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_MOVE_BACKWARD_H
10 #define _LIBCPP___ALGORITHM_MOVE_BACKWARD_H
11
12 #include <__config>
13 #include <__algorithm/unwrap_iter.h>
14 #include <cstring>
15 #include <utility>
16 #include <type_traits>
17
18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19 #pragma GCC system_header
20 #endif
21
22 _LIBCPP_PUSH_MACROS
23 #include <__undef_macros>
24
25 _LIBCPP_BEGIN_NAMESPACE_STD
26
27 template <class _InputIterator, class _OutputIterator>
28 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
29 _OutputIterator
__move_backward_constexpr(_InputIterator __first,_InputIterator __last,_OutputIterator __result)30 __move_backward_constexpr(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
31 {
32 while (__first != __last)
33 *--__result = _VSTD::move(*--__last);
34 return __result;
35 }
36
37 template <class _InputIterator, class _OutputIterator>
38 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
39 _OutputIterator
__move_backward(_InputIterator __first,_InputIterator __last,_OutputIterator __result)40 __move_backward(_InputIterator __first, _InputIterator __last, _OutputIterator __result)
41 {
42 return _VSTD::__move_backward_constexpr(__first, __last, __result);
43 }
44
45 template <class _Tp, class _Up>
46 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14
47 typename enable_if
48 <
49 is_same<typename remove_const<_Tp>::type, _Up>::value &&
50 is_trivially_move_assignable<_Up>::value,
51 _Up*
52 >::type
__move_backward(_Tp * __first,_Tp * __last,_Up * __result)53 __move_backward(_Tp* __first, _Tp* __last, _Up* __result)
54 {
55 const size_t __n = static_cast<size_t>(__last - __first);
56 if (__n > 0)
57 {
58 __result -= __n;
59 _VSTD::memmove(__result, __first, __n * sizeof(_Up));
60 }
61 return __result;
62 }
63
64 template <class _BidirectionalIterator1, class _BidirectionalIterator2>
65 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17
66 _BidirectionalIterator2
move_backward(_BidirectionalIterator1 __first,_BidirectionalIterator1 __last,_BidirectionalIterator2 __result)67 move_backward(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
68 _BidirectionalIterator2 __result)
69 {
70 if (__libcpp_is_constant_evaluated()) {
71 return _VSTD::__move_backward_constexpr(__first, __last, __result);
72 } else {
73 return _VSTD::__rewrap_iter(__result,
74 _VSTD::__move_backward(_VSTD::__unwrap_iter(__first),
75 _VSTD::__unwrap_iter(__last),
76 _VSTD::__unwrap_iter(__result)));
77 }
78 }
79
80 _LIBCPP_END_NAMESPACE_STD
81
82 _LIBCPP_POP_MACROS
83
84 #endif // _LIBCPP___ALGORITHM_MOVE_BACKWARD_H
85