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/*
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* Copyright (c) 2013, 2019, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.util.random;
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import java.util.function.Consumer;
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import java.util.function.DoubleConsumer;
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import java.util.function.IntConsumer;
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import java.util.function.LongConsumer;
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import java.util.random.RandomGenerator.SplittableGenerator;
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import java.util.Spliterator;
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import java.util.stream.DoubleStream;
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import java.util.stream.IntStream;
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import java.util.stream.LongStream;
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import java.util.stream.Stream;
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import java.util.stream.StreamSupport;
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/**
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* Low-level utility methods helpful for implementing pseudorandom number generators.
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*
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* This class is mostly for library writers creating specific implementations of the
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* interface {@link RandomGenerator}.
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*
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* @since 14
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*/
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public class RandomSupport {
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/*
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* Implementation Overview.
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*
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* This class provides utility methods and constants frequently
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* useful in the implementation of pseudorandom number generators
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* that satisfy the interface {@link RandomGenerator}.
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*
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* File organization: First some message strings, then the main
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* public methods, followed by a non-public base spliterator class.
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*/
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// IllegalArgumentException messages
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static final String BAD_SIZE = "size must be non-negative";
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static final String BAD_DISTANCE = "jump distance must be finite, positive, and an exact integer";
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static final String BAD_BOUND = "bound must be positive";
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static final String BAD_FLOATING_BOUND = "bound must be finite and positive";
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static final String BAD_RANGE = "bound must be greater than origin";
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/* ---------------- public methods ---------------- */
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/**
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* Check a {@code long} proposed stream size for validity.
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*
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* @param streamSize the proposed stream size
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*
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* @throws IllegalArgumentException if {@code streamSize} is negative
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*/
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public static void checkStreamSize(long streamSize) {
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if (streamSize < 0L)
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throw new IllegalArgumentException(BAD_SIZE);
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}
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/**
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* Check a {@code double} proposed jump distance for validity.
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*
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* @param distance the proposed jump distance
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*
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* @throws IllegalArgumentException if {@code size} fails to be positive, finite, and an exact integer
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*/
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public static void checkJumpDistance(double distance) {
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if (!(distance > 0.0 && distance < Float.POSITIVE_INFINITY
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&& distance == Math.floor(distance))) {
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throw new IllegalArgumentException(BAD_DISTANCE);
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}
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}
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/**
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* Checks a {@code float} upper bound value for validity.
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*
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* @param bound the upper bound (exclusive)
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*
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* @throws IllegalArgumentException if {@code bound} fails to be positive and finite
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*/
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public static void checkBound(float bound) {
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if (!(bound > 0.0 && bound < Float.POSITIVE_INFINITY)) {
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throw new IllegalArgumentException(BAD_FLOATING_BOUND);
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}
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}
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/**
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* Checks a {@code double} upper bound value for validity.
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*
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* @param bound the upper bound (exclusive)
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*
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* @throws IllegalArgumentException if {@code bound} fails to be positive and finite
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*/
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public static void checkBound(double bound) {
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if (!(bound > 0.0 && bound < Double.POSITIVE_INFINITY)) {
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throw new IllegalArgumentException(BAD_FLOATING_BOUND);
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}
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}
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/**
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* Checks an {@code int} upper bound value for validity.
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*
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* @param bound the upper bound (exclusive)
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*
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* @throws IllegalArgumentException if {@code bound} is not positive
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*/
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public static void checkBound(int bound) {
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if (bound <= 0) {
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throw new IllegalArgumentException(BAD_BOUND);
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}
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}
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/**
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* Checks a {@code long} upper bound value for validity.
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*
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* @param bound the upper bound (exclusive)
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*
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* @throws IllegalArgumentException if {@code bound} is not positive
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*/
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public static void checkBound(long bound) {
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if (bound <= 0) {
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throw new IllegalArgumentException(BAD_BOUND);
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}
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}
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/**
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* Checks a {@code float} range for validity.
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*
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* @param origin the least value (inclusive) in the range
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* @param bound the upper bound (exclusive) of the range
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*
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* @throws IllegalArgumentException if {@code origin} is not finite, {@code bound} is not finite,
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* or {@code bound - origin} is not finite
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*/
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public static void checkRange(float origin, float bound) {
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if (!(origin < bound && (bound - origin) < Float.POSITIVE_INFINITY)) {
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throw new IllegalArgumentException(BAD_RANGE);
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}
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}
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/**
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* Checks a {@code double} range for validity.
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*
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* @param origin the least value (inclusive) in the range
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* @param bound the upper bound (exclusive) of the range
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*
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* @throws IllegalArgumentException if {@code origin} is not finite, {@code bound} is not finite,
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* or {@code bound - origin} is not finite
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*/
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public static void checkRange(double origin, double bound) {
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if (!(origin < bound && (bound - origin) < Double.POSITIVE_INFINITY)) {
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throw new IllegalArgumentException(BAD_RANGE);
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}
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}
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/**
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* Checks an {@code int} range for validity.
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*
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* @param origin the least value that can be returned
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* @param bound the upper bound (exclusive) for the returned value
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*
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* @throws IllegalArgumentException if {@code origin} is greater than or equal to {@code bound}
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*/
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public static void checkRange(int origin, int bound) {
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if (origin >= bound) {
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throw new IllegalArgumentException(BAD_RANGE);
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}
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}
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/**
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* Checks a {@code long} range for validity.
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*
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* @param origin the least value that can be returned
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* @param bound the upper bound (exclusive) for the returned value
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*
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* @throws IllegalArgumentException if {@code origin} is greater than or equal to {@code bound}
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*/
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public static void checkRange(long origin, long bound) {
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if (origin >= bound) {
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throw new IllegalArgumentException(BAD_RANGE);
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}
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}
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/**
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* Given an array of seed bytes of any length, construct an array
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* of {@code long} seed values of length {@code n}, such that the
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* last {@code z} values are not all zero.
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*
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* @param seed an array of {@code byte} values
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* @param n the length of the result array (should be nonnegative)
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* @param z the number of trailing result elements that are required
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* to be not all zero (should be nonnegative but not larger
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* than {@code n})
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*
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* @return an array of length {@code n} containing {@code long} seed values
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*/
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public static long[] convertSeedBytesToLongs(byte[] seed, int n, int z) {
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final long[] result = new long[n];
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final int m = Math.min(seed.length, n << 3);
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// Distribute seed bytes into the words to be formed.
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for (int j = 0; j < m; j++) {
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result[j>>3] = (result[j>>3] << 8) | seed[j];
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}
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// If there aren't enough seed bytes for all the words we need,
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// use a SplitMix-style PRNG to fill in the rest.
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long v = result[0];
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for (int j = (m + 7) >> 3; j < n; j++) {
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result[j] = mixMurmur64(v += SILVER_RATIO_64);
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}
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// Finally, we need to make sure the last z words are not all zero.
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search: {
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for (int j = n - z; j < n; j++) {
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if (result[j] != 0) break search;
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}
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// If they are, fill in using a SplitMix-style PRNG.
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// Using "& ~1L" in the next line defends against the case z==1
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// by guaranteeing that the first generated value will be nonzero.
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long w = result[0] & ~1L;
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for (int j = n - z; j < n; j++) {
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result[j] = mixMurmur64(w += SILVER_RATIO_64);
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}
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}
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return result;
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}
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/**
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* Given an array of seed bytes of any length, construct an array
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* of {@code int} seed values of length {@code n}, such that the
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* last {@code z} values are not all zero.
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*
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* @param seed an array of {@code byte} values
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* @param n the length of the result array (should be nonnegative)
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* @param z the number of trailing result elements that are required
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* to be not all zero (should be nonnegative but not larger
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* than {@code n})
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*
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* @return an array of length {@code n} containing {@code int} seed values
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*/
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public static int[] convertSeedBytesToInts(byte[] seed, int n, int z) {
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final int[] result = new int[n];
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final int m = Math.min(seed.length, n << 2);
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// Distribute seed bytes into the words to be formed.
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for (int j = 0; j < m; j++) {
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result[j>>2] = (result[j>>2] << 8) | seed[j];
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}
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// If there aren't enough seed bytes for all the words we need,
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// use a SplitMix-style PRNG to fill in the rest.
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int v = result[0];
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for (int j = (m + 3) >> 2; j < n; j++) {
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result[j] = mixMurmur32(v += SILVER_RATIO_32);
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}
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// Finally, we need to make sure the last z words are not all zero.
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search: {
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for (int j = n - z; j < n; j++) {
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if (result[j] != 0) break search;
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}
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// If they are, fill in using a SplitMix-style PRNG.
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// Using "& ~1" in the next line defends against the case z==1
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// by guaranteeing that the first generated value will be nonzero.
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int w = result[0] & ~1;
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for (int j = n - z; j < n; j++) {
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result[j] = mixMurmur32(w += SILVER_RATIO_32);
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}
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}
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return result;
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}
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/*
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* Bounded versions of nextX methods used by streams, as well as
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* the public nextX(origin, bound) methods. These exist mainly to
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* avoid the need for multiple versions of stream spliterators
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* across the different exported forms of streams.
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*/
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/**
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* This is the form of {@code nextLong} used by a {@link LongStream}
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* {@link Spliterator} and by the public method
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* {@code nextLong(origin, bound)}. If {@code origin} is greater
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* than {@code bound}, then this method simply calls the unbounded
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* version of {@code nextLong()}, choosing pseudorandomly from
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* among all 2<sup>64</sup> possible {@code long} values}, and
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* otherwise uses one or more calls to {@code nextLong()} to
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* choose a value pseudorandomly from the possible values
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* between {@code origin} (inclusive) and {@code bound} (exclusive).
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*
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* @implNote This method first calls {@code nextLong()} to obtain
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* a {@code long} value that is assumed to be pseudorandomly
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* chosen uniformly and independently from the 2<sup>64</sup>
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* possible {@code long} values (that is, each of the 2<sup>64</sup>
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* possible long values is equally likely to be chosen).
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* Under some circumstances (when the specified range is not
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* a power of 2), {@code nextLong()} may be called additional times
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* to ensure that that the values in the specified range are
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* equally likely to be chosen (provided the assumption holds).
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* <p>
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* The implementation considers four cases:
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* <ol>
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*
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* <li> If the {@code} bound} is less than or equal to the {@code origin}
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* (indicated an unbounded form), the 64-bit {@code long} value
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* obtained from {@code nextLong()} is returned directly.
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*
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* <li> Otherwise, if the length <i>n</i> of the specified range is an
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* exact power of two 2<sup><i>m</i></sup> for some integer
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* <i>m</i>, then return the sum of {@code origin} and the
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* <i>m</i> lowest-order bits of the value from {@code nextLong()}.
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*
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* <li> Otherwise, if the length <i>n</i> of the specified range
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* is less than 2<sup>63</sup>, then the basic idea is to use the
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* remainder modulo <i>n</i> of the value from {@code nextLong()},
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* but with this approach some values will be over-represented.
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* Therefore a loop is used to avoid potential bias by rejecting
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* candidates that are too large. Assuming that the results from
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* {@code nextLong()} are truly chosen uniformly and independently,
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* the expected number of iterations will be somewhere between
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* 1 and 2, depending on the precise value of <i>n</i>.
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*
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* <li> Otherwise, the length <i>n</i> of the specified range
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* cannot be represented as a positive {@code long} value.
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|
342 |
* A loop repeatedly calls {@code nextlong()} until obtaining
|
|
|
343 |
* a suitable candidate, Again, the expected number of iterations
|
|
|
344 |
* is less than 2.
|
|
|
345 |
*
|
|
|
346 |
* </ol>
|
|
|
347 |
*
|
|
|
348 |
* @param rng a random number generator to be used as a
|
|
|
349 |
* source of pseudorandom {@code long} values
|
|
|
350 |
* @param origin the least value that can be produced,
|
|
|
351 |
* unless greater than or equal to {@code bound}
|
|
|
352 |
* @param bound the upper bound (exclusive), unless {@code origin}
|
|
|
353 |
* is greater than or equal to {@code bound}
|
|
|
354 |
*
|
|
|
355 |
* @return a pseudorandomly chosen {@code long} value,
|
|
|
356 |
* which will be between {@code origin} (inclusive) and
|
|
|
357 |
* {@code bound} exclusive unless {@code origin}
|
|
|
358 |
* is greater than or equal to {@code bound}
|
|
|
359 |
*/
|
|
|
360 |
public static long boundedNextLong(RandomGenerator rng, long origin, long bound) {
|
|
|
361 |
long r = rng.nextLong();
|
|
|
362 |
if (origin < bound) {
|
|
|
363 |
// It's not case (1).
|
|
|
364 |
final long n = bound - origin;
|
|
|
365 |
final long m = n - 1;
|
|
|
366 |
if ((n & m) == 0L) {
|
|
|
367 |
// It is case (2): length of range is a power of 2.
|
|
|
368 |
r = (r & m) + origin;
|
|
|
369 |
} else if (n > 0L) {
|
|
|
370 |
// It is case (3): need to reject over-represented candidates.
|
|
|
371 |
/* This loop takes an unlovable form (but it works):
|
|
|
372 |
because the first candidate is already available,
|
|
|
373 |
we need a break-in-the-middle construction,
|
|
|
374 |
which is concisely but cryptically performed
|
|
|
375 |
within the while-condition of a body-less for loop. */
|
|
|
376 |
for (long u = r >>> 1; // ensure nonnegative
|
|
|
377 |
u + m - (r = u % n) < 0L; // rejection check
|
|
|
378 |
u = rng.nextLong() >>> 1) // retry
|
|
|
379 |
;
|
|
|
380 |
r += origin;
|
|
|
381 |
}
|
|
|
382 |
else {
|
|
|
383 |
// It is case (4): length of range not representable as long.
|
|
|
384 |
while (r < origin || r >= bound)
|
|
|
385 |
r = rng.nextLong();
|
|
|
386 |
}
|
|
|
387 |
}
|
|
|
388 |
return r;
|
|
|
389 |
}
|
|
|
390 |
|
|
|
391 |
/**
|
|
|
392 |
* This is the form of {@code nextLong} used by the public method
|
|
|
393 |
* {@code nextLong(bound)}. This is essentially a version of
|
|
|
394 |
* {@code boundedNextLong(origin, bound)} that has been
|
|
|
395 |
* specialized for the case where the {@code origin} is zero
|
|
|
396 |
* and the {@code bound} is greater than zero. The value
|
|
|
397 |
* returned is chosen pseudorandomly from nonnegative integer
|
|
|
398 |
* values less than {@code bound}.
|
|
|
399 |
*
|
|
|
400 |
* @implNote This method first calls {@code nextLong()} to obtain
|
|
|
401 |
* a {@code long} value that is assumed to be pseudorandomly
|
|
|
402 |
* chosen uniformly and independently from the 2<sup>64</sup>
|
|
|
403 |
* possible {@code long} values (that is, each of the 2<sup>64</sup>
|
|
|
404 |
* possible long values is equally likely to be chosen).
|
|
|
405 |
* Under some circumstances (when the specified range is not
|
|
|
406 |
* a power of 2), {@code nextLong()} may be called additional times
|
|
|
407 |
* to ensure that that the values in the specified range are
|
|
|
408 |
* equally likely to be chosen (provided the assumption holds).
|
|
|
409 |
* <p>
|
|
|
410 |
* The implementation considers two cases:
|
|
|
411 |
* <ol>
|
|
|
412 |
*
|
|
|
413 |
* <li> If {@code bound} is an exact power of two 2<sup><i>m</i></sup>
|
|
|
414 |
* for some integer <i>m</i>, then return the sum of {@code origin}
|
|
|
415 |
* and the <i>m</i> lowest-order bits of the value from
|
|
|
416 |
* {@code nextLong()}.
|
|
|
417 |
*
|
|
|
418 |
* <li> Otherwise, the basic idea is to use the remainder modulo
|
|
|
419 |
* <i>bound</i> of the value from {@code nextLong()},
|
|
|
420 |
* but with this approach some values will be over-represented.
|
|
|
421 |
* Therefore a loop is used to avoid potential bias by rejecting
|
|
|
422 |
* candidates that vare too large. Assuming that the results from
|
|
|
423 |
* {@code nextLong()} are truly chosen uniformly and independently,
|
|
|
424 |
* the expected number of iterations will be somewhere between
|
|
|
425 |
* 1 and 2, depending on the precise value of <i>bound</i>.
|
|
|
426 |
*
|
|
|
427 |
* </ol>
|
|
|
428 |
*
|
|
|
429 |
* @param rng a random number generator to be used as a
|
|
|
430 |
* source of pseudorandom {@code long} values
|
|
|
431 |
* @param bound the upper bound (exclusive); must be greater than zero
|
|
|
432 |
*
|
|
|
433 |
* @return a pseudorandomly chosen {@code long} value
|
|
|
434 |
*/
|
|
|
435 |
public static long boundedNextLong(RandomGenerator rng, long bound) {
|
|
|
436 |
// Specialize boundedNextLong for origin == 0, bound > 0
|
|
|
437 |
final long m = bound - 1;
|
|
|
438 |
long r = rng.nextLong();
|
|
|
439 |
if ((bound & m) == 0L) {
|
|
|
440 |
// The bound is a power of 2.
|
|
|
441 |
r &= m;
|
|
|
442 |
} else {
|
|
|
443 |
// Must reject over-represented candidates
|
|
|
444 |
/* This loop takes an unlovable form (but it works):
|
|
|
445 |
because the first candidate is already available,
|
|
|
446 |
we need a break-in-the-middle construction,
|
|
|
447 |
which is concisely but cryptically performed
|
|
|
448 |
within the while-condition of a body-less for loop. */
|
|
|
449 |
for (long u = r >>> 1;
|
|
|
450 |
u + m - (r = u % bound) < 0L;
|
|
|
451 |
u = rng.nextLong() >>> 1)
|
|
|
452 |
;
|
|
|
453 |
}
|
|
|
454 |
return r;
|
|
|
455 |
}
|
|
|
456 |
|
|
|
457 |
/**
|
|
|
458 |
* This is the form of {@code nextInt} used by an {@link IntStream}
|
|
|
459 |
* {@link Spliterator} and by the public method
|
|
|
460 |
* {@code nextInt(origin, bound)}. If {@code origin} is greater
|
|
|
461 |
* than {@code bound}, then this method simply calls the unbounded
|
|
|
462 |
* version of {@code nextInt()}, choosing pseudorandomly from
|
|
|
463 |
* among all 2<sup>64</sup> possible {@code int} values}, and
|
|
|
464 |
* otherwise uses one or more calls to {@code nextInt()} to
|
|
|
465 |
* choose a value pseudorandomly from the possible values
|
|
|
466 |
* between {@code origin} (inclusive) and {@code bound} (exclusive).
