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list

list<int> L;
L.push_back(0);
L.push_front(1);
L.insert(++L.begin(), 2);
copy(L.begin(), L.end(), ostream_iterator<int>(cout, " "));
// The values that are printed are 1 2 0
示例2：
#include <iostream>
#include <iterator>
#include <list>
#include <numeric>
#include <algorithm>


using namespace std;


list<int> mylist1, mylist2;


void display(){
	cout << "-------------------------------------------------------" << endl;
	copy(mylist1.begin(), mylist1.end(), ostream_iterator<int>(cout, " "));
	cout << endl;
	copy(mylist2.begin(), mylist2.end(), ostream_iterator<int>(cout, " "));
	cout << endl;
}


int main(){
	list<int>::iterator it;
	for(int i = 1; i <= 4; i++) mylist1.push_back(i); //1 2 3 4
	for(int i = 1; i <= 3; i++) mylist2.push_back(i * 10); // 10 20 30
	it = mylist1.begin();
	++it; // it 指向元素 2
	display();
	mylist1.splice(it, mylist2);
	display();	
	/* mylist1: 1 10 20 30 2 3 4 
	   mylist2: 空
	   it 还是指向元素 2
	*/					
	mylist2.splice(mylist2.begin(), mylist1, it);
	display();
	/* mylist1: 1 10 20 30 3 4 
	   mylist2: 2
	   it 现在 invalid 
	*/					


	it = mylist1.begin();
	advance(it, 3);
	mylist1.splice(mylist1.begin(), mylist1, it, mylist1.end());
	display();
	it = mylist1.begin();
	advance(it, 3);
	list<int>::iterator pos = mylist1.begin();
	advance(pos,4);
	mylist1.splice(pos, mylist1, it, mylist1.end()); //出错了,position 不能位于 [first, last) 之内 --> 感觉这样设计不好，不能编译期提醒，至少要在运行期提醒吧。。。
	display();
	
}

#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
#endif


//list的节点，这是一个双向链表
template <class T>
struct __list_node {
  typedef void* void_pointer;
  void_pointer next;
  void_pointer prev;
  T data;
};
//list迭代器的设计。(vector的迭代器不需要单独设计，用原生指针就可以)
template<class T, class Ref, class Ptr>
struct __list_iterator {
  typedef __list_iterator<T, T&, T*>             iterator;
  typedef __list_iterator<T, const T&, const T*> const_iterator;
  typedef __list_iterator<T, Ref, Ptr>           self;


  typedef bidirectional_iterator_tag iterator_category;
  typedef T value_type;
  typedef Ptr pointer;
  typedef Ref reference;
  typedef __list_node<T>* link_type;
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;


  link_type node; // 指向 list 节点的指针


  __list_iterator(link_type x) : node(x) {}
  __list_iterator() {}
  __list_iterator(const iterator& x) : node(x.node) {}


  bool operator==(const self& x) const { return node == x.node; }
  bool operator!=(const self& x) const { return node != x.node; }
  //取节点的数据值
  reference operator*() const { return (*node).data; }


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


  //迭代器累加 1， 前进一个节点
  self& operator++() { 
    node = (link_type)((*node).next);
	// 因为 __list_node 里的 prev 和 next 的类型是 void * ，
	//所以还要将它们显示转换为 link_type 类型，即 __list_node * 类型
    return *this;
  }
  self operator++(int) { 
    self tmp = *this;
    ++*this;
    return tmp;
  }
  //迭代器递减 1，后退一个节点
  self& operator--() { 
    node = (link_type)((*node).prev);
    return *this;
  }
  self operator--(int) { 
    self tmp = *this;
    --*this;
    return tmp;
  }
};


#ifndef __STL_CLASS_PARTIAL_SPECIALIZATION


template <class T, class Ref, class Ptr>
inline bidirectional_iterator_tag
iterator_category(const __list_iterator<T, Ref, Ptr>&) {
  return bidirectional_iterator_tag();
}


template <class T, class Ref, class Ptr>
inline T*
value_type(const __list_iterator<T, Ref, Ptr>&) {
  return 0;
}


template <class T, class Ref, class Ptr>
inline ptrdiff_t*
distance_type(const __list_iterator<T, Ref, Ptr>&) {
  return 0;
}


