/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Ant", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */
package org.apache.tools.ant.taskdefs.optional.junit;

import java.util.Enumeration;
import java.util.NoSuchElementException;

/**
 * A couple of methods related to enumerations that might be useful.
 * This class should probably disappear once the required JDK is set to 1.2
 * instead of 1.1.
 *
 * @author <a href="mailto:sbailliez@imediation.com">Stephane Bailliez</a>
 */
public final class Enumerations {
	
	private Enumerations(){
	}

	/**
	 * creates an enumeration from an array of objects.
	 * @param	array	the array of object to enumerate.
	 * @return the enumeration over the array of objects.
	 */
	public static Enumeration fromArray(Object[] array){
		return new ArrayEnumeration(array);
	}

	/**
	* creates an enumeration from an array of enumeration. The created enumeration
	* will sequentially enumerate over all elements of each enumeration and skip
	* <tt>null</tt> enumeration elements in the array.
	* @param	enums	the array of enumerations.
	* @return the enumeration over the array of enumerations.
	 */
	public static Enumeration fromCompound(Enumeration[] enums){
		return new CompoundEnumeration(enums);
	}

}


/**
 * Convenient enumeration over an array of objects.
 * @author <a href="mailto:sbailliez@imediation.com">Stephane Bailliez</a>
 */
class ArrayEnumeration implements Enumeration {
	
	/** object array */
	private Object[] array;
	
	/** current index */
	private int pos;
	
	/**
	 * Initialize a new enumeration that wraps an array.
	 * @param	array	the array of object to enumerate.
	 */
	public ArrayEnumeration(Object[] array){
		this.array = array;
		this.pos = 0;
	}
	/**
	 * Tests if this enumeration contains more elements.
	 *
	 * @return  <code>true</code> if and only if this enumeration object
	 *           contains at least one more element to provide;
	 *          <code>false</code> otherwise.
	 */
	public boolean hasMoreElements() {
		return (pos < array.length);
	}

	/**
	 * Returns the next element of this enumeration if this enumeration
	 * object has at least one more element to provide.
	 *
	 * @return     the next element of this enumeration.
	 * @throws  NoSuchElementException  if no more elements exist.
	 */
	public Object nextElement() throws NoSuchElementException {
		if (hasMoreElements()) {
			Object o = array[pos];
			pos++;
			return o;
		}
		throw new NoSuchElementException();
	}
}
/**
 * Convenient enumeration over an array of enumeration. For example:
 * <pre>
 * Enumeration e1 = v1.elements();
 * while (e1.hasMoreElements()){
 *    // do something
 * }
 * Enumeration e2 = v2.elements();
 * while (e2.hasMoreElements()){
 *    // do the same thing
 * }
 * </pre>
 * can be written as:
 * <pre>
 * Enumeration[] enums = { v1.elements(), v2.elements() };
 * Enumeration e = Enumerations.fromCompound(enums);
 * while (e.hasMoreElements()){
 *    // do something
 * }
 * </pre>
 * Note that the enumeration will skip null elements in the array. The following is
 * thus possible:
 * <pre>
 * Enumeration[] enums = { v1.elements(), null, v2.elements() }; // a null enumeration in the array
 * Enumeration e = Enumerations.fromCompound(enums);
 * while (e.hasMoreElements()){
 *    // do something
 * }
 * </pre>
 * @author <a href="mailto:sbailliez@imediation.com">Stephane Bailliez</a>
 */
 class CompoundEnumeration implements Enumeration {
	
	/** enumeration array */
	private Enumeration[] enumArray;
	
	/** index in the enums array */
	private int index = 0;

    public CompoundEnumeration(Enumeration[] enumarray) {
		this.enumArray = enumarray;
    }

	/**
	 * Tests if this enumeration contains more elements.
	 *
	 * @return  <code>true</code> if and only if this enumeration object
	 *           contains at least one more element to provide;
	 *          <code>false</code> otherwise.
	 */
    public boolean hasMoreElements() {
		while (index < enumArray.length) {
			if (enumArray[index] != null && enumArray[index].hasMoreElements()) {
				return true;
			}
			index++;
		}
		return false;
    }

	/**
	 * Returns the next element of this enumeration if this enumeration
	 * object has at least one more element to provide.
	 *
	 * @return     the next element of this enumeration.
	 * @throws  NoSuchElementException  if no more elements exist.
	 */
    public Object nextElement() throws NoSuchElementException {
		if ( hasMoreElements() ) {
			return enumArray[index].nextElement();
		}
		throw new NoSuchElementException();
    }
}