将新的节点插入双向链表的时候:
iterator insert(iterator itr,const Object & x)//向双向链表中插入一个x节点
{
Node *p = itr.current;
theSize++;
return iterator(p->prev = p->prev->next = new Node(x,p->prev,p));
}
LIST类的删除节点的过程:
//删除双向链表中的一个节点
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 = from;itr != to; )
itr = erase(itr);
return to;
}
传递给erase insert的迭代器可能没有初始化 或者 这个迭代器是错误的表达,因此需要一个检测:
protected:
const List<Object> *theList;
Node *current;
const_iterator(const List<Object> & lst,Node *p):
theList(&lst),current(p)'
{
}
void assertIsValid() const
{
if(theList == NULL || current == NULL || current == theList->head)
throw IteratorOutOfBoundsException();
}
带有附加错误检测的insert类:
iterator insert(iterator itr.const Object & x)
{
itr.assertIsValid();
if(itr.theList !=this)
throw IteratorMismatchException();
Node *p = itr.current;
theSize++;
return iterator(*this,p->prev=p->prev->next=new Node (x,p->prev,p));
}