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|
// <mdspan> -*- C++ -*-
// Copyright The GNU Toolchain Authors.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/** @file mdspan
* This is a Standard C++ Library header.
*/
#ifndef _GLIBCXX_MDSPAN
#define _GLIBCXX_MDSPAN 1
#ifdef _GLIBCXX_SYSHDR
#pragma GCC system_header
#endif
#include <span>
#include <array>
#include <type_traits>
#include <limits>
#include <utility>
#define __glibcxx_want_mdspan
#include <bits/version.h>
#ifdef __glibcxx_mdspan
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
namespace __mdspan
{
template<typename _IndexType, array _Extents>
class _ExtentsStorage
{
public:
static consteval bool
_S_is_dyn(size_t __ext) noexcept
{ return __ext == dynamic_extent; }
template<typename _OIndexType>
static constexpr _IndexType
_S_int_cast(const _OIndexType& __other) noexcept
{ return _IndexType(__other); }
static constexpr size_t _S_rank = _Extents.size();
// For __r in [0, _S_rank], _S_dynamic_index[__r] is the number
// of dynamic extents up to (and not including) __r.
//
// If __r is the index of a dynamic extent, then
// _S_dynamic_index[__r] is the index of that extent in
// _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)
{
__ret[__i] = __dyn;
__dyn += _S_is_dyn(_Extents[__i]);
}
__ret[_S_rank] = __dyn;
return __ret;
}();
static constexpr size_t _S_rank_dynamic = _S_dynamic_index[_S_rank];
// For __r in [0, _S_rank_dynamic), _S_dynamic_index_inv[__r] is the
// index of the __r-th dynamic extent in _Extents.
static constexpr auto _S_dynamic_index_inv = [] consteval
{
array<size_t, _S_rank_dynamic> __ret;
for (size_t __i = 0, __r = 0; __i < _S_rank; ++__i)
if (_S_is_dyn(_Extents[__i]))
__ret[__r++] = __i;
return __ret;
}();
static constexpr size_t
_S_static_extent(size_t __r) noexcept
{ return _Extents[__r]; }
constexpr _IndexType
_M_extent(size_t __r) const noexcept
{
auto __se = _Extents[__r];
if (__se == dynamic_extent)
return _M_dyn_exts[_S_dynamic_index[__r]];
else
return __se;
}
template<size_t _OtherRank, typename _GetOtherExtent>
constexpr void
_M_init_dynamic_extents(_GetOtherExtent __get_extent) noexcept
{
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_dyn_exts[__i] = _S_int_cast(__get_extent(__di));
}
}
constexpr
_ExtentsStorage() noexcept = default;
template<typename _OIndexType, array _OExtents>
constexpr
_ExtentsStorage(const _ExtentsStorage<_OIndexType, _OExtents>&
__other) noexcept
{
_M_init_dynamic_extents<_S_rank>([&__other](size_t __i)
{ return __other._M_extent(__i); });
}
template<typename _OIndexType, size_t _Nm>
constexpr
_ExtentsStorage(span<const _OIndexType, _Nm> __exts) noexcept
{
_M_init_dynamic_extents<_Nm>(
[&__exts](size_t __i) -> const _OIndexType&
{ 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_dyn_exts{};
};
template<typename _OIndexType, typename _SIndexType>
concept __valid_index_type =
is_convertible_v<_OIndexType, _SIndexType> &&
is_nothrow_constructible_v<_SIndexType, _OIndexType>;
template<size_t _Extent, typename _IndexType>
concept
__valid_static_extent = _Extent == dynamic_extent
|| _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
{
static_assert(__is_standard_integer<_IndexType>::value,
"IndexType must be a signed or unsigned integer type");
static_assert(
(__mdspan::__valid_static_extent<_Extents, _IndexType> && ...),
"Extents must either be dynamic or representable as IndexType");
public:
using index_type = _IndexType;
using size_type = make_unsigned_t<index_type>;
using rank_type = size_t;
static constexpr rank_type
rank() noexcept { return _S_storage::_S_rank; }
static constexpr rank_type
rank_dynamic() noexcept { return _S_storage::_S_rank_dynamic; }
static constexpr size_t
static_extent(rank_type __r) noexcept
{
__glibcxx_assert(__r < rank());
if constexpr (rank() == 0)
__builtin_trap();
else
return _S_storage::_S_static_extent(__r);
}
constexpr index_type
extent(rank_type __r) const noexcept
{
__glibcxx_assert(__r < rank());
if constexpr (rank() == 0)
__builtin_trap();
else
return _M_exts._M_extent(__r);
}
constexpr
extents() noexcept = default;
private:
static consteval bool
_S_is_less_dynamic(size_t __ext, size_t __oext)
{ return (__ext != dynamic_extent) && (__oext == dynamic_extent); }
template<typename _OIndexType, size_t... _OExtents>
static consteval bool
_S_ctor_explicit()
{
return (_S_is_less_dynamic(_Extents, _OExtents) || ...)
|| (numeric_limits<index_type>::max()
< numeric_limits<_OIndexType>::max());
}
template<size_t... _OExtents>
static consteval bool
_S_is_compatible_extents()
{
if constexpr (sizeof...(_OExtents) != rank())
return false;
else
return ((_OExtents == dynamic_extent || _Extents == dynamic_extent
|| _OExtents == _Extents) && ...);
}
public:
template<typename _OIndexType, size_t... _OExtents>
requires (_S_is_compatible_extents<_OExtents...>())
constexpr explicit(_S_ctor_explicit<_OIndexType, _OExtents...>())
extents(const extents<_OIndexType, _OExtents...>& __other) noexcept
: _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_exts(span<const _IndexType, sizeof...(_OIndexTypes)>(
initializer_list{_S_storage::_S_int_cast(__exts)...}))
{ }
template<__mdspan::__valid_index_type<index_type> _OIndexType, size_t _Nm>
requires (_Nm == rank() || _Nm == rank_dynamic())
constexpr explicit(_Nm != rank_dynamic())
extents(span<_OIndexType, _Nm> __exts) noexcept
: _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_exts(span<const _OIndexType, _Nm>(__exts))
{ }
template<typename _OIndexType, size_t... _OExtents>
friend constexpr bool
operator==(const extents& __self,
const extents<_OIndexType, _OExtents...>& __other) noexcept
{
if constexpr (!_S_is_compatible_extents<_OExtents...>())
return false;
else
{
for (size_t __i = 0; __i < __self.rank(); ++__i)
if (!cmp_equal(__self.extent(__i), __other.extent(__i)))
return false;
return true;
}
}
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_exts;
template<typename _OIndexType, size_t... _OExtents>
friend class extents;
};
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)...>;
template<typename _Tp>
consteval size_t
__dynamic_extent() { return dynamic_extent; }
}
template<typename _IndexType, size_t _Rank>
using dextents = decltype(__mdspan::__build_dextents_type<_IndexType>(
make_index_sequence<_Rank>()));
template<typename... _Integrals>
requires (is_convertible_v<_Integrals, size_t> && ...)
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
#endif
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