/*
 * 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 TemplateModelIterator functionality to the 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 iterator() method after it was already driven to the end once will throw an exception.
/**
 * <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>
 */

public class EnumerationModel
extends
    BeanModel
implements
    TemplateModelIterator,
    TemplateCollectionModel {
    private boolean accessed = false;
    
    
Creates a new model that wraps the specified enumeration object.
Params:
enumeration – the enumeration object to wrap into a model.
wrapper – the BeansWrapper associated with this model. Every model has to have an associated BeansWrapper instance. The model gains many attributes from its wrapper, including the caching behavior, method exposure level, method-over-item shadowing policy etc./**
     * 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.
Returns:
"this"/**
     * This allows the enumeration to be used in a <tt>&lt;#list&gt;</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 Enumeration.nextElement(). /**
     * Calls underlying {@link Enumeration#nextElement()}.
     */
    public boolean hasNext() {
        return ((Enumeration) object).hasMoreElements();
    }


    
Calls underlying Enumeration.nextElement() and wraps the result. /**
     * 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 Enumeration.hasMoreElements(). Therefore, an enumeration that has no more element evaluates to false, and an enumeration that has further elements evaluates to true. /**
     * 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();
    }
}