1fe6060f1SDimitry Andric // -*- C++ -*- 2fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 3fe6060f1SDimitry Andric // 4fe6060f1SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 5fe6060f1SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 6fe6060f1SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 7fe6060f1SDimitry Andric // 8fe6060f1SDimitry Andric //===----------------------------------------------------------------------===// 9fe6060f1SDimitry Andric 10fe6060f1SDimitry Andric #ifndef _LIBCPP___ITERATOR_DISTANCE_H 11fe6060f1SDimitry Andric #define _LIBCPP___ITERATOR_DISTANCE_H 12fe6060f1SDimitry Andric 13fe6060f1SDimitry Andric #include <__config> 141fd87a68SDimitry Andric #include <__iterator/concepts.h> 151fd87a68SDimitry Andric #include <__iterator/incrementable_traits.h> 16fe6060f1SDimitry Andric #include <__iterator/iterator_traits.h> 171fd87a68SDimitry Andric #include <__ranges/access.h> 181fd87a68SDimitry Andric #include <__ranges/concepts.h> 191fd87a68SDimitry Andric #include <__ranges/size.h> 20bdd1243dSDimitry Andric #include <__type_traits/decay.h> 21bdd1243dSDimitry Andric #include <__type_traits/remove_cvref.h> 22fe6060f1SDimitry Andric 23fe6060f1SDimitry Andric #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 24fe6060f1SDimitry Andric # pragma GCC system_header 25fe6060f1SDimitry Andric #endif 26fe6060f1SDimitry Andric 27fe6060f1SDimitry Andric _LIBCPP_BEGIN_NAMESPACE_STD 28fe6060f1SDimitry Andric 29fe6060f1SDimitry Andric template <class _InputIter> 30*cb14a3feSDimitry Andric inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 typename iterator_traits<_InputIter>::difference_type 31*cb14a3feSDimitry Andric __distance(_InputIter __first, _InputIter __last, input_iterator_tag) { 32fe6060f1SDimitry Andric typename iterator_traits<_InputIter>::difference_type __r(0); 33fe6060f1SDimitry Andric for (; __first != __last; ++__first) 34fe6060f1SDimitry Andric ++__r; 35fe6060f1SDimitry Andric return __r; 36fe6060f1SDimitry Andric } 37fe6060f1SDimitry Andric 38fe6060f1SDimitry Andric template <class _RandIter> 39*cb14a3feSDimitry Andric inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 typename iterator_traits<_RandIter>::difference_type 40*cb14a3feSDimitry Andric __distance(_RandIter __first, _RandIter __last, random_access_iterator_tag) { 41fe6060f1SDimitry Andric return __last - __first; 42fe6060f1SDimitry Andric } 43fe6060f1SDimitry Andric 44fe6060f1SDimitry Andric template <class _InputIter> 45*cb14a3feSDimitry Andric inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX17 typename iterator_traits<_InputIter>::difference_type 46*cb14a3feSDimitry Andric distance(_InputIter __first, _InputIter __last) { 475f757f3fSDimitry Andric return std::__distance(__first, __last, typename iterator_traits<_InputIter>::iterator_category()); 48fe6060f1SDimitry Andric } 49fe6060f1SDimitry Andric 5006c3fb27SDimitry Andric #if _LIBCPP_STD_VER >= 20 511fd87a68SDimitry Andric 521fd87a68SDimitry Andric // [range.iter.op.distance] 531fd87a68SDimitry Andric 541fd87a68SDimitry Andric namespace ranges { 551fd87a68SDimitry Andric namespace __distance { 561fd87a68SDimitry Andric 571fd87a68SDimitry Andric struct __fn { 581fd87a68SDimitry Andric template <class _Ip, sentinel_for<_Ip> _Sp> 591fd87a68SDimitry Andric requires(!sized_sentinel_for<_Sp, _Ip>) 60*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Ip> operator()(_Ip __first, _Sp __last) const { 611fd87a68SDimitry Andric iter_difference_t<_Ip> __n = 0; 621fd87a68SDimitry Andric while (__first != __last) { 631fd87a68SDimitry Andric ++__first; 641fd87a68SDimitry Andric ++__n; 651fd87a68SDimitry Andric } 661fd87a68SDimitry Andric return __n; 671fd87a68SDimitry Andric } 681fd87a68SDimitry Andric 691fd87a68SDimitry Andric template <class _Ip, sized_sentinel_for<decay_t<_Ip>> _Sp> 70*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI constexpr iter_difference_t<_Ip> operator()(_Ip&& __first, _Sp __last) const { 71bdd1243dSDimitry Andric if constexpr (sized_sentinel_for<_Sp, __remove_cvref_t<_Ip>>) { 721fd87a68SDimitry Andric return __last - __first; 731fd87a68SDimitry Andric } else { 741fd87a68SDimitry Andric return __last - decay_t<_Ip>(__first); 751fd87a68SDimitry Andric } 761fd87a68SDimitry Andric } 771fd87a68SDimitry Andric 781fd87a68SDimitry Andric template <range _Rp> 79*cb14a3feSDimitry Andric _LIBCPP_HIDE_FROM_ABI constexpr range_difference_t<_Rp> operator()(_Rp&& __r) const { 801fd87a68SDimitry Andric if constexpr (sized_range<_Rp>) { 811fd87a68SDimitry Andric return static_cast<range_difference_t<_Rp>>(ranges::size(__r)); 821fd87a68SDimitry Andric } else { 831fd87a68SDimitry Andric return operator()(ranges::begin(__r), ranges::end(__r)); 841fd87a68SDimitry Andric } 851fd87a68SDimitry Andric } 861fd87a68SDimitry Andric }; 871fd87a68SDimitry Andric 881fd87a68SDimitry Andric } // namespace __distance 891fd87a68SDimitry Andric 901fd87a68SDimitry Andric inline namespace __cpo { 911fd87a68SDimitry Andric inline constexpr auto distance = __distance::__fn{}; 921fd87a68SDimitry Andric } // namespace __cpo 931fd87a68SDimitry Andric } // namespace ranges 941fd87a68SDimitry Andric 9506c3fb27SDimitry Andric #endif // _LIBCPP_STD_VER >= 20 961fd87a68SDimitry Andric 97fe6060f1SDimitry Andric _LIBCPP_END_NAMESPACE_STD 98fe6060f1SDimitry Andric 99fe6060f1SDimitry Andric #endif // _LIBCPP___ITERATOR_DISTANCE_H 100