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/* |
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* Copyright (c) 2013, 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; |
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import java.util.concurrent.atomic.AtomicLong; |
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import java.util.Spliterator; |
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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.function.DoubleConsumer; |
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import java.util.stream.StreamSupport; |
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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.DoubleStream; |
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/** |
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* A generator of uniform pseudorandom values applicable for use in |
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* (among other contexts) isolated parallel computations that may |
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* generate subtasks. Class SplittableRandom supports methods for |
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jsr166 |
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* producing pseudorandom numbers of type {@code int}, {@code long}, |
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* and {@code double} with similar usages as for class |
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* {@link java.util.Random} but differs in the following ways: <ul> |
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* |
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* <li>Series of generated values pass the DieHarder suite testing |
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* independence and uniformity properties of random number generators. |
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* (Most recently validated with <a |
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* href="http://www.phy.duke.edu/~rgb/General/dieharder.php"> version |
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* 3.31.1</a>.) These tests validate only the methods for certain |
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* types and ranges, but similar properties are expected to hold, at |
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* least approximately, for others as well. </li> |
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* |
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* <li> Method {@link #split} constructs and returns a new |
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* SplittableRandom instance that shares no mutable state with the |
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1.7 |
* current instance. However, with very high probability, the |
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* values collectively generated by the two objects have the same |
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1.1 |
* statistical properties as if the same quantity of values were |
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* generated by a single thread using a single {@code |
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* SplittableRandom} object. </li> |
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* |
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* <li>Instances of SplittableRandom are <em>not</em> thread-safe. |
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* They are designed to be split, not shared, across threads. For |
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* example, a {@link java.util.concurrent.ForkJoinTask |
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* fork/join-style} computation using random numbers might include a |
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* construction of the form {@code new |
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* Subtask(aSplittableRandom.split()).fork()}. |
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* |
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* <li>This class provides additional methods for generating random |
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* streams, that employ the above techniques when used in {@code |
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* stream.parallel()} mode.</li> |
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* |
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* </ul> |
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* |
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* @author Guy Steele |
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* @author Doug Lea |
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* @since 1.8 |
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*/ |
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public class SplittableRandom { |
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/* |
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* File organization: First the non-public methods that constitute |
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* the main algorithm, then the main public methods, followed by |
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* some custom spliterator classes needed for stream methods. |
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* |
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* Credits: Primary algorithm and code by Guy Steele. Stream |
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* support methods by Doug Lea. Documentation jointly produced |
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* with additional help from Brian Goetz. |
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*/ |
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/* |
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* Implementation Overview. |
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* |
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* This algorithm was inspired by the "DotMix" algorithm by |
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* Leiserson, Schardl, and Sukha "Deterministic Parallel |
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* Random-Number Generation for Dynamic-Multithreading Platforms", |
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* PPoPP 2012, but improves and extends it in several ways. |
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* |
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* The primary update step (see method nextSeed()) is simply to |
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* add a constant ("gamma") to the current seed, modulo a prime |
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* ("George"). However, the nextLong and nextInt methods do not |
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* return this value, but instead the results of bit-mixing |
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* transformations that produce more uniformly distributed |
