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package java.util; |
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import java.security.SecureRandom; |
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import java.net.NetworkInterface; |
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import java.util.Enumeration; |
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import java.util.concurrent.atomic.AtomicLong; |
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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.function.DoubleConsumer; |
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import java.util.stream.StreamSupport; |
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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.DoubleStream; |
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import java.util.stream.StreamSupport; |
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/** |
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* A generator of uniform pseudorandom values applicable for use in |
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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. The <em>period</em> |
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* (length of any series of generated values before it repeats) is at |
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* least 2<sup>64</sup>. </li> |
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* least 2<sup>64</sup>. |
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* |
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* <li> Method {@link #split} constructs and returns a new |
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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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* 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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* 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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* SplittableRandom} object. |
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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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* |
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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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* stream.parallel()} mode. |
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* |
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* </ul> |
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* |
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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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> |
public final class SplittableRandom { |
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|
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/* |
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* Implementation Overview. |
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* For nextLong, the mix64 function is based on David Stafford's |
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* (http://zimbry.blogspot.com/2011/09/better-bit-mixing-improving-on.html) |
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* "Mix13" variant of the "64-bit finalizer" function in Austin |
112 |
< |
* Appleby's MurmurHash3 algorithm See |
113 |
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* http://code.google.com/p/smhasher/wiki/MurmurHash3 . The mix32 |
112 |
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* Appleby's MurmurHash3 algorithm (see |
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* http://code.google.com/p/smhasher/wiki/MurmurHash3). The mix32 |
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* function is based on Stafford's Mix04 mix function, but returns |
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* the upper 32 bits cast as int. |
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* |
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* other cases, this split must be performed in a thread-safe |
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* manner, so we use an AtomicLong to represent the seed rather |
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* than use an explicit SplittableRandom. To bootstrap the |
142 |
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* defaultGen, we start off using a seed based on current time and |
143 |
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* network interface address unless the java.util.secureRandomSeed |
144 |
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* property is set. This serves as a slimmed-down (and insecure) |
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* variant of SecureRandom that also avoids stalls that may occur |
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* when using /dev/random. |
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* defaultGen, we start off using a seed based on current time |
143 |
> |
* unless the java.util.secureRandomSeed property is set. This |
144 |
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* serves as a slimmed-down (and insecure) variant of SecureRandom |
145 |
> |
* that also avoids stalls that may occur when using /dev/random. |
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* |
