diff options
Diffstat (limited to 'libstdc++-v3/include/std/mdspan')
| -rw-r--r-- | libstdc++-v3/include/std/mdspan | 726 |
1 files changed, 713 insertions, 13 deletions
diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan index bcf2fa6..6dc2441 100644 --- a/libstdc++-v3/include/std/mdspan +++ b/libstdc++-v3/include/std/mdspan @@ -69,12 +69,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // // If __r is the index of a dynamic extent, then // _S_dynamic_index[__r] is the index of that extent in - // _M_dynamic_extents. + // _M_dyn_exts. static constexpr auto _S_dynamic_index = [] consteval { array<size_t, _S_rank+1> __ret; size_t __dyn = 0; - for(size_t __i = 0; __i < _S_rank; ++__i) + for (size_t __i = 0; __i < _S_rank; ++__i) { __ret[__i] = __dyn; __dyn += _S_is_dyn(_Extents[__i]); @@ -105,7 +105,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { auto __se = _Extents[__r]; if (__se == dynamic_extent) - return _M_dynamic_extents[_S_dynamic_index[__r]]; + return _M_dyn_exts[_S_dynamic_index[__r]]; else return __se; } @@ -114,12 +114,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION constexpr void _M_init_dynamic_extents(_GetOtherExtent __get_extent) noexcept { - for(size_t __i = 0; __i < _S_rank_dynamic; ++__i) + for (size_t __i = 0; __i < _S_rank_dynamic; ++__i) { size_t __di = __i; if constexpr (_OtherRank != _S_rank_dynamic) __di = _S_dynamic_index_inv[__i]; - _M_dynamic_extents[__i] = _S_int_cast(__get_extent(__di)); + _M_dyn_exts[__i] = _S_int_cast(__get_extent(__di)); } } @@ -144,9 +144,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { return __exts[__i]; }); } + static constexpr span<const size_t> + _S_static_extents(size_t __begin, size_t __end) noexcept + { + return {_Extents.data() + __begin, _Extents.data() + __end}; + } + + constexpr span<const _IndexType> + _M_dynamic_extents(size_t __begin, size_t __end) const noexcept + requires (_Extents.size() > 0) + { + return {_M_dyn_exts + _S_dynamic_index[__begin], + _M_dyn_exts + _S_dynamic_index[__end]}; + } + private: using _S_storage = __array_traits<_IndexType, _S_rank_dynamic>::_Type; - [[no_unique_address]] _S_storage _M_dynamic_extents{}; + [[no_unique_address]] _S_storage _M_dyn_exts{}; }; template<typename _OIndexType, typename _SIndexType> @@ -160,6 +174,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION || _Extent <= numeric_limits<_IndexType>::max(); } + namespace __mdspan + { + template<typename _Extents> + constexpr span<const size_t> + __static_extents(size_t __begin = 0, size_t __end = _Extents::rank()) + noexcept + { return _Extents::_S_storage::_S_static_extents(__begin, __end); } + + template<typename _Extents> + constexpr span<const typename _Extents::index_type> + __dynamic_extents(const _Extents& __exts, size_t __begin = 0, + size_t __end = _Extents::rank()) noexcept + { + return __exts._M_exts._M_dynamic_extents(__begin, __end); + } + } + template<typename _IndexType, size_t... _Extents> class extents { @@ -197,7 +228,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION if constexpr (rank() == 0) __builtin_trap(); else - return _M_dynamic_extents._M_extent(__r); + return _M_exts._M_extent(__r); } constexpr @@ -233,14 +264,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION requires (_S_is_compatible_extents<_OExtents...>()) constexpr explicit(_S_ctor_explicit<_OIndexType, _OExtents...>()) extents(const extents<_OIndexType, _OExtents...>& __other) noexcept - : _M_dynamic_extents(__other._M_dynamic_extents) + : _M_exts(__other._M_exts) { } template<__mdspan::__valid_index_type<index_type>... _OIndexTypes> requires (sizeof...(_OIndexTypes) == rank() || sizeof...(_OIndexTypes) == rank_dynamic()) constexpr explicit extents(_OIndexTypes... __exts) noexcept - : _M_dynamic_extents(span<const _IndexType, sizeof...(_OIndexTypes)>( + : _M_exts(span<const _IndexType, sizeof...(_OIndexTypes)>( initializer_list{_S_storage::_S_int_cast(__exts)...