ColumnMapperFactory.java

/*
 * 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 org.jdbi.v3.core.mapper;

import java.lang.reflect.Type;
import java.util.Optional;

import org.jdbi.v3.core.config.ConfigRegistry;

/**
 * Factory interface used to produce column mappers.
 */
@FunctionalInterface
public interface ColumnMapperFactory {
    /**
     * Supplies a column mapper which will map columns to type if the factory supports it; empty otherwise.
     *
     * @param type   the target type to map to
     * @param config the config registry, for composition
     * @return a column mapper for the given type if this factory supports it, or <code>Optional.empty()</code> otherwise.
     * @see ColumnMappers for composition
     */
    Optional<ColumnMapper<?>> build(Type type, ConfigRegistry config);

    /**
     * Create a ColumnMapperFactory from a given {@link ColumnMapper} that
     * matches a single Type exactly.
     *
     * @param type the type to match with equals.
     * @param mapper the mapper to return
     * @return the factory
     */
    static ColumnMapperFactory of(Type type, ColumnMapper<?> mapper) {
        return (t, c) -> t.equals(type) ? Optional.of(mapper) : Optional.empty();
    }
}