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* It is a relatively simple matter to apply the basic design here |
148 |
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* to use 128 bit seeds. However, emulating 128bit arithmetic and |
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* The least non-zero value returned by nextDouble(). This value |
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* is scaled by a random value of 53 bits to produce a result. |
166 |
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*/ |
167 |
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private static final double DOUBLE_ULP = 1.0 / (1L << 53); |
167 |
> |
private static final double DOUBLE_UNIT = 0x1.0p-53; // 1.0 / (1L << 53); |
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/** |
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* The seed. Updated only via method nextSeed. |
188 |
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* Computes Stafford variant 13 of 64bit mix function. |
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*/ |
190 |
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private static long mix64(long z) { |
191 |
< |
z *= 0xbf58476d1ce4e5b9L; |
196 |
< |
z = (z ^ (z >>> 32)) * 0x94d049bb133111ebL; |
197 |
< |
return z ^ (z >>> 32); |
198 |
< |
} |
199 |
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|
200 |
< |
private static long xmix64(long z) { |
201 |
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z *= 0xbf58476d1ce4e5b9L; |
191 |
> |
z = (z ^ (z >>> 30)) * 0xbf58476d1ce4e5b9L; |
192 |
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z = (z ^ (z >>> 27)) * 0x94d049bb133111ebL; |
193 |
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return z ^ (z >>> 31); |
194 |
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} |
197 |
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* Returns the 32 high bits of Stafford variant 4 mix64 function as int. |
198 |
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*/ |
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private static int mix32(long z) { |
200 |
< |
z *= 0x62a9d9ed799705f5L; |
200 |
> |
z = (z ^ (z >>> 33)) * 0x62a9d9ed799705f5L; |
201 |
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return (int)(((z ^ (z >>> 28)) * 0xcb24d0a5c88c35b3L) >>> 32); |
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} |
203 |
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|
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* Returns the gamma value to use for a new split instance. |
206 |
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*/ |
207 |
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private static long mixGamma(long z) { |
208 |
< |
z *= 0xff51afd7ed558ccdL; // MurmurHash3 mix constants |
208 |
> |
z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL; // MurmurHash3 mix constants |
209 |
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z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L; |
210 |
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z = (z ^ (z >>> 33)) | 1L; // force to be odd |
211 |
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int n = Long.bitCount(z ^ (z >>> 1)); // ensure enough transitions |
225 |
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private static final AtomicLong defaultGen = new AtomicLong(initialSeed()); |
226 |
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227 |
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private static long initialSeed() { |
228 |
< |
String pp = java.security.AccessController.doPrivileged( |
229 |
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new sun.security.action.GetPropertyAction( |
230 |
< |
"java.util.secureRandomSeed")); |
231 |
< |
if (pp != null && pp.equalsIgnoreCase("true")) { |
228 |
> |
if (java.security.AccessController.doPrivileged( |
229 |
> |
new java.security.PrivilegedAction<Boolean>() { |
230 |
> |
public Boolean run() { |
231 |
> |
return Boolean.getBoolean("java.util.secureRandomSeed"); |
232 |
> |
}})) { |
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byte[] seedBytes = java.security.SecureRandom.getSeed(8); |
234 |
< |
long s = (long)(seedBytes[0]) & 0xffL; |
234 |
> |
long s = (long)seedBytes[0] & 0xffL; |
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for (int i = 1; i < 8; ++i) |
236 |
< |
s = (s << 8) | ((long)(seedBytes[i]) & 0xffL); |
236 |
> |
s = (s << 8) | ((long)seedBytes[i] & 0xffL); |
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return s; |
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} |
239 |
< |
long h = 0L; |
249 |
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try { |
250 |
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Enumeration<NetworkInterface> ifcs = |
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NetworkInterface.getNetworkInterfaces(); |
252 |
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boolean retry = false; // retry once if getHardwareAddress is null |
253 |
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while (ifcs.hasMoreElements()) { |
254 |
< |
NetworkInterface ifc = ifcs.nextElement(); |
255 |
< |
if (!ifc.isVirtual()) { // skip fake addresses |
256 |
< |
byte[] bs = ifc.getHardwareAddress(); |
257 |
< |
if (bs != null) { |
258 |
< |
int n = bs.length; |
259 |
< |
