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.RelOptCluster;
  import org.apache.calcite.plan.RelOptRuleCall;
  import org.apache.calcite.plan.RelRule;
  import org.apache.calcite.rel.core.Calc;
  import org.apache.calcite.rel.core.Project;
  import org.apache.calcite.rel.logical.LogicalCalc;
  import org.apache.calcite.rel.logical.LogicalProject;
  import org.apache.calcite.rex.RexBuilder;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.rex.RexOver;
  import org.apache.calcite.rex.RexProgram;
  import org.apache.calcite.rex.RexProgramBuilder;
  import org.apache.calcite.rex.RexUtil;
  import org.apache.calcite.tools.RelBuilderFactory;
  import org.apache.calcite.util.Pair;
  
  import org.immutables.value.Value;
  
  /**
   * Planner rule that merges a
   * {@link org.apache.calcite.rel.core.Project} and a
   * {@link org.apache.calcite.rel.core.Calc}.
   *
   * <p>The resulting {@link org.apache.calcite.rel.core.Calc} has the
   * same project list as the original
   * {@link org.apache.calcite.rel.core.Project}, but expressed in terms
   * of the original {@link org.apache.calcite.rel.core.Calc}'s inputs.
   *
   * @see FilterCalcMergeRule
   * @see CoreRules#PROJECT_CALC_MERGE
   */
  @Value.Enclosing
  public class ProjectCalcMergeRule
      extends RelRule<ProjectCalcMergeRule.Config>
      implements TransformationRule {
  
    /** Creates a ProjectCalcMergeRule. */
    protected ProjectCalcMergeRule(Config config) {
      super(config);
    }
  
    @Deprecated // to be removed before 2.0
    public ProjectCalcMergeRule(RelBuilderFactory relBuilderFactory) {
      this(Config.DEFAULT.withRelBuilderFactory(relBuilderFactory)
          .as(Config.class));
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public void onMatch(RelOptRuleCall call) {
      final Project project = call.rel(0);
      final Calc calc = call.rel(1);
  
      // Don't merge a project which contains windowed aggregates onto a
      // calc. That would effectively be pushing a windowed aggregate down
      // through a filter.
      final RelOptCluster cluster = project.getCluster();
      RexProgram program =
          RexProgram.create(
              calc.getRowType(),
              project.getProjects(),
              null,
              project.getRowType(),
              cluster.getRexBuilder());
      if (RexOver.containsOver(program)) {
        return;
      }
  
      // Create a program containing the project node's expressions.
      final RexBuilder rexBuilder = cluster.getRexBuilder();
      final RexProgramBuilder progBuilder =
          new RexProgramBuilder(
              calc.getRowType(),
              rexBuilder);
      for (Pair<RexNode, String> field : project.getNamedProjects()) {
        progBuilder.addProject(field.left, field.right);
      }
      RexProgram topProgram = progBuilder.getProgram();
      RexProgram bottomProgram = calc.getProgram();
  
      // Merge the programs together.
      RexProgram mergedProgram =
          RexProgramBuilder.mergePrograms(
              topProgram,
              bottomProgram,
              rexBuilder);
      final Calc newCalc =
          calc.copy(calc.getTraitSet(), calc.getInput(), mergedProgram);
      call.transformTo(newCalc);
    }
  
    /** Rule configuration. */
    @Value.Immutable
    public interface Config extends RelRule.Config {
      Config DEFAULT = ImmutableProjectCalcMergeRule.Config.of()
          .withOperandFor(LogicalProject.class, LogicalCalc.class);
  
      @Override default ProjectCalcMergeRule toRule() {
        return new ProjectCalcMergeRule(this);
      }
  
      /** Defines an operand tree for the given classes. */
      default Config withOperandFor(Class<? extends Project> projectClass,
          Class<? extends Calc> calcClass) {
        return withOperandSupplier(b0 ->
            b0.operand(projectClass)
                .predicate(project -> !RexUtil.SubQueryFinder.containsSubQuery(project))
                .oneInput(b1 -> b1.operand(calcClass).anyInputs()))
            .as(Config.class);
      }
    }
  }
  