stl_list.h

/*
 *
 * 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.
 */

/* NOTE: This is an internal header file, included by other STL headers.
 *   You should not attempt to use it directly.
 */

#ifndef __SGI_STL_INTERNAL_LIST_H
#define __SGI_STL_INTERNAL_LIST_H

__STL_BEGIN_NAMESPACE

#if defined(__sgi) && !defined(__GNUC__) && (_MIPS_SIM != _MIPS_SIM_ABI32)
#pragma set woff 1174
#pragma set woff 1375
#endif

//结点类型的定义
template <class _Tp>
struct _List_node {
  typedef void* _Void_pointer;
  _Void_pointer _M_next;
  _Void_pointer _M_prev;
  _Tp _M_data;
};

//迭代器的设计，封装了一个_List_node类型的指针
//包括的内容有：迭代器的相关属性，构造函数，操作符重载（相等，不等，箭头操作符，解引用操作符，前置和后置的加加减减）；
//本质上就是一个智能指针
template<class _Tp, class _Ref, class _Ptr>
struct _List_iterator {
  typedef _List_iterator<_Tp,_Tp&,_Tp*>             iterator;
  typedef _List_iterator<_Tp,const _Tp&,const _Tp*> const_iterator;
  typedef _List_iterator<_Tp,_Ref,_Ptr>             _Self;

  typedef bidirectional_iterator_tag iterator_category;
  typedef _Tp value_type;
  typedef _Ptr pointer;
  typedef _Ref reference;
  typedef _List_node<_Tp> _Node;
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;

  _Node* _M_node;

  _List_iterator(_Node* __x) : _M_node(__x) {}
  _List_iterator() {}
  _List_iterator(const iterator& __x) : _M_node(__x._M_node) {}

  bool operator==(const _Self& __x) const { return _M_node == __x._M_node; }
  bool operator!=(const _Self& __x) const { return _M_node != __x._M_node; }
  reference operator*() const { return (*_M_node)._M_data; }

#ifndef __SGI_STL_NO_ARROW_OPERATOR
  pointer operator->() const { return &(operator*()); }
#endif /* __SGI_STL_NO_ARROW_OPERATOR */

  _Self& operator++() { 
    _M_node = (_Node*)(_M_node->_M_next);
    return *this;
  }
  _Self operator++(int) { 
    _Self __tmp = *this;
    ++*this;
    return __tmp;
  }
  _Self& operator--() { 
    _M_node = (_Node*)(_M_node->_M_prev);
    return *this;
  }
  _Self operator--(int) { 
    _Self __tmp = *this;
    --*this;
    return __tmp;
  }
};

#ifndef __STL_CLASS_PARTIAL_SPECIALIZATION

//方便地返回迭代器的类型
template <class _Tp, class _Ref, class _Ptr>
inline bidirectional_iterator_tag
iterator_category(const _List_iterator<_Tp, _Ref, _Ptr>&)
{
  return bidirectional_iterator_tag();
}
//方便地返回值类型
template <class _Tp, class _Ref, class _Ptr>
inline _Tp*
value_type(const _List_iterator<_Tp, _Ref, _Ptr>&)
{
  return 0;
}
//方便地返回距离类型
template <class _Tp, class _Ref, class _Ptr>
inline ptrdiff_t*
distance_type(const _List_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.


//通过增加一个空的节点，很好地实现了左闭右开的统一规范
#ifdef __STL_USE_STD_ALLOCATORS

// Base for general standard-conforming allocators.
template <class _Tp, class _Allocator, bool _IsStatic>
class _List_alloc_base {
public:
//泛型的分配器类型
  typedef typename _Alloc_traits<_Tp, _Allocator>::allocator_type
          allocator_type;
  allocator_type get_allocator() const { return _Node_allocator; }

  _List_alloc_base(const allocator_type& __a) : _Node_allocator(__a) {}

protected:
//分配节点和释放节点的操作
  _List_node<_Tp>* _M_get_node()
   { return _Node_allocator.allocate(1); }
  void _M_put_node(_List_node<_Tp>* __p)
    { _Node_allocator.deallocate(__p, 1); }

protected:
//以_list_node为单位的分配器
  typename _Alloc_traits<_List_node<_Tp>, _Allocator>::allocator_type
           _Node_allocator;
  _List_node<_Tp>* _M_node;
};

// Specialization for instanceless allocators.

