STL源码剖析——单向链表slist

红太狼 2022-08-12 07:58 175阅读 0赞

## 前言 ##

在STL标准中提供了双向链表list，本文介绍的是SGI STL中<stl\_slist.h>定义的单向链表slist。单向链表的迭代器是属于正向迭代器，所以在单链表进行插入元素时，在指定节点之后插入时时间是常数O(1)，在指定节点之前插入时需要线性时间O(n)。单向链表的排序算法sort和list容器的排序算法sort一样的思想，可以再《[STL源码剖析——list容器的排序算法sort()][STL_list_sort]》了解。

## 单向链表slist ##

### slist节点结构 ###

slist的节点结构只有存储节点数据和指向下一个节点的指针。

//单向链表的节点基本结构
    struct _Slist_node_base
    {
      _Slist_node_base* _M_next;
    };
    //单向链表节点结构
    template <class _Tp>
    struct _Slist_node : public _Slist_node_base
    {
      _Tp _M_data;
    };

### slist迭代器 ###

由于slist是单向链表，所以只提供正向迭代器，若要查找指定节点的前一个节点时，operator--不能使用，只能从头遍历，但是可以operator++和operator\*操作；

//单向链表的迭代器的基本结构
    struct _Slist_iterator_base
    {
      typedef size_t               size_type;
      typedef ptrdiff_t            difference_type;
      typedef forward_iterator_tag iterator_category;//正向迭代器
    
      _Slist_node_base* _M_node;//链表节点指针
    
      _Slist_iterator_base(_Slist_node_base* __x) : _M_node(__x) {}
      void _M_incr() { _M_node = _M_node->_M_next; }//前移一个节点
    
      bool operator==(const _Slist_iterator_base& __x) const {
        return _M_node == __x._M_node;//节点指针指向相同位置
      }
      bool operator!=(const _Slist_iterator_base& __x) const {
        return _M_node != __x._M_node;//节点指针指向不同位置
      }
    };
    //单向链表迭代器结构
    template <class _Tp, class _Ref, class _Ptr>
    struct _Slist_iterator : public _Slist_iterator_base
    {
      typedef _Slist_iterator<_Tp, _Tp&, _Tp*>             iterator;
      typedef _Slist_iterator<_Tp, const _Tp&, const _Tp*> const_iterator;
      typedef _Slist_iterator<_Tp, _Ref, _Ptr>             _Self;
    
      typedef _Tp              value_type;
      typedef _Ptr             pointer;
      typedef _Ref             reference;
      typedef _Slist_node<_Tp> _Node;
    
      _Slist_iterator(_Node* __x) : _Slist_iterator_base(__x) {}
      _Slist_iterator() : _Slist_iterator_base(0) {}
      _Slist_iterator(const iterator& __x) : _Slist_iterator_base(__x._M_node) {}
      //解除引用，返回节点数据
      reference operator*() const { return ((_Node*) _M_node)->_M_data; }
    #ifndef __SGI_STL_NO_ARROW_OPERATOR
      pointer operator->() const { return &(operator*()); }
    #endif /* __SGI_STL_NO_ARROW_OPERATOR */
    
      //前缀operator++
      _Self& operator++()
      {
        _M_incr();
        return *this;
      }
      //后缀operator++
      _Self operator++(int)
      {
        _Self __tmp = *this;
        _M_incr();
        return __tmp;
      }
      //单向链表不能operator--操作
    };

### slist的数据结构 ###

slist单向链表只需要给出该链表的头部head，便可以通过head->next遍历该链表；

typedef simple_alloc<_Slist_node<_Tp>, _Alloc> _Alloc_type;
      _Slist_node<_Tp>* _M_get_node() { return _Alloc_type::allocate(1); }
      void _M_put_node(_Slist_node<_Tp>* __p) { _Alloc_type::deallocate(__p, 1); }
    
      _Slist_node_base* _M_erase_after(_Slist_node_base* __pos)
      {
        _Slist_node<_Tp>* __next = (_Slist_node<_Tp>*) (__pos->_M_next);
        _Slist_node_base* __next_next = __next->_M_next;
        __pos->_M_next = __next_next;
        destroy(&__next->_M_data);
        _M_put_node(__next);
        return __next_next;
      }
      _Slist_node_base* _M_erase_after(_Slist_node_base*, _Slist_node_base*);
    
    protected:
      _Slist_node_base _M_head;
    };  
    
    
    //单向链表slist定义
    template <class _Tp, class _Alloc = __STL_DEFAULT_ALLOCATOR(_Tp) >
    class slist : private _Slist_base<_Tp,_Alloc>
    {
      // requirements:
    
      __STL_CLASS_REQUIRES(_Tp, _Assignable);
    
    private:
      typedef _Slist_base<_Tp,_Alloc> _Base;
    public:
      typedef _Tp                value_type;
      typedef value_type*       pointer;
      typedef const value_type* const_pointer;
      typedef value_type&       reference;
      typedef const value_type& const_reference;
      typedef size_t            size_type;
      typedef ptrdiff_t         difference_type;
    
      typedef _Slist_iterator<_Tp, _Tp&, _Tp*>             iterator;
      typedef _Slist_iterator<_Tp, const _Tp&, const _Tp*> const_iterator;
    
    
    private:
      typedef _Slist_node<_Tp>      _Node;
      typedef _Slist_node_base      _Node_base;
      typedef _Slist_iterator_base  _Iterator_base;
      ...
    };

### slist单向链表的源码完成剖析 ###

#ifndef __SGI_STL_INTERNAL_SLIST_H
    #define __SGI_STL_INTERNAL_SLIST_H
    
    #include <concept_checks.h>
    
    __STL_BEGIN_NAMESPACE 
    
    #if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
    #pragma set woff 1174
    #pragma set woff 1375
    #endif
    
