__cxx03/__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___CXX03___ALGORITHM_RANGES_MERGE_H
0010 #define _LIBCPP___CXX03___ALGORITHM_RANGES_MERGE_H
0011
0012 #include <__cxx03/__algorithm/in_in_out_result.h>
0013 #include <__cxx03/__algorithm/ranges_copy.h>
0014 #include <__cxx03/__config>
0015 #include <__cxx03/__functional/identity.h>
0016 #include <__cxx03/__functional/invoke.h>
0017 #include <__cxx03/__functional/ranges_operations.h>
0018 #include <__cxx03/__iterator/concepts.h>
0019 #include <__cxx03/__iterator/mergeable.h>
0020 #include <__cxx03/__ranges/access.h>
0021 #include <__cxx03/__ranges/concepts.h>
0022 #include <__cxx03/__ranges/dangling.h>
0023 #include <__cxx03/__type_traits/remove_cvref.h>
0024 #include <__cxx03/__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 <__cxx03/__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 namespace __merge {
0043
0044 template < class _InIter1,
0045            class _Sent1,
0046            class _InIter2,
0047            class _Sent2,
0048            class _OutIter,
0049            class _Comp,
0050            class _Proj1,
0051            class _Proj2>
0052 _LIBCPP_HIDE_FROM_ABI constexpr merge_result<__remove_cvref_t<_InIter1>,
0053                                              __remove_cvref_t<_InIter2>,
0054                                              __remove_cvref_t<_OutIter>>
0055 __merge_impl(_InIter1&& __first1,
0056              _Sent1&& __last1,
0057              _InIter2&& __first2,
0058              _Sent2&& __last2,
0059              _OutIter&& __result,
0060              _Comp&& __comp,
0061              _Proj1&& __proj1,
0062              _Proj2&& __proj2) {
0063   for (; __first1 != __last1 && __first2 != __last2; ++__result) {
0064     if (std::invoke(__comp, std::invoke(__proj2, *__first2), std::invoke(__proj1, *__first1))) {
0065       *__result = *__first2;
0066       ++__first2;
0067     } else {
0068       *__result = *__first1;
0069       ++__first1;
0070     }
0071   }
0072   auto __ret1 = ranges::copy(std::move(__first1), std::move(__last1), std::move(__result));
0073   auto __ret2 = ranges::copy(std::move(__first2), std::move(__last2), std::move(__ret1.out));
0074   return {std::move(__ret1.in), std::move(__ret2.in), std::move(__ret2.out)};
0075 }
0076
0077 struct __fn {
0078   template <input_iterator _InIter1,
0079             sentinel_for<_InIter1> _Sent1,
0080             input_iterator _InIter2,
0081             sentinel_for<_InIter2> _Sent2,
0082             weakly_incrementable _OutIter,
0083             class _Comp  = less,
0084             class _Proj1 = identity,
0085             class _Proj2 = identity>
0086     requires mergeable<_InIter1, _InIter2, _OutIter, _Comp, _Proj1, _Proj2>
0087   _LIBCPP_HIDE_FROM_ABI constexpr merge_result<_InIter1, _InIter2, _OutIter> operator()(
0088       _InIter1 __first1,
0089       _Sent1 __last1,
0090       _InIter2 __first2,
0091       _Sent2 __last2,
0092       _OutIter __result,
0093       _Comp __comp   = {},
0094       _Proj1 __proj1 = {},
0095       _Proj2 __proj2 = {}) const {
0096     return __merge::__merge_impl(__first1, __last1, __first2, __last2, __result, __comp, __proj1, __proj2);
0097   }
0098
0099   template <input_range _Range1,
0100             input_range _Range2,
0101             weakly_incrementable _OutIter,
0102             class _Comp  = less,
0103             class _Proj1 = identity,
0104             class _Proj2 = identity>
0105     requires mergeable<iterator_t<_Range1>, iterator_t<_Range2>, _OutIter, _Comp, _Proj1, _Proj2>
0106   _LIBCPP_HIDE_FROM_ABI constexpr merge_result<borrowed_iterator_t<_Range1>, borrowed_iterator_t<_Range2>, _OutIter>
0107   operator()(_Range1&& __range1,
0108              _Range2&& __range2,
0109              _OutIter __result,
0110              _Comp __comp   = {},
0111              _Proj1 __proj1 = {},
0112              _Proj2 __proj2 = {}) const {
0113     return __merge::__merge_impl(
0114         ranges::begin(__range1),
0115         ranges::end(__range1),
0116         ranges::begin(__range2),
0117         ranges::end(__range2),
0118         __result,
0119         __comp,
0120         __proj1,
0121         __proj2);
0122   }
0123 };
0124
0125 } // namespace __merge
0126
0127 inline namespace __cpo {
0128 inline constexpr auto merge = __merge::__fn{};
0129 } // namespace __cpo
0130 } // namespace ranges
0131
0132 _LIBCPP_END_NAMESPACE_STD
0133
0134 #endif // _LIBCPP_STD_VER >= 20
0135
0136 _LIBCPP_POP_MACROS
0137
0138 #endif // _LIBCPP___CXX03___ALGORITHM_RANGES_MERGE_H