Write a copy constructor for the linked list below. Use the following test program to test the copy constructor. ( I apologize in advace for making it so long. I am unable to upload the files.)

/* The test file, header file and class declarations are three seperate files, but they will be added together here*/

//Header File:

#ifndef LIST_H #define LIST_H

#include

using namespace std;

class List; class Iterator;

class Node { public: /** Constructs a node with a given data value. @param element the data to store in this node */ Node(string element); private: string data; Node* previous; Node* next; friend class List; friend class Iterator; };

class List { public: /** Constructs an empty list. */ List(); /** Appends an element to the list. @param element the value to append */ List(const List& l);

void push_back(string element); /** Inserts an element into the list. @param iter the position before which to insert @param element the value to insert */ void insert(Iterator iter, string element); /** Removes an element from the list. @param iter the position to remove @return an iterator pointing to the element after the erased element */ Iterator erase(Iterator iter); /** Gets the beginning position of the list. @return an iterator pointing to the beginning of the list */ Iterator begin(); /** Gets the past-the-end position of the list. @return an iterator pointing past the end of the list */ Iterator end(); private: Node* first; Node* last; friend class Iterator; };

class Iterator { public: /** Constructs an iterator that does not point into any list. */ Iterator(); /** Looks up the value at a position. @return the value of the node to which the iterator points */ string get() const; /** Advances the iterator to the next node. */ void next(); /** Moves the iterator to the previous node. */ void previous(); /** Compares two iterators. @param other the iterator to compare with this iterator @return true if this iterator and other are equal */ bool equals(Iterator other) const; private: Node* position; List* container; friend class List; };

#endif

/***************************************************************End of Header *******************************************************/

//Classes:

#include #include #include "list.h" using namespace std;

Node::Node(string element) { data = element; previous = nullptr; next = nullptr; }

List::List() { first = nullptr; last = nullptr; }

void List::push_back(string element) { Node* new_node = new Node(element); if (last == nullptr) // List is empty { first = new_node; last = new_node; } else { new_node->previous = last; last->next = new_node; last = new_node; } }

void List::insert(Iterator iter, string element) { if (iter.position == nullptr) { push_back(element); return; }

Node* after = iter.position; Node* before = after->previous; Node* new_node = new Node(element); new_node->previous = before; new_node->next = after; after->previous = new_node; if (before == nullptr) // Insert at beginning { first = new_node; } else { before->next = new_node; } }

Iterator List::erase(Iterator iter) { Node* remove = iter.position; Node* before = remove->previous; Node* after = remove->next; if (remove == first) { first = after; } else { before->next = after; } if (remove == last) { last = before; } else { after->previous = before; } delete remove; Iterator r; r.position = after; r.container = this; return r; }

Iterator List::begin() { Iterator iter; iter.position = first; iter.container = this; return iter; }

Iterator List::end() { Iterator iter; iter.position = nullptr; iter.container = this; return iter; }

Iterator::Iterator() { position = nullptr; container = nullptr; }

string Iterator::get() const { return position->data; }

void Iterator::next() { position = position->next; }

void Iterator::previous() { if (position == nullptr) { position = container->last; } else { position = position->previous; } }

bool Iterator::equals(Iterator other) const { return position == other.position; }

/* ******************************************************* End of Classes*********************************************************************************************************** */

//Test File:

#include #include #include "list.h" using namespace std;

int main() { List names; names.push_back("Tom"); names.push_back("Diana"); names.push_back("Harry"); names.push_back("Juliet"); // Add a value in fourth place Iterator pos = names.begin(); pos.next(); pos.next(); pos.next(); names.insert(pos, "Romeo"); // Remove the value in second place pos = names.begin(); pos.next(); names.erase(pos); // Print all values for (pos = names.begin(); !pos.equals(names.end()); pos.next()) { cout << pos.get() << endl; } cout << endl; List names_copy(names); //Copy constructor names_copy.push_back("Shakespeare"); // Verify that Shakespeare was inserted. cout << "Printing new list" << endl; for (pos = names_copy.begin(); !pos.equals(names.end()); pos.next()) { cout << pos.get() << endl; // } cout << "Printing original list " << endl; for (pos = names.begin(); !pos.equals(names.end()); pos.next()) { cout << pos.get() << endl; } return 0; }