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 <mdspan>
42#include <type_traits>
43#include <concepts>
44#include <cassert>
45
46#include "test_macros.h"
47
48template <class E>
49constexpr void
50test_layout_mapping_stride(E ext, std::array<typename E::index_type, E::rank()> strides, bool exhaustive) {
51 using M = std::layout_stride::mapping<E>;
52 M m(ext, strides);
53 const M c_m = m;
54 assert(m.strides() == strides);
55 assert(c_m.strides() == strides);
56 assert(m.extents() == ext);
57 assert(c_m.extents() == ext);
58 assert(M::is_unique() == true);
59 assert(m.is_exhaustive() == exhaustive);
60 assert(c_m.is_exhaustive() == exhaustive);
61 assert(M::is_strided() == true);
62 assert(M::is_always_unique() == true);
63 assert(M::is_always_exhaustive() == false);
64 assert(M::is_always_strided() == true);
65
66 ASSERT_NOEXCEPT(m.strides());
67 ASSERT_NOEXCEPT(c_m.strides());
68 ASSERT_NOEXCEPT(m.extents());
69 ASSERT_NOEXCEPT(c_m.extents());
70 ASSERT_NOEXCEPT(M::is_unique());
71 ASSERT_NOEXCEPT(m.is_exhaustive());
72 ASSERT_NOEXCEPT(c_m.is_exhaustive());
73 ASSERT_NOEXCEPT(M::is_strided());
74 ASSERT_NOEXCEPT(M::is_always_unique());
75 ASSERT_NOEXCEPT(M::is_always_exhaustive());
76 ASSERT_NOEXCEPT(M::is_always_strided());
77
78 for (typename E::rank_type r = 0; r < E::rank(); r++) {
79 assert(m.stride(r) == strides[r]);
80 assert(c_m.stride(r) == strides[r]);
81 ASSERT_NOEXCEPT(m.stride(r));
82 ASSERT_NOEXCEPT(c_m.stride(r));
83 }
84
85 typename E::index_type expected_size = 1;
86 for (typename E::rank_type r = 0; r < E::rank(); r++) {
87 if (ext.extent(r) == 0) {
88 expected_size = 0;
89 break;
90 }
91 expected_size += (ext.extent(r) - 1) * static_cast<typename E::index_type>(strides[r]);
92 }
93 assert(m.required_span_size() == expected_size);
94 assert(c_m.required_span_size() == expected_size);
95 ASSERT_NOEXCEPT(m.required_span_size());
96 ASSERT_NOEXCEPT(c_m.required_span_size());
97
98 static_assert(std::is_trivially_copyable_v<M>);
99 static_assert(std::regular<M>);
100}
101
102constexpr bool test() {
103 constexpr size_t D = std::dynamic_extent;
104 test_layout_mapping_stride(std::extents<int>(), std::array<int, 0>{}, true);
105 test_layout_mapping_stride(std::extents<signed char, 4, 5>(), std::array<signed char, 2>{1, 4}, true);
106 test_layout_mapping_stride(std::extents<signed char, 4, 5>(), std::array<signed char, 2>{1, 5}, false);
107 test_layout_mapping_stride(std::extents<unsigned, D, 4>(7), std::array<unsigned, 2>{20, 2}, false);
108 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);
109 return true;
110}
111
112int main(int, char**) {
113 test();
114 static_assert(test());
115 return 0;
116}
117

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