src/main/java/org/apache/sling/query/impl/function/ParentFunction.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.function;

import java.util.Iterator;

import org.apache.sling.query.api.internal.ElementToIteratorFunction;
import org.apache.sling.query.api.internal.TreeProvider;
import org.apache.sling.query.impl.util.IteratorUtils;

public class ParentFunction<T> implements ElementToIteratorFunction<T> {

    private final TreeProvider<T> provider;

    public ParentFunction(TreeProvider<T> provider) {
        this.provider = provider;
    }

    @Override
    public Iterator<T> apply(T element) {
        T parent = provider.getParent(element);
        if (parent == null) {
            return IteratorUtils.emptyIterator();
        } else {
            return IteratorUtils.singleElementIterator(parent);
        }
    }

}