stl_iterator_base_types.h
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// Types used in iterator implementation -*- C++ -*-
// Copyright (C) 2001-2021 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_types.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 types,
* such as iterator_traits and struct iterator.
*/
#ifndef _STL_ITERATOR_BASE_TYPES_H
#define _STL_ITERATOR_BASE_TYPES_H 1
#pragma GCC system_header
#include <bits/c++config.h>
#if __cplusplus >= 201103L
# include <type_traits> // For __void_t, is_convertible
#endif
#if __cplusplus > 201703L && __cpp_concepts >= 201907L
# include <bits/iterator_concepts.h>
#endif
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/**
* @defgroup iterators Iterators
* Abstractions for uniform iterating through various underlying types.
*/
///@{
/**
* @defgroup iterator_tags Iterator Tags
* These are empty types, used to distinguish different iterators. The
* distinction is not made by what they contain, but simply by what they
* are. Different underlying algorithms can then be used based on the
* different operations supported by different iterator types.
*/
///@{
/// Marking input iterators.
struct input_iterator_tag { };
/// Marking output iterators.
struct output_iterator_tag { };
/// Forward iterators support a superset of input iterator operations.
struct forward_iterator_tag : public input_iterator_tag { };
/// Bidirectional iterators support a superset of forward iterator
/// operations.
struct bidirectional_iterator_tag : public forward_iterator_tag { };
/// Random-access iterators support a superset of bidirectional
/// iterator operations.
struct random_access_iterator_tag : public bidirectional_iterator_tag { };
#if __cplusplus > 201703L
/// Contiguous iterators point to objects stored contiguously in memory.
struct contiguous_iterator_tag : public random_access_iterator_tag { };
#endif
///@}
/**
* @brief Common %iterator class.
*
* This class does nothing but define nested typedefs. %Iterator classes
* can inherit from this class to save some work. The typedefs are then
* used in specializations and overloading.
*
* In particular, there are no default implementations of requirements
* such as @c operator++ and the like. (How could there be?)
*/
template<typename _Category, typename _Tp, typename _Distance = ptrdiff_t,
typename _Pointer = _Tp*, typename _Reference = _Tp&>
struct iterator
{
/// One of the @link iterator_tags tag types@endlink.
typedef _Category iterator_category;
/// The type "pointed to" by the iterator.
typedef _Tp value_type;
/// Distance between iterators is represented as this type.
typedef _Distance difference_type;
/// This type represents a pointer-to-value_type.
typedef _Pointer pointer;
/// This type represents a reference-to-value_type.
typedef _Reference reference;
};
/**
* @brief Traits class for iterators.
*
* This class does nothing but define nested typedefs. The general
* version simply @a forwards the nested typedefs from the Iterator
* argument. Specialized versions for pointers and pointers-to-const
* provide tighter, more correct semantics.
*/
template<typename _Iterator>
struct iterator_traits;
#if __cplusplus >= 201103L
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 2408. SFINAE-friendly common_type/iterator_traits is missing in C++14
template<typename _Iterator, typename = __void_t<>>
struct __iterator_traits { };
#if ! __cpp_lib_concepts
template<typename _Iterator>
struct __iterator_traits<_Iterator,
__void_t<typename _Iterator::iterator_category,
typename _Iterator::value_type,
typename _Iterator::difference_type,
typename _Iterator::pointer,
typename _Iterator::reference>>
{
typedef typename _Iterator::iterator_category iterator_category;
typedef typename _Iterator::value_type value_type;
typedef typename _Iterator::difference_type difference_type;
typedef typename _Iterator::pointer pointer;
typedef typename _Iterator::reference reference;
};
#endif // ! concepts
template<typename _Iterator>
struct iterator_traits
: public __iterator_traits<_Iterator> { };
#else // ! C++11
template<typename _Iterator>
struct iterator_traits
{
typedef typename _Iterator::iterator_category iterator_category;
typedef typename _Iterator::value_type value_type;
typedef typename _Iterator::difference_type difference_type;
typedef typename _Iterator::pointer pointer;
typedef typename _Iterator::reference reference;
};
#endif // C++11
#if __cplusplus > 201703L
/// Partial specialization for object pointer types.
