/*
 * 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 org.apache.sling.resourceresolver.impl.helper;

import java.util.Iterator;
import java.util.NoSuchElementException;

public abstract class AbstractIterator<T> implements Iterator<T> {

    private T nextElement;

    protected abstract T seek();

    @Override
    public boolean hasNext() {
        if (nextElement == null) {
            nextElement = seek();
        }
        return nextElement != null;
    }

    @Override
    public T next() {
        if (nextElement == null && !hasNext()) {
            throw new NoSuchElementException();
        }
        final T result = nextElement;
        nextElement = null;
        return result;
    }

    @Override
    public void remove() {
        throw new UnsupportedOperationException();
    }

}