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.rel.core;
  
  import org.apache.calcite.plan.RelOptCluster;
  import org.apache.calcite.plan.RelTraitSet;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.RelWriter;
  import org.apache.calcite.rel.hint.RelHint;
  import org.apache.calcite.rex.RexNode;
  
  import java.util.List;
  import java.util.Set;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Base class for various ASOF JOIN representations.
   */
  public abstract class AsofJoin extends Join {
    /** Compared to standard joins, ASOF joins have an additional condition for comparing
     * columns that usually contain timestamp values (however, the data type of these columns
     * can be any type that supports comparisons, and is not restricted to be TIMESTAMP).
     */
    protected final RexNode matchCondition;
  
    protected AsofJoin(
        RelOptCluster cluster,
        RelTraitSet traitSet,
        List<RelHint> hints,
        RelNode left,
        RelNode right,
        RexNode condition,
        RexNode matchCondition,
        Set<CorrelationId> variablesSet,
        JoinRelType joinType) {
      super(cluster, traitSet, hints, left, right, condition, variablesSet, joinType);
      this.matchCondition = requireNonNull(matchCondition, "matchCondition");
    }
  
    public RexNode getMatchCondition() {
      return matchCondition;
    }
  
    @Override public RelWriter explainTerms(RelWriter pw) {
      return super.explainTerms(pw)
          .item("matchCondition", matchCondition);
    }
  }
  