Re: [PATCH 1/3] libstdc++: Implement ranges::contains/contains_subrange from P2302R4

[Jonathan Wakely <jwakely@redhat.com>]

On Mon, 14 Nov 2022 at 04:51, Patrick Palka via Libstdc++
<libstdc++@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 (__contains_fn, contains): Define.
>         (__contains_subrange_fn, contains_subrange): Define.
>         * testsuite/25_algorithms/contains/1.cc: New test.
>         * testsuite/25_algorithms/contains_subrange/1.cc: New test.
> ---
>  libstdc++-v3/include/bits/ranges_algo.h       | 54 +++++++++++++++++++
>  .../testsuite/25_algorithms/contains/1.cc     | 33 ++++++++++++
>  .../25_algorithms/contains_subrange/1.cc      | 35 ++++++++++++
>  3 files changed, 122 insertions(+)
>  create mode 100644 libstdc++-v3/testsuite/25_algorithms/contains/1.cc
>  create mode 100644 libstdc++-v3/testsuite/25_algorithms/contains_subrange/1.cc
>
> diff --git a/libstdc++-v3/include/bits/ranges_algo.h b/libstdc++-v3/include/bits/ranges_algo.h
> index de71bd07a2f..da0ca981dc3 100644
> --- a/libstdc++-v3/include/bits/ranges_algo.h
> +++ b/libstdc++-v3/include/bits/ranges_algo.h
> @@ -3464,6 +3464,60 @@ namespace ranges
>
>    inline constexpr __prev_permutation_fn prev_permutation{};
>
> +#if __cplusplus > 202002L
> +  struct __contains_fn
> +  {
> +    template<input_iterator _Iter, sentinel_for<_Iter> _Sent,
> +           typename _Tp, typename _Proj = identity>
> +      requires indirect_binary_predicate<ranges::equal_to,
> +                                        projected<_Iter, _Proj>, const _Tp*>
> +      constexpr bool
> +      operator()(_Iter __first, _Sent __last, const _Tp& __value, _Proj __proj = {}) const
> +      { return ranges::find(std::move(__first), __last, __value, __proj) != __last; }

Should this use std::move(__proj)?



