/*
 * 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.phoenix.expression.aggregator;

import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.BaseTerminalExpression;
import org.apache.phoenix.expression.visitor.ExpressionVisitor;
import org.apache.phoenix.schema.SortOrder;
import org.apache.phoenix.util.SizedUtil;

import org.apache.phoenix.thirdparty.com.google.common.base.Preconditions;

/**
 * Base class for Aggregator implementations
 * @since 0.1
 */
public abstract class BaseAggregator extends BaseTerminalExpression implements Aggregator {

  protected final SortOrder sortOrder;

  public BaseAggregator(SortOrder sortOrder) {
    Preconditions.checkNotNull(sortOrder);
    this.sortOrder = sortOrder;
  }

  @Override
  public boolean isNullable() {
    return true;
  }

  @Override
  public int getSize() {
    return SizedUtil.OBJECT_SIZE;
  }

  ImmutableBytesWritable evalClientAggs(Aggregator clientAgg) {
    CountAggregator ca = (CountAggregator) clientAgg;
    ImmutableBytesWritable ptr = new ImmutableBytesWritable();
    ca.evaluate(null, ptr);
    return ptr;
  }

  @Override
  public <T> T accept(ExpressionVisitor<T> visitor) {
    return null;
  }

  @Override
  public boolean trackSize() {
    return false;
  }
}
