Tested on x86_64-pc-linux-gnu, does this look OK for trunk? libstdc++-v3/ChangeLog:
* include/std/ranges (as_rvalue_view): Define. (enable_borrowed_range<as_rvalue_view>): Define. (views::__detail::__can_as_rvalue_view): Define. (views::_AsRvalue, views::as_rvalue): Define. * testsuite/std/ranges/adaptors/as_rvalue/1.cc: New test. --- libstdc++-v3/include/std/ranges | 88 +++++++++++++++++++ .../std/ranges/adaptors/as_rvalue/1.cc | 47 ++++++++++ 2 files changed, 135 insertions(+) create mode 100644 libstdc++-v3/testsuite/std/ranges/adaptors/as_rvalue/1.cc diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges index 959886a1a55..239b3b61d30 100644 --- a/libstdc++-v3/include/std/ranges +++ b/libstdc++-v3/include/std/ranges @@ -8486,6 +8486,94 @@ namespace views::__adaptor inline constexpr _CartesianProduct cartesian_product; } + + template<input_range _Vp> + requires view<_Vp> + class as_rvalue_view : public view_interface<as_rvalue_view<_Vp>> + { + _Vp _M_base = _Vp(); + + public: + as_rvalue_view() requires default_initializable<_Vp> = default; + + constexpr explicit + as_rvalue_view(_Vp __base) + : _M_base(std::move(__base)) + { } + + constexpr _Vp + base() const& requires copy_constructible<_Vp> { return _M_base; } + + constexpr _Vp + base() && { return std::move(_M_base); } + + constexpr auto + begin() requires (!__detail::__simple_view<_Vp>) + { return move_iterator(ranges::begin(_M_base)); } + + constexpr auto + begin() const requires range<const _Vp> + { return move_iterator(ranges::begin(_M_base)); } + + constexpr auto + end() requires (!__detail::__simple_view<_Vp>) + { + if constexpr (common_range<_Vp>) + return move_iterator(ranges::end(_M_base)); + else + return move_sentinel(ranges::end(_M_base)); + } + + constexpr auto + end() const requires range<const _Vp> + { + if constexpr (common_range<const _Vp>) + return move_iterator(ranges::end(_M_base)); + else + return move_sentinel(ranges::end(_M_base)); + } + + constexpr auto + size() requires sized_range<_Vp> + { return ranges::size(_M_base); } + + constexpr auto + size() const requires sized_range<const _Vp> + { return ranges::size(_M_base); } + }; + + template<typename _Range> + as_rvalue_view(_Range&&) -> as_rvalue_view<views::all_t<_Range>>; + + template<typename _Tp> + inline constexpr bool enable_borrowed_range<as_rvalue_view<_Tp>> + = enable_borrowed_range<_Tp>; + + namespace views + { + namespace __detail + { + template<typename _Tp> + concept __can_as_rvalue_view = requires { as_rvalue_view(std::declval<_Tp>()); }; + } + + struct _AsRvalue : __adaptor::_RangeAdaptorClosure + { + template<viewable_range _Range> + requires __detail::__can_as_rvalue_view<_Range> + constexpr auto + operator() [[nodiscard]] (_Range&& __r) const + { + if constexpr (same_as<range_rvalue_reference_t<_Range>, + range_reference_t<_Range>>) + return views::all(std::forward<_Range>(__r)); + else + return as_rvalue_view(std::forward<_Range>(__r)); + } + }; + + inline constexpr _AsRvalue as_rvalue; + } #endif // C++23 } // namespace ranges diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/as_rvalue/1.cc b/libstdc++-v3/testsuite/std/ranges/adaptors/as_rvalue/1.cc new file mode 100644 index 00000000000..8ca4f50e9d2 --- /dev/null +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/as_rvalue/1.cc @@ -0,0 +1,47 @@ +// { dg-options "-std=gnu++23" } +// { dg-do run { target c++23 } } + +#include <ranges> +#include <algorithm> +#include <memory> +#include <testsuite_hooks.h> +#include <testsuite_iterators.h> + +namespace ranges = std::ranges; +namespace views = std::views; + +constexpr bool +test01() +{ + + std::unique_ptr<int> a[3] = { std::make_unique<int>(1), + std::make_unique<int>(2), + std::make_unique<int>(3) }; + std::unique_ptr<int> b[3]; + auto v = a | views::as_rvalue; + ranges::copy(v, b); + VERIFY( ranges::all_of(a, [](auto& p) { return p.get() == nullptr; }) ); + VERIFY( ranges::equal(b | views::transform([](auto& p) { return *p; }), (int[]){1, 2, 3}) ); + + return true; +} + +void +test02() +{ + std::unique_ptr<int> x = std::make_unique<int>(42); + std::unique_ptr<int> y; + __gnu_test::test_input_range rx(&x, &x+1); + auto v = rx | views::as_rvalue; + static_assert(!ranges::common_range<decltype(v)>); + ranges::copy(v, &y); + VERIFY( x.get() == nullptr ); + VERIFY( *y == 42 ); +} + +int +main() +{ + static_assert(test01()); + test02(); +} -- 2.38.1.381.gc03801e19c