libcxx/test/std/containers/views/mdspan/layout_right/static_requirements.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 // A type M meets the layout mapping requirements if
  14 //    - M models copyable and equality_comparable,
  15 //    - is_nothrow_move_constructible_v<M> is true,
  16 //    - is_nothrow_move_assignable_v<M> is true,
  17 //    - is_nothrow_swappable_v<M> is true, and
  18 //
  19 // the following types and expressions are well-formed and have the specified semantics.
  20 //
  21 //  typename M::extents_type
  22 //    Result: A type that is a specialization of extents.
  23 //
  24 //  typename M::index_type
  25 //    Result: typename M::extents_type::index_type.
  26 //
  27 //  typename M::rank_type
  28 //    Result: typename M::extents_type::rank_type.
  29 //
  30 //  typename M::layout_type
  31 //    Result: A type MP that meets the layout mapping policy requirements ([mdspan.layout.policy.reqmts]) and for which is-mapping-of<MP, M> is true.
  32 //
  33 //  m.extents()
  34 //    Result: const typename M::extents_type&
  35 //
  36 //  m(i...)
  37 //    Result: typename M::index_type
  38 //    Returns: A nonnegative integer less than numeric_limits<typename M::index_type>::max() and less than or equal to numeric_limits<size_t>::max().
  39 //
  40 //  m(i...) == m(static_cast<typename M::index_type>(i)...)
  41 //    Result: bool
  42 //    Returns: true
  43 //
  44 //  m.required_span_size()
  45 //    Result: typename M::index_type
  46 //    Returns: If the size of the multidimensional index space m.extents() is 0, then 0, else 1 plus the maximum value of m(i...) for all i.
  47 //
  48 //  m.is_unique()
  49 //    Result: bool
  50 //    Returns: true only if for every i and j where (i != j || ...) is true, m(i...) != m(j...) is true.
  51 //
  52 //  m.is_exhaustive()
  53 //    Result: bool
  54 //    Returns: true only if for all k in the range [0, m.required_span_size()) there exists an i such that m(i...) equals k.
  55 //
  56 //  m.is_strided()
  57 //    Result: bool
  58 //    Returns: true only if for every rank index r of m.extents() there exists an integer
  59 //             sr such that, for all i where (i+dr) is a multidimensional index in m.extents() ([mdspan.overview]),
  60 //             m((i + dr)...) - m(i...) equals sr
  61 //
  62 //  m.stride(r)
  63 //    Preconditions: m.is_strided() is true.
  64 //    Result: typename M::index_type
  65 //    Returns: sr as defined in m.is_strided() above.
  66 //
  67 //  M::is_always_unique()
  68 //    Result: A constant expression ([expr.const]) of type bool.
  69 //    Returns: true only if m.is_unique() is true for all possible objects m of type M.
  70 //
  71 //  M::is_always_exhaustive()
  72 //    Result: A constant expression ([expr.const]) of type bool.
  73 //    Returns: true only if m.is_exhaustive() is true for all possible objects m of type M.
  74 //
  75 //  M::is_always_strided()
  76 //    Result: A constant expression ([expr.const]) of type bool.
  77 //    Returns: true only if m.is_strided() is true for all possible objects m of type M.
  78
  79 #include <cassert>
  80 #include <cstddef>
  81 #include <mdspan>
  82 #include <span> // dynamic_extent
  83 #include <type_traits>
  84 #include <utility>
  85
  86 #include "test_macros.h"
  87
  88 // Common requirements of all layout mappings
  89 template <class M, size_t... Idxs>
  90 void test_mapping_requirements(std::index_sequence<Idxs...>) {
  91   using E = typename M::extents_type;
  92   LIBCPP_STATIC_ASSERT(std::__mdspan_detail::__is_extents_v<E>);
  93   static_assert(std::is_copy_constructible_v<M>);
  94   static_assert(std::is_nothrow_move_constructible_v<M>);
  95   static_assert(std::is_nothrow_move_assignable_v<M>);
  96   static_assert(std::is_nothrow_swappable_v<M>);
  97   ASSERT_SAME_TYPE(typename M::index_type, typename E::index_type);
  98   ASSERT_SAME_TYPE(typename M::size_type, typename E::size_type);
  99   ASSERT_SAME_TYPE(typename M::rank_type, typename E::rank_type);
 100   ASSERT_SAME_TYPE(typename M::layout_type, std::layout_right);
 101   ASSERT_SAME_TYPE(typename M::layout_type::template mapping<E>, M);
 102   static_assert(std::is_same_v<decltype(std::declval<M>().extents()), const E&>);
 103   static_assert(std::is_same_v<decltype(std::declval<M>()(Idxs...)), typename M::index_type>);
 104   static_assert(std::is_same_v<decltype(std::declval<M>().required_span_size()), typename M::index_type>);
 105   static_assert(std::is_same_v<decltype(std::declval<M>().is_unique()), bool>);
 106   static_assert(std::is_same_v<decltype(std::declval<M>().is_exhaustive()), bool>);
 107   static_assert(std::is_same_v<decltype(std::declval<M>().is_strided()), bool>);
 108   if constexpr (E::rank() > 0)
 109     static_assert(std::is_same_v<decltype(std::declval<M>().stride(0)), typename M::index_type>);
 110   static_assert(std::is_same_v<decltype(M::is_always_unique()), bool>);
 111   static_assert(std::is_same_v<decltype(M::is_always_exhaustive()), bool>);
 112   static_assert(std::is_same_v<decltype(M::is_always_strided()), bool>);
 113 }
 114
 115 template <class L, class E>
 116 void test_layout_mapping_requirements() {
 117   using M = typename L::template mapping<E>;
 118   test_mapping_requirements<M>(std::make_index_sequence<E::rank()>());
 119 }
 120
 121 template <class E>
 122 void test_layout_mapping_right() {
 123   test_layout_mapping_requirements<std::layout_right, E>();
 124 }
 125
 126 int main(int, char**) {
 127   constexpr size_t D = std::dynamic_extent;
 128   test_layout_mapping_right<std::extents<int>>();
 129   test_layout_mapping_right<std::extents<signed char, 4, 5>>();
 130   test_layout_mapping_right<std::extents<unsigned, D, 4>>();
 131   test_layout_mapping_right<std::extents<size_t, D, D, D, D>>();
 132   return 0;
 133 }