template <class _Tp, class _Allocator>
class _List_alloc_base<_Tp, _Allocator, true> {
public:
  typedef typename _Alloc_traits<_Tp, _Allocator>::allocator_type
          allocator_type;
  allocator_type get_allocator() const { return allocator_type(); }

  _List_alloc_base(const allocator_type&) {}

protected:
  typedef typename _Alloc_traits<_List_node<_Tp>, _Allocator>::_Alloc_type
          _Alloc_type;
  _List_node<_Tp>* _M_get_node() { return _Alloc_type::allocate(1); }
  void _M_put_node(_List_node<_Tp>* __p) { _Alloc_type::deallocate(__p, 1); }

protected:
  _List_node<_Tp>* _M_node;
};

template <class _Tp, class _Alloc>
//根据需求选择合适的分配器类型
class _List_base 
  : public _List_alloc_base<_Tp, _Alloc,
                            _Alloc_traits<_Tp, _Alloc>::_S_instanceless>
{
public:
  typedef _List_alloc_base<_Tp, _Alloc,
                           _Alloc_traits<_Tp, _Alloc>::_S_instanceless>
          _Base; 
  typedef typename _Base::allocator_type allocator_type;

  _List_base(const allocator_type& __a) : _Base(__a) {
    _M_node = _M_get_node();
    _M_node->_M_next = _M_node;
    _M_node->_M_prev = _M_node;
  }
  ~_List_base() {
    clear();
    _M_put_node(_M_node);
  }

  void clear();
};

#else /* __STL_USE_STD_ALLOCATORS */
//封装空间配置器的使用，提供类型化空间配置的接口;
template <class _Tp, class _Alloc>
class _List_base 
{
public:
  typedef _Alloc allocator_type;
  allocator_type get_allocator() const { return allocator_type(); }

  _List_base(const allocator_type&) {
    _M_node = _M_get_node();
    _M_node->_M_next = _M_node;
    _M_node->_M_prev = _M_node;
  }
  ~_List_base() {
    clear();
    _M_put_node(_M_node);
  }

  void clear();

protected:
  typedef simple_alloc<_List_node<_Tp>, _Alloc> _Alloc_type;
  _List_node<_Tp>* _M_get_node() { return _Alloc_type::allocate(1); }
  void _M_put_node(_List_node<_Tp>* __p) { _Alloc_type::deallocate(__p, 1); } 

protected:
  _List_node<_Tp>* _M_node;
};

#endif /* __STL_USE_STD_ALLOCATORS */

template <class _Tp, class _Alloc>
void 
_List_base<_Tp,_Alloc>::clear() 
{
  _List_node<_Tp>* __cur = (_List_node<_Tp>*) _M_node->_M_next;
  while (__cur != _M_node) {
    _List_node<_Tp>* __tmp = __cur;
    __cur = (_List_node<_Tp>*) __cur->_M_next;
    //先调用析构函数，然后释放空间
    destroy(&__tmp->_M_data);
    _M_put_node(__tmp);
  }
  //空表的条件设置
  _M_node->_M_next = _M_node;
  _M_node->_M_prev = _M_node;
}

template <class _Tp, class _Alloc = __STL_DEFAULT_ALLOCATOR(_Tp) >
class list : protected _List_base<_Tp, _Alloc> {
  typedef _List_base<_Tp, _Alloc> _Base;
protected:
  typedef void* _Void_pointer;

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 _List_node<_Tp> _Node;
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;

  typedef typename _Base::allocator_type allocator_type;
  allocator_type get_allocator() const { return _Base::get_allocator(); }

public:
  typedef _List_iterator<_Tp,_Tp&,_Tp*>             iterator;
  typedef _List_iterator<_Tp,const _Tp&,const _Tp*> const_iterator;

#ifdef __STL_CLASS_PARTIAL_SPECIALIZATION
  typedef reverse_iterator<const_iterator> const_reverse_iterator;
  typedef reverse_iterator<iterator>       reverse_iterator;
#else /* __STL_CLASS_PARTIAL_SPECIALIZATION */
  typedef reverse_bidirectional_iterator<const_iterator,value_type,
                                         const_reference,difference_type>
          const_reverse_iterator;
  typedef reverse_bidirectional_iterator<iterator,value_type,reference,
                                         difference_type>
          reverse_iterator; 
#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */

protected:
#ifdef __STL_HAS_NAMESPACES
  using _Base::_M_node;
  using _Base::_M_put_node;
  using _Base::_M_get_node;
#endif /* __STL_HAS_NAMESPACES */

protected:
  _Node* _M_create_node(const _Tp& __x)
  {
    _Node* __p = _M_get_node();
    __STL_TRY {
      construct(&__p->_M_data, __x);
    }
    __STL_UNWIND(_M_put_node(__p));
    return __p;
  }

