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.rex.RexNode;
  import org.apache.calcite.util.ImmutableIntList;
  
  import com.google.common.collect.ImmutableList;
  
  import java.util.Set;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Base class for any join whose condition is based on column equality.
   *
   * <p>For most of the cases, {@link JoinInfo#isEqui()} can already decide
   * if the join condition is based on column equality.
   *
   * <p>{@code EquiJoin} is an abstract class for inheritance of Calcite enumerable
   * joins and join implementation of other system. You should inherit the {@code EquiJoin}
   * if your join implementation does not support non-equi join conditions. Calcite would
   * eliminate some optimize logic for {@code EquiJoin} in some planning rules.
   * e.g. {@link org.apache.calcite.rel.rules.FilterJoinRule} would not push non-equi
   * join conditions of the above filter into the join underneath if it is an {@code EquiJoin}.
   *
   * @deprecated This class is no longer needed; if you are writing a sub-class of
   * Join that only accepts equi conditions, it is sufficient that it extends
   * {@link Join}. It will be evident that it is an equi-join when its
   * {@link JoinInfo#nonEquiConditions} is an empty list.
   */
  @Deprecated // to be removed before 2.0
  public abstract class EquiJoin extends Join {
    public final ImmutableIntList leftKeys;
    public final ImmutableIntList rightKeys;
  
    /** Creates an EquiJoin. */
    protected EquiJoin(RelOptCluster cluster, RelTraitSet traits, RelNode left,
        RelNode right, RexNode condition, Set<CorrelationId> variablesSet,
        JoinRelType joinType) {
      super(cluster, traits, ImmutableList.of(), left, right, condition, variablesSet, joinType);
      this.leftKeys = requireNonNull(joinInfo.leftKeys);
      this.rightKeys = requireNonNull(joinInfo.rightKeys);
      assert joinInfo.isEqui() : "Create EquiJoin with non-equi join condition.";
    }
  
    /** Creates an EquiJoin. */
    @Deprecated // to be removed before 2.0
    protected EquiJoin(RelOptCluster cluster, RelTraitSet traits, RelNode left,
        RelNode right, RexNode condition, ImmutableIntList leftKeys,
        ImmutableIntList rightKeys, Set<CorrelationId> variablesSet,
        JoinRelType joinType) {
      super(cluster, traits, ImmutableList.of(), left, right, condition, variablesSet, joinType);
      this.leftKeys = requireNonNull(leftKeys, "leftKeys");
      this.rightKeys = requireNonNull(rightKeys, "rightKeys");
    }
  
    @Deprecated // to be removed before 2.0
    protected EquiJoin(RelOptCluster cluster, RelTraitSet traits, RelNode left,
            RelNode right, RexNode condition, ImmutableIntList leftKeys,
            ImmutableIntList rightKeys, JoinRelType joinType,
            Set<String> variablesStopped) {
      this(cluster, traits, left, right, condition, leftKeys, rightKeys,
          CorrelationId.setOf(variablesStopped), joinType);
    }
  
    public ImmutableIntList getLeftKeys() {
      return leftKeys;
    }
  
    public ImmutableIntList getRightKeys() {
      return rightKeys;
    }
  }
  