001 /*
002 * Java Genetic Algorithm Library (jenetics-7.1.2).
003 * Copyright (c) 2007-2023 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@gmail.com)
019 */
020 package io.jenetics.ext.grammar;
021
022 import static java.util.Objects.requireNonNull;
023
024 import java.util.concurrent.atomic.AtomicInteger;
025 import java.util.function.IntUnaryOperator;
026
027 import io.jenetics.BitChromosome;
028 import io.jenetics.BitGene;
029 import io.jenetics.IntegerGene;
030 import io.jenetics.internal.util.Bits;
031 import io.jenetics.internal.util.Requires;
032 import io.jenetics.util.BaseSeq;
033
034 import io.jenetics.ext.grammar.Cfg.Rule;
035
036 /**
037 * Represents a mapping of a finite set of integers to symbol indexes. If more
038 * indexes are needed, the values are read from the beginning again. You have
039 * the possibility to create a {@code Codons} object from different chromosome
040 * types.
041 * <pre>{@code
042 * // Create 'classic' codons from a bit-chromosome, where
043 * // the genes are split into 8-bit junks and converted
044 * // into unsigned int values.
045 * final Codons codons = Codons.ofBitGenes(BitChromosome.of(10_000));
046 *
047 * // Creating a codons object from an integer chromosome.
048 * final var ich = IntegerChromosome.of(IntRange.of(0, 256), 1_000);
049 * final var codons = Codons.ofIntegerGenes(ich);
050 * }</pre>
051 *
052 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
053 * @since 7.1
054 * @version 7.1
055 */
056 public final class Codons implements SymbolIndex {
057
058 private final IntUnaryOperator _values;
059 private final int _length;
060
061 private final AtomicInteger _pos = new AtomicInteger(0);
062
063 /**
064 * Create a new {@code Codons} object from a given {@code codons} source and
065 * its {@code length}.
066 *
067 * @param codons the codons source
068 * @param length the length of the codons source
069 * @throws NullPointerException if the {@code codons} source is {@code null}
070 * @throws IllegalArgumentException if the given {@code length} is smaller
071 * than one
072 */
073 public Codons(final IntUnaryOperator codons, final int length) {
074 _values = requireNonNull(codons);
075 _length = Requires.positive(length);
076 }
077
078 @Override
079 public int next(final Rule<?> rule, final int bound) {
080 final int index = _pos.getAndUpdate(x -> (x + 1)%_length);
081 return _values.applyAsInt(index)%bound;
082 }
083
084 /**
085 * Creates a new, classical <em>codons</em> object from the given bit-genes.
086 * The genes is split into 8-bit chunks and converted into an unsigned
087 * {@code int[]} array.
088 * <pre>{@code
089 * final Codons codons = Codons.ofBitGenes(BitChromosome.of(10_000));
090 * }</pre>
091 *
092 * @param genes the genes used for creating the codons object
093 * @return a new <em>codons</em> object
094 */
095 public static Codons ofBitGenes(final BaseSeq<BitGene> genes) {
096 if (genes instanceof BitChromosome ch) {
097 return ofBytes(ch.toByteArray());
098 } else {
099 return ofBytes(toByteArray(genes));
100 }
101 }
102
103 private static Codons ofBytes(final byte[] bytes) {
104 final var values = new int[bytes.length];
105 for (int i = 0; i < values.length; ++i) {
106 values[i] = Byte.toUnsignedInt(bytes[i]);
107 }
108
109 return new Codons(i -> values[i], values.length);
110 }
111
112 static byte[] toByteArray(final BaseSeq<BitGene> genes) {
113 final byte[] bytes = Bits.newArray(genes.length());
114 for (int i = 0; i < genes.length(); ++i) {
115 if (genes.get(i).booleanValue()) {
116 Bits.set(bytes, i);
117 }
118 }
119
120 return bytes;
121 }
122
123 /**
124 * Creates a new <em>codons</em> object from the given int-genes.
125 *
126 * <pre>{@code
127 * final var chromosome = IntegerChromosome.of(IntRange.of(0, 256), 1_000);
128 * final var codons = Codons.ofIntegerGenes(chromosome);
129 * }</pre>
130 *
131 * @param genes the genes used for creating the codons object
132 * @return a new <em>codons</em> object
133 */
134 public static Codons ofIntegerGenes(final BaseSeq<IntegerGene> genes) {
135 return new Codons(i -> genes.get(i).intValue(), genes.length());
136 }
137
138 }
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