content: /*
   * 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.calcite.adapter.enumerable;
  
  import org.apache.calcite.linq4j.tree.Expression;
  
  import java.util.List;
  
  /**
   * Information for a call to
   * {@link AggImplementor#implementReset(AggContext, AggResetContext)}.
   *
   * <p>{@link AggResetContext} provides access to the accumulator variables
   * that should be reset.
   */
  public interface AggResetContext extends NestedBlockBuilder {
    /**
     * Returns accumulator variables that should be reset.
     * There MUST be an assignment even if you just assign the default value.
     *
     * @return accumulator variables that should be reset or empty list when no
     *   accumulator variables are used by the aggregate implementation.
     *
     * @see AggImplementor#getStateType(org.apache.calcite.adapter.enumerable.AggContext)
     */
    List<Expression> accumulator();
  }
  