com.intelligentsia.dowsers.entity.view.SplitterAttribute.java Source code

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Here is the source code for com.intelligentsia.dowsers.entity.view.SplitterAttribute.java

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/**
 *        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 com.intelligentsia.dowsers.entity.view;

import java.util.List;

import org.intelligentsia.keystone.kernel.api.StringUtils;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.intelligentsia.dowsers.entity.view.processor.Item;

/**
 * SplitterAttribute implement an attribute based splitter. The specified
 * attribute should be {@link Iterable}. If attribute value is null, list will
 * be empty (depends on empty flag).
 * 
 * @author <a href="mailto:jguibert@intelligents-ia.com" >Jerome Guibert</a>
 */
public class SplitterAttribute implements Splitter {

    private final String attributeName;

    private final boolean ignoreEmpty;

    /**
     * Build a new instance of SplitterAttribute. if attribute value is empty
     * then the result list will be empty.
     * 
     * @param attributeName
     *            attribute Name
     */
    public SplitterAttribute(final String attributeName) {
        this(attributeName, true);
    }

    /**
     * Build a new instance of SplitterAttribute.
     * 
     * @param attributeName
     *            attribute Name
     * @param ignoreEmpty
     *            if true and attribute value is empty then the result list will
     *            be empty. Either, a list with a single item will be returned.
     */
    public SplitterAttribute(final String attributeName, final boolean ignoreEmpty) {
        this.attributeName = Preconditions.checkNotNull(attributeName);
        this.ignoreEmpty = ignoreEmpty;
    }

    @Override
    public List<Item> apply(final Item input) {
        final List<Item> items = Lists.newArrayList();

        final Object object = input.get(attributeName);
        if (object != null) {
            if (!Iterable.class.isAssignableFrom(object.getClass())) {
                throw new IllegalStateException(
                        StringUtils.format("Attribute %s did not implements Iterable interface", attributeName));
            }
            final Iterable<?> iterable = (Iterable<?>) object;
            for (final Object thing : iterable) {
                final Item item = input.dump();
                item.put(attributeName, thing);
                items.add(item);
            }
        } else {
            if (!ignoreEmpty) {
                items.add(input);
            }
        }
        return items;
    }

}