org.gradoop.model.impl.functions.epgm.PropertyGetter.java Source code

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Here is the source code for org.gradoop.model.impl.functions.epgm.PropertyGetter.java

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/*
 * This file is part of Gradoop.
 *
 * Gradoop is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Gradoop is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Gradoop. If not, see <http://www.gnu.org/licenses/>.
 */

package org.gradoop.model.impl.functions.epgm;

import com.google.common.collect.Lists;
import org.gradoop.model.api.EPGMElement;
import org.gradoop.model.api.functions.UnaryFunction;
import org.gradoop.model.impl.properties.PropertyValue;

import java.util.List;

import static com.google.common.base.Preconditions.checkNotNull;

/**
 * Extracts a list of {@link PropertyValue} instances from a given entity using
 * a list of property keys. The order of the property keys determines the order
 * of the values in the result. If the EPGM element does not have a property,
 * the property value will be {@code PropertyValue.NULL_VALUE}.
 *
 * @param <EL> EPGM element
 */
public class PropertyGetter<EL extends EPGMElement> implements UnaryFunction<EL, List<PropertyValue>> {

    /**
     * Property keys to retrieve property values
     */
    private final List<String> propertyKeys;

    /**
     * Constructor
     *
     * @param propertyKeys property keys to retrieve values for
     */
    public PropertyGetter(List<String> propertyKeys) {
        this.propertyKeys = checkNotNull(propertyKeys);
    }

    @Override
    public List<PropertyValue> execute(EL entity) throws Exception {
        List<PropertyValue> propertyValueList = Lists.newArrayListWithCapacity(propertyKeys.size());

        for (String propertyKey : propertyKeys) {
            if (entity.hasProperty(propertyKey)) {
                propertyValueList.add(entity.getPropertyValue(propertyKey));
            } else {
                propertyValueList.add(PropertyValue.NULL_VALUE);
            }
        }
        return propertyValueList;
    }
}