JoinArrayUDF.java

package brickhouse.udf.collect;
/**
 * Copyright 2012 Klout, Inc
 *
 * 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.
 *
 **/


import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.serde2.objectinspector.ListObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.StringObjectInspector;

import java.util.List;

/**
 * Return a Ruby-like Array join , appending a separator
 * between
 */
public class JoinArrayUDF extends GenericUDF {
    private ListObjectInspector listInspector;
    private StringObjectInspector strInspector;

    public String evaluate(List<Object> strArray, String sep) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < strArray.size(); ++i) {
            StringObjectInspector strInspector = (StringObjectInspector) listInspector.getListElementObjectInspector();
            sb.append(strInspector.getPrimitiveJavaObject(strArray.get(i)));
            if (i < strArray.size() - 1) {
                sb.append(sep);
            }
        }
        return sb.toString();
    }

    @Override
    public Object evaluate(DeferredObject[] arg0) throws HiveException {
        List objList = listInspector.getList(arg0[0].get());
        return evaluate(objList, strInspector.getPrimitiveJavaObject(arg0[1].get()));
    }

    @Override
    public String getDisplayString(String[] arg0) {
        // TODO Auto-generated method stub
        return "join_array()";
    }

    @Override
    public ObjectInspector initialize(ObjectInspector[] arg0)
            throws UDFArgumentException {

        /// TODO  add default separator
        //// TODO  complain about usage ..
        listInspector = (ListObjectInspector) arg0[0];
        strInspector = (StringObjectInspector) arg0[1];


        return PrimitiveObjectInspectorFactory.javaStringObjectInspector;
    }
}