org.apache.flink.table.sinks.TableSinkBase Maven / Gradle / Ivy

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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.apache.flink.table.sinks;

import org.apache.flink.annotation.Internal;
import org.apache.flink.api.common.typeinfo.TypeInformation;

import java.util.Optional;

/**
 * Base class for {@link TableSink}.
 *
 * @param  The return type of the {@link TableSinkBase}.
 */
@Internal
public abstract class TableSinkBase implements TableSink {

    private Optional fieldNames;
    private Optional[]> fieldTypes;

    /** Returns a deep copy of the {@link TableSink}. */
    protected abstract TableSinkBase copy();

    /** Returns the field names of the table to emit. */
    @Override
    public String[] getFieldNames() {
        if (fieldNames.isPresent()) {
            return fieldNames.get();
        } else {
            throw new IllegalStateException(
                    "Table sink must be configured to retrieve field names.");
        }
    }

    /** Returns the field types of the table to emit. */
    @Override
    public TypeInformation[] getFieldTypes() {
        if (fieldTypes.isPresent()) {
            return fieldTypes.get();
        } else {
            throw new IllegalStateException(
                    "Table sink must be configured to retrieve field types.");
        }
    }

    /**
     * Returns a copy of this {@link TableSink} configured with the field names and types of the
     * table to emit.
     *
     * @param fieldNames The field names of the table to emit.
     * @param fieldTypes The field types of the table to emit.
     * @return A copy of this {@link TableSink} configured with the field names and types of the
     *     table to emit.
     */
    @Override
    public final TableSink configure(String[] fieldNames, TypeInformation[] fieldTypes) {

        final TableSinkBase configuredSink = this.copy();
        configuredSink.fieldNames = Optional.of(fieldNames);
        configuredSink.fieldTypes = Optional.of(fieldTypes);

        return configuredSink;
    }
}