  _Node* _M_create_node()
  {
    _Node* __p = _M_get_node();
    __STL_TRY {
      construct(&__p->_M_data);
    }
    __STL_UNWIND(_M_put_node(__p));
    return __p;
  }

public:
  explicit list(const allocator_type& __a = allocator_type()) : _Base(__a) {}

  iterator begin()             { return (_Node*)(_M_node->_M_next); }
  const_iterator begin() const { return (_Node*)(_M_node->_M_next); }

  iterator end()             { return _M_node; }
  const_iterator end() const { return _M_node; }

  reverse_iterator rbegin() 
    { return reverse_iterator(end()); }
  const_reverse_iterator rbegin() const 
    { return const_reverse_iterator(end()); }

  reverse_iterator rend()
    { return reverse_iterator(begin()); }
  const_reverse_iterator rend() const
    { return const_reverse_iterator(begin()); }

  bool empty() const { return _M_node->_M_next == _M_node; }
  size_type size() const {
    size_type __result = 0;
    distance(begin(), end(), __result);
    return __result;
  }
  size_type max_size() const { return size_type(-1); }

  reference front() { return *begin(); }
  const_reference front() const { return *begin(); }
  reference back() { return *(--end()); }
  const_reference back() const { return *(--end()); }

  void swap(list<_Tp, _Alloc>& __x) { __STD::swap(_M_node, __x._M_node); }

  iterator insert(iterator __position, const _Tp& __x) {
    _Node* __tmp = _M_create_node(__x);
    __tmp->_M_next = __position._M_node;
    __tmp->_M_prev = __position._M_node->_M_prev;
    ((_Node*) (__position._M_node->_M_prev))->_M_next = __tmp;
    __position._M_node->_M_prev = __tmp;
    return __tmp;
  }
  iterator insert(iterator __position) { return insert(__position, _Tp()); }
#ifdef __STL_MEMBER_TEMPLATES
  // Check whether it's an integral type.  If so, it's not an iterator.

  template<class _Integer>
  void _M_insert_dispatch(iterator __pos, _Integer __n, _Integer __x,
                          __true_type) {
    _M_fill_insert(__pos, (size_type) __n, (_Tp) __x);
  }

  template <class _InputIterator>
  void _M_insert_dispatch(iterator __pos,
                          _InputIterator __first, _InputIterator __last,
                          __false_type);

  template <class _InputIterator>
  void insert(iterator __pos, _InputIterator __first, _InputIterator __last) {
    typedef typename _Is_integer<_InputIterator>::_Integral _Integral;
    _M_insert_dispatch(__pos, __first, __last, _Integral());
  }

#else /* __STL_MEMBER_TEMPLATES */
  void insert(iterator __position, const _Tp* __first, const _Tp* __last);
  void insert(iterator __position,
              const_iterator __first, const_iterator __last);
#endif /* __STL_MEMBER_TEMPLATES */

  void insert(iterator __pos, size_type __n, const _Tp& __x)
    { _M_fill_insert(__pos, __n, __x); }
  void _M_fill_insert(iterator __pos, size_type __n, const _Tp& __x); 

  void push_front(const _Tp& __x) { insert(begin(), __x); }
  void push_front() {insert(begin());}
  void push_back(const _Tp& __x) { insert(end(), __x); }
  void push_back() {insert(end());}

  iterator erase(iterator __position) {
    _Node* __next_node = (_Node*) (__position._M_node->_M_next);
    _Node* __prev_node = (_Node*) (__position._M_node->_M_prev);
    
    __prev_node->_M_next = __next_node;
    __next_node->_M_prev = __prev_node;
    
    destroy(&__position._M_node->_M_data);
    _M_put_node(__position._M_node);
    
    return iterator(__next_node);
  }
  iterator erase(iterator __first, iterator __last);
  void clear() { _Base::clear(); }

  void resize(size_type __new_size, const _Tp& __x);
  void resize(size_type __new_size) { resize(__new_size, _Tp()); }

  void pop_front() { erase(begin()); }
  void pop_back() { 
    iterator __tmp = end();
    erase(--__tmp);
  }
  list(size_type __n, const _Tp& __value,
       const allocator_type& __a = allocator_type())
    : _Base(__a)
    { insert(begin(), __n, __value); }
  explicit list(size_type __n)
    : _Base(allocator_type())
    { insert(begin(), __n, _Tp()); }