#endif /* __STL_CLASS_PARTIAL_SPECIALIZATION */


//list的数据结构
template <class T, class Alloc = alloc>
class list {
protected:
  typedef void* void_pointer;
  typedef __list_node<T> list_node;
  //空间配置器，每次配置一个节点大小
  typedef simple_alloc<list_node, Alloc> list_node_allocator;
public:      
  typedef T 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* link_type;
  typedef size_t size_type;
  typedef ptrdiff_t difference_type;


public:
  typedef __list_iterator<T, T&, T*>             iterator;
  typedef __list_iterator<T, const T&, const T*> 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:
  //配置一个节点并传回
  link_type get_node() { return list_node_allocator::allocate(); }
  //释放 p 指向的节点空间
  void put_node(link_type p) { list_node_allocator::deallocate(p); }
  //配置并构造一个节点使它的值为 x
  link_type create_node(const T& x) {
    link_type p = get_node();
    __STL_TRY {
      construct(&p->data, x);
    }
    __STL_UNWIND(put_node(p));
    return p;
  }
  //析构并释放一个节点
  void destroy_node(link_type p) {
    destroy(&p->data);
    put_node(p);
  }


protected:
  void empty_initialize() { 
    node = get_node(); //配置一个节点空间，令 node 指向它
    node->next = node; // 令 node 的头尾都指向自己，不设元素值
    node->prev = node;
  }


  void fill_initialize(size_type n, const T& value) {
    empty_initialize();
    __STL_TRY {
      insert(begin(), n, value);
    }
    __STL_UNWIND(clear(); put_node(node));
  }


#ifdef __STL_MEMBER_TEMPLATES
  template <class InputIterator>
  void range_initialize(InputIterator first, InputIterator last) {
    empty_initialize();
    __STL_TRY {
      insert(begin(), first, last);
    }
    __STL_UNWIND(clear(); put_node(node));
  }
#else  /* __STL_MEMBER_TEMPLATES */
  void range_initialize(const T* first, const T* last) {
    empty_initialize();
    __STL_TRY {
      insert(begin(), first, last);
    }
    __STL_UNWIND(clear(); put_node(node));
  }
  void range_initialize(const_iterator first, const_iterator last) {
    empty_initialize();
    __STL_TRY {
      insert(begin(), first, last);
    }
    __STL_UNWIND(clear(); put_node(node));
  }
#endif /* __STL_MEMBER_TEMPLATES */


protected:
  link_type node; //只要一个指针，便可表示整个环状双向链表。
  // node指向刻意置于尾端的一个空白节点，满足"前闭后开"


public:
  list() { empty_initialize(); } // 产生一个空链表


  iterator begin() { return (link_type)((*node).next); }
  const_iterator begin() const { return (link_type)((*node).next); }
  iterator end() { return node; }
  const_iterator end() const { return 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 node->next == 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<T, Alloc>& x) { __STD::swap(node, x.node); }
  //在迭代器 positioni 所指空间插入一个节点，内容为 x
  iterator insert(iterator position, const T& x) {
    //使用 create_node 配置并构造一个节点，让它的值为 x
	link_type tmp = create_node(x);
	//调整双向指针，使 tmp 插入进去
    tmp->next = position.node;
    tmp->prev = position.node->prev;
    (link_type(position.node->prev))->next = tmp;
    position.node->prev = tmp;
    return tmp;
  }
  iterator insert(iterator position) { return insert(position, T()); }
#ifdef __STL_MEMBER_TEMPLATES
  template <class InputIterator>
  void insert(iterator position, InputIterator first, InputIterator last);
#else /* __STL_MEMBER_TEMPLATES */
  void insert(iterator position, const T* first, const T* last);
  void insert(iterator position,
              const_iterator first, const_iterator last);
#endif /* __STL_MEMBER_TEMPLATES */
  void insert(iterator pos, size_type n, const T& x);
  void insert(iterator pos, int n, const T& x) {
    insert(pos, (size_type)n, x);
  }
  void insert(iterator pos, long n, const T& x) {
    insert(pos, (size_type)n, x);
  }


  void push_front(const T& x) { insert(begin(), x); }
  void push_back(const T& x) { insert(end(), x); }
  iterator erase(iterator position) {
    link_type next_node = link_type(position.node->next);
    link_type prev_node = link_type(position.node->prev);
    prev_node->next = next_node;
    next_node->prev = prev_node;
    destroy_node(position.node);
    return iterator(next_node);
  }
  iterator erase(iterator first, iterator last);
  void resize(size_type new_size, const T& x);
  void resize(size_type new_size) { resize(new_size, T()); }
  void clear();


