ah_mdspan_test.cc

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/*
                          Aleph_w
 
  Data structures & Algorithms
  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
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#include <array>
#include <stdexcept>
#include <type_traits>
#include <vector>
 
#include <gtest/gtest.h>
 
#include <ah-mdspan.H>
 
using Aleph::dextents;
using Aleph::dynamic_extent;
using Aleph::extents;
using Aleph::layout_left;
using Aleph::layout_right;
using Aleph::mdspan;
 
// Compile-time regression: operator()/at() must reject a wrong number of
// indices for the view's rank instead of silently reading past a local
// array (a real out-of-bounds stack read was reproduced before this
// constraint existed — see the PR review discussion). A rank-2 view must
// accept exactly 2 indices, not 1 and not 3.
using Rank2 = mdspan<int, dextents<size_t, 2>>;
 
// A bare top-level `requires(Rank2 m) { m(1); }` would NOT reliably detect
// this: once `Rank2` is a fully concrete (non-dependent) type, an unsatisfied
// call is a plain "no matching function" error, not a substitution failure
// in the immediate context of a template parameter -- so it is not silently
// absorbed. Wrapping the check in a genuine template (a concept) restores
// the SFINAE-friendly behavior actually needed here.
template <class M, class... Args>
concept CanCall = requires(M m, Args... args) { m(args...); };
template <class M, class... Args>
concept CanCallAt = requires(M m, Args... args) { m.at(args...); };
 
static_assert(CanCall<Rank2, int, int>);
static_assert(not CanCall<Rank2, int>);
static_assert(not CanCall<Rank2, int, int, int>);
static_assert(CanCallAt<Rank2, int, int>);
static_assert(not CanCallAt<Rank2, int>);
static_assert(not CanCallAt<Rank2, int, int, int>);
 
TEST(AhMdspan, DetectionMacroIsDefined)
{
  // Must always be defined to 0 or 1, regardless of -std.
  constexpr int v = ALEPH_HAS_STD_MDSPAN;
  EXPECT_TRUE(v == 0 or v == 1);
}
 
TEST(AhMdspan, DextentsRankAndRankDynamic)
{
  using Ext = dextents<size_t, 3>;
  static_assert(Ext::rank() == 3);
  static_assert(Ext::rank_dynamic() == 3);
  Ext e(2, 3, 4);
  EXPECT_EQ(e.extent(0), 2u);
  EXPECT_EQ(e.extent(1), 3u);
  EXPECT_EQ(e.extent(2), 4u);
}
 
TEST(AhMdspan, MixedStaticAndDynamicExtents)
{
  // Axis 0 dynamic, axis 1 fixed to 4.
  using Ext = extents<size_t, dynamic_extent, 4>;
  static_assert(Ext::rank() == 2);
  static_assert(Ext::rank_dynamic() == 1);
  static_assert(Ext::static_extent(1) == 4);
  static_assert(Ext::static_extent(0) == dynamic_extent);
 
  Ext e(7);  // only the one dynamic axis needs a value
  EXPECT_EQ(e.extent(0), 7u);
  EXPECT_EQ(e.extent(1), 4u);
}
 
TEST(AhMdspan, ExtentsFromArray)
{
  std::array<size_t, 2> shape{3, 5};
  dextents<size_t, 2> e(shape);
  EXPECT_EQ(e.extent(0), 3u);
  EXPECT_EQ(e.extent(1), 5u);
}
 
TEST(AhMdspan, ExtentsEquality)
{
  dextents<size_t, 2> a(2, 3);
  dextents<size_t, 2> b(2, 3);
  dextents<size_t, 2> c(3, 2);
  EXPECT_TRUE(a == b);
  EXPECT_FALSE(a == c);
}
 
TEST(AhMdspan, BasicConstructionAndShape)
{
  std::vector<int> buf(2 * 3, 0);
  mdspan<int, dextents<size_t, 2>> m(buf.data(), 2, 3);
 
  EXPECT_EQ(m.rank(), 2u);
  EXPECT_EQ(m.extent(0), 2u);
  EXPECT_EQ(m.extent(1), 3u);
  EXPECT_EQ(m.size(), 6u);
  EXPECT_FALSE(m.empty());
  EXPECT_EQ(m.data_handle(), buf.data());
}
 
TEST(AhMdspan, OperatorRequiresExactRankArguments)
{
  std::vector<int> buf(6, 0);
  mdspan<int, dextents<size_t, 2>> m(buf.data(), 2, 3);
  
  // Valid call: 2 indices for rank-2 span
  static_assert(std::is_invocable_v<decltype(m), int, int>);
  
  // Invalid calls: wrong arity
  static_assert(not std::is_invocable_v<decltype(m), int>);
  static_assert(not std::is_invocable_v<decltype(m), int, int, int>);
}
 
TEST(AhMdspan, ConstructFromArrayOfDynamicExtents)
{
  std::vector<int> buf(6, 0);
  std::array<size_t, 2> shape{2, 3};
  mdspan<int, dextents<size_t, 2>> m(buf.data(), shape);
  EXPECT_EQ(m.extent(0), 2u);
  EXPECT_EQ(m.extent(1), 3u);
}
 