|
|
|
467 |
*
|
|
|
468 |
* @param rng a random number generator to be used as a
|
|
|
469 |
* source of pseudorandom {@code int} values
|
|
|
470 |
* @param origin the least value that can be produced,
|
|
|
471 |
* unless greater than or equal to {@code bound}
|
|
|
472 |
* @param bound the upper bound (exclusive), unless {@code origin}
|
|
|
473 |
* is greater than or equal to {@code bound}
|
|
|
474 |
*
|
|
|
475 |
* @return a pseudorandomly chosen {@code int} value,
|
|
|
476 |
* which will be between {@code origin} (inclusive) and
|
|
|
477 |
* {@code bound} exclusive unless {@code origin}
|
|
|
478 |
* is greater than or equal to {@code bound}
|
|
|
479 |
*
|
|
|
480 |
* @implNote The implementation of this method is identical to
|
|
|
481 |
* the implementation of {@code nextLong(origin, bound)}
|
|
|
482 |
* except that {@code int} values and the {@code nextInt()}
|
|
|
483 |
* method are used rather than {@code long} values and the
|
|
|
484 |
* {@code nextLong()} method.
|
|
|
485 |
*/
|
|
|
486 |
public static int boundedNextInt(RandomGenerator rng, int origin, int bound) {
|
|
|
487 |
int r = rng.nextInt();
|
|
|
488 |
if (origin < bound) {
|
|
|
489 |
// It's not case (1).
|
|
|
490 |
final int n = bound - origin;
|
|
|
491 |
final int m = n - 1;
|
|
|
492 |
if ((n & m) == 0) {
|
|
|
493 |
// It is case (2): length of range is a power of 2.
|
|
|
494 |
r = (r & m) + origin;
|
|
|
495 |
} else if (n > 0) {
|
|
|
496 |
// It is case (3): need to reject over-represented candidates.
|
|
|
497 |
for (int u = r >>> 1;
|
|
|
498 |
u + m - (r = u % n) < 0;
|
|
|
499 |
u = rng.nextInt() >>> 1)
|
|
|
500 |
;
|
|
|
501 |
r += origin;
|
|
|
502 |
}
|
|
|
503 |
else {
|
|
|
504 |
// It is case (4): length of range not representable as long.
|
|
|
505 |
while (r < origin || r >= bound) {
|
|
|
506 |
r = rng.nextInt();
|
|
|
507 |
}
|
|
|
508 |
}
|
|
|
509 |
}
|
|
|
510 |
return r;
|
|
|
511 |
}
|
|
|
512 |
|
|
|
513 |
/**
|
|
|
514 |
* This is the form of {@code nextInt} used by the public method
|
|
|
515 |
* {@code nextInt(bound)}. This is essentially a version of
|
|
|
516 |
* {@code boundedNextInt(origin, bound)} that has been
|
|
|
517 |
* specialized for the case where the {@code origin} is zero
|
|
|
518 |
* and the {@code bound} is greater than zero. The value
|
|
|
519 |
* returned is chosen pseudorandomly from nonnegative integer
|
|
|
520 |
* values less than {@code bound}.
|
|
|
521 |
*
|
|
|
522 |
* @param rng a random number generator to be used as a
|
|
|
523 |
* source of pseudorandom {@code long} values
|
|
|
524 |
* @param bound the upper bound (exclusive); must be greater than zero
|
|
|
525 |
*
|
|
|
526 |
* @return a pseudorandomly chosen {@code long} value
|
|
|
527 |
*
|
|
|
528 |
* @implNote The implementation of this method is identical to
|
|
|
529 |
* the implementation of {@code nextLong(bound)}
|
|
|
530 |
* except that {@code int} values and the {@code nextInt()}
|
|
|
531 |
* method are used rather than {@code long} values and the
|
|
|
532 |
* {@code nextLong()} method.
|
|
|
533 |
*/
|
|
|
534 |
public static int boundedNextInt(RandomGenerator rng, int bound) {
|
|
|
535 |
// Specialize boundedNextInt for origin == 0, bound > 0
|
|
|
536 |
final int m = bound - 1;
|
|
|
537 |
int r = rng.nextInt();
|
|
|
538 |
if ((bound & m) == 0) {
|
|
|
539 |
// The bound is a power of 2.
|
|
|
540 |
r &= m;
|
|
|
541 |
} else {
|
|
|
542 |
// Must reject over-represented candidates
|
|
|
543 |
for (int u = r >>> 1;
|
|
|
544 |
u + m - (r = u % bound) < 0;
|
|
|
545 |
u = rng.nextInt() >>> 1)
|
|
|
546 |
;
|
|
|
547 |
}
|
|
|
548 |
return r;
|
|
|
549 |
}
|
|
|
550 |
|
|
|
551 |
/**
|
|
|
552 |
* This is the form of {@code nextDouble} used by a {@link DoubleStream}
|
|
|
553 |
* {@link Spliterator} and by the public method
|
|
|
554 |
* {@code nextDouble(origin, bound)}. If {@code origin} is greater
|
|
|
555 |
* than {@code bound}, then this method simply calls the unbounded
|
|
|
556 |
* version of {@code nextDouble()}, and otherwise scales and translates
|
|
|
557 |
* the result of a call to {@code nextDouble()} so that it lies
|
|
|
558 |
* between {@code origin} (inclusive) and {@code bound} (exclusive).
|
|
|
559 |
*
|
|
|
560 |
* @implNote The implementation considers two cases:
|
|
|
561 |
* <ol>
|
|
|
562 |
*
|
|
|
563 |
* <li> If the {@code bound} is less than or equal to the {@code origin}
|
|
|
564 |
* (indicated an unbounded form), the 64-bit {@code double} value
|
|
|
565 |
* obtained from {@code nextDouble()} is returned directly.
|
|
|
566 |
*
|
|
|
567 |
* <li> Otherwise, the result of a call to {@code nextDouble} is
|
|
|
568 |
* multiplied by {@code (bound - origin)}, then {@code origin}
|
|
|
569 |
* is added, and then if this this result is not less than
|
|
|
570 |
* {@code bound} (which can sometimes occur because of rounding),
|
|
|
571 |
* it is replaced with the largest {@code double} value that
|
|
|
572 |
* is less than {@code bound}.
|
|
|
573 |
*
|
|
|
574 |
* </ol>
|
|
|
575 |
*
|
|
|
576 |
* @param rng a random number generator to be used as a
|
|
|
577 |
* source of pseudorandom {@code double} values
|
|
|
578 |
* @param origin the least value that can be produced,
|
|
|
579 |
* unless greater than or equal to {@code bound}; must be finite
|
|
|
580 |
* @param bound the upper bound (exclusive), unless {@code origin}
|
|
|
581 |
* is greater than or equal to {@code bound}; must be finite
|
|
|
582 |
* @return a pseudorandomly chosen {@code double} value,
|
|
|
583 |
* which will be between {@code origin} (inclusive) and
|
|
|
584 |
* {@code bound} exclusive unless {@code origin}
|
|
|
585 |
* is greater than or equal to {@code bound},
|
|
|
586 |
* in which case it will be between 0.0 (inclusive)
|
|
|
587 |
* and 1.0 (exclusive)
|
|
|
588 |
*/
|
|
|
589 |
public static double boundedNextDouble(RandomGenerator rng, double origin, double bound) {
|
|
|
590 |
double r = rng.nextDouble();
|
|
|
591 |
if (origin < bound) {
|
|
|
592 |
r = r * (bound - origin) + origin;
|
|
|
593 |
if (r >= bound) // may need to correct a rounding problem
|
|
|
594 |
r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
|
|
|
595 |
}
|
|
|
596 |
return r;
|
|
|
597 |
}
|
|
|
598 |
|
|
|
599 |
/**
|
|
|
600 |
* This is the form of {@code nextDouble} used by the public method
|
|
|
601 |
* {@code nextDouble(bound)}. This is essentially a version of
|
|
|
602 |
* {@code boundedNextDouble(origin, bound)} that has been
|
|
|
603 |
* specialized for the case where the {@code origin} is zero
|
|
|
604 |
* and the {@code bound} is greater than zero.
|
|
|
605 |
*
|
|
|
606 |
* @implNote The result of a call to {@code nextDouble} is
|
|
|
607 |
* multiplied by {@code bound}, and then if this result is
|
|
|
608 |
* not less than {@code bound} (which can sometimes occur
|
|
|
609 |
* because of rounding), it is replaced with the largest
|
|
|
610 |
* {@code double} value that is less than {@code bound}.
|
|
|
611 |
*
|
|
|
612 |
* @param rng a random number generator to be used as a
|
|
|
613 |
* source of pseudorandom {@code double} values
|
|
|
614 |
* @param bound the upper bound (exclusive); must be finite and
|
|
|
615 |
* greater than zero
|
|
|
616 |
* @return a pseudorandomly chosen {@code double} value
|
|
|
617 |
* between zero (inclusive) and {@code bound} (exclusive)
|
|
|
618 |
*/
|
|
|
619 |
public static double boundedNextDouble(RandomGenerator rng, double bound) {
|
|
|
620 |
// Specialize boundedNextDouble for origin == 0, bound > 0
|
|
|
621 |
double r = rng.nextDouble();
|
|
|
622 |
r = r * bound;
|
|
|
623 |
if (r >= bound) // may need to correct a rounding problem
|
|
|
624 |
r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
|
|
|
625 |
return r;
|
|
|
626 |
}
|
|
|
627 |
|
|
|
628 |
/**
|
|
|
629 |
* This is the form of {@code nextFloat} used by a {@code Stream<Float>}
|
|
|
630 |
* {@link Spliterator} (if there were any) and by the public method
|
|
|
631 |
* {@code nextFloat(origin, bound)}. If {@code origin} is greater
|
|
|
632 |
* than {@code bound}, then this method simply calls the unbounded
|
|
|
633 |
* version of {@code nextFloat()}, and otherwise scales and translates
|
|
|
634 |
* the result of a call to {@code nextFloat()} so that it lies
|
|
|
635 |
* between {@code origin} (inclusive) and {@code bound} (exclusive).
|
|
|
636 |
*
|
|
|
637 |
* @implNote The implementation of this method is identical to
|
|
|
638 |
* the implementation of {@code nextDouble(origin, bound)}
|
|
|
639 |
* except that {@code float} values and the {@code nextFloat()}
|
|
|
640 |
* method are used rather than {@code double} values and the
|
|
|
641 |
* {@code nextDouble()} method.
|
|
|
642 |
*
|
|
|
643 |
* @param rng a random number generator to be used as a
|
|
|
644 |
* source of pseudorandom {@code float} values
|
|
|
645 |
* @param origin the least value that can be produced,
|
|
|
646 |
* unless greater than or equal to {@code bound}; must be finite
|
|
|
647 |
* @param bound the upper bound (exclusive), unless {@code origin}
|
|
|
648 |
* is greater than or equal to {@code bound}; must be finite
|
|
|
649 |
* @return a pseudorandomly chosen {@code float} value,
|
|
|
650 |
* which will be between {@code origin} (inclusive) and
|
|
|
651 |
* {@code bound} exclusive unless {@code origin}
|
|
|
652 |
* is greater than or equal to {@code bound},
|
|
|
653 |
* in which case it will be between 0.0 (inclusive)
|
|
|
654 |
* and 1.0 (exclusive)
|
|
|
655 |
*/
|
|
|
656 |
public static float boundedNextFloat(RandomGenerator rng, float origin, float bound) {
|
|
|
657 |
float r = rng.nextFloat();
|
|
|
658 |
if (origin < bound) {
|
|
|
659 |
r = r * (bound - origin) + origin;
|
|
|
660 |
if (r >= bound) // may need to correct a rounding problem
|
|
|
661 |
r = Float.intBitsToFloat(Float.floatToIntBits(bound) - 1);
|
|
|
662 |
}
|
|
|
663 |
return r;
|
|
|
664 |
}
|
|
|
665 |
|
|
|
666 |
/**
|
|
|
667 |
* This is the form of {@code nextFloat} used by the public method
|
|
|
668 |
* {@code nextFloat(bound)}. This is essentially a version of
|
|
|
669 |
* {@code boundedNextFloat(origin, bound)} that has been
|
|
|
670 |
* specialized for the case where the {@code origin} is zero
|
|
|
671 |
* and the {@code bound} is greater than zero.
|
|
|
672 |
*
|
|
|
673 |
* @implNote The implementation of this method is identical to
|
|
|
674 |
* the implementation of {@code nextDouble(bound)}
|
|
|
675 |
* except that {@code float} values and the {@code nextFloat()}
|
|
|
676 |
* method are used rather than {@code double} values and the
|
|
|
677 |
* {@code nextDouble()} method.
|
|
|
678 |
*
|
|
|
679 |
* @param rng a random number generator to be used as a
|
|
|
680 |
* source of pseudorandom {@code float} values
|
|
|
681 |
* @param bound the upper bound (exclusive); must be finite and
|
|
|
682 |
* greater than zero
|
|
|
683 |
* @return a pseudorandomly chosen {@code float} value
|
|
|
684 |
* between zero (inclusive) and {@code bound} (exclusive)
|
|
|
685 |
*/
|
|
|
686 |
public static float boundedNextFloat(RandomGenerator rng, float bound) {
|
|
|
687 |
// Specialize boundedNextFloat for origin == 0, bound > 0
|
|
|
688 |
float r = rng.nextFloat();
|
|
|
689 |
r = r * bound;
|
|
|
690 |
if (r >= bound) // may need to correct a rounding problem
|
|
|
691 |
r = Float.intBitsToFloat(Float.floatToIntBits(bound) - 1);
|
|
|
692 |
return r;
|
|
|
693 |
}
|
|
|
694 |
|
|
|
695 |
// The following decides which of two strategies initialSeed() will use.
|
|
|
696 |
private static boolean secureRandomSeedRequested() {
|
|
|
697 |
String pp = java.security.AccessController.doPrivileged(
|
|
|
698 |
new sun.security.action.GetPropertyAction(
|
|
|
699 |
"java.util.secureRandomSeed"));
|
|
|
700 |
return (pp != null && pp.equalsIgnoreCase("true"));
|
|
|
701 |
}
|
|
|
702 |
|
|
|
703 |
private static final boolean useSecureRandomSeed = secureRandomSeedRequested();
|
|
|
704 |
|
|
|
705 |
/**
|
|
|
706 |
* Returns a {@code long} value (chosen from some
|
|
|
707 |
* machine-dependent entropy source) that may be useful for
|
|
|
708 |
* initializing a source of seed values for instances of {@link RandomGenerator}
|
|
|
709 |
* created by zero-argument constructors. (This method should
|
|
|
710 |
* <i>not</i> be called repeatedly, once per constructed
|
|
|
711 |
* object; at most it should be called once per class.)
|
|
|
712 |
*
|
|
|
713 |
* @return a {@code long} value, randomly chosen using
|
|
|
714 |
* appropriate environmental entropy
|
|
|
715 |
*/
|
|
|
716 |
public static long initialSeed() {
|
|
|
717 |
if (useSecureRandomSeed) {
|
|
|
718 |
byte[] seedBytes = java.security.SecureRandom.getSeed(8);
|
|
|
719 |
long s = (long)(seedBytes[0]) & 0xffL;
|
|
|
720 |
for (int i = 1; i < 8; ++i)
|
|
|
721 |
s = (s << 8) | ((long)(seedBytes[i]) & 0xffL);
|
|
|
722 |
return s;
|
|
|
723 |
}
|
|
|
724 |
return (mixStafford13(System.currentTimeMillis()) ^
|
|
|
725 |
mixStafford13(System.nanoTime()));
|
|
|
726 |
}
|
|
|
727 |
|
|
|
728 |
/**
|
|
|
729 |
* The first 32 bits of the golden ratio (1+sqrt(5))/2, forced to be odd.
|
|
|
730 |
* Useful for producing good Weyl sequences or as an arbitrary nonzero odd value.
|
|
|
731 |
*/
|
|
|
732 |
public static final int GOLDEN_RATIO_32 = 0x9e3779b9;
|
|
|
733 |
|
|
|
734 |
/**
|
|
|
735 |
* The first 64 bits of the golden ratio (1+sqrt(5))/2, forced to be odd.
|
|
|
736 |
* Useful for producing good Weyl sequences or as an arbitrary nonzero odd value.
|
|
|
737 |
*/
|
|
|
738 |
public static final long GOLDEN_RATIO_64 = 0x9e3779b97f4a7c15L;
|
|
|
739 |
|
|
|
740 |
/**
|
|
|
741 |
* The first 32 bits of the silver ratio 1+sqrt(2), forced to be odd.
|
|
|
742 |
* Useful for producing good Weyl sequences or as an arbitrary nonzero odd value.
|
|
|
743 |
*/
|
|
|
744 |
public static final int SILVER_RATIO_32 = 0x6A09E667;
|
|
|
745 |
|
|
|
746 |
/**
|
|
|
747 |
* The first 64 bits of the silver ratio 1+sqrt(2), forced to be odd.
|
|
|
748 |
* Useful for producing good Weyl sequences or as an arbitrary nonzero odd value.
|
|
|
749 |
*/
|
|
|
750 |
public static final long SILVER_RATIO_64 = 0x6A09E667F3BCC909L;
|
|
|
751 |
|
|
|
752 |
/**
|
|
|
753 |
* Computes the 64-bit mixing function for MurmurHash3.
|
|
|
754 |
* This is a 64-bit hashing function with excellent avalanche statistics.
|
|
|
755 |
* https://github.com/aappleby/smhasher/wiki/MurmurHash3
|
|
|
756 |
*
|
|
|
757 |
* Note that if the argument {@code z} is 0, the result is 0.
