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// namespace std {
14// template<class Extents>
15// class layout_stride::mapping {
16//
17// ...
18// static constexpr bool is_always_unique() noexcept { return true; }
19// static constexpr bool is_always_exhaustive() noexcept { return false; }
20// static constexpr bool is_always_strided() noexcept { return true; }
21//
22// static constexpr bool is_unique() noexcept { return true; }
23// static constexpr bool is_exhaustive() noexcept;
24// static constexpr bool is_strided() noexcept { return true; }
25// ...
26// };
27// }
28//
29//
30// layout_stride::mapping<E> is a trivially copyable type that models regular for each E.
31//
32// constexpr bool is_exhaustive() const noexcept;
33//
34// Returns:
35// - true if rank_ is 0.
36// - Otherwise, true if there is a permutation P of the integers in the range [0, rank_) such that
37// stride(p0) equals 1, and stride(pi) equals stride(pi_1) * extents().extent(pi_1) for i in the
38// range [1, rank_), where pi is the ith element of P.
39// - Otherwise, false.
40
41#include <array>
42#include <cassert>
43#include <concepts>
44#include <cstddef>
45#include <mdspan>
46#include <type_traits>
47
48#include "test_macros.h"
49
50template <class E>
51constexpr void
52test_layout_mapping_stride(E ext, std::array<typename E::index_type, E::rank()> strides, bool exhaustive) {
53 using M = std::layout_stride::mapping<E>;
54 M m(ext, strides);
55 const M c_m = m;
56 assert(m.strides() == strides);
57 assert(c_m.strides() == strides);
58 assert(m.extents() == ext);
59 assert(c_m.extents() == ext);
60 assert(M::is_unique() == true);
61 assert(m.is_exhaustive() == exhaustive);
62 assert(c_m.is_exhaustive() == exhaustive);
63 assert(M::is_strided() == true);
64 assert(M::is_always_unique() == true);
65 assert(M::is_always_exhaustive() == false);
66 assert(M::is_always_strided() == true);
67
68 ASSERT_NOEXCEPT(m.strides());
69 ASSERT_NOEXCEPT(c_m.strides());
70 ASSERT_NOEXCEPT(m.extents());
71 ASSERT_NOEXCEPT(c_m.extents());
72 ASSERT_NOEXCEPT(M::is_unique());
73 ASSERT_NOEXCEPT(m.is_exhaustive());
74 ASSERT_NOEXCEPT(c_m.is_exhaustive());
75 ASSERT_NOEXCEPT(M::is_strided());
76 ASSERT_NOEXCEPT(M::is_always_unique());
77 ASSERT_NOEXCEPT(M::is_always_exhaustive());
78 ASSERT_NOEXCEPT(M::is_always_strided());
79
80 for (typename E::rank_type r = 0; r < E::rank(); r++) {
81 assert(m.stride(r) == strides[r]);
82 assert(c_m.stride(r) == strides[r]);
83 ASSERT_NOEXCEPT(m.stride(r));
84 ASSERT_NOEXCEPT(c_m.stride(r));
85 }
86
87 typename E::index_type expected_size = 1;
88 for (typename E::rank_type r = 0; r < E::rank(); r++) {
89 if (ext.extent(r) == 0) {
90 expected_size = 0;
91 break;
92 }
93 expected_size += (ext.extent(r) - 1) * static_cast<typename E::index_type>(strides[r]);
94 }
95 assert(m.required_span_size() == expected_size);
96 assert(c_m.required_span_size() == expected_size);
97 ASSERT_NOEXCEPT(m.required_span_size());
98 ASSERT_NOEXCEPT(c_m.required_span_size());
99
100 static_assert(std::is_trivially_copyable_v<M>);
101 static_assert(std::regular<M>);
102}
103
104constexpr bool test() {
105 constexpr size_t D = std::dynamic_extent;
106 test_layout_mapping_stride(std::extents<int>(), std::array<int, 0>{}, true);
107 test_layout_mapping_stride(std::extents<signed char, 4, 5>(), std::array<signed char, 2>{1, 4}, true);
108 test_layout_mapping_stride(std::extents<signed char, 4, 5>(), std::array<signed char, 2>{1, 5}, false);
109 test_layout_mapping_stride(std::extents<unsigned, D, 4>(7), std::array<unsigned, 2>{20, 2}, false);
110 test_layout_mapping_stride(std::extents<size_t, D, D, D, D>(3, 3, 3, 3), std::array<size_t, 4>{3, 1, 9, 27}, true);
111 return true;
112}
113
114int main(int, char**) {
115 test();
116 static_assert(test());
117 return 0;
118}
119

source code of libcxx/test/std/containers/views/mdspan/layout_stride/properties.pass.cpp