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public class CursorLinkedList<T> {

private static class Node<T> {

T element;

int next;

Node(T element, int next) {

this.element = element;

this.next = next;

}

boolean isEmpty() {

return element == null;

}

}

private final int os;

private int head;

private final Node<T>[] cursorSpace;

private int count;

private final static int CURSOR_SPACE_SIZE = 100;

{

// init at loading time

cursorSpace = new Node[CURSOR_SPACE_SIZE];

for (int i = 0; i < CURSOR_SPACE_SIZE; i++) {

cursorSpace[i] = new Node<>(null, i + 1);

}

cursorSpace[CURSOR_SPACE_SIZE - 1].next = 0;

}

public CursorLinkedList() {

os = 0;

count = 0;

head = -1;

}

public void printList() {

if (head != -1) {

int start = head;

while (start != -1) {

T element = cursorSpace[start].element;

System.out.println(element.toString());

start = cursorSpace[start].next;

}

}

}

/**

* @return the logical index of the element within the list , not the actual

* index of the [cursorSpace] array

*/

public int indexOf(T element) {

Objects.requireNonNull(element);

Node<T> iterator = cursorSpace[head];

for (int i = 0; i < count; i++) {

if (iterator.element.equals(element)) {

return i;

}

iterator = cursorSpace[iterator.next];

}

return -1;

}

/**

* @param position , the logical index of the element , not the actual one

* within the [cursorSpace] array .

* this method should be used to get the index give by indexOf() method.

* @return

*/

public T get(int position) {

if (position >= 0 && position < count) {

int start = head;

int counter = 0;

while (start != -1) {

T element = cursorSpace[start].element;

if (counter == position){

return element;

}

start = cursorSpace[start].next;

counter++;

}

}

return null;

}

public void removeByIndex(int index){

if(index >= 0 && index < count){

T element = get(index);

remove(element);

}

}

public void remove(T element) {

Objects.requireNonNull(element);

// case element is in the head

T temp_element = cursorSpace[head].element;

int temp_next = cursorSpace[head].next;

if (temp_element.equals(element)) {

free(head);

head = temp_next;

} else { // otherwise cases

int prev_index = head;

int current_index = cursorSpace[prev_index].next;

while (current_index != -1 ) {

T current_element = cursorSpace[current_index].element;

if(current_element.equals(element)){

cursorSpace[prev_index].next = cursorSpace[current_index].next;

free(current_index);

break;

}

prev_index = current_index;

current_index = cursorSpace[prev_index].next;

}

}

count--;

}

private void free(int index) {

Node os_node = cursorSpace[os];

int os_next = os_node.next;

cursorSpace[os].next = index;

cursorSpace[index].element = null;

cursorSpace[index].next = os_next;

}

public void append(T element) {

Objects.requireNonNull(element);

int availableIndex = alloc();

cursorSpace[availableIndex].element = element;

if (head == -1) {

head = availableIndex;

}

int iterator = head;

while (cursorSpace[iterator].next != -1) {

iterator = cursorSpace[iterator].next;

}

cursorSpace[iterator].next = availableIndex;

cursorSpace[availableIndex].next = -1;

count++;

}

/**

* @return the index of the next available node

*/

private int alloc() {

//1- get the index at which the os is pointing

int availableNodeIndex = cursorSpace[os].next;

if (availableNodeIndex == 0) {

throw new OutOfMemoryError();

}

//2- make the os point to the next of the @var{availableNodeIndex}

int availableNext = cursorSpace[availableNodeIndex].next;

cursorSpace[os].next = availableNext;

// this to indicate an end of the list , helpful at testing since any err

// would throw an outOfBoundException

cursorSpace[availableNodeIndex].next = -1;

return availableNodeIndex;

}

}