libstdc++: Implement ranges::stride_view from P1899R3
libstdc++-v3/ChangeLog: * include/std/ranges (stride_view): Define. (stride_view::_Iterator): Define. (views::__detail::__can_stride_view): Define. (views::_Stride, views::stride): Define. * testsuite/std/ranges/adaptors/stride/1.cc: New test.
This commit is contained in:
Patrick Palka
parent
3b3083a598
commit
c70b44f2c1
2 changed files with 424 additions and 0 deletions
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@ -7566,6 +7566,357 @@ namespace views::__adaptor
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inline constexpr _Repeat repeat;
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}
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template<input_range _Vp>
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requires view<_Vp>
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class stride_view : public view_interface<stride_view<_Vp>>
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{
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_Vp _M_base;
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range_difference_t<_Vp> _M_stride;
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template<bool _Const> using _Base = __detail::__maybe_const_t<_Const, _Vp>;
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template<bool _Const>
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struct __iter_cat
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{ };
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template<bool _Const>
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requires forward_range<_Base<_Const>>
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struct __iter_cat<_Const>
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{
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private:
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static auto
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_S_iter_cat()
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{
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using _Cat = typename iterator_traits<iterator_t<_Base<_Const>>>::iterator_category;
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if constexpr (derived_from<_Cat, random_access_iterator_tag>)
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return random_access_iterator_tag{};
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else
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return _Cat{};
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}
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public:
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using iterator_category = decltype(_S_iter_cat());
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};
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template<bool> class _Iterator;
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public:
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constexpr explicit
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stride_view(_Vp __base, range_difference_t<_Vp> __stride)
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: _M_base(std::move(__base)), _M_stride(__stride)
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{ __glibcxx_assert(__stride > 0); }
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constexpr _Vp
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base() const& requires copy_constructible<_Vp>
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{ return _M_base; }
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constexpr _Vp
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base() &&
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{ return std::move(_M_base); }
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constexpr range_difference_t<_Vp>
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stride() const noexcept
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{ return _M_stride; }
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constexpr auto
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begin() requires (!__detail::__simple_view<_Vp>)
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{ return _Iterator<false>(this, ranges::begin(_M_base)); }
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constexpr auto
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begin() const requires range<const _Vp>
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{ return _Iterator<true>(this, ranges::begin(_M_base)); }
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constexpr auto
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end() requires (!__detail::__simple_view<_Vp>)
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{
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if constexpr (common_range<_Vp> && sized_range<_Vp> && forward_range<_Vp>)
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{
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auto __missing = (_M_stride - ranges::distance(_M_base) % _M_stride) % _M_stride;
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return _Iterator<false>(this, ranges::end(_M_base), __missing);
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}
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else if constexpr (common_range<_Vp> && !bidirectional_range<_Vp>)
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return _Iterator<false>(this, ranges::end(_M_base));
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else
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return default_sentinel;
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}
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constexpr auto
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end() const requires range<const _Vp>
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{
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if constexpr (common_range<const _Vp> && sized_range<const _Vp>
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&& forward_range<const _Vp>)
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{
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auto __missing = (_M_stride - ranges::distance(_M_base) % _M_stride) % _M_stride;
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return _Iterator<true>(this, ranges::end(_M_base), __missing);
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}
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else if constexpr (common_range<const _Vp> && !bidirectional_range<const _Vp>)
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return _Iterator<true>(this, ranges::end(_M_base));
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else
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return default_sentinel;
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}
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constexpr auto
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size() requires sized_range<_Vp>
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{
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return __detail::__to_unsigned_like
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(__detail::__div_ceil(ranges::distance(_M_base), _M_stride));
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}
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constexpr auto
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size() const requires sized_range<const _Vp>
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{
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return __detail::__to_unsigned_like
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(__detail::__div_ceil(ranges::distance(_M_base), _M_stride));
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}
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};
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template<typename _Range>
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stride_view(_Range&&, range_difference_t<_Range>) -> stride_view<views::all_t<_Range>>;
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template<typename _Vp>
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inline constexpr bool enable_borrowed_range<stride_view<_Vp>>
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= enable_borrowed_range<_Vp>;
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template<input_range _Vp>
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requires view<_Vp>
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template<bool _Const>
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class stride_view<_Vp>::_Iterator : public __iter_cat<_Const>
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{
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using _Parent = __detail::__maybe_const_t<_Const, stride_view>;
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using _Base = stride_view::_Base<_Const>;
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iterator_t<_Base> _M_current = iterator_t<_Base>();
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sentinel_t<_Base> _M_end = sentinel_t<_Base>();
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range_difference_t<_Base> _M_stride = 0;
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range_difference_t<_Base> _M_missing = 0;
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constexpr
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_Iterator(_Parent* __parent, iterator_t<_Base> __current,
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range_difference_t<_Base> __missing = 0)
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: _M_current(std::move(__current)), _M_end(ranges::end(__parent->_M_base)),
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_M_stride(__parent->_M_stride), _M_missing(__missing)
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{ }
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static auto
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_S_iter_concept()
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{
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if constexpr (random_access_range<_Base>)
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return random_access_iterator_tag{};
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else if constexpr (bidirectional_range<_Base>)
