parquet.thrift.projection.amend.DefaultProtocolEventsGenerator Maven / Gradle / Ivy

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/**
 * Copyright 2012 Twitter, Inc.
 *
 * 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 parquet.thrift.projection.amend;

import org.apache.thrift.TException;
import org.apache.thrift.protocol.TField;
import org.apache.thrift.protocol.TProtocol;
import org.apache.thrift.protocol.TType;
import parquet.thrift.ParquetProtocol;
import parquet.thrift.struct.ThriftField;

import java.util.ArrayList;
import java.util.List;

/**
 * Generate events for Parquet Protocol for a Thrift Field. The generated events are used for default values
 * when required fields are missing.
 * {@link ProtocolEventsAmender} will use this class to generate events for missing required fields
 */
class DefaultProtocolEventsGenerator {
  public static ParquetProtocol READ_FIELD_STOP = new ParquetProtocol("readFieldBegin() => STOP") {
    final TField stop = new TField("", TType.STOP, (short) 0);

    @Override
    public TField readFieldBegin() throws TException {
      return stop;
    }
  };
  public static ParquetProtocol READ_STRUCT_END = new ParquetProtocol("readStructEnd()") {
    @Override
    public void readStructEnd() throws TException {
    }
  };
  public static ParquetProtocol READ_FIELD_END = new ParquetProtocol("readFieldEnd()") {
    @Override
    public void readFieldEnd() throws TException {
    }
  };
  List createdEvents = new ArrayList();

  public List createProtocolEventsForField(ThriftField missingField) {
    TProtocol fieldBegin = new ReadFieldBeginProtocol(missingField);
    createdEvents.add(fieldBegin);

    DefaultEventsVisitor dummyCreatorvisitor = new DefaultEventsVisitor();
    missingField.getType().accept(dummyCreatorvisitor);
    createdEvents.addAll(dummyCreatorvisitor.getEvents());
    createdEvents.add(READ_FIELD_END);
    return createdEvents;
  }

}