582c57a17e
Also fix the constraints on span(Container&) and span(const Container&) constructors so that they aren't used for const spans or const arrays. * include/std/span (span(element_type(&)[N])) (span(array<value_type, N>&), span(const array<value_type, N>&)): Deduce array element type to allow safe const conversions (LWG 3255). [!_GLIBCXX_P1394] (span(Container&), span(const Container&)): Use remove_cv_t on arguments to __is_std_span and __is_std_array. * testsuite/23_containers/span/lwg3255.cc: New test. From-SVN: r276298
580 lines
17 KiB
C++
580 lines
17 KiB
C++
// Components for manipulating non-owning sequences of objects -*- C++ -*-
|
|
|
|
// Copyright (C) 2019 Free Software Foundation, Inc.
|
|
//
|
|
// 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 span
|
|
* This is a Standard C++ Library header.
|
|
*/
|
|
|
|
//
|
|
// P0122 span library
|
|
// Contributed by ThePhD
|
|
//
|
|
|
|
#ifndef _GLIBCXX_SPAN
|
|
#define _GLIBCXX_SPAN 1
|
|
|
|
#pragma GCC system_header
|
|
|
|
#if __cplusplus > 201703L
|
|
|
|
#include <type_traits>
|
|
#include <tuple>
|
|
#include <utility>
|
|
#include <array>
|
|
#include <bits/stl_iterator.h>
|
|
#include <bits/range_access.h>
|
|
|
|
namespace std _GLIBCXX_VISIBILITY(default)
|
|
{
|
|
_GLIBCXX_BEGIN_NAMESPACE_VERSION
|
|
|
|
#define __cpp_lib_span 201902L
|
|
|
|
inline constexpr size_t dynamic_extent = static_cast<size_t>(-1);
|
|
|
|
template<typename _Type, size_t _Extent>
|
|
class span;
|
|
|
|
namespace __detail
|
|
{
|
|
template<typename _Tp>
|
|
struct __is_std_span : false_type { };
|
|
|
|
template<typename _Tp, size_t _Num>
|
|
struct __is_std_span<span<_Tp, _Num>> : true_type { };
|
|
|
|
template<typename _Tp>
|
|
struct __is_std_array : false_type { };
|
|
|
|
template<typename _Tp, size_t _Num>
|
|
struct __is_std_array<_GLIBCXX_STD_C::array<_Tp, _Num>> : true_type { };
|
|
|
|
#ifdef _GLIBCXX_DEBUG
|
|
template<typename _Tp, size_t _Num>
|
|
struct __is_std_array<__debug::array<_Tp, _Num>> : true_type { };
|
|
#endif
|
|
|
|
template<size_t _Extent>
|
|
class __extent_storage
|
|
{
|
|
public:
|
|
constexpr
|
|
__extent_storage(size_t) noexcept
|
|
{ }
|
|
|
|
static constexpr size_t
|
|
_M_extent() noexcept
|
|
{ return _Extent; }
|
|
};
|
|
|
|
template<>
|
|
class __extent_storage<dynamic_extent>
|
|
{
|
|
public:
|
|
constexpr
|
|
__extent_storage(size_t __extent) noexcept
|
|
: _M_extent_value(__extent)
|
|
{ }
|
|
|
|
constexpr size_t
|
|
_M_extent() const noexcept
|
|
{ return this->_M_extent_value; }
|
|
|
|
private:
|
|
size_t _M_extent_value;
|
|
};
|
|
|
|
} // namespace __detail
|
|
|
|
template<typename _Type, size_t _Extent = dynamic_extent>
|
|
class span
|
|
{
|
|
template<size_t _Offset, size_t _Count>
|
|
static constexpr size_t
|
|
_S_subspan_extent()
|
|
{
|
|
if constexpr (_Count != dynamic_extent)
|
|
return _Count;
|
|
else if constexpr (extent != dynamic_extent)
|
|
return _Extent - _Offset;
