/*
* Copyright (c) 2003 The Visigoth Software Society. 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 acknowledgement:
* "This product includes software developed by the
* Visigoth Software Society (http://www.visigoths.org/)."
* Alternately, this acknowledgement may appear in the software itself,
* if and wherever such third-party acknowledgements normally appear.
*
* 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
* project contributors may be used to endorse or promote products derived
* from this software without prior written permission. For written
* permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
* nor may "FreeMarker" or "Visigoth" appear in their names
* without prior written permission of the Visigoth Software Society.
*
* 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 VISIGOTH SOFTWARE SOCIETY 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 Visigoth Software Society. For more
* information on the Visigoth Software Society, please see
* http://www.visigoths.org/
*/
package freemarker.ext.beans;
import java.util.Enumeration;
import java.util.NoSuchElementException;
import freemarker.template.TemplateCollectionModel;
import freemarker.template.TemplateModel;
import freemarker.template.TemplateModelException;
import freemarker.template.TemplateModelIterator;
/**
* <p>A class that adds {@link TemplateModelIterator} functionality to the
* {@link Enumeration} interface implementers.
* </p> <p>Using the model as a collection model is NOT thread-safe, as
* enumerations are inherently not thread-safe.
* Further, you can iterate over it only once. Attempts to call the
* {@link #iterator()} method after it was already driven to the end once will
* throw an exception.</p>
* @author Attila Szegedi
* @version $Id: EnumerationModel.java,v 1.24 2003/06/03 13:21:32 szegedia Exp $
*/
public class EnumerationModel
extends
BeanModel
implements
TemplateModelIterator,
TemplateCollectionModel
{
private boolean accessed = false;
/**
* Creates a new model that wraps the specified enumeration object.
* @param enumeration the enumeration object to wrap into a model.
* @param wrapper the {@link BeansWrapper} associated with this model.
* Every model has to have an associated {@link BeansWrapper} instance. The
* model gains many attributes from its wrapper, including the caching
* behavior, method exposure level, method-over-item shadowing policy etc.
*/
public EnumerationModel(Enumeration enumeration, BeansWrapper wrapper)
{
super(enumeration, wrapper);
}
/**
* This allows the enumeration to be used in a <tt><foreach></tt> block.
* @return "this"
*/
public TemplateModelIterator iterator() throws TemplateModelException
{
synchronized(this) {
if(accessed) {
throw new TemplateModelException(
"This collection is stateful and can not be iterated over the" +
" second time.");
}
accessed = true;
}
return this;
}
/**
* Calls underlying {@link Enumeration#nextElement()}.
*/
public boolean hasNext() {
return ((Enumeration)object).hasMoreElements();
}
/**
* Calls underlying {@link Enumeration#nextElement()} and wraps the result.
*/
public TemplateModel next()
throws
TemplateModelException
{
try {
return wrap(((Enumeration)object).nextElement());
}
catch(NoSuchElementException e) {
throw new TemplateModelException(
"No more elements in the enumeration.");
}
}
/**
* Returns {@link Enumeration#hasMoreElements()}. Therefore, an
* enumeration that has no more element evaluates to false, and an
* enumeration that has further elements evaluates to true.
*/
public boolean getAsBoolean() {
return hasNext();
}
}
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