/*
 * 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
 *
 *  https://www.apache.org/licenses/LICENSE-2.0
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 * 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
 * Apache-2.0 license and offer limited warranties, support, maintenance, and
 * commercial database integrations.
 *
 * For more information, please visit: https://www.jooq.org/legal/licensing
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package org.jooq;

import java.util.function.Function;

import org.jetbrains.annotations.Nullable;

/**
 * A <code>RecordMapper</code> is a mapper that can receive {@link Record}
 * objects, when fetching data from the database, transforming them into a
 * custom type <code>&lt;E&gt;</code>.
 * <p>
 * <code>RecordMapper</code> is used behind the scenes in methods like
 * {@link ResultQuery#fetchInto(Class)}, {@link Result#into(Class)},
 * {@link Record#into(Class)} and other methods called <code>into(Class)</code>,
 * where the argument class is a <code>Class</code> of type <code>E</code>.
 * <p>
 * The default <code>RecordMapper</code> behaviour in the context of a
 * {@link Configuration} can be overridden through that
 * <code>configuration</code>'s {@link Configuration#recordMapperProvider()}
 * SPI. Custom record mappers can be constructed using lambda expressions, using
 * various {@link Records#mapping(Function1)},
 * {@link Records#mapping(Function2)}, etc. utilities, and other ways.
 * <p>
 * A {@link RecordMapper} is never asked to map <code>null</code> record values,
 * which can be obtained using methods like
 * {@link ResultQuery#fetchOne(RecordMapper)}, or by using {@link RowN} types as
 * nested records in scalar subqueries, mapping them e.g. via
 * {@link Row2#mapping(Function2)}. Instead, <code>null</code> is produced
 * without passing by this SPI.
 * <p>
 * The inverse operation is modelled by {@link RecordUnmapper}.
 *
 * @author Lukas Eder
 */
@FunctionalInterface
public interface RecordMapper<R extends Record, E> extends Function<R, E> {

    /**
     * Map a record into a POJO.
     *
     * @param record The record to be mapped. This is never null.
     * @return The mapped value, which may be <code>null</code> in some
     *         implementations.
     */
    @Nullable
    E map(R record);

    @Override
    default E apply(R record) {
        return map(record);
    }
}
