Implement P2210R2 Superior String Splitting (#2042)

Co-authored-by: Adam Bucior <[email protected]>
Co-authored-by: Casey Carter <[email protected]>
Co-authored-by: Stephan T. Lavavej <[email protected]>

Author: 4 people

stl/inc/algorithm

@@ -1962,156 +1962,6 @@ _NODISCARD _CONSTEXPR20 _FwdItHaystack search(
     return _Search(_First, _Last).first;
 }
 
-#ifdef __cpp_lib_concepts
-namespace ranges {
-    // clang-format off
-    template <class _It1, class _It2, class _Se2, class _Pr, class _Pj1, class _Pj2>
-    concept _Equal_rev_pred_can_memcmp = is_same_v<_Pj1, identity> && is_same_v<_Pj2, identity>
-        && sized_sentinel_for<_Se2, _It2> && _Equal_memcmp_is_safe<_It1, _It2, _Pr>;
-
-    template <input_iterator _It1, input_iterator _It2, sentinel_for<_It2> _Se2, class _Pr, class _Pj1, class _Pj2>
-        requires indirectly_comparable<_It1, _It2, _Pr, _Pj1, _Pj2>
-    _NODISCARD constexpr pair<bool, _It1> _Equal_rev_pred(
-        _It1 _First1, _It2 _First2, const _Se2 _Last2, _Pr _Pred, _Pj1 _Proj1, _Pj2 _Proj2) {
-        // Returns {true, _First1 + (_Last2 - _First2)} if [_First1, ...) equals [_First2, _Last2), and {false, {}}
-        // otherwise.
-        constexpr bool _Optimize = _Equal_rev_pred_can_memcmp<_It1, _It2, _Se2, _Pr, _Pj1, _Pj2>;
-        if constexpr (_Optimize) {
-            if (!_STD is_constant_evaluated()) {
-                bool _Ans;
-                if constexpr (same_as<_It2, _Se2>) {
-                    _Ans = _Memcmp_ranges(_First2, _Last2, _First1) == 0;
-                } else {
-                    _Ans = _Memcmp_count(_First1, _First2, static_cast<size_t>(_Last2 - _First2)) == 0;
-                }
-
-                if (_Ans) {
-                    _First1 += (_Last2 - _First2);
-                    return {true, _STD move(_First1)};
-                } else {
-                    return {false, _It1{}};
-                }
-            }
-        }
-
-        for (; _First2 != _Last2; ++_First1, (void) ++_First2) {
-            if (!_STD invoke(_Pred, _STD invoke(_Proj1, *_First1), _STD invoke(_Proj2, *_First2))) {
-                return {false, _It1{}};
-            }
-        }
-
-        return {true, _STD move(_First1)};
-    }
-    // clang-format on
-
-    class _Search_fn : private _Not_quite_object {
-    public:
-        using _Not_quite_object::_Not_quite_object;
-
-        // clang-format off
-        template <forward_iterator _It1, sentinel_for<_It1> _Se1, forward_iterator _It2, sentinel_for<_It2> _Se2,
-            class _Pr = ranges::equal_to, class _Pj1 = identity, class _Pj2 = identity>
-            requires indirectly_comparable<_It1, _It2, _Pr, _Pj1, _Pj2>
-        _NODISCARD constexpr subrange<_It1> operator()(_It1 _First1, _Se1 _Last1, _It2 _First2, _Se2 _Last2,
-            _Pr _Pred = {}, _Pj1 _Proj1 = {}, _Pj2 _Proj2 = {}) const {
-            _Adl_verify_range(_First1, _Last1);
-            _Adl_verify_range(_First2, _Last2);
-            auto _UFirst1 = _Get_unwrapped(_STD move(_First1));
-            auto _ULast1  = _Get_unwrapped(_STD move(_Last1));
-            auto _UFirst2 = _Get_unwrapped(_STD move(_First2));
-            auto _ULast2  = _Get_unwrapped(_STD move(_Last2));
-
-            if constexpr (sized_sentinel_for<_Se1, _It1> && sized_sentinel_for<_Se2, _It2>) {
-                const auto _Count1 = _ULast1 - _UFirst1;
-                const auto _Count2 = _ULast2 - _UFirst2;
-                auto _UResult =
-                    _Search_sized(_STD move(_UFirst1), _STD move(_ULast1), _Count1, _STD move(_UFirst2),
-                        _STD move(_ULast2), _Count2, _Pass_fn(_Pred), _Pass_fn(_Proj1), _Pass_fn(_Proj2));
-                return _Rewrap_subrange<subrange<_It1>>(_First1, _STD move(_UResult));
-            } else {
-                auto _UResult = _Search_unsized(_STD move(_UFirst1), _STD move(_ULast1), _STD move(_UFirst2),
-                    _STD move(_ULast2), _Pass_fn(_Pred), _Pass_fn(_Proj1), _Pass_fn(_Proj2));
-                return _Rewrap_subrange<subrange<_It1>>(_First1, _STD move(_UResult));
-            }
-        }
-
-        template <forward_range _Rng1, forward_range _Rng2, class _Pr = ranges::equal_to, class _Pj1 = identity,
