/*
 * 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.
 */

/* $Id$ */

package org.apache.fop.fo;

import java.util.NoSuchElementException;

/**
 * Class providing an iterator for zero characters. Used by the Block FO.
 */
public class NullCharIterator extends CharIterator {

    private static CharIterator instance;

    /**
     * Obtain the singleton instance of the null character iterator.
     * @return the char iterator
     */
    public static CharIterator getInstance() {
        if (instance == null) {
            instance = new NullCharIterator();
        }
        return instance;
    }

    /**
     * Constructor
     */
    public NullCharIterator() {
        //nop
    }

    /** {@inheritDoc} */
    public boolean hasNext() {
        return false;
    }

    /** {@inheritDoc} */
    public char nextChar() throws NoSuchElementException {
        throw new NoSuchElementException();
    }

}