#ifdef __STL_MEMBER_TEMPLATES

  // We don't need any dispatching tricks here, because insert does all of
  // that anyway.  
  template <class _InputIterator>
  list(_InputIterator __first, _InputIterator __last,
       const allocator_type& __a = allocator_type())
    : _Base(__a)
    { insert(begin(), __first, __last); }

#else /* __STL_MEMBER_TEMPLATES */

  list(const _Tp* __first, const _Tp* __last,
       const allocator_type& __a = allocator_type())
    : _Base(__a)
    { insert(begin(), __first, __last); }
  list(const_iterator __first, const_iterator __last,
       const allocator_type& __a = allocator_type())
    : _Base(__a)
    { insert(begin(), __first, __last); }

#endif /* __STL_MEMBER_TEMPLATES */
  list(const list<_Tp, _Alloc>& __x) : _Base(__x.get_allocator())
    { insert(begin(), __x.begin(), __x.end()); }

  ~list() { }

  list<_Tp, _Alloc>& operator=(const list<_Tp, _Alloc>& __x);

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 */

protected:
//transfer函数作为辅助函数使用，时间复杂度为O（1）
  void transfer(iterator __position, iterator __first, iterator __last) {
    if (__position != __last) {
      // Remove [first, last) from its old position.
      ((_Node*) (__last._M_node->_M_prev))->_M_next     = __position._M_node;
      ((_Node*) (__first._M_node->_M_prev))->_M_next    = __last._M_node;
      ((_Node*) (__position._M_node->_M_prev))->_M_next = __first._M_node; 

      // Splice [first, last) into its new position.
      _Node* __tmp = (_Node*) (__position._M_node->_M_prev);
      __position._M_node->_M_prev = __last._M_node->_M_prev;
      __last._M_node->_M_prev      = __first._M_node->_M_prev; 
      __first._M_node->_M_prev    = __tmp;
    }
  }

public:
//splice函数时间复杂度为O（1）
  void splice(iterator __position, list& __x) {
    if (!__x.empty()) 
      transfer(__position, __x.begin(), __x.end());
  }
  void splice(iterator __position, list&, iterator __i) {
    iterator __j = __i;
    ++__j;
    if (__position == __i || __position == __j) return;
    transfer(__position, __i, __j);
  }
  void splice(iterator __position, list&, iterator __first, iterator __last) {
    if (__first != __last) 
      transfer(__position, __first, __last);
  }
  void remove(const _Tp& __value);
  void unique();
  void merge(list& __x);
  void reverse();
  void sort();

#ifdef __STL_MEMBER_TEMPLATES
  template <class _Predicate> void remove_if(_Predicate);
  template <class _BinaryPredicate> void unique(_BinaryPredicate);
  template <class _StrictWeakOrdering> void merge(list&, _StrictWeakOrdering);
  template <class _StrictWeakOrdering> void sort(_StrictWeakOrdering);
#endif /* __STL_MEMBER_TEMPLATES */
};

template <class _Tp, class _Alloc>
inline bool 
operator==(const list<_Tp,_Alloc>& __x, const list<_Tp,_Alloc>& __y)
{
  typedef typename list<_Tp,_Alloc>::const_iterator const_iterator;
  const_iterator __end1 = __x.end();
  const_iterator __end2 = __y.end();

  const_iterator __i1 = __x.begin();
  const_iterator __i2 = __y.begin();
  while (__i1 != __end1 && __i2 != __end2 && *__i1 == *__i2) {
    ++__i1;
    ++__i2;
  }
  return __i1 == __end1 && __i2 == __end2;
}

template <class _Tp, class _Alloc>
inline bool operator<(const list<_Tp,_Alloc>& __x,
                      const list<_Tp,_Alloc>& __y)
{
  return lexicographical_compare(__x.begin(), __x.end(),
                                 __y.begin(), __y.end());
}

#ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER

template <class _Tp, class _Alloc>
inline bool operator!=(const list<_Tp,_Alloc>& __x,
                       const list<_Tp,_Alloc>& __y) {
  return !(__x == __y);
}

template <class _Tp, class _Alloc>
inline bool operator>(const list<_Tp,_Alloc>& __x,
                      const list<_Tp,_Alloc>& __y) {
  return __y < __x;
}

template <class _Tp, class _Alloc>
inline bool operator<=(const list<_Tp,_Alloc>& __x,
                       const list<_Tp,_Alloc>& __y) {
  return !(__y < __x);
}

template <class _Tp, class _Alloc>
inline bool operator>=(const list<_Tp,_Alloc>& __x,
                       const list<_Tp,_Alloc>& __y) {
  return !(__x < __y);
}

template <class _Tp, class _Alloc>
inline void 
swap(list<_Tp, _Alloc>& __x, list<_Tp, _Alloc>& __y)
{
  __x.swap(__y);
}

