Implement the parts of layout_left that depend on layout_right; and the
parts of layout_right that don't depend on layout_stride.
libstdc++-v3/ChangeLog:
* include/std/mdspan (layout_right): New class.
Signed-off-by: Luc Grosheintz <luc.groshei...@gmail.com>
---
libstdc++-v3/include/std/mdspan | 153 +++++++++++++++++++++++++++++++-
1 file changed, 152 insertions(+), 1 deletion(-)
diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan
index d90fed57a19..13ed27bcaaf 100644
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -390,6 +390,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
class mapping;
};
+ struct layout_right
+ {
+ template<typename _Extents>
+ class mapping;
+ };
+
namespace __mdspan
{
template<typename _Tp>
@@ -494,7 +500,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Mapping>;
template<typename _Mapping>
- concept __standardized_mapping = __mapping_of<layout_left, _Mapping>;
+ concept __standardized_mapping = __mapping_of<layout_left, _Mapping>
+ || __mapping_of<layout_right, _Mapping>;
template<typename M>
concept __mapping_like = requires
@@ -544,6 +551,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: mapping(__other.extents(), __mdspan::__internal_ctor{})
{ }
+ template<typename _OExtents>
+ requires (_Extents::rank() <= 1
+ && is_constructible_v<_Extents, _OExtents>)
+ constexpr explicit(!is_convertible_v<_OExtents, _Extents>)
+ mapping(const layout_right::mapping<_OExtents>& __other) noexcept
+ : mapping(__other.extents(), __mdspan::__internal_ctor{})
+ { }
+
constexpr mapping&
operator=(const mapping&) noexcept = default;
@@ -611,6 +626,142 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
[[no_unique_address]] _Extents _M_extents;
};
+ namespace __mdspan
+ {
+ template<typename _Extents, typename... _Indices>
+ constexpr typename _Extents::index_type
+ __linear_index_right(const _Extents& __exts, _Indices... __indices)
+ {
+ 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, 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& __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<class _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{})
+ { }
+
+ constexpr mapping&
+ operator=(const mapping&) noexcept = default;
+
+ constexpr const _Extents&
+ 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(extents_type(__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));
+ }
+
+ public:
+ [[no_unique_address]] _Extents _M_extents;
+ };
+
_GLIBCXX_END_NAMESPACE_VERSION
}
#endif
--
2.49.0
