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.adapter.enumerable;
  
  import org.apache.calcite.linq4j.function.Experimental;
  import org.apache.calcite.linq4j.function.Function0;
  import org.apache.calcite.linq4j.tree.BlockBuilder;
  import org.apache.calcite.linq4j.tree.Expression;
  import org.apache.calcite.linq4j.tree.Expressions;
  import org.apache.calcite.plan.RelOptCluster;
  import org.apache.calcite.plan.RelOptTable;
  import org.apache.calcite.plan.RelTraitSet;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.core.RepeatUnion;
  import org.apache.calcite.schema.TransientTable;
  import org.apache.calcite.util.BuiltInMethod;
  import org.apache.calcite.util.Util;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.List;
  
  import static org.apache.calcite.util.Util.last;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Implementation of {@link RepeatUnion} in
   * {@link EnumerableConvention enumerable calling convention}.
   *
   * <p>NOTE: The current API is experimental and subject to change without
   * notice.
   */
  @Experimental
  public class EnumerableRepeatUnion extends RepeatUnion implements EnumerableRel {
  
    /**
     * Creates an EnumerableRepeatUnion.
     */
    EnumerableRepeatUnion(RelOptCluster cluster, RelTraitSet traitSet,
        RelNode seed, RelNode iterative, boolean all, int iterationLimit,
        @Nullable RelOptTable transientTable) {
      super(cluster, traitSet, seed, iterative, all, iterationLimit, transientTable);
    }
  
    @Override public EnumerableRepeatUnion copy(RelTraitSet traitSet, List<RelNode> inputs) {
      assert inputs.size() == 2;
      return new EnumerableRepeatUnion(getCluster(), traitSet,
          inputs.get(0), inputs.get(1), all, iterationLimit, transientTable);
    }
  
    @Override public Result implement(EnumerableRelImplementor implementor, Prefer pref) {
  
      // return repeatUnion(<seedExp>, <iterativeExp>, iterationLimit, all, <comparer>);
  
      BlockBuilder builder = new BlockBuilder();
      RelNode seed = getSeedRel();
      RelNode iteration = getIterativeRel();
  
      Expression cleanUpFunctionExp = Expressions.constant(null);
      if (transientTable != null) {
        // root.getRootSchema().add(tableName, table);
        Expression tableExp =
            implementor.stash(
                requireNonNull(transientTable.unwrap(TransientTable.class)),
                TransientTable.class);
        String tableName = last(transientTable.getQualifiedName());
        Expression tableNameExp = Expressions.constant(tableName, String.class);
        builder.append(
            Expressions.call(
                Expressions.call(
                    implementor.getRootExpression(),
                    BuiltInMethod.DATA_CONTEXT_GET_ROOT_SCHEMA.method),
                BuiltInMethod.SCHEMA_PLUS_ADD_TABLE.method,
                tableNameExp,
                tableExp));
        // root.getRootSchema().removeTable(tableName);
        cleanUpFunctionExp =
            Expressions.lambda(Function0.class,
                Expressions.call(
                    Expressions.call(implementor.getRootExpression(),
                        BuiltInMethod.DATA_CONTEXT_GET_ROOT_SCHEMA.method),
                    BuiltInMethod.SCHEMA_PLUS_REMOVE_TABLE.method, tableNameExp));
      }
  
      Result seedResult = implementor.visitChild(this, 0, (EnumerableRel) seed, pref);
      Result iterationResult = implementor.visitChild(this, 1, (EnumerableRel) iteration, pref);
  
      Expression seedExp = builder.append("seed", seedResult.block);
      Expression iterativeExp = builder.append("iteration", iterationResult.block);
  
      PhysType physType =
          PhysTypeImpl.of(implementor.getTypeFactory(), getRowType(),
              pref.prefer(seedResult.format));
  
      Expression unionExp =
          Expressions.call(BuiltInMethod.REPEAT_UNION.method,
              seedExp,
              iterativeExp,
              Expressions.constant(iterationLimit, int.class),
              Expressions.constant(all, boolean.class),
              Util.first(physType.comparer(),
                  Expressions.call(BuiltInMethod.IDENTITY_COMPARER.method)),
              cleanUpFunctionExp);
      builder.add(unionExp);
  
      return implementor.result(physType, builder.toBlock());
    }
  
  }
  