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// template<class StridedLayoutMapping>
14// constexpr explicit(see below)
15// mapping(const StridedLayoutMapping& other) noexcept;
16//
17// Constraints:
18// - layout-mapping-alike<StridedLayoutMapping> is satisfied.
19// - is_constructible_v<extents_type, typename StridedLayoutMapping::extents_type> is true.
20// - StridedLayoutMapping::is_always_unique() is true.
21// - StridedLayoutMapping::is_always_strided() is true.
22//
23// Preconditions:
24// - StridedLayoutMapping meets the layout mapping requirements ([mdspan.layout.policy.reqmts]),
25// - other.stride(r) > 0 is true for every rank index r of extents(),
26// - other.required_span_size() is representable as a value of type index_type ([basic.fundamental]), and
27// - OFFSET(other) == 0 is true.
28//
29// Effects: Direct-non-list-initializes extents_ with other.extents(), and for all d in the range [0, rank_),
30// direct-non-list-initializes strides_[d] with other.stride(d).
31//
32// Remarks: The expression inside explicit is equivalent to:
33// - !(is_convertible_v<typename StridedLayoutMapping::extents_type, extents_type> &&
34// (is-mapping-of<layout_left, LayoutStrideMapping> ||
35// is-mapping-of<layout_right, LayoutStrideMapping> ||
36// is-mapping-of<layout_stride, LayoutStrideMapping>))
37
38#include <mdspan>
39#include <cassert>
40#include <limits>
41#include <type_traits>
42
43#include "test_macros.h"
44
45#include "../CustomTestLayouts.h"
46
47template <bool implicit, class FromL, class ToE, class FromE>
48constexpr void test_conversion(FromE src_exts) {
49 using To = std::layout_stride::mapping<ToE>;
50 using From = typename FromL::template mapping<FromE>;
51
52 From src([&]() {
53 if constexpr (std::is_same_v<FromL, std::layout_stride>) {
54 // just construct some strides which aren't layout_left/layout_right
55 std::array<size_t, FromE::rank()> strides;
56 size_t stride = 2;
57 for (size_t r = 0; r < FromE::rank(); r++) {
58 strides[r] = stride;
59 stride *= src_exts.extent(r);
60 }
61 return From(src_exts, strides);
62 } else {
63 return From(src_exts);
64 }
65 }());
66
67 ASSERT_NOEXCEPT(To(src));
68 To dest(src);
69 assert(dest == src);
70
71 if constexpr (implicit) {
72 To dest_implicit = src;
73 assert(dest_implicit == src);
74 } else {
75 assert((!std::is_convertible_v<From, To>));
76 }
77}
78
79template <class FromL, class T1, class T2>
80constexpr void test_conversion() {
81 constexpr size_t D = std::dynamic_extent;
82 constexpr bool idx_convertible =
83 static_cast<size_t>(std::numeric_limits<T1>::max()) >= static_cast<size_t>(std::numeric_limits<T2>::max());
84 constexpr bool l_convertible =
85 std::is_same_v<FromL, std::layout_right> || std::is_same_v<FromL, std::layout_left> ||
86 std::is_same_v<FromL, std::layout_stride>;
87 constexpr bool idx_l_convertible = idx_convertible && l_convertible;
88
89 // clang-format off
90 // adding extents convertibility expectation
91 test_conversion<idx_l_convertible && true, FromL, std::extents<T1>>(std::extents<T2>());
92 test_conversion<idx_l_convertible && true, FromL, std::extents<T1, D>>(std::extents<T2, D>(0));
93 test_conversion<idx_l_convertible && true, FromL, std::extents<T1, D>>(std::extents<T2, D>(5));
94 test_conversion<idx_l_convertible && false, FromL, std::extents<T1, 5>>(std::extents<T2, D>(5));
95 test_conversion<idx_l_convertible && true, FromL, std::extents<T1, 5>>(std::extents<T2, 5>());
96 test_conversion<idx_l_convertible && false, FromL, std::extents<T1, 5, D>>(std::extents<T2, D, D>(5, 5));
97 test_conversion<idx_l_convertible && true, FromL, std::extents<T1, D, D>>(std::extents<T2, D, D>(5, 5));
98 test_conversion<idx_l_convertible && true, FromL, std::extents<T1, D, D>>(std::extents<T2, D, 7>(5));
99 test_conversion<idx_l_convertible && true, FromL, std::extents<T1, 5, 7>>(std::extents<T2, 5, 7>());
100 test_conversion<idx_l_convertible && false, FromL, std::extents<T1, 5, D, 8, D, D>>(std::extents<T2, D, D, 8, 9, 1>(5, 7));