> +
> +    template<input_range _Range, typename _Tp, typename _Proj = identity>
> +      requires indirect_binary_predicate<ranges::equal_to,
> +                                        projected<iterator_t<_Range>, _Proj>, const _Tp*>
> +      constexpr bool
> +      operator()(_Range&& __r, const _Tp& __value, _Proj __proj = {}) const
> +      { return (*this)(ranges::begin(__r), ranges::end(__r), __value, std::move(__proj)); }
> +  };
> +
> +  inline constexpr __contains_fn contains{};
> +
> +  struct __contains_subrange_fn
> +  {
> +    template<forward_iterator _Iter1, sentinel_for<_Iter1> _Sent1,
> +            forward_iterator _Iter2, sentinel_for<_Iter2> _Sent2,
> +            typename _Pred = ranges::equal_to,
> +            typename Proj1 = identity, typename Proj2 = identity>
> +      requires indirectly_comparable<_Iter1, _Iter2, _Pred, Proj1, Proj2>
> +      constexpr bool
> +      operator()(_Iter1 __first1, _Sent1 __last1, _Iter2 __first2, _Sent2 __last2,
> +                _Pred __pred = {}, Proj1 __proj1 = {}, Proj2 __proj2 = {}) const
> +      {
> +       return __first2 == __last2
> +         || !ranges::search(__first1, __last1, __first2, __last2,
> +                            std::move(__pred), std::move(__proj1), std::move(__proj2)).empty();
> +      }
> +
> +    template<forward_range _Range1, forward_range _Range2,
> +            typename _Pred = ranges::equal_to,
> +            typename _Proj1 = identity, typename _Proj2 = identity>
> +      requires indirectly_comparable<iterator_t<_Range1>, iterator_t<_Range2>,
> +                                    _Pred, _Proj1, _Proj2>
> +      constexpr bool
> +      operator()(_Range1&& __r1, _Range2&& __r2, _Pred __pred = {},
> +                _Proj1 __proj1 = {}, _Proj2 __proj2 = {}) const
> +      {
> +       return (*this)(ranges::begin(__r1), ranges::end(__r1),
> +                      ranges::begin(__r2), ranges::end(__r2),
> +                      std::move(__pred), std::move(__proj1), std::move(__proj2));
> +      }
> +  };
> +
> +  inline constexpr __contains_subrange_fn contains_subrange{};
> +#endif // C++23
>  } // namespace ranges
>
>  #define __cpp_lib_shift 201806L
> diff --git a/libstdc++-v3/testsuite/25_algorithms/contains/1.cc b/libstdc++-v3/testsuite/25_algorithms/contains/1.cc
> new file mode 100644
> index 00000000000..146ab593b70
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/25_algorithms/contains/1.cc
> @@ -0,0 +1,33 @@
> +// { dg-options "-std=gnu++23" }
> +// { dg-do run { target c++23 } }
> +
> +#include <algorithm>
> +#include <testsuite_hooks.h>
> +#include <testsuite_iterators.h>
> +
> +namespace ranges = std::ranges;
> +
> +void
> +test01()
> +{
> +  int x[] = {1,2,3};
> +  using to_input = __gnu_test::test_input_range<int>;
> +  VERIFY( ranges::contains(to_input(x), 1) );
> +  VERIFY( ranges::contains(to_input(x), 2) );
> +  VERIFY( ranges::contains(to_input(x), 3) );
> +  VERIFY( !ranges::contains(to_input(x), 4) );
> +  VERIFY( !ranges::contains(x, x+2, 3) );
> +  auto neg = [](int n) { return -n; };
> +  VERIFY( ranges::contains(to_input(x), -1, neg) );
> +  VERIFY( ranges::contains(to_input(x), -2, neg) );
> +  VERIFY( ranges::contains(to_input(x), -3, neg) );
> +  VERIFY( !ranges::contains(to_input(x), -4, neg) );
> +
> +  VERIFY( !ranges::contains(x, x+2, -3, neg) );
> +}
> +
> +int
> +main()
> +{
> +  test01();
> +}
> diff --git a/libstdc++-v3/testsuite/25_algorithms/contains_subrange/1.cc b/libstdc++-v3/testsuite/25_algorithms/contains_subrange/1.cc
> new file mode 100644
> index 00000000000..62b92795f94
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/25_algorithms/contains_subrange/1.cc
> @@ -0,0 +1,35 @@
> +// { dg-options "-std=gnu++23" }
> +// { dg-do run { target c++23 } }
> +
> +#include <algorithm>
> +#include <testsuite_hooks.h>
> +#include <testsuite_iterators.h>
> +
> +namespace ranges = std::ranges;
> +
> +void
> +test01()
> +{
> +  int x[] = {1,2,3,4,5};
> +  int y[] = {2,3,4};
> +  int z[] = {4,5,6};
> +  __gnu_test::test_forward_range<int> rx(x);
> +  __gnu_test::test_forward_range<int> ry(y);
> +  __gnu_test::test_forward_range<int> rz(z);
> +  VERIFY( ranges::contains_subrange(rx, ry) );
> +  VERIFY( !ranges::contains_subrange(rx, rz) );
> +  VERIFY( ranges::contains_subrange(rx, ry, ranges::less{}) );
> +  VERIFY( ranges::contains_subrange(rx, rz, ranges::less{}) );
> +  auto plus3 = [](int n) { return n+3; };
> +  VERIFY( !ranges::contains_subrange(rx, ry, ranges::equal_to{}, plus3) );
> +  VERIFY( ranges::contains_subrange(rx, rz, ranges::equal_to{}, plus3) );
> +
> +  VERIFY( ranges::contains_subrange(x, x+2, y, y+1) );
> +  VERIFY( !ranges::contains_subrange(x, x+2, y, y+2) );
> +}
> +
> +int
> +main()
> +{
> +  test01();
> +}
> --
> 2.38.1.420.g319605f8f0
>