|
|
|
758 |
*
|
|
|
759 |
* @param z any long value
|
|
|
760 |
*
|
|
|
761 |
* @return the result of hashing z
|
|
|
762 |
*/
|
|
|
763 |
public static long mixMurmur64(long z) {
|
|
|
764 |
z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
|
|
|
765 |
z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
|
|
|
766 |
return z ^ (z >>> 33);
|
|
|
767 |
}
|
|
|
768 |
|
|
|
769 |
/**
|
|
|
770 |
* Computes Stafford variant 13 of the 64-bit mixing function for MurmurHash3.
|
|
|
771 |
* This is a 64-bit hashing function with excellent avalanche statistics.
|
|
|
772 |
* http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html
|
|
|
773 |
*
|
|
|
774 |
* Note that if the argument {@code z} is 0, the result is 0.
|
|
|
775 |
*
|
|
|
776 |
* @param z any long value
|
|
|
777 |
*
|
|
|
778 |
* @return the result of hashing z
|
|
|
779 |
*/
|
|
|
780 |
public static long mixStafford13(long z) {
|
|
|
781 |
z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L;
|
|
|
782 |
z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL;
|
|
|
783 |
return z ^ (z >>> 31);
|
|
|
784 |
}
|
|
|
785 |
|
|
|
786 |
/**
|
|
|
787 |
* Computes Doug Lea's 64-bit mixing function.
|
|
|
788 |
* This is a 64-bit hashing function with excellent avalanche statistics.
|
|
|
789 |
* It has the advantages of using the same multiplicative constant twice
|
|
|
790 |
* and of using only 32-bit shifts.
|
|
|
791 |
*
|
|
|
792 |
* Note that if the argument {@code z} is 0, the result is 0.
|
|
|
793 |
*
|
|
|
794 |
* @param z any long value
|
|
|
795 |
*
|
|
|
796 |
* @return the result of hashing z
|
|
|
797 |
*/
|
|
|
798 |
public static long mixLea64(long z) {
|
|
|
799 |
z = (z ^ (z >>> 32)) * 0xdaba0b6eb09322e3L;
|
|
|
800 |
z = (z ^ (z >>> 32)) * 0xdaba0b6eb09322e3L;
|
|
|
801 |
return z ^ (z >>> 32);
|
|
|
802 |
}
|
|
|
803 |
|
|
|
804 |
/**
|
|
|
805 |
* Computes the 32-bit mixing function for MurmurHash3.
|
|
|
806 |
* This is a 32-bit hashing function with excellent avalanche statistics.
|
|
|
807 |
* https://github.com/aappleby/smhasher/wiki/MurmurHash3
|
|
|
808 |
*
|
|
|
809 |
* Note that if the argument {@code z} is 0, the result is 0.
|
|
|
810 |
*
|
|
|
811 |
* @param z any long value
|
|
|
812 |
*
|
|
|
813 |
* @return the result of hashing z
|
|
|
814 |
*/
|
|
|
815 |
public static int mixMurmur32(int z) {
|
|
|
816 |
z = (z ^ (z >>> 16)) * 0x85ebca6b;
|
|
|
817 |
z = (z ^ (z >>> 13)) * 0xc2b2ae35;
|
|
|
818 |
return z ^ (z >>> 16);
|
|
|
819 |
}
|
|
|
820 |
|
|
|
821 |
/**
|
|
|
822 |
* Computes Doug Lea's 32-bit mixing function.
|
|
|
823 |
* This is a 32-bit hashing function with excellent avalanche statistics.
|
|
|
824 |
* It has the advantages of using the same multiplicative constant twice
|
|
|
825 |
* and of using only 16-bit shifts.
|
|
|
826 |
*
|
|
|
827 |
* Note that if the argument {@code z} is 0, the result is 0.
|
|
|
828 |
*
|
|
|
829 |
* @param z any long value
|
|
|
830 |
*
|
|
|
831 |
* @return the result of hashing z
|
|
|
832 |
*/
|
|
|
833 |
public static int mixLea32(int z) {
|
|
|
834 |
z = (z ^ (z >>> 16)) * 0xd36d884b;
|
|
|
835 |
z = (z ^ (z >>> 16)) * 0xd36d884b;
|
|
|
836 |
return z ^ (z >>> 16);
|
|
|
837 |
}
|
|
|
838 |
|
|
|
839 |
// Non-public (package only) support for spliterators needed by AbstractSplittableGenerator
|
|
|
840 |
// and AbstractArbitrarilyJumpableGenerator and AbstractSharedGenerator
|
|
|
841 |
|
|
|
842 |
/**
|
|
|
843 |
* Base class for making Spliterator classes for streams of randomly chosen values.
|
|
|
844 |
*/
|
|
|
845 |
public abstract static class RandomSpliterator {
|
|
|
846 |
|
|
|
847 |
/** low range value */
|
|
|
848 |
public long index;
|
|
|
849 |
|
|
|
850 |
/** high range value */
|
|
|
851 |
public final long fence;
|
|
|
852 |
|
|
|
853 |
/**
|
|
|
854 |
* Constructor
|
|
|
855 |
*
|
|
|
856 |
* @param index low range value
|
|
|
857 |
* @param fence high range value
|
|
|
858 |
*/
|
|
|
859 |
public RandomSpliterator(long index, long fence) {
|
|
|
860 |
this.index = index; this.fence = fence;
|
|
|
861 |
}
|
|
|
862 |
|
|
|
863 |
/**
|
|
|
864 |
* Returns estimated size.
|
|
|
865 |
*
|
|
|
866 |
* @return estimated size
|
|
|
867 |
*/
|
|
|
868 |
public long estimateSize() {
|
|
|
869 |
return fence - index;
|
|
|
870 |
}
|
|
|
871 |
|
|
|
872 |
/**
|
|
|
873 |
* Returns characteristics.
|
|
|
874 |
*
|
|
|
875 |
* @return characteristics
|
|
|
876 |
*/
|
|
|
877 |
public int characteristics() {
|
|
|
878 |
return (Spliterator.SIZED | Spliterator.SUBSIZED |
|
|
|
879 |
Spliterator.NONNULL | Spliterator.IMMUTABLE);
|
|
|
880 |
}
|
|
|
881 |
}
|
|
|
882 |
|
|
|
883 |
|
|
|
884 |
/*
|
|
|
885 |
* Implementation support for nextExponential() and nextGaussian() methods of RandomGenerator.
|
|
|
886 |
*
|
|
|
887 |
* Each is implemented using McFarland's fast modified ziggurat algorithm (largely
|
|
|
888 |
* table-driven, with rare cases handled by computation and rejection sampling).
|
|
|
889 |
* Walker's alias method for sampling a discrete distribution also plays a role.
|
|
|
890 |
*
|
|
|
891 |
* The tables themselves, as well as a number of associated parameters, are defined
|
|
|
892 |
* in class java.util.DoubleZigguratTables, which is automatically generated by the
|
|
|
893 |
* program create_ziggurat_tables.c (which takes only a few seconds to run).
|
|
|
894 |
*
|
|
|
895 |
* For more information about the algorithms, see these articles:
|
|
|
896 |
*
|
|
|
897 |
* Christopher D. McFarland. 2016 (published online 24 Jun 2015). A modified ziggurat
|
|
|
898 |
* algorithm for generating exponentially and normally distributed pseudorandom numbers.
|
|
|
899 |
* Journal of Statistical Computation and Simulation 86 (7), pages 1281-1294.
|
|
|
900 |
* https://www.tandfonline.com/doi/abs/10.1080/00949655.2015.1060234
|
|
|
901 |
* Also at https://arxiv.org/abs/1403.6870 (26 March 2014).
|
|
|
902 |
*
|
|
|
903 |
* Alastair J. Walker. 1977. An efficient method for generating discrete random
|
|
|
904 |
* variables with general distributions. ACM Trans. Math. Software 3, 3
|
|
|
905 |
* (September 1977), 253-256. DOI: https://doi.org/10.1145/355744.355749
|
|
|
906 |
*
|
|
|
907 |
* Certain details of these algorithms depend critically on the quality of the
|
|
|
908 |
* low-order bits delivered by NextLong(). These algorithms should not be used
|
|
|
909 |
* with RNG algorithms (such as a simple Linear Congruential Generator) whose
|
|
|
910 |
* low-order output bits do not have good statistical quality.
|
|
|
911 |
*/
|
|
|
912 |
|
|
|
913 |
// Implementation support for nextExponential()
|
|
|
914 |
|
|
|
915 |
static double computeNextExponential(RandomGenerator rng) {
|
|
|
916 |
long U1 = rng.nextLong();
|
|
|
917 |
// Experimentation on a variety of machines indicates that it is overall much faster
|
|
|
918 |
// to do the following & and < operations on longs rather than first cast U1 to int
|
|
|
919 |
// (but then we need to cast to int before doing the array indexing operation).
|
|
|
920 |
long i = U1 & DoubleZigguratTables.exponentialLayerMask;
|
|
|
921 |
if (i < DoubleZigguratTables.exponentialNumberOfLayers) {
|
|
|
922 |
// This is the fast path (occurring more than 98% of the time). Make an early exit.
|
|
|
923 |
return DoubleZigguratTables.exponentialX[(int)i] * (U1 >>> 1);
|
|
|
924 |
}
|
|
|
925 |
// We didn't use the upper part of U1 after all. We'll be able to use it later.
|
|
|
926 |
|
|
|
927 |
for (double extra = 0.0; ; ) {
|
|
|
928 |
// Use Walker's alias method to sample an (unsigned) integer j from a discrete
|
|
|
929 |
// probability distribution that includes the tail and all the ziggurat overhangs;
|
|
|
930 |
// j will be less than DoubleZigguratTables.exponentialNumberOfLayers + 1.
|
|
|
931 |
long UA = rng.nextLong();
|
|
|
932 |
int j = (int)UA & DoubleZigguratTables.exponentialAliasMask;
|
|
|
933 |
if (UA >= DoubleZigguratTables.exponentialAliasThreshold[j]) {
|
|
|
934 |
j = DoubleZigguratTables.exponentialAliasMap[j] &
|
|
|
935 |
DoubleZigguratTables.exponentialSignCorrectionMask;
|
|
|
936 |
}
|
|
|
937 |
if (j > 0) { // Sample overhang j
|
|
|
938 |
// For the exponential distribution, every overhang is convex.
|
|
|
939 |
final double[] X = DoubleZigguratTables.exponentialX;
|
|
|
940 |
final double[] Y = DoubleZigguratTables.exponentialY;
|
|
|
941 |
for (;; U1 = (rng.nextLong() >>> 1)) {
|
|
|
942 |
long U2 = (rng.nextLong() >>> 1);
|
|
|
943 |
// Compute the actual x-coordinate of the randomly chosen point.
|
|
|
944 |
double x = (X[j] * 0x1.0p63) + ((X[j-1] - X[j]) * (double)U1);
|
|
|
945 |
// Does the point lie below the curve?
|
|
|
946 |
long Udiff = U2 - U1;
|
|
|
947 |
if (Udiff < 0) {
|
|
|
948 |
// We picked a point in the upper-right triangle. None of those can be
|
|
|
949 |
// accepted. So remap the point into the lower-left triangle and try that.
|
|
|
950 |
// In effect, we swap U1 and U2, and invert the sign of Udiff.
|
|
|
951 |
Udiff = -Udiff;
|
|
|
952 |
U2 = U1;
|
|
|
953 |
U1 -= Udiff;
|
|
|
954 |
}
|
|
|
955 |
if (Udiff >= DoubleZigguratTables.exponentialConvexMargin) {
|
|
|
956 |
return x + extra; // The chosen point is way below the curve; accept it.
|
|
|
957 |
}
|
|
|
958 |
// Compute the actual y-coordinate of the randomly chosen point.
|
|
|
959 |
double y = (Y[j] * 0x1.0p63) + ((Y[j] - Y[j-1]) * (double)U2);
|
|
|
960 |
// Now see how that y-coordinate compares to the curve
|
|
|
961 |
if (y <= Math.exp(-x)) {
|
|
|
962 |
return x + extra; // The chosen point is below the curve; accept it.
|
|
|
963 |
}
|
|
|
964 |
// Otherwise, we reject this sample and have to try again.
|
|
|
965 |
}
|
|
|
966 |
}
|
|
|
967 |
// We are now committed to sampling from the tail. We could do a recursive call
|
|
|
968 |
// and then add X[0] but we save some time and stack space by using an iterative loop.
|
|
|
969 |
extra += DoubleZigguratTables.exponentialX0;
|
|
|
970 |
// This is like the first five lines of this method, but if it returns, it first adds "extra".
|
|
|
971 |
U1 = rng.nextLong();
|
|
|
972 |
i = U1 & DoubleZigguratTables.exponentialLayerMask;
|
|
|
973 |
if (i < DoubleZigguratTables.exponentialNumberOfLayers) {
|
|
|
974 |
return DoubleZigguratTables.exponentialX[(int)i] * (U1 >>> 1) + extra;
|
|
|
975 |
}
|
|
|
976 |
}
|
|
|
977 |
}
|
|
|
978 |
|
|
|
979 |
// Implementation support for nextGaussian()
|
|
|
980 |
|
|
|
981 |
static double computeNextGaussian(RandomGenerator rng) {
|
|
|
982 |
long U1 = rng.nextLong();
|
|
|
983 |
// Experimentation on a variety of machines indicates that it is overall much faster
|
|
|
984 |
// to do the following & and < operations on longs rather than first cast U1 to int
|
|
|
985 |
// (but then we need to cast to int before doing the array indexing operation).
|
|
|
986 |
long i = U1 & DoubleZigguratTables.normalLayerMask;
|
|
|
987 |
|
|
|
988 |
if (i < DoubleZigguratTables.normalNumberOfLayers) {
|
|
|
989 |
// This is the fast path (occurring more than 98% of the time). Make an early exit.
|
|
|
990 |
return DoubleZigguratTables.normalX[(int)i] * U1; // Note that the sign bit of U1 is used here.
|
|
|
991 |
}
|
|
|
992 |
// We didn't use the upper part of U1 after all.
|
|
|
993 |
// Pull U1 apart into a sign bit and a 63-bit value for later use.
|
|
|
994 |
double signBit = (U1 >= 0) ? 1.0 : -1.0;
|
|
|
995 |
U1 = (U1 << 1) >>> 1;
|
|
|
996 |
|
|
|
997 |
// Use Walker's alias method to sample an (unsigned) integer j from a discrete
|
|
|
998 |
// probability distribution that includes the tail and all the ziggurat overhangs;
|
|
|
999 |
// j will be less than DoubleZigguratTables.normalNumberOfLayers + 1.
|
|
|
1000 |
long UA = rng.nextLong();
|
|
|
1001 |
int j = (int)UA & DoubleZigguratTables.normalAliasMask;
|
|
|
1002 |
if (UA >= DoubleZigguratTables.normalAliasThreshold[j]) {
|
|
|
1003 |
j = DoubleZigguratTables.normalAliasMap[j] & DoubleZigguratTables.normalSignCorrectionMask;
|
|
|
1004 |
}
|
|
|
1005 |
|
|
|
1006 |
double x;
|
|
|
1007 |
// Now the goal is to choose the result, which will be multiplied by signBit just before return.
|
|
|
1008 |
|
|
|
1009 |
// There are four kinds of overhangs:
|
|
|
1010 |
//
|
|
|
1011 |
// j == 0 : Sample from tail
|
|
|
1012 |
// 0 < j < normalInflectionIndex : Overhang is convex; can reject upper-right triangle
|
|
|
1013 |
// j == normalInflectionIndex : Overhang includes the inflection point
|
|
|
1014 |
// j > normalInflectionIndex : Overhang is concave; can accept point in lower-left triangle
|
|
|
1015 |
//
|
|
|
1016 |
// Choose one of four loops to compute x, each specialized for a specific kind of overhang.
|
|
|
1017 |
// Conditional statements are arranged such that the more likely outcomes are first.
|
|
|
1018 |
|
|
|
1019 |
// In the three cases other than the tail case:
|
|
|
1020 |
// U1 represents a fraction (scaled by 2**63) of the width of rectangle measured from the left.
|
|
|
1021 |
// U2 represents a fraction (scaled by 2**63) of the height of rectangle measured from the top.
|
|
|
1022 |
// Together they indicate a randomly chosen point within the rectangle.
|
|
|
1023 |
|
|
|
1024 |
final double[] X = DoubleZigguratTables.normalX;
|
|
|
1025 |
final double[] Y = DoubleZigguratTables.normalY;
|
|
|
1026 |
if (j > DoubleZigguratTables.normalInflectionIndex) { // Concave overhang
|
|
|
1027 |
for (;; U1 = (rng.nextLong() >>> 1)) {
|
|
|
1028 |
long U2 = (rng.nextLong() >>> 1);
|
|
|
1029 |
// Compute the actual x-coordinate of the randomly chosen point.
|
|
|
1030 |
x = (X[j] * 0x1.0p63) + ((X[j-1] - X[j]) * (double)U1);
|
|
|
1031 |
// Does the point lie below the curve?
|
|
|
1032 |
long Udiff = U2 - U1;
|
|
|
1033 |
if (Udiff >= 0) {
|
|
|
1034 |
break; // The chosen point is in the lower-left triangle; accept it.
|
|
|
1035 |
}
|
|
|
1036 |
if (Udiff <= -DoubleZigguratTables.normalConcaveMargin) {
|
|
|
1037 |
continue; // The chosen point is way above the curve; reject it.
|
|
|
1038 |
}
|
|
|
1039 |
// Compute the actual y-coordinate of the randomly chosen point.
|
|
|
1040 |
double y = (Y[j] * 0x1.0p63) + ((Y[j] - Y[j-1]) * (double)U2);
|
|
|
1041 |
// Now see how that y-coordinate compares to the curve
|
|
|
1042 |
if (y <= Math.exp(-0.5*x*x)) {
|
|
|
1043 |
break; // The chosen point is below the curve; accept it.
|
|
|
1044 |
}
|
|
|
1045 |
// Otherwise, we reject this sample and have to try again.