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* sequences. |
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* |
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* "George" is the otherwise nameless (because it cannot be |
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* represented) prime number 2^64+13. Using a prime number larger |
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* than can fit in a long ensures that all possible long values |
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* can occur, plus 13 others that just get skipped over when they |
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* are encountered; see method addGammaModGeorge. For this to |
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* work, initial gamma values must be at least 13. |
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* |
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* The value of gamma differs for each instance across a series of |
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* splits, and is generated using a slightly stripped-down variant |
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* of the same algorithm, but operating across calls to split(), |
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1.2 |
* not calls to nextSeed(): Each instance carries the state of |
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1.1 |
* this generator as nextSplit, and uses mix64(nextSplit) as its |
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* own gamma value. Computations of gammas themselves use a fixed |
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* constant as the second argument to the addGammaModGeorge |
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* function, GAMMA_GAMMA, a "genuinely random" number from a |
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* radioactive decay reading (obtained from |
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* http://www.fourmilab.ch/hotbits/) meeting the above range |
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* constraint. Using a fixed constant maintains the invariant that |
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* the value of gamma is the same for every instance that is at |
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* the same split-distance from their common root. (Note: there is |
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* nothing especially magic about obtaining this constant from a |
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* "truly random" physical source rather than just choosing one |
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* arbitrarily; using "hotbits" was merely an aesthetically pleasing |
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* choice. In either case, good statistical behavior of the |
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* algorithm should be, and was, verified by using the DieHarder |
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* test suite.) |
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* |
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* The mix64 bit-mixing function called by nextLong and other |
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* methods computes the same value as the "64-bit finalizer" |
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* function in Austin Appleby's MurmurHash3 algorithm. See |
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* http://code.google.com/p/smhasher/wiki/MurmurHash3 , which |
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* comments: "The constants for the finalizers were generated by a |
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* simple simulated-annealing algorithm, and both avalanche all |
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* bits of 'h' to within 0.25% bias." It also appears to work to |
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* use instead any of the variants proposed by David Stafford at |
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* http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html |
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* but these variants have not yet been tested as thoroughly |
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* in the context of the implementation of SplittableRandom. |
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* |
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* The mix32 function used for nextInt just consists of two of the |
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* five lines of mix64; avalanche testing shows that the 64-bit result |
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* has its top 32 bits avalanched well, though not the bottom 32 bits. |
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* DieHarder tests show that it is adequate for generating one |
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* random int from the 64-bit result of nextSeed. |
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* |
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* Support for the default (no-argument) constructor relies on an |
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* AtomicLong (defaultSeedGenerator) to help perform the |
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* equivalent of a split of a statically constructed |
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* SplittableRandom. Unlike other cases, this split must be |
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* performed in a thread-safe manner. We use |
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* AtomicLong.compareAndSet as the (typically) most efficient |
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* mechanism. To bootstrap, we start off using System.nanotime(), |
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* and update using another "genuinely random" constant |
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* DEFAULT_SEED_GAMMA. The default constructor uses GAMMA_GAMMA, |
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* not 0, for its splitSeed argument (addGammaModGeorge(0, |
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* GAMMA_GAMMA) == GAMMA_GAMMA) to reflect that each is split from |
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* this root generator, even though the root is not explicitly |
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* represented as a SplittableRandom. |
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*/ |
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/** |
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* The "genuinely random" value for producing new gamma values. |
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* The value is arbitrary, subject to the requirement that it be |
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* greater or equal to 13. |
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*/ |
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private static final long GAMMA_GAMMA = 0xF2281E2DBA6606F3L; |
