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/**
 * Copyright (c) 2009-2016, Data Geekery GmbH (http://www.datageekery.com)
 * All rights reserved.
 *
 * 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.
 *
 * Other licenses:
 * -----------------------------------------------------------------------------
 * Commercial licenses for this work are available. These replace the above
 * ASL 2.0 and offer limited warranties, support, maintenance, and commercial
 * database integrations.
 *
 * For more information, please visit: http://www.jooq.org/licenses
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 *
 */
package org.jooq;

import java.io.Serializable;

import org.jooq.impl.SQLDataType;

/**
 * A Converter for data types.
 * 
 * A general data type conversion interface that can be provided to jOOQ at
 * various places in order to perform custom data type conversion. Conversion is
 * directed, this means that the Converter is used
 * 

 * to load database types converting them to user types "FROM" the database.
 * Hence, {@link #fromType()} is the type as defined in the database.
 * to store user types converting them to database types "TO" the database.
 * Hence, {@link #toType()} is the user-defined type
 * 
 * 
 * Note: In order to avoid unwanted side-effects, it is highly recommended (yet
 * not required) for {@link #from(Object)} and {@link #to(Object)} to be
 * reciprocal. The two methods are reciprocal, if for all
 * X and Y, it can be said that
 * 

 * if Y.equals(converter.from(X)), then
 * X.equals(converter.to(Y)).
 * 
 * X.equals(converter.from(converter.to(X)))
 * X.equals(converter.to(converter.from(X)))
 * 
 * 
 * Furthermore, it is recommended (yet not required) that
 * 

 * converter.from(null) == null
 * converter.to(null) == null
 * 
 *
 * @author Lukas Eder
 * @param  The database type - i.e. any type available from
 *            {@link SQLDataType}
 * @param  The user type
 */
public interface Converter extends Serializable {

    /**
     * Convert a database object to a user object
     *
     * @param databaseObject The database object
     * @return The user object
     */
    U from(T databaseObject);

    /**
     * Convert a user object to a database object
     *
     * @param userObject The user object
     * @return The database object
     */
    T to(U userObject);

    /**
     * The database type
     */
    Class fromType();

    /**
     * The user type
     */
    Class toType();
}