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 <mdspan>
  27 #include <cassert>
  28 #include <cstdint>
  29
  30 #include "test_macros.h"
  31
  32 #include "../ConvertibleToIntegral.h"
  33
  34 template<class Mapping, class ... Indices>
  35 concept operator_constraints = requires(Mapping m, Indices ... idxs) {
  36   {std::is_same_v<decltype(m(idxs...)), typename Mapping::index_type>};
  37 };
  38
  39 template<class Mapping, class ... Indices>
  40   requires(
  41     operator_constraints<Mapping, Indices...>
  42   )
  43 constexpr bool check_operator_constraints(Mapping m, Indices ... idxs) {
  44   (void) m(idxs...);
  45   return true;
  46 }
  47
  48 template<class Mapping, class ... Indices>
  49 constexpr bool check_operator_constraints(Mapping, Indices ...) {
  50   return false;
  51 }
  52
  53 template <class M, class T, class... Args>
  54 constexpr 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
  67 template <class E, class... Args>
  68 constexpr 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
  76 constexpr 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_right::mapping<std::extents<int, D>>(std::extents<int, D>(1)), 0));
  87   static_assert(!check_operator_constraints(std::layout_right::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_right::mapping<std::extents<int, D>>(std::extents<int, D>(1)), IntType(0)));
  91   static_assert(!check_operator_constraints(std::layout_right::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_right::mapping<std::extents<unsigned char, D>>(std::extents<unsigned char, D>(1)), IntType(0)));
  95
  96   return true;
  97 }
  98
  99 constexpr 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
 106 int 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 }