Editing: stl_iterator_base_funcs.h
// Functions used by iterators -*- C++ -*- // Copyright (C) 2001-2018 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /* * * Copyright (c) 1994 * Hewlett-Packard Company * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Hewlett-Packard Company makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. * * * Copyright (c) 1996-1998 * Silicon Graphics Computer Systems, Inc. * * Permission to use, copy, modify, distribute and sell this software * and its documentation for any purpose is hereby granted without fee, * provided that the above copyright notice appear in all copies and * that both that copyright notice and this permission notice appear * in supporting documentation. Silicon Graphics makes no * representations about the suitability of this software for any * purpose. It is provided "as is" without express or implied warranty. */ /** @file bits/stl_iterator_base_funcs.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{iterator} * * This file contains all of the general iterator-related utility * functions, such as distance() and advance(). */ #ifndef _STL_ITERATOR_BASE_FUNCS_H #define _STL_ITERATOR_BASE_FUNCS_H 1 #pragma GCC system_header #include <bits/concept_check.h> #include <debug/assertions.h> namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION _GLIBCXX_BEGIN_NAMESPACE_CONTAINER // Forward declaration for the overloads of __distance. template <typename> struct _List_iterator; template <typename> struct _List_const_iterator; _GLIBCXX_END_NAMESPACE_CONTAINER template<typename _InputIterator> inline _GLIBCXX14_CONSTEXPR typename iterator_traits<_InputIterator>::difference_type __distance(_InputIterator __first, _InputIterator __last, input_iterator_tag) { // concept requirements __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) typename iterator_traits<_InputIterator>::difference_type __n = 0; while (__first != __last) { ++__first; ++__n; } return __n; } template<typename _RandomAccessIterator> inline _GLIBCXX14_CONSTEXPR typename iterator_traits<_RandomAccessIterator>::difference_type __distance(_RandomAccessIterator __first, _RandomAccessIterator __last, random_access_iterator_tag) { // concept requirements __glibcxx_function_requires(_RandomAccessIteratorConcept< _RandomAccessIterator>) return __last - __first; } #if _GLIBCXX_USE_CXX11_ABI // Forward declaration because of the qualified call in distance. template<typename _Tp> ptrdiff_t __distance(_GLIBCXX_STD_C::_List_iterator<_Tp>, _GLIBCXX_STD_C::_List_iterator<_Tp>, input_iterator_tag); template<typename _Tp> ptrdiff_t __distance(_GLIBCXX_STD_C::_List_const_iterator<_Tp>, _GLIBCXX_STD_C::_List_const_iterator<_Tp>, input_iterator_tag); #endif /** * @brief A generalization of pointer arithmetic. * @param __first An input iterator. * @param __last An input iterator. * @return The distance between them. * * Returns @c n such that __first + n == __last. This requires * that @p __last must be reachable from @p __first. Note that @c * n may be negative. * * For random access iterators, this uses their @c + and @c - operations * and are constant time. For other %iterator classes they are linear time. */ template<typename _InputIterator> inline _GLIBCXX17_CONSTEXPR typename iterator_traits<_InputIterator>::difference_type distance(_InputIterator __first, _InputIterator __last) { // concept requirements -- taken care of in __distance return std::__distance(__first, __last, std::__iterator_category(__first)); } template<typename _InputIterator, typename _Distance> inline _GLIBCXX14_CONSTEXPR void __advance(_InputIterator& __i, _Distance __n, input_iterator_tag) { // concept requirements __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) __glibcxx_assert(__n >= 0); while (__n--) ++__i; } template<typename _BidirectionalIterator, typename _Distance> inline _GLIBCXX14_CONSTEXPR void __advance(_BidirectionalIterator& __i, _Distance __n, bidirectional_iterator_tag) { // concept requirements __glibcxx_function_requires(_BidirectionalIteratorConcept< _BidirectionalIterator>) if (__n > 0) while (__n--) ++__i; else while (__n++) --__i; } template<typename _RandomAccessIterator, typename _Distance> inline _GLIBCXX14_CONSTEXPR void __advance(_RandomAccessIterator& __i, _Distance __n, random_access_iterator_tag) { // concept requirements __glibcxx_function_requires(_RandomAccessIteratorConcept< _RandomAccessIterator>) if (__builtin_constant_p(__n) && __n == 1) ++__i; else if (__builtin_constant_p(__n) && __n == -1) --__i; else __i += __n; } /** * @brief A generalization of pointer arithmetic. * @param __i An input iterator. * @param __n The @a delta by which to change @p __i. * @return Nothing. * * This increments @p i by @p n. For bidirectional and random access * iterators, @p __n may be negative, in which case @p __i is decremented. * * For random access iterators, this uses their @c + and @c - operations * and are constant time. For other %iterator classes they are linear time. */ template<typename _InputIterator, typename _Distance> inline _GLIBCXX17_CONSTEXPR void advance(_InputIterator& __i, _Distance __n) { // concept requirements -- taken care of in __advance typename iterator_traits<_InputIterator>::difference_type __d = __n; std::__advance(__i, __d, std::__iterator_category(__i)); } #if __cplusplus >= 201103L template<typename _InputIterator> inline _GLIBCXX17_CONSTEXPR _InputIterator next(_InputIterator __x, typename iterator_traits<_InputIterator>::difference_type __n = 1) { // concept requirements __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) std::advance(__x, __n); return __x; } template<typename _BidirectionalIterator> inline _GLIBCXX17_CONSTEXPR _BidirectionalIterator prev(_BidirectionalIterator __x, typename iterator_traits<_BidirectionalIterator>::difference_type __n = 1) { // concept requirements __glibcxx_function_requires(_BidirectionalIteratorConcept< _BidirectionalIterator>) std::advance(__x, -__n); return __x; } #endif // C++11 _GLIBCXX_END_NAMESPACE_VERSION } // namespace #endif /* _STL_ITERATOR_BASE_FUNCS_H */
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