libcxx/include/__algorithm/reverse.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_REVERSE_H
  10 #define _LIBCPP___ALGORITHM_REVERSE_H
  11
  12 #include <__algorithm/iter_swap.h>
  13 #include <__algorithm/iterator_operations.h>
  14 #include <__config>
  15 #include <__iterator/iterator_traits.h>
  16 #include <__utility/move.h>
  17
  18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
  19 #  pragma GCC system_header
  20 #endif
  21
  22 _LIBCPP_BEGIN_NAMESPACE_STD
  23
  24 template <class _AlgPolicy, class _BidirectionalIterator>
  25 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
  26 void
  27 __reverse_impl(_BidirectionalIterator __first, _BidirectionalIterator __last, bidirectional_iterator_tag)
  28 {
  29     while (__first != __last)
  30     {
  31         if (__first == --__last)
  32             break;
  33         _IterOps<_AlgPolicy>::iter_swap(__first, __last);
  34         ++__first;
  35     }
  36 }
  37
  38 template <class _AlgPolicy, class _RandomAccessIterator>
  39 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
  40 void
  41 __reverse_impl(_RandomAccessIterator __first, _RandomAccessIterator __last, random_access_iterator_tag)
  42 {
  43     if (__first != __last)
  44         for (; __first < --__last; ++__first)
  45             _IterOps<_AlgPolicy>::iter_swap(__first, __last);
  46 }
  47
  48 template <class _AlgPolicy, class _BidirectionalIterator, class _Sentinel>
  49 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
  50 void __reverse(_BidirectionalIterator __first, _Sentinel __last) {
  51   using _IterCategory = typename _IterOps<_AlgPolicy>::template __iterator_category<_BidirectionalIterator>;
  52   std::__reverse_impl<_AlgPolicy>(std::move(__first), std::move(__last), _IterCategory());
  53 }
  54
  55 template <class _BidirectionalIterator>
  56 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX20
  57 void
  58 reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
  59 {
  60   std::__reverse<_ClassicAlgPolicy>(std::move(__first), std::move(__last));
  61 }
  62
  63 _LIBCPP_END_NAMESPACE_STD
  64
  65 #endif // _LIBCPP___ALGORITHM_REVERSE_H