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/** |
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* The "genuinely random" seed update value for default constructors. |
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* The value is arbitrary, subject to the requirement that it be |
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* greater or equal to 13. |
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*/ |
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private static final long DEFAULT_SEED_GAMMA = 0xBD24B73A95FB84D9L; |
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/** |
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1.5 |
* The least non-zero value returned by nextDouble(). This value |
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1.7 |
* is scaled by a random value of 53 bits to produce a result. |
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1.5 |
*/ |
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private static final double DOUBLE_UNIT = 1.0 / (1L << 53); |
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/** |
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* The next seed for default constructors. |
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*/ |
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private static final AtomicLong defaultSeedGenerator = |
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new AtomicLong(System.nanoTime()); |
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/** |
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* The seed, updated only via method nextSeed. |
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*/ |
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private long seed; |
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/** |
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* The constant value added to seed (mod George) on each update. |
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*/ |
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private final long gamma; |
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/** |
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* The next seed to use for splits. Propagated using |
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* addGammaModGeorge across instances. |
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*/ |
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private final long nextSplit; |
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/** |
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* Adds the given gamma value, g, to the given seed value s, mod |
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* George (2^64+13). We regard s and g as unsigned values |
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* (ranging from 0 to 2^64-1). We add g to s either once or twice |
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* (mod George) as necessary to produce an (unsigned) result less |
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* than 2^64. We require that g must be at least 13. This |
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* guarantees that if (s+g) mod George >= 2^64 then (s+g+g) mod |
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* George < 2^64; thus we need only a conditional, not a loop, |
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* to be sure of getting a representable value. |
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* |
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* @param s a seed value |
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* @param g a gamma value, 13 <= g (as unsigned) |
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*/ |
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private static long addGammaModGeorge(long s, long g) { |
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long p = s + g; |
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if (Long.compareUnsigned(p, g) >= 0) |
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return p; |
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long q = p - 13L; |
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return (Long.compareUnsigned(p, 13L) >= 0) ? q : (q + g); |
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} |
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/** |
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* Returns a bit-mixed transformation of its argument. |
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* See above for explanation. |
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*/ |
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private static long mix64(long z) { |
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z ^= (z >>> 33); |
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z *= 0xff51afd7ed558ccdL; |
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z ^= (z >>> 33); |
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z *= 0xc4ceb9fe1a85ec53L; |
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z ^= (z >>> 33); |
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return z; |
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} |
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/** |
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* Returns a bit-mixed int transformation of its argument. |
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* See above for explanation. |
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*/ |
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private static int mix32(long z) { |
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z ^= (z >>> 33); |
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z *= 0xc4ceb9fe1a85ec53L; |
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return (int)(z >>> 32); |
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} |
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/** |
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1.7 |
* Internal constructor used by all other constructors and by |
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* method split. Establishes the initial seed for this instance, |
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* and uses the given splitSeed to establish gamma, as well as the |
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* nextSplit to use by this instance. The loop to skip ineligible |
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* gammas very rarely iterates, and does so at most 13 times. |
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*/ |
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private SplittableRandom(long seed, long splitSeed) { |
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this.seed = seed; |
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long s = splitSeed, g; |
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do { // ensure gamma >= 13, considered as an unsigned integer |
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s = addGammaModGeorge(s, GAMMA_GAMMA); |
