fiore@0: /*  
fiore@0:  CCmI Diagram Editor for Android 
fiore@0:   
fiore@0:  Copyright (C) 2012  Queen Mary University of London (http://ccmi.eecs.qmul.ac.uk/)
fiore@0: 
fiore@0:  This program is free software: you can redistribute it and/or modify
fiore@0:  it under the terms of the GNU General Public License as published by
fiore@0:  the Free Software Foundation, either version 3 of the License, or
fiore@0:  (at your option) any later version.
fiore@0: 
fiore@0:  This program is distributed in the hope that it will be useful,
fiore@0:  but WITHOUT ANY WARRANTY; without even the implied warranty of
fiore@0:  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
fiore@0:  GNU General Public License for more details.
fiore@0: 
fiore@0:  You should have received a copy of the GNU General Public License
fiore@0:  along with this program.  If not, see <http://www.gnu.org/licenses/>.
fiore@0: */
fiore@0: package uk.ac.qmul.eecs.ccmi.utilities;
fiore@0: 
fiore@0: import java.util.ArrayList;
fiore@0: 
fiore@0: /**
fiore@0:  * 
fiore@0:  * The stack is an {@code ArrayList} with a simplified interface for pushing and popping elements 
fiore@0:  * on and from the top 
fiore@0:  *
fiore@0:  * @param <T> The type of objects contained in this stack
fiore@0:  */
fiore@0: public class Stack<T> extends ArrayList<T> {
fiore@0: 	
fiore@0: 	/**
fiore@0: 	 * Create a stack with an initial capacity of {@code size}
fiore@0: 	 *  
fiore@0: 	 * @param size the initial capacity 
fiore@0: 	 */
fiore@0: 	public Stack(int size){
fiore@0: 		super(size);
fiore@0: 	}
fiore@0: 	
fiore@0: 	/**
fiore@0: 	 * Returns the size of the stack 
fiore@0: 	 * 
fiore@0: 	 * @return the size of the stack
fiore@0: 	 */
fiore@0: 	@Override
fiore@0: 	public int size(){
fiore@0: 		return super.size();
fiore@0: 	}
fiore@0: 	
fiore@0: 	/**
fiore@0: 	 * Return the index of the top element for the stack 
fiore@0: 	 * 
fiore@0: 	 * @return index of the top element for the stack or -1 if the stack is empty
fiore@0: 	 */
fiore@0: 	public int level(){
fiore@0: 		return size()-1;
fiore@0: 	}
fiore@0: 	
fiore@0: 	/**
fiore@0: 	 * Adds a new element at the top of the stack. Like in an {@code ArrayList}, 
fiore@0: 	 * the same object can be inserted more than once in the stack
fiore@0: 	 * 
fiore@0: 	 * @param n the new element to add
fiore@0: 	 */
fiore@0: 	public void push(T n){
fiore@0: 		add(n);
fiore@0: 	}
fiore@0: 	
fiore@0: 	/**
fiore@0: 	 * Removes the top element of the stack
fiore@0: 	 * 
fiore@0: 	 * @return the removed element or {@code null} if the stack is empty 
fiore@0: 	 */ 
fiore@0: 	public T pop(){
fiore@0: 		if(size() == 0)
fiore@0: 			return null;
fiore@0: 		return remove(size()-1);
fiore@0: 	}
fiore@0: 	
fiore@0: 	/**
fiore@0: 	 * Returns a reference to the top element of the stack, the element is not removed 
fiore@0: 	 * 
fiore@0: 	 * @return the top element of the stack 
fiore@0: 	 */
fiore@0: 	public T current(){
fiore@0: 		if(size() == 0)
fiore@0: 			return null;
fiore@0: 		return get(size()-1);
fiore@0: 	}
fiore@0: 	
fiore@0: 	private static final long serialVersionUID = 1L;
fiore@0: }