|
|
else
|
|
return dynamic_extent;
|
|
}
|
|
|
|
template<typename _Tp>
|
|
using __is_compatible = is_convertible<_Tp(*)[], _Type(*)[]>;
|
|
|
|
// _GLIBCXX_RESOLVE_LIB_DEFECTS
|
|
// 3255. span's array constructor is too strict
|
|
template<typename _Tp, size_t _ArrayExtent,
|
|
typename = enable_if_t<_Extent == dynamic_extent
|
|
|| _ArrayExtent == _Extent>>
|
|
using __is_compatible_array = __is_compatible<_Tp>;
|
|
|
|
public:
|
|
// member types
|
|
using value_type = remove_cv_t<_Type>;
|
|
using element_type = _Type;
|
|
using index_type = size_t;
|
|
using reference = element_type&;
|
|
using const_reference = const element_type&;
|
|
using pointer = _Type*;
|
|
using const_pointer = const _Type*;
|
|
using iterator
|
|
= __gnu_cxx::__normal_iterator<pointer, span>;
|
|
using const_iterator
|
|
= __gnu_cxx::__normal_iterator<const_pointer, span>;
|
|
using reverse_iterator = std::reverse_iterator<iterator>;
|
|
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
|
|
using difference_type = ptrdiff_t;
|
|
// Official wording has no size_type -- why??
|
|
// using size_type = size_t;
|
|
|
|
// member constants
|
|
static inline constexpr size_t extent = _Extent;
|
|
|
|
// constructors
|
|
|
|
template<bool _DefaultConstructible = (_Extent + 1u) <= 1u,
|
|
enable_if_t<_DefaultConstructible>* = nullptr>
|
|
constexpr
|
|
span() noexcept : _M_extent(0), _M_ptr(nullptr)
|
|
{ }
|
|
|
|
constexpr
|
|
span(const span&) noexcept = default;
|
|
|
|
template<typename _Tp, size_t _ArrayExtent,
|
|
typename = _Require<__is_compatible_array<_Tp, _ArrayExtent>>>
|
|
constexpr
|
|
span(_Tp (&__arr)[_ArrayExtent]) noexcept
|
|
: span(static_cast<pointer>(__arr), _ArrayExtent)
|
|
{ }
|
|
|
|
template<typename _Tp, size_t _ArrayExtent,
|
|
typename = _Require<__is_compatible_array<_Tp, _ArrayExtent>>>
|
|
constexpr
|
|
span(array<_Tp, _ArrayExtent>& __arr) noexcept
|
|
: span(static_cast<pointer>(__arr.data()), _ArrayExtent)
|
|
{ }
|
|
|
|
template<typename _Tp, size_t _ArrayExtent,
|
|
typename = _Require<__is_compatible_array<_Tp, _ArrayExtent>>>
|
|
constexpr
|
|
span(const array<_Tp, _ArrayExtent>& __arr) noexcept
|
|
: span(static_cast<pointer>(__arr.data()), _ArrayExtent)
|
|
{ }
|
|
|
|
// NOTE: when the time comes, and P1394 -
|
|
// range constructors for std::span - ships in
|
|
// the standard, delete the #else block and remove
|
|
// the conditional
|
|
// if the paper fails, delete #if block
|
|
// and keep the crappy #else block
|
|
// and then cry that NB comments failed C++20...
|
|
// but maybe for C++23?
|
|
#ifdef _GLIBCXX_P1394
|
|
private:
|
|
// FIXME: use std::iter_reference_t
|
|
template<typename _Iterator>
|
|
using iter_reference_t = decltype(*std::declval<_Iterator&>());
|
|
// FIXME: use std::ranges::iterator_t
|
|
// N.B. constraint is needed to prevent a cycle when __adl_begin finds
|
|
// begin(span) which does overload resolution on span(Range&&).
