/tags/release-0.1-rc2/hive/external/ql/src/java/org/apache/hadoop/hive/ql/udf/UDFConcat.java

/**
 * 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 org.apache.hadoop.hive.ql.udf;

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDF;
import org.apache.hadoop.io.Text;

/**
 * UDFConcat.
 *
 */
@Description(name = "concat",
    value = "_FUNC_(str1, str2, ... strN) - returns the concatenation of str1, str2, ... strN",
    extended = "Returns NULL if any argument is NULL.\n"
    + "Example:\n"
    + "  > SELECT _FUNC_('abc', 'def') FROM src LIMIT 1;\n"
    + "  'abcdef'")
public class UDFConcat extends UDF {

  public UDFConcat() {
  }

  private Text text = new Text();

  public Text evaluate(Text... args) {
    text.clear();
    for (Text arg : args) {
      if (arg == null) {
        return null;
      }
      text.append(arg.getBytes(), 0, arg.getLength());
    }
    return text;
  }

}