/*

  * $Source$

  * $Revision$

  *

  * Copyright (C) 2000 William Chesters

  *

  * Part of Melati (http://melati.org), a framework for the rapid

  * development of clean, maintainable web applications.

  *

  * Melati is free software; Permission is granted to copy, distribute

  * and/or modify this software under the terms either:

  *

  * a) the GNU General Public License as published by the Free Software

  *    Foundation; either version 2 of the License, or (at your option)

  *    any later version,

  *

  *    or

  *

  * b) any version of the Melati Software License, as published

  *    at http://melati.org

  *

  * You should have received a copy of the GNU General Public License and

  * the Melati Software License along with this program;

  * if not, write to the Free Software Foundation, Inc.,

  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA to obtain the

  * GNU General Public License and visit http://melati.org to obtain the

  * Melati Software License.

  *

  * Feel free to contact the Developers of Melati (http://melati.org),

  * if you would like to work out a different arrangement than the options

  * outlined here.  It is our intention to allow Melati to be used by as

  * wide an audience as possible.

  *

  * This program 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 for more details.

  *

  * Contact details for copyright holder:

  *

  *     William Chesters <williamc At paneris.org>

  *     http://paneris.org/~williamc

  *     Obrechtstraat 114, 2517VX Den Haag, The Netherlands

  */

 package org.melati.poem.util;

 import java.util.Enumeration;

 import java.util.NoSuchElementException;

 /**

  * An <code>Enumeration</code> representing the first <code>n</code> 

  * elements of another <code>Enumeration</code>.

  */

 public class LimitedEnumeration<T> implements SkipEnumeration<T>{

   private Enumeration<T> base;

   private int limit;

   private int seen = 0;

   /**

    * Constructor.

    * @param base the underlying Enumeration

    * @param limit the excluded limit

    */

   public LimitedEnumeration(Enumeration<T> base, int limit) {

     this.base = base;

     this.limit = limit;

   }

   /**

    * {@inheritDoc}

    * @see java.util.Enumeration#hasMoreElements()

    */

   public synchronized boolean hasMoreElements() {

     return seen < limit && base.hasMoreElements();

   }

   /**

    * {@inheritDoc}

    * @see java.util.Enumeration#nextElement()

    */

   public synchronized T nextElement() throws NoSuchElementException {

     if (seen >= limit)

       throw new NoSuchElementException();

     T it = base.nextElement();

     ++seen;

     return it;

   }

   /**

    * {@inheritDoc}

    * @see org.melati.poem.util.SkipEnumeration#skip()

    */

   public synchronized void skip() throws NoSuchElementException {

     if (seen >= limit)

       throw new NoSuchElementException();

     if (base instanceof SkipEnumeration)

       ((SkipEnumeration<T>)base).skip();

     else

       base.nextElement();

     ++seen;

   }

 }