#endif /* __STL_FUNCTION_TMPL_PARTIAL_ORDER */

#ifdef __STL_MEMBER_TEMPLATES

template <class _Tp, class _Alloc> template <class _InputIter>
void 
list<_Tp, _Alloc>::_M_insert_dispatch(iterator __position,
                                      _InputIter __first, _InputIter __last,
                                      __false_type)
{
  for ( ; __first != __last; ++__first)
    insert(__position, *__first);
}

#else /* __STL_MEMBER_TEMPLATES */

template <class _Tp, class _Alloc>
void 
list<_Tp, _Alloc>::insert(iterator __position, 
                          const _Tp* __first, const _Tp* __last)
{
  for ( ; __first != __last; ++__first)
    insert(__position, *__first);
}

template <class _Tp, class _Alloc>
void 
list<_Tp, _Alloc>::insert(iterator __position,
                         const_iterator __first, const_iterator __last)
{
  for ( ; __first != __last; ++__first)
    insert(__position, *__first);
}

#endif /* __STL_MEMBER_TEMPLATES */

template <class _Tp, class _Alloc>
void 
list<_Tp, _Alloc>::_M_fill_insert(iterator __position,
                                  size_type __n, const _Tp& __x)
{
  for ( ; __n > 0; --__n)
    insert(__position, __x);
}

template <class _Tp, class _Alloc>
list<_Tp,_Alloc>::iterator list<_Tp, _Alloc>::erase(iterator __first, 
                                                    iterator __last)
{
  while (__first != __last)
    erase(__first++);
  return __last;
}

template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::resize(size_type __new_size, const _Tp& __x)
{
  iterator __i = begin();
  size_type __len = 0;
  for ( ; __i != end() && __len < __new_size; ++__i, ++__len)
    ;
  if (__len == __new_size)
    erase(__i, end());
  else                          // __i == end()
    insert(end(), __new_size - __len, __x);
}

template <class _Tp, class _Alloc>
list<_Tp, _Alloc>& list<_Tp, _Alloc>::operator=(const list<_Tp, _Alloc>& __x)
{
  if (this != &__x) {
    iterator __first1 = begin();
    iterator __last1 = end();
    const_iterator __first2 = __x.begin();
    const_iterator __last2 = __x.end();
    while (__first1 != __last1 && __first2 != __last2) 
      *__first1++ = *__first2++;
    if (__first2 == __last2)
      erase(__first1, __last1);
    else
      insert(__last1, __first2, __last2);
  }
  return *this;
}

template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::_M_fill_assign(size_type __n, const _Tp& __val) {
  iterator __i = begin();
  for ( ; __i != end() && __n > 0; ++__i, --__n)
    *__i = __val;
  if (__n > 0)
    insert(end(), __n, __val);
  else
    erase(__i, end());
}

#ifdef __STL_MEMBER_TEMPLATES

template <class _Tp, class _Alloc> template <class _InputIter>
void
list<_Tp, _Alloc>::_M_assign_dispatch(_InputIter __first2, _InputIter __last2,
                                      __false_type)
{
  iterator __first1 = begin();
  iterator __last1 = end();
  for ( ; __first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)
    *__first1 = *__first2;
  if (__first2 == __last2)
    erase(__first1, __last1);
  else
    insert(__last1, __first2, __last2);
}

#endif /* __STL_MEMBER_TEMPLATES */

template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::remove(const _Tp& __value)
{
  iterator __first = begin();
  iterator __last = end();
  while (__first != __last) {
    iterator __next = __first;
    ++__next;
    if (*__first == __value) erase(__first);
    __first = __next;
  }
}

template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::unique()
{
  iterator __first = begin();
  iterator __last = end();
  if (__first == __last) return;
  iterator __next = __first;
  while (++__next != __last) {
    if (*__first == *__next)
      erase(__next);
    else
      __first = __next;
    __next = __first;
  }
}

