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.runtime;
  
  import org.apache.calcite.linq4j.function.Deterministic;
  import org.apache.calcite.linq4j.function.Parameter;
  
  import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
  
  import java.util.Random;
  
  /**
   * Function object for {@code RAND} and {@code RAND_INTEGER}, with and without
   * seed.
   */
  @SuppressWarnings("unused")
  public class RandomFunction {
    private @MonotonicNonNull Random random;
  
    /** Creates a RandomFunction.
     *
     * <p>Marked deterministic so that the code generator instantiates one once
     * per query, not once per row. */
    @Deterministic public RandomFunction() {
    }
  
    /** Implements the {@code RAND()} SQL function. */
    public double rand() {
      if (random == null) {
        random = new Random();
      }
      return random.nextDouble();
    }
  
    /** Implements the {@code RAND(seed)} SQL function. */
    public double randSeed(@Parameter(name = "seed") int seed) {
      if (random == null) {
        random = new Random(seed ^ (seed << 16));
      }
      return random.nextDouble();
    }
  
    /** Implements the {@code RAND_INTEGER(bound)} SQL function. */
    public int randInteger(@Parameter(name = "bound") int bound) {
      if (random == null) {
        random = new Random();
      }
      return random.nextInt(bound);
    }
  
    /** Implements the {@code RAND_INTEGER(seed, bound)} SQL function. */
    public int randIntegerSeed(@Parameter(name = "seed") int seed,
        @Parameter(name = "bound") int bound) {
      if (random == null) {
        random = new Random(seed);
      }
      return random.nextInt(bound);
    }
  
  }
  