    //单向链表的节点基本结构
    struct _Slist_node_base
    {
      _Slist_node_base* _M_next;
    };
    //单向链表节点结构
    template <class _Tp>
    struct _Slist_node : public _Slist_node_base
    {
      _Tp _M_data;
    };
    
    //在节点prev之后插入节点new
    inline _Slist_node_base*
    __slist_make_link(_Slist_node_base* __prev_node,
                      _Slist_node_base* __new_node)
    {
    //更新节点指针
    	//即新节点new下一节点为当前节点prev的下一个节点
      __new_node->_M_next = __prev_node->_M_next;
      //当前节点的prev的下一个节点为new
      __prev_node->_M_next = __new_node;
      return __new_node;//返回新插入节点的地址
    }
    
    //查找指定节点node的前一个节点
    //由于是单向链表，需从表头head开始查找
    inline _Slist_node_base* 
    __slist_previous(_Slist_node_base* __head,
                     const _Slist_node_base* __node)
    {
      while (__head && __head->_M_next != __node)
        __head = __head->_M_next;//遍历节点，直到遇到所找节点或不存在该节点
      return __head;
    }
    
    inline const _Slist_node_base* 
    __slist_previous(const _Slist_node_base* __head,
                     const _Slist_node_base* __node)
    {
      while (__head && __head->_M_next != __node)
        __head = __head->_M_next;
      return __head;
    }
    
    //将节点(before_first,before_last]插入到指定节点pos之后
    inline void __slist_splice_after(_Slist_node_base* __pos,
                                     _Slist_node_base* __before_first,
                                     _Slist_node_base* __before_last)
    {
      if (__pos != __before_first && __pos != __before_last) {
        _Slist_node_base* __first = __before_first->_M_next;
        _Slist_node_base* __after = __pos->_M_next;
    	//将节点链表(before_first,before_last]从链表中移除
        __before_first->_M_next = __before_last->_M_next;
    	//将(before_first,before_last]插入到指定位置pos之后
        __pos->_M_next = __first;
        __before_last->_M_next = __after;
      }
    }
    
    inline void
    __slist_splice_after(_Slist_node_base* __pos, _Slist_node_base* __head)
    {
      _Slist_node_base* __before_last = __slist_previous(__head, 0);//找出链表的最后一个节点
      if (__before_last != __head) {//链表非空
        _Slist_node_base* __after = __pos->_M_next;
        __pos->_M_next = __head->_M_next;
        __head->_M_next = 0;
        __before_last->_M_next = __after;
      }
    }
    //单向链表反转
    //这里参数node必须为第一个结点即为head->next，不然链表会造成内存泄露
    inline _Slist_node_base* __slist_reverse(_Slist_node_base* __node)
    {
      _Slist_node_base* __result = __node;
      __node = __node->_M_next;
      __result->_M_next = 0;//链表尾部
      while(__node) {//链表非空
        _Slist_node_base* __next = __node->_M_next;
        __node->_M_next = __result;
        __result = __node;
        __node = __next;
      }
      return __result;
    }
    //返回链表大小
    //节点参数node必须为第一个节点即为head->next;
    inline size_t __slist_size(_Slist_node_base* __node)
    {
      size_t __result = 0;
      for ( ; __node != 0; __node = __node->_M_next)//遍历链表节点
        ++__result;
      return __result;
    }
    
    //单向链表的迭代器的基本结构
    struct _Slist_iterator_base
    {
      typedef size_t               size_type;
      typedef ptrdiff_t            difference_type;
      typedef forward_iterator_tag iterator_category;//正向迭代器
    
      _Slist_node_base* _M_node;//链表节点指针
    
      _Slist_iterator_base(_Slist_node_base* __x) : _M_node(__x) {}
      void _M_incr() { _M_node = _M_node->_M_next; }//前移一个节点
    
      bool operator==(const _Slist_iterator_base& __x) const {
        return _M_node == __x._M_node;//节点指针指向相同位置
      }
      bool operator!=(const _Slist_iterator_base& __x) const {
        return _M_node != __x._M_node;//节点指针指向不同位置
      }
    };
    //单向链表迭代器结构
    template <class _Tp, class _Ref, class _Ptr>
    struct _Slist_iterator : public _Slist_iterator_base
    {
      typedef _Slist_iterator<_Tp, _Tp&, _Tp*>             iterator;
      typedef _Slist_iterator<_Tp, const _Tp&, const _Tp*> const_iterator;
      typedef _Slist_iterator<_Tp, _Ref, _Ptr>             _Self;
    
      typedef _Tp              value_type;
      typedef _Ptr             pointer;
      typedef _Ref             reference;
      typedef _Slist_node<_Tp> _Node;
    
      _Slist_iterator(_Node* __x) : _Slist_iterator_base(__x) {}
      _Slist_iterator() : _Slist_iterator_base(0) {}
      _Slist_iterator(const iterator& __x) : _Slist_iterator_base(__x._M_node) {}
      //解除引用，返回节点数据
      reference operator*() const { return ((_Node*) _M_node)->_M_data; }
    #ifndef __SGI_STL_NO_ARROW_OPERATOR
      pointer operator->() const { return &(operator*()); }
    #endif /* __SGI_STL_NO_ARROW_OPERATOR */
    
      //前缀operator++
      _Self& operator++()
      {
        _M_incr();
        return *this;
      }
      //后缀operator++
      _Self operator++(int)
      {
        _Self __tmp = *this;
        _M_incr();
        return __tmp;
      }
      //单向链表不能operator--操作
    };
    
    #ifndef __STL_CLASS_PARTIAL_SPECIALIZATION
    
    inline ptrdiff_t* distance_type(const _Slist_iterator_base&) {
      return 0;
    }
    
    inline forward_iterator_tag iterator_category(const _Slist_iterator_base&) {
      return forward_iterator_tag();
    }
    
    template <class _Tp, class _Ref, class _Ptr> 
    inline _Tp* value_type(const _Slist_iterator<_Tp, _Ref, _Ptr>&) {
      return 0;
    }
    
    #endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */
    
    // Base class that encapsulates details of allocators.  Three cases:
    // an ordinary standard-conforming allocator, a standard-conforming
    // allocator with no non-static data, and an SGI-style allocator.
    // This complexity is necessary only because we're worrying about backward
    // compatibility and because we want to avoid wasting storage on an 
    // allocator instance if it isn't necessary.
    
