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com.facebook.presto.elasticsearch.decoders.ArrayDecoder Maven / Gradle / Ivy

/*
 * 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 com.facebook.presto.elasticsearch.decoders;

import com.facebook.presto.common.block.BlockBuilder;
import com.facebook.presto.spi.PrestoException;
import org.elasticsearch.search.SearchHit;

import java.util.List;
import java.util.function.Supplier;

import static com.facebook.presto.elasticsearch.ElasticsearchErrorCode.ELASTICSEARCH_TYPE_MISMATCH;
import static java.lang.String.format;
import static java.util.Objects.requireNonNull;

public class ArrayDecoder
        implements Decoder
{
    private final String path;
    private final Decoder elementDecoder;

    public ArrayDecoder(String path, Decoder elementDecoder)
    {
        this.path = requireNonNull(path, "path is null");
        this.elementDecoder = elementDecoder;
    }

    @Override
    public void decode(SearchHit hit, Supplier getter, BlockBuilder output)
    {
        Object data = getter.get();

        if (data == null) {
            output.appendNull();
        }
        else if (data instanceof List) {
            BlockBuilder array = output.beginBlockEntry();
            ((List) data).forEach(element -> elementDecoder.decode(hit, () -> element, array));
            output.closeEntry();
        }
        else {
            throw new PrestoException(ELASTICSEARCH_TYPE_MISMATCH, format("Expected list of elements for field '%s' of type ARRAY: %s [%s]", path, data, data.getClass().getSimpleName()));
        }
    }
}