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libstdc++: Implement ranges::repeat_view from P2474R2
libstdc++-v3/ChangeLog: * include/std/ranges (repeat_view): Define. (repeat_view::_Iterator): Define. (views::__detail::__can_repeat_view): Define. (views::__detail::__can_bounded_repeat_view): Define. (views::_Repeat, views::repeat): Define. * testsuite/std/ranges/repeat/1.cc: New test.
This commit is contained in:
Patrick Palka
@@ -7356,6 +7356,216 @@ namespace views::__adaptor
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inline constexpr _JoinWith join_with;
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} // namespace views
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template<copy_constructible _Tp, semiregular _Bound = unreachable_sentinel_t>
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requires (is_object_v<_Tp> && same_as<_Tp, remove_cv_t<_Tp>>
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&& (__detail::__is_integer_like<_Bound> || same_as<_Bound, unreachable_sentinel_t>))
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class repeat_view : public view_interface<repeat_view<_Tp, _Bound>>
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{
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__detail::__box<_Tp> _M_value = _Tp();
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[[no_unique_address]] _Bound _M_bound = _Bound();
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struct _Iterator;
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public:
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repeat_view() requires default_initializable<_Tp> = default;
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constexpr explicit
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repeat_view(const _Tp& __value, _Bound __bound = _Bound())
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: _M_value(__value), _M_bound(__bound)
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{
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if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
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__glibcxx_assert(__bound >= 0);
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}
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constexpr explicit
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repeat_view(_Tp&& __value, _Bound __bound = _Bound())
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: _M_value(std::move(__value)), _M_bound(__bound)
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{ }
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template<typename... _Args, typename... _BoundArgs>
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requires constructible_from<_Tp, _Args...>
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&& constructible_from<_Bound, _BoundArgs...>
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constexpr explicit
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repeat_view(piecewise_construct_t,
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tuple<_Args...> __args,
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tuple<_BoundArgs...> __bound_args = tuple<>{})
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: _M_value(std::make_from_tuple<_Tp>(std::move(__args))),
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_M_bound(std::make_from_tuple<_Bound>(std::move(__bound_args)))
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{ }
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constexpr _Iterator
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begin() const
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{ return _Iterator(std::__addressof(*_M_value)); }
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constexpr _Iterator
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end() const requires (!same_as<_Bound, unreachable_sentinel_t>)
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{ return _Iterator(std::__addressof(*_M_value), _M_bound); }
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constexpr unreachable_sentinel_t
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end() const noexcept
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{ return unreachable_sentinel; }
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constexpr auto
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size() const requires (!same_as<_Bound, unreachable_sentinel_t>)
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{ return __detail::__to_unsigned_like(_M_bound); }
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};
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template<typename _Tp, typename _Bound>
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repeat_view(_Tp, _Bound) -> repeat_view<_Tp, _Bound>;
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template<copy_constructible _Tp, semiregular _Bound>
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requires __detail::__is_integer_like<_Bound> || same_as<_Bound, unreachable_sentinel_t>
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class repeat_view<_Tp, _Bound>::_Iterator
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{
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using __index_type
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= __conditional_t<same_as<_Bound, unreachable_sentinel_t>, ptrdiff_t, _Bound>;
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const _Tp* _M_value = nullptr;
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__index_type _M_current = __index_type();
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constexpr explicit
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_Iterator(const _Tp* __value, __index_type __bound = __index_type())
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: _M_value(__value), _M_current(__bound)
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{
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if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
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__glibcxx_assert(__bound >= 0);
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}
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friend repeat_view;
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public:
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using iterator_concept = random_access_iterator_tag;
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using iterator_category = random_access_iterator_tag;
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using value_type = _Tp;
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using difference_type = __conditional_t<__detail::__is_signed_integer_like<__index_type>,
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__index_type,
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__detail::__iota_diff_t<__index_type>>;
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_Iterator() = default;
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constexpr const _Tp&
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operator*() const noexcept
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{ return *_M_value; }
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constexpr _Iterator&
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operator++()
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{
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++_M_current;
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return *this;
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}
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constexpr _Iterator
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operator++(int)
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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--()
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{
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if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
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__glibcxx_assert(_M_current > 0);
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--_M_current;
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return *this;
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}
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constexpr _Iterator
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operator--(int)
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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)
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{
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if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
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__glibcxx_assert(_M_current + __n >= 0);
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_M_current += __n;
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return *this;
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}
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constexpr _Iterator&
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operator-=(difference_type __n)
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{
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if constexpr (!same_as<_Bound, unreachable_sentinel_t>)
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__glibcxx_assert(_M_current - __n >= 0);
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_M_current -= __n;
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return *this;
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}
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constexpr const _Tp&
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operator[](difference_type __n) const noexcept
