176d0caaeSpatrick // -*- C++ -*- 276d0caaeSpatrick //===----------------------------------------------------------------------===// 376d0caaeSpatrick // 476d0caaeSpatrick // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 576d0caaeSpatrick // See https://llvm.org/LICENSE.txt for license information. 676d0caaeSpatrick // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 776d0caaeSpatrick // 876d0caaeSpatrick //===----------------------------------------------------------------------===// 976d0caaeSpatrick 1076d0caaeSpatrick #ifndef _LIBCPP___ITERATOR_PREV_H 1176d0caaeSpatrick #define _LIBCPP___ITERATOR_PREV_H 1276d0caaeSpatrick 13*4bdff4beSrobert #include <__assert> 1476d0caaeSpatrick #include <__config> 1576d0caaeSpatrick #include <__iterator/advance.h> 1676d0caaeSpatrick #include <__iterator/concepts.h> 1776d0caaeSpatrick #include <__iterator/incrementable_traits.h> 1876d0caaeSpatrick #include <__iterator/iterator_traits.h> 19*4bdff4beSrobert #include <__type_traits/enable_if.h> 2076d0caaeSpatrick 2176d0caaeSpatrick #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 2276d0caaeSpatrick # pragma GCC system_header 2376d0caaeSpatrick #endif 2476d0caaeSpatrick 2576d0caaeSpatrick _LIBCPP_BEGIN_NAMESPACE_STD 2676d0caaeSpatrick 2776d0caaeSpatrick template <class _InputIter> 28*4bdff4beSrobert inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_SINCE_CXX17 2976d0caaeSpatrick typename enable_if<__is_cpp17_input_iterator<_InputIter>::value, _InputIter>::type 3076d0caaeSpatrick prev(_InputIter __x, typename iterator_traits<_InputIter>::difference_type __n = 1) { 3176d0caaeSpatrick _LIBCPP_ASSERT(__n <= 0 || __is_cpp17_bidirectional_iterator<_InputIter>::value, 3276d0caaeSpatrick "Attempt to prev(it, n) with a positive n on a non-bidirectional iterator"); 3376d0caaeSpatrick _VSTD::advance(__x, -__n); 3476d0caaeSpatrick return __x; 3576d0caaeSpatrick } 3676d0caaeSpatrick 37*4bdff4beSrobert #if _LIBCPP_STD_VER > 17 38*4bdff4beSrobert 39*4bdff4beSrobert // [range.iter.op.prev] 4076d0caaeSpatrick 4176d0caaeSpatrick namespace ranges { 42*4bdff4beSrobert namespace __prev { 4376d0caaeSpatrick 44*4bdff4beSrobert struct __fn { 4576d0caaeSpatrick template <bidirectional_iterator _Ip> 4676d0caaeSpatrick _LIBCPP_HIDE_FROM_ABI operator__fn4776d0caaeSpatrick constexpr _Ip operator()(_Ip __x) const { 4876d0caaeSpatrick --__x; 4976d0caaeSpatrick return __x; 5076d0caaeSpatrick } 5176d0caaeSpatrick 5276d0caaeSpatrick template <bidirectional_iterator _Ip> 5376d0caaeSpatrick _LIBCPP_HIDE_FROM_ABI operator__fn5476d0caaeSpatrick constexpr _Ip operator()(_Ip __x, iter_difference_t<_Ip> __n) const { 5576d0caaeSpatrick ranges::advance(__x, -__n); 5676d0caaeSpatrick return __x; 5776d0caaeSpatrick } 5876d0caaeSpatrick 5976d0caaeSpatrick template <bidirectional_iterator _Ip> operator__fn60*4bdff4beSrobert _LIBCPP_HIDE_FROM_ABI constexpr _Ip operator()(_Ip __x, iter_difference_t<_Ip> __n, _Ip __bound_iter) const { 61*4bdff4beSrobert ranges::advance(__x, -__n, __bound_iter); 6276d0caaeSpatrick return __x; 6376d0caaeSpatrick } 6476d0caaeSpatrick }; 6576d0caaeSpatrick 66*4bdff4beSrobert } // namespace __prev 67*4bdff4beSrobert 68*4bdff4beSrobert inline namespace __cpo { 69*4bdff4beSrobert inline constexpr auto prev = __prev::__fn{}; 70*4bdff4beSrobert } // namespace __cpo 7176d0caaeSpatrick } // namespace ranges 7276d0caaeSpatrick 73*4bdff4beSrobert #endif // _LIBCPP_STD_VER > 17 7476d0caaeSpatrick 7576d0caaeSpatrick _LIBCPP_END_NAMESPACE_STD 7676d0caaeSpatrick 7776d0caaeSpatrick #endif // _LIBCPP___ITERATOR_PREV_H 78