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 <mdspan>
27#include <cassert>
28#include <cstdint>
29
30#include "test_macros.h"
31
32#include "../ConvertibleToIntegral.h"
33
34template<class Mapping, class ... Indices>
35concept operator_constraints = requires(Mapping m, Indices ... idxs) {
36 {std::is_same_v<decltype(m(idxs...)), typename Mapping::index_type>};
37};
38
39template<class Mapping, class ... Indices>
40 requires(
41 operator_constraints<Mapping, Indices...>
42 )
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_left(M m, T& count, Args... args) {
55 constexpr int r = static_cast<int>(M::extents_type::rank()) - 1 - static_cast<int>(sizeof...(Args));
56 if constexpr (-1 == 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_left(m, count, i, args...);
63 }
64 }
65}
66
67template <class E, class... Args>
68constexpr void test_iteration(Args... args) {
69 using M = std::layout_left::mapping<E>;
70 M m(E(args...));
71
72 typename E::index_type count = 0;
73 iterate_left(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(check_operator_constraints(std::layout_left::mapping<std::extents<int, D>>(std::extents<int, D>(1)), 0));
87 static_assert(!check_operator_constraints(std::layout_left::mapping<std::extents<int, D>>(std::extents<int, D>(1)), 0, 0));
88
89 // Check operator constraint for convertibility of arguments to index_type
90 static_assert(check_operator_constraints(std::layout_left::mapping<std::extents<int, D>>(std::extents<int, D>(1)), IntType(0)));
91 static_assert(!check_operator_constraints(std::layout_left::mapping<std::extents<unsigned, D>>(std::extents<unsigned, D>(1)), IntType(0)));
92
93 // Check operator constraint for no-throw-constructibility of index_type from arguments
94 static_assert(!check_operator_constraints(std::layout_left::mapping<std::extents<unsigned char, D>>(std::extents<unsigned char, D>(1)), IntType(0)));
95
96 return true;
97}
98
99constexpr bool test_large() {
100 constexpr size_t D = std::dynamic_extent;
101 test_iteration<std::extents<int64_t, D, 8, D, D>>(7, 9, 10);
102 test_iteration<std::extents<int64_t, D, 8, 1, D>>(7, 10);
103 return true;
104}
105
106int main(int, char**) {
107 test();
108 static_assert(test());
109
110 // The large test iterates over ~10k loop indices.
111 // With assertions enabled this triggered the maximum default limit
112 // for steps in consteval expressions. Assertions roughly double the
113 // total number of instructions, so this was already close to the maximum.
114 test_large();
115 return 0;
116}
117

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