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

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