  void pop_front() { erase(begin()); } //移除头节点
  void pop_back() {  //移除尾节点 其实可能直接 erase(--end()); 不过效果一样
    iterator tmp = end();
    erase(--tmp);
  }
  list(size_type n, const T& value) { fill_initialize(n, value); }
  list(int n, const T& value) { fill_initialize(n, value); }
  list(long n, const T& value) { fill_initialize(n, value); }
  explicit list(size_type n) { fill_initialize(n, T()); }


#ifdef __STL_MEMBER_TEMPLATES
  template <class InputIterator>
  list(InputIterator first, InputIterator last) {
    range_initialize(first, last);
  }


#else /* __STL_MEMBER_TEMPLATES */
  list(const T* first, const T* last) { range_initialize(first, last); }
  list(const_iterator first, const_iterator last) {
    range_initialize(first, last);
  }
#endif /* __STL_MEMBER_TEMPLATES */
  list(const list<T, Alloc>& x) {
    range_initialize(x.begin(), x.end());
  }
  ~list() {
    clear();
    put_node(node);
  }
  list<T, Alloc>& operator=(const list<T, Alloc>& x);


protected:
  //将某连续范围[first, last)的元素迁移到某个特定位置 position 之前
  //非公开接口
  void transfer(iterator position, iterator first, iterator last) {
    if (position != last) { //如果 position == last 那就不用迁移了
      (*(link_type((*last.node).prev))).next = position.node;
      (*(link_type((*first.node).prev))).next = last.node;
      (*(link_type((*position.node).prev))).next = first.node;  
      link_type tmp = link_type((*position.node).prev);
      (*position.node).prev = (*last.node).prev;
      (*last.node).prev = (*first.node).prev; 
      (*first.node).prev = tmp;
    }
  }


public:
  //将 x 接合于 position 所指位置之前。 x 必须不同于 *this --> 这样限制 x 好吗？ 不应该提前到编译期提醒客户端吗？我试了下 x 等于 *this，运行没出错
  void splice(iterator position, list& x) {
    if (!x.empty()) 
      transfer(position, x.begin(), x.end());
  }
  //将 i 所指元素接合于 position 所指位置之前。 position 和 i 可指向同一个 list
  // ?? 这里 list &参数有什么用？ --> 我感觉没用，有迭代器 i 就够了
  void splice(iterator position, list&, iterator i) {
    iterator j = i;
    ++j;
    if (position == i || position == j) return; //transfer 里有判断 position == j 的情况，没判断 position  == i 的情况，而将自己移到自己前面什么都不用做
    transfer(position, i, j);
  }
  //将 [first, last) 内的所有元素接合于 position 所指位置之前
  // position 和 [first, last) 可指向同一个 list,
  // 但 position 不能位于 [first, last) 之内
  void splice(iterator position, list&, iterator first, iterator last) {
    if (first != last) 
      transfer(position, first, last);
  }
  void remove(const T& 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 */


  friend bool operator== __STL_NULL_TMPL_ARGS (const list& x, const list& y);
};


template <class T, class Alloc>
inline bool operator==(const list<T,Alloc>& x, const list<T,Alloc>& y) {
  typedef typename list<T,Alloc>::link_type link_type;
  link_type e1 = x.node;
  link_type e2 = y.node;
  link_type n1 = (link_type) e1->next;
  link_type n2 = (link_type) e2->next;
  for ( ; n1 != e1 && n2 != e2 ;
          n1 = (link_type) n1->next, n2 = (link_type) n2->next)
    if (n1->data != n2->data)
      return false;
  return n1 == e1 && n2 == e2;
}


template <class T, class Alloc>
inline bool operator<(const list<T, Alloc>& x, const list<T, Alloc>& y) {
  return lexicographical_compare(x.begin(), x.end(), y.begin(), y.end());
}


#ifdef __STL_FUNCTION_TMPL_PARTIAL_ORDER


template <class T, class Alloc>
inline void swap(list<T, Alloc>& x, list<T, Alloc>& y) {
  x.swap(y);
}