    #ifdef __STL_USE_STD_ALLOCATORS
    
    // Base for general standard-conforming allocators.
    template <class _Tp, class _Allocator, bool _IsStatic>
    class _Slist_alloc_base {
    public:
      typedef typename _Alloc_traits<_Tp,_Allocator>::allocator_type
              allocator_type;
      allocator_type get_allocator() const { return _M_node_allocator; }
    
      _Slist_alloc_base(const allocator_type& __a) : _M_node_allocator(__a) {}
    
    protected:
    	//分配一个节点空间
      _Slist_node<_Tp>* _M_get_node() 
        { return _M_node_allocator.allocate(1); }
      //释放指定的节点空间
      void _M_put_node(_Slist_node<_Tp>* __p) 
        { _M_node_allocator.deallocate(__p, 1); }
    
    protected:
      typename _Alloc_traits<_Slist_node<_Tp>,_Allocator>::allocator_type
               _M_node_allocator;
      _Slist_node_base _M_head;
    };
    
    // Specialization for instanceless allocators.
    template <class _Tp, class _Allocator>
    class _Slist_alloc_base<_Tp,_Allocator, true> {
    public:
      typedef typename _Alloc_traits<_Tp,_Allocator>::allocator_type
              allocator_type;
      allocator_type get_allocator() const { return allocator_type(); }
    
      _Slist_alloc_base(const allocator_type&) {}
    
    protected:
      typedef typename _Alloc_traits<_Slist_node<_Tp>, _Allocator>::_Alloc_type
              _Alloc_type;
      _Slist_node<_Tp>* _M_get_node() { return _Alloc_type::allocate(1); }
      void _M_put_node(_Slist_node<_Tp>* __p) { _Alloc_type::deallocate(__p, 1); }
    
    protected:
      _Slist_node_base _M_head;//链表头
    };
    
    
    template <class _Tp, class _Alloc>
    struct _Slist_base
      : public _Slist_alloc_base<_Tp, _Alloc,
                                 _Alloc_traits<_Tp, _Alloc>::_S_instanceless>
    {
      typedef _Slist_alloc_base<_Tp, _Alloc,
                                _Alloc_traits<_Tp, _Alloc>::_S_instanceless>
              _Base;
      typedef typename _Base::allocator_type allocator_type;
    
      _Slist_base(const allocator_type& __a)
        : _Base(__a) { this->_M_head._M_next = 0; }
      ~_Slist_base() { _M_erase_after(&this->_M_head, 0); }
    
    protected:
    	//擦除指定节点的后一个节点
      _Slist_node_base* _M_erase_after(_Slist_node_base* __pos)
      {
        _Slist_node<_Tp>* __next = (_Slist_node<_Tp>*) (__pos->_M_next);
        _Slist_node_base* __next_next = __next->_M_next;
        __pos->_M_next = __next_next;
        destroy(&__next->_M_data);
        _M_put_node(__next);
        return __next_next;
      }
      _Slist_node_base* _M_erase_after(_Slist_node_base*, _Slist_node_base*);
    };
    
    #else /* __STL_USE_STD_ALLOCATORS */
    
    template <class _Tp, class _Alloc> 
    struct _Slist_base {
      typedef _Alloc allocator_type;
      allocator_type get_allocator() const { return allocator_type(); }
    
      _Slist_base(const allocator_type&) { _M_head._M_next = 0; }
      ~_Slist_base() { _M_erase_after(&_M_head, 0); }
    
    protected:
      typedef simple_alloc<_Slist_node<_Tp>, _Alloc> _Alloc_type;
      _Slist_node<_Tp>* _M_get_node() { return _Alloc_type::allocate(1); }
      void _M_put_node(_Slist_node<_Tp>* __p) { _Alloc_type::deallocate(__p, 1); }
    
      _Slist_node_base* _M_erase_after(_Slist_node_base* __pos)
      {
        _Slist_node<_Tp>* __next = (_Slist_node<_Tp>*) (__pos->_M_next);
        _Slist_node_base* __next_next = __next->_M_next;
        __pos->_M_next = __next_next;
        destroy(&__next->_M_data);
        _M_put_node(__next);
        return __next_next;
      }
      _Slist_node_base* _M_erase_after(_Slist_node_base*, _Slist_node_base*);
    
    protected:
      _Slist_node_base _M_head;
    };  
    
    #endif /* __STL_USE_STD_ALLOCATORS */
    
    //擦除(first,last)之间的节点
    template <class _Tp, class _Alloc> 
    _Slist_node_base*
    _Slist_base<_Tp,_Alloc>::_M_erase_after(_Slist_node_base* __before_first,
                                            _Slist_node_base* __last_node) {
      _Slist_node<_Tp>* __cur = (_Slist_node<_Tp>*) (__before_first->_M_next);
      while (__cur != __last_node) {
        _Slist_node<_Tp>* __tmp = __cur;
        __cur = (_Slist_node<_Tp>*) __cur->_M_next;
        destroy(&__tmp->_M_data);
        _M_put_node(__tmp);
      }
      __before_first->_M_next = __last_node;
      return __last_node;
    }
    
