1 // -*- C++ -*- 2 //===----------------------------------------------------------------------===// 3 // 4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5 // See https://llvm.org/LICENSE.txt for license information. 6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7 // 8 // Kokkos v. 4.0 9 // Copyright (2022) National Technology & Engineering 10 // Solutions of Sandia, LLC (NTESS). 11 // 12 // Under the terms of Contract DE-NA0003525 with NTESS, 13 // the U.S. Government retains certain rights in this software. 14 // 15 //===---------------------------------------------------------------------===// 16 17 #ifndef _LIBCPP___MDSPAN_MDSPAN_H 18 #define _LIBCPP___MDSPAN_MDSPAN_H 19 20 #include <__assert> 21 #include <__config> 22 #include <__fwd/mdspan.h> 23 #include <__mdspan/default_accessor.h> 24 #include <__mdspan/extents.h> 25 #include <__type_traits/extent.h> 26 #include <__type_traits/is_abstract.h> 27 #include <__type_traits/is_array.h> 28 #include <__type_traits/is_constructible.h> 29 #include <__type_traits/is_convertible.h> 30 #include <__type_traits/is_nothrow_constructible.h> 31 #include <__type_traits/is_pointer.h> 32 #include <__type_traits/is_same.h> 33 #include <__type_traits/rank.h> 34 #include <__type_traits/remove_all_extents.h> 35 #include <__type_traits/remove_cv.h> 36 #include <__type_traits/remove_pointer.h> 37 #include <__type_traits/remove_reference.h> 38 #include <__utility/integer_sequence.h> 39 #include <array> 40 #include <span> 41 42 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 43 # pragma GCC system_header 44 #endif 45 46 _LIBCPP_PUSH_MACROS 47 #include <__undef_macros> 48 49 _LIBCPP_BEGIN_NAMESPACE_STD 50 51 #if _LIBCPP_STD_VER >= 23 52 53 // Helper for lightweight test checking that one did pass a layout policy as LayoutPolicy template argument 54 namespace __mdspan_detail { 55 template <class _Layout, class _Extents> 56 concept __has_invalid_mapping = !requires { typename _Layout::template mapping<_Extents>; }; 57 } // namespace __mdspan_detail 58 59 template <class _ElementType, 60 class _Extents, 61 class _LayoutPolicy = layout_right, 62 class _AccessorPolicy = default_accessor<_ElementType> > 63 class mdspan { 64 private: 65 static_assert(__mdspan_detail::__is_extents_v<_Extents>, 66 "mdspan: Extents template parameter must be a specialization of extents."); 67 static_assert(!is_array_v<_ElementType>, "mdspan: ElementType template parameter may not be an array type"); 68 static_assert(!is_abstract_v<_ElementType>, "mdspan: ElementType template parameter may not be an abstract class"); 69 static_assert(is_same_v<_ElementType, typename _AccessorPolicy::element_type>, 70 "mdspan: ElementType template parameter must match AccessorPolicy::element_type"); 71 static_assert(!__mdspan_detail::__has_invalid_mapping<_LayoutPolicy, _Extents>, 72 "mdspan: LayoutPolicy template parameter is invalid. A common mistake is to pass a layout mapping " 73 "instead of a layout policy"); 74 75 public: 76 using extents_type = _Extents; 77 using layout_type = _LayoutPolicy; 78 using accessor_type = _AccessorPolicy; 79 using mapping_type = typename layout_type::template mapping<extents_type>; 80 using element_type = _ElementType; 81 using value_type = remove_cv_t<element_type>; 82 using index_type = typename extents_type::index_type; 83 using size_type = typename extents_type::size_type; 84 using rank_type = typename extents_type::rank_type; 85 using data_handle_type = typename accessor_type::data_handle_type; 86 using reference = typename accessor_type::reference; 87 88 _LIBCPP_HIDE_FROM_ABI static constexpr rank_type rank() noexcept { return extents_type::rank(); } 89 _LIBCPP_HIDE_FROM_ABI static constexpr rank_type rank_dynamic() noexcept { return extents_type::rank_dynamic(); } 90 _LIBCPP_HIDE_FROM_ABI static constexpr size_t static_extent(rank_type __r) noexcept { 91 return extents_type::static_extent(__r); 92 } 93 _LIBCPP_HIDE_FROM_ABI constexpr index_type extent(rank_type __r) const noexcept { 94 return __map_.extents().extent(__r); 95 }; 96 97 public: 98 //-------------------------------------------------------------------------------- 99 // [mdspan.mdspan.cons], mdspan constructors, assignment, and destructor 100 101 _LIBCPP_HIDE_FROM_ABI constexpr mdspan() 102 requires((extents_type::rank_dynamic() > 0) && is_default_constructible_v<data_handle_type> && 103 is_default_constructible_v<mapping_type> && is_default_constructible_v<accessor_type>) 104 = default; 105 _LIBCPP_HIDE_FROM_ABI constexpr mdspan(const mdspan&) = default; 106 _LIBCPP_HIDE_FROM_ABI constexpr mdspan(mdspan&&) = default; 107 108 template <class... _OtherIndexTypes> 109 requires((is_convertible_v<_OtherIndexTypes, index_type> && ...) && 110 (is_nothrow_constructible_v<index_type, _OtherIndexTypes> && ...) && 111 ((sizeof...(_OtherIndexTypes) == rank()) || (sizeof...(_OtherIndexTypes) == rank_dynamic())) && 112 is_constructible_v<mapping_type, extents_type> && is_default_constructible_v<accessor_type>) 113 _LIBCPP_HIDE_FROM_ABI explicit constexpr mdspan(data_handle_type __p, _OtherIndexTypes... __exts) 114 : __ptr_(std::move(__p)), __map_(extents_type(static_cast<index_type>(std::move(__exts))...)), __acc_{} {} 115 116 template <class _OtherIndexType, size_t _Size> 117 requires(is_convertible_v<const _OtherIndexType&, index_type> && 118 is_nothrow_constructible_v<index_type, const _OtherIndexType&> && 119 ((_Size == rank()) || (_Size == rank_dynamic())) && is_constructible_v<mapping_type, extents_type> && 120 is_default_constructible_v<accessor_type>) 121 explicit(_Size != rank_dynamic()) 122 _LIBCPP_HIDE_FROM_ABI constexpr mdspan(data_handle_type __p, const array<_OtherIndexType, _Size>& __exts) 123 : __ptr_(std::move(__p)), __map_(extents_type(__exts)), __acc_{} {} 124 125 template <class _OtherIndexType, size_t _Size> 126 requires(is_convertible_v<const _OtherIndexType&, index_type> && 127 is_nothrow_constructible_v<index_type, const _OtherIndexType&> && 128 ((_Size == rank()) || (_Size == rank_dynamic())) && is_constructible_v<mapping_type, extents_type> && 129 is_default_constructible_v<accessor_type>) 130 explicit(_Size != rank_dynamic()) 131 _LIBCPP_HIDE_FROM_ABI constexpr mdspan(data_handle_type __p, span<_OtherIndexType, _Size> __exts) 132 : __ptr_(std::move(__p)), __map_(extents_type(__exts)), __acc_{} {} 133 134 _LIBCPP_HIDE_FROM_ABI constexpr mdspan(data_handle_type __p, const extents_type& __exts) 135 requires(is_default_constructible_v<accessor_type> && is_constructible_v<mapping_type, const extents_type&>) 136 : __ptr_(std::move(__p)), __map_(__exts), __acc_{} {} 137 138 _LIBCPP_HIDE_FROM_ABI constexpr mdspan(data_handle_type __p, const mapping_type& __m) 139 requires(is_default_constructible_v<accessor_type>) 140 : __ptr_(std::move(__p)), __map_(__m), __acc_{} {} 141 142 _LIBCPP_HIDE_FROM_ABI constexpr mdspan(data_handle_type __p, const mapping_type& __m, const accessor_type& __a) 143 : __ptr_(std::move(__p)), __map_(__m), __acc_(__a) {} 144 145 template <class _OtherElementType, class _OtherExtents, class _OtherLayoutPolicy, class _OtherAccessor> 146 requires(is_constructible_v<mapping_type, const typename _OtherLayoutPolicy::template mapping<_OtherExtents>&> && 147 is_constructible_v<accessor_type, const _OtherAccessor&>) 148 explicit(!is_convertible_v<const typename _OtherLayoutPolicy::template mapping<_OtherExtents>&, mapping_type> || 149 !is_convertible_v<const _OtherAccessor&, accessor_type>) 150 _LIBCPP_HIDE_FROM_ABI constexpr mdspan( 151 const mdspan<_OtherElementType, _OtherExtents, _OtherLayoutPolicy, _OtherAccessor>& __other) 152 : __ptr_(__other.__ptr_), __map_(__other.__map_), __acc_(__other.__acc_) { 153 static_assert(is_constructible_v<data_handle_type, const typename _OtherAccessor::data_handle_type&>, 154 "mdspan: incompatible data_handle_type for mdspan construction"); 155 static_assert( 156 is_constructible_v<extents_type, _OtherExtents>, "mdspan: incompatible extents for mdspan construction"); 157 158 // The following precondition is part of the standard, but is unlikely to be triggered. 