content: /*
   * 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 com.github.pgasync.io.backend;
  
  import com.github.pgasync.io.Decoder;
  import com.github.pgasync.message.backend.DataRow;
  
  import java.nio.ByteBuffer;
  import java.nio.charset.Charset;
  
  /**
   * See <a href="www.postgresql.org/docs/9.3/static/protocol-message-formats.html">Postgres message formats</a>
   *
   * <pre>
   * DataRow (B)
   *  Byte1('D')
   *      Identifies the message as a data row.
   *  Int32
   *      Length of message contents in bytes, including self.
   *  Int16
   *      The number of column values that follow (possibly zero).
   *  Next, the following pair of fields appear for each column:
   *  Int32
   *      The length of the column value, in bytes (this count does not include itself). Can be zero. As a special case, -1 indicates a NULL column value. No value bytes follow in the NULL case.
   *  Byten
   *      The value of the column, in the format indicated by the associated format code. n is the above length.
   * </pre>
   *
   * @author Antti Laisi
   */
  public class DataRowDecoder implements Decoder<DataRow> {
  
      @Override
      public byte getMessageId() {
          return 'D';
      }
  
      @Override
      public DataRow read(ByteBuffer buffer, Charset encoding) {
          byte[][] values = new byte[buffer.getShort()][];
          for (int i = 0; i < values.length; i++) {
              int length = buffer.getInt();
              if (length != -1) {
                  values[i] = new byte[length];
                  buffer.get(values[i]);
              } else {
                  values[i] = null;
              }
          }
          return new DataRow(values);
      }
  
  }
  