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.tools;
  
  import org.apache.calcite.interpreter.Bindables;
  import org.apache.calcite.plan.RelOptTable;
  import org.apache.calcite.rel.RelHomogeneousShuttle;
  import org.apache.calcite.rel.RelNode;
  import org.apache.calcite.rel.RelShuttle;
  import org.apache.calcite.rel.core.TableScan;
  import org.apache.calcite.rel.logical.LogicalTableScan;
  import org.apache.calcite.util.Util;
  
  import java.sql.Connection;
  import java.sql.DriverManager;
  import java.sql.PreparedStatement;
  import java.sql.SQLException;
  
  /** Implementations of {@link RelRunner}. */
  public class RelRunners {
    private RelRunners() {}
  
    /** Runs a relational expression by creating a JDBC connection. */
    public static PreparedStatement run(RelNode rel) {
      final RelShuttle shuttle = new RelHomogeneousShuttle() {
        @Override public RelNode visit(TableScan scan) {
          final RelOptTable table = scan.getTable();
          if (scan instanceof LogicalTableScan
              && Bindables.BindableTableScan.canHandle(table)) {
            // Always replace the LogicalTableScan with BindableTableScan
            // because it's implementation does not require a "schema" as context.
            return Bindables.BindableTableScan.create(scan.getCluster(), table);
          }
          return super.visit(scan);
        }
      };
      rel = rel.accept(shuttle);
      try (Connection connection = DriverManager.getConnection("jdbc:calcite:")) {
        final RelRunner runner = connection.unwrap(RelRunner.class);
        return runner.prepareStatement(rel);
      } catch (SQLException e) {
        throw Util.throwAsRuntime(e);
      }
    }
  }
  