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.RelFactories;
  import org.apache.calcite.rel.core.Union;
  import org.apache.calcite.rel.logical.LogicalUnion;
  import org.apache.calcite.tools.RelBuilder;
  import org.apache.calcite.tools.RelBuilderFactory;
  
  import org.immutables.value.Value;
  
  /**
   * Planner rule that translates a distinct
   * {@link org.apache.calcite.rel.core.Union}
   * (<code>all</code> = <code>false</code>)
   * into an {@link org.apache.calcite.rel.core.Aggregate}
   * on top of a non-distinct {@link org.apache.calcite.rel.core.Union}
   * (<code>all</code> = <code>true</code>).
   *
   * @see CoreRules#UNION_TO_DISTINCT
   */
  @Value.Enclosing
  public class UnionToDistinctRule
      extends RelRule<UnionToDistinctRule.Config>
      implements TransformationRule {
  
    /** Creates a UnionToDistinctRule. */
    protected UnionToDistinctRule(Config config) {
      super(config);
    }
  
    @Deprecated // to be removed before 2.0
    public UnionToDistinctRule(Class<? extends Union> unionClass,
        RelBuilderFactory relBuilderFactory) {
      this(Config.DEFAULT.withOperandFor(unionClass)
          .withRelBuilderFactory(relBuilderFactory)
          .as(Config.class));
    }
  
    @Deprecated // to be removed before 2.0
    public UnionToDistinctRule(Class<? extends Union> unionClazz,
        RelFactories.SetOpFactory setOpFactory) {
      this(Config.DEFAULT.withOperandFor(unionClazz)
          .withRelBuilderFactory(RelBuilder.proto(setOpFactory))
          .as(Config.class));
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public void onMatch(RelOptRuleCall call) {
      final Union union = call.rel(0);
      final RelBuilder relBuilder = call.builder();
      relBuilder.pushAll(union.getInputs());
      relBuilder.union(true, union.getInputs().size());
      relBuilder.distinct();
      call.transformTo(relBuilder.build());
    }
  
    /** Rule configuration. */
    @Value.Immutable
    public interface Config extends RelRule.Config {
      Config DEFAULT = ImmutableUnionToDistinctRule.Config.of()
          .withOperandFor(LogicalUnion.class);
  
      @Override default UnionToDistinctRule toRule() {
        return new UnionToDistinctRule(this);
      }
  
      /** Defines an operand tree for the given classes. */
      default Config withOperandFor(Class<? extends Union> unionClass) {
        return withOperandSupplier(b ->
            b.operand(unionClass)
                .predicate(union -> !union.all).anyInputs())
            .as(Config.class);
      }
    }
  }
  