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return bidirectional_iterator_tag{};
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else if constexpr (forward_range<_Base>)
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return forward_iterator_tag{};
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else
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return input_iterator_tag{};
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}
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friend stride_view;
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public:
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using difference_type = range_difference_t<_Base>;
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using value_type = range_value_t<_Base>;
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using iterator_concept = decltype(_S_iter_concept());
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// iterator_category defined in stride_view::__iter_cat
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_Iterator() requires default_initializable<iterator_t<_Base>> = default;
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constexpr
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_Iterator(_Iterator<!_Const> __other)
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requires _Const
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&& convertible_to<iterator_t<_Vp>, iterator_t<_Base>>
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&& convertible_to<sentinel_t<_Vp>, sentinel_t<_Base>>
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: _M_current(std::move(__other._M_current)), _M_end(std::move(__other._M_end)),
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_M_stride(__other._M_stride), _M_missing(__other._M_missing)
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{ }
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constexpr iterator_t<_Base>
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base() &&
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{ return std::move(_M_current); }
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constexpr const iterator_t<_Base>&
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base() const & noexcept
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{ return _M_current; }
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constexpr decltype(auto)
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operator*() const
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{ return *_M_current; }
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constexpr _Iterator&
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operator++()
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{
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__glibcxx_assert(_M_current != _M_end);
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_M_missing = ranges::advance(_M_current, _M_stride, _M_end);
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return *this;
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}
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constexpr void
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operator++(int)
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{ ++*this; }
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constexpr _Iterator
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operator++(int) requires forward_range<_Base>
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{
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auto __tmp = *this;
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++*this;
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return __tmp;
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}
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constexpr _Iterator&
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operator--() requires bidirectional_range<_Base>
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{
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ranges::advance(_M_current, _M_missing - _M_stride);
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_M_missing = 0;
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return *this;
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}
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constexpr _Iterator
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operator--(int) requires bidirectional_range<_Base>
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{
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auto __tmp = *this;
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--*this;
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return __tmp;
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}
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constexpr _Iterator&
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operator+=(difference_type __n) requires random_access_range<_Base>
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{
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if (__n > 0)
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{
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__glibcxx_assert(ranges::distance(_M_current, _M_end) > _M_stride * (__n - 1));
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_M_missing = ranges::advance(_M_current, _M_stride * __n, _M_end);
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}
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else if (__n < 0)
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{
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ranges::advance(_M_current, _M_stride * __n + _M_missing);
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_M_missing = 0;
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}
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return *this;
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}
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constexpr _Iterator&
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operator-=(difference_type __n) requires random_access_range<_Base>
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{ return *this += -__n; }
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constexpr decltype(auto) operator[](difference_type __n) const
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requires random_access_range<_Base>
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{ return *(*this + __n); }
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friend constexpr bool
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operator==(const _Iterator& __x, default_sentinel_t)
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{ return __x._M_current == __x._M_end; }
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friend constexpr bool
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operator==(const _Iterator& __x, const _Iterator& __y)
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requires equality_comparable<iterator_t<_Base>>
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{ return __x._M_current == __y._M_current; }
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friend constexpr bool
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operator<(const _Iterator& __x, const _Iterator& __y)
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requires random_access_range<_Base>
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{ return __x._M_current < __y._M_current; }
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friend constexpr bool
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operator>(const _Iterator& __x, const _Iterator& __y)
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requires random_access_range<_Base>
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{ return __y._M_current < __x._M_current; }
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friend constexpr bool
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operator<=(const _Iterator& __x, const _Iterator& __y)
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requires random_access_range<_Base>
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{ return !(__y._M_current < __x._M_current); }
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friend constexpr bool
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operator>=(const _Iterator& __x, const _Iterator& __y)
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requires random_access_range<_Base>
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{ return !(__x._M_current < __y._M_current); }
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friend constexpr auto
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operator<=>(const _Iterator& __x, const _Iterator& __y)
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requires random_access_range<_Base> && three_way_comparable<iterator_t<_Base>>
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{ return __x._M_current <=> __y._M_current; }
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friend constexpr _Iterator
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operator+(const _Iterator& __i, difference_type __n)
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requires random_access_range<_Base>
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{
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auto __r = __i;
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__r += __n;
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return __r;
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}
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friend constexpr _Iterator
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operator+(difference_type __n, const _Iterator& __i)
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requires random_access_range<_Base>
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{ return __i + __n; }
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friend constexpr _Iterator
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operator-(const _Iterator& __i, difference_type __n)
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requires random_access_range<_Base>
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{