|
|
template<typename _Rng,
|
|
typename _Rng2 = remove_cvref_t<_Rng>,
|
|
typename = enable_if_t<!__detail::__is_std_span<_Rng2>::value>>
|
|
using iterator_t = decltype(std::__adl_begin(std::declval<_Rng&>()));
|
|
// FIXME: use std::iter_value_t
|
|
template<typename _Iter>
|
|
using iter_value_t = typename iterator_traits<_Iter>::value_type;
|
|
// FIXME: use std::derived_from concept
|
|
template<typename _Derived, typename _Base>
|
|
using derived_from
|
|
= __and_<is_base_of<_Base, _Derived>,
|
|
is_convertible<const volatile _Derived*, const volatile _Base*>>;
|
|
// FIXME: require contiguous_iterator<_Iterator>
|
|
template<typename _Iter,
|
|
typename _Ref = iter_reference_t<_Iter>,
|
|
typename _Traits = iterator_traits<_Iter>,
|
|
typename _Tag = typename _Traits::iterator_category>
|
|
using __is_compatible_iterator
|
|
= __and_<derived_from<_Tag, random_access_iterator_tag>,
|
|
is_lvalue_reference<_Ref>,
|
|
is_same<iter_value_t<_Iter>, remove_cvref_t<_Ref>>,
|
|
__is_compatible<remove_reference_t<_Ref>>>;
|
|
|
|
template<typename _Range>
|
|
using __is_compatible_range
|
|
= __is_compatible_iterator<iterator_t<_Range>>;
|
|
|
|
public:
|
|
template<typename _Range, typename = _Require<
|
|
bool_constant<_Extent == dynamic_extent>,
|
|
__not_<__detail::__is_std_span<remove_cvref_t<_Range>>>,
|
|
__not_<__detail::__is_std_array<remove_cvref_t<_Range>>>,
|
|
__not_<is_array<remove_reference_t<_Range>>>,
|
|
__is_compatible_range<_Range>>,
|
|
typename = decltype(std::__adl_data(std::declval<_Range&>()))>
|
|
constexpr
|
|
span(_Range&& __range)
|
|
noexcept(noexcept(::std::__adl_data(__range))
|
|
&& noexcept(::std::__adl_size(__range)))
|
|
: span(::std::__adl_data(__range), ::std::__adl_size(__range))
|
|
{ }
|
|
|
|
template<typename _ContiguousIterator, typename _Sentinel, typename
|
|
= _Require<__not_<is_convertible<_Sentinel, index_type>>,
|
|
__is_compatible_iterator<_ContiguousIterator>>>
|
|
constexpr
|
|
span(_ContiguousIterator __first, _Sentinel __last)
|
|
: _M_extent(static_cast<index_type>(__last - __first)),
|
|
_M_ptr(std::to_address(__first))
|
|
{
|
|
if (_Extent != dynamic_extent)
|
|
__glibcxx_assert((__last - __first) == _Extent);
|
|
}
|
|
|
|
template<typename _ContiguousIterator, typename
|
|
= _Require<__is_compatible_iterator<_ContiguousIterator>>>
|
|
constexpr
|
|
span(_ContiguousIterator __first, index_type __count)
|
|
noexcept(noexcept(std::to_address(__first)))
|
|
: _M_extent(__count), _M_ptr(std::to_address(__first))
|
|
{ __glibcxx_assert(_Extent == dynamic_extent || __count == _Extent); }
|
|
#else
|
|
private:
|
|
template<typename _Container,
|
|
typename _DataT = decltype(std::data(std::declval<_Container&>())),
|
|
typename _SizeT = decltype(std::size(std::declval<_Container&>()))>
|
|
using __is_compatible_container
|
|
= __is_compatible<remove_pointer_t<_DataT>>;
|
|
|
|
public:
|
|
template<typename _Container, typename = _Require<
|
