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1// -*- C++ -*-2//===----------------------------------------------------------------------===//3//4// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.5// See https://llvm.org/LICENSE.txt for license information.6// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception7//8//===----------------------------------------------------------------------===//9 10#ifndef _LIBCPP___ITERATOR_DISTANCE_H11#define _LIBCPP___ITERATOR_DISTANCE_H12 13#include <__algorithm/for_each_segment.h>14#include <__concepts/same_as.h>15#include <__config>16#include <__iterator/concepts.h>17#include <__iterator/incrementable_traits.h>18#include <__iterator/iterator_traits.h>19#include <__iterator/segmented_iterator.h>20#include <__ranges/access.h>21#include <__ranges/concepts.h>22#include <__ranges/size.h>23#include <__type_traits/decay.h>24#include <__type_traits/enable_if.h>25#include <__type_traits/remove_cvref.h>26#include <__utility/move.h>27 28#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)29# pragma GCC system_header30#endif31 32_LIBCPP_PUSH_MACROS33#include <__undef_macros>34 35_LIBCPP_BEGIN_NAMESPACE_STD36 37#if _LIBCPP_STD_VER >= 2038template <class _Iter>39using __iter_distance_t _LIBCPP_NODEBUG = std::iter_difference_t<_Iter>;40#else41template <class _Iter>42using __iter_distance_t _LIBCPP_NODEBUG = typename iterator_traits<_Iter>::difference_type;43#endif44 45template <class _RandIter, __enable_if_t<__has_random_access_iterator_category<_RandIter>::value, int> = 0>46inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 __iter_distance_t<_RandIter>47__distance(_RandIter __first, _RandIter __last) {48 return __last - __first;49}50 51template <class _InputIter, class _Sent>52inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 __iter_distance_t<_InputIter>53__distance(_InputIter __first, _Sent __last) {54 __iter_distance_t<_InputIter> __r(0);55#if _LIBCPP_STD_VER >= 2056 if constexpr (same_as<_InputIter, _Sent> && __is_segmented_iterator_v<_InputIter>) {57 std::__for_each_segment(__first, __last, [&__r](auto __lfirst, auto __llast) {58 __r += std::__distance(__lfirst, __llast);59 });60 } else61#endif62 {63 for (; __first != __last; ++__first)64 ++__r;65 }66 return __r;67}68 69template <class _InputIter>70inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 typename iterator_traits<_InputIter>::difference_type71distance(_InputIter __first, _InputIter __last) {72 return std::__distance(__first, __last);73}74 75#if _LIBCPP_STD_VER >= 2076 77// [range.iter.op.distance]78 79namespace ranges {80struct __distance {81 template <class _Ip, sentinel_for<_Ip> _Sp>82 requires(!sized_sentinel_for<_Sp, _Ip>)83 _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Ip> operator()(_Ip __first, _Sp __last) const {84 return std::__distance(std::move(__first), std::move(__last));85 }86 87 template <class _Ip, sized_sentinel_for<decay_t<_Ip>> _Sp>88 _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Ip> operator()(_Ip&& __first, _Sp __last) const {89 if constexpr (sized_sentinel_for<_Sp, __remove_cvref_t<_Ip>>) {90 return __last - __first;91 } else {92 return __last - decay_t<_Ip>(__first);93 }94 }95 96 template <range _Rp>97 _LIBCPP_HIDE_FROM_ABI constexpr range_difference_t<_Rp> operator()(_Rp&& __r) const {98 if constexpr (sized_range<_Rp>) {99 return static_cast<range_difference_t<_Rp>>(ranges::size(__r));100 } else {101 return operator()(ranges::begin(__r), ranges::end(__r));102 }103 }104};105 106inline namespace __cpo {107inline constexpr auto distance = __distance{};108} // namespace __cpo109} // namespace ranges110 111#endif // _LIBCPP_STD_VER >= 20112 113_LIBCPP_END_NAMESPACE_STD114 115_LIBCPP_POP_MACROS116 117#endif // _LIBCPP___ITERATOR_DISTANCE_H118