exec/java-exec/src/main/java/org/apache/drill/exec/physical/config/TopN.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.config;

import java.util.List;

import org.apache.drill.common.logical.data.Order.Ordering;
import org.apache.drill.exec.physical.base.PhysicalOperator;
import org.apache.drill.exec.physical.base.PhysicalVisitor;
import org.apache.drill.exec.proto.UserBitShared.CoreOperatorType;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonTypeName;

@JsonTypeName("top-n")
public class TopN extends Sort {
  static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(TopN.class);

  private final int limit;

  @JsonCreator
  public TopN(@JsonProperty("child") PhysicalOperator child, @JsonProperty("orderings") List<Ordering> orderings, @JsonProperty("reverse") boolean reverse, @JsonProperty("limit") int limit) {
    super(child, orderings, reverse);
    this.limit = limit;
  }

  @Override
  public List<Ordering> getOrderings() {
    return orderings;
  }

  @Override
  public boolean getReverse() {
    return reverse;
  }

  public int getLimit() {
    return limit;
  }

  @Override
  public <T, X, E extends Throwable> T accept(PhysicalVisitor<T, X, E> physicalVisitor, X value) throws E{
    return physicalVisitor.visitSort(this, value);
  }

  @Override
  protected PhysicalOperator getNewWithChild(PhysicalOperator child) {
    return new TopN(child, orderings, reverse, limit);
  }

  @Override
  public int getOperatorType() {
    return CoreOperatorType.TOP_N_SORT_VALUE;
  }

  @Override
  public String toString() {
    return "TopN[orderings=" + orderings
        + ", reverse=" + reverse
        + ", limit=" + limit
        + "]";
  }
}