template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::merge(list<_Tp, _Alloc>& __x)
{
  iterator __first1 = begin();
  iterator __last1 = end();
  iterator __first2 = __x.begin();
  iterator __last2 = __x.end();
  while (__first1 != __last1 && __first2 != __last2)
    if (*__first2 < *__first1) {
      iterator __next = __first2;
      transfer(__first1, __first2, ++__next);
      __first2 = __next;
    }
    else
      ++__first1;
  if (__first2 != __last2) transfer(__last1, __first2, __last2);
}

template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::reverse() 
{
  // Do nothing if the list has length 0 or 1.
  if (_M_node->_M_next != _M_node &&
      ((_Node*) (_M_node->_M_next))->_M_next != _M_node) {
    iterator __first = begin();
    ++__first;
    while (__first != end()) {
      iterator __old = __first;
      ++__first;
      transfer(begin(), __old, __first);
    }
  }
}    

//一种针对链表排序很好的处理方法，时间复杂度为O(N*LOG(N),空间复杂度为O(1)；
//自底向上的归并排序策略
template <class _Tp, class _Alloc>
void list<_Tp, _Alloc>::sort()
{
  // Do nothing if the list has length 0 or 1.
  if (_M_node->_M_next != _M_node &&
      ((_Node*) (_M_node->_M_next))->_M_next != _M_node) {
    list<_Tp, _Alloc> __carry;
    list<_Tp, _Alloc> __counter[64];
    int __fill = 0;
    while (!empty()) {
      __carry.splice(__carry.begin(), *this, begin());
      int __i = 0;
      while(__i < __fill && !__counter[__i].empty()) {
        __counter[__i].merge(__carry);
        __carry.swap(__counter[__i++]);
      }
      __carry.swap(__counter[__i]);         
      if (__i == __fill) ++__fill;
    } 

    for (int __i = 1; __i < __fill; ++__i)
      __counter[__i].merge(__counter[__i-1]);
    swap(__counter[__fill-1]);
  }
}

#ifdef __STL_MEMBER_TEMPLATES

template <class _Tp, class _Alloc> template <class _Predicate>
void list<_Tp, _Alloc>::remove_if(_Predicate __pred)
{
  iterator __first = begin();
  iterator __last = end();
  while (__first != __last) {
    iterator __next = __first;
    ++__next;
    if (__pred(*__first)) erase(__first);
    __first = __next;
  }
}

template <class _Tp, class _Alloc> template <class _BinaryPredicate>
void list<_Tp, _Alloc>::unique(_BinaryPredicate __binary_pred)
{
  iterator __first = begin();
  iterator __last = end();
  if (__first == __last) return;
  iterator __next = __first;
  while (++__next != __last) {
    if (__binary_pred(*__first, *__next))
      erase(__next);
    else
      __first = __next;
    __next = __first;
  }
}

template <class _Tp, class _Alloc> template <class _StrictWeakOrdering>
void list<_Tp, _Alloc>::merge(list<_Tp, _Alloc>& __x,
                              _StrictWeakOrdering __comp)
{
  iterator __first1 = begin();
  iterator __last1 = end();
  iterator __first2 = __x.begin();
  iterator __last2 = __x.end();
  while (__first1 != __last1 && __first2 != __last2)
    if (__comp(*__first2, *__first1)) {
      iterator __next = __first2;
      transfer(__first1, __first2, ++__next);
      __first2 = __next;
    }
    else
      ++__first1;
  if (__first2 != __last2) transfer(__last1, __first2, __last2);
}

template <class _Tp, class _Alloc> template <class _StrictWeakOrdering>
void list<_Tp, _Alloc>::sort(_StrictWeakOrdering __comp)
{
  // Do nothing if the list has length 0 or 1.
  if (_M_node->_M_next != _M_node &&
      ((_Node*) (_M_node->_M_next))->_M_next != _M_node) {
    list<_Tp, _Alloc> __carry;
    list<_Tp, _Alloc> __counter[64];
    int __fill = 0;
    while (!empty()) {
      __carry.splice(__carry.begin(), *this, begin());
      int __i = 0;
      while(__i < __fill && !__counter[__i].empty()) {
        __counter[__i].merge(__carry, __comp);
        __carry.swap(__counter[__i++]);
      }
      __carry.swap(__counter[__i]);         
      if (__i == __fill) ++__fill;
    } 

    for (int __i = 1; __i < __fill; ++__i) 
      __counter[__i].merge(__counter[__i-1], __comp);
    swap(__counter[__fill-1]);
  }
}

#endif /* __STL_MEMBER_TEMPLATES */

#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_LIST_H */

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