    //单向链表slist定义
    template <class _Tp, class _Alloc = __STL_DEFAULT_ALLOCATOR(_Tp) >
    class slist : private _Slist_base<_Tp,_Alloc>
    {
      // requirements:
    
      __STL_CLASS_REQUIRES(_Tp, _Assignable);
    
    private:
      typedef _Slist_base<_Tp,_Alloc> _Base;
    public:
      typedef _Tp                value_type;
      typedef value_type*       pointer;
      typedef const value_type* const_pointer;
      typedef value_type&       reference;
      typedef const value_type& const_reference;
      typedef size_t            size_type;
      typedef ptrdiff_t         difference_type;
    
      typedef _Slist_iterator<_Tp, _Tp&, _Tp*>             iterator;
      typedef _Slist_iterator<_Tp, const _Tp&, const _Tp*> const_iterator;
    
      typedef typename _Base::allocator_type allocator_type;
      allocator_type get_allocator() const { return _Base::get_allocator(); }
    
    private:
      typedef _Slist_node<_Tp>      _Node;
      typedef _Slist_node_base      _Node_base;
      typedef _Slist_iterator_base  _Iterator_base;
    
      //创建初始值为x的节点
      _Node* _M_create_node(const value_type& __x) {
        _Node* __node = this->_M_get_node();
        __STL_TRY {
          construct(&__node->_M_data, __x);
          __node->_M_next = 0;
        }
        __STL_UNWIND(this->_M_put_node(__node));
        return __node;
      }
      
      _Node* _M_create_node() {
        _Node* __node = this->_M_get_node();
        __STL_TRY {
          construct(&__node->_M_data);
          __node->_M_next = 0;
        }
        __STL_UNWIND(this->_M_put_node(__node));
        return __node;
      }
    
    public:
      explicit slist(const allocator_type& __a = allocator_type()) : _Base(__a) {}
    
      slist(size_type __n, const value_type& __x,
            const allocator_type& __a =  allocator_type()) : _Base(__a)
        { _M_insert_after_fill(&this->_M_head, __n, __x); }
    
      explicit slist(size_type __n) : _Base(allocator_type())
        { _M_insert_after_fill(&this->_M_head, __n, value_type()); }
    
    #ifdef __STL_MEMBER_TEMPLATES
      // We don't need any dispatching tricks here, because _M_insert_after_range
      // already does them.
      template <class _InputIterator>
      slist(_InputIterator __first, _InputIterator __last,
            const allocator_type& __a =  allocator_type()) : _Base(__a)
        { _M_insert_after_range(&this->_M_head, __first, __last); }
    
    #else /* __STL_MEMBER_TEMPLATES */
      slist(const_iterator __first, const_iterator __last,
            const allocator_type& __a =  allocator_type()) : _Base(__a)
        { _M_insert_after_range(&this->_M_head, __first, __last); }
      slist(const value_type* __first, const value_type* __last,
            const allocator_type& __a =  allocator_type()) : _Base(__a)
        { _M_insert_after_range(&this->_M_head, __first, __last); }
    #endif /* __STL_MEMBER_TEMPLATES */
    
      slist(const slist& __x) : _Base(__x.get_allocator())
        { _M_insert_after_range(&this->_M_head, __x.begin(), __x.end()); }
    
      slist& operator= (const slist& __x);
    
      ~slist() {}
    
    public:
      // assign(), a generalized assignment member function.  Two
      // versions: one that takes a count, and one that takes a range.
      // The range version is a member template, so we dispatch on whether
      // or not the type is an integer.
    
      void assign(size_type __n, const _Tp& __val)
        { _M_fill_assign(__n, __val); }
    
      void _M_fill_assign(size_type __n, const _Tp& __val);
    
    
    #ifdef __STL_MEMBER_TEMPLATES
    
      template <class _InputIterator>
      void assign(_InputIterator __first, _InputIterator __last) {
        typedef typename _Is_integer<_InputIterator>::_Integral _Integral;
        _M_assign_dispatch(__first, __last, _Integral());
      }
    
      template <class _Integer>
      void _M_assign_dispatch(_Integer __n, _Integer __val, __true_type)
        { _M_fill_assign((size_type) __n, (_Tp) __val); }
    
      template <class _InputIterator>
      void _M_assign_dispatch(_InputIterator __first, _InputIterator __last,
                              __false_type);
    
    #endif /* __STL_MEMBER_TEMPLATES */
    
    public:
    
      //返回第一个节点迭代器
    	iterator begin() { return iterator((_Node*)this->_M_head._M_next); }
      const_iterator begin() const 
        { return const_iterator((_Node*)this->_M_head._M_next);}
    
      //返回链表尾部
      iterator end() { return iterator(0); }
      const_iterator end() const { return const_iterator(0); }
    
      // Experimental new feature: before_begin() returns a
      // non-dereferenceable iterator that, when incremented, yields
      // begin().  This iterator may be used as the argument to
      // insert_after, erase_after, etc.  Note that even for an empty 
      // slist, before_begin() is not the same iterator as end().  It 
      // is always necessary to increment before_begin() at least once to
      // obtain end().
      //链表头
      iterator before_begin() { return iterator((_Node*) &this->_M_head); }
      const_iterator before_begin() const
        { return const_iterator((_Node*) &this->_M_head); }
    
      //返回链表大小
      size_type size() const { return __slist_size(this->_M_head._M_next); }
      
      size_type max_size() const { return size_type(-1); }
    
      //判断是否为空链表
      bool empty() const { return this->_M_head._M_next == 0; }
    
      //交换链表内容
      //实质上只交换指向链表的指针
      void swap(slist& __x)
        { __STD::swap(this->_M_head._M_next, __x._M_head._M_next); }
    
    public:
    
