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b65bdd27fd
* include/std/span: Do not include <tuple> and <utility>. (tuple_size, tuple_element): Declare. From-SVN: r279171
485 lines
14 KiB
C++
485 lines
14 KiB
C++
// Components for manipulating non-owning sequences of objects -*- C++ -*-
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// Copyright (C) 2019 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file span
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* This is a Standard C++ Library header.
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*/
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//
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// P0122 span library
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// Contributed by ThePhD
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//
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#ifndef _GLIBCXX_SPAN
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#define _GLIBCXX_SPAN 1
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#pragma GCC system_header
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#if __cplusplus > 201703L
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#include <type_traits>
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#include <array>
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#include <bits/stl_iterator.h>
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#include <bits/range_access.h>
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#if __cpp_lib_concepts
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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#define __cpp_lib_span 201902L
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inline constexpr size_t dynamic_extent = static_cast<size_t>(-1);
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template<typename _Type, size_t _Extent>
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class span;
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namespace __detail
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{
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template<typename _Tp>
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struct __is_std_span : false_type { };
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template<typename _Tp, size_t _Num>
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struct __is_std_span<span<_Tp, _Num>> : true_type { };
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template<typename _Tp>
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struct __is_std_array : false_type { };
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template<typename _Tp, size_t _Num>
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struct __is_std_array<_GLIBCXX_STD_C::array<_Tp, _Num>> : true_type { };
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#ifdef _GLIBCXX_DEBUG
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template<typename _Tp, size_t _Num>
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struct __is_std_array<__debug::array<_Tp, _Num>> : true_type { };
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#endif
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template<size_t _Extent>
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class __extent_storage
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{
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public:
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constexpr
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__extent_storage(size_t) noexcept
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{ }
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static constexpr size_t
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_M_extent() noexcept
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{ return _Extent; }
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};
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template<>
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class __extent_storage<dynamic_extent>
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{
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public:
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constexpr
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__extent_storage(size_t __extent) noexcept
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: _M_extent_value(__extent)
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{ }
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constexpr size_t
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_M_extent() const noexcept
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{ return this->_M_extent_value; }
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private:
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size_t _M_extent_value;
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};
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} // namespace __detail
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template<typename _Type, size_t _Extent = dynamic_extent>
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class span
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{
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template<size_t _Offset, size_t _Count>
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static constexpr size_t
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_S_subspan_extent()
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{
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if constexpr (_Count != dynamic_extent)
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return _Count;
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else if constexpr (extent != dynamic_extent)
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return _Extent - _Offset;
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else
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return dynamic_extent;
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}
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 3255. span's array constructor is too strict
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template<typename _Tp, size_t _ArrayExtent>
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using __is_compatible_array = __and_<
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bool_constant<(_Extent == dynamic_extent || _ArrayExtent == _Extent)>,
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__is_array_convertible<_Type, _Tp>>;
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template<typename _Iter, typename _Ref = iter_reference_t<_Iter>>
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using __is_compatible_iterator = __and_<
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bool_constant<contiguous_iterator<_Iter>>,
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is_lvalue_reference<iter_reference_t<_Iter>>,
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is_same<iter_value_t<_Iter>, remove_cvref_t<_Ref>>,
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__is_array_convertible<_Type, remove_reference_t<_Ref>>>;
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template<typename _Range>
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using __is_compatible_range
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= __is_compatible_iterator<ranges::iterator_t<_Range>>;
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public:
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// member types
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using value_type = remove_cv_t<_Type>;
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using element_type = _Type;
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using size_type = size_t;
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using reference = element_type&;
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using const_reference = const element_type&;
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using pointer = _Type*;
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using const_pointer = const _Type*;
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using iterator
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= __gnu_cxx::__normal_iterator<pointer, span>;
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using const_iterator
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= __gnu_cxx::__normal_iterator<const_pointer, span>;
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using reverse_iterator = std::reverse_iterator<iterator>;
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using const_reverse_iterator = std::reverse_iterator<const_iterator>;
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using difference_type = ptrdiff_t;
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// member constants
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static inline constexpr size_t extent = _Extent;
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// constructors
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constexpr
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span() noexcept
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requires ((_Extent + 1u) <= 1u)
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: _M_extent(0), _M_ptr(nullptr)
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{ }
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constexpr
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span(const span&) noexcept = default;
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template<typename _Tp, size_t _ArrayExtent>
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requires (__is_compatible_array<_Tp, _ArrayExtent>::value)
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constexpr
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span(_Tp (&__arr)[_ArrayExtent]) noexcept
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: span(static_cast<pointer>(__arr), _ArrayExtent)
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{ }
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template<typename _Tp, size_t _ArrayExtent>
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requires (__is_compatible_array<_Tp, _ArrayExtent>::value)
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constexpr
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span(array<_Tp, _ArrayExtent>& __arr) noexcept
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: span(static_cast<pointer>(__arr.data()), _ArrayExtent)
