📄 stl_list.h
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// List implementation -*- C++ -*-// Copyright (C) 2001, 2002, 2003, 2004, 2005 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 2, 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.// You should have received a copy of the GNU General Public License along// with this library; see the file COPYING. If not, write to the Free// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,// USA.// As a special exception, you may use this file as part of a free software// library without restriction. Specifically, if other files instantiate// templates or use macros or inline functions from this file, or you compile// this file and link it with other files to produce an executable, this// file does not by itself cause the resulting executable to be covered by// the GNU General Public License. This exception does not however// invalidate any other reasons why the executable file might be covered by// the GNU General Public License./* * * 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) 1996,1997 * 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 stl_list.h * This is an internal header file, included by other library headers. * You should not attempt to use it directly. */#ifndef _LIST_H#define _LIST_H 1#include <bits/concept_check.h>namespace _GLIBCXX_STD{ // Supporting structures are split into common and templated types; the // latter publicly inherits from the former in an effort to reduce code // duplication. This results in some "needless" static_cast'ing later on, // but it's all safe downcasting. /// @if maint Common part of a node in the %list. @endif struct _List_node_base { _List_node_base* _M_next; ///< Self-explanatory _List_node_base* _M_prev; ///< Self-explanatory static void swap(_List_node_base& __x, _List_node_base& __y); void transfer(_List_node_base * const __first, _List_node_base * const __last); void reverse(); void hook(_List_node_base * const __position); void unhook(); }; /// @if maint An actual node in the %list. @endif template<typename _Tp> struct _List_node : public _List_node_base { _Tp _M_data; ///< User's data. }; /** * @brief A list::iterator. * * @if maint * All the functions are op overloads. * @endif */ template<typename _Tp> struct _List_iterator { typedef _List_iterator<_Tp> _Self; typedef _List_node<_Tp> _Node; typedef ptrdiff_t difference_type; typedef bidirectional_iterator_tag iterator_category; typedef _Tp value_type; typedef _Tp* pointer; typedef _Tp& reference; _List_iterator() : _M_node() { } _List_iterator(_List_node_base* __x) : _M_node(__x) { } // Must downcast from List_node_base to _List_node to get to _M_data. reference operator*() const { return static_cast<_Node*>(_M_node)->_M_data; } pointer operator->() const { return &static_cast<_Node*>(_M_node)->_M_data; } _Self& operator++() { _M_node = _M_node->_M_next; return *this; } _Self operator++(int) { _Self __tmp = *this; _M_node = _M_node->_M_next; return __tmp; } _Self& operator--() { _M_node = _M_node->_M_prev; return *this; } _Self operator--(int) { _Self __tmp = *this; _M_node = _M_node->_M_prev; return __tmp; } bool operator==(const _Self& __x) const { return _M_node == __x._M_node; } bool operator!=(const _Self& __x) const { return _M_node != __x._M_node; } // The only member points to the %list element. _List_node_base* _M_node; }; /** * @brief A list::const_iterator. * * @if maint * All the functions are op overloads. * @endif */ template<typename _Tp> struct _List_const_iterator { typedef _List_const_iterator<_Tp> _Self; typedef const _List_node<_Tp> _Node; typedef _List_iterator<_Tp> iterator; typedef ptrdiff_t difference_type; typedef bidirectional_iterator_tag iterator_category; typedef _Tp value_type; typedef const _Tp* pointer; typedef const _Tp& reference; _List_const_iterator() : _M_node() { } _List_const_iterator(const _List_node_base* __x) : _M_node(__x) { } _List_const_iterator(const iterator& __x) : _M_node(__x._M_node) { } // Must downcast from List_node_base to _List_node to get to // _M_data. reference operator*() const { return static_cast<_Node*>(_M_node)->_M_data; } pointer operator->() const { return &static_cast<_Node*>(_M_node)->_M_data; } _Self& operator++() { _M_node = _M_node->_M_next; return *this; } _Self operator++(int) { _Self __tmp = *this; _M_node = _M_node->_M_next; return __tmp; } _Self& operator--() { _M_node = _M_node->_M_prev; return *this; } _Self operator--(int) { _Self __tmp = *this; _M_node = _M_node->_M_prev; return __tmp; } bool operator==(const _Self& __x) const { return _M_node == __x._M_node; } bool operator!=(const _Self& __x) const { return _M_node != __x._M_node; } // The only member points to the %list element. const _List_node_base* _M_node; }; template<typename _Val> inline bool operator==(const _List_iterator<_Val>& __x, const _List_const_iterator<_Val>& __y) { return __x._M_node == __y._M_node; } template<typename _Val> inline bool operator!