/*

  * Licensed to the Apache Software Foundation (ASF) under one

  * or more contributor license agreements. See the NOTICE file

  * distributed with this work for additional information

  * regarding copyright ownership. The ASF licenses this file

  * to you under the Apache License, Version 2.0 (the

  * "License"); you may not use this file except in compliance

  * with the License. You may obtain a copy of the License at

  *

  * http://www.apache.org/licenses/LICENSE-2.0

  *

  * Unless required by applicable law or agreed to in writing,

  * software distributed under the License is distributed on an

  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

  * KIND, either express or implied. See the License for the

  * specific language governing permissions and limitations

  * under the License.

  */

 package org.apache.johnzon.core;

 class SimpleStack<T> {

     private Element<T> head;

     void push(final T element) {

         final Element<T> tmp = new Element<T>();

         tmp.payload = element;

         tmp.previous = head;

         head = tmp;

     }

     T pop() {

         final T tmp = head.payload;

         head = head.previous;

         return tmp;

     }

     T peek() {

         return head.payload;

     }

     boolean isEmpty() {

         return head == null;

     }

     private static class Element<T> {

         public Element() {

         }

         Element<T> previous;

         T payload;

     }

 }