101 test_conversion<idx_l_convertible && true, FromL, std::extents<T1, D, D, D, D, D>>(
102 std::extents<T2, D, D, D, D, D>(5, 7, 8, 9, 1));
103 test_conversion<idx_l_convertible && true, FromL, std::extents<T1, D, D, 8, 9, D>>(std::extents<T2, D, 7, 8, 9, 1>(5));
104 test_conversion<idx_l_convertible && true, FromL, std::extents<T1, 5, 7, 8, 9, 1>>(std::extents<T2, 5, 7, 8, 9, 1>());
105 // clang-format on
106}
107
108template <class IdxT, size_t... Extents>
109using ToM = std::layout_stride::mapping<std::extents<IdxT, Extents...>>;
110
111template <class FromL, class IdxT, size_t... Extents>
112using FromM = typename FromL::template mapping<std::extents<IdxT, Extents...>>;
113
114template <class FromL>
115constexpr void test_no_implicit_conversion() {
116 constexpr size_t D = std::dynamic_extent;
117
118 // Sanity check that one static to dynamic conversion works
119 static_assert(std::is_constructible_v<ToM<int, D>, FromM<FromL, int, 5>>);
120 static_assert(std::is_convertible_v<FromM<FromL, int, 5>, ToM<int, D>>);
121
122 // Check that dynamic to static conversion only works explicitly
123 static_assert(std::is_constructible_v<ToM<int, 5>, FromM<FromL, int, D>>);
124 static_assert(!std::is_convertible_v<FromM<FromL, int, D>, ToM<int, 5>>);
125
126 // Sanity check that one static to dynamic conversion works
127 static_assert(std::is_constructible_v<ToM<int, D, 7>, FromM<FromL, int, 5, 7>>);
128 static_assert(std::is_convertible_v<FromM<FromL, int, 5, 7>, ToM<int, D, 7>>);
129
130 // Check that dynamic to static conversion only works explicitly
131 static_assert(std::is_constructible_v<ToM<int, 5, 7>, FromM<FromL, int, D, 7>>);
132 static_assert(!std::is_convertible_v<FromM<FromL, int, D, 7>, ToM<int, 5, 7>>);
133
134 // Sanity check that smaller index_type to larger index_type conversion works
135 static_assert(std::is_constructible_v<ToM<size_t, 5>, FromM<FromL, int, 5>>);
136 static_assert(std::is_convertible_v<FromM<FromL, int, 5>, ToM<size_t, 5>>);
137
138 // Check that larger index_type to smaller index_type conversion works explicitly only
139 static_assert(std::is_constructible_v<ToM<int, 5>, FromM<FromL, size_t, 5>>);
140 static_assert(!std::is_convertible_v<FromM<FromL, size_t, 5>, ToM<int, 5>>);
141}
142
143template <class FromL>
144constexpr void test_rank_mismatch() {
145 constexpr size_t D = std::dynamic_extent;
146
147 static_assert(!std::is_constructible_v<ToM<int, D>, FromM<FromL, int>>);
148 static_assert(!std::is_constructible_v<ToM<int>, FromM<FromL, int, D, D>>);
149 static_assert(!std::is_constructible_v<ToM<int, D>, FromM<FromL, int, D, D>>);
150 static_assert(!std::is_constructible_v<ToM<int, D, D, D>, FromM<FromL, int, D, D>>);
151}
152
153template <class FromL>
154constexpr void test_static_extent_mismatch() {
155 constexpr size_t D = std::dynamic_extent;
156
157 static_assert(!std::is_constructible_v<ToM<int, D, 5>, FromM<FromL, int, D, 4>>);
158 static_assert(!std::is_constructible_v<ToM<int, 5>, FromM<FromL, int, 4>>);
159 static_assert(!std::is_constructible_v<ToM<int, 5, D>, FromM<FromL, int, 4, D>>);
160}
161
162template <class FromL>
163constexpr void test_layout() {
164 test_conversion<FromL, int, int>();
165 test_conversion<FromL, int, size_t>();
166 test_conversion<FromL, size_t, int>();
167 test_conversion<FromL, size_t, long>();
168 // the implicit convertibility test doesn't apply to non std::layouts
169 if constexpr (!std::is_same_v<FromL, always_convertible_layout>)
170 test_no_implicit_conversion<FromL>();
171 test_rank_mismatch<FromL>();
172 test_static_extent_mismatch<FromL>();
173}
174
175constexpr bool test() {
176 test_layout<std::layout_right>();
177 test_layout<std::layout_left>();
178 test_layout<std::layout_stride>();
179 test_layout<always_convertible_layout>();
180 return true;
181}
182
183int main(int, char**) {
184 test();
185 static_assert(test());
186 return 0;
187}
188

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