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 <__config>
13 #include <__algorithm/iter_swap.h>
14 #include <__iterator/iterator_traits.h>
15 
16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17 #pragma GCC system_header
18 #endif
19 
20 _LIBCPP_PUSH_MACROS
21 #include <__undef_macros>
22 
23 _LIBCPP_BEGIN_NAMESPACE_STD
24 
25 template <class _BidirectionalIterator>
26 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
27 void
28 __reverse(_BidirectionalIterator __first, _BidirectionalIterator __last, bidirectional_iterator_tag)
29 {
30     while (__first != __last)
31     {
32         if (__first == --__last)
33             break;
34         _VSTD::iter_swap(__first, __last);
35         ++__first;
36     }
37 }
38 
39 template <class _RandomAccessIterator>
40 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
41 void
42 __reverse(_RandomAccessIterator __first, _RandomAccessIterator __last, random_access_iterator_tag)
43 {
44     if (__first != __last)
45         for (; __first < --__last; ++__first)
46             _VSTD::iter_swap(__first, __last);
47 }
48 
49 template <class _BidirectionalIterator>
50 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
51 void
52 reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
53 {
54     _VSTD::__reverse(__first, __last, typename iterator_traits<_BidirectionalIterator>::iterator_category());
55 }
56 
57 _LIBCPP_END_NAMESPACE_STD
58 
59 _LIBCPP_POP_MACROS
60 
61 #endif // _LIBCPP___ALGORITHM_REVERSE_H
62