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.beam.sdk.extensions.sql.impl.rule;
  
  import org.apache.beam.sdk.extensions.sql.impl.rel.BeamJoinRel;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.plan.RelOptRuleCall;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.core.Join;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.core.RelFactories;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.rules.JoinAssociateRule;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.tools.RelBuilderFactory;
  
  /**
   * This is very similar to {@link
   * org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.rules.JoinAssociateRule}. It only
   * checks if the resulting condition is supported before transforming.
   */
  public class BeamJoinAssociateRule extends JoinAssociateRule {
  
    public static final org.apache.beam.sdk.extensions.sql.impl.rule.BeamJoinAssociateRule INSTANCE =
        new org.apache.beam.sdk.extensions.sql.impl.rule.BeamJoinAssociateRule(
            RelFactories.LOGICAL_BUILDER);
  
    private BeamJoinAssociateRule(RelBuilderFactory relBuilderFactory) {
      super(relBuilderFactory);
    }
  
    @Override
    public void onMatch(final RelOptRuleCall call) {
      super.onMatch(
          new JoinRelOptRuleCall(
              call,
              rel -> {
                Join topJoin = (Join) rel;
                Join bottomJoin = (Join) ((Join) rel).getRight();
                return BeamJoinRel.isJoinLegal(topJoin) && BeamJoinRel.isJoinLegal(bottomJoin);
              }));
    }
  }
  