int m = Math.min(n >>> 1, 4); |
260 |
< |
for (int i = 0; i < m; ++i) |
261 |
< |
h = (h << 16) ^ (bs[i] << 8) ^ bs[n-1-i]; |
262 |
< |
if (m < 4) |
263 |
< |
h = (h << 8) ^ bs[n-1-m]; |
264 |
< |
h = mix64(h); |
265 |
< |
break; |
266 |
< |
} |
267 |
< |
else if (!retry) |
268 |
< |
retry = true; |
269 |
< |
else |
270 |
< |
break; |
271 |
< |
} |
272 |
< |
} |
273 |
< |
} catch (Exception ignore) { |
274 |
< |
} |
275 |
< |
return (h ^ mix64(System.currentTimeMillis()) ^ |
239 |
> |
return (mix64(System.currentTimeMillis()) ^ |
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mix64(System.nanoTime())); |
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} |
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|
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// IllegalArgumentException messages |
244 |
< |
static final String BadBound = "bound must be positive"; |
245 |
< |
static final String BadRange = "bound must be greater than origin"; |
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static final String BadSize = "size must be non-negative"; |
244 |
> |
static final String BAD_BOUND = "bound must be positive"; |
245 |
> |
static final String BAD_RANGE = "bound must be greater than origin"; |
246 |
> |
static final String BAD_SIZE = "size must be non-negative"; |
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|
248 |
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/* |
249 |
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* Internal versions of nextX methods used by streams, as well as |
345 |
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* @return a pseudorandom value |
346 |
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*/ |
347 |
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final double internalNextDouble(double origin, double bound) { |
348 |
< |
double r = (nextLong() >>> 11) * DOUBLE_ULP; |
348 |
> |
double r = (nextLong() >>> 11) * DOUBLE_UNIT; |
349 |
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if (origin < bound) { |
350 |
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r = r * (bound - origin) + origin; |
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if (r >= bound) // correct for rounding |
374 |
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* may, and typically does, vary across program invocations. |
375 |
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*/ |
376 |
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public SplittableRandom() { // emulate defaultGen.split() |
377 |
< |
long s = defaultGen.getAndAdd(2*GOLDEN_GAMMA); |
377 |
> |
long s = defaultGen.getAndAdd(2 * GOLDEN_GAMMA); |
378 |
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this.seed = mix64(s); |
379 |
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this.gamma = mixGamma(s + GOLDEN_GAMMA); |
380 |
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} |
417 |
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*/ |
418 |
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public int nextInt(int bound) { |
419 |
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if (bound <= 0) |
420 |
< |
throw new IllegalArgumentException(BadBound); |
420 |
> |
throw new IllegalArgumentException(BAD_BOUND); |
421 |
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// Specialize internalNextInt for origin 0 |
422 |
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int r = mix32(nextSeed()); |
423 |
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int m = bound - 1; |
445 |
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*/ |
446 |
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public int nextInt(int origin, int bound) { |
447 |
|
if (origin >= bound) |
448 |
< |
throw new IllegalArgumentException(BadRange); |
448 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
449 |
|
return internalNextInt(origin, bound); |
450 |
|
} |
451 |
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|
469 |
|
*/ |
470 |
|
public long nextLong(long bound) { |
471 |
|
if (bound <= 0) |
472 |
< |
throw new IllegalArgumentException(BadBound); |
472 |
> |
throw new IllegalArgumentException(BAD_BOUND); |
473 |
|
// Specialize internalNextLong for origin 0 |
474 |
|
long r = mix64(nextSeed()); |
475 |
|
long m = bound - 1; |
497 |
|
*/ |
498 |
|
public long nextLong(long origin, long bound) { |
499 |
|
if (origin >= bound) |
500 |
< |
throw new IllegalArgumentException(BadRange); |
500 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
501 |
|
return internalNextLong(origin, bound); |
502 |
|
} |
503 |
|
|
509 |
|
* (inclusive) and one (exclusive) |
510 |
|
*/ |
511 |
|
public double nextDouble() { |
512 |
< |
return (mix64(nextSeed()) >>> 11) * DOUBLE_ULP; |
512 |
> |
return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT; |
513 |
|
} |
514 |
|
|
515 |
|
/** |
523 |
|
*/ |
524 |
|
public double nextDouble(double bound) { |
525 |
|
if (!(bound > 0.0)) |
526 |
< |
throw new IllegalArgumentException(BadBound); |
527 |
< |
double result = (mix64(nextSeed()) >>> 11) * DOUBLE_ULP * bound; |
526 |
> |
throw new IllegalArgumentException(BAD_BOUND); |
527 |
> |
double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound; |
528 |
|
return (result < bound) ? result : // correct for rounding |
529 |
|
Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1); |
530 |
|
} |
542 |
|
*/ |
543 |
|