|
bool_constant<_Extent == dynamic_extent>,
|
|
__not_<__detail::__is_std_span<remove_cv_t<_Container>>>,
|
|
__not_<__detail::__is_std_array<remove_cv_t<_Container>>>,
|
|
__not_<is_array<_Container>>,
|
|
__is_compatible_container<_Container>>>
|
|
constexpr
|
|
span(_Container& __cont)
|
|
noexcept(noexcept(std::data(__cont)) && noexcept(std::size(__cont)))
|
|
: _M_extent(std::size(__cont)), _M_ptr(std::data(__cont))
|
|
{ }
|
|
|
|
template<typename _Container, typename = _Require<
|
|
bool_constant<_Extent == dynamic_extent>,
|
|
__not_<__detail::__is_std_span<remove_cv_t<_Container>>>,
|
|
__not_<__detail::__is_std_array<remove_cv_t<_Container>>>,
|
|
__not_<is_array<_Container>>,
|
|
__is_compatible_container<const _Container>>>
|
|
constexpr
|
|
span(const _Container& __cont)
|
|
noexcept(noexcept(std::data(__cont)) && noexcept(std::size(__cont)))
|
|
: _M_extent(std::size(__cont)), _M_ptr(std::data(__cont))
|
|
{ }
|
|
|
|
constexpr
|
|
span(pointer __first, index_type __count) noexcept
|
|
: _M_extent(__count), _M_ptr(__first)
|
|
{ __glibcxx_assert(_Extent == dynamic_extent || __count == _Extent); }
|
|
|
|
constexpr
|
|
span(pointer __first, pointer __last) noexcept
|
|
: span(__first, static_cast<index_type>(__last - __first))
|
|
{ }
|
|
#endif // P1394
|
|
|
|
template<typename _OType, size_t _OExtent, typename = _Require<
|
|
__bool_constant<_Extent == dynamic_extent || _Extent == _OExtent>,
|
|
is_convertible<_OType(*)[], _Type(*)[]>>>
|
|
constexpr
|
|
span(const span<_OType, _OExtent>& __s) noexcept
|
|
: _M_extent(__s.size()), _M_ptr(__s.data())
|
|
{ }
|
|
|
|
// assignment
|
|
|
|
constexpr span&
|
|
operator=(const span&) noexcept = default;
|
|
|
|
// observers
|
|
|
|
constexpr index_type
|
|
size() const noexcept
|
|
{ return this->_M_extent._M_extent(); }
|
|
|
|
constexpr index_type
|
|
size_bytes() const noexcept
|
|
{ return this->_M_extent._M_extent() * sizeof(element_type); }
|
|
|
|
[[nodiscard]] constexpr bool
|
|
empty() const noexcept
|
|
{ return size() == 0; }
|
|
|
|
// element access
|
|
|
|
constexpr reference
|
|
front() const noexcept
|
|
{
|
|
static_assert(extent != 0);
|
|
__glibcxx_assert(!empty());
|
|
return *this->_M_ptr;
|
|
}
|
|
|
|
constexpr reference
|
|
back() const noexcept
|
|
{
|
|
static_assert(extent != 0);
|
|
__glibcxx_assert(!empty());
|
|
return *(this->_M_ptr + (size() - 1));
|
|
}
|
|
|
|
constexpr reference
|
|
operator[](index_type __idx) const noexcept
|
|
{
|
|
static_assert(extent != 0);
|
|
__glibcxx_assert(__idx < size());
|
|
return *(this->_M_ptr + __idx);
|
|
}
|
|
|
|
constexpr pointer
|
|
data() const noexcept
|
|
{ return this->_M_ptr; }
|
|
|
|
// iterator support
|
|
|
|
constexpr iterator
|
|
begin() const noexcept
|
|
{ return iterator(this->_M_ptr); }
|
|
|
|
constexpr const_iterator
|
|
cbegin() const noexcept
|
|
{ return const_iterator(this->_M_ptr); }
|
|
|
|
constexpr iterator
|
|
end() const noexcept
|
