mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-24 23:09:02 +00:00
56 lines
1.5 KiB
C
56 lines
1.5 KiB
C
|
//===----------------------------------------------------------------------===//
|
||
|
|
//
|
||
|
|
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
|
||
|
|
// See https://llvm.org/LICENSE.txt for license information.
|
||
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
||
|
|
//
|
||
|
|
//===----------------------------------------------------------------------===//
|
||
|
|
|
||
|
|
#ifndef _LIBCPP___ALGORITHM_SHIFT_LEFT_H
|
||
|
|
#define _LIBCPP___ALGORITHM_SHIFT_LEFT_H
|
||
|
|
|
||
|
|
#include <__algorithm/move.h>
|
||
|
|
#include <__config>
|
||
|
|
#include <__iterator/iterator_traits.h>
|
||
|
|
|
||
|
|
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
|
||
|
|
# pragma GCC system_header
|
||
|
|
#endif
|
||
|
|
|
||
|
|
_LIBCPP_BEGIN_NAMESPACE_STD
|
||
|
|
|
||
|
|
#if _LIBCPP_STD_VER >= 20
|
||
|
|
|
||
|
|
template <class _ForwardIterator>
|
||
|
|
inline _LIBCPP_INLINE_VISIBILITY constexpr
|
||
|
|
_ForwardIterator
|
||
|
|
shift_left(_ForwardIterator __first, _ForwardIterator __last,
|
||
|
|
typename iterator_traits<_ForwardIterator>::difference_type __n)
|
||
|
|
{
|
||
|
|
if (__n == 0) {
|
||
|
|
return __last;
|
||
|
|
}
|
||
|
|
|
||
|
|
_ForwardIterator __m = __first;
|
||
|
|
if constexpr (__has_random_access_iterator_category<_ForwardIterator>::value) {
|
||
|
|
if (__n >= __last - __first) {
|
||
|
|
return __first;
|
||
|
|
}
|
||
|
|
__m += __n;
|
||
|
|
} else {
|
||
|
|
for (; __n > 0; --__n) {
|
||
|
|
if (__m == __last) {
|
||
|
|
return __first;
|
||
|
|
}
|
||
|
|
++__m;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return _VSTD::move(__m, __last, __first);
|
||
|
|
}
|
||
|
|
|
||
|
|
#endif // _LIBCPP_STD_VER >= 20
|
||
|
|
|
||
|
|
_LIBCPP_END_NAMESPACE_STD
|
||
|
|
|
||
|
|
#endif // _LIBCPP___ALGORITHM_SHIFT_LEFT_H
|