NeighborhoodLike<Moore<3, 1>>);
static_assert(NeighborhoodLike<Von_Neumann<2, 1>>);
static_assert(NeighborhoodLike<Von_Neumann<3, 1>>);
static_assert(NeighborhoodLike<Hex_Neighborhood>);
static_assert(NeighborhoodLike<Triangular_Neighborhood>);
static_assert(NeighborhoodLike<Custom_Neighborhood<2, 4>>);
static_assert(Custom_Neighborhood<2, 3, 5>::radius_v == 5);
 
// ---------------------------------------------------------------------------
// Compile-time count checks.
// ---------------------------------------------------------------------------
 
static_assert(Moore<1, 1>::size_v == 2);
static_assert(Moore<1, 2>::size_v == 4);
static_assert(Moore<2, 1>::size_v == 8);
static_assert(Moore<2, 2>::size_v == 24);
static_assert(Moore<3, 1>::size_v == 26);
 
static_assert(Von_Neumann<1, 1>::size_v == 2);
static_assert(Von_Neumann<2, 1>::size_v == 4);
static_assert(Von_Neumann<2, 2>::size_v == 12);
static_assert(Von_Neumann<3, 1>::size_v == 6);
static_assert(Von_Neumann<3, 2>::size_v == 24);
 
static_assert(Hex_Neighborhood::size_v == 6);
static_assert(Triangular_Neighborhood::size_v == 3);
 
// ---------------------------------------------------------------------------
// Moore — every offset must be unique, non-zero, and inside the radius.
// ---------------------------------------------------------------------------
 
TEST(CAMoore, OffsetsAreUniqueNonZeroAndBounded)
{
  Moore<2, 1> nh;
  EXPECT_EQ(nh.size(), 8u);
  EXPECT_EQ(nh.radius(), 1u);
 
  std::set<std::pair<int, int>> seen;
  std::size_t calls = 0;
  nh.for_each_offset({ 0, 0 }, [&](const auto & o)
    {
      ++calls;
      EXPECT_FALSE(o[0] == 0 and o[1] == 0);
      EXPECT_GE(o[0], -1); EXPECT_LE(o[0], 1);
      EXPECT_GE(o[1], -1); EXPECT_LE(o[1], 1);
      seen.emplace(static_cast<int>(o[0]), static_cast<int>(o[1]));
    });
  EXPECT_EQ(calls, 8u);
  EXPECT_EQ(seen.size(), 8u);
}
 
TEST(CAMoore, R2In2DProduces24Offsets)
{
  Moore<2, 2> nh;
  std::size_t calls = 0;
  nh.for_each_offset({ 0, 0 }, [&](const auto & o) {
    ++calls;
    EXPECT_FALSE(o[0] == 0 and o[1] == 0);
    EXPECT_LE(std::max(std::abs((int)o[0]), std::abs((int)o[1])), 2);
  });
  EXPECT_EQ(calls, 24u);
}
 
// ---------------------------------------------------------------------------
// Von Neumann — offsets satisfy L1 ≤ R and ≥ 1.
// ---------------------------------------------------------------------------
 
TEST(CAVonNeumann, R1In2DGivesFourCardinalOffsets)
{
  Von_Neumann<2, 1> nh;
  EXPECT_EQ(nh.size(), 4u);
 
  std::set<std::pair<int, int>> seen;
  nh.for_each_offset({ 0, 0 }, [&](const auto & o) {
    seen.emplace(static_cast<int>(o[0]), static_cast<int>(o[1]));
  });
  EXPECT_EQ(seen.count({ -1,  0 }), 1u);
  EXPECT_EQ(seen.count({  1,  0 }), 1u);
  EXPECT_EQ(seen.count({  0, -1 }), 1u);
  EXPECT_EQ(seen.count({  0,  1 }), 1u);
}
 
TEST(CAVonNeumann, R2In2DOffsetsRespectL1Bound)
{
  Von_Neumann<2, 2> nh;
  std::size_t calls = 0;
  nh.for_each_offset({ 0, 0 }, [&](const auto & o) {
    ++calls;
    const int s = std::abs((int)o[0]) + std::abs((int)o[1]);
    EXPECT_GE(s, 1); EXPECT_LE(s, 2);
  });
  EXPECT_EQ(calls, 12u);
}
 
// ---------------------------------------------------------------------------
// Hex
// ---------------------------------------------------------------------------
 
TEST(CAHexNeighborhood, SixAxialOffsets)
{
  Hex_Neighborhood nh;
  EXPECT_EQ(nh.size(), 6u);
 
  std::set<std::pair<int, int>> seen;
  nh.for_each_offset({ 0, 0 }, [&](const auto & o) {
    seen.emplace(static_cast<int>(o[0]), static_cast<int>(o[1]));
  });
  EXPECT_EQ(seen.size(), 6u);
  EXPECT_EQ(seen.count({  1,  0 }), 1u);
  EXPECT_EQ(seen.count({ -1,  0 }), 1u);
  EXPECT_EQ(seen.count({  0,  1 }), 1u);
  EXPECT_EQ(seen.count({  0, -1 }), 1u);
  EXPECT_EQ(seen.count({  1, -1 }), 1u);
  EXPECT_EQ(seen.count({ -1,  1 }), 1u);
}
 
