[C++] Klasa lista pojedynczo wiązana

#ifndef LISTA_H
#define LISTA_H

#include <string>

using namespace std;

class Lista
{
private:
    class Node
    {
        friend class Lista;
    private:
        string text;
        Node *next;

        Node(string newString)
        {
            text = newString;
            next = NULL;
        }
    };
    Node *head;
    int length;

public:
    Lista();
    Lista(string newString);
    Lista(const Lista&);
    ~Lista();


    void pushBack(string newString);
    void pushFront(string newString);
    void popBack();
    void popFront();
    int indexOf(string textToFind);
    int getLength();
    string getElementOfIndex(int index);
    void showAll();

};

#endif










#include "lista.h"
#include <string>
#include <iostream>

using namespace std;

Lista::Lista()
{
    length = 0;
    head = NULL;
}


Lista::Lista(string newString)
{
    head = new Node(newString);
    length = 1;
}

Lista::Lista(const Lista &lis)
{
    this->length = 0;
    this->head = NULL;
    Node *pointer = lis.head;
    while (pointer != NULL)
    {
        this->pushBack(pointer->text);
        pointer = pointer->next;
    }
}

Lista::~Lista()
{
    while (length > 0) popFront();
}


void Lista::pushBack(string newString)
{
    if (Lista::head == NULL)
    {
        head = new Node(newString);
        length++;
    }
    else
    {
        Node *pointer = head;
        while (pointer->next != NULL)
        {
            pointer = pointer->next;
        }
        (pointer->next) = new Node(newString);
        length++;
    }
}


void Lista::pushFront(string newString)
{
    if (Lista::head == NULL)
    {
        head = new Node(newString);
        length++;
    }
    else
    {
        Node *pointer = new Node(newString);
        pointer->next = head;
        head = pointer;
        length++;
    }
}



void Lista::popBack()
{
    if (head != NULL)
    {
        if (head->next == NULL)
        {
            delete head;
            head = NULL;
            length--;
        }
        else
        {
            Node *pointerLast = head;
            Node *pointerBefore = pointerLast;
            while (pointerLast->next != NULL)
            {
                pointerBefore = pointerLast;
                pointerLast = pointerLast->next;
            }
            pointerBefore->next = NULL;
            delete pointerLast;
            length--;
        }
    }
}


void Lista::popFront()
{
    if (head != NULL)
    {
        Node *pointer = head->next;
        delete head;
        head = pointer;
        length--;
    }
}

int Lista::getLength()
{
    return length;
}

string Lista::getElementOfIndex(int index)
{
    if ( (index >= 0) && (index < length) )
    {
        Node *pointer = head;
        for (int i = 0; i < index; i++)
        {
            pointer = pointer->next;
        }
        return (pointer->text);
    }
    else return "Wrong Index!!!!!!!!!!!!!!!!!!!!!!";
}

int Lista::indexOf(string textToFind)
{
    if (length == 0) return -1;
    else
    {
        Node *pointer = head;
        int i = -1;
        while (pointer != NULL)
        {
            i++;
            if ( (pointer->text).compare(textToFind) == 0 )
            {
                return i;
            }
            pointer = pointer->next;
        }
        return -1;
    }
}


void Lista::showAll()
{
    Node *pointer = head;
    while (pointer != NULL)
    {
        cout << pointer->text << endl;
        pointer = pointer->next;
    }
}