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{ }
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template<typename _Tp, size_t _ArrayExtent>
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requires (__is_compatible_array<const _Tp, _ArrayExtent>::value)
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constexpr
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span(const array<_Tp, _ArrayExtent>& __arr) noexcept
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: span(static_cast<pointer>(__arr.data()), _ArrayExtent)
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{ }
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public:
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template<ranges::contiguous_range _Range>
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requires (_Extent == dynamic_extent)
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&& (!__detail::__is_std_span<remove_cvref_t<_Range>>::value)
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&& (!__detail::__is_std_array<remove_cvref_t<_Range>>::value)
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&& (!is_array_v<remove_reference_t<_Range>>)
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&& (__is_compatible_range<_Range>::value)
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constexpr
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span(_Range&& __range)
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noexcept(noexcept(ranges::data(__range))
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&& noexcept(ranges::size(__range)))
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: span(ranges::data(__range), ranges::size(__range))
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{ }
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template<contiguous_iterator _ContiguousIterator,
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sized_sentinel_for<_ContiguousIterator> _Sentinel>
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requires (__is_compatible_iterator<_ContiguousIterator>::value)
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&& (!is_convertible_v<_Sentinel, size_type>)
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constexpr
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span(_ContiguousIterator __first, _Sentinel __last)
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: _M_extent(static_cast<size_type>(__last - __first)),
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_M_ptr(std::to_address(__first))
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{
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if (_Extent != dynamic_extent)
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__glibcxx_assert((__last - __first) == _Extent);
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}
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template<contiguous_iterator _ContiguousIterator>
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requires (__is_compatible_iterator<_ContiguousIterator>::value)
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constexpr
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span(_ContiguousIterator __first, size_type __count)
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noexcept(noexcept(std::to_address(__first)))
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: _M_extent(__count), _M_ptr(std::to_address(__first))
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{ __glibcxx_assert(_Extent == dynamic_extent || __count == _Extent); }
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template<typename _OType, size_t _OExtent>
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requires (_Extent == dynamic_extent || _Extent == _OExtent)
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&& (__is_array_convertible<_Type, _OType>::value)
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constexpr
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span(const span<_OType, _OExtent>& __s) noexcept
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: _M_extent(__s.size()), _M_ptr(__s.data())
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{ }
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// assignment
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constexpr span&
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operator=(const span&) noexcept = default;
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// observers
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constexpr size_type
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size() const noexcept
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{ return this->_M_extent._M_extent(); }
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constexpr size_type
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size_bytes() const noexcept
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{ return this->_M_extent._M_extent() * sizeof(element_type); }
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[[nodiscard]] constexpr bool
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empty() const noexcept
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{ return size() == 0; }
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// element access
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constexpr reference
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front() const noexcept
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{
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static_assert(extent != 0);
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__glibcxx_assert(!empty());
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return *this->_M_ptr;
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}
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constexpr reference
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back() const noexcept
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{
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static_assert(extent != 0);
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__glibcxx_assert(!empty());
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return *(this->_M_ptr + (size() - 1));
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}
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constexpr reference
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operator[](size_type __idx) const noexcept
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{
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static_assert(extent != 0);
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__glibcxx_assert(__idx < size());
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return *(this->_M_ptr + __idx);
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}
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constexpr pointer
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data() const noexcept
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{ return this->_M_ptr; }
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// iterator support
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constexpr iterator
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begin() const noexcept
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{ return iterator(this->_M_ptr); }
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constexpr const_iterator
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cbegin() const noexcept
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{ return const_iterator(this->_M_ptr); }
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constexpr iterator
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end() const noexcept
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{ return iterator(this->_M_ptr + this->size()); }
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constexpr const_iterator
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cend() const noexcept
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{ return const_iterator(this->_M_ptr + this->size()); }
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constexpr reverse_iterator
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rbegin() const noexcept
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{ return reverse_iterator(this->end()); }
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constexpr const_reverse_iterator
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crbegin() const noexcept
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{ return const_reverse_iterator(this->cend()); }
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constexpr reverse_iterator
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rend() const noexcept
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{ return reverse_iterator(this->begin()); }
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constexpr const_reverse_iterator
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crend() const noexcept
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{ return const_reverse_iterator(this->cbegin()); }
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// subviews
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template<size_t _Count>
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constexpr span<element_type, _Count>
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first() const noexcept
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{
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if constexpr (_Extent == dynamic_extent)
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__glibcxx_assert(_Count <= size());
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else
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static_assert(_Count <= extent);
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return { this->data(), _Count };
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}
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constexpr span<element_type, dynamic_extent>
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first(size_type __count) const noexcept
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{
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__glibcxx_assert(__count <= size());
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return { this->data(), __count };
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}
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template<size_t _Count>
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constexpr span<element_type, _Count>
