私は doublelyLinkedList を作成しています。エラーは、私の getIterator メソッドに関係しています。私はこれを理解することはできません。誰か知っていますか？
Here is where the error is?
// ------------------------------------------------------------------------------
// Name: GetIterator
// Description: Generates an iterator pointing towards the current head node
// Arguments: None.
// Return Value: <Datatype> Iterator
// ------------------------------------------------------------------------------
DoublyListIterator<Datatype> getIterator()
{
return DoublyListIterator<Datatype>(this, m_head);
}
};
#ifndef DOUBLYLINKEDLIST_H
#define DOUBLYLINKEDLIST_H
#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
using namespace std;
template<class Datatype> class DoublyListNode;
template<class Datatype> class DoublyLinkedList;
template<class Datatype> class DoublyListIterator;
// -------------------------------------------------------
// Name: DListNode
// Description: This is the Doubly-linked list node class.
// -------------------------------------------------------
template<class Datatype>
class DListNode
{
public:
Datatype m_data;
DListNode<Datatype>* m_next;
DListNode<Datatype>* m_prev;
// ----------------------------------------------------------------
// Name: InsertAfter
// Description: This adds a node after the current node.
// Arguments: p_data - The data to store in the new node.
// Return Value: None.
// ----------------------------------------------------------------
void InsertAfter(Datatype p_data)
{
// create the new node.
DListNode<Datatype>* newNode= new DListNode<Datatype>;
newNode->m_data = p_data;
// make the new node point to the next node.
newNode->m_next = m_next;
newNode->m_prev = this;
// make the node before it, point to the new node
if(m_next != 0)
m_next->m_prev= newNode;
m_next = newNode;
}
// ----------------------------------------------------------------
// Name: InsertBefore
// Description: This adds a node before the current node.
// Arguments: p_data - The data to store in the new node.
// Return Value: None.
// ----------------------------------------------------------------
void InsertBefore(Datatype p_data)
{
//Create new Node
DListNode<Datatype>* newNode = new DListNode<Datatype>;
newNode->m_data = p_data;
//Set up new Node Pointers
newNode->m_next = this;
newNode->m_prev = m_prev;
//if theres a node before it, make it point to new node
if(m_prev != 0)
m_prev->m_next = newNode;
m_prev = newNode;
}
};
// -------------------------------------------------------------
// Name: DLinkedList
// Description: This is the Doubly-linked list container class.
// -------------------------------------------------------------
template<class Datatype>
class DoublyLinkedList
{
public:
DListNode<Datatype>* m_head;
DListNode<Datatype>* m_tail;
int m_count;
// -----------------------------------------------------------------------------------------
// Name: DLinkedList
// Description: Constructor, creates a head node, tail node & a count.
// Arguments: m_head: the head node of the list.
// m_tail: the tail node of the list.
// Return Value: None.
// -----------------------------------------------------------------------------------------
DoublyLinkedList()
{
m_head= 0;
m_tail= 0;
m_count= 0;
}
// -----------------------------------------------------------------------------------------
// Name: ~DLinkedList
// Description: Destructor, creates a pointer for the head node,
// deletes the value in the list and iterates.
// Arguments: m_head: the head node of the list.
// itr: moves through the list.
// Return Value: None.
// -----------------------------------------------------------------------------------------
~DoublyLinkedList()
{
// temporary node pointers.
DListNode<Datatype>* itr= m_head;
DListNode<Datatype>* next;
while(itr != 0)
{
// save the pointer to the next node.
next = itr->m_next;
// delete the current node.
delete itr;
// make the next node the current node.
itr= next;
}
}
// ----------------------------------------------------------------
// Name: Length
// Description: Gets the size of the list
// Arguments: None.
// Return Value: size of the list.
// ----------------------------------------------------------------
int Length()
{
return m_count;
}
// -------------------------------------------------------------------------------------
// Name: Append
// Description: This adds a node to the end of the list, then points to the newNode
// Arguments: p_data - The data to store in the new node.
// m_count is increased.
// Return Value: None.
