v1/__algorithm/ranges_merge.h

0001 //===----------------------------------------------------------------------===//
0002 //
0003 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
0004 // See https://llvm.org/LICENSE.txt for license information.
0005 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
0006 //
0007 //===----------------------------------------------------------------------===//
0008
0009 #ifndef _LIBCPP___ALGORITHM_RANGES_MERGE_H
0010 #define _LIBCPP___ALGORITHM_RANGES_MERGE_H
0011
0012 #include <__algorithm/in_in_out_result.h>
0013 #include <__algorithm/ranges_copy.h>
0014 #include <__config>
0015 #include <__functional/identity.h>
0016 #include <__functional/invoke.h>
0017 #include <__functional/ranges_operations.h>
0018 #include <__iterator/concepts.h>
0019 #include <__iterator/mergeable.h>
0020 #include <__ranges/access.h>
0021 #include <__ranges/concepts.h>
0022 #include <__ranges/dangling.h>
0023 #include <__type_traits/remove_cvref.h>
0024 #include <__utility/move.h>
0025
0026 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
0027 #  pragma GCC system_header
0028 #endif
0029
0030 _LIBCPP_PUSH_MACROS
0031 #include <__undef_macros>
0032
0033 #if _LIBCPP_STD_VER >= 20
0034
0035 _LIBCPP_BEGIN_NAMESPACE_STD
0036
0037 namespace ranges {
0038
0039 template <class _InIter1, class _InIter2, class _OutIter>
0040 using merge_result = in_in_out_result<_InIter1, _InIter2, _OutIter>;
0041
0042 struct __merge {
0043   template <input_iterator _InIter1,
0044             sentinel_for<_InIter1> _Sent1,
0045             input_iterator _InIter2,
0046             sentinel_for<_InIter2> _Sent2,
0047             weakly_incrementable _OutIter,
0048             class _Comp  = less,
0049             class _Proj1 = identity,
0050             class _Proj2 = identity>
0051     requires mergeable<_InIter1, _InIter2, _OutIter, _Comp, _Proj1, _Proj2>
0052   _LIBCPP_HIDE_FROM_ABI constexpr merge_result<_InIter1, _InIter2, _OutIter> operator()(
0053       _InIter1 __first1,
0054       _Sent1 __last1,
0055       _InIter2 __first2,
0056       _Sent2 __last2,
0057       _OutIter __result,
0058       _Comp __comp   = {},
0059       _Proj1 __proj1 = {},
0060       _Proj2 __proj2 = {}) const {
0061     return __merge::__merge_impl(__first1, __last1, __first2, __last2, __result, __comp, __proj1, __proj2);
0062   }
0063
0064   template <input_range _Range1,
0065             input_range _Range2,
0066             weakly_incrementable _OutIter,
0067             class _Comp  = less,
0068             class _Proj1 = identity,
0069             class _Proj2 = identity>
0070     requires mergeable<iterator_t<_Range1>, iterator_t<_Range2>, _OutIter, _Comp, _Proj1, _Proj2>
0071   _LIBCPP_HIDE_FROM_ABI constexpr merge_result<borrowed_iterator_t<_Range1>, borrowed_iterator_t<_Range2>, _OutIter>
0072   operator()(_Range1&& __range1,
0073              _Range2&& __range2,
0074              _OutIter __result,
0075              _Comp __comp   = {},
0076              _Proj1 __proj1 = {},
0077              _Proj2 __proj2 = {}) const {
0078     return __merge::__merge_impl(
0079         ranges::begin(__range1),
0080         ranges::end(__range1),
0081         ranges::begin(__range2),
0082         ranges::end(__range2),
0083         __result,
0084         __comp,
0085         __proj1,
0086         __proj2);
0087   }
0088
0089   template < class _InIter1,
0090              class _Sent1,
0091              class _InIter2,
0092              class _Sent2,
0093              class _OutIter,
0094              class _Comp,
0095              class _Proj1,
0096              class _Proj2>
0097   _LIBCPP_HIDE_FROM_ABI static constexpr merge_result<__remove_cvref_t<_InIter1>,
0098                                                       __remove_cvref_t<_InIter2>,
0099                                                       __remove_cvref_t<_OutIter>>
0100   __merge_impl(_InIter1&& __first1,
0101                _Sent1&& __last1,
0102                _InIter2&& __first2,
0103                _Sent2&& __last2,
0104                _OutIter&& __result,
0105                _Comp&& __comp,
0106                _Proj1&& __proj1,
0107                _Proj2&& __proj2) {
0108     for (; __first1 != __last1 && __first2 != __last2; ++__result) {
0109       if (std::invoke(__comp, std::invoke(__proj2, *__first2), std::invoke(__proj1, *__first1))) {
0110         *__result = *__first2;
0111         ++__first2;
0112       } else {
0113         *__result = *__first1;
0114         ++__first1;
0115       }
0116     }
0117     auto __ret1 = ranges::copy(std::move(__first1), std::move(__last1), std::move(__result));
0118     auto __ret2 = ranges::copy(std::move(__first2), std::move(__last2), std::move(__ret1.out));
0119     return {std::move(__ret1.in), std::move(__ret2.in), std::move(__ret2.out)};
0120   }
0121 };
0122
0123 inline namespace __cpo {
0124 inline constexpr auto merge = __merge{};
0125 } // namespace __cpo
0126 } // namespace ranges
0127
0128 _LIBCPP_END_NAMESPACE_STD
0129
0130 #endif // _LIBCPP_STD_VER >= 20
0131
0132 _LIBCPP_POP_MACROS
0133
0134 #endif // _LIBCPP___ALGORITHM_RANGES_MERGE_H