--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/newrandom/SplittableRng.java Thu May 23 16:45:56 2019 -0400
@@ -0,0 +1,192 @@
+/*
+ * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
+ * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ */
+// package java.util;
+
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+import java.util.stream.IntStream;
+import java.util.stream.LongStream;
+import java.util.stream.DoubleStream;
+
+/**
+ * This interface is designed to provide a common protocol for objects
+ * that generate sequences of pseudorandom numbers (or Boolean values)
+ * and furthermore can be <it>split</it> into two objects (the original
+ * one and a new one) each of which obey that same protocol (and therefore
+ * can be recursively split indefinitely).
+ *
+ * <p>Ideally, all {@code SplittableRNG} objects produced by recursive
+ * splitting from a single original {@code SplittableRNG} object are
+ * statistically independent of one another and individually uniform.
+ * Therefore we would expect the set of values collectively generated
+ * by a set of such objects to have the same statistical properties as
+ * if the same quantity of values were generated by a single thread
+ * using a single {@code SplittableRNG} object. In practice, one must
+ * settle for some approximation to independence and uniformity.
+ *
+ * <p>Methods are provided to perform a single splitting operation and
+ * also to produce a stream of generators split off from the original
+ * (by either iterative or recursive splitting, or a combination).
+ *
+ * <p>An implementation of the {@code SplittableRng} interface must provide
+ * concrete definitions for the methods {@code nextInt()}, {@code nextLong},
+ * {@code period()}, {@code split()}, {@code split(SplittableRng)},
+ * {@code splits()}, {@code splits(long)}, {@code splits(SplittableRng)},
+ * and {@code splits(long, SplittableRng)}. Perhaps the most convenient
+ * way to implement this interface is to extend the abstract class
+ * {@link java.util.AbstractSplittableRng}.
+ *
+ * <p>Objects that implement {@code java.util.SplittableRNG} are
+ * typically not cryptographically secure. Consider instead using
+ * {@link java.security.SecureRandom} to get a cryptographically
+ * secure pseudo-random number generator for use by
+ * security-sensitive applications.
+ *
+ * @author Guy Steele
+ * @since 1.9
+ */
+interface SplittableRng extends StreamableRng {
+
+ /**
+ * Returns a new pseudorandom number generator, split off from
+ * this one, that implements the {@code Rng} and {@code SplittableRng}
+ * interfaces.
+ *
+ * This pseudorandom number generator may be used as a source of
+ * pseudorandom bits used to initialize the state the new one.
+ *
+ * @return a new object that implements the {@code Rng} and
+ * {@code SplittableRng} interfaces
+ */
+ SplittableRng split();
+
+ /**
+ * Returns a new pseudorandom number generator, split off from
+ * this one, that implements the {@code Rng} and {@code SplittableRng}
+ * interfaces.
+ *
+ * @param source a {@code SplittableRng} instance to be used instead
+ * of this one as a source of pseudorandom bits used to
+ * initialize the state of the new ones.
+ *
+ * @return an object that implements the {@code Rng} and
+ * {@code SplittableRng} interfaces
+ */
+ SplittableRng split(SplittableRng source);
+
+ /**
+ * Returns an effectively unlimited stream of new pseudorandom
+ * number generators, each of which implements the {@code SplittableRng}
+ * interface.
+ *
+ * This pseudorandom number generator may be used as a source of
+ * pseudorandom bits used to initialize the state the new ones.
+ *
+ * @implNote It is permitted to implement this method in a manner
+ * equivalent to {@code splits(Long.MAX_VALUE)}.
+ *
+ * @return a stream of {@code SplittableRng} objects
+ */
+ default Stream<SplittableRng> splits() {
+ return this.splits(this);
+ }
+
+ /**
+ * Returns a stream producing the given {@code streamSize} number of
+ * new pseudorandom number generators, each of which implements the
+ * {@code SplittableRng} interface.
+ *
+ * This pseudorandom number generator may be used as a source of
+ * pseudorandom bits used to initialize the state the new ones.
+ *
+ * @param streamSize the number of values to generate
+ * @return a stream of {@code SplittableRng} objects
+ * @throws IllegalArgumentException if {@code streamSize} is
+ * less than zero
+ */
+ Stream<SplittableRng> splits(long streamSize);
+
+ /**
+ * Returns an effectively unlimited stream of new pseudorandom
+ * number generators, each of which implements the {@code SplittableRng}
+ * interface.
+ *
+ * @implNote It is permitted to implement this method in a manner
+ * equivalent to {@code splits(Long.MAX_VALUE, source)}.
+ *
+ * @param source a {@code SplittableRng} instance to be used instead
+ * of this one as a source of pseudorandom bits used to
+ * initialize the state of the new ones.
+ *
+ * @return a stream of {@code SplittableRng} objects
+ */
+ Stream<SplittableRng> splits(SplittableRng source);
+
+ /**
+ * Returns a stream producing the given {@code streamSize} number of
+ * new pseudorandom number generators, each of which implements the
+ * {@code SplittableRng} interface.
+ *
+ * @param streamSize the number of values to generate
+ * @param source a {@code SplittableRng} instance to be used instead
+ * of this one as a source of pseudorandom bits used to
+ * initialize the state of the new ones.
+ * @return a stream of {@code SplittableRng} objects
+ * @throws IllegalArgumentException if {@code streamSize} is
+ * less than zero
+ */
+ Stream<SplittableRng> splits(long streamSize, SplittableRng source);
+
+ /**
+ * Returns an effectively unlimited stream of new pseudorandom
+ * number generators, each of which implements the {@code Rng}
+ * interface. Ideally the generators in the stream will appear
+ * to be statistically independent.
+ *
+ * @implNote The default implementation calls {@code splits()}.
+ *
+ * @return a stream of objects that implement the {@code Rng} interface
+ */
+ default Stream<Rng> rngs() {
+ return this.splits().map(x -> (Rng)x);
+ }
+
+ /**
+ * Returns a stream producing the given {@code streamSize} number of
+ * new pseudorandom number generators, each of which implements the
+ * {@code Rng} interface. Ideally the generators in the stream will
+ * appear to be statistically independent.
+ *
+ * @implNote The default implementation calls {@code splits(streamSize)}.
+ *
+ * @param streamSize the number of generators to generate
+ * @return a stream of objects that implement the {@code Rng} interface
+ * @throws IllegalArgumentException if {@code streamSize} is
+ * less than zero
+ */
+ default Stream<Rng> rngs(long streamSize) {
+ return this.splits(streamSize).map(x -> (Rng)x);
+ }
+}