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.Filter;
  import org.apache.calcite.rel.core.Sort;
  import org.apache.calcite.rex.RexNode;
  import org.apache.calcite.tools.RelBuilder;
  
  import org.immutables.value.Value;
  
  /**
   * Rule that transforms a {@link Filter} on top of a {@link Sort}
   * into a {@link Sort} on top of a {@link Filter}.
   */
  @Value.Enclosing
  public class FilterSortTransposeRule
      extends RelRule<FilterSortTransposeRule.Config>
      implements TransformationRule {
    protected FilterSortTransposeRule(FilterSortTransposeRule.Config config) {
      super(config);
    }
  
    @Override public void onMatch(RelOptRuleCall call) {
      final Filter filter = call.rel(0);
      final Sort sort = call.rel(1);
  
      final RelBuilder builder = call.builder();
      final RexNode condition = filter.getCondition();
      RelNode newSort = builder.push(sort.getInput())
          .filter(condition)
          .sort(sort.getCollation())
          .build();
  
      call.transformTo(newSort);
    }
  
    /** Rule configuration. */
    @Value.Immutable
    public interface Config extends RelRule.Config {
      Config DEFAULT = ImmutableFilterSortTransposeRule.Config.of()
          .withOperandSupplier(f ->
              f.operand(Filter.class)
                  .oneInput(s ->
                      s.operand(Sort.class)
                          .predicate(RelOptUtil::isPureOrder)
                          .anyInputs()));
  
      @Override default FilterSortTransposeRule toRule() {
        return new FilterSortTransposeRule(this);
      }
    }
  }
  