template<typename _Tp>
#if __cpp_concepts >= 201907L
requires is_object_v<_Tp>
#endif
struct iterator_traits<_Tp*>
{
using iterator_concept = contiguous_iterator_tag;
using iterator_category = random_access_iterator_tag;
using value_type = remove_cv_t<_Tp>;
using difference_type = ptrdiff_t;
using pointer = _Tp*;
using reference = _Tp&;
};
#else
/// Partial specialization for pointer types.
template<typename _Tp>
struct iterator_traits<_Tp*>
{
typedef random_access_iterator_tag iterator_category;
typedef _Tp value_type;
typedef ptrdiff_t difference_type;
typedef _Tp* pointer;
typedef _Tp& reference;
};
/// Partial specialization for const pointer types.
template<typename _Tp>
struct iterator_traits<const _Tp*>
{
typedef random_access_iterator_tag iterator_category;
typedef _Tp value_type;
typedef ptrdiff_t difference_type;
typedef const _Tp* pointer;
typedef const _Tp& reference;
};
#endif
/**
* This function is not a part of the C++ standard but is syntactic
* sugar for internal library use only.
*/
template<typename _Iter>
inline _GLIBCXX_CONSTEXPR
typename iterator_traits<_Iter>::iterator_category
__iterator_category(const _Iter&)
{ return typename iterator_traits<_Iter>::iterator_category(); }
///@}
#if __cplusplus >= 201103L
template<typename _Iter>
using __iterator_category_t
= typename iterator_traits<_Iter>::iterator_category;
template<typename _InIter>
using _RequireInputIter =
__enable_if_t<is_convertible<__iterator_category_t<_InIter>,
input_iterator_tag>::value>;
template<typename _It,
typename _Cat = __iterator_category_t<_It>>
struct __is_random_access_iter
: is_base_of<random_access_iterator_tag, _Cat>
{
typedef is_base_of<random_access_iterator_tag, _Cat> _Base;
enum { __value = _Base::value };
};
#else
template<typename _It, typename _Traits = iterator_traits<_It>,
typename _Cat = typename _Traits::iterator_category>
struct __is_random_access_iter
{ enum { __value = __is_base_of(random_access_iterator_tag, _Cat) }; };
#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif /* _STL_ITERATOR_BASE_TYPES_H */
type_traits
iterator_concepts.h
c++config.h
std::__iterator_category
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
Definition stl_iterator_base_types.h:238
std
ISO C++ entities toplevel namespace is std.
std::iterator_traits
Traits class for iterators.
Definition stl_iterator_base_types.h:178
std::input_iterator_tag
Marking input iterators.
Definition stl_iterator_base_types.h:93
std::output_iterator_tag
Marking output iterators.
Definition stl_iterator_base_types.h:96
std::forward_iterator_tag
Forward iterators support a superset of input iterator operations.
Definition stl_iterator_base_types.h:99
std::bidirectional_iterator_tag
Bidirectional iterators support a superset of forward iterator operations.
Definition stl_iterator_base_types.h:103
std::random_access_iterator_tag
Random-access iterators support a superset of bidirectional iterator operations.
Definition stl_iterator_base_types.h:107
std::iterator
Common iterator class.
Definition stl_iterator_base_types.h:128
std::iterator::iterator_category
_Category iterator_category
One of the tag types.
Definition stl_iterator_base_types.h:130
std::iterator::pointer
_Pointer pointer
This type represents a pointer-to-value_type.
Definition stl_iterator_base_types.h:136
std::iterator::difference_type
_Distance difference_type
Distance between iterators is represented as this type.
Definition stl_iterator_base_types.h:134
std::iterator::reference
_Reference reference
This type represents a reference-to-value_type.
Definition stl_iterator_base_types.h:138
std::iterator::value_type
_Tp value_type
The type "pointed to" by the iterator.
Definition stl_iterator_base_types.h:132
std::auto_ptr_ref
Definition auto_ptr.h:49