src/main/java/org/apache/sling/query/impl/iterator/AdaptToIterator.java

/*-
 * 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.query.impl.iterator;

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

import org.apache.sling.api.adapter.Adaptable;

public class AdaptToIterator<F, T> implements Iterator<T> {

    private final Iterator<F> iterator;

    private final Class<? extends T> clazz;

    private T currentModel;

    public AdaptToIterator(Iterator<F> iterator, Class<? extends T> clazz) {
        this.clazz = clazz;
        this.iterator = iterator;
    }

    @Override
    public boolean hasNext() {
        if (currentModel == null) {
            getCurrentModel();
        }
        return currentModel != null;
    }

    @Override
    public T next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        T model = currentModel;
        currentModel = null;
        return model;
    }

    public void getCurrentModel() {
        while (iterator.hasNext()) {
            F element = iterator.next();
            if (element instanceof Adaptable) {
                currentModel = ((Adaptable) element).adaptTo(clazz);
            }
            if (currentModel != null) {
                break;
            }
        }
    }

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

}