|
|
|
1046 |
}
|
|
|
1047 |
} else if (j == 0) { // Tail
|
|
|
1048 |
// Tail-sampling method of Marsaglia and Tsang. See any one of:
|
|
|
1049 |
// Marsaglia and Tsang. 1984. A fast, easily implemented method for sampling from decreasing
|
|
|
1050 |
// or symmetric unimodal density functions. SIAM J. Sci. Stat. Comput. 5, 349-359.
|
|
|
1051 |
// Marsaglia and Tsang. 1998. The Monty Python method for generating random variables.
|
|
|
1052 |
// ACM Trans. Math. Softw. 24, 3 (September 1998), 341-350. See page 342, step (4).
|
|
|
1053 |
// http://doi.org/10.1145/292395.292453
|
|
|
1054 |
// Thomas, Luk, Leong, and Villasenor. 2007. Gaussian random number generators.
|
|
|
1055 |
// ACM Comput. Surv. 39, 4, Article 11 (November 2007). See Algorithm 16.
|
|
|
1056 |
// http://doi.org/10.1145/1287620.1287622
|
|
|
1057 |
// Compute two separate random exponential samples and then compare them in certain way.
|
|
|
1058 |
do {
|
|
|
1059 |
x = (1.0 / DoubleZigguratTables.normalX0) * computeNextExponential(rng);
|
|
|
1060 |
} while (computeNextExponential(rng) < 0.5*x*x);
|
|
|
1061 |
x += DoubleZigguratTables.normalX0;
|
|
|
1062 |
} else if (j < DoubleZigguratTables.normalInflectionIndex) { // Convex overhang
|
|
|
1063 |
for (;; U1 = (rng.nextLong() >>> 1)) {
|
|
|
1064 |
long U2 = (rng.nextLong() >>> 1);
|
|
|
1065 |
// Compute the actual x-coordinate of the randomly chosen point.
|
|
|
1066 |
x = (X[j] * 0x1.0p63) + ((X[j-1] - X[j]) * (double)U1);
|
|
|
1067 |
// Does the point lie below the curve?
|
|
|
1068 |
long Udiff = U2 - U1;
|
|
|
1069 |
if (Udiff < 0) {
|
|
|
1070 |
// We picked a point in the upper-right triangle. None of those can be accepted.
|
|
|
1071 |
// So remap the point into the lower-left triangle and try that.
|
|
|
1072 |
// In effect, we swap U1 and U2, and invert the sign of Udiff.
|
|
|
1073 |
Udiff = -Udiff;
|
|
|
1074 |
U2 = U1;
|
|
|
1075 |
U1 -= Udiff;
|
|
|
1076 |
}
|
|
|
1077 |
if (Udiff >= DoubleZigguratTables.normalConvexMargin) {
|
|
|
1078 |
break; // The chosen point is way below the curve; accept it.
|
|
|
1079 |
}
|
|
|
1080 |
// Compute the actual y-coordinate of the randomly chosen point.
|
|
|
1081 |
double y = (Y[j] * 0x1.0p63) + ((Y[j] - Y[j-1]) * (double)U2);
|
|
|
1082 |
// Now see how that y-coordinate compares to the curve
|
|
|
1083 |
if (y <= Math.exp(-0.5*x*x)) break; // The chosen point is below the curve; accept it.
|
|
|
1084 |
// Otherwise, we reject this sample and have to try again.
|
|
|
1085 |
}
|
|
|
1086 |
} else {
|
|
|
1087 |
// The overhang includes the inflection point, so the curve is both convex and concave
|
|
|
1088 |
for (;; U1 = (rng.nextLong() >>> 1)) {
|
|
|
1089 |
long U2 = (rng.nextLong() >>> 1);
|
|
|
1090 |
// Compute the actual x-coordinate of the randomly chosen point.
|
|
|
1091 |
x = (X[j] * 0x1.0p63) + ((X[j-1] - X[j]) * (double)U1);
|
|
|
1092 |
// Does the point lie below the curve?
|
|
|
1093 |
long Udiff = U2 - U1;
|
|
|
1094 |
if (Udiff >= DoubleZigguratTables.normalConvexMargin) {
|
|
|
1095 |
break; // The chosen point is way below the curve; accept it.
|
|
|
1096 |
}
|
|
|
1097 |
if (Udiff <= -DoubleZigguratTables.normalConcaveMargin) {
|
|
|
1098 |
continue; // The chosen point is way above the curve; reject it.
|
|
|
1099 |
}
|
|
|
1100 |
// Compute the actual y-coordinate of the randomly chosen point.
|
|
|
1101 |
double y = (Y[j] * 0x1.0p63) + ((Y[j] - Y[j-1]) * (double)U2);
|
|
|
1102 |
// Now see how that y-coordinate compares to the curve
|
|
|
1103 |
if (y <= Math.exp(-0.5*x*x)) {
|
|
|
1104 |
break; // The chosen point is below the curve; accept it.
|
|
|
1105 |
}
|
|
|
1106 |
// Otherwise, we reject this sample and have to try again.
|
|
|
1107 |
}
|
|
|
1108 |
}
|
|
|
1109 |
return signBit*x;
|
|
|
1110 |
}
|
|
|
1111 |
|
|
|
1112 |
/**
|
|
|
1113 |
* This class overrides the stream-producing methods (such as {@code ints()})
|
|
|
1114 |
* in class {@link AbstractGenerator} to provide {@link Spliterator}-based
|
|
|
1115 |
* implmentations that support potentially parallel execution.
|
|
|
1116 |
*
|
|
|
1117 |
* To implement a pseudorandom number generator, the programmer needs
|
|
|
1118 |
* only to extend this class and provide implementations for the methods
|
|
|
1119 |
* {@code nextInt()}, {@code nextLong()}, {@code makeIntsSpliterator},
|
|
|
1120 |
* {@code makeLongsSpliterator}, and {@code makeDoublesSpliterator}.
|
|
|
1121 |
*
|
|
|
1122 |
* This class is not public; it provides shared code to the public
|
|
|
1123 |
* classes {@link AbstractSplittableGenerator}, {@link AbstractSharedGenerator},
|
|
|
1124 |
* and {@link AbstractArbitrarilyJumpableGenerator}.
|
|
|
1125 |
*
|
|
|
1126 |
* @since 14
|
|
|
1127 |
*/
|
|
|
1128 |
public abstract static class AbstractSpliteratorGenerator implements RandomGenerator {
|
|
|
1129 |
/*
|
|
|
1130 |
* Implementation Overview.
|
|
|
1131 |
*
|
|
|
1132 |
* This class provides most of the "user API" methods needed to
|
|
|
1133 |
* satisfy the interface RandomGenerator. An implementation of this
|
|
|
1134 |
* interface need only extend this class and provide implementations
|
|
|
1135 |
* of six methods: nextInt, nextLong, and nextDouble (the versions
|
|
|
1136 |
* that take no arguments) and makeIntsSpliterator,
|
|
|
1137 |
* makeLongsSpliterator, and makeDoublesSpliterator.
|
|
|
1138 |
*
|
|
|
1139 |
* File organization: First the non-public abstract methods needed
|
|
|
1140 |
* to create spliterators, then the main public methods.
|
|
|
1141 |
*/
|
|
|
1142 |
|
|
|
1143 |
/**
|
|
|
1144 |
* Create an instance of {@link Spliterator.OfInt} that for each traversal position
|
|
|
1145 |
* between the specified index (inclusive) and the specified fence (exclusive) generates
|
|
|
1146 |
* a pseudorandomly chosen {@code int} value between the specified origin (inclusive) and
|
|
|
1147 |
* the specified bound (exclusive).
|
|
|
1148 |
*
|
|
|
1149 |
* @param index the (inclusive) lower bound on traversal positions
|
|
|
1150 |
* @param fence the (exclusive) upper bound on traversal positions
|
|
|
1151 |
* @param origin the (inclusive) lower bound on the pseudorandom values to be generated
|
|
|
1152 |
* @param bound the (exclusive) upper bound on the pseudorandom values to be generated
|
|
|
1153 |
* @return an instance of {@link Spliterator.OfInt}
|
|
|
1154 |
*/
|
|
|
1155 |
public abstract Spliterator.OfInt makeIntsSpliterator(long index, long fence, int origin, int bound);
|
|
|
1156 |
|
|
|
1157 |
/**
|
|
|
1158 |
* Create an instance of {@link Spliterator.OfLong} that for each traversal position
|
|
|
1159 |
* between the specified index (inclusive) and the specified fence (exclusive) generates
|
|
|
1160 |
* a pseudorandomly chosen {@code long} value between the specified origin (inclusive) and
|
|
|
1161 |
* the specified bound (exclusive).
|
|
|
1162 |
*
|
|
|
1163 |
* @param index the (inclusive) lower bound on traversal positions
|
|
|
1164 |
* @param fence the (exclusive) upper bound on traversal positions
|
|
|
1165 |
* @param origin the (inclusive) lower bound on the pseudorandom values to be generated
|
|
|
1166 |
* @param bound the (exclusive) upper bound on the pseudorandom values to be generated
|
|
|
1167 |
* @return an instance of {@link Spliterator.OfLong}
|
|
|
1168 |
*/
|
|
|
1169 |
public abstract Spliterator.OfLong makeLongsSpliterator(long index, long fence, long origin, long bound);
|
|
|
1170 |
|
|
|
1171 |
/**
|
|
|
1172 |
* Create an instance of {@link Spliterator.OfDouble} that for each traversal position
|
|
|
1173 |
* between the specified index (inclusive) and the specified fence (exclusive) generates
|
|
|
1174 |
* a pseudorandomly chosen {@code double} value between the specified origin (inclusive) and
|
|
|
1175 |
* the specified bound (exclusive).
|
|
|
1176 |
*
|
|
|
1177 |
* @param index the (inclusive) lower bound on traversal positions
|
|
|
1178 |
* @param fence the (exclusive) upper bound on traversal positions
|
|
|
1179 |
* @param origin the (inclusive) lower bound on the pseudorandom values to be generated
|
|
|
1180 |
* @param bound the (exclusive) upper bound on the pseudorandom values to be generated
|
|
|
1181 |
* @return an instance of {@link Spliterator.OfDouble}
|
|
|
1182 |
*/
|
|
|
1183 |
public abstract Spliterator.OfDouble makeDoublesSpliterator(long index, long fence, double origin, double bound);
|
|
|
1184 |
|
|
|
1185 |
/* ---------------- public methods ---------------- */
|
|
|
1186 |
|
|
|
1187 |
// stream methods, coded in a way intended to better isolate for
|
|
|
1188 |
// maintenance purposes the small differences across forms.
|
|
|
1189 |
|
|
|
1190 |
private static IntStream intStream(Spliterator.OfInt srng) {
|
|
|
1191 |
return StreamSupport.intStream(srng, false);
|
|
|
1192 |
}
|
|
|
1193 |
|
|
|
1194 |
private static LongStream longStream(Spliterator.OfLong srng) {
|
|
|
1195 |
return StreamSupport.longStream(srng, false);
|
|
|
1196 |
}
|
|
|
1197 |
|
|
|
1198 |
private static DoubleStream doubleStream(Spliterator.OfDouble srng) {
|
|
|
1199 |
return StreamSupport.doubleStream(srng, false);
|
|
|
1200 |
}
|
|
|
1201 |
|
|
|
1202 |
/**
|
|
|
1203 |
* Returns a stream producing the given {@code streamSize} number of pseudorandom {@code int}
|
|
|
1204 |
* values from this generator and/or one split from it.
|
|
|
1205 |
*
|
|
|
1206 |
* @param streamSize the number of values to generate
|
|
|
1207 |
*
|
|
|
1208 |
* @return a stream of pseudorandom {@code int} values
|
|
|
1209 |
*
|
|
|
1210 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero
|
|
|
1211 |
*/
|
|
|
1212 |
public IntStream ints(long streamSize) {
|
|
|
1213 |
RandomSupport.checkStreamSize(streamSize);
|
|
|
1214 |
return intStream(makeIntsSpliterator(0L, streamSize, Integer.MAX_VALUE, 0));
|
|
|
1215 |
}
|
|
|
1216 |
|
|
|
1217 |
/**
|
|
|
1218 |
* Returns an effectively unlimited stream of pseudorandomly chosen
|
|
|
1219 |
* {@code int} values.
|
|
|
1220 |
*
|
|
|
1221 |
* @implNote The implementation of this method is effectively
|
|
|
1222 |
* equivalent to {@code ints(Long.MAX_VALUE)}.
|
|
|
1223 |
*
|
|
|
1224 |
* @return a stream of pseudorandomly chosen {@code int} values
|
|
|
1225 |
*/
|
|
|
1226 |
|
|
|
1227 |
public IntStream ints() {
|
|
|
1228 |
return intStream(makeIntsSpliterator(0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0));
|
|
|
1229 |
}
|
|
|
1230 |
|
|
|
1231 |
/**
|
|
|
1232 |
* Returns a stream producing the given {@code streamSize} number of pseudorandom {@code int}
|
|
|
1233 |
* values from this generator and/or one split from it; each value conforms to the given origin
|
|
|
1234 |
* (inclusive) and bound (exclusive).
|
|
|
1235 |
*
|
|
|
1236 |
* @param streamSize the number of values to generate
|
|
|
1237 |
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
|
1238 |
* @param randomNumberBound the bound (exclusive) of each random value
|
|
|
1239 |
*
|
|
|
1240 |
* @return a stream of pseudorandom {@code int} values, each with the given origin (inclusive)
|
|
|
1241 |
* and bound (exclusive)
|
|
|
1242 |
*
|
|
|
1243 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero, or {@code
|
|
|
1244 |
* randomNumberOrigin} is greater than or equal to {@code
|
|
|
1245 |
* randomNumberBound}
|
|
|
1246 |
*/
|
|
|
1247 |
public IntStream ints(long streamSize, int randomNumberOrigin, int randomNumberBound) {
|
|
|
1248 |
RandomSupport.checkStreamSize(streamSize);
|
|
|
1249 |
RandomSupport.checkRange(randomNumberOrigin, randomNumberBound);
|
|
|
1250 |
return intStream(makeIntsSpliterator(0L, streamSize, randomNumberOrigin, randomNumberBound));
|
|
|
1251 |
}
|
|
|
1252 |
|
|
|
1253 |
/**
|
|
|
1254 |
* Returns an effectively unlimited stream of pseudorandom {@code int} values from this
|
|
|
1255 |
* generator and/or one split from it; each value conforms to the given origin (inclusive) and
|
|
|
1256 |
* bound (exclusive).
|
|
|
1257 |
*
|
|
|
1258 |
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
|
1259 |
* @param randomNumberBound the bound (exclusive) of each random value
|
|
|
1260 |
*
|
|
|
1261 |
* @return a stream of pseudorandom {@code int} values, each with the given origin (inclusive)
|
|
|
1262 |
* and bound (exclusive)
|
|
|
1263 |
*
|
|
|
1264 |
* @throws IllegalArgumentException if {@code randomNumberOrigin} is greater than or equal to
|
|
|
1265 |
* {@code randomNumberBound}
|
|
|
1266 |
*
|
|
|
1267 |
* @implNote This method is implemented to be equivalent to {@code ints(Long.MAX_VALUE,
|
|
|
1268 |
* randomNumberOrigin, randomNumberBound)}.
|
|
|
1269 |
*/
|
|
|
1270 |
public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
|
|
|
1271 |
RandomSupport.checkRange(randomNumberOrigin, randomNumberBound);
|
|
|
1272 |
return intStream(makeIntsSpliterator(0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound));
|
|
|
1273 |
}
|
|
|
1274 |
|
|
|
1275 |
/**
|
|
|
1276 |
* Returns a stream producing the given {@code streamSize} number of pseudorandom {@code long}
|
|
|
1277 |
* values from this generator and/or one split from it.
|
|
|
1278 |
*
|
|
|
1279 |
* @param streamSize the number of values to generate
|
|
|
1280 |
*
|
|
|
1281 |
* @return a stream of pseudorandom {@code long} values
|
|
|
1282 |
*
|
|
|
1283 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero
|
|
|
1284 |
*/
|
|
|
1285 |
public LongStream longs(long streamSize) {
|
|
|
1286 |
RandomSupport.checkStreamSize(streamSize);
|
|
|
1287 |
return longStream(makeLongsSpliterator(0L, streamSize, Long.MAX_VALUE, 0L));
|
|
|
1288 |
}
|
|
|
1289 |
|
|
|
1290 |
/**
|
|
|
1291 |
* Returns an effectively unlimited stream of pseudorandom {@code long} values from this
|
|
|
1292 |
* generator and/or one split from it.
|
|
|
1293 |
*
|
|
|
1294 |
* @return a stream of pseudorandom {@code long} values
|
|
|
1295 |
*
|
|
|
1296 |
* @implNote This method is implemented to be equivalent to {@code
|
|
|
1297 |
* longs(Long.MAX_VALUE)}.
|
|
|
1298 |
*/
|
|
|
1299 |
public LongStream longs() {
|
|
|
1300 |
return longStream(makeLongsSpliterator(0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L));
|
|
|
1301 |
}
|
|
|
1302 |
|
|
|
1303 |
/**
|
|
|
1304 |
* Returns a stream producing the given {@code streamSize} number of pseudorandom {@code long}
|
|
|
1305 |
* values from this generator and/or one split from it; each value conforms to the given origin
|
|
|
1306 |
* (inclusive) and bound (exclusive).
|
|
|
1307 |
*
|
|
|
1308 |
* @param streamSize the number of values to generate
|
|
|
1309 |
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
|
1310 |
* @param randomNumberBound the bound (exclusive) of each random value
|
|
|
1311 |
*
|
|
|
1312 |
* @return a stream of pseudorandom {@code long} values, each with the given origin (inclusive)
|
|
|
1313 |
* and bound (exclusive)
|
|
|
1314 |
*
|
|
|
1315 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero, or {@code
|
|
|
1316 |
* randomNumberOrigin} is greater than or equal to {@code
|
|
|
1317 |
* randomNumberBound}
|
|
|
1318 |
*/
|
|
|
1319 |
public LongStream longs(long streamSize, long randomNumberOrigin,
|
|
|
1320 |
long randomNumberBound) {
|
|
|
1321 |
RandomSupport.checkStreamSize(streamSize);
|
|
|
1322 |
RandomSupport.checkRange(randomNumberOrigin, randomNumberBound);
|
|
|
1323 |
return longStream(makeLongsSpliterator(0L, streamSize, randomNumberOrigin, randomNumberBound));
|
|
|
1324 |
}
|
|
|
1325 |
|
|
|
1326 |
/**
|
|
|
1327 |
* Returns an effectively unlimited stream of pseudorandom {@code long} values from this
|
|
|
1328 |
* generator and/or one split from it; each value conforms to the given origin (inclusive) and
|
|
|
1329 |
* bound (exclusive).
