1fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 2fe6060f1SDimitry Andric // 3fe6060f1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4fe6060f1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 5fe6060f1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6fe6060f1SDimitry Andric // 7fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 8fe6060f1SDimitry Andric 9fe6060f1SDimitry Andric #ifndef _LIBCPP___ALGORITHM_SHIFT_LEFT_H 10fe6060f1SDimitry Andric #define _LIBCPP___ALGORITHM_SHIFT_LEFT_H 11fe6060f1SDimitry Andric 12fe6060f1SDimitry Andric #include <__algorithm/move.h> 1304eeddc0SDimitry Andric #include <__config> 14fe6060f1SDimitry Andric #include <__iterator/iterator_traits.h> 15fe6060f1SDimitry Andric 16fe6060f1SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17fe6060f1SDimitry Andric # pragma GCC system_header 18fe6060f1SDimitry Andric #endif 19fe6060f1SDimitry Andric 20*b3edf446SDimitry Andric _LIBCPP_PUSH_MACROS 21*b3edf446SDimitry Andric #include <__undef_macros> 22*b3edf446SDimitry Andric 23fe6060f1SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 24fe6060f1SDimitry Andric 2506c3fb27SDimitry Andric #if _LIBCPP_STD_VER >= 20 26fe6060f1SDimitry Andric 27fe6060f1SDimitry Andric template <class _ForwardIterator> 28cb14a3feSDimitry Andric inline _LIBCPP_HIDE_FROM_ABI constexpr _ForwardIterator 29cb14a3feSDimitry Andric shift_left(_ForwardIterator __first, 30cb14a3feSDimitry Andric _ForwardIterator __last, 31cb14a3feSDimitry Andric typename iterator_traits<_ForwardIterator>::difference_type __n) { 32fe6060f1SDimitry Andric if (__n == 0) { 33fe6060f1SDimitry Andric return __last; 34fe6060f1SDimitry Andric } 35fe6060f1SDimitry Andric 36fe6060f1SDimitry Andric _ForwardIterator __m = __first; 3706c3fb27SDimitry Andric if constexpr (__has_random_access_iterator_category<_ForwardIterator>::value) { 38fe6060f1SDimitry Andric if (__n >= __last - __first) { 39fe6060f1SDimitry Andric return __first; 40fe6060f1SDimitry Andric } 41fe6060f1SDimitry Andric __m += __n; 42fe6060f1SDimitry Andric } else { 43fe6060f1SDimitry Andric for (; __n > 0; --__n) { 44fe6060f1SDimitry Andric if (__m == __last) { 45fe6060f1SDimitry Andric return __first; 46fe6060f1SDimitry Andric } 47fe6060f1SDimitry Andric ++__m; 48fe6060f1SDimitry Andric } 49fe6060f1SDimitry Andric } 505f757f3fSDimitry Andric return std::move(__m, __last, __first); 51fe6060f1SDimitry Andric } 52fe6060f1SDimitry Andric 5306c3fb27SDimitry Andric #endif // _LIBCPP_STD_VER >= 20 54fe6060f1SDimitry Andric 55fe6060f1SDimitry Andric _LIBCPP_END_NAMESPACE_STD 56fe6060f1SDimitry Andric 57*b3edf446SDimitry Andric _LIBCPP_POP_MACROS 58*b3edf446SDimitry Andric 59fe6060f1SDimitry Andric #endif // _LIBCPP___ALGORITHM_SHIFT_LEFT_H 60