llvm/libcxx/test/std/containers/views/mdspan/layout_right/required_span_size.pass.cpp

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20

// <mdspan>

// constexpr index_type required_span_size() const noexcept;
//
// Returns: extents().fwd-prod-of-extents(extents_type::rank()).


#include <mdspan>
#include <cassert>
#include <cstdint>
#include <span> // dynamic_extent

#include "test_macros.h"

template <class E>
constexpr void test_required_span_size(E e, typename E::index_type expected_size) {
  using M = std::layout_right::mapping<E>;
  const M m(e);

  ASSERT_NOEXCEPT(m.required_span_size());
  assert(m.required_span_size() == expected_size);
}

constexpr bool test() {
  constexpr size_t D = std::dynamic_extent;
  test_required_span_size(std::extents<int>(), 1);
  test_required_span_size(std::extents<unsigned, D>(0), 0);
  test_required_span_size(std::extents<unsigned, D>(1), 1);
  test_required_span_size(std::extents<unsigned, D>(7), 7);
  test_required_span_size(std::extents<unsigned, 7>(), 7);
  test_required_span_size(std::extents<unsigned, 7, 8>(), 56);
  test_required_span_size(std::extents<int64_t, D, 8, D, D>(7, 9, 10), 5040);
  test_required_span_size(std::extents<int64_t, 1, 8, D, D>(9, 10), 720);
  test_required_span_size(std::extents<int64_t, 1, 0, D, D>(9, 10), 0);
  return true;
}

int main(int, char**) {
  test();
  static_assert(test());
  return 0;
}