|
|
|
1330 |
*
|
|
|
1331 |
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
|
1332 |
* @param randomNumberBound the bound (exclusive) of each random value
|
|
|
1333 |
*
|
|
|
1334 |
* @return a stream of pseudorandom {@code long} values, each with the given origin (inclusive)
|
|
|
1335 |
* and bound (exclusive)
|
|
|
1336 |
*
|
|
|
1337 |
* @throws IllegalArgumentException if {@code randomNumberOrigin} is greater than or equal to
|
|
|
1338 |
* {@code randomNumberBound}
|
|
|
1339 |
*
|
|
|
1340 |
* @implNote This method is implemented to be equivalent to {@code longs(Long.MAX_VALUE,
|
|
|
1341 |
* randomNumberOrigin, randomNumberBound)}.
|
|
|
1342 |
*/
|
|
|
1343 |
public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
|
|
|
1344 |
RandomSupport.checkRange(randomNumberOrigin, randomNumberBound);
|
|
|
1345 |
return StreamSupport.longStream
|
|
|
1346 |
(makeLongsSpliterator(0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
|
|
|
1347 |
false);
|
|
|
1348 |
}
|
|
|
1349 |
|
|
|
1350 |
/**
|
|
|
1351 |
* Returns a stream producing the given {@code streamSize} number of pseudorandom {@code double}
|
|
|
1352 |
* values from this generator and/or one split from it; each value is between zero (inclusive)
|
|
|
1353 |
* and one (exclusive).
|
|
|
1354 |
*
|
|
|
1355 |
* @param streamSize the number of values to generate
|
|
|
1356 |
*
|
|
|
1357 |
* @return a stream of {@code double} values
|
|
|
1358 |
*
|
|
|
1359 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero
|
|
|
1360 |
*/
|
|
|
1361 |
public DoubleStream doubles(long streamSize) {
|
|
|
1362 |
RandomSupport.checkStreamSize(streamSize);
|
|
|
1363 |
return doubleStream(makeDoublesSpliterator(0L, streamSize, Double.MAX_VALUE, 0.0));
|
|
|
1364 |
}
|
|
|
1365 |
|
|
|
1366 |
/**
|
|
|
1367 |
* Returns an effectively unlimited stream of pseudorandom {@code double} values from this
|
|
|
1368 |
* generator and/or one split from it; each value is between zero (inclusive) and one
|
|
|
1369 |
* (exclusive).
|
|
|
1370 |
*
|
|
|
1371 |
* @return a stream of pseudorandom {@code double} values
|
|
|
1372 |
*
|
|
|
1373 |
* @implNote This method is implemented to be equivalent to {@code
|
|
|
1374 |
* doubles(Long.MAX_VALUE)}.
|
|
|
1375 |
*/
|
|
|
1376 |
public DoubleStream doubles() {
|
|
|
1377 |
return doubleStream(makeDoublesSpliterator(0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0));
|
|
|
1378 |
}
|
|
|
1379 |
|
|
|
1380 |
/**
|
|
|
1381 |
* Returns a stream producing the given {@code streamSize} number of pseudorandom {@code double}
|
|
|
1382 |
* values from this generator and/or one split from it; each value conforms to the given origin
|
|
|
1383 |
* (inclusive) and bound (exclusive).
|
|
|
1384 |
*
|
|
|
1385 |
* @param streamSize the number of values to generate
|
|
|
1386 |
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
|
1387 |
* @param randomNumberBound the bound (exclusive) of each random value
|
|
|
1388 |
*
|
|
|
1389 |
* @return a stream of pseudorandom {@code double} values, each with the given origin
|
|
|
1390 |
* (inclusive) and bound (exclusive)
|
|
|
1391 |
*
|
|
|
1392 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero
|
|
|
1393 |
* @throws IllegalArgumentException if {@code randomNumberOrigin} is greater than or equal to
|
|
|
1394 |
* {@code randomNumberBound}
|
|
|
1395 |
*/
|
|
|
1396 |
public DoubleStream doubles(long streamSize, double randomNumberOrigin, double randomNumberBound) {
|
|
|
1397 |
RandomSupport.checkStreamSize(streamSize);
|
|
|
1398 |
RandomSupport.checkRange(randomNumberOrigin, randomNumberBound);
|
|
|
1399 |
return doubleStream(makeDoublesSpliterator(0L, streamSize, randomNumberOrigin, randomNumberBound));
|
|
|
1400 |
}
|
|
|
1401 |
|
|
|
1402 |
/**
|
|
|
1403 |
* Returns an effectively unlimited stream of pseudorandom {@code double} values from this
|
|
|
1404 |
* generator and/or one split from it; each value conforms to the given origin (inclusive) and
|
|
|
1405 |
* bound (exclusive).
|
|
|
1406 |
*
|
|
|
1407 |
* @param randomNumberOrigin the origin (inclusive) of each random value
|
|
|
1408 |
* @param randomNumberBound the bound (exclusive) of each random value
|
|
|
1409 |
*
|
|
|
1410 |
* @return a stream of pseudorandom {@code double} values, each with the given origin
|
|
|
1411 |
* (inclusive) and bound (exclusive)
|
|
|
1412 |
*
|
|
|
1413 |
* @throws IllegalArgumentException if {@code randomNumberOrigin} is greater than or equal to
|
|
|
1414 |
* {@code randomNumberBound}
|
|
|
1415 |
*
|
|
|
1416 |
* @implNote This method is implemented to be equivalent to {@code
|
|
|
1417 |
* doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}.
|
|
|
1418 |
*/
|
|
|
1419 |
public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
|
|
|
1420 |
RandomSupport.checkRange(randomNumberOrigin, randomNumberBound);
|
|
|
1421 |
return doubleStream(makeDoublesSpliterator(0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound));
|
|
|
1422 |
}
|
|
|
1423 |
|
|
|
1424 |
}
|
|
|
1425 |
|
|
|
1426 |
/**
|
|
|
1427 |
* This class provides much of the implementation of the
|
|
|
1428 |
* {@link ArbitrarilyJumpableGenerator} interface, to minimize the effort
|
|
|
1429 |
* required to implement that interface.
|
|
|
1430 |
*
|
|
|
1431 |
* To implement a pseudorandom number generator, the programmer needs
|
|
|
1432 |
* only to extend this class and provide implementations for the
|
|
|
1433 |
* methods {@link #nextInt()}, {@link #nextLong()}, {@link #copy()},
|
|
|
1434 |
* {@link #jump(double)}, {@link #jumpPowerOfTwo(int)},
|
|
|
1435 |
* {@link #defaultJumpDistance()}, and {@link #defaultLeapDistance()}.
|
|
|
1436 |
*
|
|
|
1437 |
* (If the pseudorandom number generator also has the ability to split,
|
|
|
1438 |
* then the programmer may wish to consider instead extending
|
|
|
1439 |
* {@link AbstractSplittableGenerator}.)
|
|
|
1440 |
*
|
|
|
1441 |
* The programmer should generally provide at least three constructors:
|
|
|
1442 |
* one that takes no arguments, one that accepts a {@code long}
|
|
|
1443 |
* seed value, and one that accepts an array of seed {@code byte} values.
|
|
|
1444 |
* This class provides a public {@code initialSeed()} method that may
|
|
|
1445 |
* be useful in initializing some static state from which to derive
|
|
|
1446 |
* defaults seeds for use by the no-argument constructor.
|
|
|
1447 |
*
|
|
|
1448 |
* For the stream methods (such as {@code ints()} and {@code splits()}),
|
|
|
1449 |
* this class provides {@link Spliterator}-based implementations that
|
|
|
1450 |
* allow parallel execution when appropriate. In this respect
|
|
|
1451 |
* {@link ArbitrarilyJumpableGenerator} differs from {@link JumpableGenerator},
|
|
|
1452 |
* which provides very simple implementations that produce
|
|
|
1453 |
* sequential streams only.
|
|
|
1454 |
*
|
|
|
1455 |
* <p>An implementation of the {@link AbstractArbitrarilyJumpableGenerator} class
|
|
|
1456 |
* must provide concrete definitions for the methods {@code nextInt()},
|
|
|
1457 |
* {@code nextLong}, {@code period()}, {@code copy()}, {@code jump(double)},
|
|
|
1458 |
* {@code defaultJumpDistance()}, and {@code defaultLeapDistance()}.
|
|
|
1459 |
* Default implementations are provided for all other methods.
|
|
|
1460 |
*
|
|
|
1461 |
* The documentation for each non-abstract method in this class
|
|
|
1462 |
* describes its implementation in detail. Each of these methods may
|
|
|
1463 |
* be overridden if the pseudorandom number generator being
|
|
|
1464 |
* implemented admits a more efficient implementation.
|
|
|
1465 |
*
|
|
|
1466 |
* @since 14
|
|
|
1467 |
*/
|
|
|
1468 |
public abstract static class AbstractArbitrarilyJumpableGenerator
|
|
|
1469 |
extends AbstractSpliteratorGenerator implements RandomGenerator.ArbitrarilyJumpableGenerator {
|
|
|
1470 |
|
|
|
1471 |
/*
|
|
|
1472 |
* Implementation Overview.
|
|
|
1473 |
*
|
|
|
1474 |
* This class provides most of the "user API" methods needed to satisfy
|
|
|
1475 |
* the interface ArbitrarilyJumpableGenerator. Most of these methods
|
|
|
1476 |
* are in turn inherited from AbstractGenerator and the non-public class
|
|
|
1477 |
* AbstractSpliteratorGenerator; this file implements four versions of the
|
|
|
1478 |
* jumps method and defines the spliterators necessary to support them.
|
|
|
1479 |
*
|
|
|
1480 |
* File organization: First the non-public methods needed by the class
|
|
|
1481 |
* AbstractSpliteratorGenerator, then the main public methods, followed by some
|
|
|
1482 |
* custom spliterator classes needed for stream methods.
|
|
|
1483 |
*/
|
|
|
1484 |
|
|
|
1485 |
// IllegalArgumentException messages
|
|
|
1486 |
static final String BadLogDistance = "logDistance must be non-negative";
|
|
|
1487 |
|
|
|
1488 |
// Methods required by class AbstractSpliteratorGenerator
|
|
|
1489 |
public Spliterator.OfInt makeIntsSpliterator(long index, long fence, int origin, int bound) {
|
|
|
1490 |
return new RandomIntsSpliterator(this, index, fence, origin, bound);
|
|
|
1491 |
}
|
|
|
1492 |
public Spliterator.OfLong makeLongsSpliterator(long index, long fence, long origin, long bound) {
|
|
|
1493 |
return new RandomLongsSpliterator(this, index, fence, origin, bound);
|
|
|
1494 |
}
|
|
|
1495 |
public Spliterator.OfDouble makeDoublesSpliterator(long index, long fence, double origin, double bound) {
|
|
|
1496 |
return new RandomDoublesSpliterator(this, index, fence, origin, bound);
|
|
|
1497 |
}
|
|
|
1498 |
|
|
|
1499 |
// Similar methods used by this class
|
|
|
1500 |
Spliterator<RandomGenerator> makeJumpsSpliterator(long index, long fence, double distance) {
|
|
|
1501 |
return new RandomJumpsSpliterator(this, index, fence, distance);
|
|
|
1502 |
}
|
|
|
1503 |
Spliterator<JumpableGenerator> makeLeapsSpliterator(long index, long fence, double distance) {
|
|
|
1504 |
return new RandomLeapsSpliterator(this, index, fence, distance);
|
|
|
1505 |
}
|
|
|
1506 |
Spliterator<ArbitrarilyJumpableGenerator> makeArbitraryJumpsSpliterator(long index, long fence, double distance) {
|
|
|
1507 |
return new RandomArbitraryJumpsSpliterator(this, index, fence, distance);
|
|
|
1508 |
}
|
|
|
1509 |
|
|
|
1510 |
/* ---------------- public methods ---------------- */
|
|
|
1511 |
|
|
|
1512 |
/**
|
|
|
1513 |
* Returns a new generator whose internal state is an exact copy
|
|
|
1514 |
* of this generator (therefore their future behavior should be
|
|
|
1515 |
* identical if subjected to the same series of operations).
|
|
|
1516 |
*
|
|
|
1517 |
* @return a new object that is a copy of this generator
|
|
|
1518 |
*/
|
|
|
1519 |
public abstract AbstractArbitrarilyJumpableGenerator copy();
|
|
|
1520 |
|
|
|
1521 |
// Stream methods for jumping
|
|
|
1522 |
|
|
|
1523 |
private static <T> Stream<T> stream(Spliterator<T> srng) {
|
|
|
1524 |
return StreamSupport.stream(srng, false);
|
|
|
1525 |
}
|
|
|
1526 |
|
|
|
1527 |
/**
|
|
|
1528 |
* Returns an effectively unlimited stream of new pseudorandom number generators, each of which
|
|
|
1529 |
* implements the {@link RandomGenerator} interface, produced by jumping copies of this
|
|
|
1530 |
* generator by different integer multiples of the default jump distance.
|
|
|
1531 |
*
|
|
|
1532 |
* @return a stream of objects that implement the {@link RandomGenerator} interface
|
|
|
1533 |
*
|
|
|
1534 |
* @implNote This method is implemented to be equivalent to {@code
|
|
|
1535 |
* jumps(Long.MAX_VALUE)}.
|
|
|
1536 |
*/
|
|
|
1537 |
public Stream<RandomGenerator> jumps() {
|
|
|
1538 |
return stream(makeJumpsSpliterator(0L, Long.MAX_VALUE, defaultJumpDistance()));
|
|
|
1539 |
}
|
|
|
1540 |
|
|
|
1541 |
/**
|
|
|
1542 |
* Returns a stream producing the given {@code streamSize} number of
|
|
|
1543 |
* new pseudorandom number generators, each of which implements the
|
|
|
1544 |
* {@link RandomGenerator} interface, produced by jumping copies of this generator
|
|
|
1545 |
* by different integer multiples of the default jump distance.
|
|
|
1546 |
*
|
|
|
1547 |
* @param streamSize the number of generators to generate
|
|
|
1548 |
*
|
|
|
1549 |
* @return a stream of objects that implement the {@link RandomGenerator} interface
|
|
|
1550 |
*
|
|
|
1551 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero
|
|
|
1552 |
*/
|
|
|
1553 |
public Stream<RandomGenerator> jumps(long streamSize) {
|
|
|
1554 |
RandomSupport.checkStreamSize(streamSize);
|
|
|
1555 |
return stream(makeJumpsSpliterator(0L, streamSize, defaultJumpDistance()));
|
|
|
1556 |
}
|
|
|
1557 |
|
|
|
1558 |
/**
|
|
|
1559 |
* Returns an effectively unlimited stream of new pseudorandom number generators, each of which
|
|
|
1560 |
* implements the {@link RandomGenerator} interface, produced by jumping copies of this
|
|
|
1561 |
* generator by different integer multiples of the specified jump distance.
|
|
|
1562 |
*
|
|
|
1563 |
* @param distance a distance to jump forward within the state cycle
|
|
|
1564 |
*
|
|
|
1565 |
* @return a stream of objects that implement the {@link RandomGenerator} interface
|
|
|
1566 |
*
|
|
|
1567 |
* @implNote This method is implemented to be equivalent to {@code
|
|
|
1568 |
* jumps(Long.MAX_VALUE)}.
|
|
|
1569 |
*/
|
|
|
1570 |
public Stream<ArbitrarilyJumpableGenerator> jumps(double distance) {
|
|
|
1571 |
return stream(makeArbitraryJumpsSpliterator(0L, Long.MAX_VALUE, distance));
|
|
|
1572 |
}
|
|
|
1573 |
|
|
|
1574 |
/**
|
|
|
1575 |
* Returns a stream producing the given {@code streamSize} number of new pseudorandom number
|
|
|
1576 |
* generators, each of which implements the {@link RandomGenerator} interface, produced by
|
|
|
1577 |
* jumping copies of this generator by different integer multiples of the specified jump
|
|
|
1578 |
* distance.
|
|
|
1579 |
*
|
|
|
1580 |
* @param streamSize the number of generators to generate
|
|
|
1581 |
* @param distance a distance to jump forward within the state cycle
|
|
|
1582 |
*
|
|
|
1583 |
* @return a stream of objects that implement the {@link RandomGenerator} interface
|
|
|
1584 |
*
|
|
|
1585 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero
|
|
|
1586 |
*/
|
|
|
1587 |
public Stream<ArbitrarilyJumpableGenerator> jumps(long streamSize, double distance) {
|
|
|
1588 |
RandomSupport.checkStreamSize(streamSize);
|
|
|
1589 |
return stream(makeArbitraryJumpsSpliterator(0L, streamSize, distance));
|
|
|
1590 |
}
|
|
|
1591 |
|
|
|
1592 |
/**
|
|
|
1593 |
* Alter the state of this pseudorandom number generator so as to
|
|
|
1594 |
* jump forward a very large, fixed distance (typically 2<sup>128</sup>
|
|
|
1595 |
* or more) within its state cycle. The distance used is that
|
|
|
1596 |
* returned by method {@code defaultLeapDistance()}.
|
|
|
1597 |
*/
|
|
|
1598 |
public void leap() {
|
|
|
1599 |
jump(defaultLeapDistance());
|
|
|
1600 |
}
|
|
|
1601 |
|
|
|
1602 |
// Stream methods for leaping
|
|
|
1603 |
|
|
|
1604 |
/**
|
|
|
1605 |
* Returns an effectively unlimited stream of new pseudorandom number generators, each of which
|
|
|
1606 |
* implements the {@link RandomGenerator} interface, produced by jumping copies of this
|
|
|
1607 |
* generator by different integer multiples of the default leap distance.
|
|
|
1608 |
*
|
|
|
1609 |
* @implNote This method is implemented to be equivalent to {@code leaps(Long.MAX_VALUE)}.
|
|
|
1610 |
*
|
|
|
1611 |
* @return a stream of objects that implement the {@link RandomGenerator} interface
|
|
|
1612 |
*/
|
|
|
1613 |
public Stream<JumpableGenerator> leaps() {
|
|
|
1614 |
return stream(makeLeapsSpliterator(0L, Long.MAX_VALUE, defaultLeapDistance()));
|
|
|
1615 |
}
|
|
|
1616 |
|
|
|
1617 |
/**
|
|
|
1618 |
* Returns a stream producing the given {@code streamSize} number of new pseudorandom number
|
|
|
1619 |
* generators, each of which implements the {@link RandomGenerator} interface, produced by
|
|
|
1620 |
* jumping copies of this generator by different integer multiples of the default leap
|
|
|
1621 |
* distance.
|
|
|
1622 |
*
|
|
|
1623 |
* @param streamSize the number of generators to generate
|
|
|
1624 |
*
|
|
|
1625 |
* @return a stream of objects that implement the {@link RandomGenerator} interface
|
|
|
1626 |
*
|
|
|
1627 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero
|
|
|
1628 |
*/
|
|
|
1629 |
public Stream<JumpableGenerator> leaps(long streamSize) {
|
|
|
1630 |
return stream(makeLeapsSpliterator(0L, streamSize, defaultLeapDistance()));
|
|
|
1631 |
}
|
|
|
1632 |
|
|
|
1633 |
|
|
|
1634 |
/**
|
|
|
1635 |
* Spliterator for int streams. We multiplex the four int versions into one class by treating a
|
|
|
1636 |
* bound less than origin as unbounded, and also by treating "infinite" as equivalent to
|
|
|
1637 |
* {@code Long.MAX_VALUE}. For splits, we choose to override the method {@code trySplit()} to
|
|
|
1638 |
* try to optimize execution speed: instead of dividing a range in half, it breaks off the
|
|
|
1639 |
* largest possible chunk whose size is a power of two such that the remaining chunk is not
|
|
|
1640 |
* empty. In this way, the necessary jump distances will tend to be powers of two. The long
|
|
|
1641 |
* and double versions of this class are identical except for types.
|
|
|
1642 |
*/
|
|
|
1643 |
static class RandomIntsSpliterator extends RandomSupport.RandomSpliterator implements Spliterator.OfInt {
|
|
|
1644 |
final ArbitrarilyJumpableGenerator generatingGenerator;
|
|
|
1645 |
final int origin;
|
|
|
1646 |
final int bound;
|
|
|
1647 |
|
|
|
1648 |
RandomIntsSpliterator(ArbitrarilyJumpableGenerator generatingGenerator, long index, long fence, int origin, int bound) {
|
|
|
1649 |
super(index, fence);
|
|
|
1650 |
this.origin = origin; this.bound = bound;
|
|
|
1651 |
this.generatingGenerator = generatingGenerator;
|
|
|
1652 |
}
|
|
|
1653 |
|
|
|
1654 |
public Spliterator.OfInt trySplit() {
|
|
|
1655 |
long i = index, delta = Long.highestOneBit((fence - i) - 1), m = i + delta;
|
|
|
1656 |
if (m <= i) return null;
|
|
|
1657 |
index = m;
|
|
|
1658 |
ArbitrarilyJumpableGenerator r = generatingGenerator;
|
|
|
1659 |
return new RandomIntsSpliterator(r.copyAndJump((double)delta), i, m, origin, bound);
|
|
|
1660 |
}
|
|
|
1661 |
|
|
|
1662 |
public boolean tryAdvance(IntConsumer consumer) {
|
|
|
1663 |
if (consumer == null) throw new NullPointerException();
|
|
|
1664 |
long i = index, f = fence;
|
|
|
1665 |
if (i < f) {
|
|
|
1666 |
consumer.accept(RandomSupport.boundedNextInt(generatingGenerator, origin, bound));
|
|
|
1667 |
index = i + 1;
|
|
|
1668 |
return true;
|
|
|
1669 |
}
|
|
|
1670 |
else return false;
|
|
|
1671 |
}
|
|
|
1672 |
|
|
|
1673 |
public void forEachRemaining(IntConsumer consumer) {
|
|
|
1674 |
if (consumer == null) throw new NullPointerException();
|
|
|
1675 |
long i = index, f = fence;
|
|
|
1676 |
if (i < f) {
|
|
|
1677 |
index = f;
|
|
|
1678 |
ArbitrarilyJumpableGenerator r = generatingGenerator;
|
|
|
1679 |
int o = origin, b = bound;
|
|
|
1680 |
do {
|
|
|
1681 |
consumer.accept(RandomSupport.boundedNextInt(r, o, b));
|
|
|
1682 |
} while (++i < f);
|
|
|
1683 |
}
|
|
|
1684 |
}
|
|
|
1685 |
}
|
|
|
1686 |
|
|
|
1687 |
/**
|
|
|
1688 |
* Spliterator for long streams.
|
|
|
1689 |
*/
|
|
|
1690 |
static class RandomLongsSpliterator extends RandomSupport.RandomSpliterator implements Spliterator.OfLong {
|
|
|
1691 |
final ArbitrarilyJumpableGenerator generatingGenerator;
|
|
|
1692 |
final long origin;
|
|
|
1693 |
final long bound;
|
|
|
1694 |
|
|
|
1695 |
RandomLongsSpliterator(ArbitrarilyJumpableGenerator generatingGenerator, long index, long fence, long origin, long bound) {
|
|
|
1696 |
super(index, fence);
|
|
|
1697 |
this.generatingGenerator = generatingGenerator;
|
|
|
1698 |
this.origin = origin; this.bound = bound;
|
|
|
1699 |
}
|
|
|
1700 |
|
|
|
1701 |
public Spliterator.OfLong trySplit() {
|
|
|
1702 |
long i = index, delta = Long.highestOneBit((fence - i) - 1), m = i + delta;
|
|
|
1703 |
if (m <= i) return null;
|
|
|
1704 |
index = m;
|
|
|
1705 |
ArbitrarilyJumpableGenerator r = generatingGenerator;
|
|
|
1706 |
return new RandomLongsSpliterator(r.copyAndJump((double)delta), i, m, origin, bound);
|
|
|
1707 |
}
|
|
|
1708 |
|
|
|
1709 |
public boolean tryAdvance(LongConsumer consumer) {
|
|
|
1710 |
if (consumer == null) throw new NullPointerException();
|
|
|
1711 |
long i = index, f = fence;
|
|
|
1712 |
if (i < f) {
|
|
|
1713 |
consumer.accept(RandomSupport.boundedNextLong(generatingGenerator, origin, bound));
|
|
|
1714 |
index = i + 1;
|
|
|
1715 |
return true;
|
|
|
1716 |
}
|
|
|
1717 |
else return false;
|
|
|
1718 |
}
|
|
|
1719 |
|
|
|
1720 |
public void forEachRemaining(LongConsumer consumer) {
|
|
|
1721 |
if (consumer == null) throw new NullPointerException();
|
|
|
1722 |
long i = index, f = fence;
|
|
|
1723 |
if (i < f) {
|
|
|
1724 |
index = f;
|
|
|
1725 |
ArbitrarilyJumpableGenerator r = generatingGenerator;
|
|
|
1726 |
long o = origin, b = bound;
|
|
|
1727 |
do {
|
|
|
1728 |
consumer.accept(RandomSupport.boundedNextLong(r, o, b));
|
|
|
1729 |
} while (++i < f);
|
|
|
1730 |
}
|
|
|
1731 |
}
|
|
|
1732 |
}
|
|
|
1733 |
|
|
|
1734 |
/**
|
|
|
1735 |
* Spliterator for double streams.
|
|
|
1736 |
*/
|
|
|
1737 |
static class RandomDoublesSpliterator extends RandomSupport.RandomSpliterator implements Spliterator.OfDouble {
|
|
|
1738 |
final ArbitrarilyJumpableGenerator generatingGenerator;
|
|
|
1739 |
final double origin;
|
|
|
1740 |
final double bound;
|
|
|
1741 |
|
|
|
1742 |
RandomDoublesSpliterator(ArbitrarilyJumpableGenerator generatingGenerator, long index, long fence, double origin, double bound) {
|
|
|
1743 |
super(index, fence);
|
|
|
1744 |
this.generatingGenerator = generatingGenerator;
|
|
|
1745 |
this.origin = origin; this.bound = bound;
|
|
|
1746 |
}
|
|
|
1747 |
|
|
|
1748 |
public Spliterator.OfDouble trySplit() {
|
|
|
1749 |
|
|
|
1750 |
long i = index, delta = Long.highestOneBit((fence - i) - 1), m = i + delta;
|
|
|
1751 |
if (m <= i) return null;
|
|
|
1752 |
index = m;
|
|
|
1753 |
ArbitrarilyJumpableGenerator r = generatingGenerator;
|
|
|
1754 |
return new RandomDoublesSpliterator(r.copyAndJump((double)delta), i, m, origin, bound);
|
|
|
1755 |
}
|
|
|
1756 |
|
|
|
1757 |
public boolean tryAdvance(DoubleConsumer consumer) {
|
|
|
1758 |
if (consumer == null) throw new NullPointerException();
|
|
|
1759 |
long i = index, f = fence;
|
|
|
1760 |
if (i < f) {
|
|
|
1761 |
consumer.accept(RandomSupport.boundedNextDouble(generatingGenerator, origin, bound));
|
|
|
1762 |
index = i + 1;
|
|
|
1763 |
return true;
|
|
|
1764 |
}
|
|
|
1765 |
else return false;
|
|
|
1766 |
}
|
|
|
1767 |
|
|
|
1768 |
public void forEachRemaining(DoubleConsumer consumer) {
|
|
|
1769 |
if (consumer == null) throw new NullPointerException();
|
|
|
1770 |
long i = index, f = fence;
|
|
|
1771 |
if (i < f) {
|
|
|
1772 |
index = f;
|
|
|
1773 |
ArbitrarilyJumpableGenerator r = generatingGenerator;
|
|
|
1774 |
double o = origin, b = bound;
|
|
|
1775 |
do {
|
|
|
1776 |
consumer.accept(RandomSupport.boundedNextDouble(r, o, b));
|
|
|
1777 |
} while (++i < f);
|
|
|
1778 |
}
|
|
|
1779 |
}
|
|
|
1780 |
}
|
|
|
1781 |
|
|
|
1782 |
// Spliterators for producing new generators by jumping or leaping. The
|
|
|
1783 |
// complete implementation of each of these spliterators is right here.
|
|
|
1784 |
// In the same manner as for the preceding spliterators, the method trySplit() is
|
|
|
1785 |
// coded to optimize execution speed: instead of dividing a range
|
|
|
1786 |
// in half, it breaks off the largest possible chunk whose
|
|
|
1787 |
// size is a power of two such that the remaining chunk is not
|
|
|
1788 |
// empty. In this way, the necessary jump distances will tend to be
|
|
|
1789 |
// powers of two.
|
|
|
1790 |
|
|
|
1791 |
/**
|
|
|
1792 |
* Spliterator for stream of generators of type RandomGenerator produced by jumps.
|
|
|
1793 |
*/
|
|
|
1794 |
static class RandomJumpsSpliterator extends RandomSupport.RandomSpliterator implements Spliterator<RandomGenerator> {
|
|
|
1795 |
ArbitrarilyJumpableGenerator generatingGenerator;
|
|
|
1796 |
final double distance;
|
|
|
1797 |
|
|
|
1798 |
RandomJumpsSpliterator(ArbitrarilyJumpableGenerator generatingGenerator, long index, long fence, double distance) {
|
|
|
1799 |
super(index, fence);
|
|
|
1800 |
this.generatingGenerator = generatingGenerator; this.distance = distance;
|
|
|
1801 |
}
|
|
|
1802 |
|
|
|
1803 |
public Spliterator<RandomGenerator> trySplit() {
|
|
|
1804 |
long i = index, delta = Long.highestOneBit((fence - i) - 1), m = i + delta;
|
|
|
1805 |
if (m <= i) return null;
|
|
|
1806 |
index = m;
|
|
|
1807 |
ArbitrarilyJumpableGenerator r = generatingGenerator;
|
|
|
1808 |
// Because delta is a power of two, (distance * (double)delta) can always be computed exactly.
|
|
|
1809 |
return new RandomJumpsSpliterator(r.copyAndJump(distance * (double)delta), i, m, distance);
|
|
|
1810 |
}
|
|
|
1811 |
|
|
|
1812 |
public boolean tryAdvance(Consumer<? super RandomGenerator> consumer) {
|
|
|
1813 |
if (consumer == null) throw new NullPointerException();
|
|
|
1814 |
long i = index, f = fence;
|
|
|
1815 |
if (i < f) {
|
|
|
1816 |
consumer.accept(generatingGenerator.copyAndJump(distance));
|
|
|
1817 |
index = i + 1;
|
|
|
1818 |
return true;
|
|
|
1819 |
}
|
|
|
1820 |
return false;
|
|
|
1821 |
}
|
|
|
1822 |
|
|
|
1823 |
public void forEachRemaining(Consumer<? super RandomGenerator> consumer) {
|
|
|
1824 |
if (consumer == null) throw new NullPointerException();
|
|
|
1825 |
long i = index, f = fence;
|
|
|
1826 |
if (i < f) {
|
|
|
1827 |
index = f;
|
|
|
1828 |
ArbitrarilyJumpableGenerator r = generatingGenerator;
|
|
|
1829 |
do {
|
|
|
1830 |
consumer.accept(r.copyAndJump(distance));
|
|
|
1831 |
} while (++i < f);
|
|
|
1832 |
}
|
|
|
1833 |
}
|
|
|
1834 |
}
|
|
|
1835 |
|
|
|
1836 |
/**
|
|
|
1837 |
* Spliterator for stream of generators of type RandomGenerator produced by leaps.
|
|
|
1838 |
*/
|
|
|
1839 |
static class RandomLeapsSpliterator extends RandomSupport.RandomSpliterator implements Spliterator<JumpableGenerator> {
|
|
|
1840 |
ArbitrarilyJumpableGenerator generatingGenerator;
|
|
|
1841 |
final double distance;
|
|
|
1842 |
|
|
|
1843 |
RandomLeapsSpliterator(ArbitrarilyJumpableGenerator generatingGenerator, long index, long fence, double distance) {
|
|
|
1844 |
super(index, fence);
|
|
|
1845 |
this.generatingGenerator = generatingGenerator; this.distance = distance;
|
|
|
1846 |
}
|
|
|
1847 |
|
|
|
1848 |
public Spliterator<JumpableGenerator> trySplit() {
|
|
|
1849 |
long i = index, delta = Long.highestOneBit((fence - i) - 1), m = i + delta;
|
|
|
1850 |
if (m <= i) return null;
|
|
|
1851 |
index = m;
|
|
|
1852 |
// Because delta is a power of two, (distance * (double)delta) can always be computed exactly.
|
|
|
1853 |
return new RandomLeapsSpliterator(generatingGenerator.copyAndJump(distance * (double)delta), i, m, distance);
|
|
|
1854 |
}
|
|
|
1855 |
|
|
|
1856 |
public boolean tryAdvance(Consumer<? super JumpableGenerator> consumer) {
|
|
|
1857 |
if (consumer == null) throw new NullPointerException();
|
|
|
1858 |
long i = index, f = fence;
|
|
|
1859 |
if (i < f) {
|
|
|
1860 |
consumer.accept(generatingGenerator.copyAndJump(distance));
|
|
|
1861 |
index = i + 1;
|
|
|
1862 |
return true;
|
|
|
1863 |
}
|
|
|
1864 |
return false;
|
|
|
1865 |
}
|
|
|
1866 |
|
|
|
1867 |
public void forEachRemaining(Consumer<? super JumpableGenerator> consumer) {
|
|
|
1868 |
if (consumer == null) throw new NullPointerException();
|
|
|
1869 |
long i = index, f = fence;
|
|
|
1870 |
if (i < f) {
|
|
|
1871 |
index = f;
|
|
|
1872 |
ArbitrarilyJumpableGenerator r = generatingGenerator;
|
|
|
1873 |
do {
|
|
|
1874 |
consumer.accept(r.copyAndJump(distance));
|
|
|
1875 |
} while (++i < f);
|
|
|
1876 |
}
|
|
|
1877 |
}
|
|
|
1878 |
}
|
|
|
1879 |
|
|
|
1880 |
/**
|
|
|
1881 |
* Spliterator for stream of generators of type RandomGenerator produced by arbitrary jumps.
|
|
|
1882 |
*/
|
|
|
1883 |
static class RandomArbitraryJumpsSpliterator extends RandomSupport.RandomSpliterator implements Spliterator<ArbitrarilyJumpableGenerator> {
|
|
|
1884 |
ArbitrarilyJumpableGenerator generatingGenerator;
|
|
|
1885 |
final double distance;
|
|
|
1886 |
|
|
|
1887 |
RandomArbitraryJumpsSpliterator(ArbitrarilyJumpableGenerator generatingGenerator, long index, long fence, double distance) {
|
|
|
1888 |
super(index, fence);
|
|
|
1889 |
this.generatingGenerator = generatingGenerator; this.distance = distance;
|
|
|
1890 |
}
|
|
|
1891 |
|
|
|
1892 |
public Spliterator<ArbitrarilyJumpableGenerator> trySplit() {
|
|
|
1893 |
long i = index, delta = Long.highestOneBit((fence - i) - 1), m = i + delta;
|
|
|
1894 |
if (m <= i) return null;
|
|
|
1895 |
index = m;
|
|
|
1896 |
// Because delta is a power of two, (distance * (double)delta) can always be computed exactly.
|
|
|
1897 |
return new RandomArbitraryJumpsSpliterator(generatingGenerator.copyAndJump(distance * (double)delta), i, m, distance);
|
|
|
1898 |
}
|
|
|
1899 |
|
|
|
1900 |
public boolean tryAdvance(Consumer<? super ArbitrarilyJumpableGenerator> consumer) {
|
|
|
1901 |
if (consumer == null) throw new NullPointerException();
|
|
|
1902 |
long i = index, f = fence;
|
|
|
1903 |
if (i < f) {
|
|
|
1904 |
consumer.accept(generatingGenerator.copyAndJump(distance));
|
|
|
1905 |
index = i + 1;
|
|
|
1906 |
return true;
|
|
|
1907 |
}
|
|
|
1908 |
return false;
|
|
|
1909 |
}
|
|
|
1910 |
|
|
|
1911 |
public void forEachRemaining(Consumer<? super ArbitrarilyJumpableGenerator> consumer) {
|
|
|
1912 |
if (consumer == null) throw new NullPointerException();
|
|
|
1913 |
long i = index, f = fence;
|
|
|
1914 |
if (i < f) {
|
|
|
1915 |
index = f;
|
|
|
1916 |
ArbitrarilyJumpableGenerator r = generatingGenerator;
|
|
|
1917 |
do {
|
|
|
1918 |
consumer.accept(r.copyAndJump(distance));
|
|
|
1919 |
} while (++i < f);
|
|
|
1920 |
}
|
|
|
1921 |
}
|
|
|
1922 |
}
|
|
|
1923 |
|
|
|
1924 |
}
|
|
|
1925 |
|
|
|
1926 |
/**
|
|
|
1927 |
* This class provides much of the implementation of the {@link SplittableGenerator} interface, to
|
|
|
1928 |
* minimize the effort required to implement this interface.
|
|
|
1929 |
* <p>
|
|
|
1930 |
* To implement a pseudorandom number generator, the programmer needs only to extend this class and
|
|
|
1931 |
* provide implementations for the methods {@code nextInt()}, {@code nextLong()}, {@code period()},
|
|
|
1932 |
* and {@code split(SplittableGenerator)}.
|
|
|
1933 |
* <p>
|
|
|
1934 |
* (If the pseudorandom number generator also has the ability to jump an arbitrary
|
|
|
1935 |
* specified distance, then the programmer may wish to consider instead extending the
|
|
|
1936 |
* class {@link AbstractArbitrarilyJumpableGenerator}. See also the class
|
|
|
1937 |
* {@link AbstractSplittableWithBrineGenerator}.)
|
|
|
1938 |
* <p>
|
|
|
1939 |
* The programmer should generally provide at least three constructors: one that takes no arguments,
|
|
|
1940 |
* one that accepts a {@code long} seed value, and one that accepts an array of seed {@code byte}
|
|
|
1941 |
* values. This class provides a public {@code initialSeed()} method that may be useful in
|
|
|
1942 |
* initializing some static state from which to derive defaults seeds for use by the no-argument
|
|
|
1943 |
* constructor.
|
|
|
1944 |
* <p>
|
|
|
1945 |
* For the stream methods (such as {@code ints()} and {@code splits()}), this class provides
|
|
|
1946 |
* {@link Spliterator}-based implementations that allow parallel execution when appropriate.
|
|
|
1947 |
* <p>
|
|
|
1948 |
* The documentation for each non-abstract method in this class describes its implementation in
|
|
|
1949 |
* detail. Each of these methods may be overridden if the pseudorandom number generator being
|
|
|
1950 |
* implemented admits a more efficient implementation.
|
|
|
1951 |
*
|
|
|
1952 |
* @since 14
|
|
|
1953 |
*/
|
|
|
1954 |
public abstract static class AbstractSplittableGenerator extends AbstractSpliteratorGenerator implements SplittableGenerator {
|
|
|
1955 |
|
|
|
1956 |
/*
|
|
|
1957 |
* Implementation Overview.
|
|
|
1958 |
*
|
|
|
1959 |
* This class provides most of the "user API" methods needed to
|
|
|
1960 |
* satisfy the interface SplittableGenerator. Most of these methods
|
|
|
1961 |
* are in turn inherited from AbstractGenerator and the non-public class
|
|
|
1962 |
* AbstractSpliteratorGenerator; this class provides two versions of the
|
|
|
1963 |
* splits method and defines the spliterators necessary to support
|
|
|
1964 |
* them.
|
|
|
1965 |
*
|
|
|
1966 |
* File organization: First the non-public methods needed by the class
|
|
|
1967 |
* AbstractSpliteratorGenerator, then the main public methods, followed by some
|
|
|
1968 |
* custom spliterator classes.
|
|
|
1969 |
*/
|
|
|
1970 |
|
|
|
1971 |
public Spliterator.OfInt makeIntsSpliterator(long index, long fence, int origin, int bound) {
|
|
|
1972 |
return new RandomIntsSpliterator(this, index, fence, origin, bound);
|
|
|
1973 |
}
|
|
|
1974 |
|
|
|
1975 |
public Spliterator.OfLong makeLongsSpliterator(long index, long fence, long origin, long bound) {
|
|
|
1976 |
return new RandomLongsSpliterator(this, index, fence, origin, bound);
|
|
|
1977 |
}
|
|
|
1978 |
|
|
|
1979 |
public Spliterator.OfDouble makeDoublesSpliterator(long index, long fence, double origin, double bound) {
|
|
|
1980 |
return new RandomDoublesSpliterator(this, index, fence, origin, bound);
|
|
|
1981 |
}
|
|
|
1982 |
|
|
|
1983 |
Spliterator<SplittableGenerator> makeSplitsSpliterator(long index, long fence, SplittableGenerator source) {
|
|
|
1984 |
return new RandomSplitsSpliterator(source, index, fence, this);
|
|
|
1985 |
}
|
|
|
1986 |
|
|
|
1987 |
/* ---------------- public methods ---------------- */
|
|
|
1988 |
|
|
|
1989 |
/**
|
|
|
1990 |
* Implements the @code{split()} method as {@code this.split(this)}.
|
|
|
1991 |
*
|
|
|
1992 |
* @return the new {@link SplittableGenerator} instance
|
|
|
1993 |
*/
|
|
|
1994 |
public SplittableGenerator split() {
|
|
|
1995 |
return this.split(this);
|
|
|
1996 |
}
|
|
|
1997 |
|
|
|
1998 |
// Stream methods for splittings
|
|
|
1999 |
|
|
|
2000 |
/**
|
|
|
2001 |
* Returns an effectively unlimited stream of new pseudorandom number generators, each of which
|
|
|
2002 |
* implements the {@link SplittableGenerator} interface.
|
|
|
2003 |
* <p>
|
|
|
2004 |
* This pseudorandom number generator provides the entropy used to seed the new ones.
|
|
|
2005 |
*
|
|
|
2006 |
* @return a stream of {@link SplittableGenerator} objects
|
|
|
2007 |
*
|
|
|
2008 |
* @implNote This method is implemented to be equivalent to {@code splits(Long.MAX_VALUE)}.
|
|
|
2009 |
*/
|
|
|
2010 |
public Stream<SplittableGenerator> splits() {
|
|
|
2011 |
return this.splits(Long.MAX_VALUE, this);
|
|
|
2012 |
}
|
|
|
2013 |
|
|
|
2014 |
/**
|
|
|
2015 |
* Returns a stream producing the given {@code streamSize} number of new pseudorandom number
|
|
|
2016 |
* generators, each of which implements the {@link SplittableGenerator} interface.
|
|
|
2017 |
* <p>
|
|
|
2018 |
* This pseudorandom number generator provides the entropy used to seed the new ones.
|
|
|
2019 |
*
|
|
|
2020 |
* @param streamSize the number of values to generate
|
|
|
2021 |
*
|
|
|
2022 |
* @return a stream of {@link SplittableGenerator} objects
|
|
|
2023 |
*
|
|
|
2024 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero
|
|
|
2025 |
*/
|
|
|
2026 |
public Stream<SplittableGenerator> splits(long streamSize) {
|
|
|
2027 |
return this.splits(streamSize, this);
|
|
|
2028 |
}
|
|
|
2029 |
|
|
|
2030 |
/**
|
|
|
2031 |
* Returns an effectively unlimited stream of new pseudorandom number generators, each of which
|
|
|
2032 |
* implements the {@link SplittableGenerator} interface.
|
|
|
2033 |
*
|
|
|
2034 |
* @param source a {@link SplittableGenerator} instance to be used instead of this one as a source of
|
|
|
2035 |
* pseudorandom bits used to initialize the state of the new ones.
|
|
|
2036 |
*
|
|
|
2037 |
* @return a stream of {@link SplittableGenerator} objects
|
|
|
2038 |
*
|
|
|
2039 |
* @implNote This method is implemented to be equivalent to {@code splits(Long.MAX_VALUE)}.
|
|
|
2040 |
*/
|
|
|
2041 |
public Stream<SplittableGenerator> splits(SplittableGenerator source) {
|
|
|
2042 |
return this.splits(Long.MAX_VALUE, source);
|
|
|
2043 |
}
|
|
|
2044 |
|
|
|
2045 |
/**
|
|
|
2046 |
* Returns a stream producing the given {@code streamSize} number of new pseudorandom number
|
|
|
2047 |
* generators, each of which implements the {@link SplittableGenerator} interface.
|
|
|
2048 |
*
|
|
|
2049 |
* @param streamSize the number of values to generate
|
|
|
2050 |
* @param source a {@link SplittableGenerator} instance to be used instead of this one as a source
|
|
|
2051 |
* of pseudorandom bits used to initialize the state of the new ones.
|
|
|
2052 |
*
|
|
|
2053 |
* @return a stream of {@link SplittableGenerator} objects
|
|
|
2054 |
*
|
|
|
2055 |
* @throws IllegalArgumentException if {@code streamSize} is less than zero
|
|
|
2056 |
*/
|
|
|
2057 |
public Stream<SplittableGenerator> splits(long streamSize, SplittableGenerator source) {
|
|
|
2058 |
RandomSupport.checkStreamSize(streamSize);
|
|
|
2059 |
return StreamSupport.stream(makeSplitsSpliterator(0L, streamSize, source), false);
|
|
|
2060 |
}
|
|
|
2061 |
|
|
|
2062 |
/**
|
|
|
2063 |
* Spliterator for int streams. We multiplex the four int versions into one class by treating a
|
|
|
2064 |
* bound less than origin as unbounded, and also by treating "infinite" as equivalent to
|
|
|
2065 |
* {@code Long.MAX_VALUE}. For splits, it uses the standard divide-by-two approach. The long and
|
|
|
2066 |
* double versions of this class are identical except for types.
|
|
|
2067 |
*/
|
|
|
2068 |
static class RandomIntsSpliterator extends RandomSupport.RandomSpliterator implements Spliterator.OfInt {
|
|
|
2069 |
final SplittableGenerator generatingGenerator;
|
|
|
2070 |
final int origin;
|
|
|
2071 |
final int bound;
|
|
|
2072 |
|
|
|
2073 |
RandomIntsSpliterator(SplittableGenerator generatingGenerator, long index, long fence, int origin, int bound) {
|
|
|
2074 |
super(index, fence);
|
|
|
2075 |
this.generatingGenerator = generatingGenerator;
|
|
|
2076 |
this.origin = origin; this.bound = bound;
|
|
|
2077 |
}
|
|
|
2078 |
|
|
|
2079 |
public Spliterator.OfInt trySplit() {
|
|
|
2080 |
long i = index, m = (i + fence) >>> 1;
|
|
|
2081 |
if (m <= i) return null;
|
|
|
2082 |
index = m;
|
|
|
2083 |
return new RandomIntsSpliterator(generatingGenerator.split(), i, m, origin, bound);
|
|
|
2084 |
}
|
|
|
2085 |
|
|
|
2086 |
public boolean tryAdvance(IntConsumer consumer) {
|
|
|
2087 |
if (consumer == null) throw new NullPointerException();
|
|
|
2088 |
long i = index, f = fence;
|
|
|
2089 |
if (i < f) {
|
|
|
2090 |
consumer.accept(RandomSupport.boundedNextInt(generatingGenerator, origin, bound));
|
|
|
2091 |
index = i + 1;
|
|
|
2092 |
return true;
|
|
|
2093 |
}
|
|
|
2094 |
else return false;
|
|
|
2095 |
}
|
|
|
2096 |
|
|
|
2097 |
public void forEachRemaining(IntConsumer consumer) {
|
|
|
2098 |
if (consumer == null) throw new NullPointerException();
|
|
|
2099 |
long i = index, f = fence;
|
|
|
2100 |
if (i < f) {
|
|
|
2101 |
index = f;
|
|
|
2102 |
RandomGenerator r = generatingGenerator;
|
|
|
2103 |
int o = origin, b = bound;
|
|
|
2104 |
do {
|
|
|
2105 |
consumer.accept(RandomSupport.boundedNextInt(r, o, b));
|
|
|
2106 |
} while (++i < f);
|
|
|
2107 |
}
|
|
|
2108 |
}
|
|
|
2109 |
}
|
|
|
2110 |
|
|
|
2111 |
/**
|
|
|
2112 |
* Spliterator for long streams.
|
|
|
2113 |
*/
|
|
|
2114 |
static class RandomLongsSpliterator extends RandomSupport.RandomSpliterator implements Spliterator.OfLong {
|
|
|
2115 |
final SplittableGenerator generatingGenerator;
|
|
|
2116 |
final long origin;
|
|
|
2117 |
final long bound;
|
|
|
2118 |
|
|
|
2119 |
RandomLongsSpliterator(SplittableGenerator generatingGenerator, long index, long fence, long origin, long bound) {
|
|
|
2120 |
super(index, fence);
|
|
|
2121 |
this.generatingGenerator = generatingGenerator;
|
|
|
2122 |
this.origin = origin; this.bound = bound;
|
|
|
2123 |
}
|
|
|
2124 |
|
|
|
2125 |
public Spliterator.OfLong trySplit() {
|
|
|
2126 |
long i = index, m = (i + fence) >>> 1;
|
|
|
2127 |
if (m <= i) return null;
|
|
|
2128 |
index = m;
|
|
|
2129 |
return new RandomLongsSpliterator(generatingGenerator.split(), i, m, origin, bound);
|
|
|
2130 |
}
|
|
|
2131 |
|
|
|
2132 |
public boolean tryAdvance(LongConsumer consumer) {
|
|
|
2133 |
if (consumer == null) throw new NullPointerException();
|
|
|
2134 |
long i = index, f = fence;
|
|
|
2135 |
if (i < f) {
|
|
|
2136 |
consumer.accept(RandomSupport.boundedNextLong(generatingGenerator, origin, bound));
|
|
|
2137 |
index = i + 1;
|
|
|
2138 |
return true;
|
|
|
2139 |
}
|
|
|
2140 |
else return false;
|
|
|
2141 |
}
|
|
|
2142 |
|
|
|
2143 |
public void forEachRemaining(LongConsumer consumer) {
|
|
|
2144 |
if (consumer == null) throw new NullPointerException();
|
|
|
2145 |
long i = index, f = fence;
|
|
|
2146 |
if (i < f) {
|
|
|
2147 |
index = f;
|
|
|
2148 |
RandomGenerator r = generatingGenerator;
|
|
|
2149 |
long o = origin, b = bound;
|
|
|
2150 |
do {
|
|
|
2151 |
consumer.accept(RandomSupport.boundedNextLong(r, o, b));
|
|
|
2152 |
} while (++i < f);
|
|
|
2153 |
}
|
|
|
2154 |
}
|
|
|
2155 |
}
|
|
|
2156 |
|
|
|
2157 |
/**
|
|
|
2158 |
* Spliterator for double streams.
|
|
|
2159 |
*/
|
|
|
2160 |
static class RandomDoublesSpliterator extends RandomSupport.RandomSpliterator implements Spliterator.OfDouble {
|
|
|
2161 |
final SplittableGenerator generatingGenerator;
|
|
|
2162 |
final double origin;
|
|
|
2163 |
final double bound;
|
|
|
2164 |
|
|
|
2165 |
RandomDoublesSpliterator(SplittableGenerator generatingGenerator, long index, long fence, double origin, double bound) {
|
|
|
2166 |
super(index, fence);
|
|
|
2167 |
this.generatingGenerator = generatingGenerator;
|
|
|
2168 |
this.origin = origin; this.bound = bound;
|
|
|
2169 |
}
|
|
|
2170 |
|
|
|
2171 |
public Spliterator.OfDouble trySplit() {
|
|
|
2172 |
long i = index, m = (i + fence) >>> 1;
|
|
|
2173 |
if (m <= i) return null;
|
|
|
2174 |
index = m;
|
|
|
2175 |
return new RandomDoublesSpliterator(generatingGenerator.split(), i, m, origin, bound);
|
|
|
2176 |
}
|
|
|
2177 |
|
|
|
2178 |
public boolean tryAdvance(DoubleConsumer consumer) {
|
|
|
2179 |
if (consumer == null) throw new NullPointerException();
|
|
|
2180 |
long i = index, f = fence;
|
|
|
2181 |
if (i < f) {
|
|
|
2182 |
consumer.accept(RandomSupport.boundedNextDouble(generatingGenerator, origin, bound));
|
|
|
2183 |
index = i + 1;
|
|
|
2184 |
return true;
|
|
|
2185 |
}
|
|
|
2186 |
else return false;
|
|
|
2187 |
}
|
|
|
2188 |
|
|
|
2189 |
public void forEachRemaining(DoubleConsumer consumer) {
|
|
|
2190 |
if (consumer == null) throw new NullPointerException();
|
|
|
2191 |
long i = index, f = fence;
|
|
|
2192 |
if (i < f) {
|
|
|
2193 |
index = f;
|
|
|
2194 |
RandomGenerator r = generatingGenerator;
|
|
|
2195 |
double o = origin, b = bound;
|
|
|
2196 |
do {
|
|
|
2197 |
consumer.accept(RandomSupport.boundedNextDouble(r, o, b));
|
|
|
2198 |
} while (++i < f);
|
|
|
2199 |
}
|
|
|
2200 |
}
|
|
|
2201 |
}
|
|
|
2202 |
|
|
|
2203 |
/**
|
|
|
2204 |
* Spliterator for stream of generators of type SplittableGenerator. We multiplex the two
|
|
|
2205 |
* versions into one class by treating "infinite" as equivalent to Long.MAX_VALUE.
