stl_iterator_base_funcs.h
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// Functions used by iterators -*- C++ -*-
// Copyright (C) 2001-2023 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>
#include <bits/stl_iterator_base_types.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>
__attribute__((__always_inline__))
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
#if __cplusplus >= 201103L
// Give better error if std::distance called with a non-Cpp17InputIterator.
template<typename _OutputIterator>
void
__distance(_OutputIterator, _OutputIterator, output_iterator_tag) = delete;
#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>
_GLIBCXX_NODISCARD __attribute__((__always_inline__))
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;
}
#if __cplusplus >= 201103L
// Give better error if std::advance called with a non-Cpp17InputIterator.
template<typename _OutputIterator, typename _Distance>
void
__advance(_OutputIterator&, _Distance, output_iterator_tag) = delete;
#endif
/**
* @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>
__attribute__((__always_inline__))
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>
_GLIBCXX_NODISCARD [[__gnu__::__always_inline__]]
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>
_GLIBCXX_NODISCARD [[__gnu__::__always_inline__]]
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 */
concept_check.h
stl_iterator_base_types.h
assertions.h
std::__iterator_category
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
Definition stl_iterator_base_types.h:239
std
ISO C++ entities toplevel namespace is std.
std::distance
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
Definition stl_iterator_base_funcs.h:148
std::advance
constexpr void advance(_InputIterator &__i, _Distance __n)
A generalization of pointer arithmetic.
Definition stl_iterator_base_funcs.h:220
std::iterator_traits
Traits class for iterators.
Definition stl_iterator_base_types.h:178
std::auto_ptr_ref
Definition auto_ptr.h:49