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last() const noexcept
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{
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if constexpr (_Extent == dynamic_extent)
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__glibcxx_assert(_Count <= size());
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else
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static_assert(_Count <= extent);
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return { this->data() + (this->size() - _Count), _Count };
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}
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constexpr span<element_type, dynamic_extent>
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last(size_type __count) const noexcept
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{
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__glibcxx_assert(__count <= size());
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return { this->data() + (this->size() - __count), __count };
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}
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template<size_t _Offset, size_t _Count = dynamic_extent>
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constexpr auto
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subspan() const noexcept
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-> span<element_type, _S_subspan_extent<_Offset, _Count>()>
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{
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if constexpr (_Extent == dynamic_extent)
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__glibcxx_assert(_Offset <= size());
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else
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static_assert(_Offset <= extent);
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if constexpr (_Count == dynamic_extent)
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return { this->data() + _Offset, this->size() - _Offset };
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else
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{
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if constexpr (_Extent == dynamic_extent)
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{
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__glibcxx_assert(_Count <= size());
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__glibcxx_assert(_Count <= (size() - _Offset));
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}
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else
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{
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static_assert(_Count <= extent);
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static_assert(_Count <= (extent - _Offset));
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}
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return { this->data() + _Offset, _Count };
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}
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}
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constexpr span<element_type, dynamic_extent>
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subspan(size_type __offset, size_type __count = dynamic_extent) const
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noexcept
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{
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__glibcxx_assert(__offset <= size());
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if (__count == dynamic_extent)
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__count = this->size() - __offset;
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else
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{
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__glibcxx_assert(__count <= size());
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__glibcxx_assert(__offset + __count <= size());
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}
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return {this->data() + __offset, __count};
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}
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private:
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[[no_unique_address]] __detail::__extent_storage<extent> _M_extent;
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pointer _M_ptr;
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};
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// deduction guides
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template<typename _Type, size_t _ArrayExtent>
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span(_Type(&)[_ArrayExtent]) -> span<_Type, _ArrayExtent>;
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template<typename _Type, size_t _ArrayExtent>
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span(array<_Type, _ArrayExtent>&) -> span<_Type, _ArrayExtent>;
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template<typename _Type, size_t _ArrayExtent>
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span(const array<_Type, _ArrayExtent>&)
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-> span<const _Type, _ArrayExtent>;
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template<contiguous_iterator _Iter, typename _Sentinel>
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span(_Iter, _Sentinel)
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-> span<remove_reference_t<ranges::range_reference_t<_Iter>>>;
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template<typename _Range>
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span(_Range &&)
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-> span<remove_reference_t<ranges::range_reference_t<_Range&>>>;
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template<typename _Type, size_t _Extent>
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inline
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span<const byte, _Extent == dynamic_extent
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? dynamic_extent : _Extent * sizeof(_Type)>
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as_bytes(span<_Type, _Extent> __sp) noexcept
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{
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return {reinterpret_cast<const byte*>(__sp.data()), __sp.size_bytes()};
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}
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template<typename _Type, size_t _Extent>
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inline
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span<byte, _Extent == dynamic_extent
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? dynamic_extent : _Extent * sizeof(_Type)>
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as_writable_bytes(span<_Type, _Extent> __sp) noexcept
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{
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return {reinterpret_cast<byte*>(__sp.data()), __sp.size_bytes()};
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}
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// tuple helpers
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template<size_t _Index, typename _Type, size_t _Extent>
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constexpr _Type&
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get(span<_Type, _Extent> __sp) noexcept
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{
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static_assert(_Extent != dynamic_extent && _Index < _Extent,
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"get<I> can only be used with a span of non-dynamic (fixed) extent");
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return __sp[_Index];
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}
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template<typename _Tp> struct tuple_size;
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template<size_t __i, typename _Tp> struct tuple_element;
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template<typename _Type, size_t _Extent>
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struct tuple_size<span<_Type, _Extent>>
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: public integral_constant<size_t, _Extent>
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{
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static_assert(_Extent != dynamic_extent, "tuple_size can only "
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"be used with a span of non-dynamic (fixed) extent");
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};
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template<size_t _Index, typename _Type, size_t _Extent>
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struct tuple_element<_Index, span<_Type, _Extent>>
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{
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static_assert(_Extent != dynamic_extent, "tuple_element can only "
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"be used with a span of non-dynamic (fixed) extent");
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static_assert(_Index < _Extent, "Index is less than Extent");
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using type = _Type;
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};
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namespace ranges
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{
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template<typename> extern inline const bool enable_safe_range;
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// Opt-in to safe_range concept
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template<typename _ElementType, size_t _Extent>
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inline constexpr bool
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enable_safe_range<span<_ElementType, _Extent>> = true;
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}
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace std
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#endif // concepts
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#endif // C++20
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#endif // _GLIBCXX_SPAN
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