/*
 * Copyright (c) 2010, 2020 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2004 The Apache Software Foundation
 *
 * Licensed 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 org.glassfish.grizzly.http.server.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;

HttpHandler class that wraps an Enumeration around a Java2 collection classes object
Iterator so that existing APIs returning Enumerations can easily run on top of the new collections.
Constructors are provided to easily create such wrappers.
Author:
Craig R. McClanahan
Version:
$Revision: 1.3 $ $Date: 2007/06/18 14:17:08 $/**
 * HttpHandler class that wraps an <code>Enumeration</code> around a Java2 collection classes object
 * <code>Iterator</code> so that existing APIs returning Enumerations can easily run on top of the new collections.
 * Constructors are provided to easily create such wrappers.
 *
 * @author Craig R. McClanahan
 * @version $Revision: 1.3 $ $Date: 2007/06/18 14:17:08 $
 */

public final class Enumerator<E> implements Enumeration<E> {

    // ----------------------------------------------------------- Constructors

    
Return an Enumeration over the values of the specified Collection.
Params:
collection – Collection whose values should be enumerated/**
     * Return an Enumeration over the values of the specified Collection.
     *
     * @param collection Collection whose values should be enumerated
     */
    public Enumerator(Collection<E> collection) {

        this(collection.iterator());

    }

    
Return an Enumeration over the values of the specified Collection.
Params:
collection – Collection whose values should be enumerated
clone – true to clone iterator/**
     * Return an Enumeration over the values of the specified Collection.
     *
     * @param collection Collection whose values should be enumerated
     * @param clone true to clone iterator
     */
    public Enumerator(Collection<E> collection, boolean clone) {

        this(collection.iterator(), clone);

    }

    
Return an Enumeration over the values returned by the specified Iterable. 
Params:
iterable – Iterable to be wrapped/**
     * Return an Enumeration over the values returned by the specified {@link Iterable}.
     *
     * @param iterable {@link Iterable} to be wrapped
     */
    public Enumerator(Iterable<E> iterable) {
        this(iterable.iterator());
    }

    
Return an Enumeration over the values returned by the specified Iterable. 
Params:
iterable – Iterable to be wrapped
clone – true to clone iterator/**
     * Return an Enumeration over the values returned by the specified {@link Iterable}.
     *
     * @param iterable {@link Iterable} to be wrapped
     * @param clone true to clone iterator
     */
    public Enumerator(Iterable<E> iterable, boolean clone) {
        this(iterable.iterator(), clone);
    }

    
Return an Enumeration over the values returned by the specified Iterator.
Params:
iterator – Iterator to be wrapped/**
     * Return an Enumeration over the values returned by the specified Iterator.
     *
     * @param iterator Iterator to be wrapped
     */
    public Enumerator(Iterator<E> iterator) {

        this.iterator = iterator;

    }

    
Return an Enumeration over the values returned by the specified Iterator.
Params:
iterator – Iterator to be wrapped
clone – true to clone iterator/**
     * Return an Enumeration over the values returned by the specified Iterator.
     *
     * @param iterator Iterator to be wrapped
     * @param clone true to clone iterator
     */
    public Enumerator(Iterator<E> iterator, boolean clone) {

        super();
        if (!clone) {
            this.iterator = iterator;
        } else {
            List<E> list = new ArrayList<>();
            while (iterator.hasNext()) {
                list.add(iterator.next());
            }
            this.iterator = list.iterator();
        }

    }

    
Return an Enumeration over the values of the specified Map.
Params:
map – Map whose values should be enumerated/**
     * Return an Enumeration over the values of the specified Map.
     *
     * @param map Map whose values should be enumerated
     */
    public Enumerator(Map<?, E> map) {

        this(map.values().iterator());

    }

    
Return an Enumeration over the values of the specified Map.
Params:
map – Map whose values should be enumerated
clone – true to clone iterator/**
     * Return an Enumeration over the values of the specified Map.
     *
     * @param map Map whose values should be enumerated
     * @param clone true to clone iterator
     */
    public Enumerator(Map<?, E> map, boolean clone) {

        this(map.values().iterator(), clone);

    }

    // ----------------------------------------------------- Instance Variables

    
The Iterator over which the Enumeration represented by this class actually operates.
/**
     * The <code>Iterator</code> over which the <code>Enumeration</code> represented by this class actually operates.
     */
    private Iterator<E> iterator = null;

    // --------------------------------------------------------- Public Methods

    
Tests if this enumeration contains more elements.
Returns:
true if and only if this enumeration object contains at least one more element to provide,
false otherwise/**
     * Tests if this enumeration contains more elements.
     *
     * @return <tt>true</tt> if and only if this enumeration object contains at least one more element to provide,
     * <tt>false</tt> otherwise
     */
    @Override
    public boolean hasMoreElements() {

        return iterator.hasNext();

    }

    
Returns the next element of this enumeration if this enumeration has at least one more element to provide.
Throws:
NoSuchElementException – if no more elements exist
Returns:
the next element of this enumeration/**
     * Returns the next element of this enumeration if this enumeration has at least one more element to provide.
     *
     * @return the next element of this enumeration
     *
     * @exception NoSuchElementException if no more elements exist
     */
    @Override
    public E nextElement() throws NoSuchElementException {

        return iterator.next();

    }

}