libcxx/include/__cxx03/__algorithm/ranges_copy_n.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_COPY_N_H
  10 #define _LIBCPP___ALGORITHM_RANGES_COPY_N_H
  11
  12 #include <__cxx03/__algorithm/copy.h>
  13 #include <__cxx03/__algorithm/in_out_result.h>
  14 #include <__cxx03/__algorithm/iterator_operations.h>
  15 #include <__cxx03/__algorithm/ranges_copy.h>
  16 #include <__cxx03/__config>
  17 #include <__cxx03/__functional/identity.h>
  18 #include <__cxx03/__iterator/concepts.h>
  19 #include <__cxx03/__iterator/incrementable_traits.h>
  20 #include <__cxx03/__iterator/unreachable_sentinel.h>
  21 #include <__cxx03/__iterator/wrap_iter.h>
  22 #include <__cxx03/__utility/move.h>
  23
  24 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  25 #  pragma GCC system_header
  26 #endif
  27
  28 _LIBCPP_PUSH_MACROS
  29 #include <__cxx03/__undef_macros>
  30
  31 _LIBCPP_BEGIN_NAMESPACE_STD
  32
  33 #if _LIBCPP_STD_VER >= 20
  34
  35 namespace ranges {
  36
  37 template <class _Ip, class _Op>
  38 using copy_n_result = in_out_result<_Ip, _Op>;
  39
  40 namespace __copy_n {
  41 struct __fn {
  42   template <class _InIter, class _DiffType, class _OutIter>
  43   _LIBCPP_HIDE_FROM_ABI constexpr static copy_n_result<_InIter, _OutIter>
  44   __go(_InIter __first, _DiffType __n, _OutIter __result) {
  45     while (__n != 0) {
  46       *__result = *__first;
  47       ++__first;
  48       ++__result;
  49       --__n;
  50     }
  51     return {std::move(__first), std::move(__result)};
  52   }
  53
  54   template <random_access_iterator _InIter, class _DiffType, random_access_iterator _OutIter>
  55   _LIBCPP_HIDE_FROM_ABI constexpr static copy_n_result<_InIter, _OutIter>
  56   __go(_InIter __first, _DiffType __n, _OutIter __result) {
  57     auto __ret = std::__copy<_RangeAlgPolicy>(__first, __first + __n, __result);
  58     return {__ret.first, __ret.second};
  59   }
  60
  61   template <input_iterator _Ip, weakly_incrementable _Op>
  62     requires indirectly_copyable<_Ip, _Op>
  63   _LIBCPP_HIDE_FROM_ABI constexpr copy_n_result<_Ip, _Op>
  64   operator()(_Ip __first, iter_difference_t<_Ip> __n, _Op __result) const {
  65     return __go(std::move(__first), __n, std::move(__result));
  66   }
  67 };
  68 } // namespace __copy_n
  69
  70 inline namespace __cpo {
  71 inline constexpr auto copy_n = __copy_n::__fn{};
  72 } // namespace __cpo
  73 } // namespace ranges
  74
  75 #endif // _LIBCPP_STD_VER >= 20
  76
  77 _LIBCPP_END_NAMESPACE_STD
  78
  79 _LIBCPP_POP_MACROS
  80
  81 #endif // _LIBCPP___ALGORITHM_RANGES_COPY_N_H