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g = mix64(s); |
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} while (Long.compareUnsigned(g, 13L) < 0); |
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this.gamma = g; |
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this.nextSplit = s; |
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} |
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/** |
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* Updates in-place and returns seed. |
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* See above for explanation. |
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*/ |
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private long nextSeed() { |
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return seed = addGammaModGeorge(seed, gamma); |
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} |
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/** |
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* Atomically updates and returns next seed for default constructor. |
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dl |
1.1 |
*/ |
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private static long nextDefaultSeed() { |
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long oldSeed, newSeed; |
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do { |
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oldSeed = defaultSeedGenerator.get(); |
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newSeed = addGammaModGeorge(oldSeed, DEFAULT_SEED_GAMMA); |
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} while (!defaultSeedGenerator.compareAndSet(oldSeed, newSeed)); |
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return mix64(newSeed); |
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} |
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/* |
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* Internal 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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/** |
298 |
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* The form of nextLong used by LongStream Spliterators. If |
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* origin is greater than bound, acts as unbounded form of |
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* nextLong, else as bounded form. |
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* |
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* @param origin the least value, unless greater than bound |
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* @param bound the upper bound (exclusive), must not equal origin |
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* @return a pseudorandom value |
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*/ |
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final long internalNextLong(long origin, long bound) { |
307 |
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/* |
308 |
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* Four Cases: |
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* |
310 |
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* 1. If the arguments indicate unbounded form, act as |
311 |
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* nextLong(). |
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* |
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* 2. If the range is an exact power of two, apply the |
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* associated bit mask. |
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* |
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* 3. If the range is positive, loop to avoid potential bias |
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* when the implicit nextLong() bound (2<sup>64</sup>) is not |
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* evenly divisible by the range. The loop rejects candidates |
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* computed from otherwise over-represented values. The |
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* expected number of iterations under an ideal generator |
321 |
dl |
1.4 |
* varies from 1 to 2, depending on the bound. The loop itself |
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* takes an unlovable form. Because the first candidate is |
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* already available, we need a break-in-the-middle |
324 |
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* construction, which is concisely but cryptically performed |
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* within the while-condition of a body-less for loop. |
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dl |
1.1 |
* |
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* 4. Otherwise, the range cannot be represented as a positive |
328 |
dl |
1.4 |
* long. The loop repeatedly generates unbounded longs until |
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* obtaining a candidate meeting constraints (with an expected |
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* number of iterations of less than two). |
331 |
dl |
1.1 |
*/ |
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|
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long r = mix64(nextSeed()); |
334 |
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if (origin < bound) { |
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long n = bound - origin, m = n - 1; |
336 |
dl |
1.7 |
if ((n & m) == 0L) // power of two |
337 |
dl |
1.1 |
r = (r & m) + origin; |
338 |
dl |
1.7 |
else if (n > 0L) { // reject over-represented candidates |
339 |
dl |
1.1 |
for (long u = r >>> 1; // ensure nonnegative |
340 |
dl |
1.7 |
u + m - (r = u % n) < 0L; // rejection check |
341 |
dl |
1.1 |
u = mix64(nextSeed()) >>> 1) // retry |
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; |
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r += origin; |
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} |
345 |
dl |
1.7 |
else { // range not representable as long |
346 |
dl |
1.1 |
while (r < origin || r >= bound) |
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r = mix64(nextSeed()); |
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} |
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} |
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return r; |
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} |
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/** |
354 |
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* The form of nextInt used by IntStream Spliterators. |
355 |
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* Exactly the same as long version, except for types. |
356 |
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* |
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* @param origin the least value, unless greater than bound |
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* @param bound the upper bound (exclusive), must not equal origin |
