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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

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;

/**
 * 

A class that adds {@link TemplateModelIterator} functionality to the * {@link Enumeration} interface implementers. *

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.

*/ 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 <#list> block. * @return "this" */ @Override 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()}. */ @Override public boolean hasNext() { return ((Enumeration) object).hasMoreElements(); } /** * Calls underlying {@link Enumeration#nextElement()} and wraps the result. */ @Override 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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