// -------------------------------------------------------------------------------------
void Append(Datatype p_data)
{
if(m_head == 0)
{
// create a new head node.
m_head= m_tail= new DListNode<Datatype>;
m_head->m_data= p_data;
m_head->m_next= 0;
m_head->m_prev= 0;
}
else
{
// insert a new node after the tail and reset the tail.
m_tail->InsertAfter(p_data);
m_tail= m_tail->m_next;
}
m_count++;
}
// -----------------------------------------------------------------------------------
// Name: Prepend
// Description: This adds a node before the head node, then points to the newNode
// Arguments: p_data - The data to store in the new node.
// m_count is increased.
// Return Value: None.
// -----------------------------------------------------------------------------------
void Prepend(Datatype p_data)
{
// create the new node.
DListNode<Datatype>* newNode= new DListNode<Datatype>;
newNode->m_data= p_data;
newNode->m_next= m_head;
// set the head node and the tail node if needed.
m_head= newNode;
if(m_tail== 0)
m_tail= m_head;
m_count++;
}
// ----------------------------------------------------------------------------------------------------------------
// Name: Insert
// Description: Inserts data before the iterator, this works whether the iterator is backwards of forwards
// through the list.Inserts at the end of the list if iterator is invalid.
// Arguments: p_iterator: The iterator to insert before
// p_data: the data to insert
// Return Value: None.
// ----------------------------------------------------------------------------------------------------------------
void Insert(DoublyListIterator<Datatype>& p_itr, Datatype p_data)
{
if(p_itr.m_node != 0)
{
// insert the data before the iterator
p_itr.m_node->InsertBefore(p_data);
//if the iterator was at the head of the list,
//reset the head pointer
if(p_itr.m_node == m_head)
{
m_head = m_head->m_prev;
}
// increment the count
m_count++;
}
else
{
Append(p_data);
}
}
// -------------------------------------------------------------------------------------------------------
// Name: Remove
// Description: Removes the node that the iterator points to, moves iterator forward to the next node.
// Arguments: p_iterator: The iterator to remove
// isForward: Tells which direction the iterator was going through the list
// Return Value: None.
// -------------------------------------------------------------------------------------------------------
void Remove(DoublyListIterator<Datatype>& p_itr, bool isForward)
{
// temporary node pointer.
DListNode<Datatype>* newNode;
// if node is invalid, do nothing.
if(p_itr.m_node == 0)
return;
// save the pointer to the node we want to delete.
newNode = p_itr.m_node;
// if the node we want to remove is the head or the tail
// nodes, then move the head or tail to the next or
// previous node.
if(newNode == m_head)
{
m_head = m_head->m_next;
}
else if(newNode == m_tail)
{
m_tail = m_tail->m_prev;
}
// if moving from head to tail, move the iterator forward
// to the next valid node
if(isForward == true)
{
p_itr.Forth();
}
//else, we are moving from tail to head, so move the iterator
// to the previous valid node
else
{
p_itr.Back();
}
if(newNode->m_prev != 0)
newNode->m_prev->m_next = newNode->m_next;
else if(newNode->m_next != 0)
newNode->m_next->m_prev = newNode->m_prev;
// delink and delete the node.
delete newNode;
// if the head is 0, then set the tail to 0 as well.
if(m_head == 0)
m_tail = 0;
m_count--;
}
// -----------------------------------------------------------------------------------
// Name: RemoveHead
// Description: Removes the Head of the List and points to the New Node
// Arguments: None
// Return Value: None.
// -----------------------------------------------------------------------------------
void RemoveHead()
{
DListNode<Datatype>* newNode = 0;
if(m_head!= 0)
{
// make node point to the next node.
newNode = m_head->m_next;
// then delete the head and make the pointer
// point to node.
delete m_head;
m_head= newNode;
// if the head is null, then you’ve just deleted the only node
// in the list. set the tail to 0.
if(m_head== 0)
m_tail= 0;
m_count--;
}
}
// -----------------------------------------------------------------------------------------
// Name: RemoveTail
// Description: The tail node is removed - but at a much slower pace than the head node,
// this is because the node has to search through the list to find the node before the tail
// node and set it to the new tail node then deleting the tail node
// Arguments: None.