359 |
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* @return a pseudorandom value |
360 |
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*/ |
361 |
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final int internalNextInt(int origin, int bound) { |
362 |
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|
int r = mix32(nextSeed()); |
363 |
|
|
if (origin < bound) { |
364 |
|
|
int n = bound - origin, m = n - 1; |
365 |
|
|
if ((n & m) == 0L) |
366 |
|
|
r = (r & m) + origin; |
367 |
|
|
else if (n > 0) { |
368 |
|
|
for (int u = r >>> 1; |
369 |
dl |
1.7 |
u + m - (r = u % n) < 0; |
370 |
dl |
1.1 |
u = mix32(nextSeed()) >>> 1) |
371 |
|
|
; |
372 |
|
|
r += origin; |
373 |
|
|
} |
374 |
|
|
else { |
375 |
|
|
while (r < origin || r >= bound) |
376 |
|
|
r = mix32(nextSeed()); |
377 |
|
|
} |
378 |
|
|
} |
379 |
|
|
return r; |
380 |
|
|
} |
381 |
|
|
|
382 |
|
|
/** |
383 |
|
|
* The form of nextDouble used by DoubleStream Spliterators. |
384 |
|
|
* |
385 |
|
|
* @param origin the least value, unless greater than bound |
386 |
|
|
* @param bound the upper bound (exclusive), must not equal origin |
387 |
|
|
* @return a pseudorandom value |
388 |
|
|
*/ |
389 |
|
|
final double internalNextDouble(double origin, double bound) { |
390 |
dl |
1.5 |
double r = (nextLong() >>> 11) * DOUBLE_UNIT; |
391 |
dl |
1.1 |
if (origin < bound) { |
392 |
|
|
r = r * (bound - origin) + origin; |
393 |
dl |
1.7 |
if (r >= bound) // correct for rounding |
394 |
dl |
1.1 |
r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
395 |
|
|
} |
396 |
|
|
return r; |
397 |
|
|
} |
398 |
|
|
|
399 |
|
|
/* ---------------- public methods ---------------- */ |
400 |
|
|
|
401 |
|
|
/** |
402 |
dl |
1.7 |
* Creates a new SplittableRandom instance using the specified |
403 |
|
|
* initial seed. SplittableRandom instances created with the same |
404 |
|
|
* seed generate identical sequences of values. |
405 |
dl |
1.1 |
* |
406 |
|
|
* @param seed the initial seed |
407 |
|
|
*/ |
408 |
|
|
public SplittableRandom(long seed) { |
409 |
|
|
this(seed, 0); |
410 |
|
|
} |
411 |
|
|
|
412 |
|
|
/** |
413 |
|
|
* Creates a new SplittableRandom instance that is likely to |
414 |
|
|
* generate sequences of values that are statistically independent |
415 |
|
|
* of those of any other instances in the current program; and |
416 |
|
|
* may, and typically does, vary across program invocations. |
417 |
|
|
*/ |
418 |
|
|
public SplittableRandom() { |
419 |
|
|
this(nextDefaultSeed(), GAMMA_GAMMA); |
420 |
|
|
} |
421 |
|
|
|
422 |
|
|
/** |
423 |
|
|
* Constructs and returns a new SplittableRandom instance that |
424 |
|
|
* shares no mutable state with this instance. However, with very |
425 |
|
|
* high probability, the set of values collectively generated by |
426 |
|
|
* the two objects has the same statistical properties as if the |
427 |
|
|
* same quantity of values were generated by a single thread using |
428 |
|
|
* a single SplittableRandom object. Either or both of the two |
429 |
|
|
* objects may be further split using the {@code split()} method, |
430 |
|
|
* and the same expected statistical properties apply to the |
431 |
|
|
* entire set of generators constructed by such recursive |
432 |
|
|
* splitting. |
433 |
|
|
* |
434 |
|
|
* @return the new SplittableRandom instance |
435 |
|
|
*/ |
436 |
|
|
public SplittableRandom split() { |
437 |
|
|
return new SplittableRandom(nextSeed(), nextSplit); |
438 |
|
|
} |
439 |
|
|
|
440 |
|
|
/** |
441 |
|
|
* Returns a pseudorandom {@code int} value. |
442 |
|
|
* |
443 |
dl |
1.7 |
* @return a pseudorandom {@code int} value |
444 |
dl |
1.1 |
*/ |
445 |
|
|
public int nextInt() { |
446 |
|
|
return mix32(nextSeed()); |
447 |
|
|
} |
448 |
|
|
|
449 |
|
|
/** |
450 |
dl |
1.7 |
* Returns a pseudorandom {@code int} value between zero (inclusive) |
451 |
dl |
1.1 |
* and the specified bound (exclusive). |
452 |
|
|
* |
453 |
|
|
* @param bound the bound on the random number to be returned. Must be |
454 |
|
|
* positive. |
455 |
dl |
1.7 |
* @return a pseudorandom {@code int} value between zero |
456 |
dl |
1.1 |
* (inclusive) and the bound (exclusive). |
457 |
dl |
1.7 |
* @throws IllegalArgumentException if the bound is less than zero |
458 |
dl |
1.1 |
*/ |
459 |
|
|
public int nextInt(int bound) { |
460 |
|
|
if (bound <= 0) |
461 |
|
|
throw new IllegalArgumentException("bound must be positive"); |
462 |
|
|
// Specialize internalNextInt for origin 0 |
463 |
|
|
int r = mix32(nextSeed()); |
464 |
|
|
int m = bound - 1; |
465 |
|
|
if ((bound & m) == 0L) // power of two |
466 |
|
|
r &= m; |
467 |
|
|
else { // reject over-represented candidates |
468 |
|
|
for (int u = r >>> 1; |
469 |
dl |
1.7 |
u + m - (r = u % bound) < 0; |
470 |
dl |
1.1 |
u = mix32(nextSeed()) >>> 1) |
471 |
|
|
; |
472 |
|
|
} |
473 |
|
|
return r; |
474 |
|
|
} |
475 |
|
|
|
476 |
|
|
/** |
477 |
|
|
* Returns a pseudorandom {@code int} value between the specified |
478 |
|
|
* origin (inclusive) and the specified bound (exclusive). |
479 |
|
|
* |
480 |
|
|
* @param origin the least value returned |
481 |
|
|
* @param bound the upper bound (exclusive) |
482 |
|
|
* @return a pseudorandom {@code int} value between the origin |
483 |
|
|
* (inclusive) and the bound (exclusive). |
484 |
dl |
1.7 |
* @throws IllegalArgumentException if {@code origin} is greater than |
485 |
dl |
1.1 |
* or equal to {@code bound} |
486 |
|
|
*/ |
487 |
|
|
public int nextInt(int origin, int bound) { |
488 |
|
|
if (origin >= bound) |
489 |
|
|
throw new IllegalArgumentException("bound must be greater than origin"); |
490 |
|
|
return internalNextInt(origin, bound); |
491 |
|
|
} |
492 |
|
|
|
493 |
|
|
/** |
494 |
|
|
* Returns a pseudorandom {@code long} value. |
495 |
|
|
* |
496 |
dl |
1.7 |
* @return a pseudorandom {@code long} value |
497 |
dl |
1.1 |
*/ |
498 |
|
|
public long nextLong() { |
499 |
|
|
return mix64(nextSeed()); |
500 |
|
|
} |
501 |
|
|
|
502 |
|
|
/** |
503 |
dl |
1.7 |
* Returns a pseudorandom {@code long} value between zero (inclusive) |
504 |
dl |
1.1 |
* and the specified bound (exclusive). |
505 |
|
|
* |
506 |
|
|
* @param bound the bound on the random number to be returned. Must be |
507 |
|
|
* positive. |
508 |
dl |
1.7 |
* @return a pseudorandom {@code long} value between zero |
509 |
dl |
1.1 |
* (inclusive) and the bound (exclusive). |
510 |
dl |
1.7 |
* @throws IllegalArgumentException if {@code bound} is less than zero |
511 |
dl |
1.1 |
*/ |
512 |
|
|
public long nextLong(long bound) { |
513 |
|
|
if (bound <= 0) |
514 |
|
|
throw new IllegalArgumentException("bound must be positive"); |
515 |
|
|
// Specialize internalNextLong for origin 0 |
516 |
|
|
long r = mix64(nextSeed()); |
517 |
|
|
long m = bound - 1; |
518 |
|
|
if ((bound & m) == 0L) // power of two |
519 |
|
|
r &= m; |
520 |
|
|
else { // reject over-represented candidates |
521 |
|
|
for (long u = r >>> 1; |
522 |
|
|
u + m - (r = u % bound) < 0L; |
523 |
|
|
u = mix64(nextSeed()) >>> 1) |
524 |
|
|
; |
525 |
|
|
} |
526 |
|
|
return r; |
527 |
|
|
} |
528 |
|
|
|
