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.RelOptRuleOperand;
  import org.apache.calcite.plan.RelOptUtil;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.core.Project;
  import org.apache.calcite.rel.logical.LogicalJoin;
  import org.apache.calcite.rel.logical.LogicalProject;
  import org.apache.calcite.tools.RelBuilderFactory;
  
  import org.immutables.value.Value;
  
  /**
   * MultiJoinProjectTransposeRule implements the rule for pulling
   * {@link org.apache.calcite.rel.logical.LogicalProject}s that are on top of a
   * {@link MultiJoin} and beneath a
   * {@link org.apache.calcite.rel.logical.LogicalJoin} so the
   * {@link org.apache.calcite.rel.logical.LogicalProject} appears above the
   * {@link org.apache.calcite.rel.logical.LogicalJoin}.
   *
   * <p>In the process of doing
   * so, also save away information about the respective fields that are
   * referenced in the expressions in the
   * {@link org.apache.calcite.rel.logical.LogicalProject} we're pulling up, as
   * well as the join condition, in the resultant {@link MultiJoin}s
   *
   * <p>For example, if we have the following sub-query:
   *
   * <blockquote><pre>{@code
   *   (select X.x1, Y.y1
   *    from X, Y
   *    where X.x2 = Y.y2 and X.x3 = 1 and Y.y3 = 2)}</pre></blockquote>
   *
   * <p>The {@link MultiJoin} associated with (X, Y) associates x1 with X and
   * y1 with Y. Although x3 and y3 need to be read due to the filters, they are
   * not required after the row scan has completed and therefore are not saved.
   * The join fields, x2 and y2, are also tracked separately.
   *
   * <p>Note that by only pulling up projects that are on top of
   * {@link MultiJoin}s, we preserve projections on top of row scans.
   *
   * <p>See the superclass for details on restrictions regarding which
   * {@link org.apache.calcite.rel.logical.LogicalProject}s cannot be pulled.
   *
   * @see CoreRules#MULTI_JOIN_BOTH_PROJECT
   * @see CoreRules#MULTI_JOIN_LEFT_PROJECT
   * @see CoreRules#MULTI_JOIN_RIGHT_PROJECT
   */
  @Value.Enclosing
  public class MultiJoinProjectTransposeRule extends JoinProjectTransposeRule {
  
    /** Creates a MultiJoinProjectTransposeRule. */
    protected MultiJoinProjectTransposeRule(Config config) {
      super(config);
    }
  
    @Deprecated // to be removed before 2.0
    public MultiJoinProjectTransposeRule(
        RelOptRuleOperand operand,
        String description) {
      this(ImmutableMultiJoinProjectTransposeRule.Config.of().withDescription(description)
          .withOperandSupplier(b -> b.exactly(operand)));
    }
  
    @Deprecated // to be removed before 2.0
    public MultiJoinProjectTransposeRule(
        RelOptRuleOperand operand,
        RelBuilderFactory relBuilderFactory,
        String description) {
      this(ImmutableMultiJoinProjectTransposeRule.Config.of().withDescription(description)
          .withRelBuilderFactory(relBuilderFactory)
          .withOperandSupplier(b -> b.exactly(operand)));
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override protected boolean hasLeftChild(RelOptRuleCall call) {
      return call.rels.length != 4;
    }
  
    @Override protected boolean hasRightChild(RelOptRuleCall call) {
      return call.rels.length > 3;
    }
  
    @Override protected Project getRightChild(RelOptRuleCall call) {
      if (call.rels.length == 4) {
        return call.rel(2);
      } else {
        return call.rel(3);
      }
    }
  
    @Override protected RelNode getProjectChild(
        RelOptRuleCall call,
        Project project,
        boolean leftChild) {
      // locate the appropriate MultiJoin based on which rule was fired
      // and which projection we're dealing with
      MultiJoin multiJoin;
      if (leftChild) {
        multiJoin = call.rel(2);
      } else if (call.rels.length == 4) {
        multiJoin = call.rel(3);
      } else {
        multiJoin = call.rel(4);
      }
  
      // create a new MultiJoin that reflects the columns in the projection
      // above the MultiJoin
      return RelOptUtil.projectMultiJoin(multiJoin, project);
    }
  
    /** Rule configuration. */
    @Value.Immutable
    @SuppressWarnings("immutables:subtype")
    public interface Config extends JoinProjectTransposeRule.Config {
      Config BOTH_PROJECT = ImmutableMultiJoinProjectTransposeRule.Config.of()
          .withOperandSupplier(b0 ->
              b0.operand(LogicalJoin.class).inputs(
                  b1 -> b1.operand(LogicalProject.class).oneInput(b2 ->
                      b2.operand(MultiJoin.class).anyInputs()),
                  b3 -> b3.operand(LogicalProject.class).oneInput(b4 ->
                      b4.operand(MultiJoin.class).anyInputs())))
          .withDescription(
              "MultiJoinProjectTransposeRule: with two LogicalProject children");
  
      Config LEFT_PROJECT = ImmutableMultiJoinProjectTransposeRule.Config.of()
          .withOperandSupplier(b0 ->
              b0.operand(LogicalJoin.class).inputs(b1 ->
                  b1.operand(LogicalProject.class).oneInput(b2 ->
                      b2.operand(MultiJoin.class).anyInputs())))
          .withDescription(
              "MultiJoinProjectTransposeRule: with LogicalProject on left");
  
      Config RIGHT_PROJECT = ImmutableMultiJoinProjectTransposeRule.Config.of()
          .withOperandSupplier(b0 ->
              b0.operand(LogicalJoin.class).inputs(
                  b1 -> b1.operand(RelNode.class).anyInputs(),
                  b2 -> b2.operand(LogicalProject.class).oneInput(b3 ->
                      b3.operand(MultiJoin.class).anyInputs())))
          .withDescription(
              "MultiJoinProjectTransposeRule: with LogicalProject on right");
  
  
      @Override default MultiJoinProjectTransposeRule toRule() {
        return new MultiJoinProjectTransposeRule(this);
      }
    }
  }
  