UniqueMerge.java

/**
 *  Copyright 2007-2008 University Of Southern California
 *
 *  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 edu.isi.pegasus.planner.namespace.aggregator;

import java.util.HashSet;
import java.util.Set;

/**
 * Merges profile as a delimiter separated list. It ensures that only unique values
 * are merged.
 *
 *
 * @author Karan Vahi
 * @version $Revision$
 */
public class UniqueMerge extends Abstract{

    /**
     * Default delimiter
     */
    public static final String DEFAULT_DELIMITER = "@";
    
    private Set<String> mKeys;
    
    public UniqueMerge(){
    }
    
    
    /**
     * Sums up the values.
     *
     * @param oldValue   the existing value for the profile.
     * @param newValue   the new value being added to the profile.
     * @param dflt       the default value to be used in case the values
     *                   are not of the correct type.
     *
     * @return the computed value as a String.
     */
    public String compute( String oldValue, String newValue, String dflt  ){
        StringBuilder sb = new StringBuilder();
    
        if( oldValue == null ){
            mKeys = new HashSet();
            mKeys.add( newValue );
            sb.append( newValue);
            return sb.toString();
        }
        else{
            sb.append( oldValue );
            if( !mKeys.contains( newValue) ){
                //only add we have not previously merged this value
                sb.append( DEFAULT_DELIMITER );
                sb.append( newValue );
            }
            
        }
        
        return sb.toString();
    }


}