529 |
|
|
/** |
530 |
|
|
* Returns a pseudorandom {@code long} value between the specified |
531 |
|
|
* origin (inclusive) and the specified bound (exclusive). |
532 |
|
|
* |
533 |
|
|
* @param origin the least value returned |
534 |
|
|
* @param bound the upper bound (exclusive) |
535 |
|
|
* @return a pseudorandom {@code long} value between the origin |
536 |
|
|
* (inclusive) and the bound (exclusive). |
537 |
dl |
1.7 |
* @throws IllegalArgumentException if {@code origin} is greater than |
538 |
dl |
1.1 |
* or equal to {@code bound} |
539 |
|
|
*/ |
540 |
|
|
public long nextLong(long origin, long bound) { |
541 |
|
|
if (origin >= bound) |
542 |
|
|
throw new IllegalArgumentException("bound must be greater than origin"); |
543 |
|
|
return internalNextLong(origin, bound); |
544 |
|
|
} |
545 |
|
|
|
546 |
|
|
/** |
547 |
dl |
1.7 |
* Returns a pseudorandom {@code double} value between zero |
548 |
|
|
* (inclusive) and one (exclusive). |
549 |
dl |
1.1 |
* |
550 |
dl |
1.7 |
* @return a pseudorandom {@code double} value between zero |
551 |
|
|
* (inclusive) and one (exclusive) |
552 |
dl |
1.1 |
*/ |
553 |
|
|
public double nextDouble() { |
554 |
dl |
1.5 |
return (nextLong() >>> 11) * DOUBLE_UNIT; |
555 |
dl |
1.1 |
} |
556 |
|
|
|
557 |
|
|
/** |
558 |
|
|
* Returns a pseudorandom {@code double} value between 0.0 |
559 |
|
|
* (inclusive) and the specified bound (exclusive). |
560 |
|
|
* |
561 |
|
|
* @param bound the bound on the random number to be returned. Must be |
562 |
|
|
* positive. |
563 |
dl |
1.7 |
* @return a pseudorandom {@code double} value between zero |
564 |
dl |
1.1 |
* (inclusive) and the bound (exclusive). |
565 |
dl |
1.7 |
* @throws IllegalArgumentException if {@code bound} is less than zero |
566 |
dl |
1.1 |
*/ |
567 |
|
|
public double nextDouble(double bound) { |
568 |
dl |
1.7 |
if (!(bound > 0.0)) |
569 |
dl |
1.1 |
throw new IllegalArgumentException("bound must be positive"); |
570 |
|
|
double result = nextDouble() * bound; |
571 |
|
|
return (result < bound) ? result : // correct for rounding |
572 |
|
|
Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
573 |
|
|
} |
574 |
|
|
|
575 |
|
|
/** |
576 |
dl |
1.7 |
* Returns a pseudorandom {@code double} value between the specified |
577 |
dl |
1.1 |
* origin (inclusive) and bound (exclusive). |
578 |
|
|
* |
579 |
|
|
* @param origin the least value returned |
580 |
|
|
* @param bound the upper bound |
581 |
|
|
* @return a pseudorandom {@code double} value between the origin |
582 |
|
|
* (inclusive) and the bound (exclusive). |
583 |
|
|
* @throws IllegalArgumentException if {@code origin} is greater than |
584 |
|
|
* or equal to {@code bound} |
585 |
|
|
*/ |
586 |
|
|
public double nextDouble(double origin, double bound) { |
587 |
dl |
1.7 |
if (!(origin < bound)) |
588 |
dl |
1.1 |
throw new IllegalArgumentException("bound must be greater than origin"); |
589 |
|
|
return internalNextDouble(origin, bound); |
590 |
|
|
} |
591 |
|
|
|
592 |
|
|
// stream methods, coded in a way intended to better isolate for |
593 |
|
|
// maintenance purposes the small differences across forms. |
594 |
|
|
|
595 |
|
|
/** |
596 |
dl |
1.7 |
* Returns a stream producing the given {@code streamSize} number of |
597 |
dl |
1.1 |
* pseudorandom {@code int} values. |
598 |
|
|
* |
599 |
|
|
* @param streamSize the number of values to generate |
600 |
|
|
* @return a stream of pseudorandom {@code int} values |
601 |
|
|
* @throws IllegalArgumentException if {@code streamSize} is |
602 |
dl |
1.7 |
* less than zero |
603 |
dl |
1.1 |
*/ |
604 |
|
|
public IntStream ints(long streamSize) { |
605 |
|
|
if (streamSize < 0L) |
606 |
|
|
throw new IllegalArgumentException("negative Stream size"); |
607 |
|
|
return StreamSupport.intStream |
608 |
|
|
(new RandomIntsSpliterator |
609 |
|
|
(this, 0L, streamSize, Integer.MAX_VALUE, 0), |
610 |
|
|
false); |
611 |
|
|
} |
612 |
|
|
|
613 |
|
|
/** |
614 |
|
|
* Returns an effectively unlimited stream of pseudorandom {@code int} |
615 |
|
|
* values |
616 |
|
|
* |
617 |
|
|
* @implNote This method is implemented to be equivalent to {@code |
618 |
|
|
* ints(Long.MAX_VALUE)}. |
619 |
|
|
* |
620 |
|
|
* @return a stream of pseudorandom {@code int} values |
621 |
|
|
*/ |
622 |
|
|
public IntStream ints() { |
623 |
|
|
return StreamSupport.intStream |
624 |
|
|
(new RandomIntsSpliterator |
625 |
|
|
(this, 0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0), |
626 |
|
|
false); |
627 |
|
|
} |
628 |
|
|
|
629 |
|
|
/** |
630 |
dl |
1.7 |
* Returns a stream producing the given {@code streamSize} number of |
631 |
dl |
1.1 |
* pseudorandom {@code int} values, each conforming to the given |
632 |
|
|
* origin and bound. |
633 |
|
|
* |
634 |
|
|
* @param streamSize the number of values to generate |
635 |
|
|
* @param randomNumberOrigin the origin of each random value |
636 |
|
|
* @param randomNumberBound the bound of each random value |
637 |
|
|
* @return a stream of pseudorandom {@code int} values, |
638 |
dl |
1.7 |
* each with the given origin and bound. |
639 |
dl |
1.1 |
* @throws IllegalArgumentException if {@code streamSize} is |
640 |
dl |
1.7 |
* less than zero, or {@code randomNumberOrigin} |
641 |
dl |
1.1 |
* is greater than or equal to {@code randomNumberBound} |
642 |
|
|
*/ |
643 |
|
|
public IntStream ints(long streamSize, int randomNumberOrigin, |
644 |
|
|
int randomNumberBound) { |
645 |
|
|
if (streamSize < 0L) |
646 |
|
|
throw new IllegalArgumentException("negative Stream size"); |
647 |
|
|
if (randomNumberOrigin >= randomNumberBound) |
648 |
|
|
throw new IllegalArgumentException("bound must be greater than origin"); |
649 |
|
|
return StreamSupport.intStream |
650 |
|
|
(new RandomIntsSpliterator |
651 |
|
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
652 |
|
|
false); |
653 |
|
|
} |
654 |
|
|
|
655 |
|
|
/** |
656 |
|
|
* Returns an effectively unlimited stream of pseudorandom {@code |
657 |
|
|
* int} values, each conforming to the given origin and bound. |
658 |
|
|
* |
659 |
|
|
* @implNote This method is implemented to be equivalent to {@code |
660 |
|
|
* ints(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
661 |
|
|
* |
662 |
|
|
* @param randomNumberOrigin the origin of each random value |
663 |
|
|
* @param randomNumberBound the bound of each random value |
664 |
|
|
* @return a stream of pseudorandom {@code int} values, |
665 |
dl |
1.7 |
* each with the given origin and bound. |
666 |
dl |
1.1 |
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
667 |
|
|
* is greater than or equal to {@code randomNumberBound} |
668 |
|
|
*/ |
669 |
|
|
public IntStream ints(int randomNumberOrigin, int randomNumberBound) { |
670 |
|
|
if (randomNumberOrigin >= randomNumberBound) |
671 |
|
|
throw new IllegalArgumentException("bound must be greater than origin"); |
672 |
|
|
return StreamSupport.intStream |
673 |
|
|
(new RandomIntsSpliterator |
674 |
|
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
675 |
|
|
false); |
676 |
|
|
} |
677 |
|
|
|
678 |
|
|
/** |
679 |
dl |
1.7 |
* Returns a stream producing the given {@code streamSize} number of |
