EnumerableCombineRule.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.calcite.adapter.enumerable;

import org.apache.calcite.plan.Convention;
import org.apache.calcite.plan.RelTraitSet;
import org.apache.calcite.rel.RelNode;
import org.apache.calcite.rel.convert.ConverterRule;
import org.apache.calcite.rel.core.Combine;
import org.apache.calcite.util.Util;

import java.util.List;

/**
 * Rule to convert a {@link Combine} to an {@link EnumerableCombine}.
 *
 * @see EnumerableRules#ENUMERABLE_COMBINE_RULE
 */
class EnumerableCombineRule extends ConverterRule {
  /** Default configuration. */
  static final Config DEFAULT_CONFIG = Config.INSTANCE
      .withConversion(Combine.class, Convention.NONE,
          EnumerableConvention.INSTANCE, "EnumerableCombineRule")
      .withRuleFactory(EnumerableCombineRule::new);

  /** Called from the Config. */
  protected EnumerableCombineRule(Config config) {
    super(config);
  }

  @Override public RelNode convert(RelNode rel) {
    final Combine combine = (Combine) rel;
    final EnumerableConvention out = EnumerableConvention.INSTANCE;
    final RelTraitSet traitSet = rel.getCluster().traitSet().replace(out);
    final List<RelNode> newInputs =
        Util.transform(combine.getInputs(), n -> convert(n, traitSet));
    return new EnumerableCombine(rel.getCluster(), traitSet, newInputs);
  }
}