      //返回第一个节点数据
    	reference front() { return ((_Node*) this->_M_head._M_next)->_M_data; }
      const_reference front() const 
        { return ((_Node*) this->_M_head._M_next)->_M_data; }
      //在链表头部新增节点
      void push_front(const value_type& __x)   {
        __slist_make_link(&this->_M_head, _M_create_node(__x));
      }
      void push_front() { __slist_make_link(&this->_M_head, _M_create_node()); }
     //删除节点
      void pop_front() {
        _Node* __node = (_Node*) this->_M_head._M_next;
        this->_M_head._M_next = __node->_M_next;
        destroy(&__node->_M_data);
        this->_M_put_node(__node);
      }
    
      //返回指定节点的前一个节点
      iterator previous(const_iterator __pos) {
        return iterator((_Node*) __slist_previous(&this->_M_head, __pos._M_node));
      }
      const_iterator previous(const_iterator __pos) const {
        return const_iterator((_Node*) __slist_previous(&this->_M_head,
                                                        __pos._M_node));
      }
    
    private:
    	//在指定节点后面插入值为x的节点
      _Node* _M_insert_after(_Node_base* __pos, const value_type& __x) {
        return (_Node*) (__slist_make_link(__pos, _M_create_node(__x)));
      }
    
      _Node* _M_insert_after(_Node_base* __pos) {
        return (_Node*) (__slist_make_link(__pos, _M_create_node()));
      }
    
      //在指定节点后面连续插入n个值为x的节点
      void _M_insert_after_fill(_Node_base* __pos,
                                size_type __n, const value_type& __x) {
        for (size_type __i = 0; __i < __n; ++__i)
          __pos = __slist_make_link(__pos, _M_create_node(__x));
      }
    
    #ifdef __STL_MEMBER_TEMPLATES
    
      // Check whether it's an integral type.  If so, it's not an iterator.
      //在指定节点之后插入[first,last)数据节点
      //首先判断输入数据类型是否为整数
      template <class _InIter>
      void _M_insert_after_range(_Node_base* __pos, 
                                 _InIter __first, _InIter __last) {
        typedef typename _Is_integer<_InIter>::_Integral _Integral;
        _M_insert_after_range(__pos, __first, __last, _Integral());
      }
    
      //若是整数，则在指定节点之后连续插入n个相同节点
      template <class _Integer>
      void _M_insert_after_range(_Node_base* __pos, _Integer __n, _Integer __x,
                                 __true_type) {
        _M_insert_after_fill(__pos, __n, __x);
      }
    
      //若不是整数，则一个一个节点一次插入
      template <class _InIter>
      void _M_insert_after_range(_Node_base* __pos,
                                 _InIter __first, _InIter __last,
                                 __false_type) {
        while (__first != __last) {
          __pos = __slist_make_link(__pos, _M_create_node(*__first));
          ++__first;
        }
      }
    
    #else /* __STL_MEMBER_TEMPLATES */
    
      void _M_insert_after_range(_Node_base* __pos,
                                 const_iterator __first, const_iterator __last) {
        while (__first != __last) {
          __pos = __slist_make_link(__pos, _M_create_node(*__first));
          ++__first;
        }
      }
      void _M_insert_after_range(_Node_base* __pos,
                                 const value_type* __first,
                                 const value_type* __last) {
        while (__first != __last) {
          __pos = __slist_make_link(__pos, _M_create_node(*__first));
          ++__first;
        }
      }
    
    #endif /* __STL_MEMBER_TEMPLATES */
    
    public:
    	//对外接口
      iterator insert_after(iterator __pos, const value_type& __x) {
        return iterator(_M_insert_after(__pos._M_node, __x));
      }
    
      iterator insert_after(iterator __pos) {
        return insert_after(__pos, value_type());
      }
    
      void insert_after(iterator __pos, size_type __n, const value_type& __x) {
        _M_insert_after_fill(__pos._M_node, __n, __x);
      }
    
    #ifdef __STL_MEMBER_TEMPLATES
    
      // We don't need any dispatching tricks here, because _M_insert_after_range
      // already does them.
      template <class _InIter>
      void insert_after(iterator __pos, _InIter __first, _InIter __last) {
        _M_insert_after_range(__pos._M_node, __first, __last);
      }
    
    #else /* __STL_MEMBER_TEMPLATES */
    
      void insert_after(iterator __pos,
                        const_iterator __first, const_iterator __last) {
        _M_insert_after_range(__pos._M_node, __first, __last);
      }
      void insert_after(iterator __pos,
                        const value_type* __first, const value_type* __last) {
        _M_insert_after_range(__pos._M_node, __first, __last);
      }
    
    #endif /* __STL_MEMBER_TEMPLATES */
    	//在指定节点之前插入
      iterator insert(iterator __pos, const value_type& __x) {
    	  //这里首先找出指定节点的前一个节点，然后再把新节点插入到前一节点的后面
        return iterator(_M_insert_after(__slist_previous(&this->_M_head,
                                                         __pos._M_node),
                        __x));
      }
    
      iterator insert(iterator __pos) {
        return iterator(_M_insert_after(__slist_previous(&this->_M_head,
                                                         __pos._M_node),
                                        value_type()));
      }
    
      void insert(iterator __pos, size_type __n, const value_type& __x) {
        _M_insert_after_fill(__slist_previous(&this->_M_head, __pos._M_node),
                             __n, __x);
      } 
        