TEST(AhMdspan, RowMajorIsDefaultAndMatchesFlatBufferOrder)
{
  // layout_right (row-major): the LAST axis varies fastest, i.e. m(i, j)
  // maps to buf[i * ncols + j] -- exactly Aleph's own Array/C convention.
  std::vector<int> buf(2 * 3, 0);
  mdspan<int, dextents<size_t, 2>> m(buf.data(), 2, 3);
 
  int next = 0;
  for (size_t i = 0; i < m.extent(0); ++i)
    for (size_t j = 0; j < m.extent(1); ++j)
      m(i, j) = next++;
 
  EXPECT_EQ(buf, (std::vector<int>{0, 1, 2, 3, 4, 5}));
}
 
TEST(AhMdspan, LayoutLeftIsColumnMajor)
{
  // layout_left (column-major): the FIRST axis varies fastest.
  std::vector<int> buf(2 * 3, 0);
  mdspan<int, dextents<size_t, 2>, layout_left> m(buf.data(), 2, 3);
 
  int next = 0;
  for (size_t j = 0; j < m.extent(1); ++j)
    for (size_t i = 0; i < m.extent(0); ++i)
      m(i, j) = next++;
 
  EXPECT_EQ(buf, (std::vector<int>{0, 1, 2, 3, 4, 5}));
}
 
TEST(AhMdspan, WriteThroughViewIsVisibleThroughBuffer)
{
  std::vector<double> buf(4, 0.0);
  mdspan<double, dextents<size_t, 2>> m(buf.data(), 2, 2);
  m(0, 0) = 1.0;
  m(0, 1) = 2.0;
  m(1, 0) = 3.0;
  m(1, 1) = 4.0;
  EXPECT_EQ(buf, (std::vector<double>{1.0, 2.0, 3.0, 4.0}));
}
 
TEST(AhMdspan, ReadOnlyViewOverConstElement)
{
  const std::vector<int> buf{9, 8, 7, 6};
  mdspan<const int, dextents<size_t, 1>> m(buf.data(), 4);
  EXPECT_EQ(m(0), 9);
  EXPECT_EQ(m(2), 7);
  static_assert(std::is_const_v<std::remove_reference_t<decltype(m(0))>>);
}
 
TEST(AhMdspan, AtThrowsOnOutOfRangeIndex)
{
  std::vector<int> buf(6, 0);
  mdspan<int, dextents<size_t, 2>> m(buf.data(), 2, 3);
  EXPECT_NO_THROW((void) m.at(1, 2));
  EXPECT_THROW((void) m.at(2, 0), std::out_of_range);
  EXPECT_THROW((void) m.at(0, 3), std::out_of_range);
}
 
TEST(AhMdspan, OneDimensionalView)
{
  std::vector<int> buf{10, 20, 30};
  mdspan<int, dextents<size_t, 1>> m(buf.data(), 3);
  EXPECT_EQ(m.rank(), 1u);
  EXPECT_EQ(m(0), 10);
  EXPECT_EQ(m(2), 30);
}
 
TEST(AhMdspan, ThreeDimensionalRowMajorRoundTrip)
{
  std::vector<int> buf(2 * 2 * 2, -1);
  mdspan<int, dextents<size_t, 3>> m(buf.data(), 2, 2, 2);
 
  int next = 0;
  for (size_t i = 0; i < 2; ++i)
    for (size_t j = 0; j < 2; ++j)
      for (size_t k = 0; k < 2; ++k)
        m(i, j, k) = next++;
 
  for (int v : buf)
    EXPECT_NE(v, -1);
  EXPECT_EQ(m(1, 1, 1), 7);
  EXPECT_EQ(buf.back(), 7);
}
 
TEST(AhMdspan, DefaultConstructedIsEmptyWithNullData)
{
  mdspan<int, dextents<size_t, 1>> m;
  EXPECT_EQ(m.data_handle(), nullptr);
  EXPECT_TRUE(m.empty());
  EXPECT_EQ(m.size(), 0u);
}
 
TEST(AhMdspan, MultipleIndependentViewsOverSameBufferDoNotInterfere)
{
  std::vector<int> buf(4, 0);
  mdspan<int, dextents<size_t, 2>> m1(buf.data(), 2, 2);
  mdspan<int, dextents<size_t, 2>> m2(buf.data(), 2, 2);
  m1(0, 0) = 42;
  EXPECT_EQ(m2(0, 0), 42);  // same underlying buffer: aliasing is intentional
}
 
TEST(AhMdspan, MutableViewConvertsImplicitlyToConstView)
{
  // Mirrors T* -> const T* implicit conversion.
  int buf[4] = {1, 2, 3, 4};
  mdspan<int, dextents<size_t, 2>> m(buf, 2, 2);
 
  auto reader = [](mdspan<const int, dextents<size_t, 2>> v) { return v(1, 1); };
  EXPECT_EQ(reader(m), 4);
}