exec/java-exec/src/main/java/org/apache/drill/exec/physical/impl/scan/project/ResolvedNullColumn.java

/*
 * 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.drill.exec.physical.impl.scan.project;

import org.apache.drill.common.types.TypeProtos.MajorType;
import org.apache.drill.exec.physical.impl.scan.project.NullColumnLoader.NullColumnSpec;
import org.apache.drill.exec.record.MaterializedField;
import org.apache.drill.exec.record.metadata.ColumnMetadata;

/**
 * Projected column that serves as both a resolved column (provides projection
 * mapping) and a null column spec (provides the information needed to create
 * the required null vectors.)
 */
public class ResolvedNullColumn extends ResolvedColumn implements NullColumnSpec {

  private final String name;
  private MajorType type;
  private String defaultValue;

  public ResolvedNullColumn(String name, MajorType type, String defaultValue,
      VectorSource source, int sourceIndex) {
    super(source, sourceIndex);
    this.name = name;
    this.type = type;
    this.defaultValue = defaultValue;
  }

  public ResolvedNullColumn(ColumnMetadata colDefn,
      VectorSource source, int sourceIndex) {
    super(colDefn, source, sourceIndex);
    this.name = colDefn.name();
    this.type = colDefn.majorType();
    this.defaultValue = colDefn.defaultValue();
  }

  @Override
  public String name() { return name; }

  @Override
  public MajorType type() { return type; }

  @Override
  public void setType(MajorType type) {

    // Adjust the default value if needed.
    if (this.type != null && type.getMinorType() != this.type.getMinorType()) {
      defaultValue = null;
    }

    // Update the actual type based on what the null-column
    // mechanism chose for this column.
    this.type = type;
  }

  @Override
  public MaterializedField schema() {
    return MaterializedField.create(name, type);
  }

  @Override
  public String defaultValue() { return defaultValue; }

  @Override
  public String toString() {
    StringBuilder buf = new StringBuilder();
    buf
      .append("[")
      .append(getClass().getSimpleName())
      .append(" name=")
      .append(name())
      .append("]");
    return buf.toString();
  }
}