    #ifdef __STL_MEMBER_TEMPLATES
    
      // We don't need any dispatching tricks here, because _M_insert_after_range
      // already does them.
      template <class _InIter>
      void insert(iterator __pos, _InIter __first, _InIter __last) {
        _M_insert_after_range(__slist_previous(&this->_M_head, __pos._M_node), 
                              __first, __last);
      }
    
    #else /* __STL_MEMBER_TEMPLATES */
    
      void insert(iterator __pos, const_iterator __first, const_iterator __last) {
        _M_insert_after_range(__slist_previous(&this->_M_head, __pos._M_node), 
                              __first, __last);
      }
      void insert(iterator __pos, const value_type* __first, 
                                  const value_type* __last) {
        _M_insert_after_range(__slist_previous(&this->_M_head, __pos._M_node), 
                              __first, __last);
      }
    
    #endif /* __STL_MEMBER_TEMPLATES */
    
    
    public:
    	//在指定节点之后擦除节点
      iterator erase_after(iterator __pos) {
        return iterator((_Node*) this->_M_erase_after(__pos._M_node));
      }
      iterator erase_after(iterator __before_first, iterator __last) {
        return iterator((_Node*) this->_M_erase_after(__before_first._M_node, 
                                                      __last._M_node));
      } 
    
      iterator erase(iterator __pos) {
        return (_Node*) this->_M_erase_after(__slist_previous(&this->_M_head, 
                                                              __pos._M_node));
      }
      iterator erase(iterator __first, iterator __last) {
        return (_Node*) this->_M_erase_after(
          __slist_previous(&this->_M_head, __first._M_node), __last._M_node);
      }
    
      //从新分配单向链表大小
      void resize(size_type new_size, const _Tp& __x);
      void resize(size_type new_size) { resize(new_size, _Tp()); }
      //清除链表
      void clear() { this->_M_erase_after(&this->_M_head, 0); }
    
    public:
      // Moves the range [__before_first + 1, __before_last + 1) to *this,
      //  inserting it immediately after __pos.  This is constant time.
      void splice_after(iterator __pos, 
                        iterator __before_first, iterator __before_last)
      {
        if (__before_first != __before_last) 
          __slist_splice_after(__pos._M_node, __before_first._M_node, 
                               __before_last._M_node);
      }
    
      // Moves the element that follows __prev to *this, inserting it immediately
      //  after __pos.  This is constant time.
      void splice_after(iterator __pos, iterator __prev)
      {
        __slist_splice_after(__pos._M_node,
                             __prev._M_node, __prev._M_node->_M_next);
      }
    
    
      // Removes all of the elements from the list __x to *this, inserting
      // them immediately after __pos.  __x must not be *this.  Complexity:
      // linear in __x.size().
      void splice_after(iterator __pos, slist& __x)
      {
        __slist_splice_after(__pos._M_node, &__x._M_head);
      }
    
      // Linear in distance(begin(), __pos), and linear in __x.size().
      void splice(iterator __pos, slist& __x) {
        if (__x._M_head._M_next)
          __slist_splice_after(__slist_previous(&this->_M_head, __pos._M_node),
                               &__x._M_head, __slist_previous(&__x._M_head, 0));
      }
    
      // Linear in distance(begin(), __pos), and in distance(__x.begin(), __i).
      void splice(iterator __pos, slist& __x, iterator __i) {
        __slist_splice_after(__slist_previous(&this->_M_head, __pos._M_node),
                             __slist_previous(&__x._M_head, __i._M_node),
                             __i._M_node);
      }
    
      // Linear in distance(begin(), __pos), in distance(__x.begin(), __first),
      // and in distance(__first, __last).
      void splice(iterator __pos, slist& __x, iterator __first, iterator __last)
      {
        if (__first != __last)
          __slist_splice_after(__slist_previous(&this->_M_head, __pos._M_node),
                               __slist_previous(&__x._M_head, __first._M_node),
                               __slist_previous(__first._M_node, __last._M_node));
      }
    
    public:
      void reverse() { 
        if (this->_M_head._M_next)
          this->_M_head._M_next = __slist_reverse(this->_M_head._M_next);
      }
    
      void remove(const _Tp& __val); 
      void unique(); 
      void merge(slist& __x);
      void sort();     
    
    #ifdef __STL_MEMBER_TEMPLATES
      template <class _Predicate> 
      void remove_if(_Predicate __pred);
    
      template <class _BinaryPredicate> 
      void unique(_BinaryPredicate __pred); 
    
      template <class _StrictWeakOrdering> 
      void merge(slist&, _StrictWeakOrdering);
    
      template <class _StrictWeakOrdering> 
      void sort(_StrictWeakOrdering __comp); 
    #endif /* __STL_MEMBER_TEMPLATES */
    };
    
    //实现整个单向链表的赋值
    template <class _Tp, class _Alloc>
    slist<_Tp,_Alloc>& slist<_Tp,_Alloc>::operator=(const slist<_Tp,_Alloc>& __x)
    {
      if (&__x != this) {
        _Node_base* __p1 = &this->_M_head;
        _Node* __n1 = (_Node*) this->_M_head._M_next;
        const _Node* __n2 = (const _Node*) __x._M_head._M_next;
        while (__n1 && __n2) {
          __n1->_M_data = __n2->_M_data;
          __p1 = __n1;
          __n1 = (_Node*) __n1->_M_next;
          __n2 = (const _Node*) __n2->_M_next;
        }
        if (__n2 == 0)//擦除多余的节点
          this->_M_erase_after(__p1, 0);
        else//插入剩下的节点
          _M_insert_after_range(__p1, const_iterator((_Node*)__n2), 
                                      const_iterator(0));
      }
      return *this;
    }
    
    template <class _Tp, class _Alloc>
    void slist<_Tp, _Alloc>::_M_fill_assign(size_type __n, const _Tp& __val) {
      _Node_base* __prev = &this->_M_head;
      _Node* __node = (_Node*) this->_M_head._M_next;
      for ( ; __node != 0 && __n > 0 ; --__n) {
        __node->_M_data = __val;
        __prev = __node;
        __node = (_Node*) __node->_M_next;
      }
      if (__n > 0)
        _M_insert_after_fill(__prev, __n, __val);
      else
        this->_M_erase_after(__prev, 0);
    }
    
