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-exception 7 // 8 //===----------------------------------------------------------------------===// 9 10 #ifndef _LIBCPP___ITERATOR_DISTANCE_H 11 #define _LIBCPP___ITERATOR_DISTANCE_H 12 13 #include <__config> 14 #include <__iterator/iterator_traits.h> 15 16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 17 #pragma GCC system_header 18 #endif 19 20 _LIBCPP_BEGIN_NAMESPACE_STD 21 22 template <class _InputIter> 23 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 24 typename iterator_traits<_InputIter>::difference_type 25 __distance(_InputIter __first, _InputIter __last, input_iterator_tag) 26 { 27 typename iterator_traits<_InputIter>::difference_type __r(0); 28 for (; __first != __last; ++__first) 29 ++__r; 30 return __r; 31 } 32 33 template <class _RandIter> 34 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 35 typename iterator_traits<_RandIter>::difference_type 36 __distance(_RandIter __first, _RandIter __last, random_access_iterator_tag) 37 { 38 return __last - __first; 39 } 40 41 template <class _InputIter> 42 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX14 43 typename iterator_traits<_InputIter>::difference_type 44 distance(_InputIter __first, _InputIter __last) 45 { 46 return _VSTD::__distance(__first, __last, typename iterator_traits<_InputIter>::iterator_category()); 47 } 48 49 _LIBCPP_END_NAMESPACE_STD 50 51 #endif // _LIBCPP___ITERATOR_DISTANCE_H 52