package elte.java2_utikalauz5.generic;

/**
Generikus lista.

@link.forrásfájl {@docRoot}/../data/generic/src LinkedList.java
@since Java 2 Útikalauz programozóknak 5.0
*/
class LinkedList<A> implements Collection<A> {

  protected class Node {
    A elt;
    Node next = null;
    Node(A elt) { this.elt = elt; }
  }

  protected Node head = null;
  protected Node tail = null;

  public void add(A elt) {
    if ( head == null ) { head = new Node(elt); tail = head; }
    else { tail.next = new Node(elt); tail = tail.next; }
  }

  public Iterator<A> iterator() {
    return new Iterator<A>() {
      protected Node ptr = head;
      public boolean hasNext() { return ptr != null; }
      public A next() {
        if ( ptr == null ) throw new NoSuchElementException();
        A elt = ptr.elt; ptr = ptr.next; return elt;
      }
    };
  }

  public static void main(String[] args) {
    LinkedList<Byte> xs = new LinkedList<Byte>();    // byte lista
    xs.add(new Byte("0")); xs.add(new Byte("1"));
    Byte x = xs.iterator().next();
    LinkedList<String> ys = new LinkedList<String>();    // String lista
    ys.add("zero"); ys.add("one");
    String y = ys.iterator().next();
    LinkedList<LinkedList<String>> zs = new LinkedList<LinkedList<String>>();
    zs.add(ys);     // String listák listája
    String z = zs.iterator().next().iterator().next();
  }
}

interface Collection<A> {
  public void add(A x);
  public Iterator<A> iterator();
}
interface Iterator<A> {
  public A next();
  public boolean hasNext();
}
class NoSuchElementException extends RuntimeException {
    /** Verziószám */
    private final static long serialVersionUID = 15L;
}