})) { } @@ -248,15 +279,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION requires (_Nm == rank() || _Nm == rank_dynamic()) constexpr explicit(_Nm != rank_dynamic()) extents(span<_OIndexType, _Nm> __exts) noexcept - : _M_dynamic_extents(span<const _OIndexType, _Nm>(__exts)) + : _M_exts(span<const _OIndexType, _Nm>(__exts)) { } - template<__mdspan::__valid_index_type<index_type> _OIndexType, size_t _Nm> requires (_Nm == rank() || _Nm == rank_dynamic()) constexpr explicit(_Nm != rank_dynamic()) extents(const array<_OIndexType, _Nm>& __exts) noexcept - : _M_dynamic_extents(span<const _OIndexType, _Nm>(__exts)) + : _M_exts(span<const _OIndexType, _Nm>(__exts)) { } template<typename _OIndexType, size_t... _OExtents> @@ -276,9 +306,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION } private: + friend span<const size_t> + __mdspan::__static_extents<extents>(size_t, size_t); + + friend span<const index_type> + __mdspan::__dynamic_extents<extents>(const extents&, size_t, size_t); + using _S_storage = __mdspan::_ExtentsStorage< _IndexType, array<size_t, sizeof...(_Extents)>{_Extents...}>; - [[no_unique_address]] _S_storage _M_dynamic_extents; + [[no_unique_address]] _S_storage _M_exts; template<typename _OIndexType, size_t... _OExtents> friend class extents; @@ -286,6 +322,69 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION namespace __mdspan { + template<typename _Tp, size_t _Nm> + constexpr bool + __contains_zero(span<_Tp, _Nm> __exts) noexcept + { + for (size_t __i = 0; __i < __exts.size(); ++__i) + if (__exts[__i] == 0) + return true; + return false; + } + + template<typename _Extents> + constexpr bool + __empty(const _Extents& __exts) noexcept + { + if constexpr (__contains_zero(__static_extents<_Extents>())) + return true; + else if constexpr (_Extents::rank_dynamic() > 0) + return __contains_zero(__dynamic_extents(__exts)); + else + return false; + } + + constexpr size_t + __static_extents_prod(const auto& __sta_exts) noexcept + { + size_t __ret = 1; + for (auto __factor : __sta_exts) + if (__factor != dynamic_extent) + __ret *= __factor; + return __ret; + } + + template<typename _Extents> + constexpr typename _Extents::index_type + __exts_prod(const _Extents& __exts, size_t __begin, size_t __end) noexcept + { + using _IndexType = typename _Extents::index_type; + + size_t __ret = 1; + if constexpr (_Extents::rank_dynamic() != _Extents::rank()) + { + auto __sta_exts = __static_extents<_Extents>(__begin, __end); + __ret = __static_extents_prod(__sta_exts); + if (__ret == 0) + return 0; + } + + if constexpr (_Extents::rank_dynamic() > 0) + for (auto __factor : __dynamic_extents(__exts, __begin, __end)) + __ret *= size_t(__factor); + return _IndexType(__ret); + } + + template<typename _Extents> + constexpr typename _Extents::index_type + __fwd_prod(const _Extents& __exts, size_t __r) noexcept + { return __exts_prod(__exts, 0, __r); } + + template<typename _Extents> + constexpr typename _Extents::index_type + __rev_prod(const _Extents& __exts, size_t __r) noexcept + { return __exts_prod(__exts, __r + 1, __exts.rank()); } + template<typename _IndexType, size_t... _Counts> auto __build_dextents_type(integer_sequence<size_t, _Counts...>) -> extents<_IndexType, ((void) _Counts, dynamic_extent)...>; @@ -304,6 +403,607 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION explicit extents(_Integrals...) -> extents<size_t, __mdspan::__dynamic_extent<_Integrals>()...>; + struct layout_left + { + template<typename _Extents> + class mapping; + }; + + struct layout_right + { + template<typename _Extents> + class mapping; + }; + + struct layout_stride + { + template<typename _Extents> + class mapping; + }; + + namespace __mdspan + { + template<typename _Tp> + constexpr bool __is_extents = false; + + template<typename _IndexType, size_t... _Extents> + constexpr bool __is_extents<extents<_IndexType, _Extents...>> = true; + + template<typename _Extents, typename... _Indices> + constexpr typename _Extents::index_type + __linear_index_left(const _Extents& __exts, _Indices... __indices) + noexcept + { + using _IndexType = typename _Extents::index_type; + _IndexType __res = 0; + if constexpr (sizeof...