=(const _List_iterator<_Val>& __x, const _List_const_iterator<_Val>& __y) { return __x._M_node != __y._M_node; } /** * @if maint * See bits/stl_deque.h's _Deque_base for an explanation. * @endif */ template<typename _Tp, typename _Alloc> class _List_base { protected: // NOTA BENE // The stored instance is not actually of "allocator_type"'s // type. Instead we rebind the type to // Allocator<List_node<Tp>>, which according to [20.1.5]/4 // should probably be the same. List_node<Tp> is not the same // size as Tp (it's two pointers larger), and specializations on // Tp may go unused because List_node<Tp> is being bound // instead. // // We put this to the test in the constructors and in // get_allocator, where we use conversions between // allocator_type and _Node_Alloc_type. The conversion is // required by table 32 in [20.1.5]. typedef typename _Alloc::template rebind<_List_node<_Tp> >::other _Node_Alloc_type; struct _List_impl : public _Node_Alloc_type { _List_node_base _M_node; _List_impl (const _Node_Alloc_type& __a) : _Node_Alloc_type(__a) { } }; _List_impl _M_impl; _List_node<_Tp>* _M_get_node() { return _M_impl._Node_Alloc_type::allocate(1); } void _M_put_node(_List_node<_Tp>* __p) { _M_impl._Node_Alloc_type::deallocate(__p, 1); } public: typedef _Alloc allocator_type; allocator_type get_allocator() const { return allocator_type(*static_cast<const _Node_Alloc_type*>(&this->_M_impl)); } _List_base(const allocator_type& __a) : _M_impl(__a) { _M_init(); } // This is what actually destroys the list. ~_List_base() { _M_clear(); } void _M_clear(); void _M_init() { this->_M_impl._M_node._M_next = &this->_M_impl._M_node; this->_M_impl._M_node._M_prev = &this->_M_impl._M_node; } }; /** * @brief A standard container with linear time access to elements, * and fixed time insertion/deletion at any point in the sequence. * * @ingroup Containers * @ingroup Sequences * * Meets the requirements of a <a href="tables.html#65">container</a>, a * <a href="tables.html#66">reversible container</a>, and a * <a href="tables.html#67">sequence</a>, including the * <a href="tables.html#68">optional sequence requirements</a> with the * %exception of @c at and @c operator[]. * * This is a @e doubly @e linked %list. Traversal up and down the * %list requires linear time, but adding and removing elements (or * @e nodes) is done in constant time, regardless of where the * change takes place. Unlike std::vector and std::deque, * random-access iterators are not provided, so subscripting ( @c * [] ) access is not allowed. For algorithms which only need * sequential access, this lack makes no difference. * * Also unlike the other standard containers, std::list provides * specialized algorithms %unique to linked lists, such as * splicing, sorting, and in-place reversal. * * @if maint * A couple points on memory allocation for list<Tp>: * * First, we never actually allocate a Tp, we allocate * List_node<Tp>'s and trust [20.1.5]/4 to DTRT. This is to ensure * that after elements from %list<X,Alloc1> are spliced into * %list<X,Alloc2>, destroying the memory of the second %list is a * valid operation, i.e., Alloc1 giveth and Alloc2 taketh away. * * Second, a %list conceptually represented as * @code * A <---> B <---> C <---> D * @endcode * is actually circular; a link exists between A and D. The %list * class holds (as its only data member) a private list::iterator * pointing to @e D, not to @e A! To get to the head of the %list, * we start at the tail and move forward by one. When this member * iterator's next/previous pointers refer to itself, the %list is * %empty. @endif */ template<typename _Tp, typename _Alloc = allocator<_Tp> > class list : protected _List_base<_Tp, _Alloc> { // concept requirements __glibcxx_class_requires(_Tp, _SGIAssignableConcept) typedef _List_base<_Tp, _Alloc> _Base; public: typedef _Tp value_type; typedef typename _Alloc::pointer pointer; typedef typename _Alloc::const_pointer const_pointer; typedef typename _Alloc::reference reference; typedef typename _Alloc::const_reference const_reference; typedef _List_iterator<_Tp> iterator; typedef _List_const_iterator<_Tp> const_iterator; typedef std::reverse_iterator<const_iterator> const_reverse_iterator; typedef std::reverse_iterator<iterator> reverse_iterator; typedef size_t size_type; typedef ptrdiff_t difference_type; typedef typename _Base::allocator_type allocator_type; protected: // Note that pointers-to-_Node's can be ctor-converted to // iterator types. typedef _List_node<_Tp> _Node; /** @if maint * One data member plus two memory-handling functions. If the * _Alloc type requires separate instances, then one of those * will also be included, accumulated from the topmost parent. * @endif
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