com.hazelcast.org.apache.calcite.runtime.RandomFunction Maven / Gradle / Ivy
/*
* 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 com.hazelcast.com.liance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.com.hazelcast.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 com.hazelcast.org.apache.calcite.runtime;
import com.hazelcast.org.apache.calcite.linq4j.function.Deterministic;
import com.hazelcast.org.apache.calcite.linq4j.function.Parameter;
import java.util.Random;
/**
* Function object for {@code RAND} and {@code RAND_INTEGER}, with and without
* seed.
*/
@SuppressWarnings("unused")
public class RandomFunction {
private Random random;
/** Creates a RandomFunction.
*
* 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);
}
}