001 /*
002 * Java Genetic Algorithm Library (jenetics-3.0.0).
003 * Copyright (c) 2007-2014 Franz Wilhelmstötter
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 *
017 * Author:
018 * Franz Wilhelmstötter (franz.wilhelmstoetter@gmx.at)
019 */
020 package org.jenetics.util;
021
022 import static java.lang.Math.min;
023
024 import java.util.Objects;
025 import java.util.Random;
026 import java.util.function.LongSupplier;
027
028 import org.jenetics.internal.math.random;
029
030 /**
031 * An abstract base class which eases the implementation of {@code Random}
032 * objects which natively creates random {@code long} values. All other
033 * {@code Random} functions are optimized using this {@code long} values.
034 *
035 * [code]
036 * public class MyRandom64 extends Random64 {
037 * \@Override
038 * public long nextLong() {
039 * // Only this method must be implemented.
040 * ...
041 * }
042 * }
043 * [/code]
044 *
045 * @author <a href="mailto:franz.wilhelmstoetter@gmx.at">Franz Wilhelmstötter</a>
046 * @since 1.1
047 * @version 2.0 — <em>$Date: 2014-12-28 $</em>
048 */
049 public abstract class Random64 extends PRNG {
050
051 private static final long serialVersionUID = 1L;
052
053 protected Random64(final long seed) {
054 super(seed);
055 }
056
057 protected Random64() {
058 this(random.seed());
059 }
060
061 /**
062 * Force to explicitly override the Random.nextLong() method. All other
063 * methods of this class are implemented by calling this method.
064 */
065 @Override
066 public abstract long nextLong();
067
068
069 @Override
070 public boolean nextBoolean() {
071 return (nextLong() & 0x8000000000000000L) != 0L;
072 }
073
074 @Override
075 public int nextInt() {
076 return (int)(nextLong() >>> Integer.SIZE);
077 }
078
079 @Override
080 protected int next(final int bits) {
081 return (int)(nextLong() >>> (Long.SIZE - bits));
082 }
083
084 /**
085 * Optimized version of the {@link Random#nextBytes(byte[])} method for
086 * 64-bit random engines.
087 */
088 @Override
089 public void nextBytes(final byte[] bytes) {
090 for (int i = 0, len = bytes.length; i < len;) {
091 int n = min(len - i, Long.BYTES);
092
093 for (long x = nextLong(); --n >= 0; x >>= Byte.SIZE) {
094 bytes[i++] = (byte)x;
095 }
096 }
097 }
098
099 @Override
100 public float nextFloat() {
101 return random.toFloat2(nextLong());
102 }
103
104 /**
105 * Optimized version of the {@link Random#nextDouble()} method for 64-bit
106 * random engines.
107 */
108 @Override
109 public double nextDouble() {
110 return random.toDouble2(nextLong());
111 }
112
113
114 /**
115 * Create a new {@code Random64} instance, where the random numbers are
116 * generated by the given long {@code supplier}.
117 *
118 * @param supplier the random number supplier
119 * @return a new {@code Random64} instance
120 * @throws java.lang.NullPointerException if the given {@code supplier} is
121 * {@code null}.
122 */
123 public static Random64 of(final LongSupplier supplier) {
124 Objects.requireNonNull(supplier);
125
126 return new Random64() {
127 private static final long serialVersionUID = 1L;
128
129 @Override
130 public long nextLong() {
131 return supplier.getAsLong();
132 }
133
134 @Override
135 public void setSeed(final long seed) {
136 throw new UnsupportedOperationException(
137 "The 'setSeed(long)' method is not supported this instance."
138 );
139 }
140 };
141 }
142
143 }
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