On Mon, 14 Nov 2022 at 04:51, Patrick Palka via Libstdc++
<libstd...@gcc.gnu.org> wrote:
>
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/ranges_algo.h (__find_last_fn, find_last):
> Define.
> (__find_last_if_fn, find_last_if): Define.
> (__find_last_if_not_fn, find_last_if_not): Define.
> * testsuite/25_algorithms/find_last/1.cc: New test.
> * testsuite/25_algorithms/find_last_if/1.cc: New test.
> * testsuite/25_algorithms/find_last_if_not/1.cc: New test.
> ---
> libstdc++-v3/include/bits/ranges_algo.h | 123 ++++++++++++++++++
> .../testsuite/25_algorithms/find_last/1.cc | 90 +++++++++++++
> .../testsuite/25_algorithms/find_last_if/1.cc | 92 +++++++++++++
> .../25_algorithms/find_last_if_not/1.cc | 92 +++++++++++++
> 4 files changed, 397 insertions(+)
> create mode 100644 libstdc++-v3/testsuite/25_algorithms/find_last/1.cc
> create mode 100644 libstdc++-v3/testsuite/25_algorithms/find_last_if/1.cc
> create mode 100644 libstdc++-v3/testsuite/25_algorithms/find_last_if_not/1.cc
>
> diff --git a/libstdc++-v3/include/bits/ranges_algo.h
> b/libstdc++-v3/include/bits/ranges_algo.h
> index f003117c569..0e4329382eb 100644
> --- a/libstdc++-v3/include/bits/ranges_algo.h
> +++ b/libstdc++-v3/include/bits/ranges_algo.h
> @@ -3565,6 +3565,129 @@ namespace ranges
> };
>
> inline constexpr __iota_fn iota{};
> +
> + struct __find_last_fn
> + {
> + template<forward_iterator _Iter, sentinel_for<_Iter> _Sent, typename T,
> typename _Proj = identity>
> + requires indirect_binary_predicate<ranges::equal_to, projected<_Iter,
> _Proj>, const T*>
> + constexpr subrange<_Iter>
> + operator()(_Iter __first, _Sent __last, const T& __value, _Proj __proj
> = {}) const
> + {
> + if constexpr (same_as<_Iter, _Sent> && bidirectional_iterator<_Iter>)
> + {
> + _Iter __found = ranges::find(reverse_iterator<_Iter>{__last},
> + reverse_iterator<_Iter>{__first},
> + __value, __proj).base();
> + if (__found == __first)
> + return {__last, __last};
> + else
> + return {ranges::prev(__found), __last};
> + }
> + else
> + {
> + _Iter __found = ranges::find(__first, __last, __value, __proj);
std::move(__proj) here too, for consistency.
> + if (__found == __last)
> + return {__found, __found};
> + for (;;)
> + {
> + __first = ranges::find(ranges::next(__first), __last,
> __value, __proj);
And here.
> + if (__first == __last)
> + return {__found, __first};
> + __found = __first;
> + }
> + }
> + }
> +
> + template<forward_range _Range, typename T, typename _Proj = identity>
> + requires indirect_binary_predicate<ranges::equal_to,
> projected<iterator_t<_Range>, _Proj>, const T*>
> + constexpr borrowed_subrange_t<_Range>
> + operator()(_Range&& __r, const T& __value, _Proj __proj = {}) const
> + { return (*this)(ranges::begin(__r), ranges::end(__r), __value,
> std::move(__proj)); }
> + };
> +
> + inline constexpr __find_last_fn find_last{};
> +
> + struct __find_last_if_fn
> + {
> + template<forward_iterator _Iter, sentinel_for<_Iter> _Sent, typename
> _Proj = identity,
> + indirect_unary_predicate<projected<_Iter, _Proj>> _Pred>
> + constexpr subrange<_Iter>
> + operator()(_Iter __first, _Sent __last, _Pred __pred, _Proj __proj =
> {}) const
> + {
> + if constexpr (same_as<_Iter, _Sent> && bidirectional_iterator<_Iter>)
> + {
> + _Iter __found = ranges::find_if(reverse_iterator<_Iter>{__last},
> + reverse_iterator<_Iter>{__first},
> + __pred, __proj).base();
And here, and std::move(__pred) too, I think.
OK for trunk with those changes here (and the later cases).
