Decode.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.tajo.engine.function.string;

import org.apache.commons.codec.binary.Base64;
import org.apache.commons.lang.StringEscapeUtils;
import org.apache.tajo.catalog.Column;
import org.apache.tajo.common.TajoDataTypes;
import org.apache.tajo.datum.Datum;
import org.apache.tajo.datum.DatumFactory;
import org.apache.tajo.datum.NullDatum;
import org.apache.tajo.engine.function.GeneralFunction;
import org.apache.tajo.engine.function.annotation.Description;
import org.apache.tajo.engine.function.annotation.ParamTypes;
import org.apache.tajo.storage.Tuple;


/**
 * Function definition
 *
 * bytearray decode(string text, format text)
 */
@Description(
  functionName = "decode",
  description = "Decode binary data from textual representation in string. "
          + "Options for format are same as in encode.",
  detail = "format is one of 'base64', 'hex'",
  example = "> SELECT decode('MTIzAAE=', 'base64');\n"
          + "\\x3132330001",
  returnType = TajoDataTypes.Type.TEXT,
  paramTypes = {@ParamTypes(paramTypes = {TajoDataTypes.Type.TEXT, TajoDataTypes.Type.TEXT})}
)
public class Decode extends GeneralFunction {
  public Decode() {
    super(new Column[] {
        new Column("string", TajoDataTypes.Type.TEXT),
        new Column("format", TajoDataTypes.Type.TEXT)
    });
  }

  @Override
  public Datum eval(Tuple params) {
    Datum datum = params.get(0);
    Datum formatType = params.get(1);
    String decodedBase64Text="";
    String decodedHexString="";

    if(datum instanceof NullDatum) return NullDatum.get();
    if(formatType instanceof NullDatum) return NullDatum.get();

    if(formatType.asChars().toLowerCase().equals("base64")) {
      try {
        // Base64
        decodedBase64Text = new String(Base64.decodeBase64(datum.asChars().getBytes()));
      }
      catch (Exception e) {
        return NullDatum.get();
      }

      return DatumFactory.createText(StringEscapeUtils.escapeJava(decodedBase64Text));
    }
    else if(formatType.asChars().toLowerCase().equals("hex")) {
      try {
        // Hex
        decodedHexString = HexStringConverter.getInstance().decodeHex(datum.asChars());
      }
      catch (Exception e) {
        return NullDatum.get();
      }
      return DatumFactory.createText(StringEscapeUtils.escapeJava(decodedHexString));
    }
    else
      return NullDatum.get();
  }
}