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.plan.Convention;
  import org.apache.calcite.plan.RelTraitSet;
  import org.apache.calcite.rel.RelCollations;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.convert.ConverterRule;
  import org.apache.calcite.rel.core.Aggregate;
  import org.apache.calcite.rel.logical.LogicalAggregate;
  import org.apache.calcite.util.ImmutableIntList;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /**
   * Rule to convert a {@link LogicalAggregate} to an {@link EnumerableSortedAggregate}.
   * You may provide a custom config to convert other nodes that extend {@link Aggregate}.
   *
   * @see EnumerableRules#ENUMERABLE_SORTED_AGGREGATE_RULE
   */
  class EnumerableSortedAggregateRule extends ConverterRule {
    /** Default configuration. */
    public static final Config DEFAULT_CONFIG = Config.INSTANCE
        .withConversion(LogicalAggregate.class, Convention.NONE,
            EnumerableConvention.INSTANCE, "EnumerableSortedAggregateRule")
        .withRuleFactory(EnumerableSortedAggregateRule::new);
  
    /** Called from the Config. */
    protected EnumerableSortedAggregateRule(Config config) {
      super(config);
    }
  
    @Override public @Nullable RelNode convert(RelNode rel) {
      final Aggregate agg = (Aggregate) rel;
      if (!Aggregate.isSimple(agg)) {
        return null;
      }
      final RelTraitSet inputTraits = rel.getCluster()
          .traitSet().replace(EnumerableConvention.INSTANCE)
          .replace(
              RelCollations.of(
                  ImmutableIntList.copyOf(
              agg.getGroupSet().asList())));
      final RelTraitSet selfTraits =
          inputTraits.replace(
              RelCollations.of(
                  ImmutableIntList.identity(agg.getGroupSet().cardinality())));
      return new EnumerableSortedAggregate(
          rel.getCluster(),
          selfTraits,
          convert(agg.getInput(), inputTraits),
          agg.getGroupSet(),
          agg.getGroupSets(),
          agg.getAggCallList());
    }
  }
  