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_LAYOUT_LEFT_H 18 #define _LIBCPP___MDSPAN_LAYOUT_LEFT_H 19 20 #include <__assert> 21 #include <__config> 22 #include <__fwd/mdspan.h> 23 #include <__mdspan/extents.h> 24 #include <__type_traits/is_constructible.h> 25 #include <__type_traits/is_convertible.h> 26 #include <__type_traits/is_nothrow_constructible.h> 27 #include <__utility/integer_sequence.h> 28 #include <array> 29 #include <cinttypes> 30 #include <cstddef> 31 #include <limits> 32 33 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 34 # pragma GCC system_header 35 #endif 36 37 _LIBCPP_PUSH_MACROS 38 #include <__undef_macros> 39 40 _LIBCPP_BEGIN_NAMESPACE_STD 41 42 #if _LIBCPP_STD_VER >= 23 43 44 template <class _Extents> 45 class layout_left::mapping { 46 public: 47 static_assert(__mdspan_detail::__is_extents<_Extents>::value, 48 "layout_left::mapping template argument must be a specialization of extents."); 49 50 using extents_type = _Extents; 51 using index_type = typename extents_type::index_type; 52 using size_type = typename extents_type::size_type; 53 using rank_type = typename extents_type::rank_type; 54 using layout_type = layout_left; 55 56 private: 57 _LIBCPP_HIDE_FROM_ABI static constexpr bool __required_span_size_is_representable(const extents_type& __ext) { 58 if constexpr (extents_type::rank() == 0) 59 return true; 60 61 index_type __prod = __ext.extent(0); 62 for (rank_type __r = 1; __r < extents_type::rank(); __r++) { 63 bool __overflowed = __builtin_mul_overflow(__prod, __ext.extent(__r), &__prod); 64 if (__overflowed) 65 return false; 66 } 67 return true; 68 } 69 70 static_assert((extents_type::rank_dynamic() > 0) || __required_span_size_is_representable(extents_type()), 71 "layout_left::mapping product of static extents must be representable as index_type."); 72 73 public: 74 // [mdspan.layout.left.cons], constructors 75 _LIBCPP_HIDE_FROM_ABI constexpr mapping() noexcept = default; 76 _LIBCPP_HIDE_FROM_ABI constexpr mapping(const mapping&) noexcept = default; 77 _LIBCPP_HIDE_FROM_ABI constexpr mapping(const extents_type& __ext) noexcept : __extents_(__ext) { 78 _LIBCPP_ASSERT(__required_span_size_is_representable(__ext), 79 "layout_left::mapping extents ctor: product of extents must be representable as index_type."); 80 } 81 82 template <class _OtherExtents> 83 requires(is_constructible_v<extents_type, _OtherExtents>) 84 _LIBCPP_HIDE_FROM_ABI constexpr explicit(!is_convertible_v<_OtherExtents, extents_type>) 85 mapping(const mapping<_OtherExtents>& __other) noexcept 86 : __extents_(__other.extents()) { 87 _LIBCPP_ASSERT( 88 __mdspan_detail::__is_representable_as<index_type>(__other.required_span_size()), 89 "layout_left::mapping converting ctor: other.required_span_size() must be representable as index_type."); 90 } 91 92 template <class _OtherExtents> 93 requires(is_constructible_v<extents_type, _OtherExtents> && _OtherExtents::rank() <= 1) 94 _LIBCPP_HIDE_FROM_ABI constexpr explicit(!is_convertible_v<_OtherExtents, extents_type>) 95 mapping(const layout_right::mapping<_OtherExtents>& __other) noexcept 96 : __extents_(__other.extents()) { 97 _LIBCPP_ASSERT( 98 __mdspan_detail::__is_representable_as<index_type>(__other.required_span_size()), 99 "layout_left::mapping converting ctor: other.required_span_size() must be representable as index_type."); 100 } 101 102 // FIXME: add when we add other layouts 103 # if 0 104 template<class _OtherExtents> 105 constexpr explicit(extents_type::rank() > 0) 106 mapping(const layout_stride::mapping_<OtherExtents>&) noexcept; 107 # endif 108 109 _LIBCPP_HIDE_FROM_ABI constexpr mapping& operator=(const mapping&) noexcept = default; 110 111 // [mdspan.layout.left.obs], observers 112 _LIBCPP_HIDE_FROM_ABI constexpr const extents_type& extents() const noexcept { return __extents_; } 113 114 _LIBCPP_HIDE_FROM_ABI constexpr index_type required_span_size() const noexcept { 115 index_type __size = 1; 116 for (size_t __r = 0; __r < extents_type::rank(); __r++) 117 __size *= __extents_.extent(__r); 118 return __size; 119 } 120 121 template <class... _Indices> 122 requires((sizeof...(_Indices) == extents_type::rank()) && (is_convertible_v<_Indices, index_type> && ...) && 123 (is_nothrow_constructible_v<index_type, _Indices> && ...)) 124 _LIBCPP_HIDE_FROM_ABI constexpr index_type operator()(_Indices... __idx) const noexcept { 125 _LIBCPP_ASSERT(__mdspan_detail::__is_multidimensional_index_in(__extents_, __idx...), 126 "layout_left::mapping: out of bounds indexing"); 127 array<index_type, extents_type::rank()> __idx_a{static_cast<index_type>(__idx)...}; 128 return [&]<size_t... _Pos>(index_sequence<_Pos...>) { 129 index_type __res = 0; 130 ((__res = __idx_a[extents_type::rank() - 1 - _Pos] + __extents_.extent(extents_type::rank() - 1 - _Pos) * __res), 131 ...); 132 return __res; 133 }(make_index_sequence<sizeof...(_Indices)>()); 134 } 135 136 _LIBCPP_HIDE_FROM_ABI static constexpr bool is_always_unique() noexcept { return true; } 137 _LIBCPP_HIDE_FROM_ABI static constexpr bool is_always_exhaustive() noexcept { return true; } 138 _LIBCPP_HIDE_FROM_ABI static constexpr bool is_always_strided() noexcept { return true; } 139 140 _LIBCPP_HIDE_FROM_ABI static constexpr bool is_unique() noexcept { return true; } 141 _LIBCPP_HIDE_FROM_ABI static constexpr bool is_exhaustive() noexcept { return true; } 142 _LIBCPP_HIDE_FROM_ABI static constexpr bool is_strided() noexcept { return true; } 143 144 _LIBCPP_HIDE_FROM_ABI constexpr index_type stride(rank_type __r) const noexcept 145 requires(extents_type::rank() > 0) 146 { 147 _LIBCPP_ASSERT(__r < extents_type::rank(), "layout_left::mapping::stride(): invalid rank index"); 148 index_type __s = 1; 149 for (rank_type __i = extents_type::rank() - 1; __i > __r; __i--) 150 __s *= __extents_.extent(__i); 151 return __s; 152 } 153 154 template <class _OtherExtents> 155 requires(_OtherExtents::rank() == extents_type::rank()) 156 _LIBCPP_HIDE_FROM_ABI friend constexpr bool 157 operator==(const mapping& __lhs, const mapping<_OtherExtents>& __rhs) noexcept { 158 return __lhs.extents() == __rhs.extents(); 159 } 160 161 private: 162 extents_type __extents_{}; // exposition only 163 }; 164 165 #endif // _LIBCPP_STD_VER >= 23 166 167 _LIBCPP_END_NAMESPACE_STD 168 169 _LIBCPP_POP_MACROS 170 171 #endif // _LIBCPP___MDSPAN_LAYOUT_LEFT_H 172