680 |
dl |
1.1 |
* pseudorandom {@code long} values. |
681 |
|
|
* |
682 |
|
|
* @param streamSize the number of values to generate |
683 |
dl |
1.7 |
* @return a stream of pseudorandom {@code long} values |
684 |
dl |
1.1 |
* @throws IllegalArgumentException if {@code streamSize} is |
685 |
dl |
1.7 |
* less than zero |
686 |
dl |
1.1 |
*/ |
687 |
|
|
public LongStream longs(long streamSize) { |
688 |
|
|
if (streamSize < 0L) |
689 |
|
|
throw new IllegalArgumentException("negative Stream size"); |
690 |
|
|
return StreamSupport.longStream |
691 |
|
|
(new RandomLongsSpliterator |
692 |
|
|
(this, 0L, streamSize, Long.MAX_VALUE, 0L), |
693 |
|
|
false); |
694 |
|
|
} |
695 |
|
|
|
696 |
|
|
/** |
697 |
|
|
* Returns an effectively unlimited stream of pseudorandom {@code long} |
698 |
|
|
* values. |
699 |
|
|
* |
700 |
|
|
* @implNote This method is implemented to be equivalent to {@code |
701 |
|
|
* longs(Long.MAX_VALUE)}. |
702 |
|
|
* |
703 |
|
|
* @return a stream of pseudorandom {@code long} values |
704 |
|
|
*/ |
705 |
|
|
public LongStream longs() { |
706 |
|
|
return StreamSupport.longStream |
707 |
|
|
(new RandomLongsSpliterator |
708 |
|
|
(this, 0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L), |
709 |
|
|
false); |
710 |
|
|
} |
711 |
|
|
|
712 |
|
|
/** |
713 |
dl |
1.7 |
* Returns a stream producing the given {@code streamSize} number of |
714 |
dl |
1.1 |
* pseudorandom {@code long} values, each conforming to the |
715 |
|
|
* given origin and bound. |
716 |
|
|
* |
717 |
|
|
* @param streamSize the number of values to generate |
718 |
|
|
* @param randomNumberOrigin the origin of each random value |
719 |
|
|
* @param randomNumberBound the bound of each random value |
720 |
|
|
* @return a stream of pseudorandom {@code long} values, |
721 |
dl |
1.7 |
* each with the given origin and bound. |
722 |
dl |
1.1 |
* @throws IllegalArgumentException if {@code streamSize} is |
723 |
dl |
1.7 |
* less than zero, or {@code randomNumberOrigin} |
724 |
dl |
1.1 |
* is greater than or equal to {@code randomNumberBound} |
725 |
|
|
*/ |
726 |
|
|
public LongStream longs(long streamSize, long randomNumberOrigin, |
727 |
|
|
long randomNumberBound) { |
728 |
|
|
if (streamSize < 0L) |
729 |
|
|
throw new IllegalArgumentException("negative Stream size"); |
730 |
|
|
if (randomNumberOrigin >= randomNumberBound) |
731 |
|
|
throw new IllegalArgumentException("bound must be greater than origin"); |
732 |
|
|
return StreamSupport.longStream |
733 |
|
|
(new RandomLongsSpliterator |
734 |
|
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
735 |
|
|
false); |
736 |
|
|
} |
737 |
|
|
|
738 |
|
|
/** |
739 |
|
|
* Returns an effectively unlimited stream of pseudorandom {@code |
740 |
|
|
* long} values, each conforming to the given origin and bound. |
741 |
|
|
* |
742 |
|
|
* @implNote This method is implemented to be equivalent to {@code |
743 |
|
|
* longs(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
744 |
|
|
* |
745 |
|
|
* @param randomNumberOrigin the origin of each random value |
746 |
|
|
* @param randomNumberBound the bound of each random value |
747 |
|
|
* @return a stream of pseudorandom {@code long} values, |
748 |
dl |
1.7 |
* each with the given origin and bound. |
749 |
dl |
1.1 |
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
750 |
|
|
* is greater than or equal to {@code randomNumberBound} |
751 |
|
|
*/ |
752 |
|
|
public LongStream longs(long randomNumberOrigin, long randomNumberBound) { |
753 |
|
|
if (randomNumberOrigin >= randomNumberBound) |
754 |
|
|
throw new IllegalArgumentException("bound must be greater than origin"); |
755 |
|
|
return StreamSupport.longStream |
756 |
|
|
(new RandomLongsSpliterator |
757 |
|
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
758 |
|
|
false); |
759 |
|
|
} |
760 |
|
|
|
761 |
|
|
/** |
762 |
dl |
1.7 |
* Returns a stream producing the given {@code streamSize} number of |
763 |
|
|
* pseudorandom {@code double} values, each between zero |
764 |
|
|
* (inclusive) and one (exclusive). |
765 |
dl |
1.1 |
* |
766 |
|
|
* @param streamSize the number of values to generate |
767 |
|
|
* @return a stream of {@code double} values |
768 |
|
|
* @throws IllegalArgumentException if {@code streamSize} is |
769 |
dl |
1.7 |
* less than zero |
770 |
dl |
1.1 |
*/ |
771 |
|
|
public DoubleStream doubles(long streamSize) { |
772 |
|
|
if (streamSize < 0L) |
773 |
|
|
throw new IllegalArgumentException("negative Stream size"); |
774 |
|
|
return StreamSupport.doubleStream |
775 |
|
|
(new RandomDoublesSpliterator |
776 |
|
|
(this, 0L, streamSize, Double.MAX_VALUE, 0.0), |
777 |
|
|
false); |
778 |
|
|
} |
779 |
|
|
|
780 |
|
|
/** |
781 |
|
|
* Returns an effectively unlimited stream of pseudorandom {@code |
782 |
dl |
1.7 |
* double} values, each between zero (inclusive) and one |
783 |
|
|
* (exclusive). |
784 |
dl |
1.1 |
* |
785 |
|
|
* @implNote This method is implemented to be equivalent to {@code |
786 |
|
|
* doubles(Long.MAX_VALUE)}. |
787 |
|
|
* |
788 |
|
|
* @return a stream of pseudorandom {@code double} values |
789 |
|
|
*/ |
790 |
|
|
public DoubleStream doubles() { |
791 |
|
|
return StreamSupport.doubleStream |
792 |
|
|
(new RandomDoublesSpliterator |
793 |
|
|
(this, 0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0), |
794 |
|
|
false); |
795 |
|
|
} |
796 |
|
|
|
797 |
|
|
/** |
798 |
dl |
1.7 |
* Returns a stream producing the given {@code streamSize} number of |
799 |
dl |
1.1 |
* pseudorandom {@code double} values, each conforming to the |
800 |
|
|
* given origin and bound. |
801 |
|
|
* |
802 |
|
|
* @param streamSize the number of values to generate |
803 |
|
|
* @param randomNumberOrigin the origin of each random value |
804 |
|
|
* @param randomNumberBound the bound of each random value |
805 |
|
|
* @return a stream of pseudorandom {@code double} values, |
806 |
|
|
* each with the given origin and bound. |
807 |
|
|
* @throws IllegalArgumentException if {@code streamSize} is |
808 |
|
|
* less than zero. |
809 |
|
|
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
810 |
|
|
* is greater than or equal to {@code randomNumberBound} |
811 |
|
|
*/ |
812 |
|
|
public DoubleStream doubles(long streamSize, double randomNumberOrigin, |
813 |
|
|
double randomNumberBound) { |
814 |
|
|
if (streamSize < 0L) |
815 |
|
|
throw new IllegalArgumentException("negative Stream size"); |
816 |
dl |
1.7 |
if (!(randomNumberOrigin < randomNumberBound)) |
817 |
dl |
1.1 |
throw new IllegalArgumentException("bound must be greater than origin"); |
818 |
|
|
return StreamSupport.doubleStream |
819 |
|
|
(new RandomDoublesSpliterator |
820 |
|
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
821 |
|
|
false); |
822 |
|
|
} |
823 |
|
|
|
824 |
|
|
/** |
825 |
|
|
* Returns an effectively unlimited stream of pseudorandom {@code |
826 |
|
|
* double} values, each conforming to the given origin and bound. |
827 |
|
|
* |
828 |
|
|
* @implNote This method is implemented to be equivalent to {@code |
829 |
|
|
* doubles(Long.MAX_VALUE, randomNumberOrigin, randomNumberBound)}. |
