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.spark;
  
  import org.apache.calcite.DataContext;
  import org.apache.calcite.linq4j.Enumerable;
  import org.apache.calcite.linq4j.Linq4j;
  
  import org.apache.spark.api.java.JavaRDD;
  import org.apache.spark.api.java.JavaSparkContext;
  import org.apache.spark.api.java.function.FlatMapFunction;
  
  import java.util.Arrays;
  import java.util.List;
  
  /**
   * Runtime utilities for Calcite's Spark adapter. Generated code calls these
   * methods.
   */
  public abstract class SparkRuntime {
    private SparkRuntime() {}
  
    /** Converts an array into an RDD. */
    public static <T> JavaRDD<T> createRdd(JavaSparkContext sc, T[] ts) {
      final List<T> list = Arrays.asList(ts);
      return sc.parallelize(list);
    }
  
    /** Converts an enumerable into an RDD. */
    public static <T> JavaRDD<T> createRdd(JavaSparkContext sc,
        Enumerable<T> enumerable) {
      final List<T> list = enumerable.toList();
      return sc.parallelize(list);
    }
  
    /** Converts an RDD into an enumerable. */
    public static <T> Enumerable<T> asEnumerable(JavaRDD<T> rdd) {
      return Linq4j.asEnumerable(rdd.collect());
    }
  
    /** Returns the Spark context for the current execution.
     *
     * <p>Currently a global variable; maybe later held within {@code root}.
     */
    public static JavaSparkContext getSparkContext(DataContext root) {
      return (JavaSparkContext) SparkHandlerImpl.instance().sparkContext();
    }
  
    /** Combines linq4j {@link org.apache.calcite.linq4j.function.Function}
     * and Spark {@link org.apache.spark.api.java.function.FlatMapFunction}.
     *
     * @param <T> argument type
     * @param <R> result type */
    public abstract static class CalciteFlatMapFunction<T, R>
        implements FlatMapFunction<T, R>,
        org.apache.calcite.linq4j.function.Function {
    }
  }
  