|
{ return iterator(this->_M_ptr + this->size()); }
|
|
|
|
constexpr const_iterator
|
|
cend() const noexcept
|
|
{ return const_iterator(this->_M_ptr + this->size()); }
|
|
|
|
constexpr reverse_iterator
|
|
rbegin() const noexcept
|
|
{ return reverse_iterator(this->end()); }
|
|
|
|
constexpr const_reverse_iterator
|
|
crbegin() const noexcept
|
|
{ return const_reverse_iterator(this->cend()); }
|
|
|
|
constexpr reverse_iterator
|
|
rend() const noexcept
|
|
{ return reverse_iterator(this->begin()); }
|
|
|
|
constexpr const_reverse_iterator
|
|
crend() const noexcept
|
|
{ return const_reverse_iterator(this->cbegin()); }
|
|
|
|
// subviews
|
|
|
|
template<size_t _Count>
|
|
constexpr span<element_type, _Count>
|
|
first() const noexcept
|
|
{
|
|
if constexpr (_Extent == dynamic_extent)
|
|
__glibcxx_assert(_Count <= size());
|
|
else
|
|
static_assert(_Count <= extent);
|
|
return { this->data(), _Count };
|
|
}
|
|
|
|
constexpr span<element_type, dynamic_extent>
|
|
first(index_type __count) const noexcept
|
|
{
|
|
__glibcxx_assert(__count <= size());
|
|
return { this->data(), __count };
|
|
}
|
|
|
|
template<size_t _Count>
|
|
constexpr span<element_type, _Count>
|
|
last() const noexcept
|
|
{
|
|
if constexpr (_Extent == dynamic_extent)
|
|
__glibcxx_assert(_Count <= size());
|
|
else
|
|
static_assert(_Count <= extent);
|
|
return { this->data() + (this->size() - _Count), _Count };
|
|
}
|
|
|
|
constexpr span<element_type, dynamic_extent>
|
|
last(index_type __count) const noexcept
|
|
{
|
|
__glibcxx_assert(__count <= size());
|
|
return { this->data() + (this->size() - __count), __count };
|
|
}
|
|
|
|
template<size_t _Offset, size_t _Count = dynamic_extent>
|
|
constexpr auto
|
|
subspan() const noexcept
|
|
-> span<element_type, _S_subspan_extent<_Offset, _Count>()>
|
|
{
|
|
if constexpr (_Extent == dynamic_extent)
|
|
__glibcxx_assert(_Offset <= size());
|
|
else
|
|
static_assert(_Offset <= extent);
|
|
|
|
if constexpr (_Count == dynamic_extent)
|
|
return { this->data() + _Offset, this->size() - _Offset };
|
|
else
|
|
{
|
|
if constexpr (_Extent == dynamic_extent)
|
|
{
|
|
__glibcxx_assert(_Count <= size());
|
|
__glibcxx_assert(_Count <= (size() - _Offset));
|
|
}
|
|
else
|
|
{
|
|
static_assert(_Count <= extent);
|
|
static_assert(_Count <= (extent - _Offset));
|
|
}
|
|
return { this->data() + _Offset, _Count };
|
|
}
|
|
}
|
|
|
|
constexpr span<element_type, dynamic_extent>
|
|
subspan(index_type __offset, index_type __count = dynamic_extent) const
|
|
noexcept
|
|
{
|
|
__glibcxx_assert(__offset <= size());
|
|
if (__count == dynamic_extent)
|
|
__count = this->size() - __offset;
|
|
else
|
|
{
|
|
__glibcxx_assert(__count <= size());
|
|
__glibcxx_assert(__offset + __count <= size());
|
|
}
|
|
return {this->data() + __offset, __count};
|
|
}
|
|
|
|
// observers: range helpers
|
|
|
|
friend constexpr iterator
|
|
begin(span __sp) noexcept
|
|