159 // The extents constructor checks this and the mapping must be storing the extents, since 160 // its extents() function returns a const reference to extents_type. 161 // The only way this can be triggered is if the mapping conversion constructor would for example 162 // always construct its extents() only from the dynamic extents, instead of from the other extents. 163 if constexpr (rank() > 0) { 164 for (size_t __r = 0; __r < rank(); __r++) { 165 // Not catching this could lead to out of bounds errors later 166 // e.g. mdspan<int, dextents<char,1>, non_checking_layout> m = 167 // mdspan<int, dextents<unsigned, 1>, non_checking_layout>(ptr, 200); leads to an extent of -56 on m 168 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS( 169 (static_extent(__r) == dynamic_extent) || 170 (static_cast<index_type>(__other.extent(__r)) == static_cast<index_type>(static_extent(__r))), 171 "mdspan: conversion mismatch of source dynamic extents with static extents"); 172 } 173 } 174 } 175 176 _LIBCPP_HIDE_FROM_ABI constexpr mdspan& operator=(const mdspan&) = default; 177 _LIBCPP_HIDE_FROM_ABI constexpr mdspan& operator=(mdspan&&) = default; 178 179 //-------------------------------------------------------------------------------- 180 // [mdspan.mdspan.members], members 181 182 template <class... _OtherIndexTypes> 183 requires((is_convertible_v<_OtherIndexTypes, index_type> && ...) && 184 (is_nothrow_constructible_v<index_type, _OtherIndexTypes> && ...) && 185 (sizeof...(_OtherIndexTypes) == rank())) 186 _LIBCPP_HIDE_FROM_ABI constexpr reference operator[](_OtherIndexTypes... __indices) const { 187 // Note the standard layouts would also check this, but user provided ones may not, so we 188 // check the precondition here 189 _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__mdspan_detail::__is_multidimensional_index_in(extents(), __indices...), 190 "mdspan: operator[] out of bounds access"); 191 return __acc_.access(__ptr_, __map_(static_cast<index_type>(std::move(__indices))...)); 192 } 193 194 template <class _OtherIndexType> 195 requires(is_convertible_v<const _OtherIndexType&, index_type> && 196 is_nothrow_constructible_v<index_type, const _OtherIndexType&>) 197 _LIBCPP_HIDE_FROM_ABI constexpr reference operator[](const array< _OtherIndexType, rank()>& __indices) const { 198 return __acc_.access(__ptr_, [&]<size_t... _Idxs>(index_sequence<_Idxs...>) { 199 return __map_(__indices[_Idxs]...); 200 }(make_index_sequence<rank()>())); 201 } 202 203 template <class _OtherIndexType> 204 requires(is_convertible_v<const _OtherIndexType&, index_type> && 205 is_nothrow_constructible_v<index_type, const _OtherIndexType&>) 206 _LIBCPP_HIDE_FROM_ABI constexpr reference operator[](span<_OtherIndexType, rank()> __indices) const { 207 return __acc_.access(__ptr_, [&]<size_t... _Idxs>(index_sequence<_Idxs...>) { 208 return __map_(__indices[_Idxs]...); 209 }(make_index_sequence<rank()>())); 210 } 211 212 _LIBCPP_HIDE_FROM_ABI constexpr size_type size() const noexcept { 213 // Could leave this as only checked in debug mode: semantically size() is never 214 // guaranteed to be related to any accessible range 215 _LIBCPP_ASSERT_UNCATEGORIZED( 216 false == ([&]<size_t... _Idxs>(index_sequence<_Idxs...>) { 217 size_type __prod = 1; 218 return (__builtin_mul_overflow(__prod, extent(_Idxs), &__prod) || ... || false); 219 }(make_index_sequence<rank()>())), 220 "mdspan: size() is not representable as size_type"); 221 return [&]<size_t... _Idxs>(index_sequence<_Idxs...>) { 222 return ((static_cast<size_type>(__map_.extents().extent(_Idxs))) * ... * size_type(1)); 223 }(make_index_sequence<rank()>()); 224 } 225 226 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr bool empty() const noexcept { 227 return [&]<size_t... _Idxs>(index_sequence<_Idxs...>) { 228 return (rank() > 0) && ((__map_.extents().extent(_Idxs) == index_type(0)) || ... || false); 229 }(make_index_sequence<rank()>()); 230 } 231 232 _LIBCPP_HIDE_FROM_ABI friend constexpr void swap(mdspan& __x, mdspan& __y) noexcept { 233 swap(__x.__ptr_, __y.__ptr_); 234 swap(__x.__map_, __y.__map_); 235 swap(__x.__acc_, __y.