(__indices) > 0) + { + _IndexType __mult = 1; + auto __update = [&, __pos = 0u](_IndexType __idx) mutable + { + __res += __idx * __mult; + __mult *= __exts.extent(__pos); + ++__pos; + }; + (__update(__indices), ...); + } + return __res; + } + + template<typename _Extents, + typename _IndexType = typename _Extents::index_type> + consteval _IndexType + __static_quotient(_IndexType __nom = numeric_limits<_IndexType>::max()) + { + auto __sta_exts = __static_extents<_Extents>(); + for (auto __factor : __sta_exts) + { + if (__factor != dynamic_extent) + __nom /= _IndexType(__factor); + if (__nom == 0) + break; + } + return __nom; + } + + template<typename _Extents> + constexpr bool + __is_representable_extents(const _Extents& __exts) noexcept + { + using _IndexType = _Extents::index_type; + + if constexpr (__contains_zero(__static_extents<_Extents>())) + return true; + else + { + constexpr auto __sta_quo = __static_quotient<_Extents>(); + if constexpr (_Extents::rank_dynamic() == 0) + return __sta_quo != 0; + else + { + auto __dyn_exts = __dynamic_extents(__exts); + if (__contains_zero(__dyn_exts)) + return true; + + if constexpr (__sta_quo == 0) + return false; + else + { + auto __dyn_quo = _IndexType(__sta_quo); + for (auto __factor : __dyn_exts) + { + __dyn_quo /= __factor; + if (__dyn_quo == 0) + return false; + } + return true; + } + } + } + } + + template<typename _Extents, typename _IndexType> + concept __representable_size = _Extents::rank_dynamic() != 0 + || __contains_zero(__static_extents<_Extents>()) + || (__static_quotient<_Extents, _IndexType>() != 0); + + template<typename _Layout, typename _Mapping> + concept __mapping_of = + is_same_v<typename _Layout::mapping<typename _Mapping::extents_type>, + _Mapping>; + + template<typename _Mapping> + concept __standardized_mapping = __mapping_of<layout_left, _Mapping> + || __mapping_of<layout_right, _Mapping> + || __mapping_of<layout_stride, _Mapping>; + + // A tag type to create internal ctors. + class __internal_ctor + { }; + } + + template<typename _Extents> + class layout_left::mapping + { + public: + using extents_type = _Extents; + using index_type = typename extents_type::index_type; + using size_type = typename extents_type::size_type; + using rank_type = typename extents_type::rank_type; + using layout_type = layout_left; + + static_assert(__mdspan::__representable_size<extents_type, index_type>, + "The size of extents_type must be representable as index_type"); + + constexpr + mapping() noexcept = default; + + constexpr + mapping(const mapping&) noexcept = default; + + constexpr + mapping(const extents_type& __extents) noexcept + : _M_extents(__extents) + { __glibcxx_assert(__mdspan::__is_representable_extents(_M_extents)); } + + template<typename _OExtents> + requires is_constructible_v<extents_type, _OExtents> + constexpr explicit(!is_convertible_v<_OExtents, extents_type>) + mapping(const mapping<_OExtents>& __other) noexcept + : mapping(__other.extents(), __mdspan::__internal_ctor{}) + { } + + template<typename _OExtents> + requires (extents_type::rank() <= 1) + && is_constructible_v<extents_type, _OExtents> + constexpr explicit(!is_convertible_v<_OExtents, extents_type>) + mapping(const layout_right::mapping<_OExtents>& __other) noexcept + : mapping(__other.extents(), __mdspan::__internal_ctor{}) + { } + + // noexcept for consistency with other layouts. + template<typename _OExtents> + requires is_constructible_v<extents_type, _OExtents> + constexpr explicit(extents_type::rank() > 0) + mapping(const layout_stride::mapping<_OExtents>& __other) noexcept + : mapping(__other.extents(), __mdspan::__internal_ctor{}) + { __glibcxx_assert(*this == __other); } + + constexpr mapping& + operator=(const mapping&) noexcept = default; + + constexpr const extents_type& + extents() const noexcept { return _M_extents; } + + constexpr index_type + required_span_size() const noexcept + { return __mdspan::__fwd_prod(_M_extents, extents_type::rank()); } + + template<__mdspan::__valid_index_type<index_type>... _Indices> + requires (sizeof...