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240 lines
8.0 KiB
240 lines
8.0 KiB
// Functions used by iterators -*- C++ -*-
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// Copyright (C) 2001-2021 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/*
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*
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* Copyright (c) 1994
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* Hewlett-Packard Company
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Hewlett-Packard Company makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*
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*
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* Copyright (c) 1996-1998
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*/
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/** @file bits/stl_iterator_base_funcs.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{iterator}
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*
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* This file contains all of the general iterator-related utility
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* functions, such as distance() and advance().
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*/
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#ifndef _STL_ITERATOR_BASE_FUNCS_H
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#define _STL_ITERATOR_BASE_FUNCS_H 1
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#pragma GCC system_header
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#include <bits/concept_check.h>
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#include <debug/assertions.h>
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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_GLIBCXX_BEGIN_NAMESPACE_CONTAINER
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// Forward declaration for the overloads of __distance.
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template <typename> struct _List_iterator;
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template <typename> struct _List_const_iterator;
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_GLIBCXX_END_NAMESPACE_CONTAINER
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template<typename _InputIterator>
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inline _GLIBCXX14_CONSTEXPR
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typename iterator_traits<_InputIterator>::difference_type
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__distance(_InputIterator __first, _InputIterator __last,
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input_iterator_tag)
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{
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// concept requirements
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__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
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typename iterator_traits<_InputIterator>::difference_type __n = 0;
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while (__first != __last)
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{
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++__first;
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++__n;
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}
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return __n;
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}
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template<typename _RandomAccessIterator>
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inline _GLIBCXX14_CONSTEXPR
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typename iterator_traits<_RandomAccessIterator>::difference_type
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__distance(_RandomAccessIterator __first, _RandomAccessIterator __last,
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random_access_iterator_tag)
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{
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// concept requirements
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__glibcxx_function_requires(_RandomAccessIteratorConcept<
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_RandomAccessIterator>)
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return __last - __first;
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}
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#if _GLIBCXX_USE_CXX11_ABI
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// Forward declaration because of the qualified call in distance.
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template<typename _Tp>
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ptrdiff_t
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__distance(_GLIBCXX_STD_C::_List_iterator<_Tp>,
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_GLIBCXX_STD_C::_List_iterator<_Tp>,
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input_iterator_tag);
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template<typename _Tp>
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ptrdiff_t
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__distance(_GLIBCXX_STD_C::_List_const_iterator<_Tp>,
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_GLIBCXX_STD_C::_List_const_iterator<_Tp>,
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input_iterator_tag);
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#endif
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/**
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* @brief A generalization of pointer arithmetic.
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* @param __first An input iterator.
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* @param __last An input iterator.
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* @return The distance between them.
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*
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* Returns @c n such that __first + n == __last. This requires
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* that @p __last must be reachable from @p __first. Note that @c
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* n may be negative.
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*
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* For random access iterators, this uses their @c + and @c - operations
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* and are constant time. For other %iterator classes they are linear time.
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*/
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template<typename _InputIterator>
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inline _GLIBCXX17_CONSTEXPR
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typename iterator_traits<_InputIterator>::difference_type
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distance(_InputIterator __first, _InputIterator __last)
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{
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// concept requirements -- taken care of in __distance
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return std::__distance(__first, __last,
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std::__iterator_category(__first));
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}
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template<typename _InputIterator, typename _Distance>
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inline _GLIBCXX14_CONSTEXPR void
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__advance(_InputIterator& __i, _Distance __n, input_iterator_tag)
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{
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// concept requirements
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__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
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__glibcxx_assert(__n >= 0);
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while (__n--)
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++__i;
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}
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template<typename _BidirectionalIterator, typename _Distance>
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inline _GLIBCXX14_CONSTEXPR void
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__advance(_BidirectionalIterator& __i, _Distance __n,
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bidirectional_iterator_tag)
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{
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// concept requirements
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__glibcxx_function_requires(_BidirectionalIteratorConcept<
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_BidirectionalIterator>)
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if (__n > 0)
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while (__n--)
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++__i;
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else
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while (__n++)
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--__i;
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}
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template<typename _RandomAccessIterator, typename _Distance>
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inline _GLIBCXX14_CONSTEXPR void
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__advance(_RandomAccessIterator& __i, _Distance __n,
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random_access_iterator_tag)
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{
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// concept requirements
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__glibcxx_function_requires(_RandomAccessIteratorConcept<
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_RandomAccessIterator>)
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if (__builtin_constant_p(__n) && __n == 1)
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++__i;
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else if (__builtin_constant_p(__n) && __n == -1)
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--__i;
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else
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__i += __n;
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}
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/**
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* @brief A generalization of pointer arithmetic.
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* @param __i An input iterator.
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* @param __n The @a delta by which to change @p __i.
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* @return Nothing.
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*
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* This increments @p i by @p n. For bidirectional and random access
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* iterators, @p __n may be negative, in which case @p __i is decremented.
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*
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* For random access iterators, this uses their @c + and @c - operations
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* and are constant time. For other %iterator classes they are linear time.
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*/
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template<typename _InputIterator, typename _Distance>
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inline _GLIBCXX17_CONSTEXPR void
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advance(_InputIterator& __i, _Distance __n)
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{
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// concept requirements -- taken care of in __advance
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typename iterator_traits<_InputIterator>::difference_type __d = __n;
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std::__advance(__i, __d, std::__iterator_category(__i));
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}
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#if __cplusplus >= 201103L
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template<typename _InputIterator>
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inline _GLIBCXX17_CONSTEXPR _InputIterator
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next(_InputIterator __x, typename
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iterator_traits<_InputIterator>::difference_type __n = 1)
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{
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// concept requirements
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__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
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std::advance(__x, __n);
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return __x;
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}
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template<typename _BidirectionalIterator>
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inline _GLIBCXX17_CONSTEXPR _BidirectionalIterator
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prev(_BidirectionalIterator __x, typename
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iterator_traits<_BidirectionalIterator>::difference_type __n = 1)
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{
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// concept requirements
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__glibcxx_function_requires(_BidirectionalIteratorConcept<
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_BidirectionalIterator>)
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std::advance(__x, -__n);
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return __x;
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}
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#endif // C++11
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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#endif /* _STL_ITERATOR_BASE_FUNCS_H */
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