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Core services for Usergrid system.

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/*******************************************************************************
 * Copyright 2012 Apigee Corporation
 * 
 * Licensed 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.usergrid.persistence;

import static org.usergrid.persistence.cassandra.IndexUpdate.compareIndexedValues;

import java.util.Comparator;

public class EntityPropertyComparator implements Comparator {

	final boolean reverse;
	final String propertyName;

	public EntityPropertyComparator(String propertyName) {
		this.propertyName = propertyName;
		reverse = false;
	}

	public EntityPropertyComparator(String propertyName, boolean reverse) {
		this.propertyName = propertyName;
		this.reverse = reverse;
	}

	@Override
	public int compare(Entity e1, Entity e2) {

		if ((e1 == null) && (e2 == null)) {
			return 0;
		} else if (e1 == null) {
			return -1;
		} else if (e2 == null) {
			return 1;
		}

		int c = compareIndexedValues(e1.getProperty(propertyName),
				e2.getProperty(propertyName));
		if (reverse) {
			c = -c;
		}
		return c;
	}

}