#endif /* __STL_FUNCTION_TMPL_PARTIAL_ORDER */


#ifdef __STL_MEMBER_TEMPLATES


template <class T, class Alloc> template <class InputIterator>
void list<T, Alloc>::insert(iterator position,
                            InputIterator first, InputIterator last) {
  for ( ; first != last; ++first)
    insert(position, *first);
}


#else /* __STL_MEMBER_TEMPLATES */


template <class T, class Alloc>
void list<T, Alloc>::insert(iterator position, const T* first, const T* last) {
  for ( ; first != last; ++first)
    insert(position, *first);
}


template <class T, class Alloc>
void list<T, Alloc>::insert(iterator position,
                            const_iterator first, const_iterator last) {
  for ( ; first != last; ++first)
    insert(position, *first);
}


#endif /* __STL_MEMBER_TEMPLATES */


template <class T, class Alloc>
void list<T, Alloc>::insert(iterator position, size_type n, const T& x) {
  for ( ; n > 0; --n)
    insert(position, x);
}


template <class T, class Alloc>
list<T,Alloc>::iterator list<T, Alloc>::erase(iterator first, iterator last) {
  while (first != last) erase(first++);
  return last;
}


template <class T, class Alloc>
void list<T, Alloc>::resize(size_type new_size, const T& 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 T, class Alloc> 
void list<T, Alloc>::clear()
{
  link_type cur = (link_type) node->next;
  while (cur != node) { //遍历每一个节点
    link_type tmp = cur;
    cur = (link_type) cur->next; 
    destroy_node(tmp); //析构并释放一个节点
  }
  node->next = node; //恢复空链表时的节点状态
  node->prev = node;
}


template <class T, class Alloc>
list<T, Alloc>& list<T, Alloc>::operator=(const list<T, 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;
}
//将数值为 value 之所有元素移除
template <class T, class Alloc>
void list<T, Alloc>::remove(const T& value) {
  iterator first = begin();
  iterator last = end();
  while (first != last) {
    iterator next = first;
    ++next;
    if (*first == value) erase(first);
    first = next;
  }
}
//移除连续相同的元素，只保留一个
template <class T, class Alloc>
void list<T, Alloc>::unique() {
  iterator first = begin();
  iterator last = end();
  if (first == last) return; //空链表，什么都不必做
  iterator next = first;   
  while (++next != last) { //遍历每一个节点
    if (*first == *next) //相同移除之
      erase(next); 
    else //不同调整指针指向
      first = next;
    next = first;
  }
}


template <class T, class Alloc>
void list<T, Alloc>::merge(list<T, 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);
}


// reverse() 将 *this 的内容逆向重置
template <class T, class Alloc>
void list<T, Alloc>::reverse() {
  if (node->next == node || link_type(node->next)->next == node) return;
  iterator first = begin();
  ++first;
  while (first != end()) {
    iterator old = first;
    ++first;
    transfer(begin(), old, first);
  }
}    


/* list 不能使用 STL 算法 sort()， 必须使用自己的 sort() 成员函数
 因为 STL 算法 sort() 只接受 RandomAccessItertor 
 ？？ STL 算法 sort() 为什么不设计接受 BidirectionalIterator 
 不过我觉得即使 STL 算法 sort() 接受 BidirectionalIterator ， 它里面实现也是
 用类似 iter_swap 的方法，这里也要针对链表的特点重新写 sort() 函数
/*
template <class T, class Alloc>
void list<T, Alloc>::sort() {
  //
  if (node->next == node || link_type(node->next)->next == node) return;
  list<T, Alloc> carry;
  list<T, 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 T, class Alloc> template <class Predicate>
void list<T, 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 T, class Alloc> template <class BinaryPredicate>
void list<T, Alloc>::unique(BinaryPredicate binary_pred) {
  iterator first = begin();
  iterator last = end()  while (++next != last) {
    if (binary_pred(*first, *next))
      erase(next);
    else
      first = next;
    next = first;
  }
}


template <class T, class Alloc> template <class StrictWeakOrdering>
void list<T, Alloc>::merge(list<T, 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 T, class Alloc> template <class StrictWeakOrdering>
void list<T, Alloc>::sort(StrictWeakOrdering comp) {
  if (node->next == node || link_type(node->next)->next == node) return;
  list<T, Alloc> carry;
  list<T, 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
#endif


__STL_END_NAMESPACE 


#endif /* __SGI_STL_INTERNAL_LIST_H */


// Local Variables:
// mode:C++
// End: