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+/*
+ * 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.commons.math3.random;
+
+import org.apache.commons.math3.exception.NotStrictlyPositiveException;
+
+import java.util.Random;
+
+/**
+ * Utilities for creating {@link RandomGenerator} instances.
+ *
+ * @since 3.3
+ */
+public class RandomGeneratorFactory {
+ /** Class contains only static methods. */
+ private RandomGeneratorFactory() {}
+
+ /**
+ * Creates a {@link RandomDataGenerator} instance that wraps a {@link Random} instance.
+ *
+ * @param rng JDK {@link Random} instance that will generate the the random data.
+ * @return the given RNG, wrapped in a {@link RandomGenerator}.
+ */
+ public static RandomGenerator createRandomGenerator(final Random rng) {
+ return new RandomGenerator() {
+ /** {@inheritDoc} */
+ public void setSeed(int seed) {
+ rng.setSeed((long) seed);
+ }
+
+ /** {@inheritDoc} */
+ public void setSeed(int[] seed) {
+ rng.setSeed(convertToLong(seed));
+ }
+
+ /** {@inheritDoc} */
+ public void setSeed(long seed) {
+ rng.setSeed(seed);
+ }
+
+ /** {@inheritDoc} */
+ public void nextBytes(byte[] bytes) {
+ rng.nextBytes(bytes);
+ }
+
+ /** {@inheritDoc} */
+ public int nextInt() {
+ return rng.nextInt();
+ }
+
+ /** {@inheritDoc} */
+ public int nextInt(int n) {
+ if (n <= 0) {
+ throw new NotStrictlyPositiveException(n);
+ }
+ return rng.nextInt(n);
+ }
+
+ /** {@inheritDoc} */
+ public long nextLong() {
+ return rng.nextLong();
+ }
+
+ /** {@inheritDoc} */
+ public boolean nextBoolean() {
+ return rng.nextBoolean();
+ }
+
+ /** {@inheritDoc} */
+ public float nextFloat() {
+ return rng.nextFloat();
+ }
+
+ /** {@inheritDoc} */
+ public double nextDouble() {
+ return rng.nextDouble();
+ }
+
+ /** {@inheritDoc} */
+ public double nextGaussian() {
+ return rng.nextGaussian();
+ }
+ };
+ }
+
+ /**
+ * Converts seed from one representation to another.
+ *
+ * @param seed Original seed.
+ * @return the converted seed.
+ */
+ public static long convertToLong(int[] seed) {
+ // The following number is the largest prime that fits
+ // in 32 bits (i.e. 2^32 - 5).
+ final long prime = 4294967291l;
+
+ long combined = 0l;
+ for (int s : seed) {
+ combined = combined * prime + s;
+ }
+
+ return combined;
+ }
+}