双线链表
双向链表的特点：
1、以节点为单位，每个节点有上个节点指针和下个节点指针
2、至少包含头节点和尾节点
3、添加节点时先改变新增节点的上下节点指针指向，后修改前后节点的指针指向为当前节点
4、删除节点时修改当前节点的前后节点指向，然后删除当前节点
5、迭代器用来封装节点数据，并提供了操作符的能力，如*，++，==，!=
6、列表的操作有：取头，取尾，删头，删尾，删指定位置，加头，加尾，加指定位置
template
class List
{
private:
struct Node
{
Object data;
Node *prev;
Node *next;
Node(const Object &d = Object(), Node *p = NULL, Node *n = NULL)
: data(d), prev(p), next(n)
{
}
};
public:
class const_iterator
{
public:
const_iterator() : current(NULL)
{
}
const Object &operator* () const
{
return retrieve();
}
const_iterator & operator++ ()
{
current = current->next;
return *this;
}
const_iterator operator++ (int)
{
const_iterator old = *this;
++(*this);
return old;
}
bool operator == (const const_iterator &rhs) const
{
return current == rhs.current;
}
bool operator != (const const_iterator &rhs) const
{
return !(*this == rhs);
}
protected:
Node *current;
Object &retrieve() const
{
return current->data;
}
const_iterator(Node *p) : current(p)
{
}
friend class List < Object >;
};
class iterator : public const_iterator
{
public:
iterator()
{
}
Object & operator* ()
{
return retrieve();
}
iterator &operator++()
{
current = current->next;
return *this;
}
iterator operator++ (int)
{
iterator old = *this;
++(*this);
return old;
}
protected:
iterator(Node *p) : const_iterator(p)
{
}
friend class List < Object >;
};
public:
List()
{
init();
}
~List()
{
clear();
delete head;
delete tail;
}
List(const List &rhs)
{
init();
*this = rhs;
}
const List &operator = (const List &rhs)
{
if (this == &rhs)
{
return *this;
}
clear();
for (const_iterator itr = rhs.begin(); itr != rhs.end(); ++itr)
{
push_back(*itr);
}
return *this;
}
iterator begin()
{
return iterator(head->next);
}
const_iterator begin() const
{
return const_iterator(head->next);
}
iterator end()
{
return iterator(tail);
}
const_iterator end() const
{
return const_iterator(tail);
}
int size() const
{
return theSize;
}
bool empty() const
{
return size() == 0;
}
void clear()
{
while (!empty())
pop_front();
}
Object &front()
{
return *begin();
}
const Object & front() const
{
return *begin();
}
Object &back()
{
return *--end();
}
const Object &back() const
{
return *--end();
}
void push_front(const Object &x)
{
insert(begin(), x);
}
void push_back(const Object &x)
{
insert(end(), x);
}
void pop_front()
{
erase(begin());
}
void pop_back()
{
erase(--end());
}
iterator insert(iterator itr, const Object &x)
{
Node *p = itr.current;
theSize++;
return iterator(p->prev = p->prev->next = new Node(x, p->prev, p));
}
iterator erase(iterator itr)
{
Node *p = itr.current;
iterator retVal(p->next);
p->prev->next = p->next;
p->next->prev = p->prev;
delete p;
theSize--;
return retVal;
}
iterator erase(iterator start, iterator end)
{
for (iterator itr = start; itr != end;)
{
itr = erase(itr);
}
return end;
}
private:
int theSize;
Node *head;
Node *tail;
void init()
{
theSize = 0;
head = new Node;
tail = new Node;
head->next = tail;
tail->prev = head;
}};
int main()
{
List<int> nList;
nList.push_back(1);
nList.push_back(2);
nList.push_back(3);
nList.push_back(4);
for (List<int>::const_iterator itr = nList.begin(); itr != nList.end(); itr++)
{
LOG_INFO("itr vaule:" << *itr);
}
//
for (List<int>::iterator itr = nList.begin(); itr != nList.end(); )
{
nList.erase(itr++);
}
LOG_INFO("List size:" << nList.size());
reutrn 0;}
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