(_Indices) == extents_type::rank()) + constexpr index_type + operator()(_Indices... __indices) const noexcept + { + return __mdspan::__linear_index_left(_M_extents, + static_cast<index_type>(__indices)...); + } + + static constexpr bool + is_always_unique() noexcept { return true; } + + static constexpr bool + is_always_exhaustive() noexcept { return true; } + + static constexpr bool + is_always_strided() noexcept { return true; } + + static constexpr bool + is_unique() noexcept { return true; } + + static constexpr bool + is_exhaustive() noexcept { return true; } + + static constexpr bool + is_strided() noexcept { return true; } + + constexpr index_type + stride(rank_type __i) const noexcept + requires (extents_type::rank() > 0) + { + __glibcxx_assert(__i < extents_type::rank()); + return __mdspan::__fwd_prod(_M_extents, __i); + } + + template<typename _OExtents> + requires (extents_type::rank() == _OExtents::rank()) + friend constexpr bool + operator==(const mapping& __self, const mapping<_OExtents>& __other) + noexcept + { return __self.extents() == __other.extents(); } + + private: + template<typename _OExtents> + constexpr explicit + mapping(const _OExtents& __oexts, __mdspan::__internal_ctor) noexcept + : _M_extents(__oexts) + { + static_assert(__mdspan::__representable_size<_OExtents, index_type>, + "The size of OtherExtents must be representable as index_type"); + __glibcxx_assert(__mdspan::__is_representable_extents(_M_extents)); + } + + [[no_unique_address]] extents_type _M_extents{}; + }; + + namespace __mdspan + { + template<typename _Extents, typename... _Indices> + constexpr typename _Extents::index_type + __linear_index_right(const _Extents& __exts, _Indices... __indices) + noexcept + { + using _IndexType = typename _Extents::index_type; + array<_IndexType, sizeof...(__indices)> __ind_arr{__indices...}; + _IndexType __res = 0; + if constexpr (sizeof...(__indices) > 0) + { + _IndexType __mult = 1; + auto __update = [&, __pos = __exts.rank()](_IndexType) mutable + { + --__pos; + __res += __ind_arr[__pos] * __mult; + __mult *= __exts.extent(__pos); + }; + (__update(__indices), ...); + } + return __res; + } + } + + template<typename _Extents> + class layout_right::mapping + { + public: + using extents_type = _Extents; + using index_type = typename extents_type::index_type; + using size_type = typename extents_type::size_type; + using rank_type = typename extents_type::rank_type; + using layout_type = layout_right; + + static_assert(__mdspan::__representable_size<extents_type, index_type>, + "The size of extents_type must be representable as index_type"); + + constexpr + mapping() noexcept = default; + + constexpr + mapping(const mapping&) noexcept = default; + + constexpr + mapping(const extents_type& __extents) noexcept + : _M_extents(__extents) + { __glibcxx_assert(__mdspan::__is_representable_extents(_M_extents)); } + + template<typename _OExtents> + requires is_constructible_v<extents_type, _OExtents> + constexpr explicit(!is_convertible_v<_OExtents, extents_type>) + mapping(const mapping<_OExtents>& __other) noexcept + : mapping(__other.extents(), __mdspan::__internal_ctor{}) + { } + + template<typename _OExtents> + requires (extents_type::rank() <= 1) + && is_constructible_v<extents_type, _OExtents> + constexpr explicit(!is_convertible_v<_OExtents, extents_type>) + mapping(const layout_left::mapping<_OExtents>& __other) noexcept + : mapping(__other.extents(), __mdspan::__internal_ctor{}) + { } + + template<typename _OExtents> + requires is_constructible_v<extents_type, _OExtents> + constexpr explicit(extents_type::rank() > 0) + mapping(const layout_stride::mapping<_OExtents>& __other) noexcept + : mapping(__other.extents(), __mdspan::__internal_ctor{}) + { __glibcxx_assert(*this == __other); } + + constexpr mapping& + operator=(const mapping&) noexcept = default; + + constexpr const extents_type& + extents() const noexcept { return _M_extents; } + + constexpr index_type + required_span_size() const noexcept + { return __mdspan::__fwd_prod(_M_extents, extents_type::rank()); } + + template<__mdspan::__valid_index_type<index_type>... _Indices> + requires (sizeof...