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 iteration:
14//
15// template<class... Indices>
16// constexpr index_type operator()(Indices...) const noexcept;
17//
18// Constraints:
19// * sizeof...(Indices) == extents_type::rank() is true,
20// * (is_convertible_v<Indices, index_type> && ...) is true, and
21// * (is_nothrow_constructible_v<index_type, Indices> && ...) is true.
22//
23// Preconditions:
24// * extents_type::index-cast(i) is a multidimensional index in extents_.
25
26#include <cassert>
27#include <cstddef>
28#include <cstdint>
29#include <mdspan>
30#include <type_traits>
31
32#include "test_macros.h"
33
34#include "../ConvertibleToIntegral.h"
35
36template <class Mapping, class... Indices>
37concept operator_constraints = requires(Mapping m, Indices... idxs) {
38 { std::is_same_v<decltype(m(idxs...)), typename Mapping::index_type> };
39};
40
41template <class Mapping, class... Indices>
42 requires(operator_constraints<Mapping, Indices...>)
43constexpr bool check_operator_constraints(Mapping m, Indices... idxs) {
44 (void)m(idxs...);
45 return true;
46}
47
48template <class Mapping, class... Indices>
49constexpr bool check_operator_constraints(Mapping, Indices...) {
50 return false;
51}
52
53template <class M, class T, class... Args>
54constexpr void iterate_right(M m, T& count, Args... args) {
55 constexpr size_t r = sizeof...(Args);
56 if constexpr (M::extents_type::rank() == r) {
57 ASSERT_NOEXCEPT(m(args...));
58 assert(count == m(args...));
59 count++;
60 } else {
61 for (typename M::index_type i = 0; i < m.extents().extent(r); i++) {
62 iterate_right(m, count, args..., i);
63 }
64 }
65}
66
67template <class E, class... Args>
68constexpr void test_iteration(Args... args) {
69 using M = std::layout_right::mapping<E>;
70 M m(E(args...));
71
72 typename E::index_type count = 0;
73 iterate_right(m, count);
74}
75
76constexpr bool test() {
77 constexpr size_t D = std::dynamic_extent;
78 test_iteration<std::extents<int>>();
79 test_iteration<std::extents<unsigned, D>>(1);
80 test_iteration<std::extents<unsigned, D>>(7);
81 test_iteration<std::extents<unsigned, 7>>();
82 test_iteration<std::extents<unsigned, 7, 8>>();
83 test_iteration<std::extents<signed char, D, D, D, D>>(1, 1, 1, 1);
84
85 // Check operator constraint for number of arguments
86 static_assert(
87 check_operator_constraints(std::layout_right::mapping<std::extents<int, D>>(std::extents<int, D>(1)), 0));
88 static_assert(
89 !check_operator_constraints(std::layout_right::mapping<std::extents<int, D>>(std::extents<int, D>(1)), 0, 0));
90
91 // Check operator constraint for convertibility of arguments to index_type
92 static_assert(check_operator_constraints(
93 std::layout_right::mapping<std::extents<int, D>>(std::extents<int, D>(1)), IntType(0)));
94 static_assert(!check_operator_constraints(
95 std::layout_right::mapping<std::extents<unsigned, D>>(std::extents<unsigned, D>(1)), IntType(0)));
96
97 // Check operator constraint for no-throw-constructibility of index_type from arguments
98 static_assert(!check_operator_constraints(
99 std::layout_right::mapping<std::extents<unsigned char, D>>(std::extents<unsigned char, D>(1)), IntType(0)));
100
101 return true;
102}
103
104constexpr bool test_large() {
105 constexpr size_t D = std::dynamic_extent;
106 test_iteration<std::extents<int64_t, D, 8, D, D>>(7, 9, 10);
107 test_iteration<std::extents<int64_t, D, 8, 1, D>>(7, 10);
108 return true;
109}
110
111int main(int, char**) {
112 test();
113 static_assert(test());
114
115 // The large test iterates over ~10k loop indices.
116 // With assertions enabled this triggered the maximum default limit
117 // for steps in consteval expressions. Assertions roughly double the
118 // total number of instructions, so this was already close to the maximum.
119 test_large();
120 return 0;
121}
122

source code of libcxx/test/std/containers/views/mdspan/layout_right/index_operator.pass.cpp