libcxx/test/std/containers/views/mdspan/layout_stride/ctor.default.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
  10
  11 // <mdspan>
  12
  13 // Test default construction:
  14 //
  15 // constexpr mapping() noexcept;
  16 //
  17 //
  18 // Preconditions: layout_right::mapping<extents_type>().required_span_size() is representable as a value of type index_type ([basic.fundamental]).
  19 //
  20 // Effects: Direct-non-list-initializes extents_ with extents_type(), and for all d in the range [0, rank_),
  21 //          direct-non-list-initializes strides_[d] with layout_right::mapping<extents_type>().stride(d).
  22
  23 #include <cassert>
  24 #include <cstddef>
  25 #include <cstdint>
  26 #include <mdspan>
  27 #include <span> // dynamic_extent
  28
  29 #include "test_macros.h"
  30
  31 template <class E>
  32 constexpr void test_construction() {
  33   using M = std::layout_stride::mapping<E>;
  34   ASSERT_NOEXCEPT(M{});
  35   M m;
  36   E e;
  37
  38   // check correct extents are returned
  39   ASSERT_NOEXCEPT(m.extents());
  40   assert(m.extents() == e);
  41
  42   // check required_span_size()
  43   typename E::index_type expected_size = 1;
  44   for (typename E::rank_type r = 0; r < E::rank(); r++)
  45     expected_size *= e.extent(r);
  46   assert(m.required_span_size() == expected_size);
  47
  48   // check strides: node stride function is constrained on rank>0, e.extent(r) is not
  49   auto strides = m.strides();
  50   ASSERT_NOEXCEPT(m.strides());
  51   if constexpr (E::rank() > 0) {
  52     std::layout_right::mapping<E> m_right;
  53     for (typename E::rank_type r = 0; r < E::rank(); r++) {
  54       assert(m.stride(r) == m_right.stride(r));
  55       assert(strides[r] == m.stride(r));
  56     }
  57   }
  58 }
  59
  60 constexpr bool test() {
  61   constexpr size_t D = std::dynamic_extent;
  62   test_construction<std::extents<int>>();
  63   test_construction<std::extents<unsigned, D>>();
  64   test_construction<std::extents<unsigned, 7>>();
  65   test_construction<std::extents<unsigned, 0>>();
  66   test_construction<std::extents<unsigned, 7, 8>>();
  67   test_construction<std::extents<int64_t, D, 8, D, D>>();
  68   return true;
  69 }
  70
  71 int main(int, char**) {
  72   test();
  73   static_assert(test());
  74   return 0;
  75 }