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auto __r = __i;
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__r -= __n;
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return __r;
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}
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friend constexpr difference_type
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operator-(const _Iterator& __x, const _Iterator& __y)
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requires sized_sentinel_for<iterator_t<_Base>, iterator_t<_Base>>
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{
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auto __n = __x._M_current - __y._M_current;
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if constexpr (forward_range<_Base>)
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return (__n + __x._M_missing - __y._M_missing) / __x._M_stride;
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else if (__n < 0)
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return -__detail::__div_ceil(-__n, __x._M_stride);
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else
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return __detail::__div_ceil(__n, __x._M_stride);
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}
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friend constexpr difference_type
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operator-(default_sentinel_t __y, const _Iterator& __x)
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requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base>>
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{ return __detail::__div_ceil(__x._M_end, __x._M_current, __x._M_stride); }
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friend constexpr difference_type
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operator-(const _Iterator& __x, default_sentinel_t __y)
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requires sized_sentinel_for<sentinel_t<_Base>, iterator_t<_Base>>
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{ return -(__y - __x); }
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friend constexpr range_rvalue_reference_t<_Base>
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iter_move(const _Iterator& __i)
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noexcept(noexcept(ranges::iter_move(__i._M_current)))
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{ return ranges::iter_move(__i._M_current); }
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friend constexpr void
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iter_swap(const _Iterator& __x, const _Iterator& __y)
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noexcept(noexcept(ranges::iter_swap(__x._M_current, __y._M_current)))
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requires indirectly_swappable<iterator_t<_Base>>
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{ ranges::iter_swap(__x._M_current, __y._M_current); }
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};
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namespace views
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{
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namespace __detail
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{
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template<typename _Range, typename _Dp>
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concept __can_stride_view
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= requires { stride_view(std::declval<_Range>(), std::declval<_Dp>()); };
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}
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struct _Stride : __adaptor::_RangeAdaptor<_Stride>
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{
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template<viewable_range _Range, typename _Dp = range_difference_t<_Range>>
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requires __detail::__can_stride_view<_Range, _Dp>
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constexpr auto
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operator() [[nodiscard]] (_Range&& __r, type_identity_t<_Dp> __n) const
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{ return stride_view(std::forward<_Range>(__r), __n); }
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using __adaptor::_RangeAdaptor<_Stride>::operator();
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static constexpr int _S_arity = 2;
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static constexpr bool _S_has_simple_extra_args = true;
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};
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inline constexpr _Stride stride;
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}
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#endif // C++23
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} // namespace ranges
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73
libstdc++-v3/testsuite/std/ranges/adaptors/stride/1.cc
Normal file
73
libstdc++-v3/testsuite/std/ranges/adaptors/stride/1.cc
Normal file
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@ -0,0 +1,73 @@
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// { dg-options "-std=gnu++23" }
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// { dg-do run { target c++23 } }
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#include <ranges>
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#include <algorithm>
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#include <testsuite_hooks.h>
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#include <testsuite_iterators.h>
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namespace ranges = std::ranges;
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namespace views = std::views;
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constexpr bool
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test01()
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{
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int x[] = {1, 2, 3, 4, 5, 6, 7};
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auto v2 = x | views::stride(2);
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const auto i0 = v2.begin(), i1 = v2.begin() + 1;
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VERIFY( i0 + 1 - 1 == i0 );
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VERIFY( i0 != i1 );
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VERIFY( i0 < i1 );
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VERIFY( i0 <= i0 );
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VERIFY( i0 >= i0 );
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VERIFY( v2.end() > i1 );
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VERIFY( i1 - i0 == 1 );
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VERIFY( i0 - i1 == -1 );
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VERIFY( v2.end() - i1 == 3 );
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VERIFY( i1 - v2.end() == -3 );
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auto i2 = v2.begin();
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i2 += 2;
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i2 -= -2;
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VERIFY( i2 == v2.end() );
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VERIFY( ranges::size(v2) == 4 );
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VERIFY( ranges::equal(v2, (int[]){1, 3, 5, 7}) );
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VERIFY( ranges::equal(v2 | views::reverse, (int[]){7, 5, 3, 1}) );
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VERIFY( v2.stride() == 2 );
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auto v1 = x | views::stride(1);
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VERIFY( ranges::size(v1) == ranges::size(x) );
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VERIFY( ranges::equal(v1, x) );
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VERIFY( ranges::equal(v1 | views::reverse, x | views::reverse) );
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VERIFY( v1.stride() == 1 );
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auto v5 = x | views::stride(5);
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VERIFY( ranges::equal(v5, (int[]){1, 6}) );
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VERIFY( ranges::equal(v5 | views::reverse, (int[]){6, 1}) );
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VERIFY( v5.stride() == 5 );
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auto v10 = x | views::stride(10);
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VERIFY( ranges::equal(v10, (int[]){1}) );
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VERIFY( ranges::equal(v10 | views::reverse, (int[]){1}) );
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VERIFY( v10.stride() == 10 );
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return true;
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}
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template<class container>
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void
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test02()
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{
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int x[] = {1, 2, 3, 4, 5, 6, 7, 8};
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container rx(x);
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auto v = rx | views::stride(3);
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VERIFY( ranges::equal(v, (int[]){1, 4, 7}) );
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}
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int
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main()
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{
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static_assert(test01());
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test02<__gnu_test::test_input_range<int>>();
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test02<__gnu_test::test_forward_range<int>>();
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}
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