__acc_); 236 } 237 238 _LIBCPP_HIDE_FROM_ABI constexpr const extents_type& extents() const noexcept { return __map_.extents(); }; 239 _LIBCPP_HIDE_FROM_ABI constexpr const data_handle_type& data_handle() const noexcept { return __ptr_; }; 240 _LIBCPP_HIDE_FROM_ABI constexpr const mapping_type& mapping() const noexcept { return __map_; }; 241 _LIBCPP_HIDE_FROM_ABI constexpr const accessor_type& accessor() const noexcept { return __acc_; }; 242 243 // per LWG-4021 "mdspan::is_always_meow() should be noexcept" 244 _LIBCPP_HIDE_FROM_ABI static constexpr bool is_always_unique() noexcept { return mapping_type::is_always_unique(); }; 245 _LIBCPP_HIDE_FROM_ABI static constexpr bool is_always_exhaustive() noexcept { 246 return mapping_type::is_always_exhaustive(); 247 }; 248 _LIBCPP_HIDE_FROM_ABI static constexpr bool is_always_strided() noexcept { 249 return mapping_type::is_always_strided(); 250 }; 251 252 _LIBCPP_HIDE_FROM_ABI constexpr bool is_unique() const { return __map_.is_unique(); }; 253 _LIBCPP_HIDE_FROM_ABI constexpr bool is_exhaustive() const { return __map_.is_exhaustive(); }; 254 _LIBCPP_HIDE_FROM_ABI constexpr bool is_strided() const { return __map_.is_strided(); }; 255 _LIBCPP_HIDE_FROM_ABI constexpr index_type stride(rank_type __r) const { return __map_.stride(__r); }; 256 257 private: 258 _LIBCPP_NO_UNIQUE_ADDRESS data_handle_type __ptr_{}; 259 _LIBCPP_NO_UNIQUE_ADDRESS mapping_type __map_{}; 260 _LIBCPP_NO_UNIQUE_ADDRESS accessor_type __acc_{}; 261 262 template <class, class, class, class> 263 friend class mdspan; 264 }; 265 266 # if _LIBCPP_STD_VER >= 26 267 template <class _ElementType, class... _OtherIndexTypes> 268 requires((is_convertible_v<_OtherIndexTypes, size_t> && ...) && (sizeof...(_OtherIndexTypes) > 0)) 269 explicit mdspan(_ElementType*, 270 _OtherIndexTypes...) -> mdspan<_ElementType, extents<size_t, __maybe_static_ext<_OtherIndexTypes>...>>; 271 # else 272 template <class _ElementType, class... _OtherIndexTypes> 273 requires((is_convertible_v<_OtherIndexTypes, size_t> && ...) && (sizeof...(_OtherIndexTypes) > 0)) 274 explicit mdspan(_ElementType*, 275 _OtherIndexTypes...) -> mdspan<_ElementType, dextents<size_t, sizeof...(_OtherIndexTypes)>>; 276 # endif 277 278 template <class _Pointer> 279 requires(is_pointer_v<remove_reference_t<_Pointer>>) 280 mdspan(_Pointer&&) -> mdspan<remove_pointer_t<remove_reference_t<_Pointer>>, extents<size_t>>; 281 282 template <class _CArray> 283 requires(is_array_v<_CArray> && (rank_v<_CArray> == 1)) 284 mdspan(_CArray&) -> mdspan<remove_all_extents_t<_CArray>, extents<size_t, extent_v<_CArray, 0>>>; 285 286 template <class _ElementType, class _OtherIndexType, size_t _Size> 287 mdspan(_ElementType*, const array<_OtherIndexType, _Size>&) -> mdspan<_ElementType, dextents<size_t, _Size>>; 288 289 template <class _ElementType, class _OtherIndexType, size_t _Size> 290 mdspan(_ElementType*, span<_OtherIndexType, _Size>) -> mdspan<_ElementType, dextents<size_t, _Size>>; 291 292 // This one is necessary because all the constructors take `data_handle_type`s, not 293 // `_ElementType*`s, and `data_handle_type` is taken from `accessor_type::data_handle_type`, which 294 // seems to throw off automatic deduction guides. 295 template <class _ElementType, class _OtherIndexType, size_t... _ExtentsPack> 296 mdspan(_ElementType*, const extents<_OtherIndexType, _ExtentsPack...>&) 297 -> mdspan<_ElementType, extents<_OtherIndexType, _ExtentsPack...>>; 298 299 template <class _ElementType, class _MappingType> 300 mdspan(_ElementType*, const _MappingType&) 301 -> mdspan<_ElementType, typename _MappingType::extents_type, typename _MappingType::layout_type>; 302 303 template <class _MappingType, class _AccessorType> 304 mdspan(const typename _AccessorType::data_handle_type, const _MappingType&, const _AccessorType&) 305 -> mdspan<typename _AccessorType::element_type, 306 typename _MappingType::extents_type, 307 typename _MappingType::layout_type, 308 _AccessorType>; 309 310 #endif // _LIBCPP_STD_VER >= 23 311 312 _LIBCPP_END_NAMESPACE_STD 313 314 _LIBCPP_POP_MACROS 315 316 #endif // _LIBCPP___MDSPAN_MDSPAN_H 317