// ---------------------------------------------------------------------------
// Triangular — third offset is parity-dependent.
// ---------------------------------------------------------------------------
 
TEST(CATriangularNeighborhood, ParityDependentThirdOffset)
{
  Triangular_Neighborhood nh;
  EXPECT_EQ(nh.size(), 3u);
 
  // Even parity (i+j even) → third offset is (1, 0).
  std::set<std::pair<int, int>> seen_even;
  nh.for_each_offset({ 0, 0 }, [&](const auto & o) {
    seen_even.emplace(static_cast<int>(o[0]), static_cast<int>(o[1]));
  });
  EXPECT_EQ(seen_even.count({  0, -1 }), 1u);
  EXPECT_EQ(seen_even.count({  0,  1 }), 1u);
  EXPECT_EQ(seen_even.count({  1,  0 }), 1u);
 
  // Odd parity → third offset is (-1, 0).
  std::set<std::pair<int, int>> seen_odd;
  nh.for_each_offset({ 0, 1 }, [&](const auto & o) {
    seen_odd.emplace(static_cast<int>(o[0]), static_cast<int>(o[1]));
  });
  EXPECT_EQ(seen_odd.count({  0, -1 }), 1u);
  EXPECT_EQ(seen_odd.count({  0,  1 }), 1u);
  EXPECT_EQ(seen_odd.count({ -1,  0 }), 1u);
}
 
// ---------------------------------------------------------------------------
// Custom
// ---------------------------------------------------------------------------
 
TEST(CACustomNeighborhood, EnumeratesProvidedOffsets)
{
  Custom_Neighborhood<2, 3> nh(std::array<Offset_Vec<2>, 3>{ Offset_Vec<2>{ 2, 0 },
                                                             Offset_Vec<2>{ 0, 2 },
                                                             Offset_Vec<2>{ -3, 1 } });
  EXPECT_EQ(nh.size(), 3u);
  EXPECT_EQ(nh.radius(), 3u);  // largest |component| is 3
 
  std::vector<std::pair<int, int>> seen;
  nh.for_each_offset({ 0, 0 }, [&](const auto & o) {
    seen.emplace_back(static_cast<int>(o[0]), static_cast<int>(o[1]));
  });
  ASSERT_EQ(seen.size(), 3u);
  EXPECT_EQ(seen[0].first, 2);  EXPECT_EQ(seen[0].second, 0);
  EXPECT_EQ(seen[1].first, 0);  EXPECT_EQ(seen[1].second, 2);
  EXPECT_EQ(seen[2].first, -3); EXPECT_EQ(seen[2].second, 1);
}
 
// ---------------------------------------------------------------------------
// gather_neighbors — boundary policy is honoured via at_safe.
// ---------------------------------------------------------------------------
 
TEST(CAGatherNeighbors, MooreOnToroidalLattice)
{
  Lattice<Dense_Cell_Storage<int, 2>, ToroidalBoundary> lat({ 3, 3 }, 0);
  for (ca_index_t i = 0; i < 3; ++i)
    for (ca_index_t j = 0; j < 3; ++j)
      lat.set({ i, j }, static_cast<int>(i * 10 + j));
 
  Moore<2, 1> nh;
  std::array<int, Moore<2, 1>::size_v> buf { };
  gather_neighbors(nh, lat, Coord_Vec<2>{ 0, 0 },
                   std::span<int>(buf.data(), buf.size()));
 
  // Sum of all 8 neighbours of (0,0) under toroidal wrap on a 3x3
  // lattice equals (sum of all cells) - cell(0,0). All cells: 0+1+2+
  // 10+11+12+20+21+22 = 99. Minus cell(0,0) = 99.
  int total = 0;
  for (int v : buf) total += v;
  EXPECT_EQ(total, 99);
}
 
TEST(CAGatherNeighbors, MooreOnOpenLatticeReadsZeroOutsideBorders)
{
  Lattice<Dense_Cell_Storage<int, 2>, OpenBoundary> lat({ 3, 3 }, 1);
  Moore<2, 1> nh;
  std::array<int, Moore<2, 1>::size_v> buf { };
  gather_neighbors(nh, lat, Coord_Vec<2>{ 0, 0 },
                   std::span<int>(buf.data(), buf.size()));
 
  // (0,0) has only 3 in-range neighbours: (0,1), (1,0), (1,1). The
  // remaining 5 read as 0 (open boundary).
  int alive = 0;
  for (int v : buf) if (v != 0) ++alive;
  EXPECT_EQ(alive, 3);
}
 
TEST(CAGatherNeighbors, ThrowsWhenOutputSpanIsTooSmall)
{
  Lattice<Dense_Cell_Storage<int, 2>, OpenBoundary> lat({ 3, 3 }, 1);
  Moore<2, 1> nh;
  std::array<int, 2> buf { };
  EXPECT_THROW(gather_neighbors(nh, lat, Coord_Vec<2>{ 0, 0 },
                                std::span<int>(buf.data(), buf.size())),
               std::length_error);
}