libcxx/include/__algorithm/ranges_merge.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef _LIBCPP___ALGORITHM_RANGES_MERGE_H
  10 #define _LIBCPP___ALGORITHM_RANGES_MERGE_H
  11
  12 #include <__algorithm/in_in_out_result.h>
  13 #include <__algorithm/ranges_copy.h>
  14 #include <__config>
  15 #include <__functional/identity.h>
  16 #include <__functional/invoke.h>
  17 #include <__functional/ranges_operations.h>
  18 #include <__iterator/concepts.h>
  19 #include <__iterator/mergeable.h>
  20 #include <__ranges/access.h>
  21 #include <__ranges/concepts.h>
  22 #include <__ranges/dangling.h>
  23 #include <__type_traits/remove_cvref.h>
  24 #include <__utility/move.h>
  25
  26 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  27 #  pragma GCC system_header
  28 #endif
  29
  30 _LIBCPP_PUSH_MACROS
  31 #include <__undef_macros>
  32
  33 #if _LIBCPP_STD_VER >= 20
  34
  35 _LIBCPP_BEGIN_NAMESPACE_STD
  36
  37 namespace ranges {
  38
  39 template <class _InIter1, class _InIter2, class _OutIter>
  40 using merge_result = in_in_out_result<_InIter1, _InIter2, _OutIter>;
  41
  42 struct __merge {
  43   template <input_iterator _InIter1,
  44             sentinel_for<_InIter1> _Sent1,
  45             input_iterator _InIter2,
  46             sentinel_for<_InIter2> _Sent2,
  47             weakly_incrementable _OutIter,
  48             class _Comp  = less,
  49             class _Proj1 = identity,
  50             class _Proj2 = identity>
  51     requires mergeable<_InIter1, _InIter2, _OutIter, _Comp, _Proj1, _Proj2>
  52   _LIBCPP_HIDE_FROM_ABI constexpr merge_result<_InIter1, _InIter2, _OutIter> operator()(
  53       _InIter1 __first1,
  54       _Sent1 __last1,
  55       _InIter2 __first2,
  56       _Sent2 __last2,
  57       _OutIter __result,
  58       _Comp __comp   = {},
  59       _Proj1 __proj1 = {},
  60       _Proj2 __proj2 = {}) const {
  61     return __merge::__merge_impl(__first1, __last1, __first2, __last2, __result, __comp, __proj1, __proj2);
  62   }
  63
  64   template <input_range _Range1,
  65             input_range _Range2,
  66             weakly_incrementable _OutIter,
  67             class _Comp  = less,
  68             class _Proj1 = identity,
  69             class _Proj2 = identity>
  70     requires mergeable<iterator_t<_Range1>, iterator_t<_Range2>, _OutIter, _Comp, _Proj1, _Proj2>
  71   _LIBCPP_HIDE_FROM_ABI constexpr merge_result<borrowed_iterator_t<_Range1>, borrowed_iterator_t<_Range2>, _OutIter>
  72   operator()(_Range1&& __range1,
  73              _Range2&& __range2,
  74              _OutIter __result,
  75              _Comp __comp   = {},
  76              _Proj1 __proj1 = {},
  77              _Proj2 __proj2 = {}) const {
  78     return __merge::__merge_impl(
  79         ranges::begin(__range1),
  80         ranges::end(__range1),
  81         ranges::begin(__range2),
  82         ranges::end(__range2),
  83         __result,
  84         __comp,
  85         __proj1,
  86         __proj2);
  87   }
  88
  89   template < class _InIter1,
  90              class _Sent1,
  91              class _InIter2,
  92              class _Sent2,
  93              class _OutIter,
  94              class _Comp,
  95              class _Proj1,
  96              class _Proj2>
  97   _LIBCPP_HIDE_FROM_ABI static constexpr merge_result<__remove_cvref_t<_InIter1>,
  98                                                       __remove_cvref_t<_InIter2>,
  99                                                       __remove_cvref_t<_OutIter>>
 100   __merge_impl(_InIter1&& __first1,
 101                _Sent1&& __last1,
 102                _InIter2&& __first2,
 103                _Sent2&& __last2,
 104                _OutIter&& __result,
 105                _Comp&& __comp,
 106                _Proj1&& __proj1,
 107                _Proj2&& __proj2) {
 108     for (; __first1 != __last1 && __first2 != __last2; ++__result) {
 109       if (std::invoke(__comp, std::invoke(__proj2, *__first2), std::invoke(__proj1, *__first1))) {
 110         *__result = *__first2;
 111         ++__first2;
 112       } else {
 113         *__result = *__first1;
 114         ++__first1;
 115       }
 116     }
 117     auto __ret1 = ranges::copy(std::move(__first1), std::move(__last1), std::move(__result));
 118     auto __ret2 = ranges::copy(std::move(__first2), std::move(__last2), std::move(__ret1.out));
 119     return {std::move(__ret1.in), std::move(__ret2.in), std::move(__ret2.out)};
 120   }
 121 };
 122
 123 inline namespace __cpo {
 124 inline constexpr auto merge = __merge{};
 125 } // namespace __cpo
 126 } // namespace ranges
 127
 128 _LIBCPP_END_NAMESPACE_STD
 129
 130 #endif // _LIBCPP_STD_VER >= 20
 131
 132 _LIBCPP_POP_MACROS
 133
 134 #endif // _LIBCPP___ALGORITHM_RANGES_MERGE_H