libcxx/include/__cxx03/__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 <__cxx03/__algorithm/in_in_out_result.h>
  13 #include <__cxx03/__algorithm/ranges_copy.h>
  14 #include <__cxx03/__config>
  15 #include <__cxx03/__functional/identity.h>
  16 #include <__cxx03/__functional/invoke.h>
  17 #include <__cxx03/__functional/ranges_operations.h>
  18 #include <__cxx03/__iterator/concepts.h>
  19 #include <__cxx03/__iterator/mergeable.h>
  20 #include <__cxx03/__ranges/access.h>
  21 #include <__cxx03/__ranges/concepts.h>
  22 #include <__cxx03/__ranges/dangling.h>
  23 #include <__cxx03/__type_traits/remove_cvref.h>
  24 #include <__cxx03/__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 <__cxx03/__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 namespace __merge {
  43
  44 template < class _InIter1,
  45            class _Sent1,
  46            class _InIter2,
  47            class _Sent2,
  48            class _OutIter,
  49            class _Comp,
  50            class _Proj1,
  51            class _Proj2>
  52 _LIBCPP_HIDE_FROM_ABI constexpr merge_result<__remove_cvref_t<_InIter1>,
  53                                              __remove_cvref_t<_InIter2>,
  54                                              __remove_cvref_t<_OutIter>>
  55 __merge_impl(_InIter1&& __first1,
  56              _Sent1&& __last1,
  57              _InIter2&& __first2,
  58              _Sent2&& __last2,
  59              _OutIter&& __result,
  60              _Comp&& __comp,
  61              _Proj1&& __proj1,
  62              _Proj2&& __proj2) {
  63   for (; __first1 != __last1 && __first2 != __last2; ++__result) {
  64     if (std::invoke(__comp, std::invoke(__proj2, *__first2), std::invoke(__proj1, *__first1))) {
  65       *__result = *__first2;
  66       ++__first2;
  67     } else {
  68       *__result = *__first1;
  69       ++__first1;
  70     }
  71   }
  72   auto __ret1 = ranges::copy(std::move(__first1), std::move(__last1), std::move(__result));
  73   auto __ret2 = ranges::copy(std::move(__first2), std::move(__last2), std::move(__ret1.out));
  74   return {std::move(__ret1.in), std::move(__ret2.in), std::move(__ret2.out)};
  75 }
  76
  77 struct __fn {
  78   template <input_iterator _InIter1,
  79             sentinel_for<_InIter1> _Sent1,
  80             input_iterator _InIter2,
  81             sentinel_for<_InIter2> _Sent2,
  82             weakly_incrementable _OutIter,
  83             class _Comp  = less,
  84             class _Proj1 = identity,
  85             class _Proj2 = identity>
  86     requires mergeable<_InIter1, _InIter2, _OutIter, _Comp, _Proj1, _Proj2>
  87   _LIBCPP_HIDE_FROM_ABI constexpr merge_result<_InIter1, _InIter2, _OutIter> operator()(
  88       _InIter1 __first1,
  89       _Sent1 __last1,
  90       _InIter2 __first2,
  91       _Sent2 __last2,
  92       _OutIter __result,
  93       _Comp __comp   = {},
  94       _Proj1 __proj1 = {},
  95       _Proj2 __proj2 = {}) const {
  96     return __merge::__merge_impl(__first1, __last1, __first2, __last2, __result, __comp, __proj1, __proj2);
  97   }
  98
  99   template <input_range _Range1,
 100             input_range _Range2,
 101             weakly_incrementable _OutIter,
 102             class _Comp  = less,
 103             class _Proj1 = identity,
 104             class _Proj2 = identity>
 105     requires mergeable<iterator_t<_Range1>, iterator_t<_Range2>, _OutIter, _Comp, _Proj1, _Proj2>
 106   _LIBCPP_HIDE_FROM_ABI constexpr merge_result<borrowed_iterator_t<_Range1>, borrowed_iterator_t<_Range2>, _OutIter>
 107   operator()(_Range1&& __range1,
 108              _Range2&& __range2,
 109              _OutIter __result,
 110              _Comp __comp   = {},
 111              _Proj1 __proj1 = {},
 112              _Proj2 __proj2 = {}) const {
 113     return __merge::__merge_impl(
 114         ranges::begin(__range1),
 115         ranges::end(__range1),
 116         ranges::begin(__range2),
 117         ranges::end(__range2),
 118         __result,
 119         __comp,
 120         __proj1,
 121         __proj2);
 122   }
 123 };
 124
 125 } // namespace __merge
 126
 127 inline namespace __cpo {
 128 inline constexpr auto merge = __merge::__fn{};
 129 } // namespace __cpo
 130 } // namespace ranges
 131
 132 _LIBCPP_END_NAMESPACE_STD
 133
 134 #endif // _LIBCPP_STD_VER >= 20
 135
 136 _LIBCPP_POP_MACROS
 137
 138 #endif // _LIBCPP___ALGORITHM_RANGES_MERGE_H