Smart Array (Linked List template implementation using C++)

As we have discussed about the Smart Array (Linked List) in our previous post and showed the Node class as well as the header file for the linked list. Below is the actual implementation of Linked List template in C++.

Any questions welcomed!

#include “list.h”

template <class T>

// in constructor we add a head node in the class as well as the cursor which we called current node.

// head node and current node set to null as there are no other nodes to point to.

List<T>::List()

{

headNode   =   new Node<T>();

headNode->setNext(NULL);

headNode->setLast(NULL);

currentNode   =   NULL;

size   =   0;

}

//in destructor we do memory management as we did made nodes dynamically.

template <class T>

List<T>::~List ()

{

while (size != 0)

{

remove_node();

}

delete currentNode;

delete headNode;

}

// this function simply call remove_node function until all nodes are deleted.

template <class T>

bool List<T>::clear_list ()

{

while (size != 0)

{

remove_node ();

}

delete currentNode;

}

// this is the main addition of a node function.

template <class T>

void   List<T>::add (T addObject)

{

Node<T> *newNode   =   new   Node<T>();

newNode->set(addObject);

size ++;

if(currentNode   !=   NULL) // in case we already have other nodes in the list

{

lastNode = currentNode;

newNode->setNext(currentNode->getNext()); // pointer will be adjusted for the new node.

if (newNode->getNext()!= NULL) // if the node is not at the end of the list.

{

currentNode = currentNode->getNext();

currentNode->setLast(newNode);

}

newNode->setLast(lastNode);

currentNode   =   newNode;

lastNode->setNext(newNode);

newNode->setIndex(size);

}

else // if this the very first node to be added in the list. this else part will be executed once in the life span of list.

{

newNode->setNext(NULL);

headNode->setNext(newNode);

newNode->setLast(headNode);

currentNode   =   newNode;

newNode->setIndex(size);

}

}

// this function return the current node value.

template <class T>

T   List<T>::get()

{

if (currentNode  !=  NULL)

{

return   currentNode->get();

}if (currentNode == headNode) // if cursor is pointing towards head node. we cannot return anything as head node doesn’t

// have any value.

{

return false;

}

}

// move the cursor to next node only if the cursor is not reached on the last node.

template <class T>

bool List<T>::move_next()

{

if (currentNode->getNext()  ==  NULL) return false   ;

currentNode  =  currentNode->getNext();

}

//move the cursor to backwards only if the cursor is not reached till head node.

template <class T>

bool List<T>::move_back ()

{

if (currentNode->getLast() == headNode) return false;

currentNode = currentNode->getLast();

}

//move the cursor to very first node after head node, if there are any nodes in the list.

template <class T>

bool List<T>::move_first()

{

if (headNode->getNext()!=NULL)

currentNode = headNode->getNext();

}

//move the cursor to last node.

template <class T>

bool List<T>::move_last()

{

while (currentNode->getNext() != NULL)

{

currentNode= currentNode->getNext();

}

return currentNode;

}

//delete current node where cursor pointing to.

template <class T>

bool List<T>::remove_node()

{

Node<T> *temp = currentNode;

if (currentNode != NULL) // if cursor is actually pointing to a valid node

{

if (currentNode->getLast() == headNode) // if cursor is on the very first node after head node.

{

currentNode = headNode;

currentNode->setNext(NULL);

currentNode->setLast(NULL);

delete temp;

size–;

return true;

}else if (currentNode->getNext() == NULL) //if cursor is pointing to the very last node of the list.

{

move_back();

currentNode->setNext(NULL);

delete temp;

size–;

return true;

}else // if the cursor is not at the start or end of the list but somewhere in the middle.

{

move_back();

currentNode->setNext(temp->getNext());

move_next();

currentNode->setLast(temp->getLast());

delete temp;

size–;

return true;

}

}

}

//move the cursor to next node.

template <class T>

Node<T> List<T>::operator++()

{

move_next();

return *currentNode;

}

//move theh cursor to last node.

template <class T>

Node<T> List<T>::operator–()

{

move_back();

return *currentNode;

}

// add one node and assign rvalue to it. the name of list instance is used as lvalue.

template <class T>

Node<T> List<T>::operator=(T i)

{

add(i);

}

//cout object can be used to display list values.

template <class T>

std::ostream& operator << (std::ostream& leftOpr, List<T>& rhs)

{

leftOpr << rhs.get();

return leftOpr;

}

//cin can be used to add one node and assign it a value directing getting input from user.

template <class T>

std::istream& operator >> (std::istream& leftOpr, List<T>& rhs)

{

int i = 0;

leftOpr >> i;

rhs.add(i);

return leftOpr;

}

//return size of the list. number of nodes in the list.

template <class T>

int List<T>::get_size()

{

return size;

}

//return node value by index.

template <class T>

Node<T> List<T>::return_node(int i)

{

move_first();

while (currentNode->getNext() != NULL)

{

if (currentNode->getIndex() == i)

return *currentNode;

else

move_next();

}

}

//brackets can be used to access list elements by giving index as used in simple array.

template <class T>

Node<T> List<T>::operator[](int i)

{

return_node(i);

}

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About Khuram Ali

Programming... Programming and Programming...!!!

Posted on March 27, 2013, in A library re-written., C++, Data Structures and tagged , , , , . Bookmark the permalink. 4 Comments.

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