    #ifdef __STL_MEMBER_TEMPLATES
    
    template <class _Tp, class _Alloc> template <class _InputIter>
    void
    slist<_Tp, _Alloc>::_M_assign_dispatch(_InputIter __first, _InputIter __last,
                                           __false_type)
    {
      _Node_base* __prev = &this->_M_head;
      _Node* __node = (_Node*) this->_M_head._M_next;
      while (__node != 0 && __first != __last) {
        __node->_M_data = *__first;
        __prev = __node;
        __node = (_Node*) __node->_M_next;
        ++__first;
      }
      if (__first != __last)
        _M_insert_after_range(__prev, __first, __last);
      else
        this->_M_erase_after(__prev, 0);
    }
    
    #endif /* __STL_MEMBER_TEMPLATES */
    
    template <class _Tp, class _Alloc>
    inline bool 
    operator==(const slist<_Tp,_Alloc>& _SL1, const slist<_Tp,_Alloc>& _SL2)
    {
      typedef typename slist<_Tp,_Alloc>::const_iterator const_iterator;
      const_iterator __end1 = _SL1.end();
      const_iterator __end2 = _SL2.end();
    
      const_iterator __i1 = _SL1.begin();
      const_iterator __i2 = _SL2.begin();
      while (__i1 != __end1 && __i2 != __end2 && *__i1 == *__i2) {
        ++__i1;
        ++__i2;
      }
      return __i1 == __end1 && __i2 == __end2;
    }
    
    
    template <class _Tp, class _Alloc>
    inline bool
    operator<(const slist<_Tp,_Alloc>& _SL1, const slist<_Tp,_Alloc>& _SL2)
    {
      return lexicographical_compare(_SL1.begin(), _SL1.end(), 
                                     _SL2.begin(), _SL2.end());
    }
    
    #ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER
    
    template <class _Tp, class _Alloc>
    inline bool 
    operator!=(const slist<_Tp,_Alloc>& _SL1, const slist<_Tp,_Alloc>& _SL2) {
      return !(_SL1 == _SL2);
    }
    
    template <class _Tp, class _Alloc>
    inline bool 
    operator>(const slist<_Tp,_Alloc>& _SL1, const slist<_Tp,_Alloc>& _SL2) {
      return _SL2 < _SL1;
    }
    
    template <class _Tp, class _Alloc>
    inline bool 
    operator<=(const slist<_Tp,_Alloc>& _SL1, const slist<_Tp,_Alloc>& _SL2) {
      return !(_SL2 < _SL1);
    }
    
    template <class _Tp, class _Alloc>
    inline bool 
    operator>=(const slist<_Tp,_Alloc>& _SL1, const slist<_Tp,_Alloc>& _SL2) {
      return !(_SL1 < _SL2);
    }
    
    template <class _Tp, class _Alloc>
    inline void swap(slist<_Tp,_Alloc>& __x, slist<_Tp,_Alloc>& __y) {
      __x.swap(__y);
    }
    
    #endif /* __STL_FUNCTION_TMPL_PARTIAL_ORDER */
    
    
    template <class _Tp, class _Alloc>
    void slist<_Tp,_Alloc>::resize(size_type __len, const _Tp& __x)
    {
      _Node_base* __cur = &this->_M_head;
      while (__cur->_M_next != 0 && __len > 0) {
        --__len;
        __cur = __cur->_M_next;
      }
      if (__cur->_M_next) //若新的大小比原来的小
        this->_M_erase_after(__cur, 0);
      else//若新的大小比原来的大
        _M_insert_after_fill(__cur, __len, __x);
    }
    
    //删除所有值为val的节点
    template <class _Tp, class _Alloc>
    void slist<_Tp,_Alloc>::remove(const _Tp& __val)
    {
      _Node_base* __cur = &this->_M_head;
      while (__cur && __cur->_M_next) {
        if (((_Node*) __cur->_M_next)->_M_data == __val)
          this->_M_erase_after(__cur);
        else
          __cur = __cur->_M_next;
      }
    }
    
    
    //删除连续相同值的节点，使其唯一
    template <class _Tp, class _Alloc> 
    void slist<_Tp,_Alloc>::unique()
    {
      _Node_base* __cur = this->_M_head._M_next;
      if (__cur) {
        while (__cur->_M_next) {
          if (((_Node*)__cur)->_M_data == 
              ((_Node*)(__cur->_M_next))->_M_data)
            this->_M_erase_after(__cur);
          else
            __cur = __cur->_M_next;
        }
      }
    }
    
    //合并两个有序单链表
    template <class _Tp, class _Alloc>
    void slist<_Tp,_Alloc>::merge(slist<_Tp,_Alloc>& __x)
    {
      _Node_base* __n1 = &this->_M_head;
      while (__n1->_M_next && __x._M_head._M_next) {
        if (((_Node*) __x._M_head._M_next)->_M_data < 
            ((_Node*)       __n1->_M_next)->_M_data) 
          __slist_splice_after(__n1, &__x._M_head, __x._M_head._M_next);
        __n1 = __n1->_M_next;
      }
      if (__x._M_head._M_next) {
        __n1->_M_next = __x._M_head._M_next;
        __x._M_head._M_next = 0;
      }
    }
    
