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JDBC Driver for the Firebird RDBMS
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/*
 * $Id$
 *
 * Public Firebird Java API.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *    1. Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *    2. Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *    3. The name of the author may not be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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 */
package org.firebirdsql.gds.ng.fields;

import java.sql.SQLException;

/**
 * Interface for calculating the blr (binary language representation) of a row.
 *
 * @author Mark Rotteveel
 * @since 3.0
 */
public interface BlrCalculator {

    /**
     * Calculates the blr for the row descriptor.
     *
     * @param rowDescriptor
     *         Row descriptor
     * @return Byte array with the blr
     * @throws SQLException
     *         When the {@link RowDescriptor} contains an unsupported field type.
     */
    byte[] calculateBlr(RowDescriptor rowDescriptor) throws SQLException;

    /**
     * Calculates the blr for a specific row value.
     * 
     * This allows to optimize for the actual length of the field.
     * 
     *
     * @param rowDescriptor
     *         Row descriptor
     * @param rowValue
     *         Row value
     * @return Byte array with the blr
     * @throws SQLException
     *         When the {@link RowValue} contains an unsupported field type.
     */
    byte[] calculateBlr(RowDescriptor rowDescriptor, RowValue rowValue) throws SQLException;

    /**
     * Calculates the io length for the field descriptor.
     * 
     * The return value indicates the length and padding of the type in the buffer
     * 

     * < 0 : Type is of specified length * -1 and not padded
     * == 0 : Type is of dynamic length (which is specified in the buffer as an integer) and padded
     * > 0 : Type is of specified length minus 1 (subtracting 1 is required to avoid 0 for types of zero length) and padded
     * 
     * 
     *
     * @param fieldDescriptor
     *         Field descriptor
     * @return The io length
     */
    public int calculateIoLength(FieldDescriptor fieldDescriptor) throws SQLException;

    /**
     * Calculates the io length for the field descriptor.
     * 
     * The return value indicates the length and padding of the type in the buffer
     * 

     * < 0 : Type is of specified length * -1 and not padded
     * == 0 : Type is of dynamic length (which is specified in the buffer as an integer) and padded
     * > 0 : Type is of specified length minus 1 (subtracting 1 is required to avoid 0 for types of zero length)
     * nd padded
     * 
     * 
     * 
     * This allows to optimize for the actual length of the field.
     * 
     * 
     * For CHAR ({@link org.firebirdsql.gds.ISCConstants#SQL_TEXT} the implementation should be consistent
     * with the lengths as given by {@link #calculateBlr(RowDescriptor, RowValue)}.
     * 
     *
     * @param fieldDescriptor
     *         Field descriptor
     * @param fieldValue
     *         Field value
     * @return The io length
     */
    public int calculateIoLength(FieldDescriptor fieldDescriptor, FieldValue fieldValue) throws SQLException;
}