{ return __sp.begin(); }
|
|
|
|
friend constexpr iterator
|
|
end(span __sp) noexcept
|
|
{ return __sp.end(); }
|
|
|
|
private:
|
|
[[no_unique_address]] __detail::__extent_storage<extent> _M_extent;
|
|
pointer _M_ptr;
|
|
};
|
|
|
|
// deduction guides
|
|
template<typename _Type, size_t _ArrayExtent>
|
|
span(_Type(&)[_ArrayExtent]) -> span<_Type, _ArrayExtent>;
|
|
|
|
template<typename _Type, size_t _ArrayExtent>
|
|
span(array<_Type, _ArrayExtent>&) -> span<_Type, _ArrayExtent>;
|
|
|
|
template<typename _Type, size_t _ArrayExtent>
|
|
span(const array<_Type, _ArrayExtent>&)
|
|
-> span<const _Type, _ArrayExtent>;
|
|
|
|
#ifdef _GLIBCXX_P1394
|
|
|
|
template<typename _ContiguousIterator, typename _Sentinel>
|
|
span(_ContiguousIterator, _Sentinel)
|
|
-> span<remove_reference_t<
|
|
typename iterator_traits<_ContiguousIterator>::reference>>;
|
|
|
|
template<typename _Range>
|
|
span(_Range &&)
|
|
-> span<remove_reference_t<typename iterator_traits<
|
|
decltype(std::__adl_begin(::std::declval<_Range&>()))>::reference>>;
|
|
|
|
#else
|
|
|
|
template<typename _Container>
|
|
span(_Container&) -> span<typename _Container::value_type>;
|
|
|
|
template<typename _Container>
|
|
span(const _Container&) -> span<const typename _Container::value_type>;
|
|
|
|
#endif // P1394
|
|
|
|
template<typename _Type, size_t _Extent>
|
|
inline
|
|
span<const byte, _Extent == dynamic_extent
|
|
? dynamic_extent : _Extent * sizeof(_Type)>
|
|
as_bytes(span<_Type, _Extent> __sp) noexcept
|
|
{
|
|
return {reinterpret_cast<const byte*>(__sp.data()), __sp.size_bytes()};
|
|
}
|
|
|
|
template<typename _Type, size_t _Extent>
|
|
inline
|
|
span<byte, _Extent == dynamic_extent
|
|
? dynamic_extent : _Extent * sizeof(_Type)>
|
|
as_writable_bytes(span<_Type, _Extent> __sp) noexcept
|
|
{
|
|
return {reinterpret_cast<byte*>(__sp.data()), __sp.size_bytes()};
|
|
}
|
|
|
|
// tuple helpers
|
|
template<size_t _Index, typename _Type, size_t _Extent>
|
|
constexpr _Type&
|
|
get(span<_Type, _Extent> __sp) noexcept
|
|
{
|
|
static_assert(_Extent != dynamic_extent && _Index < _Extent,
|
|
"get<I> can only be used with a span of non-dynamic (fixed) extent");
|
|
return __sp[_Index];
|
|
}
|
|
|
|
template<typename _Type, size_t _Extent>
|
|
struct tuple_size<span<_Type, _Extent>>
|
|
: public integral_constant<size_t, _Extent>
|
|
{
|
|
static_assert(_Extent != dynamic_extent, "tuple_size can only "
|
|
"be used with a span of non-dynamic (fixed) extent");
|
|
};
|
|
|
|
template<size_t _Index, typename _Type, size_t _Extent>
|
|
struct tuple_element<_Index, span<_Type, _Extent>>
|
|
{
|
|
static_assert(_Extent != dynamic_extent, "tuple_element can only "
|
|
"be used with a span of non-dynamic (fixed) extent");
|
|
static_assert(_Index < _Extent, "Index is less than Extent");
|
|
using type = _Type;
|
|
};
|
|
|
|
_GLIBCXX_END_NAMESPACE_VERSION
|
|
} // namespace std
|
|
|
|
#endif // C++20
|
|
#endif // _GLIBCXX_SPAN
|