public double nextDouble(double origin, double bound) { |
544 |
|
if (!(origin < bound)) |
545 |
< |
throw new IllegalArgumentException(BadRange); |
545 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
546 |
|
return internalNextDouble(origin, bound); |
547 |
|
} |
548 |
|
|
570 |
|
*/ |
571 |
|
public IntStream ints(long streamSize) { |
572 |
|
if (streamSize < 0L) |
573 |
< |
throw new IllegalArgumentException(BadSize); |
573 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
574 |
|
return StreamSupport.intStream |
575 |
|
(new RandomIntsSpliterator |
576 |
|
(this, 0L, streamSize, Integer.MAX_VALUE, 0), |
611 |
|
public IntStream ints(long streamSize, int randomNumberOrigin, |
612 |
|
int randomNumberBound) { |
613 |
|
if (streamSize < 0L) |
614 |
< |
throw new IllegalArgumentException(BadSize); |
614 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
615 |
|
if (randomNumberOrigin >= randomNumberBound) |
616 |
< |
throw new IllegalArgumentException(BadRange); |
616 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
617 |
|
return StreamSupport.intStream |
618 |
|
(new RandomIntsSpliterator |
619 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
637 |
|
*/ |
638 |
|
public IntStream ints(int randomNumberOrigin, int randomNumberBound) { |
639 |
|
if (randomNumberOrigin >= randomNumberBound) |
640 |
< |
throw new IllegalArgumentException(BadRange); |
640 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
641 |
|
return StreamSupport.intStream |
642 |
|
(new RandomIntsSpliterator |
643 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
656 |
|
*/ |
657 |
|
public LongStream longs(long streamSize) { |
658 |
|
if (streamSize < 0L) |
659 |
< |
throw new IllegalArgumentException(BadSize); |
659 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
660 |
|
return StreamSupport.longStream |
661 |
|
(new RandomLongsSpliterator |
662 |
|
(this, 0L, streamSize, Long.MAX_VALUE, 0L), |
697 |
|
public LongStream longs(long streamSize, long randomNumberOrigin, |
698 |
|
long randomNumberBound) { |
699 |
|
if (streamSize < 0L) |
700 |
< |
throw new IllegalArgumentException(BadSize); |
700 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
701 |
|
if (randomNumberOrigin >= randomNumberBound) |
702 |
< |
throw new IllegalArgumentException(BadRange); |
702 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
703 |
|
return StreamSupport.longStream |
704 |
|
(new RandomLongsSpliterator |
705 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
723 |
|
*/ |
724 |
|
public LongStream longs(long randomNumberOrigin, long randomNumberBound) { |
725 |
|
if (randomNumberOrigin >= randomNumberBound) |
726 |
< |
throw new IllegalArgumentException(BadRange); |
726 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
727 |
|
return StreamSupport.longStream |
728 |
|
(new RandomLongsSpliterator |
729 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
742 |
|
*/ |
743 |
|
public DoubleStream doubles(long streamSize) { |
744 |
|
if (streamSize < 0L) |
745 |
< |
throw new IllegalArgumentException(BadSize); |
745 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
746 |
|
return StreamSupport.doubleStream |
747 |
|
(new RandomDoublesSpliterator |
748 |
|
(this, 0L, streamSize, Double.MAX_VALUE, 0.0), |
785 |
|
public DoubleStream doubles(long streamSize, double randomNumberOrigin, |
786 |
|
double randomNumberBound) { |
787 |
|
if (streamSize < 0L) |
788 |
< |
throw new IllegalArgumentException(BadSize); |
788 |
> |
throw new IllegalArgumentException(BAD_SIZE); |
789 |
|
if (!(randomNumberOrigin < randomNumberBound)) |
790 |
< |
throw new IllegalArgumentException(BadRange); |
790 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
791 |
|
return StreamSupport.doubleStream |
792 |
|
(new RandomDoublesSpliterator |
793 |
|
(this, 0L, streamSize, randomNumberOrigin, randomNumberBound), |
811 |
|
*/ |
812 |
|
public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) { |
813 |
|
if (!(randomNumberOrigin < randomNumberBound)) |
814 |
< |
throw new IllegalArgumentException(BadRange); |
814 |
> |
throw new IllegalArgumentException(BAD_RANGE); |
815 |
|
return StreamSupport.doubleStream |
816 |
|
(new RandomDoublesSpliterator |
817 |
|
(this, 0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound), |
826 |
|
* approach. The long and double versions of this class are |
827 |
|
* identical except for types. |
828 |
|
*/ |
829 |
< |
static final class RandomIntsSpliterator implements Spliterator.OfInt { |
829 |
> |
private static final class RandomIntsSpliterator |
830 |
> |
implements Spliterator.OfInt { |
831 |
|
final SplittableRandom rng; |
832 |
|
long index; |
833 |
|
final long fence; |
882 |
|
/** |
883 |
|
* Spliterator for long streams. |
884 |
|
*/ |
885 |
< |
static final class RandomLongsSpliterator implements Spliterator.OfLong { |
885 |
> |
private static final class RandomLongsSpliterator |
886 |
> |
implements Spliterator.OfLong { |
887 |
|
final SplittableRandom rng; |
888 |
|
long index; |
889 |
|
final long fence; |
939 |
|
/** |
940 |
|
* Spliterator for double streams. |
941 |
|
*/ |
942 |
< |
static final class RandomDoublesSpliterator implements Spliterator.OfDouble { |
942 |
> |
private static final class RandomDoublesSpliterator |
943 |
> |
implements Spliterator.OfDouble { |
944 |
|
final SplittableRandom rng; |
945 |
|
long index; |
946 |
|
final long fence; |