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++/ChangeLog:
* include/std/mdspan (layout_right): New class.
Signed-off-by: Luc Grosheintz <luc.groshei...@gmail.com>
---
libstdc++-v3/include/std/mdspan | 147 ++++++++++++++++++++++++++++++++
1 file changed, 147 insertions(+)
diff --git a/libstdc++-v3/include/std/mdspan b/libstdc++-v3/include/std/mdspan
index e05048a5b93..583792b5269 100644
--- a/libstdc++-v3/include/std/mdspan
+++ b/libstdc++-v3/include/std/mdspan
@@ -330,6 +330,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
class mapping;
};
+ struct layout_right
+ {
+ template<typename _Extents>
+ class mapping;
+ };
+
namespace __mdspan
{
template<typename _Tp>
@@ -427,6 +433,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
: _M_extents(__other.extents())
{ }
+ 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
+ : _M_extents(__other.extents())
+ { }
+
constexpr mapping&
operator=(const mapping&) noexcept = default;
@@ -483,6 +497,139 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
[[no_unique_address]] extents_type _M_extents;
};
+ namespace __mdspan
+ {
+ template<size_t _Count>
+ struct _LinearIndexRight
+ {
+ template<typename _Extents>
+ static constexpr typename _Extents::index_type
+ _S_value(typename _Extents::index_type __accumulated,
+ const _Extents&) noexcept
+ { return __accumulated; }
+
+ template<typename _Extents, typename... _Indices>
+ static constexpr typename _Extents::index_type
+ _S_value(typename _Extents::index_type __accumulated,
+ const _Extents& __exts, typename _Extents::index_type __idx,
+ _Indices... __indices) noexcept
+ {
+ // (...) * __exts[r-1] + __indices[r-1];
+ return _LinearIndexRight<_Count + 1>::_S_value(
+ __accumulated * __exts.extent(_Count) + __idx, __exts,
+ __indices...);
+ }
+ };
+
+ template<typename _Extents, typename... _Indices>
+ constexpr typename _Extents::index_type
+ __linear_index_right(const _Extents& __exts, _Indices... __indices)
+ {
+ return _LinearIndexRight<0>::_S_value(0, __exts, __indices...);
+ }
+ }
+
+ template<typename _Extents>
+ class layout_right::mapping
+ {
+ static_assert(__mdspan::__layout_extent<_Extents>,
+ "The size of extents_type is not representable as index_type.");
+ 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;
+
+ constexpr
+ mapping() noexcept = default;
+
+ constexpr
+ mapping(const mapping&) noexcept = default;
+
+ constexpr
+ mapping(const extents_type& __extents) noexcept
+ : _M_extents(__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
+ : _M_extents(__other.extents())
+ { }
+
+ 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
+ : _M_extents(__other.extents())
+ { }
+
+ 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, _M_extents.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:
+ [[no_unique_address]] _Extents _M_extents;
+ };
+
_GLIBCXX_END_NAMESPACE_VERSION
}
#endif
--
2.49.0
