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 <__config>
14 #include <__iterator/iterator_traits.h>
15 
16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17 #  pragma GCC system_header
18 #  pragma clang include_instead(<algorithm>)
19 #endif
20 
21 _LIBCPP_BEGIN_NAMESPACE_STD
22 
23 template <class _BidirectionalIterator>
24 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
25 void
26 __reverse(_BidirectionalIterator __first, _BidirectionalIterator __last, bidirectional_iterator_tag)
27 {
28     while (__first != __last)
29     {
30         if (__first == --__last)
31             break;
32         _VSTD::iter_swap(__first, __last);
33         ++__first;
34     }
35 }
36 
37 template <class _RandomAccessIterator>
38 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
39 void
40 __reverse(_RandomAccessIterator __first, _RandomAccessIterator __last, random_access_iterator_tag)
41 {
42     if (__first != __last)
43         for (; __first < --__last; ++__first)
44             _VSTD::iter_swap(__first, __last);
45 }
46 
47 template <class _BidirectionalIterator>
48 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
49 void
50 reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
51 {
52     _VSTD::__reverse(__first, __last, typename iterator_traits<_BidirectionalIterator>::iterator_category());
53 }
54 
55 _LIBCPP_END_NAMESPACE_STD
56 
57 #endif // _LIBCPP___ALGORITHM_REVERSE_H
58