|
|
|
2206 |
* For splits, it uses the standard divide-by-two approach.
|
|
|
2207 |
*/
|
|
|
2208 |
static class RandomSplitsSpliterator extends RandomSpliterator implements Spliterator<SplittableGenerator> {
|
|
|
2209 |
final SplittableGenerator generatingGenerator;
|
|
|
2210 |
final SplittableGenerator constructingGenerator;
|
|
|
2211 |
|
|
|
2212 |
RandomSplitsSpliterator(SplittableGenerator generatingGenerator,
|
|
|
2213 |
long index, long fence,
|
|
|
2214 |
SplittableGenerator constructingGenerator) {
|
|
|
2215 |
super(index, fence);
|
|
|
2216 |
this.generatingGenerator = generatingGenerator;
|
|
|
2217 |
this.constructingGenerator = constructingGenerator;
|
|
|
2218 |
}
|
|
|
2219 |
|
|
|
2220 |
public Spliterator<SplittableGenerator> trySplit() {
|
|
|
2221 |
long i = index, m = (i + fence) >>> 1;
|
|
|
2222 |
if (m <= i) return null;
|
|
|
2223 |
index = m;
|
|
|
2224 |
return new RandomSplitsSpliterator(generatingGenerator.split(), i, m, constructingGenerator);
|
|
|
2225 |
}
|
|
|
2226 |
|
|
|
2227 |
public boolean tryAdvance(Consumer<? super SplittableGenerator> consumer) {
|
|
|
2228 |
if (consumer == null) throw new NullPointerException();
|
|
|
2229 |
long i = index, f = fence;
|
|
|
2230 |
if (i < f) {
|
|
|
2231 |
consumer.accept(constructingGenerator.split(generatingGenerator));
|
|
|
2232 |
index = i + 1;
|
|
|
2233 |
return true;
|
|
|
2234 |
}
|
|
|
2235 |
else return false;
|
|
|
2236 |
}
|
|
|
2237 |
|
|
|
2238 |
public void forEachRemaining(Consumer<? super SplittableGenerator> consumer) {
|
|
|
2239 |
if (consumer == null) throw new NullPointerException();
|
|
|
2240 |
long i = index, f = fence;
|
|
|
2241 |
if (i < f) {
|
|
|
2242 |
index = f;
|
|
|
2243 |
SplittableGenerator c = constructingGenerator;
|
|
|
2244 |
SplittableGenerator r = generatingGenerator;
|
|
|
2245 |
do {
|
|
|
2246 |
consumer.accept(c.split(r));
|
|
|
2247 |
} while (++i < f);
|
|
|
2248 |
}
|
|
|
2249 |
}
|
|
|
2250 |
}
|
|
|
2251 |
|
|
|
2252 |
}
|
|
|
2253 |
|
|
|
2254 |
/**
|
|
|
2255 |
* This class provides much of the implementation of the {@link SplittableGenerator} interface, to
|
|
|
2256 |
* minimize the effort required to implement this interface. It is similar to the class
|
|
|
2257 |
* {@link AbstractSplittableGenerator} but makes use of the brine technique for ensuring that
|
|
|
2258 |
* distinct generators created by a single call to a {@code splits} method have distinct state cycles.
|
|
|
2259 |
* <p>
|
|
|
2260 |
* To implement a pseudorandom number generator, the programmer needs only to extend this class and
|
|
|
2261 |
* provide implementations for the methods {@code nextInt()}, {@code nextLong()}, {@code period()},
|
|
|
2262 |
* and {@code split(SplittableGenerator, long)}.
|
|
|
2263 |
* <p>
|
|
|
2264 |
* The programmer should generally provide at least three constructors: one that takes no arguments,
|
|
|
2265 |
* one that accepts a {@code long} seed value, and one that accepts an array of seed {@code byte}
|
|
|
2266 |
* values. This class provides a public {@code initialSeed()} method that may be useful in
|
|
|
2267 |
* initializing some static state from which to derive defaults seeds for use by the no-argument
|
|
|
2268 |
* constructor.
|
|
|
2269 |
* <p>
|
|
|
2270 |
* For the stream methods (such as {@code ints()} and {@code splits()}), this class provides
|
|
|
2271 |
* {@link Spliterator}-based implementations that allow parallel execution when appropriate.
|
|
|
2272 |
* <p>
|
|
|
2273 |
* The documentation for each non-abstract method in this class describes its implementation in
|
|
|
2274 |
* detail. Each of these methods may be overridden if the pseudorandom number generator being
|
|
|
2275 |
* implemented admits a more efficient implementation.
|
|
|
2276 |
*
|
|
|
2277 |
* @since 14
|
|
|
2278 |
*/
|
|
|
2279 |
public abstract static class AbstractSplittableWithBrineGenerator
|
|
|
2280 |
extends AbstractSplittableGenerator {
|
|
|
2281 |
|
|
|
2282 |
/*
|
|
|
2283 |
* Implementation Overview.
|
|
|
2284 |
*
|
|
|
2285 |
* This class provides most of the "user API" methods needed to
|
|
|
2286 |
* satisfy the interface SplittableGenerator. Most of these methods
|
|
|
2287 |
* are in turn inherited from AbstractSplittableGenerator and the non-public class
|
|
|
2288 |
* AbstractSpliteratorGenerator; this class provides four versions of the
|
|
|
2289 |
* splits method and defines the spliterators necessary to support
|
|
|
2290 |
* them.
|
|
|
2291 |
*
|
|
|
2292 |
* File organization: First the non-public methods needed by the class
|
|
|
2293 |
* AbstractSplittableWithBrineGenerator, then the main public methods,
|
|
|
2294 |
* followed by some custom spliterator classes needed for stream methods.
|
|
|
2295 |
*/
|
|
|
2296 |
|
|
|
2297 |
// The salt consists groups of bits each SALT_SHIFT in size, starting from
|
|
|
2298 |
// the left-hand (high-order) end of the word. We can regard them as
|
|
|
2299 |
// digits base (1 << SALT_SHIFT). If SALT_SHIFT does not divide 64
|
|
|
2300 |
// evenly, then any leftover bits at the low end of the word are zero.
|
|
|
2301 |
// The lowest digit of the salt is set to the largest possible digit
|
|
|
2302 |
// (all 1-bits, or ((1 << SALT_SHIFT) - 1)); all other digits are set
|
|
|
2303 |
// to a randomly chosen value less than that largest possible digit.
|
|
|
2304 |
// The salt may be shifted left by SALT_SHIFT any number of times.
|
|
|
2305 |
// If any salt remains in the word, its right-hand end can be identified
|
|
|
2306 |
// by searching from left to right for an occurrence of a digit that is
|
|
|
2307 |
// all 1-bits (not that we ever do that; this is simply a proof that one
|
|
|
2308 |
// can identify the boundary between the salt and the index if any salt
|
|
|
2309 |
// remains in the word). The idea is that before computing the bitwise OR
|
|
|
2310 |
// of an index and the salt, one can first check to see whether the
|
|
|
2311 |
// bitwise AND is nonzero; if so, one can shift the salt left by
|
|
|
2312 |
// SALT_SHIFT and try again. In this way, when the bitwise OR is
|
|
|
2313 |
// computed, if the salt is nonzero then its rightmost 1-bit is to the
|
|
|
2314 |
// left of the leftmost 1-bit of the index.
|
|
|
2315 |
|
|
|
2316 |
// We need 2 <= SALT_SHIFT <= 63 (3 through 8 are good values; 4 is probably best)
|
|
|
2317 |
static final int SALT_SHIFT = 4;
|
|
|
2318 |
|
|
|
2319 |
// Methods required by class AbstractSpliteratorGenerator (override)
|
|
|
2320 |
Spliterator<SplittableGenerator> makeSplitsSpliterator(long index, long fence, SplittableGenerator source) {
|
|
|
2321 |
// This little algorithm to generate a new salt value is carefully
|
|
|
2322 |
// designed to work even if SALT_SHIFT does not evenly divide 64
|
|
|
2323 |
// (the number of bits in a long value).
|
|
|
2324 |
long bits = nextLong();
|
|
|
2325 |
long multiplier = (1 << SALT_SHIFT) - 1;
|
|
|
2326 |
long salt = multiplier << (64 - SALT_SHIFT);
|
|
|
2327 |
while ((salt & multiplier) != 0) {
|
|
|
2328 |
long digit = Math.multiplyHigh(bits, multiplier);
|
|
|
2329 |
salt = (salt >>> SALT_SHIFT) | (digit << (64 - SALT_SHIFT));
|
|
|
2330 |
bits *= multiplier;
|
|
|
2331 |
}
|
|
|
2332 |
// This is the point at which newly generated salt gets injected into
|
|
|
2333 |
// the root of a newly created brine-generating splits-spliterator.
|
|
|
2334 |
return new RandomSplitsSpliteratorWithSalt(source, index, fence, this, salt);
|
|
|
2335 |
}
|
|
|
2336 |
|
|
|
2337 |
/* ---------------- public methods ---------------- */
|
|
|
2338 |
|
|
|
2339 |
// Stream methods for splitting
|
|
|
2340 |
|
|
|
2341 |
/**
|
|
|
2342 |
* Constructs and returns a new instance of {@code AbstractSplittableWithBrineGenerator}
|
|
|
2343 |
* that shares no mutable state with this instance. However, with very high
|
|
|
2344 |
* probability, the set of values collectively generated by the two objects
|
|
|
2345 |
* should have the same statistical properties as if the same quantity of
|
|
|
2346 |
* values were generated by a single thread using a single may be
|
|
|
2347 |
* {@code AbstractSplittableWithBrineGenerator} object. Either or both of the two objects
|
|
|
2348 |
* further split using the {@code split()} method, and the same expected
|
|
|
2349 |
* statistical properties apply to the entire set of generators constructed
|
|
|
2350 |
* by such recursive splitting.
|
|
|
2351 |
*
|
|
|
2352 |
* @param brine a long value, of which the low 63 bits provide a unique id
|
|
|
2353 |
* among calls to this method for constructing a single series of Generator objects.
|
|
|
2354 |
*
|
|
|
2355 |
* @return the new {@code AbstractSplittableWithBrineGenerator} instance
|
|
|
2356 |
*/
|
|
|
2357 |
public SplittableGenerator split(long brine) {
|
|
|
2358 |
return this.split(this, brine);
|
|
|
2359 |
}
|
|
|
2360 |
|
|
|
2361 |
/**
|
|
|
2362 |
* Constructs and returns a new instance of {@code L64X128MixRandom}
|
|
|
2363 |
* that shares no mutable state with this instance.
|
|
|
2364 |
* However, with very high probability, the set of values collectively
|
|
|
2365 |
* generated by the two objects has the same statistical properties as if
|
|
|
2366 |
* same the quantity of values were generated by a single thread using
|
|
|
2367 |
* a single {@code L64X128MixRandom} object. Either or both of the two
|
|
|
2368 |
* objects may be further split using the {@code split} method,
|
|
|
2369 |
* and the same expected statistical properties apply to the
|
|
|
2370 |
* entire set of generators constructed by such recursive splitting.
|
|
|
2371 |
*
|
|
|
2372 |
* @param source a {@code SplittableGenerator} instance to be used instead
|
|
|
2373 |
* of this one as a source of pseudorandom bits used to
|
|
|
2374 |
* initialize the state of the new ones.
|
|
|
2375 |
* @return a new instance of {@code L64X128MixRandom}
|
|
|
2376 |
*/
|
|
|
2377 |
public SplittableGenerator split(SplittableGenerator source) {
|
|
|
2378 |
// It's a one-off: supply randomly chosen brine
|
|
|
2379 |
return this.split(source, source.nextLong());
|
|
|
2380 |
}
|
|
|
2381 |
|
|
|
2382 |
/**
|
|
|
2383 |
* Constructs and returns a new instance of {@code AbstractSplittableWithBrineGenerator}
|
|
|
2384 |
* that shares no mutable state with this instance. However, with very high
|
|
|
2385 |
* probability, the set of values collectively generated by the two objects
|
|
|
2386 |
* should have the same statistical properties as if the same quantity of
|
|
|
2387 |
* values were generated by a single thread using a single may be
|
|
|
2388 |
* {@code AbstractSplittableWithBrineGenerator} object. Either or both of the two objects
|
|
|
2389 |
* further split using the {@code split()} method, and the same expected
|
|
|
2390 |
* statistical properties apply to the entire set of generators constructed
|
|
|
2391 |
* by such recursive splitting.
|
|
|
2392 |
*
|
|
|
2393 |
* @param source a {@code SplittableGenerator} instance to be used instead
|
|
|
2394 |
* of this one as a source of pseudorandom bits used to
|
|
|
2395 |
* initialize the state of the new ones.
|
|
|
2396 |
* @param brine a long value, of which the low 63 bits provide a unique id
|
|
|
2397 |
* among calls to this method for constructing a single series of
|
|
|
2398 |
* {@code RandomGenerator} objects.
|
|
|
2399 |
*
|
|
|
2400 |
* @return the new {@code AbstractSplittableWithBrineGenerator} instance
|
|
|
2401 |
*/
|
|
|
2402 |
public abstract SplittableGenerator split(SplittableGenerator source, long brine);
|
|
|
2403 |
|
|
|
2404 |
|
|
|
2405 |
/* ---------------- spliterator ---------------- */
|
|
|
2406 |
/**
|
|
|
2407 |
* Alternate spliterator for stream of generators of type SplittableGenerator. We multiplex
|
|
|
2408 |
* the two versions into one class by treating "infinite" as equivalent to Long.MAX_VALUE.
|
|
|
2409 |
* For splits, it uses the standard divide-by-two approach.
|
|
|
2410 |
*
|
|
|
2411 |
* This differs from {@code SplittableGenerator.RandomSplitsSpliterator} in that it provides
|
|
|
2412 |
* a brine argument (a mixture of salt and an index) when calling the {@code split} method.
|
|
|
2413 |
*/
|
|
|
2414 |
static class RandomSplitsSpliteratorWithSalt
|
|
|
2415 |
extends RandomSpliterator implements Spliterator<SplittableGenerator> {
|
|
|
2416 |
|
|
|
2417 |
final SplittableGenerator generatingGenerator;
|
|
|
2418 |
final AbstractSplittableWithBrineGenerator constructingGenerator;
|
|
|
2419 |
long salt;
|
|
|
2420 |
|
|
|
2421 |
// Important invariant: 0 <= index <= fence
|
|
|
2422 |
|
|
|
2423 |
// Important invariant: if salt and index are both nonzero,
|
|
|
2424 |
// the rightmost 1-bit of salt is to the left of the leftmost 1-bit of index.
|
|
|
2425 |
// If necessary, the salt can be leftshifted by SALT_SHIFT as many times as
|
|
|
2426 |
// necessary to maintain the invariant.
|
|
|
2427 |
|
|
|
2428 |
RandomSplitsSpliteratorWithSalt(SplittableGenerator generatingGenerator, long index, long fence,
|
|
|
2429 |
AbstractSplittableWithBrineGenerator constructingGenerator, long salt) {
|
|
|
2430 |
super(index, fence);
|
|
|
2431 |
this.generatingGenerator = generatingGenerator;
|
|
|
2432 |
this.constructingGenerator = constructingGenerator;
|
|
|
2433 |
while ((salt != 0) && (Long.compareUnsigned(salt & -salt, index) <= 0)) {
|
|
|
2434 |
salt = salt << SALT_SHIFT;
|
|
|
2435 |
}
|
|
|
2436 |
this.salt = salt;
|
|
|
2437 |
}
|
|
|
2438 |
|
|
|
2439 |
public Spliterator<SplittableGenerator> trySplit() {
|
|
|
2440 |
long i = index, m = (i + fence) >>> 1;
|
|
|
2441 |
if (m <= i) return null;
|
|
|
2442 |
RandomSplitsSpliteratorWithSalt result =
|
|
|
2443 |
new RandomSplitsSpliteratorWithSalt(generatingGenerator.split(), i, m, constructingGenerator, salt);
|
|
|
2444 |
index = m;
|
|
|
2445 |
while ((salt != 0) && (Long.compareUnsigned(salt & -salt, index) <= 0)) {
|
|
|
2446 |
salt = salt << SALT_SHIFT;
|
|
|
2447 |
}
|
|
|
2448 |
return result;
|
|
|
2449 |
}
|
|
|
2450 |
|
|
|
2451 |
public boolean tryAdvance(Consumer<? super SplittableGenerator> consumer) {
|
|
|
2452 |
if (consumer == null) throw new NullPointerException();
|
|
|
2453 |
long i = index, f = fence;
|
|
|
2454 |
if (i < f) {
|
|
|
2455 |
consumer.accept(constructingGenerator.split(generatingGenerator, salt | i));
|
|
|
2456 |
++i;
|
|
|
2457 |
index = i;
|
|
|
2458 |
if ((i & salt) != 0) salt <<= SALT_SHIFT;
|
|
|
2459 |
return true;
|
|
|
2460 |
}
|
|
|
2461 |
return false;
|
|
|
2462 |
}
|
|
|
2463 |
|
|
|
2464 |
public void forEachRemaining(Consumer<? super SplittableGenerator> consumer) {
|
|
|
2465 |
if (consumer == null) throw new NullPointerException();
|
|
|
2466 |
long i = index, f = fence;
|
|
|
2467 |
if (i < f) {
|
|
|
2468 |
index = f;
|
|
|
2469 |
AbstractSplittableWithBrineGenerator c = constructingGenerator;
|
|
|
2470 |
SplittableGenerator r = generatingGenerator;
|
|
|
2471 |
do {
|
|
|
2472 |
consumer.accept(c.split(r, salt | i));
|
|
|
2473 |
++i;
|
|
|
2474 |
if ((i & salt) != 0) salt <<= SALT_SHIFT;
|
|
|
2475 |
} while (i < f);
|
|
|
2476 |
}
|
|
|
2477 |
}
|
|
|
2478 |
}
|
|
|
2479 |
|
|
|
2480 |
}
|
|
|
2481 |
|
|
|
2482 |
}
|