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{ return *(*this + __n); }
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friend constexpr bool
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operator==(const _Iterator& __x, const _Iterator& __y)
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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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{ return __x._M_current <=> __y._M_current; }
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friend constexpr _Iterator
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operator+(_Iterator __i, difference_type __n)
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{
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__i += __n;
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return __i;
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}
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friend constexpr _Iterator
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operator+(difference_type __n, _Iterator __i)
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{ return __i + __n; }
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friend constexpr _Iterator
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operator-(_Iterator __i, difference_type __n)
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{
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__i -= __n;
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return __i;
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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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{
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return (static_cast<difference_type>(__x._M_current)
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- static_cast<difference_type>(__y._M_current));
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}
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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 _Tp>
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concept __can_repeat_view
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= requires { repeat_view(std::declval<_Tp>()); };
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template<typename _Tp, typename _Bound>
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concept __can_bounded_repeat_view
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= requires { repeat_view(std::declval<_Tp>(), std::declval<_Bound>()); };
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}
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struct _Repeat
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{
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template<typename _Tp>
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requires __detail::__can_repeat_view<_Tp>
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constexpr auto
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operator() [[nodiscard]] (_Tp&& __value) const
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{ return repeat_view(std::forward<_Tp>(__value)); }
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template<typename _Tp, typename _Bound>
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requires __detail::__can_bounded_repeat_view<_Tp, _Bound>
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constexpr auto
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operator() [[nodiscard]] (_Tp&& __value, _Bound __bound) const
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{ return repeat_view(std::forward<_Tp>(__value), __bound); }
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};
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inline constexpr _Repeat repeat;
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}
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#endif // C++23
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} // namespace ranges
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93
libstdc++-v3/testsuite/std/ranges/repeat/1.cc
Normal file
93
libstdc++-v3/testsuite/std/ranges/repeat/1.cc
Normal file
@@ -0,0 +1,93 @@
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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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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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auto v = views::repeat(42);
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static_assert(ranges::random_access_range<decltype(v)>
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&& !ranges::sized_range<decltype(v)>);
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auto i = ranges::begin(v);
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auto s = ranges::end(v);
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VERIFY( *i == 42 );
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VERIFY( i[0] == 42 );
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VERIFY( &i[0] == &i[1] );
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VERIFY( &*i == &*(i+1) );
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VERIFY( i != s );
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auto j = i + 5, k = i + 12;
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VERIFY( k - i == 12 );
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VERIFY( k - j == 7 );
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VERIFY( i - j == -5 );
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VERIFY( k > j );
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VERIFY( j < k );
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VERIFY( i + 5 == j );
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VERIFY( i != j );
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VERIFY( i + 5 <= j );
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VERIFY( j - 5 >= i );
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return true;
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}
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constexpr bool
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test02()
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{
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constexpr int bound = 20;
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auto v = views::repeat(42, bound);
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static_assert(ranges::random_access_range<decltype(v)>
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&& ranges::sized_range<decltype(v)>);
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VERIFY( ranges::equal(v, views::repeat(42) | views::take(bound)) );
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auto i = ranges::begin(v);
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auto s = ranges::end(v);
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VERIFY( *i == 42 );
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VERIFY( i[0] == 42 );
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VERIFY( &i[0] == &i[1] );
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VERIFY( &*i == &*(i+1) );
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VERIFY( i != s );
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auto j = i + 5, k = i + 12;
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VERIFY( k - i == 12 );
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VERIFY( k - j == 7 );
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VERIFY( i - j == -5 );
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VERIFY( k > j );
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VERIFY( j < k );
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VERIFY( i + 5 == j );
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VERIFY( i != j );
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VERIFY( i + 5 <= j );
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VERIFY( j - 5 >= i );
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VERIFY( ranges::size(v) == bound );
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VERIFY( s - i == bound );
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VERIFY( s - j == bound - (j - i) );
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VERIFY( i + bound == s );
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VERIFY( bound + i == s );
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return true;
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}
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constexpr bool
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test03()
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{
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struct A { int n, m; };
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auto v = ranges::repeat_view<A, unsigned>(std::piecewise_construct,
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std::tuple{1, 2},
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std::tuple{3});
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VERIFY( v[0].n == 1 );
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VERIFY( v[0].m == 2 );
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VERIFY( ranges::size(v) == 3 );
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return true;
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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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static_assert(test02());
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static_assert(test03());
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}
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