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.plan.hep;
  
  import org.apache.calcite.plan.RelHintsPropagator;
  import org.apache.calcite.plan.RelOptPlanner;
  import org.apache.calcite.plan.RelOptRuleCall;
  import org.apache.calcite.plan.RelOptRuleOperand;
  import org.apache.calcite.plan.RelOptUtil;
  import org.apache.calcite.rel.RelNode;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  
  /**
   * HepRuleCall implements {@link RelOptRuleCall} for a {@link HepPlanner}. It
   * remembers transformation results so that the planner can choose which one (if
   * any) should replace the original expression.
   */
  public class HepRuleCall extends RelOptRuleCall {
    //~ Instance fields --------------------------------------------------------
  
    private final List<RelNode> results = new ArrayList<>();
  
    //~ Constructors -----------------------------------------------------------
  
    HepRuleCall(
        RelOptPlanner planner,
        RelOptRuleOperand operand,
        RelNode[] rels,
        Map<RelNode, List<RelNode>> nodeChildren,
        @Nullable List<RelNode> parents) {
      super(planner, operand, rels, nodeChildren, parents);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public void transformTo(RelNode rel, Map<RelNode, RelNode> equiv,
        RelHintsPropagator handler) {
      final RelNode rel0 = rels[0];
      RelOptUtil.verifyTypeEquivalence(rel0, rel, rel0);
      rel = handler.propagate(rel0, rel);
      results.add(rel);
      rel0.getCluster().invalidateMetadataQuery();
    }
  
    List<RelNode> getResults() {
      return results;
    }
  }
  