/*
* Copyright (c) 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 David Berkman
*
* This file is part of the SmallMind Code Project.
*
* The SmallMind Code Project is free software, you can redistribute
* it and/or modify it under either, at your discretion...
*
* 1) The terms of GNU Affero General Public License as published by the
* Free Software Foundation, either version 3 of the License, or (at
* your option) any later version.
*
* ...or...
*
* 2) The terms of the Apache License, Version 2.0.
*
* The SmallMind Code Project is distributed in the hope that it will
* be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License or Apache License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* and the Apache License along with the SmallMind Code Project. If not, see
* <http://www.gnu.org/licenses/> or <http://www.apache.org/licenses/LICENSE-2.0>.
*
* Additional permission under the GNU Affero GPL version 3 section 7
* ------------------------------------------------------------------
* If you modify this Program, or any covered work, by linking or
* combining it with other code, such other code is not for that reason
* alone subject to any of the requirements of the GNU Affero GPL
* version 3.
*/
package org.smallmind.nutsnbolts.context;
import java.util.LinkedList;
import java.util.List;
public class ContextStack<C extends Context> {
private final LinkedList<C> contextList;
public ContextStack () {
contextList = new LinkedList<C>();
}
public ContextStack (ContextStack<C> contextStack) {
contextList = new LinkedList<>(contextStack.getInternalList());
}
private List<C> getInternalList () {
return contextList;
}
public synchronized boolean isEmpty () {
return contextList.isEmpty();
}
public synchronized C peek () {
if (contextList.isEmpty()) {
return null;
}
return contextList.getFirst();
}
public synchronized void push (C context) {
if (context instanceof LifecycleAware) {
((LifecycleAware)context).beforePush();
}
contextList.addFirst(context);
}
public synchronized C pop () {
if (!contextList.isEmpty()) {
C context = contextList.removeFirst();
if (context instanceof LifecycleAware) {
((LifecycleAware)context).afterPop();
}
return context;
}
return null;
}
}