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Asynchronous PostgreSQL Java driver

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/*
 * 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.impl.io;

import com.github.pgasync.impl.message.DataRow;

import java.nio.ByteBuffer;

/**
 * See PostgreSQL message formats
 *
 *  * 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.
 * 
 *
 * @author Antti Laisi
 */
public class DataRowDecoder implements Decoder {

    @Override
    public byte getMessageId() {
        return 'D';
    }

    @Override
    public DataRow read(ByteBuffer buffer) {
        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);
    }

}