// Return Value: None.
// -----------------------------------------------------------------------------------------
void RemoveTail()
{
DListNode<Datatype>* newNode = m_head;
// if the list isn’t empty, then remove a node.
if(m_head!= 0)
{
// if the head is equal to the tail, then
// the list has 1 node, and you are removing it.
if(m_head == m_tail)
{
// delete the node and set both pointers
// to 0.
delete m_head;
m_head= m_tail= 0;
}
else
{
// skip ahead until you find the node
// right before the tail node
while(newNode->m_next!= m_tail)
newNode = newNode->m_next;
// make the tail point to the node before the
// current tail and delete the old tail.
m_tail= newNode;
delete newNode->m_next;
newNode->m_next= 0;
}
m_count--;
}
}
// ------------------------------------------------------------------------------
// Name: GetIterator
// Description: Generates an iterator pointing towards the current head node
// Arguments: None.
// Return Value: <Datatype> Iterator
// ------------------------------------------------------------------------------
DoublyListIterator<Datatype> getIterator()
{
return DoublyListIterator<Datatype>(this, m_head);
}
};
// ----------------------------------------------------------
// Name: DoublyListIterator
// Description: This is the basic linked list iterator class.
// ----------------------------------------------------------
template<class Datatype>
class DoublyListIterator
{
public:
// ----------------------------------------------------------------
// Name: m_node
// Description: pointer to the current node
// ----------------------------------------------------------------
DoublyListNode<Datatype>* m_node;
// ----------------------------------------------------------------
// Name: m_list
// Description: pointer to the current list.
// ----------------------------------------------------------------
DoublyLinkedList<Datatype>* m_list;
// -----------------------------------------------------------------------------------------
// Name: DListIterator
// Description: Constructor, creates an iterator that points to the given list and node.
// Arguments: p_list: pointer to the list the iterator belongs to.
// p_node: pointer to the current node.
// Return Value: None.
// -----------------------------------------------------------------------------------------
DoublyListIterator(DoublyLinkedList<Datatype>* p_list= 0, DoublyListNode<Datatype>* p_node= 0)
{
m_list= p_list;
m_node= p_node;
}
// ------------------------------------------------------------------
// Name: Start
// Description: Resets the iterator to the beginning of the list.
// Arguments: None.
// Return Value: None.
// ------------------------------------------------------------------
void Start()
{
if(m_list!= 0)
m_node= m_list->m_head;
}
// ----------------------------------------------------------------
// Name: End
// Description: Resets the iterator to the end of the list
// Arguments: None.
// Return Value: None.
// ----------------------------------------------------------------
void End()
{
if(m_list!= 0)
m_node = m_list->m_tail;
}
// ----------------------------------------------------------------
// Name: Forth
// Description: Moves the iterator forward by one position
// Arguments: None.
// Return Value: None.
// ----------------------------------------------------------------
void Forth()
{
if(m_node!= 0)
m_node= m_node->m_next;
}
// ----------------------------------------------------------------
// Name: Back
// Description: Moves the iterator backward by one position.
// Arguments: None.
// Return Value: None.
// ----------------------------------------------------------------
void Back()
{
if(m_node!= 0)
m_node = m_node->m_prev;
}
// ----------------------------------------------------------------
// Name: Item
// Description: Gets the item that the iterator is pointing to.
// Arguments: None.
// Return Value: Reference to the data in the node.
// ----------------------------------------------------------------
Datatype& Item()
{
return m_node->m_data;
}
// ----------------------------------------------------------------
// Name: Valid
// Description: Determines if the node is valid.
// Arguments: None.
// Return Value: true if valid
// ----------------------------------------------------------------
bool Valid()
{
return (m_node!= 0);
}
// ----------------------------------------------------------------
// Name: operator==
// Description: Determines if two iterators point to the same node.
// Arguments: None.
// Return Value: true if they point to the same node.
// ----------------------------------------------------------------
bool operator==( DoublyListIterator<Datatype>& p_rhs )
{
if( m_node == p_rhs.m_node && m_list == p_rhs.m_list )
{
return true;
}
return false;
}
};
#endif
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