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.rules;
  
  import org.apache.calcite.plan.RelOptRuleCall;
  import org.apache.calcite.plan.RelOptUtil;
  import org.apache.calcite.plan.RelRule;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.core.Join;
  import org.apache.calcite.rel.core.RelFactories;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.tools.RelBuilder;
  import org.apache.calcite.tools.RelBuilderFactory;
  
  import org.immutables.value.Value;
  
  /**
   * Planner rule that pushes down expressions in "equal" join condition.
   *
   * <p>For example, given
   * "emp JOIN dept ON emp.deptno + 1 = dept.deptno", adds a project above
   * "emp" that computes the expression
   * "emp.deptno + 1". The resulting join condition is a simple combination
   * of AND, equals, and input fields, plus the remaining non-equal conditions.
   *
   * @see CoreRules#JOIN_PUSH_EXPRESSIONS
   */
  @Value.Enclosing
  public class JoinPushExpressionsRule
      extends RelRule<JoinPushExpressionsRule.Config>
      implements TransformationRule {
  
    /** Creates a JoinPushExpressionsRule. */
    protected JoinPushExpressionsRule(Config config) {
      super(config);
    }
  
    @Deprecated // to be removed before 2.0
    public JoinPushExpressionsRule(Class<? extends Join> joinClass,
        RelBuilderFactory relBuilderFactory) {
      this(Config.DEFAULT.withRelBuilderFactory(relBuilderFactory)
          .as(Config.class)
          .withOperandFor(joinClass));
    }
  
    @Deprecated // to be removed before 2.0
    public JoinPushExpressionsRule(Class<? extends Join> joinClass,
        RelFactories.ProjectFactory projectFactory) {
      this(Config.DEFAULT.withRelBuilderFactory(RelBuilder.proto(projectFactory))
          .as(Config.class)
          .withOperandFor(joinClass));
    }
  
    @Override public void onMatch(RelOptRuleCall call) {
      Join join = call.rel(0);
  
      // Push expression in join condition into Project below Join.
      RelNode newJoin = RelOptUtil.pushDownJoinConditions(join, call.builder());
  
      // If the join is the same, we bail out
      if (newJoin instanceof Join) {
        final RexNode newCondition = ((Join) newJoin).getCondition();
        if (join.getCondition().equals(newCondition)) {
          return;
        }
      }
  
      call.transformTo(newJoin);
    }
  
    /** Rule configuration. */
    @Value.Immutable
    public interface Config extends RelRule.Config {
      Config DEFAULT = ImmutableJoinPushExpressionsRule.Config.of()
          .withOperandFor(Join.class);
  
      @Override default JoinPushExpressionsRule toRule() {
        return new JoinPushExpressionsRule(this);
      }
  
      /** Defines an operand tree for the given classes. */
      default Config withOperandFor(Class<? extends Join> joinClass) {
        return withOperandSupplier(b -> b.operand(joinClass).anyInputs())
            .as(Config.class);
      }
    }
  }
  