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.RelRule;
  import org.apache.calcite.rel.core.Calc;
  import org.apache.calcite.rel.core.Filter;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.tools.RelBuilder;
  import org.apache.calcite.tools.RelBuilderFactory;
  import org.apache.calcite.util.Pair;
  
  import com.google.common.collect.ImmutableList;
  
  import org.immutables.value.Value;
  
  /**
   * Planner rule that converts a {@link Calc}
   * to a {@link org.apache.calcite.rel.core.Project}
   * and {@link Filter}.
   *
   * <p>Not enabled by default, as it works against the usual flow, which is to
   * convert {@code Project} and {@code Filter} to {@code Calc}. But useful for
   * specific tasks, such as optimizing before calling an
   * {@link org.apache.calcite.interpreter.Interpreter}.
   *
   * @see CoreRules#CALC_SPLIT
   */
  @Value.Enclosing
  public class CalcSplitRule extends RelRule<CalcSplitRule.Config>
      implements TransformationRule {
  
    /** Creates a CalcSplitRule. */
    protected CalcSplitRule(Config config) {
      super(config);
    }
  
    @Deprecated // to be removed before 2.0
    public CalcSplitRule(RelBuilderFactory relBuilderFactory) {
      this(Config.DEFAULT.withRelBuilderFactory(relBuilderFactory)
          .as(Config.class));
    }
  
    @Override public void onMatch(RelOptRuleCall call) {
      final Calc calc = call.rel(0);
      final Pair<ImmutableList<RexNode>, ImmutableList<RexNode>> projectFilter =
          calc.getProgram().split();
      final RelBuilder relBuilder = call.builder();
      relBuilder.push(calc.getInput());
      relBuilder.filter(projectFilter.right);
      relBuilder.project(projectFilter.left, calc.getRowType().getFieldNames());
      call.transformTo(relBuilder.build());
    }
  
    /** Rule configuration. */
    @Value.Immutable
    public interface Config extends RelRule.Config {
      Config DEFAULT = ImmutableCalcSplitRule.Config.of()
          .withOperandSupplier(b -> b.operand(Calc.class).anyInputs());
  
      @Override default CalcSplitRule toRule() {
        return new CalcSplitRule(this);
      }
    }
  }
  