(_Indices) == extents_type::rank()) + constexpr index_type + operator()(_Indices... __indices) const noexcept + { + return __mdspan::__linear_index_right( + _M_extents, static_cast<index_type>(__indices)...); + } + + static constexpr bool + is_always_unique() noexcept + { return true; } + + static constexpr bool + is_always_exhaustive() noexcept + { return true; } + + static constexpr bool + is_always_strided() noexcept + { return true; } + + static constexpr bool + is_unique() noexcept + { return true; } + + static constexpr bool + is_exhaustive() noexcept + { return true; } + + static constexpr bool + is_strided() noexcept + { return true; } + + constexpr index_type + stride(rank_type __i) const noexcept + requires (extents_type::rank() > 0) + { + __glibcxx_assert(__i < extents_type::rank()); + return __mdspan::__rev_prod(_M_extents, __i); + } + + template<typename _OExtents> + requires (extents_type::rank() == _OExtents::rank()) + friend constexpr bool + operator==(const mapping& __self, const mapping<_OExtents>& __other) + noexcept + { return __self.extents() == __other.extents(); } + + private: + template<typename _OExtents> + constexpr explicit + mapping(const _OExtents& __oexts, __mdspan::__internal_ctor) noexcept + : _M_extents(__oexts) + { + static_assert(__mdspan::__representable_size<_OExtents, index_type>, + "The size of OtherExtents must be representable as index_type"); + __glibcxx_assert(__mdspan::__is_representable_extents(_M_extents)); + } + + [[no_unique_address]] extents_type _M_extents{}; + }; + + namespace __mdspan + { + template<typename _Mp> + concept __mapping_alike = requires + { + requires __is_extents<typename _Mp::extents_type>; + { _Mp::is_always_strided() } -> same_as<bool>; + { _Mp::is_always_exhaustive() } -> same_as<bool>; + { _Mp::is_always_unique() } -> same_as<bool>; + bool_constant<_Mp::is_always_strided()>::value; + bool_constant<_Mp::is_always_exhaustive()>::value; + bool_constant<_Mp::is_always_unique()>::value; + }; + + template<typename _Mapping> + constexpr typename _Mapping::index_type + __offset(const _Mapping& __m) noexcept + { + using _IndexType = typename _Mapping::index_type; + constexpr auto __rank = _Mapping::extents_type::rank(); + + if constexpr (__standardized_mapping<_Mapping>) + return 0; + else if (__empty(__m.extents())) + return 0; + else + { + auto __impl = [&__m]<size_t... _Counts>(index_sequence<_Counts...>) + { return __m(((void) _Counts, _IndexType(0))...); }; + return __impl(make_index_sequence<__rank>()); + } + } + + template<typename _Mapping, typename... _Indices> + constexpr typename _Mapping::index_type + __linear_index_strides(const _Mapping& __m, _Indices... __indices) + noexcept + { + using _IndexType = typename _Mapping::index_type; + _IndexType __res = 0; + if constexpr (sizeof...(__indices) > 0) + { + auto __update = [&, __pos = 0u](_IndexType __idx) mutable + { + __res += __idx * __m.stride(__pos++); + }; + (__update(__indices), ...); + } + return __res; + } + } + + template<typename _Extents> + class layout_stride::mapping + { + public: + using extents_type = _Extents; + using index_type = typename extents_type::index_type; + using size_type = typename extents_type::size_type; + using rank_type = typename extents_type::rank_type; + using layout_type = layout_stride; + + static_assert(__mdspan::__representable_size<extents_type, index_type>, + "The size of extents_type must be representable as index_type"); + + constexpr + mapping() noexcept + { + // The precondition is either statically asserted, or automatically + // satisfied because dynamic extents are zero-initialized. + size_t __stride = 1; + for (size_t __i = extents_type::rank(); __i > 0; --__i) + { + _M_strides[__i - 1] = index_type(__stride); + __stride *= size_t(_M_extents.extent(__i - 1)); + } + } + + constexpr + mapping(const mapping&) noexcept = default; + + template<__mdspan::__valid_index_type<index_type> _OIndexType> + constexpr + mapping(const extents_type& __exts, + span<_OIndexType, extents_type::rank()> __strides) noexcept + : _M_extents(__exts) + { + for (size_t __i = 0; __i < extents_type::rank(); ++__i) + _M_strides[__i] = index_type(as_const(__strides[__i])); + } + + template<__mdspan::__valid_index_type<index_type> _OIndexType> + constexpr + mapping(const extents_type& __exts, + const array<_OIndexType, extents_type::rank()>& __strides) + noexcept + : mapping(__exts, + span<const _OIndexType, extents_type::rank()>(__strides)) + { } + + template<__mdspan::__mapping_alike _StridedMapping> + requires (is_constructible_v<extents_type, + typename _StridedMapping::extents_type> + && _StridedMapping::is_always_unique() + && _StridedMapping::is_always_strided()) + constexpr explicit(!