Stack.java :  » Scripting » Pnuts » org » pnuts » util » Java Open Source

/*
 * @(#)Stack.java 1.2 04/12/06
 *
 * Copyright (c) 1997-2003 Sun Microsystems, Inc. All Rights Reserved.
 *
 * See the file "LICENSE.txt" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 */
package org.pnuts.util;

/**
 * Stack implemented by a linked list
 */
public class Stack {
  Cell cell;

  int count = 0;

  public void push(Object object) {
    Cell old = cell;
    cell = new Cell();
    cell.object = object;
    cell.next = old;
    count++;
  }

  public Object pop() {
    Cell c = cell;
    cell = cell.next;
    count--;
    return c.object;
  }

  public int size() {
    return count;
  }

  public Object peek() {
    return cell.object;
  }

  public void removeAllElements() {
    cell = null;
    count = 0;
  }

  public void copyInto(Object[] array) {
    Cell c = cell;
    for (int i = 0; i < count; i++) {
      array[count - 1 - i] = c.object;
      c = c.next;
    }
  }
}