-            class _Pj2 = identity>
-            requires indirectly_comparable<iterator_t<_Rng1>, iterator_t<_Rng2>, _Pr, _Pj1, _Pj2>
-        _NODISCARD constexpr borrowed_subrange_t<_Rng1> operator()(
-            _Rng1&& _Range1, _Rng2&& _Range2, _Pr _Pred = {}, _Pj1 _Proj1 = {}, _Pj2 _Proj2 = {}) const {
-            if constexpr (sized_range<_Rng1> && sized_range<_Rng2>) {
-                const auto _Count1 = _RANGES distance(_Range1);
-                const auto _Count2 = _RANGES distance(_Range2);
-                auto _UResult = _Search_sized(_Ubegin(_Range1), _Uend(_Range1), _Count1,
-                    _Ubegin(_Range2), _Uend(_Range2), _Count2,
-                    _Pass_fn(_Pred), _Pass_fn(_Proj1), _Pass_fn(_Proj2));
-                return _Rewrap_subrange<borrowed_subrange_t<_Rng1>>(_Range1, _STD move(_UResult));
-            } else {
-                auto _UResult = _Search_unsized(_Ubegin(_Range1), _Uend(_Range1),
-                    _Ubegin(_Range2), _Uend(_Range2),
-                    _Pass_fn(_Pred), _Pass_fn(_Proj1), _Pass_fn(_Proj2));
-                return _Rewrap_subrange<borrowed_subrange_t<_Rng1>>(_Range1, _STD move(_UResult));
-            }
-        }
-        // clang-format on
-
-    private:
-        template <class _It1, class _Se1, class _It2, class _Se2, class _Pr, class _Pj1, class _Pj2>
-        _NODISCARD static constexpr subrange<_It1> _Search_sized(_It1 _First1, const _Se1 _Last1,
-            iter_difference_t<_It1> _Count1, _It2 _First2, const _Se2 _Last2, const iter_difference_t<_It2> _Count2,
-            _Pr _Pred, _Pj1 _Proj1, _Pj2 _Proj2) {
-            _STL_INTERNAL_STATIC_ASSERT(forward_iterator<_It1>);
-            _STL_INTERNAL_STATIC_ASSERT(sentinel_for<_Se1, _It1>);
-            _STL_INTERNAL_STATIC_ASSERT(forward_iterator<_It2>);
-            _STL_INTERNAL_STATIC_ASSERT(sentinel_for<_Se2, _It2>);
-            _STL_INTERNAL_STATIC_ASSERT(indirectly_comparable<_It1, _It2, _Pr, _Pj1, _Pj2>);
-            _STL_INTERNAL_CHECK(_RANGES distance(_First1, _Last1) == _Count1);
-            _STL_INTERNAL_CHECK(_RANGES distance(_First2, _Last2) == _Count2);
-
-            for (; _Count1 >= _Count2; ++_First1, (void) --_Count1) {
-                auto [_Match, _Mid1] = _RANGES _Equal_rev_pred(_First1, _First2, _Last2, _Pred, _Proj1, _Proj2);
-                if (_Match) {
-                    return {_STD move(_First1), _STD move(_Mid1)};
-                }
-            }
-
-            _First1 = _Find_last_iterator(_First1, _Last1, _Count1);
-            return {_First1, _First1};
-        }
-
-        template <class _It1, class _Se1, class _It2, class _Se2, class _Pr, class _Pj1, class _Pj2>
-        _NODISCARD static constexpr subrange<_It1> _Search_unsized(
-            _It1 _First1, const _Se1 _Last1, _It2 _First2, const _Se2 _Last2, _Pr _Pred, _Pj1 _Proj1, _Pj2 _Proj2) {
-            _STL_INTERNAL_STATIC_ASSERT(forward_iterator<_It1>);
-            _STL_INTERNAL_STATIC_ASSERT(sentinel_for<_Se1, _It1>);
-            _STL_INTERNAL_STATIC_ASSERT(forward_iterator<_It2>);
-            _STL_INTERNAL_STATIC_ASSERT(sentinel_for<_Se2, _It2>);
-            _STL_INTERNAL_STATIC_ASSERT(indirectly_comparable<_It1, _It2, _Pr, _Pj1, _Pj2>);
-
-            for (;; ++_First1) {
-                auto _Mid1 = _First1;
-                for (auto _Mid2 = _First2;; ++_Mid1, (void) ++_Mid2) {
-                    if (_Mid2 == _Last2) { // match
-                        return {_STD move(_First1), _STD move(_Mid1)};
-                    }
-
-                    if (_Mid1 == _Last1) { // not enough haystack left to find a match
-                        return {_Mid1, _Mid1};
-                    }
-
-                    if (!_STD invoke(_Pred, _STD invoke(_Proj1, *_Mid1), _STD invoke(_Proj2, *_Mid2))) { // mismatch
-                        break;
-                    }
-                }
-            }
-        }
-    };
-
-    inline constexpr _Search_fn search{_Not_quite_object::_Construct_tag{}};
-} // namespace ranges
-#endif // __cpp_lib_concepts
-
 template <class _FwdIt, class _Diff, class _Ty, class _Pr>
 _NODISCARD _CONSTEXPR20 _FwdIt search_n(
     const _FwdIt _First, _FwdIt _Last, const _Diff _Count_raw, const _Ty& _Val, _Pr _Pred) {