001/*
002 * Java Genetic Algorithm Library (jenetics-8.1.0).
003 * Copyright (c) 2007-2024 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 */
020package io.jenetics.ext.grammar;
021
022import static java.util.Objects.requireNonNull;
023
024import java.util.concurrent.atomic.AtomicInteger;
025import java.util.function.IntUnaryOperator;
026
027import io.jenetics.BitChromosome;
028import io.jenetics.BitGene;
029import io.jenetics.IntegerGene;
030import io.jenetics.internal.util.Bits;
031import io.jenetics.internal.util.Requires;
032import io.jenetics.util.BaseSeq;
033
034import 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 * {@snippet lang="java":
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 * }
051 *
052 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
053 * @since 7.1
054 * @version 7.1
055 */
056public 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 codon source
068         * @param length the length of the codon 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         * {@snippet lang="java":
089         * final Codons codons = Codons.ofBitGenes(BitChromosome.of(10_000));
090         * }
091         *
092         * @param genes the genes used for creating the codon 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         * {@snippet lang="java":
127         * final var chromosome = IntegerChromosome.of(IntRange.of(0, 256), 1_000);
128         * final var codons = Codons.ofIntegerGenes(chromosome);
129         * }
130         *
131         * @param genes the genes used for creating the codon 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}