On Thu, 17 Jun 2021 at 16:51, Patrick Palka via Libstdc++
<libstd...@gcc.gnu.org> wrote:
>
> This implements the part of P2210R2 "Superior String Splitting" that
> resolves LWG 3478 for split_view (now named lazy_split_view).
>
> libstdc++-v3/ChangeLog:
>
> * include/std/ranges (lazy_split_view::_OuterIter::__at_end):
> Check _M_trailing_empty.
> (lazy_split_view::_OuterIter::_M_trailing_empty): Define this
> data member.
> (lazy_split_view::_OuterIter::operator++): Set _M_trailing_empty
> appropriately.
> (lazy_split_view::_OuterIter::operator==): Compare
> _M_trailing_empty.
> * testsuite/std/ranges/adaptors/100479.cc (test03): Expect two
> split parts instead of one.
> * testsuite/std/ranges/adaptors/lazy_split.cc (test11): New test.
OK (for trunk only, I think).
> ---
> libstdc++-v3/include/std/ranges | 21 +++++++++++++++----
> .../testsuite/std/ranges/adaptors/100479.cc | 6 +++---
> .../std/ranges/adaptors/lazy_split.cc | 15 +++++++++++++
> 3 files changed, 35 insertions(+), 7 deletions(-)
>
> diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
> index cc1ef112ff1..78562924bee 100644
> --- a/libstdc++-v3/include/std/ranges
> +++ b/libstdc++-v3/include/std/ranges
> @@ -2879,7 +2879,7 @@ namespace views::__adaptor
>
> constexpr bool
> __at_end() const
> - { return __current() == ranges::end(_M_parent->_M_base); }
> + { return __current() == ranges::end(_M_parent->_M_base) &&
> !_M_trailing_empty; }
>
> // [range.lazy.split.outer] p1
> // Many of the following specifications refer to the notional
> member
> @@ -2909,6 +2909,7 @@ namespace views::__adaptor
> [[no_unique_address]]
> __detail::__maybe_present_t<forward_range<_Vp>,
> iterator_t<_Base>> _M_current;
> + bool _M_trailing_empty = false;
>
> public:
> using iterator_concept = conditional_t<forward_range<_Base>,
> @@ -2977,7 +2978,10 @@ namespace views::__adaptor
> // 3505. lazy_split_view::outer-iterator::operator++ misspecified
> const auto __end = ranges::end(_M_parent->_M_base);
> if (__current() == __end)
> - return *this;
> + {
> + _M_trailing_empty = false;
> + return *this;
> + }
> const auto [__pbegin, __pend] = subrange{_M_parent->_M_pattern};
> if (__pbegin == __pend)
> ++__current();
> @@ -2986,7 +2990,11 @@ namespace views::__adaptor
> __current() = ranges::find(std::move(__current()), __end,
> *__pbegin);
> if (__current() != __end)
> - ++__current();
> + {
> + ++__current();
> + if (__current() == __end)
> + _M_trailing_empty = true;
> + }
> }
> else
> do
> @@ -2996,6 +3004,8 @@ namespace views::__adaptor
> if (__p == __pend)
> {
> __current() = __b;
> + if (__current() == __end)
> + _M_trailing_empty = true;
> break;
> }
> } while (++__current() != __end);
> @@ -3018,7 +3028,10 @@ namespace views::__adaptor
> friend constexpr bool
> operator==(const _OuterIter& __x, const _OuterIter& __y)
> requires forward_range<_Base>
> - { return __x._M_current == __y._M_current; }
> + {
> + return __x._M_current == __y._M_current
> + && __x._M_trailing_empty == __y._M_trailing_empty;
> + }
>
> friend constexpr bool
> operator==(const _OuterIter& __x, default_sentinel_t)
> diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/100479.cc
> b/libstdc++-v3/testsuite/std/ranges/adaptors/100479.cc
> index 9899ff92c0b..b8c1e6f4f57 100644
> --- a/libstdc++-v3/testsuite/std/ranges/adaptors/100479.cc
> +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/100479.cc
> @@ -95,11 +95,11 @@ test03()
> | views::drop_while([](auto) { return false; })
> | views::filter([](auto) { return true; });
> static_assert(ranges::forward_range<decltype(v)>);
> - VERIFY( ranges::next(v.begin()) == v.end() );
> + VERIFY( ranges::distance(v) == 2 );
> auto w = v;
> - VERIFY( ranges::next(w.begin()) == w.end() );
> + VERIFY( ranges::distance(v) == 2 );
> auto z = std::move(w);
> - VERIFY( ranges::next(z.begin()) == z.end() );
> + VERIFY( ranges::distance(v) == 2 );
> return true;
> }
>
> diff --git a/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split.cc
> b/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split.cc
> index 12844525d86..133e9a7025b 100644
> --- a/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split.cc
> +++ b/libstdc++-v3/testsuite/std/ranges/adaptors/lazy_split.cc
> @@ -193,6 +193,20 @@ test10()
> VERIFY( ranges::equal(v, (std::string_view[]){"x", "x"}) );
> }
>
> +void
> +test11()
> +{
> + // LWG 3478
> + static_assert(ranges::distance(views::lazy_split("text"sv, "text"sv)) ==
> 2);
> + static_assert(ranges::distance(views::lazy_split(" text "sv, ' ')) == 3);
> + static_assert(ranges::distance(views::lazy_split(" t e x t "sv, ' ')) ==
> 6);
> + static_assert(ranges::distance(views::lazy_split(" text "sv, " "sv)) ==
> 3);
> + static_assert(ranges::distance(views::lazy_split(" text "sv, " "sv))
> == 4);
> + static_assert(ranges::distance(views::lazy_split(" text "sv, " "sv))
> == 4);
> + static_assert(ranges::distance(views::lazy_split("t"sv, 't')) == 2);
> + static_assert(ranges::distance(views::lazy_split("text"sv, ""sv)) == 4);
> +}
> +
> int
> main()
> {
> @@ -206,4 +220,5 @@ main()
> test08();
> test09();
> test10();
> + test11();
> }
> --
> 2.32.0.93.g670b81a890
>
