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.beam.sdk.extensions.sql.impl.rule;
  
  import static org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions.checkArgument;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import org.apache.beam.sdk.extensions.sql.impl.rel.BeamLogicalConvention;
  import org.apache.beam.sdk.extensions.sql.impl.rel.BeamTableFunctionScanRel;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.plan.Convention;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.RelNode;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.convert.ConverterRule;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.core.TableFunctionScan;
  import org.apache.beam.vendor.calcite.v1_40_0.org.apache.calcite.rel.logical.LogicalTableFunctionScan;
  
  /**
   * This is the conveter rule that converts a Calcite {@code TableFunctionScan} to Beam {@code
   * TableFunctionScanRel}.
   */
  @SuppressWarnings({
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  public class BeamTableFunctionScanRule extends ConverterRule {
    public static final BeamTableFunctionScanRule INSTANCE = new BeamTableFunctionScanRule();
  
    private BeamTableFunctionScanRule() {
      super(
          LogicalTableFunctionScan.class,
          Convention.NONE,
          BeamLogicalConvention.INSTANCE,
          "BeamTableFunctionScanRule");
    }
  
    @Override
    public RelNode convert(RelNode relNode) {
      TableFunctionScan tableFunctionScan = (TableFunctionScan) relNode;
      // only support one input for table function scan.
      List<RelNode> inputs = new ArrayList<>();
      checkArgument(
          relNode.getInputs().size() == 1,
          "Wrong number of inputs for %s, expected 1 input but received: %s",
          BeamTableFunctionScanRel.class.getSimpleName(),
          relNode.getInputs().size());
      inputs.add(
          convert(
              relNode.getInput(0),
              relNode.getInput(0).getTraitSet().replace(BeamLogicalConvention.INSTANCE)));
      return new BeamTableFunctionScanRel(
          tableFunctionScan.getCluster(),
          tableFunctionScan.getTraitSet().replace(BeamLogicalConvention.INSTANCE),
          inputs,
          tableFunctionScan.getCall(),
          null,
          tableFunctionScan.getCall().getType(),
          Collections.EMPTY_SET);
    }
  }
  