    //这里的排序算法跟list的相似
    template <class _Tp, class _Alloc>
    void slist<_Tp,_Alloc>::sort()
    {
      if (this->_M_head._M_next && this->_M_head._M_next->_M_next) {
        slist __carry;
        slist __counter[64];
        int __fill = 0;
        while (!empty()) {
          __slist_splice_after(&__carry._M_head,
                               &this->_M_head, this->_M_head._M_next);
          int __i = 0;
          while (__i < __fill && !__counter[__i].empty()) {
            __counter[__i].merge(__carry);
            __carry.swap(__counter[__i]);
            ++__i;
          }
          __carry.swap(__counter[__i]);
          if (__i == __fill)
            ++__fill;
        }
    
        for (int __i = 1; __i < __fill; ++__i)
          __counter[__i].merge(__counter[__i-1]);
        this->swap(__counter[__fill-1]);
      }
    }
    
    #ifdef __STL_MEMBER_TEMPLATES
    
    template <class _Tp, class _Alloc> 
    template <class _Predicate>
    void slist<_Tp,_Alloc>::remove_if(_Predicate __pred)
    {
      _Node_base* __cur = &this->_M_head;
      while (__cur->_M_next) {
        if (__pred(((_Node*) __cur->_M_next)->_M_data))
          this->_M_erase_after(__cur);
        else
          __cur = __cur->_M_next;
      }
    }
    
    template <class _Tp, class _Alloc> template <class _BinaryPredicate> 
    void slist<_Tp,_Alloc>::unique(_BinaryPredicate __pred)
    {
      _Node* __cur = (_Node*) this->_M_head._M_next;
      if (__cur) {
        while (__cur->_M_next) {
          if (__pred(((_Node*)__cur)->_M_data, 
                     ((_Node*)(__cur->_M_next))->_M_data))
            this->_M_erase_after(__cur);
          else
            __cur = (_Node*) __cur->_M_next;
        }
      }
    }
    
    template <class _Tp, class _Alloc> template <class _StrictWeakOrdering>
    void slist<_Tp,_Alloc>::merge(slist<_Tp,_Alloc>& __x,
                                  _StrictWeakOrdering __comp)
    {
      _Node_base* __n1 = &this->_M_head;
      while (__n1->_M_next && __x._M_head._M_next) {
        if (__comp(((_Node*) __x._M_head._M_next)->_M_data,
                   ((_Node*)       __n1->_M_next)->_M_data))
          __slist_splice_after(__n1, &__x._M_head, __x._M_head._M_next);
        __n1 = __n1->_M_next;
      }
      if (__x._M_head._M_next) {
        __n1->_M_next = __x._M_head._M_next;
        __x._M_head._M_next = 0;
      }
    }
    
    template <class _Tp, class _Alloc> template <class _StrictWeakOrdering> 
    void slist<_Tp,_Alloc>::sort(_StrictWeakOrdering __comp)
    {
      if (this->_M_head._M_next && this->_M_head._M_next->_M_next) {
        slist __carry;
        slist __counter[64];
        int __fill = 0;
        while (!empty()) {
          __slist_splice_after(&__carry._M_head,
                               &this->_M_head, this->_M_head._M_next);
          int __i = 0;
          while (__i < __fill && !__counter[__i].empty()) {
            __counter[__i].merge(__carry, __comp);
            __carry.swap(__counter[__i]);
            ++__i;
          }
          __carry.swap(__counter[__i]);
          if (__i == __fill)
            ++__fill;
        }
    
        for (int __i = 1; __i < __fill; ++__i)
          __counter[__i].merge(__counter[__i-1], __comp);
        this->swap(__counter[__fill-1]);
      }
    }
    
    #endif /* __STL_MEMBER_TEMPLATES */
    
    // Specialization of insert_iterator so that insertions will be constant
    // time rather than linear time.
    
    #ifdef __STL_CLASS_PARTIAL_SPECIALIZATION
    
    template <class _Tp, class _Alloc>
    class insert_iterator<slist<_Tp, _Alloc> > {
    protected:
      typedef slist<_Tp, _Alloc> _Container;
      _Container* container;
      typename _Container::iterator iter;
    public:
      typedef _Container          container_type;
      typedef output_iterator_tag iterator_category;
      typedef void                value_type;
      typedef void                difference_type;
      typedef void                pointer;
      typedef void                reference;
    
      insert_iterator(_Container& __x, typename _Container::iterator __i) 
        : container(&__x) {
        if (__i == __x.begin())
          iter = __x.before_begin();
        else
          iter = __x.previous(__i);
      }
    
      insert_iterator<_Container>&
      operator=(const typename _Container::value_type& __value) { 
        iter = container->insert_after(iter, __value);
        return *this;
      }
      insert_iterator<_Container>& operator*() { return *this; }
      insert_iterator<_Container>& operator++() { return *this; }
      insert_iterator<_Container>& operator++(int) { return *this; }
    };
    
    #endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */
    
    #if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
    #pragma reset woff 1174
    #pragma reset woff 1375
    #endif
    
    __STL_END_NAMESPACE 
    
    #endif /* __SGI_STL_INTERNAL_SLIST_H */
    
    // Local Variables:
    // mode:C++
    // End:

参考资料：

《STL源码剖析》侯捷

[《STL源码剖析---stl\_slist.h阅读笔记》][STL_---stl_slist.h]

[《STL源码剖析-- stl\_slist.h》][STL_-- stl_slist.h]

[STL_list_sort]: http://blog.csdn.net/chenhanzhun/article/details/39337331
[STL_---stl_slist.h]: http://blog.csdn.net/kangroger/article/details/38561817
[STL_-- stl_slist.h]: http://blog.csdn.net/mdl13412/article/details/6648134