830 |
|
|
* |
831 |
|
|
* @param randomNumberOrigin the origin of each random value |
832 |
|
|
* @param randomNumberBound the bound of each random value |
833 |
|
|
* @return a stream of pseudorandom {@code double} values, |
834 |
|
|
* each with the given origin and bound. |
835 |
|
|
* @throws IllegalArgumentException if {@code randomNumberOrigin} |
836 |
|
|
* is greater than or equal to {@code randomNumberBound} |
837 |
|
|
*/ |
838 |
|
|
public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) { |
839 |
dl |
1.7 |
if (!(randomNumberOrigin < randomNumberBound)) |
840 |
dl |
1.1 |
throw new IllegalArgumentException("bound must be greater than origin"); |
841 |
|
|
return StreamSupport.doubleStream |
842 |
|
|
(new RandomDoublesSpliterator |
843 |
|
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
844 |
|
|
false); |
845 |
|
|
} |
846 |
|
|
|
847 |
|
|
/** |
848 |
|
|
* Spliterator for int streams. We multiplex the four int |
849 |
dl |
1.7 |
* versions into one class by treating a bound less than origin as |
850 |
dl |
1.1 |
* unbounded, and also by treating "infinite" as equivalent to |
851 |
|
|
* Long.MAX_VALUE. For splits, it uses the standard divide-by-two |
852 |
|
|
* approach. The long and double versions of this class are |
853 |
|
|
* identical except for types. |
854 |
|
|
*/ |
855 |
|
|
static class RandomIntsSpliterator implements Spliterator.OfInt { |
856 |
|
|
final SplittableRandom rng; |
857 |
|
|
long index; |
858 |
|
|
final long fence; |
859 |
|
|
final int origin; |
860 |
|
|
final int bound; |
861 |
|
|
RandomIntsSpliterator(SplittableRandom rng, long index, long fence, |
862 |
|
|
int origin, int bound) { |
863 |
|
|
this.rng = rng; this.index = index; this.fence = fence; |
864 |
|
|
this.origin = origin; this.bound = bound; |
865 |
|
|
} |
866 |
|
|
|
867 |
|
|
public RandomIntsSpliterator trySplit() { |
868 |
|
|
long i = index, m = (i + fence) >>> 1; |
869 |
|
|
return (m <= i) ? null : |
870 |
|
|
new RandomIntsSpliterator(rng.split(), i, index = m, origin, bound); |
871 |
|
|
} |
872 |
|
|
|
873 |
|
|
public long estimateSize() { |
874 |
|
|
return fence - index; |
875 |
|
|
} |
876 |
|
|
|
877 |
|
|
public int characteristics() { |
878 |
|
|
return (Spliterator.SIZED | Spliterator.SUBSIZED | |
879 |
dl |
1.4 |
Spliterator.NONNULL | Spliterator.IMMUTABLE); |
880 |
dl |
1.1 |
} |
881 |
|
|
|
882 |
|
|
public boolean tryAdvance(IntConsumer consumer) { |
883 |
|
|
if (consumer == null) throw new NullPointerException(); |
884 |
|
|
long i = index, f = fence; |
885 |
|
|
if (i < f) { |
886 |
|
|
consumer.accept(rng.internalNextInt(origin, bound)); |
887 |
|
|
index = i + 1; |
888 |
|
|
return true; |
889 |
|
|
} |
890 |
|
|
return false; |
891 |
|
|
} |
892 |
|
|
|
893 |
|
|
public void forEachRemaining(IntConsumer consumer) { |
894 |
|
|
if (consumer == null) throw new NullPointerException(); |
895 |
|
|
long i = index, f = fence; |
896 |
|
|
if (i < f) { |
897 |
|
|
index = f; |
898 |
|
|
int o = origin, b = bound; |
899 |
|
|
do { |
900 |
|
|
consumer.accept(rng.internalNextInt(o, b)); |
901 |
|
|
} while (++i < f); |
902 |
|
|
} |
903 |
|
|
} |
904 |
|
|
} |
905 |
|
|
|
906 |
|
|
/** |
907 |
|
|
* Spliterator for long streams. |
908 |
|
|
*/ |
909 |
|
|
static class RandomLongsSpliterator implements Spliterator.OfLong { |
910 |
|
|
final SplittableRandom rng; |
911 |
|
|
long index; |
912 |
|
|
final long fence; |
913 |
|
|
final long origin; |
914 |
|
|
final long bound; |
915 |
|
|
RandomLongsSpliterator(SplittableRandom rng, long index, long fence, |
916 |
|
|
long origin, long bound) { |
917 |
|
|
this.rng = rng; this.index = index; this.fence = fence; |
918 |
|
|
this.origin = origin; this.bound = bound; |
919 |
|
|
} |
920 |
|
|
|
921 |
|
|
public RandomLongsSpliterator trySplit() { |
922 |
|
|
long i = index, m = (i + fence) >>> 1; |
923 |
|
|
return (m <= i) ? null : |
924 |
|
|
new RandomLongsSpliterator(rng.split(), i, index = m, origin, bound); |
925 |
|
|
} |
926 |
|
|
|
927 |
|
|
public long estimateSize() { |
928 |
|
|
return fence - index; |
929 |
|
|
} |
930 |
|
|
|
931 |
|
|
public int characteristics() { |
932 |
|
|
return (Spliterator.SIZED | Spliterator.SUBSIZED | |
933 |
dl |
1.4 |
Spliterator.NONNULL | Spliterator.IMMUTABLE); |
934 |
dl |
1.1 |
} |
935 |
|
|
|
936 |
|
|
public boolean tryAdvance(LongConsumer consumer) { |
937 |
|
|
if (consumer == null) throw new NullPointerException(); |
938 |
|
|
long i = index, f = fence; |
939 |
|
|
if (i < f) { |
940 |
|
|
consumer.accept(rng.internalNextLong(origin, bound)); |
941 |
|
|
index = i + 1; |
942 |
|
|
return true; |
943 |
|
|
} |
944 |
|
|
return false; |
945 |
|
|
} |
946 |
|
|
|
947 |
|
|
public void forEachRemaining(LongConsumer consumer) { |
948 |
|
|
if (consumer == null) throw new NullPointerException(); |
949 |
|
|
long i = index, f = fence; |
950 |
|
|
if (i < f) { |
951 |
|
|
index = f; |
952 |
|
|
long o = origin, b = bound; |
953 |
|
|
do { |
954 |
|
|
consumer.accept(rng.internalNextLong(o, b)); |
955 |
|
|
} while (++i < f); |
956 |
|
|
} |
957 |
|
|
} |
958 |
|
|
|
959 |
|
|
} |
960 |
|
|
|
961 |
|
|
/** |
962 |
|
|
* Spliterator for double streams. |
963 |
|
|
*/ |
964 |
|
|
static class RandomDoublesSpliterator implements Spliterator.OfDouble { |
965 |
|
|
final SplittableRandom rng; |
966 |
|
|
long index; |
967 |
|
|
final long fence; |
968 |
|
|
final double origin; |
969 |
|
|
final double bound; |
970 |
|
|
RandomDoublesSpliterator(SplittableRandom rng, long index, long fence, |
971 |
|
|
double origin, double bound) { |
972 |
|
|
this.rng = rng; this.index = index; this.fence = fence; |
973 |
|
|
this.origin = origin; this.bound = bound; |
974 |
|
|
} |
975 |
|
|
|
976 |
|
|
public RandomDoublesSpliterator trySplit() { |
977 |
|
|
long i = index, m = (i + fence) >>> 1; |
978 |
|
|
return (m <= i) ? null : |
979 |
|
|
new RandomDoublesSpliterator(rng.split(), i, index = m, origin, bound); |
980 |
|
|
} |
981 |
|
|
|
982 |
|
|
public long estimateSize() { |
983 |
|
|
return fence - index; |
984 |
|
|
} |
985 |
|
|
|
986 |
|
|
public int characteristics() { |
987 |
|
|
return (Spliterator.SIZED | Spliterator.SUBSIZED | |
988 |
dl |
1.4 |
Spliterator.NONNULL | Spliterator.IMMUTABLE); |
989 |
dl |
1.1 |
} |
990 |
|
|
|
991 |
|
|
public boolean tryAdvance(DoubleConsumer consumer) { |
992 |
|
|
if (consumer == null) throw new NullPointerException(); |
993 |
|
|
long i = index, f = fence; |
994 |
|
|
if (i < f) { |
995 |
|
|
consumer.accept(rng.internalNextDouble(origin, bound)); |
996 |
|
|
index = i + 1; |
997 |
|
|
return true; |
998 |
|
|
} |
999 |
|
|
return false; |
1000 |
|
|
} |
1001 |
|
|
|
1002 |
|
|
public void forEachRemaining(DoubleConsumer consumer) { |
1003 |
|
|
if (consumer == null) throw new NullPointerException(); |
1004 |
|
|
long i = index, f = fence; |
1005 |
|
|
if (i < f) { |
1006 |
|
|
index = f; |
1007 |
|
|
double o = origin, b = bound; |
1008 |
|
|
do { |
1009 |
|
|
consumer.accept(rng.internalNextDouble(o, b)); |
1010 |
|
|
} while (++i < f); |
1011 |
|
|
} |
1012 |
|
|
} |
1013 |
|
|
} |
1014 |
|
|
|
1015 |
|
|
} |