( + is_convertible_v<typename _StridedMapping::extents_type, extents_type> + && __mdspan::__standardized_mapping<_StridedMapping>)) + mapping(const _StridedMapping& __other) noexcept + : _M_extents(__other.extents()) + { + using _OIndexType = _StridedMapping::index_type; + using _OExtents = _StridedMapping::extents_type; + + __glibcxx_assert(__mdspan::__offset(__other) == 0); + static_assert(__mdspan::__representable_size<_OExtents, index_type>, + "The size of StridedMapping::extents_type must be representable as" + " index_type"); + if constexpr (cmp_greater(numeric_limits<_OIndexType>::max(), + numeric_limits<index_type>::max())) + __glibcxx_assert(!cmp_less(numeric_limits<index_type>::max(), + __other.required_span_size()) + && "other.required_span_size() must be representable" + " as index_type"); + if constexpr (extents_type::rank() > 0) + for (size_t __i = 0; __i < extents_type::rank(); ++__i) + _M_strides[__i] = index_type(__other.stride(__i)); + } + + constexpr mapping& + operator=(const mapping&) noexcept = default; + + constexpr const extents_type& + extents() const noexcept { return _M_extents; } + + constexpr array<index_type, extents_type::rank()> + strides() const noexcept + { + array<index_type, extents_type::rank()> __ret; + for (size_t __i = 0; __i < extents_type::rank(); ++__i) + __ret[__i] = _M_strides[__i]; + return __ret; + } + + constexpr index_type + required_span_size() const noexcept + { + if (__mdspan::__empty(_M_extents)) + return 0; + + index_type __ret = 1; + for (size_t __i = 0; __i < extents_type::rank(); ++__i) + __ret += (_M_extents.extent(__i) - 1) * _M_strides[__i]; + return __ret; + } + + template<__mdspan::__valid_index_type<index_type>... _Indices> + requires (sizeof...(_Indices) == extents_type::rank()) + constexpr index_type + operator()(_Indices... __indices) const noexcept + { + return __mdspan::__linear_index_strides(*this, + static_cast<index_type>(__indices)...); + } + + static constexpr bool + is_always_unique() noexcept { return true; } + + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 4266. layout_stride::mapping should treat empty mappings as exhaustive + static constexpr bool + is_always_exhaustive() noexcept + { + return (_Extents::rank() == 0) || __mdspan::__contains_zero( + __mdspan::__static_extents<extents_type>()); + } + + static constexpr bool + is_always_strided() noexcept { return true; } + + static constexpr bool + is_unique() noexcept { return true; } + + // _GLIBCXX_RESOLVE_LIB_DEFECTS + // 4266. layout_stride::mapping should treat empty mappings as exhaustive + constexpr bool + is_exhaustive() const noexcept + { + if constexpr (!is_always_exhaustive()) + { + constexpr auto __rank = extents_type::rank(); + auto __size = __mdspan::__fwd_prod(_M_extents, __rank); + if(__size > 0) + return __size == required_span_size(); + } + return true; + } + + static constexpr bool + is_strided() noexcept { return true; } + + constexpr index_type + stride(rank_type __r) const noexcept { return _M_strides[__r]; } + + template<__mdspan::__mapping_alike _OMapping> + requires ((extents_type::rank() == _OMapping::extents_type::rank()) + && _OMapping::is_always_strided()) + friend constexpr bool + operator==(const mapping& __self, const _OMapping& __other) noexcept + { + if (__self.extents() != __other.extents()) + return false; + if constexpr (extents_type::rank() > 0) + for (size_t __i = 0; __i < extents_type::rank(); ++__i) + if (!cmp_equal(__self.stride(__i), __other.stride(__i))) + return false; + return __mdspan::__offset(__other) == 0; + } + + private: + using _S_strides_t = typename __array_traits<index_type, + extents_type::rank()>::_Type; + [[no_unique_address]] extents_type _M_extents; + [[no_unique_address]] _S_strides_t _M_strides; + }; + _GLIBCXX_END_NAMESPACE_VERSION } #endif |